JP2018165548A - Manufacturing method of branch manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and efficiently form a joint hole for connecting a branch joint, and to easily manufacture a branch manifold.SOLUTION: A manufacturing method of a branch manifold has: a pilot hole forming process S1 for forming a pilot hole which penetrates a wall thickness direction toward an internal peripheral face from an external peripheral face of a pipe body in the cylindrical pipe body; a chamfer part forming process S2 for forming a chamfer part by applying chamfering to a periphery of the pilot hole at the external peripheral face side of the pipe body; a burring process S3 for expanding a diameter of the pilot hole by performing cold burring thereto by inserting a punch into the pilot hole in which the chamfer part is formed, and forming a cylindrical part which protrudes to the inside of a radial direction from the internal peripheral face of the pipe body; and a seal face forming process S4 for forming a seal face in the pilot hole which is applied with the burring.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a branch manifold manufacturing method and a branch manifold.

  In a cooling device or the like for cooling various devices, a branch manifold for branching a fluid into a plurality of pipes is used. In this branch manifold, a plurality of connection joints are connected to a header pipe extending in one direction. By connecting the end of the pipe to each connection joint, the fluid is branched from the header pipe into a plurality of pipes.

  Such a branch manifold has been manufactured by welding a plurality of cylindrical connection joints to a header pipe formed with a plurality of branch holes along its longitudinal direction. Each connection joint is formed with a female thread portion for screwing and connecting the branch pipe. However, since there is a possibility that the female screw part may be deformed by heat during welding, the connection joint needs to separate the base end part connected to the header pipe from the distal end part where the female screw part is formed. There is. As a result, the connecting joint becomes long, leading to an increase in the size and weight of the branch manifold. In addition, since it is necessary to move the welding torch around the base end of the connection joint during welding, the interval (pitch) of the connection joint cannot be reduced. This also increases the size and weight of the branch manifold. It leads to.

  On the other hand, for example, Patent Document 1 discloses that a branch hole is formed by performing burring while generating frictional heat in a pipe (header pipe), and the inner and outer sides of the pipe from the inner peripheral surface of the branch hole. The structure which forms the annular wall which each protrudes is disclosed. According to this structure, the joint for connecting piping can be connected to a pipe by forming an internal thread in the internal peripheral surface of an annular wall.

Japanese Patent Application Laid-Open No. 2015-124862

  However, the burring process used in the configuration disclosed in Patent Document 1 is a hot process while generating frictional heat. In the burring process of hot working, the material forming the pipe is melted by frictional heat, and annular walls protrude from the inside and the outside of the pipe, respectively. For this reason, the joint is abutted and fixed to the annular wall protruding outward from the outer peripheral surface of the pipe, and the contact portion between the distal end surface of the joint and the pipe is limited to the distal end surface of the annular wall. Since the annular wall is formed by melting the material forming the pipe by the frictional heat of the hot burring process as described above, the wall thickness is not so large. As a result, it is difficult to increase the support strength of the joint. In order to increase the support strength of the joint, if an attempt is made to increase the wall thickness of the annular wall, the burring process takes time and effort.

  In addition, when the thickness of the pipe is increased, it is difficult to form the branch hole and the annular wall by burring of hot working.

  The present invention has been made in view of the above-described problems, and a branch manifold manufacturing method and a branch manifold capable of easily and efficiently forming a joint hole for connecting a branch joint and easily manufacturing a branch manifold. I will provide a.

  The method for manufacturing a branch manifold according to the first aspect of the present invention is to form a pilot hole in a cylindrical pipe body that forms a through hole penetrating in the thickness direction from the outer peripheral surface of the pipe body toward the inner peripheral surface. A chamfered portion forming step for forming a chamfered portion by chamfering the periphery of the lower hole on the outer peripheral surface side of the tubular body, and inserting a punch into the prepared hole in which the chamfered portion is formed Then, by cold burring, the lower hole is expanded in diameter, and a burring process for forming a cylindrical portion protruding radially inward from the inner peripheral surface of the tubular body, and the burring process And a sealing surface forming step of forming a sealing surface in the prepared hole.

  The branch manifold of the second aspect of the present invention includes a tubular tube, a tubular portion protruding only radially inward from an inner peripheral surface of the tubular body, the tubular body and the tubular portion, A hole formed so as to penetrate in the thickness direction of the tubular body, and is formed around the hole on the outer peripheral surface side of the tubular body, radially inward from the outer peripheral surface, and perpendicular to the central axis of the hole And a planar portion.

