JPH0586285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates primarily to a method of manufacturing a metal tube with spiral fins used as a crusher screen tube or the like.

[Problems to be solved by conventional technology and invention]

Generally, methods for forming fins in metal tubes with spiral fins include welding and fixing the fins;
Alternatively, a method of forming fins by rolling is conventionally known.

FIG. 8 is a perspective view showing a conventional method (Japanese Unexamined Patent Publication No. 58-9715) for forming a spiral fin by welding and fixing, in the width direction of the strip material 16 forming the spiral fin on the outer periphery of the metal pipe _P0 . The spiral fin 15 is formed by wrapping one side edge in a spiral shape at a predetermined pitch and fixing it by welding.

Figure 9 A shows the conventional method of forming spiral fins (Plasticity and Processing Vol.10 No.105 1969-10)
A schematic front view showing the
This is an enlarged cross-sectional view taken along a line, in which three rolling rolls 21, 22, and 23 are pressed and rolled on the outer periphery of a metal pipe _P0 to form a spiral fin 25.

Each of the rolling rolls 21, 22, and 23 is constructed by mounting on a single shaft several dozen day scrolls each having a thin disk shape and a wedge-shaped cross-sectional shape on the outer periphery _. A substantially U-shaped groove is formed on the outer surface of the groove by rolling down force in the thickness direction, and the depth is increased by the force acting perpendicularly to the groove surface, and the metal displaced by this groove processing is removed. A spiral fin 25 is formed by moving it into the gap between the rolling rolls 21, 22, and 23.

Figure 10A is a schematic front view of another conventional method for rolling spiral fins (Japanese Unexamined Patent Publication No. 124023/1983), and Figure 10B is the - of Figure 10A.
This is an enlarged cross-sectional view taken along a line, showing a metal pipe P ₀ with a mandrel bar 36 passed through it, and three rolling rolls 31, 3 each having a plurality of annular grooves 34 on the circumferential surface.
Hot rolling is carried out using an inclined rolling mill having a diameter of 2 and 33 to produce a metal flow toward the inside of the annular groove 34, thereby forming a spiral fin.

Incidentally, spiral fins for crusher screw tubes generally require a predetermined fin height, fin pitch, and fin inclination angle.

Therefore, when applying the first method to manufacture a crushing screw tube, the strip material 1
6 must be welded in an inclined position, resulting in extremely poor work efficiency.

Further, in the second method, the metal displaced by the disk rolls is made to stand up between the disk rolls, so the fin pitch is large and it is difficult to form the fin bottoms into flat surfaces. Furthermore, the third
Although the method described above allows relatively easy setting of the fin height and fin pitch, it does not take into consideration the setting of the fin inclination angle.

Incidentally, as a method of setting the inclination angle of the spiral fin, the method shown in FIGS. 11 and 12 is conventionally known.

FIG. 11 is an explanatory diagram showing a conventional method of setting a spiral groove or threaded portion formed on the outer circumferential surface of a metal pipe P ₀ to a predetermined inclination angle. First, as shown in FIG. 11A, After forming trapezoidal threaded portions 45 on the outer periphery of the metal pipe P ₀ by machining or the like, the side surfaces thereof are inclined by θ ₁ and θ ₁ from positions orthogonal to the groove bottom surface, respectively. The top surface of the peak portion 45 and one tapered surface 45a are brought into contact with each other, so that the tapered surface 45a is formed to have a negative inclination angle as shown in FIG. 11B.

However, this method has a problem in that it requires two steps: forming the spiral threaded portion 45 and setting the side surface 45a of the threaded portion 45 at a predetermined angle.

FIG. 12 is an explanatory diagram of a conventional method for manufacturing boiling heat exchanger tubes, in which a roller 51 equipped with a plurality of disks separated by spacers is pressed onto the outer periphery of a metal tube P ₀ into which a mandrel (not shown) is inserted. It's starting to feel like it's forcing me. Each disk in the roller 51 has a pressing surface 5 whose inclination angle with respect to the peripheral surface of the metal tube increases as it goes toward the exit side of the metal tube _P0 .
1a, and after forming a spiral fin 55 near the entrance side of the metal pipe _P0 , it is sequentially bent at an angle on the pressing surface 51a, and finally a small hole closed inside is formed. This is a method for manufacturing boiling heat exchanger tubes.

