JP2015047634A - Method for manufacturing pipe with slit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pipe with a slit capable of achieving a long life of a punch.SOLUTION: A punch (2) includes: an apical surface (21); side surfaces (22 and 23) connected to the apical surface (21); and a shearing inclined plane (24) connected to the apical surface (21) and the side surfaces (22 and 23), being connected to the apical surface (21) in an obtuse angle shape. The punch (2) is relatively moved with respect to a pipe (1) in a first direction toward the depth side inside the pipe (1) from the end side of the pipe (1) so that press-cutting is performed by the shearing inclined plane (24). Then, the punch (2) is relatively moved with respect to the pipe (1) in a second direction different from the first direction from inside toward outside of the pipe (1) so that punching is performed by the shearing inclined plane (24).

Description

  The present invention relates to a method for manufacturing a pipe having a slit at an end.

Patent Document 1 describes a method of machining a slit at an end of a pipe. The outer periphery of the pipe is clamped with a die and moved into the pipe from the open end of the pipe by a punch having a movement locus inclined to the axis of the pipe, thereby forming a slit extending from the end face of the pipe.
Patent Document 2 describes that a slit is formed in a pipe by inserting a punch into the pipe and performing a punching process by moving the punch outward in the radial direction of the pipe.
Other processing methods are described in Patent Documents 3 to 6.

JP-A-8-141665 JP-A-3-1422021 Japanese Patent Publication No. 63-49576 JP 2002-282916 A Japanese Patent Publication No. 7-83903 Japanese Patent No. 3770431

  In the processing method described in Patent Document 1, since the front end side of the punch is acute, the rigidity on the front end side of the punch is low. Therefore, it is desired to improve the punch life. In the processing method described in Patent Document 2, since the punch shears the slit of the pipe at a time, a large load is applied to the punch. Therefore, also in the said processing method, it is necessary to aim at the improvement of the lifetime of a punch.

  This invention is made | formed in view of such a situation, and it aims at providing the manufacturing method of the pipe which has a slit which can aim at the lifetime improvement of a punch.

A method of manufacturing a pipe having a slit at an end according to the present means includes a die having a recess corresponding to the slit, a tip surface, a side surface connected to the tip surface, and the tip surface and the side surface. And a punch having a sloping inclined surface connected in obtuse angle to the tip surface.
The manufacturing method includes a pipe arranging step of arranging the pipe on the die so that an outer peripheral surface of the pipe is supported by the die, and a front end surface of the punch facing the back side of the pipe. A punch disposing step of disposing the punch so that the normal line of the shearing inclined surface of the punch has an angle with respect to the axial direction of the pipe, and the shearing inclined surface faces the recess of the die. And by moving the punch relative to the pipe in a first direction from the end of the pipe toward the inner side of the pipe, the shearing inclined surface causes the rear side of the pipe to move backward. The cutting process for machining a part of the slit and the second direction that is different from the first direction and that extends from the inside to the outside of the pipe. By relatively moving the switch to the pipe, by performing a punching process of the pipe by the shearing inclined surface, and a punching step of processing the remaining of the slit.

  The slit processing is performed by dividing into a punching process performed by relatively moving the punch in the first direction and a punching process performed by relatively moving the punch in the second direction. That is, a part of the slit is processed by the press-cut process, and the remaining slit is processed by the punching process. Therefore, since the punch does not shear the slit at a time, the life of the punch can be extended.

  In particular, the punch is arranged so that the normal line of the inclined slope for shearing of the punch has an angle with respect to the axial direction of the pipe. Therefore, the side edge of the slit is gradually sheared in both the press-cut process and the punching process. Therefore, the bending stress generated in the punch is reduced, and the life of the punch can be extended.

  Further, the tip end face of the punch and the inclined surface for shearing are connected in an obtuse angle. That is, the angle formed by the tip end face of the punch and the inclined slope for shearing is obtuse. Accordingly, the rigidity on the tip end side of the punch is increased. This itself can extend the life of the punch. However, forming the tip end side of the punch in an obtuse shape as described above can be achieved by making the second direction in the punching process different from the first direction in the push-cut process. Here, in the push-cut process, the vicinity of the ridgeline between the shearing inclined surface and the side surface is processed, whereas in the punching process, the vicinity of the ridgeline between the shearing inclined surface and the tip surface is mainly processed. That is, paying attention to the fact that the respective parts to be processed are different, and making the respective processing directions different, the above-mentioned effects can be obtained.

