JP5993554B2 - Double tube and manufacturing method thereof - Google Patents

Description

  The present invention relates to a double tube used as a heat exchanger in which a spiral heat exchange passage is configured between an inner tube provided with a spiral uneven portion and an outer tube fitted to the inner tube. It belongs to the technical field.

  Recently, in a heat exchange system of an automobile air conditioner, etc., as a heat exchanger having a small size and high heat exchange efficiency, one fluid of heat exchange is circulated through a spiral heat exchange passage between an inner pipe and an outer pipe. Double pipes constructed in the above are widely used. In the double tube, a heat exchange passage is formed by forming a spiral uneven portion on the inner tube. For the formation of the concavo-convex portion of the inner tube, means for expanding the diameter of the straight elemental tube that becomes the inner tube in a spiral manner is partially employed. This diameter expansion process has the advantage that it is cheaper and easier to implement than a diameter reduction process means for partially reducing the diameter of a straight elemental pipe that becomes an inner pipe in a spiral shape.

  Conventionally, for example, a technique described in Patent Document 1 is known as a technique for forming a concavo-convex portion of an inner pipe of a double pipe by a diameter expanding process.

  In Patent Document 1, a straight element tube serving as an inner tube is set in a mold having concave and convex grooves, and a nozzle for supplying a pressure fluid is inserted into the element tube to apply pressure fluid. A technique for deforming an element tube along an uneven groove of a mold by pressure is described. In the concave / convex groove of the mold, the convex portion corresponds to the concave portion of the concave / convex portion of the inner tube (outer diameter of the raw tube), and the concave portion corresponds to the convex portion of the concave / convex portion of the inner tube (expanded portion of the raw tube). The nozzle has an annular packing such as an O-ring attached to the mounting groove formed in an annular shape on the outer periphery of the position on both sides of the length exceeding the diameter expansion range of the raw pipe in order to ensure the sealing performance of the pressure fluid. ing.

  The technique according to Patent Document 1 is intended for a synthetic resin inner tube (element tube) in which a non-spiral concavo-convex part is formed. For example, the present invention can also be applied to the case where a spiral concavo-convex portion is formed on an aluminum-based metal inner tube that is frequently used as a heat exchanger material.

JP 2011-31579 A

  In the above-mentioned double pipe, the inner pipe and the outer pipe are brazed at both ends of the outer pipe in order to close the opening to the outside of the spiral heat exchange passage formed between the inner pipe and the outer pipe. Sealing by caulking is necessary, but there is a large difference between the inner tube diameter (element tube diameter) and the outer tube diameter corresponding to the convex portion of the concave and convex portions of the inner tube. There is a problem that it is.

  The present invention has been made in consideration of such problems, and can be easily sealed to close the opening to the outside of the spiral heat exchange passage formed between the inner tube and the outer tube. It is an object of the present invention to provide a double pipe and a method for producing a double pipe suitable for producing the double pipe.

In order to solve the above-described problems, the double pipe according to the present invention employs the means described in claim 1 of the claims.

That is, in claim 1, the heat exchange passage through which one outer fluid is circulated between the inner tube and the outer tube by fitting the outer tube to the inner tube formed with the expanded spiral uneven portion. In a double pipe configured to close the opening of the heat exchange passage to the outside at both ends of the outer pipe, an annular shape that is in contact with the inner peripheral surface of the outer pipe at a position facing both ends of the outer pipe of the inner pipe The closing projections of the inner pipe are provided with at least two closing projections in the axial direction with a slight gap, and an annular packing is mounted between the closing projections of the inner tube . It is characterized by that.

In this means, the closing convex portion of the inner pipe is brought into contact with the inner peripheral surface of the outer pipe to fill the difference between the diameters of the inner pipe and the outer pipe, so that the closing convex portion of the inner pipe is arranged at both end portions of the outer pipe. It functions as a temporary seal structure and a basic structure for seal processing. Further, by providing a gap between the two closing convex portions of the inner tube, it becomes possible to reliably attach the annular packing between the closing convex portions.

In order to solve the above-mentioned problems, the method according to the present invention employs the means described in claims 2 and 3 of the claims.