However, although this method can simultaneously form the spiral fins and incline the spiral fins, the distance between the formed spiral fins 55 is narrow as in the case shown in FIG. 9, and the distance between the bottoms of the spiral fins is wide. It is not possible to increase the interval between the spiral fins, and the inclination angle of the spiral fins is determined by setting the angle of the pressing surface 51a of the roller-shaped disk, which causes problems such as the inability to set the angle accurately.

The present invention has been made in view of the above circumstances, and its purpose is to create a large hole by hot perforating or diameter-expanding rolling a solid metal rod or metal tube using an inclined rolling mill. To provide a method for manufacturing a metal tube with spiral fins, which allows forming spiral fins with a high pitch at a required angle of inclination to the outer circumferential surface of the tube.

[Means to solve the problem]

A method for manufacturing a metal tube with spiral fins according to the first invention is a method for manufacturing a metal tube with spiral fins by using an inclined rolling mill having three or four rolling rolls having a plurality of annular grooves in the circumferential direction of the outer peripheral surface and a piercing plug. In a method for manufacturing a metal tube with a spiral fin by hot perforation or diameter expansion rolling of a metal rod or metal tube, the depth direction of the annular groove of each of the rolling rolls with respect to the pass line of the solid metal rod or metal tube. Using a rolling roll whose angle is approximately perpendicular on the entrance side of a solid metal rod or metal tube and inclined at a predetermined angle on the exit side, the spiral fin is made perpendicular to the tube axis on the entrance side. After forming, the spiral fin is inclined from its base toward the tube axis toward the exit side.

A method for manufacturing a metal tube with a spiral fin according to the second invention includes: a pair of rolling rolls having a plurality of annular grooves in the circumferential direction on the outer peripheral surface; a pair of non-rotating guide shafts having a groove on the side opposite to the pass line; and hot perforation or diameter expansion rolling of a solid metal rod or metal tube using an inclined rolling mill equipped with a perforation plug,
In a method for manufacturing a metal tube with a spiral fin, the angle in the depth direction of each of the annular groove of the rolling roll and the groove of the non-rotating guide shaft with respect to the pass line of the solid metal rod or metal tube is adjusted to After forming a spiral fin in a state that is approximately perpendicular to the tube axis near the entrance side and upright to the pipe axis near the entrance side using rolling rolls and a non-rotating guide shaft that are tilted at a predetermined angle near the exit side, It is characterized in that the spiral fin is inclined from its base with respect to the tube axis toward the side.

[Effect]

According to the method of the present invention, in one step,
It is possible to form a spiral fin with a predetermined height, pitch, and inclination angle.

〔Example〕

The present invention will be specifically explained below based on the drawings.
FIG. 1 is a schematic front view (the grooves of the rolling rolls are omitted) showing the implementation state of the method for manufacturing a metal tube with spiral fins according to the present invention (hereinafter referred to as the method of the present invention), and FIG. This is an enlarged cross-sectional view taken along the line - in FIG. 1, in which B indicates a solid metal bar with a circular cross section as the raw material, and 10 indicates an inclined rolling mill arranged facing the pass line of the solid metal bar B. There is.

The inclined rolling mill 10 has pass line - 3 around the line.
It includes three rolling rolls 1, 2, and 3 at equally spaced positions, and a plug 6 supported by a mandrel 6a along a pass line.

Each of the rolling rolls 1, 2, and 3 is supported at both ends thereof, and is driven to rotate in the same direction (directions of arrows a, b, and c) by a drive source (not shown).

Each rolling roll 1, 2, 3 has the same surface angle α ₁ ,
α ₂ is provided on the input and exit sides, and the shaft ends on the same side are inclined toward the same side in the circumferential direction (the inclination angle β of the roll axis with respect to the pass line is called the inclination angle). and the shaft end on the same side is inclined so that it approaches or moves away from the pass line side (crossing angle γ of the roll axis with respect to the pass line)
is called the crossing angle, and the angle γ in the direction in which the roll axis separates from the pass line on the exit side is defined as positive).

