JP7694964B2 - Pipe processing device and pipe processing method - Google Patents

Description

The present invention relates to a pipe processing device for processing pipe ends, and a pipe processing method using the pipe processing device.

Conventional methods for connecting pipes in a straight line include welding the ends of the pipes together, forming flanges on the ends of the pipes and connecting the overlapping flanges with bolts. In addition, when the pipes are cylindrical, threads are formed on the ends of the pipes and the pipes are connected with joint members having threaded grooves, the pipes are fitted into both ends of a cylindrical joint member with an inside diameter roughly equal to the outside diameter of the pipes, and the pipes are fitted onto both ends of a joint member whose outside diameter in the center is equal to or greater than the inside diameter of the pipe and whose outside diameter gradually decreases toward both ends.

However, all of these methods have the problem that they require a lot of work to connect. In addition, when using joint members, the number of parts increases, which increases costs.

In view of the above, the present invention aims to provide a pipe processing device that processes the ends of pipes in order to easily connect pipes in a straight line while keeping costs down, and a pipe processing method that uses the pipe processing device.

In order to solve the above problems, the pipe processing device according to the present invention comprises:
"A pipe processing device equipped with a forming die into which the ends of a cylindrical pipe are relatively pressed,
The mold is
a cylindrical mold body having a bottom, the mold body having a single-diameter cylindrical portion with a constant inner diameter and a guide portion whose inner diameter gradually increases from the single-diameter cylindrical portion;
a cylindrical member extending from the bottom of the mold body to the open end side in the same axial direction as the mold body;
The cylindrical member is
a large diameter portion located outward from an open end of the mold body and having an outer diameter smaller than an inner diameter of the single diameter cylindrical portion;
and a small diameter shaft portion having an outer diameter smaller than that of the large diameter portion and supporting the large diameter portion against the bottom of the mold body.

The pipe processing device of this configuration is a device for forming a diameter-reduced portion at the end of a cylindrical pipe. By using the pipe processing device of this configuration, a diameter-reduced portion can be formed at the end of a cylindrical pipe by the following pipe processing method. That is,
"The end of a cylindrical pipe, the outer diameter of which is greater than the minimum diameter of the guide portion and less than the maximum diameter of the guide portion, is pressed relatively into the inside of the mold while being in contact with the guide portion, and the end of the cylindrical pipe is pressed from the outer peripheral surface side,
The end of the cylindrical pipe is relatively pulled out from the mold, and the end of the cylindrical pipe is pressed from the inner circumferential surface side by the large diameter portion,
This is a pipe processing method in which a reduced diameter portion is formed at the end of the cylindrical pipe, the reduced diameter portion having an outer diameter approximately equal to the inner diameter of the single diameter cylindrical portion and an inner diameter approximately equal to the outer diameter of the large diameter portion.

As will be described in detail later, simply pressing the end of a cylindrical pipe into the inside of a mold having an inner diameter smaller than the outer diameter of the cylindrical pipe does not allow the formation of a diameter-reduced portion with uniform outer and inner diameters, resulting in non-uniform deformation. In contrast, the mold of the pipe processing device of the present invention is equipped with a columnar member having a large diameter portion inside a bottomed cylindrical mold body. When the end of the cylindrical pipe pressed into the inside of the mold is pulled out relatively from the molded body, the large diameter portion presses the pipe end from the inner peripheral surface side, thereby correcting the non-uniform deformation of the pipe end and forming a diameter-reduced portion with uniform outer and inner diameters.

Cylindrical pipes with diameter-reduced sections at their ends can be connected simply by inserting the diameter-reduced section into the non-machined section of a cylindrical pipe of the same diameter, making the connection easy. In addition, no joint material is required for connection, which helps keep costs down.

In addition to the above configuration, the pipe processing apparatus according to the present invention further comprises:
The cylindrical member may have a base portion at an end opposite to the large diameter portion, the base portion having an outer diameter substantially equal to the inner diameter of the single diameter cylindrical portion, and is detachable from the mold body, and includes a plurality of cylindrical members having base portions with different lengths in the axial direction . Alternatively, the cylindrical member may have a base portion at an end opposite to the large diameter portion, the base portion having an outer diameter substantially equal to the inner diameter of the single diameter cylindrical portion, and is detachable from the mold body, and the base portion is detachable from the small diameter shaft portion.

