JP6886864B2 - Tube heat exchanger and its manufacturing method - Google Patents

Description

The present invention relates to a multi-tube heat exchanger, which is a tube heat exchanger that can improve heat exchange performance between two heat media flowing through two or more flow paths in a tube and improve bendability during bending. And its manufacturing method.

Conventionally, heat exchange has been performed between the inner flow path and a plurality of outer flow paths arranged around the inner flow path in the pipe, and between the refrigerants flowing inside and outside.
Patent Document 1 discloses a double-tube heat exchanger in which heat exchange performance is improved while suppressing an increase in cost in a heat pump type heat source machine.

JP-A-2016-997075

One of the problems of the double-tube heat exchanger is to satisfy the demand for suppressing the cost increase and improving the heat exchange performance. It is possible to improve the heat exchange performance by increasing the length of the double-tube heat exchanger, but on the other hand, there is a problem that the heat exchanger becomes larger and the cost increases due to the increase in material cost. is there.

Therefore, an object of the present invention is to provide a multi-tube heat exchanger which can improve heat exchange performance and has excellent moldability while suppressing an increase in size and cost of the heat exchanger.

In the tube heat exchanger of the present invention, the inner peripheral side of the hollow tube is composed of at least two or more flow paths, and the metal tube heat exchanger exchanges heat with a plurality of heat media flowing through these flow paths. A exchanger comprising an outer tube and an inner tube housed inside the outer tube, and at least two or more flow paths are formed between the outer tube and the inner tube or inside the inner tube. A constant twist angle is spirally provided to the flow paths in their longitudinal directions, and the metal or alloy constituting the outer tube and the metal or alloy constituting the inner tube are made of dissimilar metals or dissimilar alloys, and the outer tube is formed. It is characterized in that a weld line having a constant twist angle is formed on the surface layer of the pipe.
In the tube heat exchanger according to the present invention, the same twist is applied to the entire vertical cross section in the longitudinal direction of the tube, two or more flow paths have a predetermined twist angle, and the spiral angle of the surface layer of the tube. Is 10 ° or more and 80 ° or less.
If the twist angle of the tube surface layer is less than 10 °, the increase in the flow path due to the spiraling is insufficient and the effect of increasing the heat exchange performance is small. Further, if the temperature exceeds 80 °, the pressure loss of the refrigerant becomes large.

The tube heat exchanger according to the present invention is characterized in that the twist angle of the weld line on the surface layer of the tube is 10 ° or more.
The tube heat exchanger according to the present invention is preferably made of aluminum or an aluminum alloy.
As a method for manufacturing a heat transfer tube by extrusion using an aluminum alloy, there is a port hole extrusion method as a method for manufacturing a heat transfer tube having a straight groove. The port hole extrusion method is a method in which a mandrel and a die are connected by a bridge, and an aluminum alloy material is extruded through a plurality of port holes formed between them to form a raw tube. Since the aluminum alloy material is separated at the port hole, merged, welded again, and integrated, a plurality of welded portions called weld lines are formed linearly along the length direction of the heat transfer tube. There is no problem in strength of the weld line as long as sufficient diffusion is obtained at the bonding interface, but if it is insufficient and unwelded, the bonding strength is low. In the latter case, when the heat transfer tube is processed, cracks or breaks are likely to occur starting from those unwelded parts, which is likely to cause molding defects, and cracks are likely to occur during bending. In the present invention, the workability is improved by promoting the diffusion of the weld portion generated in the raw pipe as it is extruded by the combined processing of twisting and drawing and the heat treatment, and increasing the joint strength thereof.

The manufacturing method according to the present invention is a metal tube heat exchanger in which the inner peripheral side of a hollow tube is composed of at least two or more flow paths and heat exchanges with a plurality of heat media flowing through those flow paths. In the case of manufacturing a tube heat exchanger in which these flow paths spirally have a constant twist angle in the longitudinal direction and a weld line having a constant twist angle is formed on the surface layer of the tube. A pipe having a plurality of linear flow paths is manufactured from one or more metal extruded raw pipes, and a composite process of simultaneously applying drawing and twisting to the pipe is performed one or more times. Finally, the heat treatment is performed at a high temperature of 400 ° C. or higher for 4 hours or longer.
Many tube heat exchangers have been proposed in which two tubes are configured. For example, a multi-tube has been proposed in which two refrigerants flow through the inner pipe and the outer pipe surrounding the inner pipe, and the inner pipe is spirally twisted to improve the heat exchange performance between the refrigerants. In that case, the number of man-hours increases, which causes a high cost.
Therefore, the tube heat exchanger of the present invention is manufactured by, for example, the above-mentioned manufacturing method, and twisting is directly applied to the extruded raw tube having a linear flow path, so that the process is simple and low cost. At the same time, after the combined processing in which twisting and drawing are performed at the same time, heat treatment is performed at a high temperature to promote the diffusion of the welded portion and enhance the bonding strength.

According to the present invention, since a plurality of spiral flow paths are provided inside, the flow path length becomes longer according to the spiral angle, so that the heat exchange performance between the refrigerants is excellent and the bonding strength of the weld portion is increased. It is possible to provide a tube-type heat exchanger that is high and has excellent bending workability.

It is a perspective view of the tube type heat exchanger of the 1st Embodiment which concerns on this invention. It is a perspective view which made a part of the tube type heat exchanger of the 2nd Embodiment which concerns on this invention a cross section. It is a side view which cut the part of the outer tube in the tube type heat exchanger of the 2nd Embodiment which concerns on this invention. The side view which shows the weld line formed in the outer tube of the same tube type heat exchanger. It is a perspective view which made a part of the composite element tube for manufacturing the same tube type heat exchanger as a fracture surface. It is a side view which shows the manufacturing apparatus which performs the twist pull-out process at the time of manufacturing the same tube type heat exchanger. It is a top view of the floating frame seen from the arrow X direction in FIG. The side view which shows the whole structure of the 2nd manufacturing apparatus. The plan view which shows the whole structure of the 2nd manufacturing apparatus. The plan view which shows the state which wound and unwound the raw tube around the unwinding side capstan of the 2nd manufacturing apparatus. It is a partial cross-sectional photograph of the tube type heat exchanger obtained in the Example. It is a side photograph which removed a part of the outer tube of the same tube type heat exchanger. It is sectional drawing of the composite raw tube used for manufacturing the tube type heat exchanger of an Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the drawings used in the following description, for the purpose of emphasizing the characteristic parts, the characteristic parts may be enlarged for convenience, and the dimensional ratios of the respective components may not be the same as the actual ones. Absent. Further, for the same purpose, a part that is not a feature may be omitted in the figure.

[Heat exchanger]
FIG. 1 is a perspective view showing a tube heat exchanger according to the first embodiment of the present invention.
The tubular heat exchanger 50 of the first embodiment includes an outer pipe (main pipe) 51 and an inner pipe 52, and a plurality of partition walls 53 are formed radially at predetermined intervals in the circumferential direction of the inner pipe 52, and these partition walls are formed. The 53 is integrally connected to the outer pipe 51 and the inner pipe 52 and extends spirally in the length direction of these pipes.
By extending these partition walls 53 in a spiral shape, a plurality of twisted flow paths (first flow paths) 54 partitioned by the outer pipe 51, the inner pipe 52, and the partition wall 53 are formed on the outside of the inner pipe 52. ing. Further, a second flow path 55 is formed inside the inner pipe 52.
Since the partition wall 53 formed on the outside of the inner pipe 52 is spirally formed with a predetermined twist angle and spiral pitch along the length direction of the inner pipe 52, the pipe type of the second embodiment described later will be described. Similar to the heat exchanger 10, a plurality of twisting flow paths 54 are spirally formed with a predetermined spiral pitch and twist angle so as to surround the inner tube 52.
The twist angle of these twist flow paths 54 is formed to be the same as the twist angle θ1 of the tubular heat exchanger 10 of the second embodiment described later.

Further, in the present embodiment, six twisting flow paths 54 are formed around the inner pipe 52, and the diameter of the inner pipe 52 is formed to be about half the diameter of the outer pipe 51 in the radial direction of the outer pipe 51. The height of the twisted flow path 54 along the above is formed to be about the radius of the inner pipe 52.
As the tube heat exchanger 10, one made of aluminum or an aluminum alloy can be used. When an aluminum alloy is used for the tube heat exchanger 10, the aluminum alloy is not particularly limited, and is represented by a pure aluminum system such as 1050, 1100, 1200 specified by JIS, or 3003 to which Mn is added. A 3000 series aluminum alloy or the like can be applied. In addition to the above, the tube heat exchanger 10 may be configured by using any of the 5000 series to 7000 series aluminum alloys specified in JIS, or an aluminum alloy not specified in JIS may be used. Of course it is good. In addition, in this specification, "aluminum" is a concept including those made of an aluminum alloy and pure aluminum.
In the present embodiment, the tube heat exchanger 50 is made of aluminum or an aluminum alloy, but the tube heat exchanger 50 may be made of a copper alloy or an iron alloy such as stainless steel. Since the tube heat exchanger 50, which is the object of the present invention, can be applied as long as it is a material that can be drawn out by a drawing die, a tube made of another metal or alloy such as a copper-based alloy or an iron-based alloy is used. The present invention may be carried out.

In this tube heat exchanger 50, a composite raw tube having a non-spiral partition wall extending in a strip shape along the length direction of these tubes between an outer tube and an inner tube is manufactured by extrusion processing. This composite raw tube can be manufactured by twisting and drawing with the manufacturing apparatus A described later shown in FIGS. 6 and 7.

Since a plurality of first flow paths 54 and second flow paths 55 formed spirally along the length direction are provided inside the tube heat exchanger 50, the inside of the tube heat exchanger 50 is provided. It is possible to improve the heat exchange efficiency between the refrigerants flowing through the water.
Further, the first flow path 54 and the second flow path 55 can be used as a flow path for the refrigerant, and one of them can be applied as an outward path and the other can be applied as a return path.

FIG. 2 shows the tube heat exchanger of the second embodiment.
The tubular heat exchanger 10 has, for example, an inner tube 8 having an outer diameter of about 3 to 15 mm or 3 to 10 mm and having a four-leaf clover-shaped cross-sectional shape, and a circular tubular outer tube 9 covering the inner tube 8. Consists of.
As shown in FIG. 2, the inner pipe 8 is provided with four flow path pipes 8A formed by bending a thin aluminum plate into a clover leaf shape inside the outer pipe 9 so as to be symmetrical in cross section. .. As shown in the cross-sectional portion of FIG. 2, each flow path pipe 8A is composed of a head portion 8a and a neck portion 8b, and in each flow path pipe 8A, the outer peripheral side of the head portion 8a is arranged so as to be in contact with the inner surface of the outer pipe 9. The neck portion 8b of the flow path pipe 8A is continuous with the neck portion 8b of another adjacent flow path pipe 8A on the central side of the outer pipe 8. By connecting and integrating the four flow path pipes 8A in this way, the four flow path pipes 8A are arranged in a four-leaf cloverleaf shape in the cross section.