A plurality of annular grooves 4, for example, 5 to 7 grooves, are cut in the circumferential direction at appropriate lengths apart in the axial direction on the outer peripheral surfaces of the rolling rolls 1, 2, and 3. The phase between the rolls 1, 2, and 3 is shifted by 120° with respect to the rotation of the solid metal rod B. Regarding the processing of this annular groove 4, the groove may be formed by cutting on the outer periphery of an integral roll, or the annular groove may be formed by combining a day scroll and a spacer and supporting it on one shaft. . The formation position, formation interval, etc. of this annular groove 4 differ between rolling rolls, as partially shown in Fig. The angles are made different from the inlet side to the outlet side of the solid metal rod B.

Depending on the height, interval, inclination angle, and plug shape of the spiral fins to be formed, the position, interval, and angle of the annular groove 4 with respect to the groove depth direction are determined, and the rolling rolls 1,
A few of the angles α, β, γ, etc. are determined. The formation position and depth of the annular groove 4 are determined from the input side to the output side of the rolled material, taking into account the spiral metal flow during inclined rolling and the metal flow toward the fin side formed in the gap between the rolling roll grooves. Changes have been made as appropriate to achieve this.

As shown in FIG. 2, the annular groove 4 formed near the entry side of the solid metal rod
The angle in the depth direction of the annular groove 4 is approximately a right angle, whereas the annular groove 4b formed closer to the exit side
The angle in the depth direction with respect to the pass line is not perpendicular but oblique.

The angle between the depth direction of the annular groove 4b and the mill roll axis is set based on the inclination angle of the spiral fin to be manufactured and the intersecting angle γ of the mill rolls 1, 2, and 3.

As a result, the spiral fin coming out of one rolling roll is guided to the annular groove 4 of the next rolling roll, and an upright spiral fin is formed one after another, and at the exit side, this spiral fin is pushed down from its root. A spiral fin 5 having a predetermined inclination angle is formed.

The plug 6 is bullet-shaped, has its base end supported by the tip of the mandrel 6a, and is disposed on the pass line of the solid metal rod B and the metal tube P with spiral fins.

After heating the solid metal rod B with a circular cross section to a predetermined temperature, it is fed from the direction of arrow d to an inclined type piercing rolling mill having the above-mentioned configuration, and the rolling rolls 1,
Let it bite in between 2-3 minutes. Rolls 1, 2, 3
The solid metal rod B, which is bitten by When the plug 6 is penetrated along the line, a strain component is applied by the plug 6 in the radial direction of the solid metal rod B from the inner surface side, and the annular groove 4 in the rolling rolls 1, 2, 3 is easily The metal flows in the depth direction, and the outer diameter of the spiral fin 5 is formed to be larger than the outer diameter of the solid metal rod B.

The ratio of the spiral fin outer diameter of the spiral fin-equipped metal pipe P to the diameter of the solid metal rod B (referred to as the tube expansion ratio) is usually 1.5 to maintain stable operation.
The following is desirable.

In addition, in a pass schedule with an expansion ratio exceeding 1.5, the plug diameter becomes large and the passing resistance becomes high, making it difficult for the material to come off stably at the end of rolling, which may result in damage to the spiral fin, and damage to the spiral fin outer periphery. This is because if the circumferential stretching of the fin is excessive and the material has poor workability, troubles such as cracks will occur at the fin peripheral edge.

The above case is described in detail for the case where the number of rolling rolls is 3, but even when the number of rolling rolls is 4, the 4 rolling rolls are equally distributed around the pass line, and the grooves are processed by each rolling roll. By shifting the phase by 90 degrees with respect to the rotation of the solid metal rod between
A similar method can be achieved.

By the way, when configuring an inclined rolling mill with five or more rolling rolls, the diameter of the rolling rolls cannot be made much larger than the diameter of the solid metal rod due to geometrical problems, so the rolling roll shafts must be supported at both ends. It becomes difficult to do so. Furthermore, since the diameter of the rolling roll shaft is small, the rigidity of the roll shaft is also reduced, and dimensional fluctuations due to material temperature fluctuations become large. Furthermore, since the diameter of the rolling roll is small, the rolling speed becomes slow, making it impossible to obtain sufficient production efficiency. For the above reasons, the number of rolling rolls that make up the inclined rolling mill is 4.
Limited to no more than 1.