In this configuration, the cylindrical member is detachable from the mold body, so it can be replaced if it becomes damaged, such as worn out. Furthermore, in this configuration, the cylindrical member has a base. When the end of the cylindrical pipe is pressed into the mold, the innermost end surface inside the mold is easily damaged by the strong pressure from the tip of the pipe. In contrast, in this configuration, the cylindrical member has a base where the inner diameter and outer diameter of the single-diameter tube portion are approximately equal, so the surface on the open end side of the base forms the innermost end surface, and the innermost end surface, which is easily damaged, can be easily replaced by replacing the cylindrical member.

In addition, because the cylindrical member with the base is removable, if multiple cylindrical members with different base heights (axial lengths) are provided, there is an advantage that reduced diameter processed sections with different axial lengths can be formed even when using the same mold body.

In addition to the above configuration, the pipe processing apparatus according to the present invention further comprises:
The guide portion may have an arc-shaped rounded portion at the boundary with the single-diameter cylindrical portion.

In this configuration, because the guide portion has a radius at the boundary with the single-diameter cylindrical portion, the end of the cylindrical pipe, which is deformed so as to bend inward along the inclination of the guide portion, can easily pass over the guide portion and enter the space between the inner peripheral surface of the single-diameter cylindrical portion and the outer peripheral surface of the small-diameter shaft portion. This allows the end of the cylindrical pipe to be pressed fully into the inner space of the mold.

As described above, the present invention provides a pipe processing device that processes the ends of pipes to easily connect pipes in a straight line at low cost, and a pipe processing method that uses the pipe processing device.

FIG. 1 is a cross-sectional view showing the configuration of a forming die provided in a pipe processing apparatus according to one embodiment of the present invention. Figures 2(a), 2(b-1), 2(c-1), and 2(d) are explanatory diagrams of the step of positioning a pipe in the pipe processing method, where Figure 2(b-2) is a cross-sectional view taken along line X-X, and Figure 2(c-2) is a cross-sectional view taken along line Y-Y. 3(a) to 3(c) are explanatory diagrams of the process of relatively press-fitting the end of the cylindrical pipe into the molding die. 4(a) to 4(c) are explanatory diagrams of the process of relatively pulling out the ends of the cylindrical pipe from the molding die. FIG. 5 is an explanatory diagram of processing the end of a cylindrical pipe. 6(a) and 6(b) are explanatory diagrams of the connection between a diameter-reduced processed portion and a non-processed portion of a cylindrical pipe.

Below, we will explain the pipe processing device Ap, which is one embodiment of the present invention, and the pipe processing method using this pipe processing device Ap, using the drawings.

As shown in FIG. 5, the pipe processing device Ap is a processing device that processes a cylindrical pipe 90 consisting of only a non-processed portion 90a with a single (constant) outer diameter by forming a diameter-reduced processed portion 91b whose outer diameter is smaller than that of the non-processed portion 90a at the end of the cylindrical pipe 90, thereby forming a cylindrical pipe 91 having a diameter-reduced processed portion 91b at the end.

As shown in Figures 6(a) and 6(b), by inserting the diameter-reduced processed portion 91b of the cylindrical pipe 91 into the cylindrical pipe 90 or the non-processed portion 90a of the cylindrical pipe 91, cylindrical pipes of the same diameter can be connected in a straight line very easily without the need for a separate joint member.

The pipe processing device Ap includes a forming die 1, a die support 51 that supports the forming die 1, a holding device 60 that holds the cylindrical pipe 90 to be processed, a positioning device 70 that positions the cylindrical pipe 90 to be processed, and a moving device that moves the die support 51 closer to or farther away from the holding device 60.

As shown in FIG. 1, the molding die 1 comprises a die body 10, a cylindrical member 20, and a die base 19. The die body 10 has an overall shape of a bottomed cylinder, a single-diameter cylinder section 11 with a single (constant) inner diameter, and a guide section 12 whose inner diameter gradually increases from the single-diameter cylinder section 11 toward the open end E of the bottomed cylinder. The diameter of the guide section 12 is set according to the size of the cylinder 90 to be machined. In other words, the diameter of the guide section 12 is set so that the outer diameter of the cylindrical pipe 90 to be machined (the outer diameter of the non-machined section 90a) is larger than the minimum diameter of the guide section 12 and is equal to or smaller than the maximum diameter of the guide section 12.