In the flow path pipe 8A, a first flow path (twisted flow path) 10a is formed inside the head 8a, and the other flow path pipe 8A on the side of the head 8a of the flow path pipe 8A and adjacent to the flow path pipe 8A. A second flow path (twisted flow path) 10b is formed at a position surrounded by the head portion 8a and the outer pipe 9. Further, in the four flow path pipes 8A, a third flow path 10d is formed at the center of the portion to which the neck portions 8b are connected.
The inner tube 8 and the outer tube 9 are made of the pure aluminum or aluminum alloy described above, but the inner tube 8 and the outer tube 9 may be made of the same type of pure aluminum or aluminum alloy, and different types of pure aluminum or aluminum. It may be formed from an alloy. For example, the strength of the inner pipe 8 may be made lower than the strength of the outer pipe 9 by changing the composition of the aluminum alloy constituting the inner pipe 8 and the aluminum alloy forming the outer pipe 9, and the elongation of the inner pipe 8 is outside. Pure aluminum or an aluminum alloy can be used properly depending on the inner tube 8 and the outer tube 9 to be applied, for example, the elongation can be made larger than the elongation of the tube 9.
The inner pipe 8 and the outer pipe 9 used in this embodiment may be formed of a copper alloy or an iron alloy such as stainless steel as described above. In this embodiment, the inner tube 8 and the outer tube 9 made of aluminum or an aluminum alloy will be described as an example, but the tube heat exchanger intended by the present invention can be applied as long as it is a material that can be drawn out by a drawing die. Therefore, it is needless to say that a tube made of another alloy such as a copper-based alloy or an iron-based alloy may be used and applied to the present invention.
The inner tube 8 and the outer tube 9 do not have to be made of the same material, and the outer tube 9 may be made of a copper alloy, the inner tube 8 may be made of an aluminum alloy, or the like.

In the present embodiment, the inner pipe 8 and the outer pipe 9 are spirally twisted at a predetermined pitch in the length direction thereof. That is, inside the outer tube 9, the four flow path tubes 8A are spirally extended at the same twist angle θ1.
FIG. 3 shows the twist angle θ1 of the flow path tube 8A. In this embodiment, as an example, the entire outer diameter of the tube heat exchanger is set to 10 mm and the twist angle θ1: 25 °. It is desirable that the twist angle θ1 is an angle that does not cause buckling when the tube heat exchanger 10 is manufactured by the manufacturing apparatus described later. Buckling of the pipe can also be prevented.
For the twist angle θ1, for example, when a part of the outer tube 9 is excluded and the inner tube 8 is viewed from the side as shown in FIG. 3, the spiral drawn by the flow path tube 8A is observed, and the straight line portion thereof is extracted. It is grasped as the intersection angle with the central axis of the tube heat exchanger 10 (outer tube 9), but it can be grasped exactly as described below.
First, the raw pipe before twisting (the flow path raw pipe 7 described later) is mounted on a surface plate, and a height gauge is used to draw a linear rule on the outer peripheral surface of the flow path raw pipe 7 in the length direction. Form a line. For example, a straight scribe line is formed along the length direction of the flow path raw pipe 7 at the central portion in the width direction of one head 7a.

Next, the tube type heat exchanger 10 is manufactured by applying the twisting process described later. The scribe line of the manufactured tube heat exchanger 10 has a spiral shape.
Next, it can be obtained from the pitch p of the spiral scribe line and the circumferential length a of the outer peripheral surface 8a of the inner pipe 8 by using the following (Equation 1).
θ1 = tan-1 (a / p) ... (Equation 1)
In order to improve the efficiency of heat exchange with the refrigerant flowing inside at a torsion angle θ1 within this range and prevent buckling of the pipe during manufacturing, the torsion angle θ1 should be in the range of 15 ° to 80 °. The twist angle θ1 = 15 ° to 40 ° is desirable, and the twist angle θ1 = 15 ° to 30 ° is more preferable.
The outer pipe 9 is a pipe material having a circular outer shape in cross section. The diameter of the outer tube 9 corresponds to the outer diameter of the tube heat exchanger 10, and can be set in a range of 3 mm or more and 15 mm or less, but is not limited to this range. The wall thickness of the outer tube 9 is about the same as the wall thickness of the inner tube 8, but one may be thicker or thinner than the other, and there is no particular limitation.

As shown in FIG. 4, four weld lines WLs arranged at equal intervals along the circumferential direction are formed on the outer peripheral surface 9a of the outer pipe 9. Further, as shown in FIG. 4 and the like, the four weld lines WL are spirally formed along the outer peripheral surface 9a of the outer pipe 9 in the length direction of the outer pipe 9 with the same twist angle θ2. There is.
When the outer tube 9 is manufactured by extrusion processing and twisting, the weld line WL is based on a portion where aluminum materials are merged and welded in a material flow path leading to a die of an extruder, and that portion is twisted. It is formed in a spiral shape.

The weld line WL penetrates the pipe wall of the outer pipe 9 in the thickness direction at each position spirally formed along the outer peripheral surface 9a of the outer pipe 9, and from the outer peripheral surface 9a of the outer pipe 9 to the outer pipe 9 It is formed so as to reach the inner peripheral surface of the.
The number of weld lines WL is not limited to four as in the present embodiment. At the time of manufacturing the outer pipe 9 of the present embodiment, the aluminum material (billet) housed in the extrusion processing apparatus is divided into a plurality of flow paths and pumped to be formed in a portion where the aluminum material (billet) is merged inside the die. Therefore, the number of weld lines WL is determined according to the number of flow paths in the extruder. For example, a number of weld lines WL such as three or four may be formed along the outer peripheral surface 9a of the outer pipe 9.

In the present embodiment, the twist angle θ2 of the spirally formed weld line WL is, for example, 10 ° or more and 80 ° or less. As will be described later, the tube heat exchanger 10 of the present embodiment is formed by applying a twisting process to the composite element tube 4 having a cross-sectional shape shown in FIG. Therefore, the spiral pitch of the weld line WL formed on the outer tube 9 after the twisting process and the spiral pitch of the flow path tube 8A forming the inner tube 8 are substantially the same.
For the twist angle θ2, for example, when the outer tube 9 is viewed from the side as shown in FIG. 4, the spiral drawn by the weld line WL is observed, and the straight line portion thereof is extracted to extract the straight portion of the spiral and the tube heat exchanger 10 (outer tube 9). It is grasped as the intersection angle with the central axis of, but it can be grasped exactly as explained below.

A method of obtaining the twist angle (lead angle) θ2 on the outer peripheral surface 9a of the outer pipe 9 will be described.
First, the outer tube (external tube 6 described later) before twisting is mounted on the surface plate, and a height gauge is used to extend a linear scribe line on the outer peripheral surface of the outer tube 6 in the length direction. To form.
Next, the tube type heat exchanger 10 is manufactured by applying the twisting process described later. The scribe line of the manufactured tube heat exchanger 10 has a spiral shape.
Next, it can be obtained from the pitch p of the spiral scribe line and the circumferential length a of the outer peripheral surface 9a of the outer tube 9 using the following (Equation 1).
θ1 = tan-1 (a / p) ... (Equation 1)
When the weld line WL generated when the outer tube 6 is formed is clearly formed, the weld line may be used as a reference for the pitch p instead of the above-mentioned scribe line.

The composite base pipe 4 shown in FIG. 5 is composed of an outer base pipe 6 and an inner base pipe 7 made of the same material as the above-mentioned aluminum or aluminum alloy, and the inner pipe 7 is a four-leaf clover having a cross-sectional shape shown in FIG. It is composed of four flow path raw pipes 7A constituting the mold. The outer diameter of the outer tube 6 is slightly larger than the outer diameter of the outer tube 9 of the tube heat exchanger 10 described above with reference to FIG.
As shown in FIG. 5, each flow path raw pipe 7A is composed of a head portion 7a and a neck portion 7b, and in each flow path raw pipe 7A, the outer peripheral side of the head portion 7a is arranged so as to be in contact with the inner surface of the outer raw pipe 6 and flows. The neck portion 7b of the road element pipe 7A is continuous with the neck portion 7b of another adjacent flow path element tube 7A on the central side of the outer element tube 6. By connecting and integrating the four flow path raw pipes 7A in this way, the four flow path raw pipes 7A are arranged in a four-leaf cloverleaf shape in the cross section.
In the composite raw pipe 4, the first flow path 4a is formed inside each flow path raw pipe 7A, and the second flow is surrounded by these and the outer raw pipe 6 between the flow path raw pipes 7A and 7A. The structure is similar to that of the tube heat exchanger 10 in that the path 4b is formed and the second flow path 4c is formed so as to be surrounded by the neck portion 7b of the four flow path raw tubes 7A.

However, the cross-sectional shape of the flow path tube 7 is slightly different from the cross-sectional shape of the flow path tube 8 in the tube heat exchanger 10 described above with reference to FIG.
In the composite pipe 4 shown in FIG. 5, the cross-sectional shape of the head portion 7a of the flow path pipe 7A is formed in an elliptical shape slightly closer to a circle than the cross-sectional shape of the head portion 8a of the flow path pipe 8 shown in FIG. On the other hand, the cross-sectional shape of the head portion 8a of the flow path pipe 8 is formed in an elliptical shape close to a flat shape as shown in FIG.
In the composite pipe 4 shown in FIG. 5, the second flow path 4b is formed to be wide on the side close to the outer pipe 6 and slightly narrower on the side near the center of the outer pipe 6. In the tube heat exchanger 10 shown in FIG. 4, the second flow path 10b is narrowly shaped from the side close to the outer tube 9 to the side close to the center of the outer tube 9.

The reason why the cross-sectional shape of the composite body tube 4 and the cross-sectional shape of the tube heat exchanger 10 are different is that the composite body tube 4 is plastically deformed at least once by using a die in a manufacturing apparatus described later. This is because the twisting process is added to 4. By this twisting, the four flow path raw pipes 7A formed linearly along the length direction of the composite raw pipe 4 are twisted, and the four flows having the twist angle and the twist pitch shown in FIG. A tube heat exchanger 10 having a road tube 8A can be obtained.
By twisting the composite base pipe 4 while applying a pulling force with a die using a manufacturing apparatus described later, even a thin composite base pipe 4 made of aluminum or an aluminum alloy and having an outer diameter of about 3 to 15 mm can be used as a pipe. Can be twisted without causing breakage or cracking.