FIG. 3 is a schematic front view showing another embodiment of the present invention (the grooves of the rolling rolls are omitted), FIG. 4 is an enlarged sectional view taken along the - line in FIG. 3, and FIG. It is a perspective view of two guide shoes used in a rolling mill, and in the figure, the same numbers and symbols as those shown in FIGS. 1 and 2 indicate the same parts.

The tilt rolling mill is similar to ordinary Mannesmann type seamless pipe manufacturing equipment (piercer), with two rolling rolls 1 and 2 arranged at two equal positions around the pass line, and a rolling mill between them. Arranged guide shoe 8
a, 8b and a plug 6. An annular groove 4 is formed on the outer peripheral surfaces of the two rolling rolls 1 and 2, and a groove 9 is formed on the surface of the guide shoes 8a and 8b.

Annular grooves 4 are formed in the rolling rolls 1 and 2 so as to be 180° out of phase with respect to the direction of rotation of the solid metal rod B. On the other hand, the guide shafts 8a and 8b are formed with grooves 9 that match the direction of spiral progress of the spiral fins that are gradually formed in the process of rolling the solid metal rod B, and the spiral fins that have come out from the previous rolling rolls. When the fins enter the grooves of the adjacent guide shaft, they are not crushed and instead enter the grooves of the next rolling roll.

As in the case shown in Figs. 1 and 2, the annular groove 4 formed near the entrance side of the rolling mill is arranged so that its depth direction is approximately perpendicular to the pass line, and the annular groove 4 is formed near the exit side of the rolling mill. The depth direction of the formed annular groove 4b is not perpendicular to the pass line but is oblique.

While piercing and rolling the solid metal rod B, the annular grooves 4 of the rolling rolls 1, 2, and 3 are filled with metal to gradually form a spiral fin, and the formed spiral fin is moved toward the exit side. By pressing down from the root in the tube axis direction through the annular groove 4b, a metal tube with a spiral fin having the spiral fin 5 inclined at a required angle can be easily manufactured.

FIG. 6 is a schematic plan view showing still another embodiment of the present invention (the grooves of the rolling rolls are omitted), and FIG. 7 is an enlarged sectional view taken along the line - in FIG. The same numbers and symbols as in Figures 1 and 2 indicate the same parts.

In the figure, P ₀ is a metal blank pipe as a material to be rolled, with a small-diameter pilot hole 5b bored in the center, and in this example, this metal blank pipe P ₀ is used as a rolled material.
use. Note that the annular grooves 4 formed on the outer circumferential surfaces of the rolling rolls 1, 2, and 3 are the same as those shown in FIGS. 1 and 2.

After heating the metal blank P ₀ to a predetermined temperature (for example, 1200° in the case of medium carbon steel) in a heating furnace (not shown), it is transferred from the direction of arrow d to an inclined rolling mill, and the metal blank is rolled by the inclined rolling mill. The pipe P ₀ is pierced and rolled to expand its diameter as shown in FIG.

That is, when rolling of the metal tube P ₀ is started in the inclined rolling mill, the metal tube P ₀ is rolled by the rolling rolls 1, 2,
3 and is rolled at three locations in the circumferential direction, and the diameter of the lower hole 8 is enlarged by the plug 6 to perform piercing rolling. The metal of the metal tube P ₀ flows in its radial direction and fills the annular grooves 4 of each rolling roll 1, 2, and 3, resulting in a desired height from the metal tube P ₀ .
A spiral fin 5 having a pitch and an inclination angle is obtained.

In addition, it is desirable that the diameter of the pilot hole 8 of the metal pipe P ₀ is 1/2 or less of the maximum diameter of the plug 6. This is because if the diameter of the pilot hole 8 becomes large, a sufficient strain component in the radial direction from the tube axis will not be applied, and the tube wall will not fill the rolling roll groove, making it difficult to manufacture a high spiral fin.