That is, in claim 2 , while setting the straight elemental tube to be the inner tube in a mold in which a spiral concave and convex groove is formed, a nozzle to which a pressure fluid is supplied is inserted into the inner tube, One of the heat exchanges between the outer tube fitted to the inner tube in which the spiral tube is formed by deforming the base tube along the uneven groove of the mold by pressurizing the pressure fluid, and the spiral uneven portion is formed by the diameter expansion process. In the manufacturing method of the double pipe that constitutes the heat exchange passage through which the fluid flows, an annular groove is formed at a position where the inner pipe of the mold faces both ends of the outer pipe, and the pressure fluid The inner tube is deformed along the concave groove of the mold by pressurizing the inner tube, and the inner tube is fitted to the inner peripheral surface of both ends of the outer tube fitted with the inner tube formed with the annular closing convex portion by the diameter expansion process. An annular closing convex portion of the tube is brought into contact with the tube.

  With this means, the diameter difference between the inner pipe and the outer pipe is compensated by the diameter expansion process of the pressure fluid, which is the same means as the formation of the spiral uneven portion of the inner pipe, to contact the inner peripheral surface of the outer pipe. Protrusions for closing the inner tube functioning as a temporary seal structure and a basic structure for sealing at both ends of the outer tube are formed.

That is, in claim 3, in the manufacturing method of the double tube according to claim 2, uneven portions of the inner tube, the closing convex part characterized by being formed simultaneously by common pressure fluid by a common nozzle.

  With this means, the concave and convex portions of the inner tube and the convex portions for closing are formed at the same time.

In the double pipe according to the present invention, the closing convex part of the inner pipe is closed by contacting the inner peripheral surface of the outer pipe with the closing convex part of the inner pipe to fill the difference in diameter between the inner pipe and the outer pipe. Since it functions as a temporary seal structure at both ends of the outer tube and a basic structure for sealing, brazing and caulking can be carried out using the projections for closing the inner tube. There is an effect that the sealing process for closing the opening to the outside of the spiral heat exchange passage formed therebetween is facilitated. In addition, since a gap is provided between the two closing projections of the inner tube, it is possible to securely attach an annular packing between the closing projections, so that sealing is performed by caulking. In this case, the sealing performance is improved.

  Further, the manufacturing method of the double pipe according to the present invention is a method in which the inner pipe is brought into contact with the inner peripheral surface of the outer pipe by the diameter expansion process of the pressure fluid, which is the same means as the formation of the spiral uneven portion of the inner pipe. , Since the inner pipe closing convex part that functions as a temporary seal structure and the basic structure of the sealing process is formed at both ends of the outer pipe by filling the difference in the diameter of the outer pipe, additional equipment and processing are required. However, there is an effect that the double pipe can be manufactured inexpensively and easily.

Furthermore, as claimed in claim 3 , since the concave and convex portions of the inner tube and the convex portions for closing are formed at the same time, there is an effect suitable for mass production.

It is sectional drawing of manufacture of the 1st example of the form for enforcing the double pipe concerning the invention, and its manufacturing method, and a manufacturing process is shown in order of (A)-(C). FIG. 2 is an enlarged side view of FIG. It is an expanded sectional view of the principal part of the last process of manufacture following Drawing 1 (C), and different seal processing is shown in (A) and (B). It is sectional drawing of manufacture of the 2nd example of the form for implementing the double tube | pipe which concerns on invention, and its manufacturing method. It is sectional drawing of manufacture of the 3rd example of the form for implementing the double pipe | tube which concerns on this invention, and its manufacturing method, and a manufacturing process is shown in order of (A) and (B).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out a double pipe and a method for producing the same according to the present invention will be described with reference to the drawings.

  1 to 3 show a first example of a form for carrying out a double pipe and a manufacturing method thereof according to the present invention.

  In the first example, one suitable for sealing the inner tube 1 and the outer tube 2 made of an aluminum metal material by brazing is shown.

  A first example will be described based on a manufacturing example of a double tube.

  This production example basically uses the technique according to Patent Document 1.

  First, as shown in FIG. 1A, a straight element tube 1A to be an inner tube 1 is set in a mold 3, and a nozzle 4 to which a pressure fluid P is supplied is inserted into the element tube 1A.