When used as a refrigerant flow pipe of a heat exchanger, for example, a high-pressure refrigerant flows inside the tube heat exchanger 10 depending on the type of heat exchanger. Therefore, the tube heat exchanger 10 is required to have sufficient withstand voltage strength against the internal pressure.
According to the tube heat exchanger 10 of the present embodiment, the weld line WL is formed in a spiral shape, so that the withstand voltage strength is higher than that of the structure in which the weld line WL is provided in a straight line. .. When the internal pressure of the tubular heat exchanger 10 increases, a stress is applied to the inner peripheral surface of the outer tube 9 to push the outer tube 9 outward in the radial direction. Therefore, in the tube heat exchanger 10, cracks due to an increase in internal pressure are likely to be formed along the longitudinal direction of the outer tube 9. On the other hand, since the weld line WL has a different structure as compared with other parts, it tends to be a starting point of cracks when corrosion or the like occurs.
According to the present embodiment, since the weld line WL is spirally formed on the tube wall of the outer tube 9, the linear weld line WL is provided even when the internal pressure is increased. The structure is less likely to crack along the spiral weld line WL. Therefore, it is possible to provide the tube heat exchanger 10 having excellent pressure resistance. Further, as will be described later, the outer tube 9 is strongly machined by twisting in addition to being pulled out by a die, and the weld line WL portion is strengthened, so that cracks are unlikely to occur from this surface as well.

When the outer tube 9 of the tube heat exchanger 10 shown in FIG. 4 is cut open by the length of the spiral pitch and expanded into a rectangular shape, the length of one circumference of the weld line WL can be obtained diagonally on the expanded surface. Therefore, if the length is measured, the length of one round of the weld line WL can be measured.
The weld line WL of such a tube heat exchanger 10 draws a spiral with a sufficiently large twist angle θ2. Therefore, the spirally formed weld line WL extends at a sufficient inclination with respect to the length direction of the tubular heat exchanger 10, which is the direction in which cracks are likely to occur in response to an increase in internal pressure. .. As a result, it is possible to more effectively suppress the formation of cracks along the weld line WL.

In the present embodiment, the spiral weld line WL is formed spirally and intermittently along the length direction of the outer tube 9. That is, a partially interrupted portion is formed in the weld line WL. As described above, the weld line WL is a welded portion between aluminum materials when extrusion processing is performed. Therefore, the structure of the weld line WL in the outer tube 9 is different from that of other parts of the outer tube 9.
As will be described later, the tube heat exchanger 10 of the present embodiment is manufactured by repeatedly drawing and twisting a composite element tube 4 having an outer element tube 6 formed by extrusion processing. The weld line WL is mixed with the surrounding structure by being subjected to the processing a plurality of times, and the boundary becomes ambiguous. As a result, the weld line WL partially disappears and becomes intermittent. Diffusion is also achieved by heat treatment, and mixing with surrounding tissues is promoted.

According to this embodiment, the weld line WL is formed spirally and intermittently. In addition, the tissue of the portion where the weld line WL has disappeared is mixed with the surrounding tissue and homogenized. Therefore, the strength of the outer pipe 9 along the weld line WL can be increased. This makes it possible to provide the tube heat exchanger 10 having high pressure resistance.
Further, it is said that the weld line WL is preferentially corroded because a solid solution component is precipitated at the time of formation. According to the present embodiment, since the weld line WL is formed spirally and intermittently along the length direction, the corroded portion does not extend continuously, and the decrease in pressure resistance due to corrosion can be suppressed. ..

The length of each spiral and intermittently formed weld line WL is preferably 5 mm or less. By setting the length of each weld line WL to 5 mm or less, it is possible to effectively suppress the decrease in pressure resistance due to the weld line WL.

When the outer tube 9 of the multiple twisted tube 10 is immersed in a 5% sodium hydroxide aqueous solution at 50 ° C. for 1 minute and etched, the weld line WL floats on the surface in the form of white streaks. Further, since the white streak-shaped portion is a welded portion, there is a difference in the etching method as compared with other portions, and fine pits are generated. In this state, in the weld line WL, light is scattered and can be identified as a streak-like portion.

According to the present embodiment, since a plurality of first flow paths 10a and second flow paths 10b formed spirally along the length direction are provided inside the tube heat exchanger 10, the tube is provided. It is possible to improve the heat exchange efficiency between the refrigerants flowing inside the heat exchanger 10. The tubular heat exchanger 10 provided with the spiral first flow path 10a and the second flow path 10b can be formed by applying a twist to the composite element tube 4 shown in FIG. Further, by applying a twist, the weld line WL can be formed in a spiral shape, and it is possible to provide a tube heat exchanger 10 provided with an outer tube 9 having excellent pressure resistance to internal pressure. Further, different refrigerants can flow through the first flow path 4a and the second flow path 4b, and the flow of one flow path and the other flow path can be reversed and applied to the outward path and the return path. You can also.
The application of the tube heat exchanger 10 is not limited to heat exchangers, but is _{used for various purposes such as aftercooler applications for compressors, CO 2} piping applications for vending machines, piping applications for large boilers, and piping applications for water heaters. Of course, it can be widely applied.

[Production method]
Hereinafter, an embodiment of a method for manufacturing the tube heat exchanger 10 according to the present invention will be described with reference to the drawings. The method for manufacturing the tube heat exchanger 10 includes an extrusion molding step and a torsional drawing step in this order.

<Extrusion molding process>
First, an outer tube 6 is formed by an extrusion molding step, and an inner tube 7 having a cross-sectional shape shown in FIG. 5 is inserted into the outer tube 6 to obtain a composite tube 4.
The outer tube 6 is manufactured (tube extrusion molding step) by extrusion molding a billet made of an aluminum material. The outer tube 6 formed by the extrusion molding step is formed with, for example, four weld lines WL extending linearly in the length direction of the outer tube 6. The four weld lines WL are arranged at equal intervals (90 ° intervals) along the circumferential direction of the outer tube 6, for example. By combining the outer tube 6 with the inner tube 7 formed into a four-leaf cloverleaf, the composite tube 4 shown in FIG. 5 can be obtained.

<Twist pulling process, empty pulling process>
Next, the twist pulling step and the empty pulling step will be described.
The twist-pulling step is a step of spiraling the weld line WL and the flow path raw pipe 7A by applying a twist to the above-mentioned composite raw pipe 4 while pulling out.
Further, the dry pulling step is a step of pulling out the pipe material without applying twist to adjust the outer shape of the pipe material and bring the outer pipe and the inner pipe into closer contact with each other.

In the present specification, in the process from the composite raw tube 4 provided with the linear flow path raw tube 7A to the tubular heat exchanger 10, about half the twist is applied as compared with the tubular heat exchanger 10. The intermediate formed product is called an "intermediate twisted pipe". Further, the “tube material” in the present specification is a superordinate concept of the composite element tube 4, the intermediate twisted tube and the tube heat exchanger 10, and may indicate a tube to be processed regardless of the stage of the manufacturing process. is there.
In the present specification, the "first stage" and the "second stage" mean a front-back relationship (that is, upstream and downstream) along the processing order of the pipe material, and do not mean the arrangement of each part in the manufacturing apparatus. The pipe material is conveyed from the front stage (upstream) side to the rear stage (downstream) side in the manufacturing apparatus of the pipe type heat exchanger 10. The portion arranged in the front stage is not always arranged in the front, and the portion arranged in the rear stage is not always arranged in the rear.

<Manufacturing equipment that performs twisting and pulling processes and empty pulling processes>
FIG. 6 is a side view showing a manufacturing apparatus A for manufacturing a tube heat exchanger 10 by applying a twisting and pulling step twice to a composite raw tube 4. First, the manufacturing apparatus A will be described, and then the twist-pulling step and the empty-pulling step using the manufacturing apparatus A will be described.

The manufacturing apparatus A includes a revolution mechanism 30, a floating frame 34, an unwinding bobbin (first bobbin) 11, a first guide capstan 18, a first drawing die 1, and a first revolution capstan. It includes 21, a revolution flyer 23, a second revolution capstan 22, a second drawing die 2, a second guide capstan 61, and a take-up bobbin (second bobbin) 71. The details of each part will be described below.

(Revolution mechanism)
The revolution mechanism 30 has a rotating shaft 35 including a front shaft 35A and a rear shaft 35B, a drive unit 39, a front stand 37A, and a rear stand 37B.
The revolution mechanism 30 rotates the rotating shaft 35, and the first revolution capstan 21, the second revolution capstan 22, and the revolution flyer 23 fixed to the rotating shaft 35.
Further, the revolution mechanism 30 maintains a stationary state of the floating frame 34 located coaxially with the rotating shaft 35 and supported by the rotating shaft 35. As a result, the unwinding bobbin 11, the first guide capstan 18, and the first drawing die 1 supported by the floating frame 34 are maintained in a stationary state.

Both the front shaft 35A and the rear shaft 35B have a cylindrical shape with a hollow inside. Both the front shaft 35A and the rear shaft 35B are arranged coaxially with the revolution center axis C (pass line of the first drawing die) as the center axis. The front shaft 35A is rotatably supported by the front stand 37A via a bearing type bearing 36, and extends from the front stand 37A toward the rear (rear stand 37B side). Similarly, the rear shaft 35B is rotatably supported by the rear stand 37B via bearings, and extends from the rear stand 37B toward the front (front stand 37A side). A floating frame 34 is bridged between the front shaft 35A and the rear shaft 35B.

The drive unit 39 includes a drive motor 39c, a linear motion shaft 39f, belts 39a and 39d, and pulleys 39b and 39e. The drive unit 39 rotates the front shaft 35A and the rear shaft 35B.
The drive motor 39c rotates the linear motion shaft 39f. The linear motion shaft 39f extends in the front-rear direction at the lower part of the front stand 37A and the rear stand 37B.
A pulley 39b is attached to the front end portion 35Ab of the front shaft 35A at a tip penetrating the front stand 37A. The pulley 39b is interlocked with the linear motion shaft 39f via the belt 39a. Similarly, the rear end portion 35Bb of the rear shaft 35B has a pulley 39e attached to the tip penetrating the rear stand 37B and interlocks with the linear motion shaft 39f via the belt 39d. As a result, the front shaft 35A and the rear shaft 35B rotate synchronously around the revolution center axis C.

A first revolution capstan 21, a second revolution capstan 22, and a revolution flyer 23 are fixed to the rotating shaft 35 (front shaft 35A and rear shaft 35B). As the rotary shaft 35 rotates, these members fixed to the rotary shaft 35 revolve around the revolution center axis C.

(Floating frame)
The floating frame 34 is supported by bearings 34a at the ends 35Aa and 35Ba of the front shaft 35A and the rear shaft 35B of the rotating shaft 35 facing each other. The floating frame 34 also supports the unwinding bobbin 11, the first guide capstan 18, and the first drawing die 1.

FIG. 7 is a plan view of the floating frame 34 as viewed from the direction of arrow X in FIG. As shown in FIGS. 6 and 7, the floating frame 34 has a box shape that opens vertically. The floating frame 34 has a front wall 34b and a rear wall 34c that face each other in the front-rear direction, and a pair of support walls 34d that face each other in the left-right direction and extend in the front-rear direction.

Through holes are provided in the front wall 34b and the rear wall 34c, and the ends 35Aa and 35Ba of the front shaft 35A and the rear shaft 35B are inserted, respectively. A bearing 34a is interposed between the ends 35Aa and 35Ba and the through holes of the front wall 34b and the rear wall 34c. As a result, it is difficult for the rotation of the rotating shaft 35 (front shaft 35A and rear shaft 35B) to be transmitted to the floating frame 34. The floating frame 34 keeps a stationary state with respect to the ground G even when the rotating shaft 35 is in a rotating state. A weight that biases the center of gravity of the floating frame 34 with respect to the revolution center axis C may be provided to stabilize the stationary state of the floating frame 34.