  In the branch manifold manufacturing method and the branch manifold according to the present invention, the joint hole for connecting the branch joint can be easily and efficiently formed, and the branch manifold can be easily manufactured.

It is a figure which shows the minimum structure of the manufacturing method of the branch manifold of this invention. It is sectional drawing which shows the pilot hole formation process in the manufacturing method of the branch manifold by this embodiment. It is sectional drawing which shows the burring process in the manufacturing method of the branch manifold by this embodiment. It is sectional drawing which shows the seal surface formation process in the manufacturing method of the branch manifold by this embodiment. It is a figure which shows the minimum structure of the branch manifold of this invention. It is a perspective view of the branch manifold by this embodiment. It is a figure which shows the structure of the branch manifold by this embodiment. It is sectional drawing which looked at the branch manifold by this embodiment in the cross section orthogonal to a central axis. It is sectional drawing which shows the state which connected the piping member to the branch manifold by this embodiment. It is a figure which shows the manufacturing method of the branch manifold by this embodiment. It is sectional drawing which shows the pilot hole formation process in the manufacturing method of the branch manifold by this embodiment. It is sectional drawing which shows the burring process in the manufacturing method of the branch manifold by this embodiment. It is a perspective view which shows the piping which formed the diameter expansion pilot hole at the burring process in the manufacturing method of the branch manifold by this embodiment. It is sectional drawing which shows the plane part formation process in the manufacturing method of the branch manifold by this embodiment. It is a perspective view which shows piping which formed the plane part in the plane part formation process in the manufacturing method of the branch manifold by this embodiment. It is a figure which shows the shape of the punch used with the modification of the manufacturing method of the branch manifold by this embodiment. It is a figure which shows the shape of the tool used at a burring process in the other modification of the manufacturing method of the branch manifold by this embodiment.

  A plurality of embodiments of the present invention will be described below with reference to the drawings. However, with respect to the same parts as those of the conventional example described above with respect to the present embodiment, the same names are used and the detailed description is omitted.

[First Embodiment]
FIG. 1 is a diagram showing a minimum configuration of a branch manifold manufacturing method according to the present embodiment. FIG. 2 is a cross-sectional view showing a pilot hole forming step in the branch manifold manufacturing method according to the present embodiment. FIG. 3 is a cross-sectional view showing a burring process in the branch manifold manufacturing method according to the present embodiment. FIG. 4 is a cross-sectional view showing a sealing surface forming step in the branch manifold manufacturing method according to the present embodiment.
As shown in FIG. 1, the branch manifold manufacturing method may include at least a pilot hole forming step S1, a chamfered portion forming step S2, a burring step S3, and a seal surface forming step S4.

In the lower hole forming step S1, as shown in FIG. 2, the lower hole 2 penetrating in the thickness direction from the outer peripheral surface 1a of the tube 1 toward the inner peripheral surface 1b is formed in the tubular tube body 1. .
In the chamfered portion forming step S <b> 2, the chamfered portion 3 is formed around the lower hole 2 on the outer peripheral surface 1 a side of the tube body 1 to form the chamfered portion 3.

  In the burring process S3, as shown in FIG. 3, a cold burring process is performed by inserting the punch 20 into the prepared hole 2 in which the chamfered portion 3 is formed. Thus, the diameter of the lower hole 2 is increased, and a cylindrical portion 4 that protrudes radially inward from the inner peripheral surface 1 b of the tubular body 1 is formed around the lower hole 2.

  In the seal surface forming step S4, as shown in FIG. 4, the seal surface 5 is formed in the pilot hole 2 that has been burring and expanded in diameter. Thereby, the joint hole 6 to which a piping member (not shown) is connected can be formed in the tubular body 1.

In this manufacturing method of the branch manifold 10A, since the punch 20 is inserted into the prepared hole 2 in which the chamfered portion 3 is formed and cold burring is performed, the frictional force generated between the punch 20 and the chamfered portion 3 is small. That's it. Further, the thickness of the periphery 2a of the lower hole 2 decreases as the chamfered portion 3 is formed so as to approach the lower hole 2 on the inner diameter side. Therefore, when the punch 20 is inserted and cold burring is performed, the periphery 2 a of the lower hole 2 is more easily deformed toward the inner diameter side closer to the lower hole 2. Thus, the cylindrical part 4 can be formed easily. Therefore, even if the thickness of the tubular body 1 is large, the tubular portion 4 can be easily and reliably formed.
Further, by using the cold burring process, there is no protrusion on the outer peripheral side of the tubular body 1 as in the case of using the hot burring process, and the surface of the tubular body 1 is roughened by the heat effect. It can be suppressed from occurring.
In addition, the chamfered portion 3 of the lower hole 2 is deformed by being pressed by the punch 20 when performing cold burring, but after forming the seal surface 5 again after burring, When a piping member (not shown) is attached, the sealing performance between the piping member and the seal surface 5 can be reliably exhibited.
Therefore, the joint hole 6 for connecting a piping member (not shown) can be easily and efficiently formed, and the branch manifold 10A can be easily manufactured.