<Embodiment>
A preferred embodiment of the pipe manufacturing method according to this means will be described below.
Preferably, in the punch arranging step, the punch is arranged such that a tip end surface of the punch is orthogonal to the axial direction of the pipe, and the first direction in the push-off step is parallel to the axial direction of the pipe. In the punching step, the second direction is parallel to the front end surface of the punch and is a direction from the center of the pipe to the radially outer side.

  By making the first direction in the push-cutting process parallel to the axial direction of the pipe, the portion of the punch that can enter the pipe in the push-cutting process can be enlarged. That is, the punch thickness can be increased. Therefore, the rigidity of the punch can be increased. In addition, the angle formed between the tip surface of the punch and the inclined inclined surface by making the tip surface of the punch perpendicular to the axial direction of the pipe and making the second direction in the punching process outward in the radial direction of the pipe Can be at a large angle. Therefore, it is possible to increase the rigidity of the punch.

Preferably, the punch is an anti-shear surface connected to the tip surface and the side surface and positioned on the back surface side with respect to the shearing inclined surface, the punch having a contact surface parallel to the axial direction of the pipe. Has an anti-shear surface.
By making the contact surface of the anti-shearing surface a surface parallel to the axial direction of the pipe, the anti-shearing surface can move along the inner peripheral surface of the pipe when performing push-cut processing. As a result, the punch thickness (corresponding to the distance between the shearing inclined surface and the anti-shear surface) can be increased. That is, the rigidity of the punch can be increased.

Preferably, a separation distance between the tip surface side of the shearing inclined surface and the tip surface side of the anti-shear surface is shorter than an inner diameter of the pipe, The separation distance between the base end side and the base end side of the anti-shear surface is longer than the inner diameter of the pipe.
Thereby, since the thickness (equivalent to the distance between the shearing inclined surface and the anti-shearing surface) of the base end side of the punch can be increased, it is possible to increase the rigidity of the punch.

Preferably, the pressing step processes at least half of the side edge of the slit in the depth direction, and the punching step includes the other half or less of the side edge of the slit in the depth direction and the back edge of the slit. Is processed.
By forming more than half of the side edge in the depth direction by pressing, bending stress generated in the punch during punching can be sufficiently reduced. Therefore, the life of the punch can be extended.

It is a perspective view which shows the pipe 1 of this embodiment. It is a perspective view which shows the punch 2 used for the manufacturing method of the pipe 1 of this embodiment. In the manufacturing method of the pipe 1, it is an axial sectional view of the pipe 1 in the initial placement step. It is 3B-3B sectional drawing in FIG. In the manufacturing method of the pipe 1, it is an axial sectional view of the pipe 1 in the middle of the push-off process. In the manufacturing method of the pipe 1, it is an axial sectional view of the pipe 1 at the end of the push-off process. In the manufacturing method of the pipe 1, it is an axial sectional view of the pipe 1 in the punching process.

(1. Structure of the finished pipe 1)
The pipe 1 as a finished product will be described with reference to FIG. The pipe 1 is made of metal, for example. That is, the pipe 1 is formed of a material that can perform a press-cut process and a punch process, which is a kind of shearing process. Here, FIG. 1 shows only the end portion of the pipe 1. The pipe 1 may be a straight pipe or a curved pipe. Moreover, although the pipe 1 shown in FIG. 1 shows an annular shape, a pipe having a non-circular cross section can also be used. The inner diameter at the end of the pipe 1 is Di1.

  A slit 10 is formed at the end of the pipe 1. The slit 10 is formed to extend from the end of the pipe 1 in the direction of the central axis X at the end of the pipe 1 (hereinafter referred to as “the axial direction of the pipe”). The slit 10 has a linear back edge 11 and side edges 12 and 13 on both sides parallel to each other. The depth of the slit 10, that is, the axial length from the end of the pipe 1 to the back edge 11, is De1. The width of the slit 10, that is, the distance between the side edges 12 and 13 on both sides is Wi1.

(2. Manufacturing method of pipe 1)
The manufacturing method of the pipe 1 demonstrated below is a method of processing the slit 10 with respect to the pipe 1 in which the slit 10 is not formed. The manufacturing method of the pipe 1 is a method of performing punching and punching using the punch 2 and the die 3.