As shown in FIG. 7, the pair of support walls 34d has the unwinding bobbin 11, the first guide capstan 18, and the first drawing die 1 arranged on both sides in the left-right direction (vertical direction in FIG. 6). There is. The pair of support walls 34d rotatably support the bobbin support shaft 12 that holds the unwinding bobbin 11 and the rotation shaft J18 of the first guide capstan 18. Further, the support wall 34d supports the first drawing die 1 via a die support (not shown).

(Unwinding bobbin)
A composite raw tube 4 (see FIG. 5) is wound around the unwinding bobbin 11. The unwinding bobbin 11 unwinds the composite raw tube 4 and supplies it to the subsequent stage.
The unwinding bobbin 11 is detachably attached to the bobbin support shaft 12.

As shown in FIG. 7, the bobbin support shaft 12 extends in a direction orthogonal to the rotating shaft 35. Further, the bobbin support shaft 12 is supported by a floating frame 34 so as to rotate and rotate. Here, the rotation rotation means rotation around the central axis of the bobbin support shaft 12 itself. The bobbin support shaft 12 holds the unwinding bobbin 11 and rotates on its axis in the supply direction of the unwinding bobbin 11 to assist the unwinding bobbin 11 in feeding the composite bobbin 4.

The unwinding bobbin 11 is removed when all the wound composite raw pipes 4 are supplied, and is replaced with another unwinding bobbin. The removed empty unwinding bobbin 11 is attached to an extruder that forms the composite base pipe 4, and the composite base pipe 4 is wound again. The unwinding bobbin 11 is supported by the floating frame 34 and does not revolve. Therefore, even if the composite raw tube 4 is randomly wound around the unwinding bobbin 11, the supply can be performed without any problem, and the unwinding bobbin 11 can be used without rewinding. Further, the weight of the unwinding bobbin 11 does not limit the number of revolutions of the revolution rotation for imparting a twist to the composite body pipe 4 in the manufacturing apparatus A. Therefore, the long composite raw tube 4 can be wound around the unwinding bobbin 11. As a result, it is possible to impart a twist to the long composite raw tube 4, and it is possible to improve the manufacturing efficiency.

The bobbin support shaft 12 is provided with a brake portion 15. The brake unit 15 applies a braking force to the rotation of the bobbin support shaft 12 with respect to the floating frame 34. That is, the brake unit 15 regulates the rotation of the unwinding bobbin 11 in the unwinding direction. A rear tension is applied to the composite raw pipe 4 conveyed in the unwinding direction by the braking force of the brake portion 15. As the brake unit 15, for example, a powder brake or a band brake capable of adjusting torque as a braking force can be adopted.

(1st guide capstan)
The first guide capstan 18 has a disk shape. A composite raw pipe 4 unwound from the unwinding bobbin 11 is wound around the first guide capstan 18 once. The tangential direction of the outer circumference of the first guide capstan 18 coincides with the revolution center axis C. The first guide capstan 18 guides the composite raw pipe 4 along the first direction D1 on the revolution center axis C.
The first guide capstan 18 is supported by a floating frame 34 so as to rotate and rotate. Further, on the outer circumference of the first guide capstan 18, the guide rollers 18b that can rotate and rotate are arranged side by side. In the first guide capstan 18 of the present embodiment, the plurality of guide rollers 18b rotate individually, but if the plurality of guide rollers 18b rotate, the composite raw pipe 4 can be smoothly conveyed. In FIG. 7, the guide roller 18b is not shown.

As shown in FIG. 7, a pipeline guide portion 18a is provided between the first guide capstan 18 and the unwinding bobbin 11. The pipeline guide portion 18a is, for example, a plurality of guide rollers arranged so as to surround the composite raw pipe 4. The pipeline guide portion 18a guides the composite raw pipe 4 supplied from the unwinding bobbin 11 to the first guide capstan 18.

Instead of the first guide capstan 18, a guide tube having a traverse function may be provided between the unwinding bobbin 11 and the first drawing die 1. When the guide pipe is provided, the distance between the unwinding bobbin 11 and the first drawing die 1 can be shortened, and the space in the factory can be effectively utilized.

(1st pull-out die)
The first drawing die 1 reduces the diameter of the composite raw pipe 4 (tube material 5). The first drawing die 1 is fixed to the floating frame 34. The first drawing die 1 has the first direction D1 as the drawing direction. The center of the first drawing die 1 coincides with the revolution center axis C of the rotating shaft 35. Further, the first direction D1 is parallel to the revolution center axis C.
Lubricating oil is supplied to the first drawing die 1 by the lubricating oil supply device 9A fixed to the floating frame 34. As a result, the pulling force of the first pulling die 1 can be reduced.
The pipe material 5 that has passed through the first drawing die 1 is introduced into the front shaft 35A through a through hole provided in the front wall 34b of the floating frame 34.

(1st revolution capstan)
The first revolution capstan 21 has a disk shape. The first revolution capstan 21 is arranged in a lateral hole 35Ac that radially penetrates the inside and outside of the hollow front shaft 35A. The first revolving capstan 21 is supported by a support 21a fixed to the outer peripheral portion of the rotating shaft 35 (front shaft 35A) with the center of the disk as the rotating shaft J21.

In the first revolution capstan 21, one of the tangents on the outer circumference coincides with the revolution center axis C.
A pipe material 5 conveyed in the first direction D1 on the revolution center axis C is wound around the first revolution capstan 21 for one or more turns. The first revolution capstan 21 winds the pipe material 5 and pulls it out from the inside of the front shaft 35A to guide it to the revolution flyer 23.

The first revolution capstan 21 revolves around the revolution center axis C together with the front shaft 35A. The revolution center axis C extends in a direction orthogonal to the rotation axis J21 of the rotation rotation of the first revolution capstan 21. The pipe material is twisted between the first revolution capstan 21 and the first drawing die 1. As a result, the pipe material changes from the composite raw pipe 4 to the intermediate twisted pipe 10C.

Along with the first revolution capstan 21, a drive motor 20 is provided on the front shaft 35A. The drive motor 20 drives and rotates the first revolution capstan 21 in the winding direction (conveying direction) of the pipe material 5. As a result, the first revolution capstan 21 applies a forward tension to the pipe material 5 for passing through the first drawing die 1.

The first revolution capstan 21 and the drive motor 20 are preferably arranged at positions symmetrical with respect to the revolution center axis C so that the center of gravity is located on the revolution center axis C of the front shaft 35A. Thereby, the balance of rotation of the front shaft 35A can be stabilized. If the weight difference between the first revolution capstan 21 and the drive motor 20 is large, a weight may be provided to stabilize the center of gravity.

(Revolution flyer)
The revolution flyer 23 reverses the conduit of the pipe material 5 between the first drawing die 1 and the second drawing die 2. The revolving flyer 23 reverses the pipe material 5 conveyed in the first direction D1 which is the drawing direction of the first drawing die 1, and sets the conveying direction to the second direction D2 which is the drawing direction of the second drawing die 2. Turn to. More specifically, the revolution flyer 23 guides the pipe material 5 from the first revolution capstan 21 to the second revolution capstan 22.

The revolution flyer 23 has a plurality of guide rollers 23a and a guide roller support (not shown) that supports the guide rollers 23a. Here, the guide roller support is not shown in order to eliminate the complexity, but the guide roller support is supported by the rotating shaft 35. However, the guide roller is not indispensable for the structure of the flyer, and it may be simply a plate-like structure for the pipe to pass through and a shape to which a ring for passing the pipe is attached. This ring may be provided on a plate-shaped member. A part of this ring may be composed of a part of this plate-shaped member. The plate-shaped member may be supported by the rotating shaft 35 in the same manner as the guide roller support.
The guide rollers 23a are arranged in a bow shape that curves outward with respect to the revolution center axis C. The guide roller 23a itself rolls and smoothly conveys the pipe material 5. The revolution flyer 23 rotates around the floating frame 34, the first drawing die 1 supported in the floating frame 34, and the unwinding bobbin 11 around the revolution rotation center axis C.

One end of the revolution flyer 23 is located outside the first revolution capstan 21 with respect to the revolution center axis C. Further, the other end of the revolution flyer 23 passes through a lateral hole 35Bc that radially penetrates the inside and outside of the hollow rear shaft 35B and extends to the inside of the rear shaft 35B. The revolution flyer 23 guides the pipe material 5 wound around the first revolution capstan 21 and extended outward to the rear shaft 35B side. Further, the revolution flyer 23 feeds the pipe material 5 inside the rear shaft 35B on the revolution center axis C along the second direction D2.

The revolution flyer 23 of the present embodiment has been described as being for transporting the pipe material 5 by the guide roller 23a. However, the revolution flyer 23 may be formed from a strip formed in an arch shape, and the pipe material 5 may be transported by sliding one surface of the strip.
Further, in FIG. 7, a case where the pipe material 5 passes outside the guide roller 23a is illustrated.
However, when the rotation speed of the revolution flyer 23 is high, the pipe material 5 may derail from the revolution flyer due to centrifugal force. In such a case, it is preferable to further provide a guide roller 23a on the outside of the pipe material 5.
A plurality of dummy flyers having the same weight as the revolution flyer 23 and extending from the front shaft 35A to the rear shaft 35B and rotating synchronously with the revolution flyer 23 may be provided. Thereby, the rotation of the rotating shaft 35 can be stabilized.

(Second revolution capstan)
The second revolution capstan 22 has a disk shape like the first revolution capstan 21. The second revolving capstan 22 is supported by a support 22a provided at the tip of the end portion 35Bb of the rear shaft 35B in a state where it can rotate freely. Further, on the outer circumference of the second revolving capstan 22, guide rollers 22c that can rotate and rotate are arranged side by side. In the second revolution capstan 22 of the present embodiment, the plurality of guide rollers 22c rotate individually, and the pipe material 5 can be smoothly conveyed by this rotation.

In the second revolution capstan 22, one of the tangents on the outer circumference coincides with the rotation center axis C.
A pipe material 5 conveyed in the second direction D2 on the rotation center axis C is wound around the second revolution capstan 22 for one or more turns. The second revolution capstan 22 feeds the wound pipe material in the second direction D2 on the rotation center axis C.

The second revolution capstan 22 rotates around the rotation center axis C together with the rear shaft 35B. The rotation center axis C extends in a direction orthogonal to the rotation axis J22 of the second revolution capstan 22. The pipe material 5 unwound from the second revolution capstan 22 is reduced in diameter in the second drawing die 2. Since the second drawing die 2 is stationary with respect to the ground G, the pipe material 5 can be twisted between the second revolving capstan 22 and the second drawing die 2. As a result, the pipe material 5 is processed from the intermediate twisted pipe 10C into a pipe heat exchanger 10.