  The mold 3 has a spiral concave-convex groove in which a main body groove 31 having a circular cross section corresponding to the outer diameter of the base tube 1A is penetrated in the axial direction, and is further dug from the main body groove 31 in the central portion of the main body groove 31 in the axial direction. 32 are provided at both ends in the axial direction of the main body groove 31, respectively, and annular concave grooves 33 that are further dug from the main body groove 31 with a slight gap therebetween. The depth (diameter) of the concave and convex grooves 32 and 33 including the main body groove 31 is set to correspond to the inner diameter of the outer tube 2. In the concave / convex groove 32, the convex portion uses the main body groove 31 as it is, and only the concave portion is dug. Further, the concave groove 33 is set so as to be positioned in the vicinity of both end portions of the outer tube 2. Further, as shown in FIG. 2, the mold 3 is provided with four parting lines 34 radially from the axial center, and is opened and closed with four parts in the radial direction.

  The nozzle 4 is formed of a metal rod having an outer diameter slightly smaller than the inner diameter of the raw tube 1A, and the tip 41 is formed in a hemispherical shape so as not to damage the raw tube 1A during insertion. An annular mounting groove 44 to which an annular packing 43 such as an O-ring is attached is engraved at a position slightly closer to the rear end portion 42 from the front end portion 41 and a position closer to the rear end portion 42 longer than the front end portion 41. A pressure fluid supply passage 45 for supplying the pressure fluid P from the rear end portion 42 in the central axial direction is disposed, and communicated with the pressure fluid supply passage 45 between the mounting grooves 44 on the outer peripheral surface to discharge the pressure fluid P. A discharge port 46 is opened. The interval between both mounting grooves 44 (packing 43) is set longer than the interval between the concave grooves 33 of the mold 3.

  In the state shown in FIG. 1A, both mounting grooves 44 (packing 43) of the nozzle 4 inserted into the raw tube 1 </ b> A held by the mold 3 that is closed are the concave and convex grooves 32 of the mold 3. , Are disposed outside the groove 33 in the axial direction.

  Next, as shown in FIG. 1B, a pressure fluid P such as oil is supplied from the rear end of the nozzle 4.

  As a result, the space in which the pressure fluid P discharged from the discharge port 46 via the pressure fluid supply path 44 of the nozzle 4 is surrounded by the inner peripheral surface of the raw tube 1 </ b> A, the outer peripheral surface of the nozzle 4, and the packing 43 of the nozzle 4. The raw tube 1A is deformed so as to follow the concave and convex grooves 32 and 33 of the mold 3. That is, a part of the raw tube 1A is subjected to a diameter expansion process, and a spiral concavo-convex portion 11 corresponding to the concavo-convex groove 32 of the mold 3 and an annular closing convex portion 12 corresponding to the concave groove 33 of the mold 3 are formed. The formed inner tube 1 is formed.

  Next, the nozzle 4 is pulled out from the inner tube 1 to open the mold 3. At this time, since the mold 3 is opened and closed by four parts in the radial direction, the spiral concavo-convex portion 11 of the inner tube 1 does not obstruct the removal of the mold 3. If necessary, the pressure fluid P is discharged before and after the mold 3 is opened, or the pressure fluid P is discharged using cleaning of the inner tube 1 before fitting with the outer tube 2 described later. .

  Next, as shown in FIG. 1C, the inner tube 1 is fitted inside the outer tube 2.

  As a result, the uneven portion 11 and the closing convex portion 12 of the inner tube 1 are brought into contact with the inner peripheral surface of the outer tube 2. Therefore, between the inner tube 1 and the outer tube, a spiral heat exchange passage 5 through which one fluid for heat exchange flows is formed in the uneven portion 11 of the inner tube 1, and the convex for closing the inner tube 1 is formed. The both ends of the heat exchange passage 5 are temporarily sealed at both ends of the outer tube 2 that is the portion 12.

  Thereafter, as shown in FIG. 3 (A), when the brazing material 6 formed in an annular shape is fitted to the inner tube 1 and brought into contact with the end of the outer tube 2, the projection 12 for closing the inner tube 1 is closed. The brazing material 6 can be held stably by serving as a seat for the brazing material 6.

  Thus, as shown in FIG. 3B, when the brazing material 6 is heated and melted, the brazing material 6 adheres securely to the closing convex portion 12 of the inner tube 1 and the outer tube 2 without flowing to the surroundings.

  According to the first example, even if there is a large difference between the diameter of the inner tube 1 and the diameter of the outer tube 2, the outside of the spiral heat exchange passage 5 formed between the inner tube 1 and the outer tube 2. The sealing process by brazing to close the opening to can be easily performed. For this purpose, the inner tube 1 is provided with a closing convex portion 12. However, since the inner tube 1 is formed at the same time by the same diameter expansion process as the concave and convex portion 11 of the inner tube 1, the double tube can be made inexpensively and easily. It can be manufactured and is also suitable for mass production.