In the cases shown in Figs. 3, 4, and 5, instead of the solid metal rod B as the material to be rolled, a metal pipe P ₀ is used.
It goes without saying that a metal tube with spiral fins can be manufactured in exactly the same manner using the above method.

In addition, the roll design method is basically the same whether forming a multi-filament spiral fin or a single-filament spiral fin.
In the case of a strip, the annular groove 4 of each rolling roll is designed to advance one pitch each time the material to be rolled rotates once, whereas in the case of two or three strips, the annular groove 4 of each roll advances one pitch each time the material to be rolled rotates once. The annular groove 4 of each rolling roll is 2 pitches each,
It is designed to advance 3 pitches. Of course, the inclination angle β of the rolling rolls is appropriately set depending on the progress pitch of rolling.

In this case, since a plurality of spiral fins can be formed simultaneously, the production speed is increased and the production efficiency is dramatically improved.

In addition, when manufacturing metal tubes with spiral fins, the plug 6 may suffer significant erosion, but if multiple spiral fins are formed in parallel at the same time, even if the rolling rolls are at the same rotation speed, the rolling Since the speed can be doubled, tripled, etc., the rolling time can be reduced to 1/2, 1/3, etc., and the contact time between the plug and the rolled material is shortened.
Plug life can be extended.

A specific numerical example will be explained below.

[Numerical example 1] A solid metal rod made of S45C with a circular cross section (outer diameter
70mm) by hot rolling, and this was
A metal tube with spiral fins having the following dimensional specifications was manufactured using an inclined rolling mill having three rolling rolls each having a plurality of annular grooves 4 formed on the circumferential surface as shown in FIG.

Fin pitch: 50mm Fin outer diameter: 90mm Bottom diameter between fins: 50mm Inner diameter: 36mm Fin inclination angle: 60° to the tube axis (in other words, the vertical fins are tilted 30°) The conditions of the inclined rolling mill at this time, especially The conditions of the rolling rolls are as follows.

Roll material: SCM440 Roll inlet rolling surface angle α ₁ : 3 degrees Roll inclination angle β: 16° Roll exit flank angle α ₂ : 2° Roll crossing angle γ: 2° Angle of annular groove on the roll end face on the exit side of the inclined rolling mill : 30° Maximum roll diameter: 200 mm Solid metal rod heating temperature: 1150°C As a result, the above spiral fin tube was easily produced.

[Numerical Example 2] A spiral fin-equipped metal tube having the same dimensional specifications as [Numerical Example 1] was prepared as shown in Figures 3 to 5.
It was manufactured using an inclined rolling mill equipped with two rolling rolls. The conditions of the inclined rolling mill at this time, particularly the conditions of the rolling rolls, are as follows.

Roll material: SCM440 Roll inlet draft angle α ₁ : 3.5° Roll inclination angle β: 16° Roll exit flank angle α ₂ : 3.5° Roll intersection angle γ: 2° Guide system: Plate guide system (with grooves) Roll maximum Part diameter: 500 mm As a result, a metal tube with spiral fins similar to [Numerical Example 1] could be manufactured.

In addition, in the case of an inclined rolling mill equipped with two rolling rolls as shown in Figs. 2 to 5, there is no geometric limit on the rolling roll diameter, so the roll diameter can be increased (from 200 mm to 500 mm). It becomes easy to increase the rolling speed. On the other hand, guide shoes 8a, 8b
Due to the friction between the rolled material and the guide shoes 8a and 8b, tool flaws and seizure may occur depending on the material of the rolled material, as shown in Figures 1 and 2. There are advantages and disadvantages between this case and the cases shown in FIGS. 3 to 5.

[Numerical example 3] In order to obtain a metal tube with spiral fins having the same dimensional specifications as [Numerical example 1], the outer diameter is 70 mm and the inner diameter is 10 mm.
The 6th and 7th metal pipes (made of S45) with small holes of mm
It was manufactured using an inclined rolling mill as shown in the figure.

Of course, when designing the roll, the presence of small holes was taken into consideration, and the groove pitch was varied from the rolling mill entry side to the rolling mill exit side.