The support 22a that supports the second revolution capstan 22 supports the weight 22b at a position symmetrical to the second revolution capstan 22 with respect to the rotation center axis C. The weight 22b stabilizes the rotational balance of the rear shaft 35B.

(Second pull-out die)
The second drawing die 2 is arranged after the second revolution capstan 22. The second drawing die 2 has the opposite second direction D2 as the drawing direction. The second direction D2 is a direction parallel to the rotation center axis C. The second direction D2 is opposite to the first direction D1, which is the drawing direction of the first drawing die 1. The pipe material 5 passes through the second drawing die 2 along the second direction D2. The second drawing die 2 is stationary with respect to the ground G. The center of the second drawing die 2 coincides with the revolution center axis C of the rotating shaft 35.

The second drawing die 2 is supported by the gantry 62, for example, via a die support (not shown). Further, lubricating oil is supplied to the second drawing die 2 by the lubricating oil supply device 9B attached to the gantry 62. As a result, the pulling force of the second pulling die 2 can be reduced.
Due to the diameter reduction and twisting of the second drawing die 2, the pipe material 5 changes from the intermediate twisted pipe 10C to the pipe heat exchanger 10.

(Second guide capstan)
The second guide capstan 61 has a disk shape. The tangential direction of the outer circumference of the second guide capstan 61 coincides with the revolution center axis C. A pipe material 5 conveyed in the second direction D2 on the revolution center axis C is wound around the second guide capstan 61 for one or more turns.

The second guide capstan 61 is rotatably supported by the gantry 62 about the rotation shaft J61. Further, the rotating shaft J61 of the second guide capstan 61 is connected to the drive motor 63 via a drive belt or the like. The second guide capstan 61 is driven and rotated by the drive motor 63 in the winding direction (conveying direction) of the tube heat exchanger 10. As the drive motor 63, it is preferable to use a torque motor capable of torque control.

A forward tension is applied to the pipe material 5 by driving the second guide capstan 61. As a result, the pipe material 5 is conveyed forward by applying the drawing stress required for processing in the second drawing die 2.

(Take-up bobbin)
The take-up bobbin 71 is provided at the end of the pipeline of the tubular heat exchanger 10 and collects the tubular heat exchanger 10. A pulley 72 is provided in front of the take-up bobbin 71. The take-up bobbin 71 or the pulley 72 has a traverse function and winds the tube heat exchanger 10 around the take-up bobbin 71 in an aligned winding state or a random lap winding state.

The take-up bobbin 71 is detachably attached to the bobbin support shaft 73. The bobbin support shaft 73 is supported by the gantry 75 and is connected to the drive motor 74 via a drive belt or the like. The take-up bobbin 71 is driven and rotated by the drive motor 74, and takes up the pipe material 5 without loosening it. The take-up bobbin 71 is removed when the tube heat exchanger 10 is sufficiently wound and replaced with another take-up bobbin 71.

<Twisting and pulling process>
A method of manufacturing the tube heat exchanger 10 by using the manufacturing apparatus A described above will be described.
First, as a preliminary step, the composite raw tube 4 is unwound and wound around the bobbin 11 in a coil shape. Further, the unwinding bobbin 11 is set in the floating frame 34 of the manufacturing apparatus A. Further, the composite raw pipe 4 (pipe material 5) is unwound from the unwinding bobbin 11 and set in the conduit of the composite raw pipe 4 in advance. Specifically, the pipe material 5 is divided into a first guide capstan 18, a first drawing die 1, a first revolution capstan 21, a revolution flyer 23, a second revolution capstan 22, and a second drawing die 2. , The second guide capstan 61 and the take-up bobbin 71 are passed in this order and set.

In the manufacturing process of the tube heat exchanger 10, the description will be given along the transfer path of the tube material.
First, the composite raw tube 4 (tube material 5) is sequentially unwound from the unwinding bobbin 11.
Next, the composite raw pipe 4 unwound from the unwinding bobbin 11 is wound around the first guide capstan 18. The first guide capstan 18 guides the composite raw tube 4 into the die hole of the first drawing die 1 located on the rotation center axis C (first guiding step).

Next, the composite raw tube 4 is passed through the first drawing die 1. Further, in the subsequent stage of the first drawing die 1, the pipe material 5 is wound around the first revolution capstan 21 and rotated around the rotation axis. As a result, the diameter of the pipe material 5 is reduced and a twist is applied (first twisting / pulling step).

In the first torsional pull-out step, forward tension is applied to the pipe material 5 by the drive motor 20 that drives the first revolution capstan 21. At the same time, a rear tension is applied to the pipe material 5 by the brake portion 15 of the unwinding bobbin 11. Therefore, it is possible to apply an appropriate tension to the pipe material 5, and it is possible to impart a stable twist angle to the pipe material 5 without causing buckling or breakage.

The pipe material 5 is passed through the first drawing die 1 and then wound around the rotating first revolution capstan 21. The pipe material 5 is pulled out by the first drawing die 1 and twisted by the first revolution capstan 21. As a result, the linear flow path pipe 7A inside the pipe material 5 (composite raw pipe 4) is twisted to form the pipe heat exchanger 10. By the first twisting and pulling step, the composite raw pipe 4 becomes an intermediate twisted pipe 10C. The intermediate twisted pipe 10C is a pipe material in an intermediate stage in the manufacturing process of the pipe type heat exchanger 10, and is in a state where a flow path pipe having a twist angle shallower than that of the spiral flow path pipe 7 of the pipe type heat exchanger 10 is formed. Is.

In the first twist-drawing step, the pipe material 5 (composite raw pipe 4) is twisted and at the same time pulled out with a drawing die. That is, the pipe material 5 is subjected to a composite stress due to simultaneous processing of twisting and drawing. Under the combined stress, the shear stress of the pipe material 5 becomes smaller than that in the case where only the twisting process is performed, and a large twist can be applied to the pipe material 5 before the buckling stress of the pipe material 5 is reached. As a result, it is possible to impart a large twist while suppressing the occurrence of buckling of the pipe material 5.

A first guide capstan 18 is provided in front of the first drawing die 1 to regulate the rotation of the pipe material 5. That is, the pipe material 5 is restrained from being deformed in the twisting direction in the front stage of the first drawing die 1. The pipe material 5 is twisted between the first drawing die 1 and the first revolving capstan 21. That is, in the first torsional drawing step, the region (machining area) where the pipe material 5 is twisted is limited between the first drawing die 1 and the first revolution capstan 21.
There is a correlation between the length of the machining area and the limit twist angle (maximum twist angle that can be twisted without buckling), and even if a large twist angle is given by shortening the machining area. Buckling is unlikely to occur. By providing the first guide capstan 18, the machining area can be set short without twisting in the front stage of the first drawing die 1. Further, by reducing the distance between the first drawing die 1 and the first revolution capstan 21, the machining area can be set short, and a large twist can be applied to the pipe material 5 without causing buckling.

The diameter reduction ratio of the pipe material 5 by the first drawing die 1 is preferably 2% or more. A correlation is observed between the limit twist angle and the diameter reduction ratio, and the limit twist angle tends to increase as the diameter reduction ratio at the time of drawing increases. That is, if the diameter reduction ratio is too small, the effect of pulling out is poor and it is difficult to obtain a large twist angle. Therefore, it is preferably 2% or more. For the same reason, it is more preferable that the diameter reduction ratio is 5% or more.
On the other hand, if the diameter reduction ratio becomes too large, fracture is likely to occur at the processing limit, so it is preferably 40% or less.

Next, the pipe material 5 is wound around the revolution flyer 23, and the transport direction of the pipe material 5 is directed to the second direction D2 on the rotation center axis C. Further, the pipe material 5 is wound around the second revolution capstan 22 and the pipe material 5 is introduced into the second drawing die 2 (second induction step). As a result, the transport direction of the pipe material 5 is reversed from the first direction D1 to the second direction D2, and is aligned with the center of the second drawing die 2. The revolution flyer 23 rotates around the floating frame 34 about the revolution center axis C. The first revolution capstan 21, the revolution flyer 23, and the second revolution capstan 22 rotate synchronously about the rotation center axis C. Therefore, between the first revolution capstan 21 and the second revolution capstan 22, the pipe material 5 does not rotate relatively and is not twisted.

Next, the pipe material 5 that rotates together with the second revolution capstan 22 is passed through the second drawing die 2. As a result, the diameter of the pipe material 5 is reduced and twisted, and the twist angle of the flow path pipe is further increased (second twisting and pulling step). By this second twisting and pulling step, the intermediate twisted pipe 10C becomes a pipe type heat exchanger 10.

In the second torsional pull-out step, forward tension is applied to the pipe material 5 by the drive motor 63 that drives the second guide capstan 61. When a torque controllable torque motor is used as the drive motor 63, the second guide capstan 61 can adjust the forward tension applied to the pipe material 5. By adjusting the forward tension with the second guide capstan 61, it is possible to apply an appropriate tension to the pipe material 5 in the second torsional pull-out step. As a result, a stable twist angle can be imparted to the pipe material 5 without causing buckling or breakage.

The pipe material 5 passes through the second drawing die 2 after being wound around the second revolving capstan 22 that revolves. The diameter of the pipe material 5 is reduced by the second drawing die 2, and the pipe material 5 is twisted by the second revolution capstan 22. As a result, a larger twist is applied to the flow path pipe of the pipe material 5, and the twist angle of the flow path pipe becomes large. By the second twisting and pulling step, the intermediate twisted pipe 10C becomes a pipe type heat exchanger 10.

In the front stage of the second drawing die 2, the pipe material 5 is wound around the second revolution capstan 22. In the subsequent stage of the second drawing die 2, a second guide capstan 61 is provided to regulate the rotation of the pipe material 5. That is, the pipe material 5 is restrained from being deformed in the twisting direction before and after the second drawing die 2, and the pipe material 5 is twisted between the second revolution capstan 22 and the second guide capstan 61. Granted. That is, in the second twist-drawing step, the region (machining area) where the pipe material 5 is twisted is limited between the second revolution capstan 22 and the second drawing die 2. As described above, by shortening the processing area, buckling is less likely to occur even if a large twist angle is applied. By providing the second guide capstan 61, the machining area can be set short without twisting in the subsequent stage of the second drawing die 2.

In the present embodiment, the second revolution capstan 22 is provided behind the rear stand 37B (on the side of the second drawing die 2), but the second revolution capstan 22 is the front stand 37A. It may be located between the rear stand 37B. However, by arranging the second revolution capstan 22 rearward with respect to the rear stand 37B and bringing it closer to the second drawing die 2, the machining area in the second torsional drawing step can be shortened. Thereby, the occurrence of buckling can be suppressed more effectively.

In the second torsional pulling step, twisting and pulling are performed in the same manner as in the first torsional pulling step, and a composite stress is applied to the pipe material 5. As a result, before the buckling stress of the pipe material 5 is reached, a large twist can be applied to the pipe material while suppressing the occurrence of buckling.