(2-1. Structure of punch 2)
The structure of the punch 2 will be described with reference to FIG. The punch 2 includes a base portion 20a and a protruding portion 20b. The base 20a is a part fixed to the driving means in the manufacturing apparatus. The protrusion 20b is formed so as to protrude from the base 20a. This protrusion 20b is a part for processing the slit 10 of the pipe 1.

  The protrusion 20 b of the punch 2 has a tip surface 21, side surfaces 22 and 23 on both sides, a shearing inclined surface 24, and an anti-shearing surface 25. The front end surface 21 is a plane located at the end of the protruding portion 20b in the protruding direction. The side surfaces 22 and 23 are planes connected to the tip end surface 21 and are parallel to each other.

The shearing inclined surface 24 is connected to the tip surface 21 and the side surfaces 22 and 23 on both sides, and is connected to the tip surface 21 in an obtuse angle. The shearing inclined surface 24 may be formed in a tapered flat shape inclined with respect to the distal end surface 21, or may be formed in a curved surface shape in which a contact surface is inclined with respect to the distal end surface 21.
The anti-shearing surface 25 is connected to the front end surface 21 and the side surfaces 22 and 23 on both sides, and is located on the back side with respect to the shearing inclined surface 24. The anti-shear surface 25 is formed in a convex curve shape along the axial direction of the cylindrical inner peripheral surface. Specifically, the contact surface of the anti-shear surface 25 is parallel to the central axis X of the pipe 1 in a state where the tip surface 21 is disposed so as to be orthogonal to the axial direction of the pipe 1.

  Here, the separation distance between the point P1 on the distal end surface 21 side of the shearing inclined surface 24 and the point P2 on the distal end surface 21 side of the anti-shear surface 25 is Ha. Hereinafter, Ha is referred to as the tip side thickness. A separation distance between a point P3 on the base end side (base portion 20a side) of the shearing inclined surface 24 and a point P4 on the base end side (base portion 20a side) of the anti-shear surface 25 is Hb. Hereinafter, Hb is referred to as a proximal side thickness. The distal end side thickness Ha is shorter than the proximal end side thickness Hb. Furthermore, the tip end side thickness Ha is shorter than the inner diameter Di1 of the pipe 1 shown in FIG. Further, the base end side thickness Hb is longer than the inner diameter Di1 of the pipe 1 shown in FIG.

Further, the widths of the side surfaces 22 and 23 on both sides of the protrusion 20b are Wi2. The width Wi2 is equal to the separation distance Wi1 between the side edges 12 and 13 of the slit 10.
Here, the vicinity of the ridge line L1 between the distal end surface 21 and the shearing inclined surface 24 corresponds to a part forming the inner edge 11 of the slit 10, and the ridgeline L2 between the shearing inclined surface 24 and the side surfaces 22 and 23 on both sides, The vicinity of L3 corresponds to a portion where the side edges 12 and 13 of the slit 10 are formed.

(2-2. Structure of Die 3)
Next, the structure of the die 3 will be described with reference to FIGS. The die 3 is formed with a circular through hole 30 a for supporting the outer peripheral surface of the end of the pipe 1. Further, a recess 30 b corresponding to the slit 10 of the pipe 1 is formed on one end side of the circular through hole 30 a of the die 3. That is, the inner edge 31 of the recess 30 b and the side edges 32 and 33 on both sides have shapes corresponding to the inner edge 11 of the slit 10 and the side edges 12 and 13 on both sides.

(2-3. Initial placement step)
An initial placement process (a pipe placement process, a punch placement process) in the manufacturing method of the pipe 1 will be described with reference to FIGS. 3A and 3B. An operator fixes the die 3 to a manufacturing apparatus (not shown). The operator inserts the end of the pipe 1 before processing into the circular through hole 30a of the die 3 and arranges the pipe 1 on the die 3 so that the outer peripheral surface of the pipe 1 is supported by the die 3 ( Pipe placement process). At this time, the position where the slit 10 is processed in the pipe 1 corresponds to the recess 30 b of the die 3.

  Subsequently, the worker fixes the base portion 20a of the punch 2 to a moving body that is moved by the driving device of the manufacturing apparatus. Here, the drive device can move the punch 2 in the axial direction of the circular through hole 30a of the die 3 and also move in the radial direction of the circular through hole 30a and along the recess 30b. Can do. The die 3 may be moved while the punch 2 is fixed.