As a result, the same effects as in Numerical Examples 1 and 2 were obtained.

〔Effect of the invention〕

In the first invention, a solid metal rod or metal tube is hot-pierced or Due to diameter expansion rolling, solid metal rods and metal tubes are subjected to a strong pressing force from the inside to the outside by the plugs in addition to the pressing force from the rolling rolls from the outside surface, and the material of the solid metal rods and metal tubes is Regardless of the method, a large metal flow in the radial direction can be generated, making it possible to form a tall spiral fin with a small pitch.

In addition, in the second invention, a solid metal rod or metal tube is hot-rolled using an inclined rolling mill that combines a pair of rolling rolls having a plurality of annular grooves, a pair of non-rotating guide shoes, and a piercing plug. Since the material is perforated or rolled to expand its diameter, it is possible to form a spiral fin without being limited by the diameter of the solid metal rod or metal tube.

Furthermore, in the first and second inventions, by using a roll whose depth direction angle of the annular groove is approximately vertical on the entry side and inclined at a predetermined angle on the exit side, the tube axis can be adjusted. For example, it is possible to form a spiral fin that is inclined from the base of the spiral fin, so that the spiral fin of a metal tube with a spiral fin used as a crusher screen etc. can be adjusted to a desired fin height, fin pitch, and fin inclination angle. It has an excellent effect that it can be formed in one step.

[Brief explanation of drawings]

FIG. 1 is a schematic front view showing an implementation state of the method of the present invention, FIG. 2 is an enlarged sectional view taken along the - line in FIG. 1, and FIG. 3 is a schematic front view showing another implementation state of the present invention. 4 is an enlarged vertical sectional view taken along the - line in FIG. 3, FIG. 5 is an enlarged perspective view of the guide shoe, and FIG.
The figure is a schematic front view showing still another implementation state of the present invention, FIG. 7 is an enlarged vertical sectional view taken along the line - in FIG. 6, and FIGS. 11 and 12 are explanatory diagrams showing how to set the inclination angle of the spiral fin in the related art. 1, 2, 3... Rolling roll, 4... Annular groove, 5
...Spiral fin, 6...Plug, 7...Annular groove, 8a, 8b...Guide shaft, 9...Groove, B
...Solid metal rod, P ₀ ...Metal pipe, P ...Metal pipe with spiral fin.

Claims (1)

[Claims] 1. Having a plurality of annular grooves in the circumferential direction of the outer peripheral surface 3.
Or, in a method of manufacturing a metal tube with spiral fins by hot perforating or expanding the diameter of a solid metal rod or metal tube using an inclined rolling mill having four rolling rolls and a piercing plug, A rolling roll in which the angle in the depth direction of the annular groove of each of the rolling rolls with respect to the pass line of the metal rod or metal tube is substantially perpendicular toward the entrance side of the solid metal rod or metal tube, and inclined at a predetermined angle toward the exit side of the solid metal rod or metal tube. A metal tube with a spiral fin, characterized in that the spiral fin is formed in a state perpendicular to the tube axis on the inlet side using a spiral fin, and then the spiral fin is inclined from its root with respect to the tube axis on the outlet side. manufacturing method. 2. Solids are rolled using an inclined rolling mill equipped with a pair of rolling rolls having a plurality of annular grooves in the circumferential direction of the outer peripheral surface, a pair of non-rotating guide shoes having grooves on the side opposite to the pass line, and a piercing plug. A method for manufacturing a metal tube with a spiral fin by hot piercing or diameter expansion rolling of a metal rod or metal tube, the annular groove of the rolling roll and the non-rotating guide shaft relative to the pass line of the solid metal rod or metal tube. The angle in the depth direction of each groove is adjusted to be approximately vertical on the entrance side of the solid metal rod or metal tube, and tilted at a predetermined angle on the exit side using a rolling roll and a non-rotating guide shoe. A method for manufacturing a metal tube with a spiral fin, which comprises forming the spiral fin in a state where it stands upright with respect to the tube axis, and then tilting the spiral fin toward the outlet side from its root with respect to the tube axis.