The diameter reduction ratio of the pipe material 5 by the second drawing die 2 is preferably 2% or more (more preferably 5% or more) and 40% or less, as in the first torsional drawing step.
If the first drawing die 1 is subjected to a large diameter reduction (for example, a diameter reduction of 30% or more), the pipe material 5 is work-hardened, so that the second drawing die 2 is subjected to a large diameter reduction. It becomes difficult. Therefore, the total of the diameter reduction ratio of the first drawing die 1 and the diameter reduction ratio of the second drawing die 2 is preferably 4% or more and 50% or less.

<Sky pulling process>
Next, the pipe material 5 is passed through the finish drawing die 70 (finish drawing step). By passing the pipe material 5 through the finish drawing die 70, the surface is shaped and the uneven thickness of the wall thickness is reduced. Further, even if the pipe material 5 is slightly crushed or otherwise deformed, the deformation can be corrected by undergoing this finish drawing step to obtain the pipe material 5 having a predetermined roundness. The force for transporting the pipe material 5 with respect to the pulling load of the finishing pulling die 70 is applied by the drive motor 74 provided on the take-up bobbin 71. Although the description is omitted in FIG. 6, a pedestal (not shown) for supporting the finish drawing die 70 is erected between the gantry 62 and the gantry 75. The gantry is provided with a supply nozzle (not shown) and an oil tank for supplying lubricating oil to the finish drawing die 70.

Further, a heat transfer tube having a stable surface texture and shape can be manufactured by performing an air-pulling step after the twist-pulling step (the first twist-pulling step and the second twist-pulling step). The diameter reduction ratio of the pipe material 5 in the dry drawing step is preferably 25% or less. Further, the total diameter reduction ratio of the first drawing step, the second drawing step and the empty drawing step is preferably 30% or more.

<Recovery process>
Next, the pipe material 5 is wound around the take-up bobbin 71 and collected. The take-up bobbin 71 is rotated by the drive motor 74 in synchronization with the transport speed of the pipe material 5, so that the pipe material 5 can be wound up without slack.
Through the above steps, the tube heat exchanger 10 can be manufactured by using the manufacturing apparatus A.

<Heat treatment process>
Next, the heat treatment step will be described.
The heat treatment step is performed at a high temperature of 400 ° C. or higher for 4 hours or longer after the twisting and pulling step. The heat treatment step is a heat treatment step in which the pipe material 5 is annealed. By performing the heat treatment step, the strain of the aluminum material can be removed and the bonding of the welded portion can be further strengthened.

According to the torsional drawing step of the present embodiment, the linear weld line WL formed on the outer tube 9 in the extrusion molding step becomes spiral. As a result, it is possible to form a weld line WL in which cracks are unlikely to occur with an increase in internal pressure.
Further, according to the twisting / pulling step of the present embodiment, the twisting is repeated a plurality of times. As a result, the weld line WL formed in the extrusion molding process mixes with the surrounding structure and the boundary becomes ambiguous. As a result, the weld line WL can be partially eliminated and formed intermittently, and as a result, the tube heat exchanger 10 having high pressure resistance can be manufactured.

According to the manufacturing method of the present embodiment, by directly applying a twist to the flow path raw pipe 7A, the weld line WL and the flow path raw pipe 7A can be spirally and intermittently formed at the same time. .. As a result, the multi-twisted tube that simultaneously achieves the effect of improving the pressure resistance by forming the weld line WL spirally and intermittently and the effect of improving the heat exchange rate by the spiral flow path tube 8A. 10 can be manufactured.

According to the manufacturing method of the present embodiment, a weld line generated in the composite raw pipe 4 by extrusion is performed by performing a heat treatment (heat treatment step) after twisting and drawing the composite raw pipe 4 formed by extrusion processing. The diffusion bonding of WL can be strengthened and the bonding strength can be increased.

According to the manufacturing method of the present embodiment, the total diameter reduction ratio of each step (first pulling step, second pulling step and empty pulling step) is 30% or more. By setting the diameter reduction ratio to 30% or more, a large twist can be imparted. Further, according to the manufacturing method of the present embodiment, the diameter reduction ratio of each step is 25% or less. When the diameter reduction ratio in each process is 25% or less, work hardening can be suppressed and the diameter reduction in the subsequent process can be smoothly performed.

In the torsional pull-out step of the present embodiment, the first torsional pull-out step and the second torsional pull-out step are performed again on the tube heat exchanger 10 formed through the above-mentioned steps to impart a larger twist angle. You may. In this case, the tube heat exchanger 10 that has undergone the above steps is heat-treated (annealed). Further, the unwinding bobbin 11 is wound around the unwinding bobbin 11, and the unwinding bobbin 11 is attached to a manufacturing apparatus A having a first drawing die having an appropriate diameter reduction ratio and a second drawing die. Further, the manufacturing apparatus A can manufacture a multi-twisted tube having a larger twist angle by going through the same steps (first twist-pulling step and second twist-pulling step) as described above.

According to the torsional drawing step of the present embodiment, since the drawing is performed at the same time as the twisting, the outer diameter and the cross-sectional area of the starting material and the final product are different. Further, since the combined stress of twist and diameter reduction is applied to the pipe material 5, it is possible to reduce the shear stress required for the twisting process, and a large twist is applied to the pipe material 5 before the buckling stress of the pipe material 5 is reached. Can be granted. Therefore, the flow path pipe 8A having a large twist angle θ1 and the flow path pipe 8A having a thin wall thickness and the outer pipe 9 can be manufactured without causing buckling. In the tube heat exchanger 10, the heat exchange efficiency can be improved by increasing the twist angle θ1 of the flow path tube 8A. Further, the tube heat exchanger 10 can be made lighter and cheaper by reducing the material cost by reducing the wall thickness. That is, according to the present embodiment, it is possible to manufacture the tube heat exchanger 10 which is lightweight, inexpensive, and has high heat exchange efficiency.

According to the torsional pull-out step of the present embodiment, since the straight tubular flow path pipe 7A is twisted and the diameter is reduced, a large twisting angle can be imparted while suppressing the occurrence of buckling. In the present embodiment, the outer diameter of the composite element tube 4 as a material is 1.1 times or more the outer diameter of the final product, the tube heat exchanger 10.

According to the twisting and pulling step of the present embodiment, the pipe material 5 is twisted and pulled out by the first revolution capstan 21 between the first pulling die 1 and the second pulling die 2. Further, the drawing directions of the first drawing die 1 and the second drawing die 2 are reversed. As a result, the pipe material 5 can be twisted by matching the twisting directions in the first twisting and pulling step and the second twisting and pulling step. Further, it is not necessary to revolve the unwinding bobbin 11 which is the start end of the pipeline of the pipe material 5 and the take-up bobbin 71 which is the end of the pipeline. Since the speed of the line depends on the rotation speed, the rotation speed can be easily increased in the twisting and pulling step of the present embodiment in which the unwinding bobbin 11 or the winding bobbin 71, which is a heavy object, is not rotated. That is, according to this embodiment, the line speed can be easily increased.
Further, in the present embodiment, since the unwinding bobbin 11 is not revolved, a long composite raw tube 4 (tube material 5) can be wound around the unwinding bobbin 11. Therefore, according to the twist-pulling step of the present embodiment, the unwinding bobbin 11 can be twisted in a single stroke without replacing the unwinding bobbin 11. That is, according to this embodiment, mass production of the tube heat exchanger 10 becomes easy.

In the twisting / pulling step of the present embodiment, the pipe material 5 is twisted through at least two twisting / pulling steps. Therefore, it is possible to give a large twist angle by accumulating the twist angles given in the twist pulling step of each stage.

According to the torsional pull-out step of the present embodiment, forward tension and backward tension are applied to the pipe material 5 in the first torsional pull-out step and the second torsional pull-out step. The forward tension is applied to the pipe material 5 by the second guide capstan 61, and the rear tension is applied to the pipe material 5 by the brake portion 15 that brakes the unwinding bobbin 11. As a result, an appropriate tension can be stably applied to the pipe material 5 to be processed. Since there is no slack in the pipe line of the pipe material 5 and the straight tubular flow path element pipe 7A enters the drawing die without misalignment, a stable twist angle can be imparted to the pipe material 5 without causing buckling or breakage.

In the present embodiment, the centers of the first drawing die 1 and the second drawing die 2 die holes are located on the revolution center axis C. As a result, the pipe material 5 passing through the die hole can be arranged linearly with respect to the die hole, so that the diameter of the pipe material 5 can be uniformly reduced and buckling at the time of twisting can be suppressed. In the first drawing die 1 and the second drawing die 2, the position of the die hole with respect to the revolution center axis C is allowed as long as the diameter of the pipe material 5 can be reduced normally.

In the present embodiment, it is assumed that the unwinding bobbin 11 is supported by the floating frame 34 and the winding bobbin 71 is installed on the ground G. However, either the unwinding bobbin 11 or the winding bobbin 71 may be supported by the floating frame 34. That is, in FIG. 7, the unwinding bobbin 11 and the winding bobbin 71 may be interchanged and arranged. In this case, the transport path of the pipe material 5 is reversed. Further, the first drawing die 1 and the second drawing die 2 are arranged interchangeably, and the drawing directions of the respective drawing dies 1 and 2 are reversed and arranged along the conveying direction. Further, in the capstans located before and after the drawing dies 1 and 2, the capstan located at the rear stage of the drawing dies is driven in the winding direction (conveying direction) of the pipe material to apply a forward tension against the pulling force of the drawing dies. give away.
By the steps described above, the tube heat exchanger 10 having the configuration shown in FIGS. 2 to 4 can be manufactured.
According to the torsional drawing step of the present embodiment, the weld becomes spiral in the extrusion molding step.
Further, according to the torsional extraction step of the present embodiment, by repeating the torsional extraction a plurality of times, a large amount of strain is introduced, diffusion is promoted at the time of the final heat treatment, the welded portion is strongly joined, and the bending workability is improved. An excellent tube heat exchanger can be manufactured.

As described above, the multiple twisted tube of the present invention can adopt various shapes as illustrated in FIGS. 1, 2, and 3. Further, in the present invention, the twisting flow path is not limited to two layers, and a multi-layer structure having three or more layers may be formed inside the outer pipe.
For example, by twisting a composite raw pipe containing a plurality of flow path pipes having a small particle size so as to have three or more layers inside the outer pipe, the manufacturing apparatus A twists the three or more layers. A tube heat exchanger provided with a flow path can be manufactured.

"Second manufacturing equipment"
8 and 9 show a second manufacturing apparatus B used for manufacturing the tube heat exchanger 10, FIG. 8 shows a side surface of the overall structure of the manufacturing apparatus B, and FIG. 9 shows the manufacturing apparatus B. The plane of the whole structure is shown.
In this manufacturing apparatus B, the unwinding side capstan 80 that holds the composite raw tube 4 shown in FIG. 5 in a coiled state as shown in FIGS. 8 and 10 and the unwinding side capstan 80 A rotating means 81 for rotating the unwound composite raw tube 4 together with the unwinding side capstan 80 is provided. Further, the manufacturing apparatus B winds a drawing die 82 through which the composite element tube 4 sent out from the unwinding side capstan 80 is passed, and a tube heat exchanger 10 which has been twisted and drawn through the drawing die 82. It is equipped with a pull-out side capstan 83 that is sent out while being sent out.