[Second Embodiment]
FIG. 5 is a diagram showing a minimum configuration of the branch manifold according to the present embodiment. FIG. 6 is a perspective view of the branch manifold according to the present embodiment.
As shown in FIGS. 5 and 6, the branch manifold 10 </ b> C includes a pipe body 11 and a plurality of holes 12 formed in the pipe body 11 and connected to piping members (not shown).

  The tube body 11 has a cylindrical shape extending in one direction. The tubular body 11 is formed with a cylindrical portion 13 that protrudes radially inward from the inner peripheral surface 11 b of the tubular body 11. The tubular portion 13 protrudes only inward in the radial direction from the inner peripheral surface 11b of the tube body 11, and no protruding portion protruding outward in the radial direction is formed on the outer peripheral surface 11a of the tube body 11.

  The hole 12 is formed through the tubular body 11 and the tubular portion 13 in the thickness direction of the tubular body 11.

  Further, on the outer peripheral surface 11 a side of the tube body 11, a flat surface portion 17 orthogonal to the central axis Ch of the hole 12 is formed around each hole 12 on the radially inner side of the outer peripheral surface 11 a.

  Such a branch manifold 10C can be manufactured by forming the cylindrical portion 13 and the hole 12 by cold burring. Therefore, the hole 12 for connecting the piping member (not shown) can be easily and efficiently formed, and the branch manifold 10C can be easily manufactured.

[Third Embodiment]
FIG. 7 is a diagram showing a configuration of the branch manifold according to the present embodiment. FIG. 8 is a cross-sectional view of the branch manifold according to the present embodiment as seen in a cross section orthogonal to the central axis.
As shown in FIGS. 7 and 8, the branch manifold 10 </ b> B includes a pipe body 11 and a plurality of joint holes 16 formed in the pipe body 11 and connected to the piping member 30.

  The tubular body 11 has a cylindrical shape extending in one direction, and is formed of, for example, a stainless alloy. The tubular body 11 is formed with a cylindrical portion 13 that protrudes radially inward from the inner peripheral surface 11 b of the tubular body 11. The tubular portion 13 protrudes only inward in the radial direction from the inner peripheral surface 11b of the tube body 11, and no protruding portion protruding outward in the radial direction is formed on the outer peripheral surface 11a of the tube body 11.

The joint holes 16 are formed at a plurality of locations spaced along the length direction of the tube body 11. Each joint hole 16 is formed through the tubular body 11 and the tubular portion 13 in the thickness direction of the tubular body 11.
The joint hole 16 has an internal thread portion 18 to which the piping member 30 (see FIG. 7) is connected on the inner peripheral surface 11b side of the tube body 11. In addition, the joint hole 16 is formed with a seal surface 15 that expands at a predetermined angle from the female screw portion 18 toward the radially outer side of the tube body 11 on the outer peripheral surface 11a side of the tube body 11.

  Further, on the outer peripheral surface 11 a side of the tubular body 11, a flat portion 17 that is orthogonal to the central axis Ch of the joint hole 16 is formed around each joint hole 16.

FIG. 9 is a cross-sectional view showing a state in which a piping member is connected to the branch manifold according to the present embodiment.
As shown in FIG. 9, the pipe member 30 connected to the joint hole 16 is provided at the end of a cylindrical pipe that forms a fluid flow path. For example, the joint member is made of a stainless alloy or the like. 31 and a seal member 32 are provided.

  The joint member 31 has a substantially cylindrical tubular portion 33 and a shaft-shaped portion 34 having an outer diameter smaller than the outer diameter of the tubular portion 33 and protruding from one end side in the central axis direction of the tubular portion 33. Are integrated. The joint member 31 includes a through hole 35 that penetrates the cylindrical portion 33 and the shaft-shaped portion 34 in the central axis direction. The joint member 31 includes a male screw portion 36 that is screwed into the female screw portion 18 formed in the joint hole 16 of the tube body 11 on the outer peripheral surface of the shaft-like portion 34 on one end side in the central axis direction.