  FIG. 4 shows a second example of the embodiment for carrying out the double pipe and the manufacturing method thereof according to the present invention.

  In the second example, the structure of the nozzle 4 of the first example is changed.

  In the nozzle 4 of the second example, the mounting groove 44 (packing 43) is added so as to separately surround the concave and convex grooves 32 and 33 of the mold 3 of the mold 3, and the pressure fluid P corresponding to the expansion is provided. Are respectively opened.

  According to the second example, the pressure fluid P is reliably applied to the raw tube 1A corresponding to the concave and convex grooves 32 and the concave grooves 33 of the mold 3 of the mold 3, and the concave and convex portions 11 and the convex portions for closing are formed on the inner tube 1. 12 can be formed accurately and at high speed.

  FIG. 5 shows a third example of the embodiment for carrying out the double pipe and the manufacturing method thereof according to the present invention.

  In the third example, two projections 12 for closing the inner tube 1 are provided in the axial direction with a slight gap therebetween.

In the third example, as shown in FIG. 5 (A), mounting the annular packing 7 such as an O-ring on the closure projection 12 when fitting the inner tube 1 to the outer tube 2. The packing 7 mounted between the two closing convex portions 12 of the inner tube 1 is securely held and does not easily come off. Then, as shown in FIG. 5 (B), comprising an end portion of the outer tube 2 to be caulked.

  According to the third example, even if there is a large difference between the diameter of the inner pipe 1 and the diameter of the outer pipe 2, the outside of the spiral heat exchange passage 5 formed between the inner pipe 1 and the outer pipe 2. Sealing with caulking to close the opening to the can be easily performed. For this reason, the inner tube 1 is provided with two closing projections 12 each. However, since the inner tube 1 is formed simultaneously with the concavo-convex portion 11 of the inner tube 1 by a diameter expansion process, the double tube is inexpensive. , It can be easily manufactured and is suitable for mass production.

  As described above, in addition to the illustrated examples, it is also possible to form three or more chain protrusions 12 of the inner tube 1 of the third example and provide two or more packings 7.

  The double pipe and the manufacturing method thereof according to the present invention can be applied to a double pipe composed of an inner pipe and an outer pipe made of a material other than an aluminum-based metal material.

DESCRIPTION OF SYMBOLS 1 Inner tube 1A Elementary tube 11 Concave portion 12 Convex portion 2 Closure 2 Outer tube 3 Mold 31 Body groove 32 Concave groove 33 Concave groove 4 Nozzle 5 Heat exchange passage P Pressure fluid

Claims (3)

A heat exchange passage is formed in which the outer pipe is fitted to the inner pipe formed with the expanded spiral concave and convex portion, and one fluid for heat exchange flows between the inner pipe and the outer pipe. In the double pipe that closes the heat exchange passage to the outside at the part, an annular closing convex part that contacts the inner peripheral surface of the outer pipe is formed at a position facing both ends of the outer pipe of the inner pipe And at least two projections for closing the inner tube are provided with a small gap in the axial direction, and an annular packing is mounted between the projections for closing the inner tube. tube.   Set the straight elemental tube that will be the inner tube in the mold with spiral concave and convex grooves, and insert the nozzle that supplies the pressure fluid into the element tube and pressurize the element by pressurizing the pressure fluid. Heat exchange in which one fluid of heat exchange flows between the outer tube fitted to the inner tube in which the tube is deformed along the uneven groove of the mold and the spiral uneven portion is formed by the diameter expansion process In the manufacturing method of the double pipe constituting the passage, an annular concave groove is formed at a position where the inner pipe of the mold faces both ends of the outer pipe, and the raw pipe is removed by pressurizing the pressure fluid. The inner tube annular projections are formed on the inner peripheral surfaces of both ends of the outer tube which are deformed along the concave grooves of the mold and fitted into the inner tube formed with the annular projections by the diameter expansion process. A method of manufacturing a double pipe, wherein the parts are brought into contact with each other.   3. The method of manufacturing a double pipe according to claim 2, wherein the uneven portion and the closing convex portion of the inner tube are simultaneously formed by a common pressure fluid from a common nozzle.

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