As shown in FIG. 9, the unwinding side capstan 80 is rotatably and horizontally rotatably around the bearing portion 87 attached to the upper end portion of the support column members 85 and 86 made of steel materials erected in the front and rear at a distance. It is supported by the supported hollow shaft portion 88. The unwinding side capstan 80, the die 82, and the pulling out side capstan 83 are sequentially arranged along the extension line in the length direction of the hollow shaft portion 88, and the composite raw pipe 4 is the hollow shaft portion 88 and the unwinding side. The capstan 80, the drawing die 82, and the drawing side capstan 83 are moved and processed in this order. Therefore, in the following description, the upstream side will be appropriately referred to as the front stage side and the downstream side will be referred to as the rear stage side along the moving direction of the composite pipe 4.

The hollow shaft portion 88 is horizontally provided supported by bearing members 85a and 86a provided at the upper end portion of the support column member 85 and the upper end portion of the support column member 86, respectively, and one end 88a thereof is upstream from the upper end portion of the support column member 85. The other end 88b is projected from the upper end of the support column member 86 to the outside on the downstream side, and is supported horizontally and rotatably around the axis. A pair of first support frames 90 extending diagonally adjacent to the hollow shaft portion 88 are provided on the other end side of the hollow shaft portion 88, and the disc portion 80a of the unwinding side capstan 80 is provided by the tip portion 90a thereof. The central axis of is rotatably supported.
A second support frame 91 is provided on the other end side of the hollow shaft portion 88 so as to extend diagonally with respect to the hollow shaft portion 88, and the extension frame 92 extending to the tip end side of the second support frame 91 A weight body 93 is attached. The first support frame 90 and the second support frame 91 are connected to the other end 88b of the hollow shaft portion 88 so as to be arranged in a V shape, and are connected to the first support frame 90 by rotation of the hollow shaft portion 88 around the axis. The second support frame 92 is rotated while being supported in a V shape.

Further, the unwinding side capstan 80 is supported by the first frame 90 so that the extension line of the central axis of the hollow shaft portion 88 is approximated to the tangent line of the outer peripheral edge of the unwinding side capstan 80. Therefore, when the unwinding side capstan 80 rotates with the rotation of the hollow shaft portion 88, the unwinding side capstan 80 rotates so as to orbit around the extension line of the central axis of the hollow shaft portion 88. Similarly, as the hollow shaft portion 88 rotates, the weight body 93 also rotates so as to orbit around the extension line of the central axis of the hollow shaft portion 88.
The unwinding side capstan 80 is configured so that the composite raw tube 4 can be wound along the outer peripheral edge of the disk portion 80a.

For example, when the hollow shaft portion 88 is rotated so that the unwinding side capstan 80 is in the lowermost position as shown in FIG. 8, the hollow shaft portion 88 is slightly above the uppermost portion of the unwinding side capstan 80. The extension of the central axis passes. Alternatively, when the hollow shaft portion 88 is rotated so that the unwinding side capstan 80 is in the uppermost position, the extension line of the central shaft portion of the central shaft portion 88 is slightly below the lowermost portion of the unwinding side capstan 80. Passes.
An inlet portion 88c having a size capable of inserting the composite base pipe 4 is formed in the opening on the one end 88a side of the hollow shaft portion 88, and the previous composite base pipe is formed in the opening on the other end 88b side of the hollow shaft portion 88. An outlet portion 88d from which 4 can be pulled out is formed.

Therefore, the composite raw pipe 4 that has passed through the inside of the hollow shaft portion 88 can be introduced along the tangent line of the outer circumference of the unwinding side capstan 80 and wound around the outer circumference of the unwinding side capstan 80. , For example, the composite element tube 4 wound around the outer circumference of the unwinding side capstan 80 for one round can be unwound from the outer circumference of the unwinding side capstan 80 and led out to the drawing die 82 side.
FIG. 10 briefly shows an example of the winding state and the unwinding state of the composite raw tube 4 with respect to the unwinding side capstan 80. In FIG. 10, C0 indicates the axial center of the composite raw tube 4 on the front stage side wound around the unwinding side capstan 80, and C1 indicates the axial center of the composite raw tube 4 unwound from the unwinding side capstan 80. There is.

The first frame 90 and the second frame 91 are extended in a V shape on the other end side of the hollow shaft portion 88, and the unwinding side capstan 80 and the weight body 93 are attached to their tip ends. However, the weight and mounting position of the weight body 93 and the unwinding side capstan 80 are set so that the weight balance can be balanced when they rotate. That is, when the weight body 93 and the unwinding side capstan 80 are swiveled by the rotation of the hollow shaft portion 88, the unwinding is performed so that the balance of the rotational moments of both is balanced and the vibration accompanying the rotation of both is as small as possible. The weights and mounting positions of the side capstan 80 and the weight 93 are adjusted.

A support plate 95 is erected between the upper part of the support plate member 85 and the upper part of the support plate member 86, the drive motor 96 is attached to the support plate 95, and a power transmission device 97 such as an endless belt is connected to the output shaft 96a of the drive motor 96. Has been done. The power transmission device 97 is connected to one end side of the hollow shaft portion 88 located above the power transmission device 97, and the hollow shaft portion 88 can be rotationally driven by the rotation of the output shaft 96a of the drive motor 96.
The drive motor 96, the power transmission device 97, and the hollow shaft portion 88 rotate the unwinding side capstan 80 and the weight body 93 integrally, and the drive motor 96, the power transmission device 97, and the hollow shaft portion 88 wind the capstan 80 and the weight body 93. A rotating means 81 for rotationally driving the output side capstan 80 is configured.

The unwinding side capstan 80 is provided on the downstream side of the outlet portion 88d of the hollow shaft portion 88, and the drawing die 82 is provided on the downstream side of the hollow shaft portion 88 while being supported by the support column member 98. As shown in FIG. 8, the drawing die 82 is installed at an intermediate position between the outlet portion 88d of the hollow shaft portion 88 and the drawing die 82 so that the die hole is arranged at the same height as the outlet portion 88d of the hollow shaft portion 88. The outer peripheral edge of the unwinding side capstan 80 is arranged so as to coincide with the path line. In this example, the drawing die 82 is attached to the upper end of the support column member 98 via a hollow support frame 99. Further, above the support frame 99, a tank 100 for supplying lubricating oil to the die holes of the drawing die 82 and a flexible supply pipe 101 are installed.

The drawing die 82 has a die hole through which the composite raw pipe 4 is inserted, and performs empty drawing to reduce the outer diameter of the composite raw pipe 4. The diameter reduction ratio of the drawing die 82 is set to about 5 to 40% in the case of the composite raw tube 4 made of aluminum or an aluminum alloy. If the diameter reduction ratio is too small, the effect of pulling out is poor and it is difficult to obtain a large twist angle. Therefore, it is preferably 5% or more. On the other hand, if the diameter reduction ratio becomes too large, the composite raw tube 4 is likely to break at the processing limit, so it is preferably 40% or less.
Further, when the composite raw pipe 4 passes through the die hole, the unwinding side capstan 80 is rotated, so that the composite raw pipe 4 is reduced in diameter by the die hole of the drawing die 82 and at the same time twisted. Therefore, the composite raw tube 4 is twisted and processed into the tube heat exchanger 10 shown in FIGS. 2 to 4.

A pull-out side capstan 83 is provided on the downstream side of the pull-out die 82 supported by the support support member 98, and the pull-out side capstan 83 is installed vertically via a horizontal shaft 105 supported by the support support member 98 and is rotatable. It is supported. The uppermost part of the pull-out side capstan 83 is installed at the same height as the position of the die hole of the pull-out die 82, and the tube heat exchanger processed by the pull-out die 82 is wound along the outer peripheral surface thereof. There is.
The output shaft 106a of the drive motor 106 for rotary drive is installed so as to be directly connected to the horizontal shaft 105 on the side opposite to the side where the pull-out side capstan 83 is attached in the support column member 98, and the pull-out side capstan 83 is installed by the drive motor 106. Can be rotationally driven.

"Manufacturing method by the second manufacturing apparatus"
Next, an example of a method of manufacturing the tube heat exchanger 10 by using the manufacturing apparatus B configured as described above will be described.
The composite pipe 4 shown in FIG. 5 is prepared in advance (composite pipe preparation step).
In order to supply the composite base pipe 4 to the manufacturing apparatus B shown in FIGS. 8 to 10, the tip end side of the composite base pipe 4 is inserted from the inlet portion 88c of the hollow shaft portion 88 into the hollow shaft portion 88, and the hollow shaft portion is inserted. The composite raw pipe 4 is pulled out from the outlet portion 88d of 88, and is wound around the outer circumference of the unwinding side capstan 80 for one round as shown in FIG. The composite raw tube 4 is horizontally unwound from the unwinding side capstan 80 in the tangential direction, inserted into the die hole of the drawing die 82, and the composite raw tube 4 passed through the die hole of the drawing die 82 is passed through the drawing side capstan. Wrap it around the 83 for one round or more, and pull out the composite raw pipe 4 to the downstream side of the capstan 83 on the pull-out side. These operations are the work in the preparatory stage before the start of production of the tube heat exchanger 10.

After this preparatory work, the front end side and the rear end side of the composite raw tube 4 are covered with a tubular restraint 108 as shown in FIG. 9, and a thumbscrew is formed in a plurality of screw holes formed on the peripheral wall of the restraint 108. 108a is screwed to restrain the front end side and the rear end side of the composite raw tube 4. Next, as shown in FIG. 9, a spring-scale tension adjuster 109 provided with a coil spring for tension adjustment is connected to the restraint 108 on the front end side of the composite base pipe 4, and the restraint on the rear end side of the composite base pipe 4 is connected. A spring-scale tension adjuster 110 provided with a coil spring for tension adjustment is connected to the tool 108.

From this state, the processing of the composite raw tube 4 is started. Along with the start of processing, the composite raw tube 4 is sequentially moved at a constant speed to pass through the hollow shaft portion 88 and wound around the unwinding side capstan 80 (unwinding step). The pull-out force for passing the composite raw tube 4 through the pull-out die 82 is given by the rotational force of the pull-out side capstan 83 rotated by the drive motor 106.
The drawing die 82 is passed through the composite raw tube 4 unwound from the unwinding side capstan 80, wound around the pulling out side capstan 83, and unwound from the unwinding side capstan 83 at a constant speed. At the same time as starting these operations, the hollow shaft portion 88 is rotated at a predetermined speed by the drive motor 96, and the unwinding side capstan 80 and the weight body 93 are rotationally driven (twisting and pulling step).