  Further, the joint member 31 has a stepped surface 38 perpendicular to the central axis of the joint member 31 between the cylindrical portion 33 and the shaft-shaped portion 34 having an outer diameter smaller than that of the cylindrical portion 33 on the outer peripheral surface thereof. Have.

Further, the joint member 31 is formed with a seal groove 39 that is continuous in the circumferential direction and recessed inward in the radial direction between the step surface 38 and the shaft-shaped portion 34.
The seal member 32 has an annular shape, and is formed of, for example, a rubber-based material. The seal member 32 is fitted in the seal groove 39.

  Such a piping member 30 is attached to the pipe body 11 by inserting the shaft-like part 34 of the joint member 31 into the joint hole 16 of the pipe body 11 and screwing the male screw part 36 into the female screw part 18. . At this time, the stepped surface 38 of the piping member 30 is in close contact with the flat portion 17 formed around the joint hole 16. Further, the seal member 32 of the piping member 30 is in close contact with the seal surface 15 of the joint hole 16 and is elastically deformed in a direction compressed between the seal surface 15 and the seal groove 39, and the joint hole 16, the joint member 31, and the like. The sealing property between is secured.

Next, a method for manufacturing the branch manifold 10B will be described.
FIG. 10 is a diagram showing a method for manufacturing the branch manifold according to the present embodiment. FIG. 11 is a cross-sectional view showing a pilot hole forming step in the branch manifold manufacturing method according to the present embodiment. FIG. 12 is a cross-sectional view showing a burring process in the branch manifold manufacturing method according to the present embodiment. FIG. 13 is a perspective view showing a pipe in which an enlarged diameter prepared hole is formed in the burring process in the branch manifold manufacturing method according to the present embodiment. FIG. 14 is a cross-sectional view showing a planar portion forming step in the branch manifold manufacturing method according to the present embodiment. FIG. 15 is a perspective view showing a pipe in which a flat portion is formed in the flat portion forming step in the branch manifold manufacturing method according to the present embodiment.
As shown in FIG. 10, the manufacturing method of the branch manifold 10B in the present embodiment includes a pilot hole forming step S11, a chamfered portion forming step S12, a burring step S13, a flat surface portion forming step S14, and a seal surface forming step. S15 and female screw part forming step S16.

  In the lower hole forming step S11, as shown in FIG. 11, the lower hole 12 penetrating in the thickness direction from the outer peripheral surface 11a of the tube body 11 toward the inner peripheral surface 11b is formed in the tubular tube body 11. .

  In the chamfered portion forming step S <b> 12, the chamfered portion 14 is formed around the lower hole 12 on the outer peripheral surface 11 a side of the tube body 11 to form the chamfered portion 14. The chamfered portion 14 is preferably formed in a tapered shape whose inner diameter gradually increases from the inner peripheral surface 11b side to the outer peripheral surface 11a side. The chamfered portion 14 is preferably formed such that the maximum diameter on the outer peripheral surface 11a side of the tube body 11 is substantially equal to the outer diameter of the punch 20 used in the burring step S13.

In the burring process S13, a cold burring process is performed by inserting the punch 20 into the prepared hole 12 in which the chamfered portion 14 is formed.
Here, the punch 20 used for the cold burring process has a curved surface 21 and a diameter-enlarged surface 22 sequentially from a distal end portion 20a positioned in the front of the processing direction toward a base end portion 20b positioned in the rear of the processing direction. Is formed. The curved surface 21 is a convex curved surface that is convex outward from the punch 20. The enlarged diameter surface 22 is formed so that its outer diameter gradually increases from the distal end portion 20a side toward the proximal end portion 20b side. A straight surface 23 having a constant outer diameter is formed on the proximal end portion 20b side with respect to the enlarged diameter surface 22.