  Here, the punch 2 is arranged so that the front end surface 21 of the punch 2 faces the back side of the pipe 1 and the front end surface 21 of the punch 2 is orthogonal to the axial direction of the pipe 1 (punch arranging step). ). Therefore, the contact surface of the anti-shear surface 25 of the punch 2 is parallel to the axial direction of the pipe 1. Further, the normal line of the shearing inclined surface of the punch 2 has an angle with respect to the axial direction of the pipe 1.

  Further, the punch 2 is disposed at a position where the entire tip end face 21 of the punch 2 can be inserted into the pipe 1. Here, as described above, the base end side thickness Hb of the punch 2 is larger than the inner diameter Di1 of the pipe 1. Accordingly, a part of the shearing inclined surface 24 faces the end surface of the pipe 1 before processing in the axial direction. At this time, the punch 2 is arranged so that the shearing inclined surface 24 faces the recess 30 b of the die 3.

(2-4. Push-off process)
Following the initial placement step, a push-off step is performed. The push-off process will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, the punch 2 is moved relative to the die 3 in the first direction parallel to the axial direction of the pipe 1. As described above, the front end surface 21 of the punch 2 can be inserted inside the pipe 1. Therefore, the front end surface 21 of the punch 2 enters the pipe 1 without contacting the pipe 1.

  Here, a part of the inclined surface for shearing 24 faces the end surface of the pipe 1 before processing in the axial direction. Therefore, when the punch 2 is relatively moved in the first direction, the shearing inclined surface 24 comes into contact with the end surface of the pipe 1. Furthermore, by continuing relative movement of the punch 2 in the first direction, the shearing inclined surface 24 performs push-cut processing from the end of the pipe 1 toward the back side. That is, shearing (push-cutting) is performed by the ridgelines L2 and L3 (shown in FIG. 2) of the shearing inclined surface 24 and the side edges 32 and 33 of the recess 30b of the die 3. Then, a part of the end portion of the pipe 1 is turned radially outward while being along the shearing inclined surface 24 and enters the recess 30 b of the die 3.

  Then, as shown in FIG. 5, the punch 2 is relatively moved in the first direction until the tip surface 21 of the punch 2 reaches a position that substantially coincides with the rear edge 31 of the recess 30 b of the die 3. In this way, a part of the slit 10, specifically, part of the side edges 12 and 13 of the slit 10 is processed.

  Here, as shown in FIG. 5, when the push-cut processing is completed, a portion from the end of the pipe 1 to the depth De3 is cut off. The cut depth De3 is set to be half or more of the depth De1 (shown in FIG. 1) of the slit 10. This relationship is adjusted according to the depth De1 of the slit 10 and the inclination angle of the shearing inclined surface 24.

(2-5. Punching process)
Subsequent to the push-off process, a punching process is performed. The punching process will be described with reference to FIG. As shown in FIG. 6, the punch 2 is moved relative to the die 3 in the second direction from the inside to the outside of the pipe 1. Here, the second direction is parallel to the tip surface 21 of the punch 2 and is a direction from the center of the pipe 1 to the radially outer side. That is, the second direction in the punching process is a direction different from the first direction in the push-off process, specifically, a direction orthogonal to the first direction.

  Then, first, the pipe 1 is processed so as to be turned outward in the radial direction by the vicinity of the ridgelines L2 and L3 of the inclined inclined surface 24. Then, after the ridgeline L1 of the shearing inclined surface 24 (the ridgeline with the tip surface 21) contacts the pipe 1, the vicinity of the ridgeline L1 of the shearing inclined surface 24 and the back edge 31 of the recess 30b of the die 3 A shearing process (punching process) is performed. In this way, the remainder of the slit 10 is processed. That is, the remaining half or less of the side edges 12 and 13 of the slit 10 in the depth direction and the back edge 11 of the slit 10 are processed by punching.

(3. Summary)
As described above, the processing of the slit 10 is performed by dividing into a punching process performed by relatively moving the punch 2 in the first direction and a punching process performed by relatively moving the punch 2 in the second direction. That is, a part of the slit 10 is processed by the press-cut process, and the remaining slit 10 is processed by the punching process. Therefore, since the punch 2 does not shear the slit 10 at a time, the life of the punch 2 can be extended.