Further, while monitoring the tension of the tension adjusting tools 109 and 110, the rear tension when the composite raw pipe 4 is wound around the unwinding side capstan 80 is adjusted to be constant.
Further, the forward tension when the composite raw pipe 4 is pulled out from the pull-out side capstan 80 is adjusted to be constant.
In order to stably apply the forward tension, a tensioning device such as a take-up roller or a winch device is placed on the downstream side of the tension adjusting tool 109, and the tension adjusting tool 109 is adjusted so that it can be towed at a constant speed. Is preferable. Further, in order to stably apply the rear tension, an unwinding device such as an unwinding roller is arranged on the upstream side of the tension adjusting tool 110, and the tension adjusting tool 110 is adjusted so that the tension adjusting tool 110 can be unwound at a constant speed. Is preferable.
Alternatively, the tension adjusters 109 and 110 are abbreviated, and a winding roller and a winding roller are arranged at these positions, and a brake mechanism and a speed adjusting mechanism are built in these rollers on the downstream side of the drawing die 82. Mass production is performed by applying a desired forward tension to the tip end side of the composite body tube 4 and applying a desired rearward tension to the rear end side of the composite body tube 4 on the upstream side of the drawing die 82. Above is preferred.

The die of the drawing die 82 from the unwinding side capstan 80 while applying an appropriate rear tension to the composite raw pipe 4 on the downstream side centering on the drawing die 82 and applying an appropriate rear tension to the composite raw pipe 4 on the upstream side. At the same time that the composite raw pipe 4 is passed through the hole, the unwinding side capstan 80 is rotated so that the composite raw pipe 4 passing through the die hole of the drawing die is simultaneously pulled out and twisted.
Usually, a thin raw tube made of aluminum or an aluminum alloy having an outer diameter of about 3 to 15 mm or about 3 to 10 mm is easily buckled or broken when only twisting is applied. In this manufacturing apparatus B, a pulling force is applied at the same time as a twisting force to pull out while suppressing breakage due to twisting. Therefore, even a composite raw tube 4 made of aluminum or an aluminum alloy having a small diameter of the above size is broken. Twist can be added without causing it.

As shown in FIG. 8, a region having a length L between the top position of the unwinding side capstan 80 and the contact position of the composite raw pipe 4 in the die hole of the drawing die 82 is defined as a twisting region of the composite raw pipe 4. To. In the manufacturing apparatus B, since the length L of this twisting region is made as short as possible, even if a large twisting angle is given to the composite raw pipe 4, the composite raw pipe 4 is not broken and is 5 ° to 80. It is possible to give a twist up to about ゜.

As shown in FIG. 10, the composite raw tube 4 is wound around the unwinding side capstan 80 for one round, so that the axial center is slightly deviated from the unwinding side axis C0 along the outer circumference of the unwinding side capstan 80. It is sent out along C1.
When the composite element tube 4 passes through the die hole of the drawing die 82, the center of the composite element tube 4 and the center of the die hole should be aligned so that extra stress does not act on the composite element tube 4. , The positional relationship of the hollow shaft portion 88 and the first position so that the unwinding side capstan 80 rotates around the axis C1 with the axis C1 on the unwound side from the unwinding side capstan 80 as the center of rotation. It is preferable to match the positional relationship of the support frame 90 with the positional relationship of the unwinding side capstan 80.
By aligning the center of the composite body tube 4 with the center of the die hole, a large twisting force is applied to the composite body tube 4 passing through the die hole, and the composite body tube 4 is processed with a large twist angle. It can be twisted without breaking 4.

The center of rotation for rotating the unwinding side capstan 80 coincides with the center of the hollow shaft portion 88, but this center of rotation is aligned with the center of the die hole of the drawing die 82 and is aligned with the center of the die. It is necessary to move the center of the composite base tube 4. Therefore, the composite raw tube 4 before being wound around the unwinding side capstan 80 rotates at a position slightly deviated from the axial center. Therefore, the composite raw tube 4 before being wound around the unwinding side capstan 80 will rotate eccentrically inside the hollow shaft portion 88, but the inner diameter of the hollow shaft portion 88 is a value that only absorbs this eccentric rotation. Since it is set to, there is no problem in the rotation of the composite raw tube 4.

As a result of being able to apply a large twisting force to the composite raw pipe 4 passing through the drawing die 82 by performing the twisting and pulling process described above, the composite raw pipe 4 is twisted in a spiral shape, and the twisting flow paths 10a, 10b, and 10d are formed. The tube heat exchanger 10 shown in FIG. 2 can be manufactured.

It will be described above that the tube heat exchanger 10 provided with the spiral flow path shown in FIGS. 2 and 3 can be manufactured by using the composite raw tube 4 having the structure shown in FIG. 5 and appropriately using the manufacturing devices A and B. did.
However, when the twist-pulling process is performed using the composite raw tube 4, the twist-pulling process is performed using the manufacturing apparatus shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2016-22505, which the applicant of the present application has previously applied for a patent. You may.
In this manufacturing apparatus, the drum and the unwinding side capstan are rotated along an axis orthogonal to the winding axis of the drum while unwinding the composite raw tube from the drum holding the coil in a coil shape and winding it around the unwinding side capstan. It is a device that can be used. Then, the raw pipe feeding process of unwinding the composite raw pipe from the unwinding side capstan while rotating it around the axis, and the pulling out side cap after pulling out the unwound composite raw pipe while reducing the diameter through a drawing die. It is a device that can be wrapped around a stun.
By using the manufacturing apparatus described in Japanese Patent Application Laid-Open No. 2016-22505 to twist and pull out the composite raw tube 4 described in the above embodiment, the tube heat having the structure shown in FIGS. 2 and 3 is obtained. The exchanger 10 may be manufactured.
As in the case of performing the twist-pulling process using the manufacturing device A described above, in order to perform the twist-pulling process in two steps, the composite raw tube 4 is passed through the manufacturing device B twice and the twist-pulling process is performed. It is good to apply. In that case, the size and diameter reduction ratio of the die holes of the drawing die used in the first torsional drawing process are appropriately changed, and the size and diameter reduction ratio of the die holes of the drawing die used in the second torsional drawing process are appropriately changed. It is preferable to adjust the twist angle to be finally obtained in the twist-pulling step.

According to the manufacturing method using the manufacturing apparatus A described in the above-described embodiment, the tube heat exchanger having the structure shown in FIGS. 11 and 12 was manufactured using the composite raw tube shown in the cross-sectional photograph of FIG.
The composite raw tube used was made of A3003 alloy, had an outer diameter of 10 mm and a wall thickness of 0.5 mm, and the obtained tube heat exchanger had an outer diameter of 8.4 mm and a twist angle of 25 °.
FIG. 12 is a photograph showing a state in which a part of the outer tube of the tube heat exchanger is peeled off and the side surface is exposed so that the twist angle and the spiral pitch given to the inner flow path tube can be seen. ..
It was found that a tube heat exchanger with a twist can be manufactured as shown in FIGS. 11 and 12.

Next, using the tube (made of A3003 alloy) of the first embodiment shown in FIG. 1, a tube heat exchanger in which the weld line lead angle (twist angle) is varied from 1.0 ° to 21.0 ° is used. It was prepared and subjected to a bending test in which it was bent 180 ° into a hairpin shape with a radius of curvature (R = 20). Each condition was evaluated under n = 20, and those in which cracks were observed on the outer peripheral surface of at least one tube heat exchanger were evaluated as x, and those in which no cracks were observed were evaluated as 〇. This hairpin bending test is performed as a kind of acceleration test for evaluating the bending workability of a tube heat exchanger.
To measure the twist angle of the weld line, each tube heat exchanger sample was immersed in a 5% sodium hydroxide aqueous solution at 50 ° C. for 1 minute, and the white streaks after etching were judged to be the weld line, and the twist angle was measured. ..

From the above description, using the manufacturing apparatus A having the above-described configuration, a tube heat exchanger having the twisted flow path shown in FIGS. 11 and 12 is manufactured by using a composite raw tube having a cross-sectional structure as shown in FIG. I found that I could do it.
It was also found that the twist angle of the weld line is preferably 10 ° or more.

Although various embodiments of the present invention have been described above, the configurations and combinations thereof in each embodiment are examples, and the configurations are added, omitted, replaced, and the configurations are added, omitted, replaced, and the like without departing from the spirit of the present invention. Other changes are possible. Further, the present invention is not limited to the embodiments.

INDUSTRIAL APPLICABILITY According to the present invention, it becomes possible to provide a tube heat exchanger made of aluminum or an aluminum alloy and having a twisted flow path inside. As a result, the cost, weight, and performance of the heat exchanger are reduced.

A, B ... Manufacturing equipment, 1 ... 1st drawing die, 2 ... 2nd drawing die, 4 ... Composite pipe, 5 ... Pipe material, 8 ... Inner pipe, 8A ... Flow pipe, 9 ... Outer pipe, 10 ... Tube type heat exchanger (multiple twisted tube), 10a ... First flow path (twisted flow path), 10b ... Second flow path (twisted flow path), 10C ... Intermediate twisted tube, 50 ... Tube type heat exchange Instrument (multiple twisted pipe), 51 ... outer pipe, 52 ... inner pipe, 54 ... first flow path (twisted flow path), 55 ... second flow path (twisted flow path), θ1 ... twist angle, WL ... Weld line, 80 ... Unwinding side capstan, 82 ... Pulling out die, 83 ... Pulling out side capstan.

Claims (5)

A metal tube heat exchanger in which the inner peripheral side of a hollow tube is composed of at least two or more flow paths and exchanges heat with a plurality of heat media flowing through these flow paths.
An outer pipe and an inner pipe housed inside the outer pipe are provided, and at least two or more flow paths are formed between the outer pipe and the inner pipe or inside the inner pipe, and these flow paths are formed in those flow paths. A constant twist angle is spirally provided in the longitudinal direction, and the metal or alloy constituting the outer tube and the metal or alloy constituting the inner tube are made of dissimilar metals or dissimilar alloys, and a constant twist is applied to the surface layer of the outer tube. A tubular heat exchanger characterized in that weld lines with horns are formed. The tube heat exchanger according to claim 1, wherein the hollow tube is twisted over the entire vertical cross section in the longitudinal direction, and the twist angle of the surface layer of the tube is 10 ° or more and 80 ° or less. .. The tube heat exchanger according to claim 1 or 2, wherein the twist angle of the weld line on the surface layer of the tube is 10 ° or more in the hollow tube. The tube heat exchanger according to any one of claims 1 to 3, wherein the tube heat exchanger is made of aluminum or an aluminum alloy. A metal tube heat exchanger in which the inner peripheral side of a hollow tube is composed of at least two or more flow paths and exchanges heat with a plurality of heat media flowing through the flow paths. In manufacturing a tube heat exchanger having a constant twist angle spirally in the longitudinal direction and a weld line having a constant twist angle on the surface layer of the tube.
The hollow tube is characterized in that it is manufactured from one or two or more extruded raw tubes, and after performing a composite process of simultaneously applying drawing and twisting to the hollow tube once or more, at a high temperature of 400 ° C. or higher. A method for manufacturing a tube heat exchanger, which comprises performing a heat treatment for 4 hours or more.

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