Furthermore, the guide portion 12 has an arc-shaped rounded portion 13 at the boundary with the single-diameter cylindrical portion 11. More specifically, in this embodiment, the guide portion 12 excluding the rounded portion 13 forms an angle of 45 degrees with respect to the plane extended from the open end E.

The cylindrical member 20 extends from the bottom 15 of the mold body 10 toward the open end E in the same axial direction as the mold body 10, and is composed of three parts with different outer diameters: a base part 23, a small diameter shaft part 21, and a large diameter part 22. The base part 23 has an outer diameter approximately equal to the inner diameter of the single diameter cylindrical part 11, and is fixed in abutting contact with the bottom 15 of the mold body 10 inside the mold body 10. The large diameter part 22 has an outer diameter smaller than the inner diameter of the single diameter cylindrical part 11. The difference between the inner diameter of the single diameter cylindrical part 11 and the outer diameter of the large diameter part 22 is set to approximately twice the thickness of the cylindrical pipe 90. The small diameter shaft part 21 has an outer diameter smaller than the outer diameter of the large diameter part 22, and the large diameter part 22 is fixed to the base part 23 so that the large diameter part 22 is located outward from the open end E. That is, the small diameter shaft portion 21 supports the large diameter portion 22 against the bottom 15 of the mold body 10 via the base portion 23. The base portion 23, the small diameter shaft portion 21, and the large diameter portion 22 are all cylindrical with the same axial direction, but the small diameter shaft portion 21 is an elongated cylindrical shape whose axial length is longer than its outer diameter, and the base portion 23 and the large diameter portion 22 are each flat cylindrical whose axial length is shorter than its outer diameter.

In this embodiment, the cylindrical member 20 is detachable from the mold body 10.

The space between the inner peripheral surface of the die body 10 and the outer peripheral surface of the small diameter shaft portion 21 is used for machining the end of the cylindrical pipe, and the space between the inner peripheral surface of the single diameter cylindrical portion 11 and the outer peripheral surface of the small diameter shaft portion 21 is referred to here as the "cylindrical portion inner space S." Since the outer diameter of the base portion 23 is approximately equal to the inner diameter of the single diameter cylindrical portion 11, the surface of the base portion 23 on the open end E side forms the inner end surface 25 of the cylindrical portion inner space S.

The mold base 19 protrudes from the bottom 15 of the mold body 10 on the side opposite the cylindrical member 20. The mold 1 is fixed to the mold support 51 by this mold base 19. The mold support 51 is block-shaped, and the mold 1 is supported by the mold support 51 so that the axial directions of the mold body 10 and the cylindrical member 20 are horizontal. In this embodiment, the mold body 10 is detachable from the mold support 51 via the mold base 19.

The holding device 60 includes a lower holder 61 fixed to a stand (not shown), an upper holder 62 that holds the cylindrical pipe 90 together with the lower holder 61, and a holder lifting device (not shown) that raises and lowers the upper holder 62 relative to the lower holder 61. The lower holder 61 is a block-shaped member having a recess 61r whose cross-sectional shape is a semicircular arc, and the diameter of this semicircular arc is approximately the same as the outer diameter of the cylindrical pipe 90. The opening of the recess 61r of the lower holder 61 faces upward. The upper holder 62 has a shape obtained by turning the lower holder 61 upside down, and the opening of the recess 62r, which has the same shape as the recess 61r, faces downward (see FIG. 2(b-2)). The cylindrical pipe 90 is held with its axial direction horizontal by the lower holder 61 and upper holder 62.

The holder lifting device can be a cylinder device that uses air or oil to move a piston rod back and forth, and that raises and lowers the upper holder 62 by moving the piston rod back and forth.

The positioning device 70 includes a stopper 71 that is a vertical plane, a stopper support 72 that supports the stopper 71, and a stopper lifting device (not shown) that raises and lowers the stopper support 72. The stopper lifting device can be a cylinder device that uses air or oil to advance and retract a piston rod, and raises and lowers the stopper support 72 by the advance and retraction of the piston rod.