  In particular, the punch 2 is arranged such that the normal line of the shearing inclined surface 24 of the punch 2 has an angle with respect to the axial direction of the pipe 1. Accordingly, the side edges 12 and 13 of the slit 10 are gradually sheared in both the push-cut process and the punching process. Therefore, the bending stress generated in the punch 2 is reduced, and the life of the punch 2 can be extended.

  Furthermore, the front end surface 21 of the punch 2 and the shearing inclined surface 24 are connected in an obtuse angle. That is, the angle formed between the tip end surface 21 of the punch 2 and the shearing inclined surface 24 is obtuse. Accordingly, the rigidity on the tip side of the punch 2 is increased. As a result, the life of the punch 2 can be extended. However, forming the front end side of the punch 2 as an obtuse angle as described above can be achieved by making the second direction in the punching process different from the first direction in the push-cut process. Here, in the push-cut process, the vicinity of the ridgelines L2 and L3 between the shearing inclined surface 24 and the side surfaces 22 and 23 is processed, whereas in the punching process, the ridgeline L1 between the shearing inclined surface 24 and the front end surface 21 is processed. The neighborhood mainly processes. That is, paying attention to the fact that the respective parts to be processed are different, and making the respective processing directions different, the above-mentioned effects can be obtained.

  Further, by making the first direction in the push-off process parallel to the axial direction of the pipe 1, the portion of the punch 2 that can enter the pipe 1 in the push-off process can be increased. That is, the thicknesses Ha and Hb of the punch 2 can be increased. In particular, by making the contact surface of the anti-shear surface 25 parallel to the axial direction of the pipe 1, the anti-shear surface 25 moves along the inner peripheral surface of the pipe 1 when performing push-cut processing. You can As a result, the thicknesses Ha and Hb of the punch 2 can be increased. That is, the rigidity of the punch 2 can be increased.

  Furthermore, by making the front end surface 21 of the punch 2 orthogonal to the axial direction of the pipe 1 and making the second direction in the punching process outward in the radial direction of the pipe 1, The angle formed with the inclined surface 24 can be a large angle. Therefore, the rigidity of the punch 2 can be increased.

  Further, the base end side thickness Hb of the punch 2 is larger than the inner diameter Di1 of the pipe 1. Thereby, the rigidity of the base end side of the punch 2 can be increased. Here, a large moment is generated in the punch 2 in the punching process. By increasing the rigidity of the base end side of the punch 2, the punch 2 can withstand a large moment.

  Here, as described above, in the push-off process, half or more of the side edges 12 and 13 of the slit 10 are processed in the depth direction, and in the punching process, the remaining half or less of the side edges 12 and 13 of the slit 10 in the depth direction are processed. It was decided to process.

  Compared to the case where the slit 10 is processed only by punching (processing that moves the punch 2 in the radial direction) without performing the press-cut process, the bending stress generated in the punch 2 in the punching process can be reduced as described above. It can be made much smaller. Below, the simple calculation method of the bending stress (sigma) at the time of comparing both is demonstrated.

The thickness of the pipe 1 in the second direction of punching is 2 mm, the width Wi1 of the rear edge 11 of the slit 10 is 7 mm, the depth De1 of the side edges 12 and 13 of the slit 10 is 9 mm, and the shear resistance of the pipe 1 is 40 kgf / mm ² , the width Wi 2 of the punch 2 is 7 mm, the base end side thickness Hb of the punch 2 is 13 mm, and the depth De 2 of the shearing inclined surface 24 is 10 mm.

  Here, in the present embodiment, it is assumed that the target surface of the punching process is a right triangular portion among the entire rear edge 11 of the slit 10 and the half of the side edges 12 and 13 in the depth direction. The reason why the right-angled triangular portion is used is that, as shown in FIG. 5, about half of the triangular-shaped portion remains due to the shearing inclined surface 24 in the back side portions of the side edges 12 and 13.

In this case, the load Pa [kgf / mm ² ] generated in the punch 2 is an addition value of the load Pa1 due to the back edge 11 and the load Pa2 due to the side edges 12 and 13, as shown in the equation (1). The moment Ma [kgf · mm] is expressed by equation (2), the section modulus Za is expressed by equation (3), and the bending stress σa [kgf / mm ² ] is expressed by equation (4).