The moving device (not shown) may be a device that moves the mold support closer and farther from the holding device that holds the cylindrical pipe, or a device that moves the holding device that holds the cylindrical pipe closer and farther from the mold support. In this embodiment, the lower holder 61 of the holding device 60 is fixed to the stand as described above, while the mold support 51 is moved closer and farther from the holding device 60. Also, as described above, the holding device 60 holds the cylindrical pipe 90 so that its axial direction is horizontal, so the moving device reciprocates the mold support 51 in the horizontal direction. As the moving device, a cylinder device that uses air or oil to move a piston rod back and forth and reciprocates the mold support 51 by the piston rod moving back and forth can be used. Hereinafter, the movement of the molding die 1 in the direction approaching the holding device 60 may be referred to as "forward", and the movement in the direction away from the holding device 60 may be referred to as "rearward".

Next, a pipe processing method using the pipe processing device Ap having the above configuration will be described. First, as shown in FIG. 2(a), the mold 1 is separated from the holding device 60, and the upper holder 62 is raised in the holding device 60 that does not hold the cylindrical pipe 90. The mold 1 and the lower holder 61 are arranged so that the axial directions of the bottomed cylindrical mold body 10 and the columnar member 20 in the mold 1 and the upper end of the recess 61r of the semicircular cross section of the lower holder 61 (the central axis of the cylindrical pipe 90 placed in the recess 61r) are on the same line (on the imaginary line L in the figure). In addition, the positioning device 70 is arranged in a position where the stopper 71 is raised and lowered via the stopper support 72 between the mold 1 separated from the holding device 60 and the holding device 60. The stopper lifting device of the positioning device 70 is driven to lower the stopper support 72 so that the stopper 71 is located on the above line L.

In this state, as shown in Figures 2(b-1) and 2(b-2), the cylindrical pipe 90 is inserted horizontally from the side opposite the side where the stopper 71 is located relative to the holding device 60, and with its tip abutting the stopper 71, the cylindrical pipe 90 is placed in the recess 61r of the lower holder 61.

Next, as shown in Figures 2(c-1) and 2(c-2), the upper holder 62 is lowered so that the opening edge of the recess 61r of the lower holder 61 is butted against the opening edge of the recess 62r of the upper holder 62. This clamps the cylindrical pipe from above and below and holds it firmly.

Then, as shown in FIG. 2(d), the stopper lifting device of the positioning device 70 is driven to raise the stopper 71 via the stopper support 72. As a result, the tip side of the cylindrical pipe 90 held by the holding device 60 is exposed toward the mold 1 by a predetermined length. The position of the stopper 71 relative to the holding device 60 is set so that the length of the portion of the cylindrical pipe exposed from the holding device 60 toward the mold 1 is slightly longer than the axial length of the reduced diameter processed portion 91b to be formed (for example, 1.2 to 1.6 times the axial length of the reduced diameter processed portion 91b).

Next, the moving device is driven to move the mold 1 forward via the mold support 51, and the end of the cylindrical pipe 90 is pressed relatively into the mold 1. This operation is performed in one go, but the process will be explained in order here using Figures 3(a) to 3(c). Below, the end of the cylindrical pipe 90 may be simply referred to as the "pipe end".

When the tip of the cylindrical pipe 90 comes into contact with the mold 1 as the mold 1 advances, the contact position is on the surface of the guide portion 12, as shown in FIG. 3(a). As described above, the outer diameter of the non-machined portion 90a of the cylindrical pipe 90 is larger than the minimum diameter of the guide portion 12 and is equal to or smaller than the maximum diameter of the guide portion 12.

When the mold 1 advances further from this state, as shown in FIG. 3(b), the pipe end is guided by the inclination of the guide portion 12 and bends inward while being pressed into the inside of the mold 1. Because an arc-shaped radius portion 13 is formed at the boundary between the guide portion 12 and the single-diameter cylindrical portion 11, the pipe end easily passes over the radius portion 13 and enters the cylindrical inner space S, which is the space between the inner peripheral surface of the single-diameter cylindrical portion 11 and the outer peripheral surface of the small diameter shaft portion 21. When the pipe end is pressed into the mold 1 in this way, the pipe end is pressed from the outer peripheral surface side and deformed.

The deformation of the pipe end caused by this press-fitting is along the inclination of the guide section 12, but in the space inside the tube S, it does not necessarily deform exactly along the inner circumferential surface of the single-diameter tube section 11. Immediately after the pipe end passes through the guide section 12, the inertial force acts in the direction of the inclination of the guide section 12, making it easy for it to separate from the inner circumferential surface of the single-diameter tube section 11, and if it continues to move forward, it will come into contact with the outer circumferential surface of the small diameter shaft section 21 and will be pushed back by a force. Therefore, in the space inside the tube S, the pipe end deforms unevenly, with a slight undulation. Note that the drawings show the uneven deformation in the space inside the tube S in an exaggerated schematic manner.