As a comparative example, it is assumed that the slit 10 is processed only by punching. In this case, the thickness of the pipe 1 in the punching process is 2 mm, the width Wi1 of the rear edge 11 of the slit 10 is 7 mm, the depth De1 of the side edges 12 and 13 of the slit 10 is 9 mm, and the shear resistance of the pipe 1 is 40 kgf. / Mm ² , the width Wi 2 of the punch 2 is 7 mm, the thickness Hc of the punch 2 is 9 mm, and the protrusion De of the punch 2 from the moment reference position is 10 mm.

In this case, the load Pb [kgf / mm ² ] generated in the punch 2 is an addition value of the load Pb1 due to the back edge 11 and the load Pb2 due to the side edges 12 and 13, as shown in the equation (5). The moment Mb [kgf · mm] is expressed by equation (6), the section modulus Zb is expressed by equation (7), and the bending stress σb [kgf / mm ² ] is expressed by equation (8).

  From the equations (4) and (8), according to the present embodiment, the bending stress σ generated in the punch 2 is 1/5 or less as compared with the comparative example. As described above, the bending stress generated in the punch 2 in the punching process becomes very small, so that the life of the punch 2 is greatly improved.

  As described above, it is possible to extend the life of the punch 2 by setting the first direction by the push cutting process and the second direction by the punching process to be different directions. Here, in the above embodiment, the punch 2 is relatively moved in the axial direction of the pipe 1 in the push-off process. The punch 2 may be relatively moved in a direction slightly inclined with respect to the axial direction of the pipe 1. In this case, the above effect due to relative movement of the punch 2 in the axial direction of the pipe 1 is not achieved. Further, in the punching process, the punch 2 was relatively moved in the radial direction of the pipe 1. The punch 2 may be relatively moved in a direction slightly inclined with respect to the radial direction of the pipe 1. In this case, the above effect due to relative movement of the punch 2 in the radial direction of the pipe 1 is not achieved.

1: pipe, 10: slit, 11: back edge, 12, 13: side edge, 2: punch, 21: tip surface, 22: side surface, 24: inclined surface for shearing, 25: anti-shearing surface, 3: die, 30a: Circular through hole, 30b: Recess, 31: Back edge, 32: Side edge, Di1: Inner diameter of pipe, Ha: Thickness at the tip end of the punch, Hb: Thickness at the base end side of the punch

Claims (5)

A method of manufacturing a pipe having a slit at an end,
A die having a recess corresponding to the slit;
A punch having a front end surface, a side surface connected to the front end surface, and an inclined surface for shear connected to the front end surface and the side surface and connected to the front end surface in an obtuse angle;
Use
A pipe placement step of placing the pipe on the die such that an outer peripheral surface of the pipe is supported by the die;
The normal surface of the shearing inclined surface of the punch has an angle with respect to the axial direction of the pipe so that the front end surface of the punch faces the back side of the pipe, and the shearing inclined surface is A punch placement step of placing the punch so as to face the recess of the die;
By moving the punch relative to the pipe in a first direction from the end of the pipe toward the inner side of the pipe, the shearing inclined surface moves from the end of the pipe toward the inner side. By performing the press-cut process, a press-cut process of processing a part of the slit,
The pipe is punched by the shearing inclined surface by moving the punch relative to the pipe in a direction different from the first direction and in a second direction from the inside to the outside of the pipe. A punching process for processing the remainder of the slit by performing,
A method for manufacturing a pipe having a slit. In the punch placement step, the punch is placed so that the tip end surface of the punch is orthogonal to the axial direction of the pipe,
The first direction in the push-off step is parallel to the axial direction of the pipe,
The second direction in the punching step is parallel to the tip surface of the punch and is a direction from the center of the pipe to the radially outer side.
The manufacturing method of the pipe which has a slit of Claim 1. The punch is an anti-shearing surface that is connected to the front end surface and the side surface and is located on the back side with respect to the shearing inclined surface, and has a contact surface parallel to the axial direction of the pipe. Having
The manufacturing method of the pipe which has a slit of Claim 2. The separation distance between the tip surface side of the shearing inclined surface and the tip surface side of the anti-shear surface is shorter than the inner diameter of the pipe,
The separation distance between the base end side of the shearing inclined surface and the base end side of the anti-shear surface is longer than the inner diameter of the pipe.
The manufacturing method of the pipe which has a slit of Claim 3. The push-cutting step processes more than half of the side edge of the slit in the depth direction,
In the punching step, the remaining half or less in the depth direction of the side edge of the slit and the back edge of the slit are processed.
The manufacturing method of the pipe which has a slit as described in any one of Claims 1-4.

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