The distance that the mold 1 moves when the moving device is driven is set so that, when the mold 1 is closest to the holding device 60, the pipe end reaches the rear end surface 25 of the cylindrical space S, as shown in FIG. 3(c). Specifically, the distance that the mold 1 advances from the position where the tip of the cylindrical pipe 90 abuts against the mold 1 is set to be slightly shorter than the distance between the extension surface of the open end E of the mold 1 and the rear end surface 25.

As shown in FIG. 3(c), when the pipe end has been pressed into the mold 1, for the reasons described above, the deformed pipe end follows the inclination of the guide portion 12, but does not necessarily follow the inner circumferential surface of the single-diameter cylindrical portion 11 at the tip end, and has an unevenly deformed portion.

In the pipe processing device Ap of this embodiment, the uneven deformation is corrected when the forming die 1 retreats, i.e., when it moves away from the holding device 60. When the forming die 1 is retreated via the die support 51 by driving the moving device, the pipe end is relatively pulled out from the forming die 1. This operation is performed in one go, and the process will be explained here in order using Figures 4(a) to 4(c).

As shown in FIG. 4(a), when the pipe end is pulled out slightly from the mold 1, the large diameter portion 22, which was previously located inside the non-machined portion 90a and not in contact with anything, comes into contact with the inner peripheral surface of the non-uniformly deformed pipe end.

As the forming die 1 retreats, the large diameter portion 22 moves toward the tip of the pipe while pressing the unevenly deformed pipe end from the inner peripheral surface side. The pressing force also acts on the portion of the pipe end near the portion pressed by the large diameter portion 22 as if it were dragged, but since the single diameter cylindrical portion 11 exists outside that portion, it is pressed while being sandwiched between the outer peripheral surface of the large diameter portion 22 and the inner peripheral surface of the single diameter cylindrical portion 11. As a result, as shown in FIG. 4(b), after the large diameter portion 22 has passed as the forming die 1 retreats, a reduced diameter processed portion 91b is formed whose outer diameter is approximately equal to the inner diameter of the single diameter cylindrical portion 11 and whose inner diameter is approximately equal to the outer diameter of the large diameter portion 22.

As shown in FIG. 4(c), when the pipe end is completely pulled out of the mold 1, the uneven deformation of the pipe end is corrected, and a cylindrical pipe 91 having a uniformly reduced diameter portion 91b at the end is obtained.

It should be noted that if the outer diameter of the diameter-reduced processed portion 91b is equal to or smaller than the inner diameter of the non-processed portion 90a, the two can be connected, but it is preferable to make the outer diameter of the diameter-reduced processed portion 91b approximately equal to the inner diameter of the non-processed portion 90a, as this allows the two to be connected without rattling and also makes it difficult for dirt or water to get into the connection from the outside.

As described above, the pipe processing device Ap of this embodiment can form a reduced diameter processed portion 91b with a small outer diameter at the end of the cylindrical pipe 90. The cylindrical pipe 91 having the reduced diameter processed portion 91b can be connected by simply inserting the reduced diameter processed portion 91b into the non-processed portion 90a of the cylindrical pipes 90 and 91 of the same diameter, making the connection easy. In addition, no joint member is required for connection, which can reduce costs.

In addition, since the cylindrical member 20 is detachable from the mold body 10, it can be replaced if it becomes damaged, such as worn. Furthermore, in this embodiment, the cylindrical member 20 has a base portion 23. When the pipe end is pressed into the molding die 1, the inner end surface 25 of the cylindrical space S is strongly pressed by the tip of the cylindrical pipe 90 and is easily damaged. In this embodiment, however, the surface on the open end E side of the base portion 23 constitutes the inner end surface 25. Therefore, by replacing the cylindrical member 20, the inner end surface 25, which is easily damaged, can be easily replaced.

In addition, if multiple cylindrical members 20 with different heights (axial lengths) of the base portions 23 are provided, it is possible to form reduced diameter processed portions 91b with different axial lengths even when using the same mold body 10. If the cylindrical members 20 are detachable from the mold body 10 and the base portions 23 are detachable from the small diameter shaft portion 21, it is possible to form reduced diameter processed portions 91b with different axial lengths using the same mold body 10, as described above, by providing base portions 23 with different heights.

In addition, in this embodiment, the mold body 10 is also detachable from the mold support 51 via the mold base 19, so if the mold body 10 becomes damaged, such as worn, it can be easily replaced.

The present invention has been described above with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention, as described below.

For example, in the above example, the mold support 51 supporting the mold 1 moves toward and away from the holding device 60. However, the mold support 51 may be configured to be immobile, and the holding device 60 holding the cylindrical pipe 90 may move toward and away from the mold 1.

In addition, in the above example, the axial direction of the cylindrical pipe 90 to be processed is horizontal when processing the end portion, but similar processing is possible even if the axial direction of the cylindrical pipe 90 is vertical. In this case, the direction of movement of the mold 1 to move closer and farther away from the cylindrical pipe 90 held by the holding device 60 is also vertical.

In addition, in the above, the cylindrical member 20 is illustrated as having a base portion 23, but the cylindrical member may be composed only of a small diameter shaft portion 21 and a large diameter portion 22 without having a base portion 23. In this case, the surface on the open end E side of the bottom portion 15 of the mold body 10 constitutes the inner end surface of the space S inside the cylindrical portion.

Reference Signs List 1: Mold 10: Mold body 11: Single-diameter cylindrical portion 12: Guide portion 13: R-shaped portion 15: Bottom portion 20: Cylindrical member 21: Small-diameter shaft portion 22: Large-diameter portion 23: Base portion Ap: Pipe processing device E: Open end S: Space inside cylindrical portion

Claims (4)

A pipe processing device having a forming die into which an end of a cylindrical pipe is relatively pressed,
The mold is
a cylindrical mold body having a bottom, the mold body having a single-diameter cylindrical portion with a constant inner diameter and a guide portion whose inner diameter gradually increases from the single-diameter cylindrical portion;
a cylindrical member extending from the bottom of the mold body to the open end side in the same axial direction as the mold body;
The cylindrical member is
a large diameter portion located outward from an open end of the mold body and having an outer diameter smaller than an inner diameter of the single diameter cylindrical portion;
a small diameter shaft portion having an outer diameter smaller than that of the large diameter portion and supporting the large diameter portion against a bottom portion of the mold body ,
a base portion having an outer diameter substantially equal to an inner diameter of the single-diameter cylindrical portion at an end opposite to the large-diameter portion, the base portion being detachable from the die body;
The cylindrical member includes a plurality of base portions each having a different axial length.
A pipe processing device characterized by: A pipe processing device having a forming die into which an end of a cylindrical pipe is relatively pressed,
The mold is
a cylindrical mold body having a bottom, the mold body having a single-diameter cylindrical portion with a constant inner diameter and a guide portion whose inner diameter gradually increases from the single-diameter cylindrical portion;
a cylindrical member extending from the bottom of the mold body to the open end side in the same axial direction as the mold body;
The cylindrical member is
a large diameter portion located outward from an open end of the mold body and having an outer diameter smaller than an inner diameter of the single diameter cylindrical portion;
a small diameter shaft portion having an outer diameter smaller than that of the large diameter portion and supporting the large diameter portion against a bottom portion of the mold body,
a base portion having an outer diameter substantially equal to an inner diameter of the single-diameter cylindrical portion at an end opposite to the large-diameter portion, the base portion being detachable from the die body;
The base portion is detachably attached to the small diameter shaft portion.
A pipe processing device characterized by: 3. The pipe processing device according to claim 1, wherein the guide portion has an arc-shaped rounded portion at a boundary with the single-diameter cylindrical portion. A pipe processing method using the pipe processing apparatus according to claim 1 or 2 ,
The end of a cylindrical pipe, the outer diameter of which is greater than the minimum diameter of the guide portion and equal to or less than the maximum diameter of the guide portion, is relatively pressed into the inside of the mold while being in contact with the guide portion, thereby pressing the end of the cylindrical pipe from the outer peripheral surface side,
The end of the cylindrical pipe is relatively pulled out from the mold, and the end of the cylindrical pipe is pressed from the inner circumferential surface side by the large diameter portion,
A pipe processing method comprising forming a reduced diameter portion at an end of the cylindrical pipe, the reduced diameter portion having an outer diameter approximately equal to the inner diameter of the single diameter cylindrical portion and an inner diameter approximately equal to the outer diameter of the large diameter portion.

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