  In the burring step S13, the punch 20 is piped along the central axis direction of the lower hole 12 by a pressurizer such as a hydraulic jack or a hydraulic press in a state where the tip 20a is abutted against the chamfered portion 14 of the lower hole 12. The body 11 is pushed in from the radially outer side toward the radially inner side. At this time, a curved surface 21 is formed at the distal end portion 20a of the punch 20, and does not come into surface contact with the chamfered portion 14, but makes line contact with an annular portion continuous in the circumferential direction. Therefore, the frictional force generated between the punch 20 and the chamfered portion 14 can be suppressed. The tubular body 11 is plastically deformed radially inward when the chamfered portion 14 is pressed in the radial direction by the tip 20 a of the punch 20, and the diameter of the tubular body 11 continues to the chamfered portion 14. The inner diameter of the prepared hole 12 continuously formed on the inner side in the direction is enlarged. When the curved surface 21 of the punch 20 passes, the inner diameter of the lower hole 12 is gradually enlarged by the enlarged diameter surface 22. As shown in FIG. 12, the punch 20 stops pushing inward in the radial direction when the diameter-enlarged surface 22 passes through the lower hole 12 and reaches the inner side in the radial direction of the tubular body 11. In this state, the tubular body 11 is formed with a tubular portion 13 that protrudes radially inward from the inner circumferential surface 11 b of the tubular body 11 at the outer circumferential portion of the lower hole 12. The tubular portion 13 protrudes only inward in the radial direction from the inner peripheral surface 11b of the tube body 11, and no protruding portion protruding outward in the radial direction is formed on the outer peripheral surface 11a of the tube body 11. Further, in the center of the cylindrical portion 13, the lower hole 12 is expanded by the punch 20 and a diameter-expanded lower hole (lower hole) 12 'having a constant diameter is formed therethrough.

  After that, if necessary, a pilot hole processing for forming the female screw portion 18 may be performed on the enlarged diameter lower hole 12 ′ with a drill blade having a predetermined outer diameter.

Here, in the cold burring process, the tubular body 11 is pushed inward in the radial direction by the punch 20 to form the enlarged diameter lower hole 12 ′. Thereby, the tubular body 11 is deformed so as to be dragged radially inward around the punch 20. As a result, as shown in FIGS. 12 and 13, the outer peripheral surface 11 a of the tube body 11 is curved around the formed enlarged diameter lower hole 12 ′ and curved inward in the radial direction of the tube body 11. A hollow surface 11k is formed.
Therefore, in the flat surface portion forming step S14, the periphery of the hollow surface 11k of the outer peripheral surface 11a of the tube body 11 is cut by milling or the like. Accordingly, as shown in FIGS. 14 and 15, the center of the enlarged diameter lower hole 12 ′ is located on the outer circumferential surface 11 a side of the tubular body 11, radially inward of the outer circumferential surface 11 a and around the enlarged diameter lower hole 12 ′. A plane portion 17 orthogonal to the axis Ch is formed. The flat portion 17 is formed to be larger than the outer diameter of the step surface 38 of the tubular portion 33 of the piping member 30 shown in FIG.

  In the seal surface forming step S15, as shown in FIG. 8, the seal surface 15 is formed by chamfering a predetermined angle on the outer peripheral surface 11a side of the tubular body 11 with respect to the enlarged diameter lower hole 12 '.

In the female screw portion forming step S16, the female screw portion 18 is formed in a radially inner portion of the tubular body 11 with respect to the seal surface 15 in the enlarged diameter lower hole 12 ′.
Thereby, the joint hole 16 is formed.

In addition, when providing the joint hole 16 in the pipe body 11, first, the said lower hole formation process S11 and the chamfer part formation process S12 are implemented in the predetermined several places along the length direction of the pipe body 11. FIG. Thus, the lower hole 12 and the chamfered portion 14 are formed. Thereafter, the burring step S13 is sequentially performed on each of the pilot holes 12. Further, a planar portion forming step S14, a seal surface forming step S15, and a female screw portion forming step S16 are sequentially performed on each prepared hole 12.
In this way, the tubular body 11 in which a plurality of joint holes 16 are formed is manufactured.

Thereby, the branch manifold 10B provided with the pipe body 11 and the plurality of joint holes 16 formed in the pipe body 11 is completed.
Thereafter, as shown in FIGS. 7 and 9, a plurality of pipes can be connected to the branch manifold 10 </ b> B by connecting the pipe members 30 to the joint holes 16 of the pipe body 11.

According to the manufacturing method of the branch manifold 10B as described above, since the punch 20 is inserted into the prepared hole 12 in which the chamfered portion 14 is formed and cold burring is performed, it occurs between the punch 20 and the chamfered portion 14. Frictional force is small. In addition, the thickness of the periphery 12a of the lower hole 12 decreases as the chamfered portion 14 is formed so as to approach the lower hole 12 on the inner diameter side. Therefore, when the punch 20 is inserted and cold burring is performed, the inner diameter side of the periphery 12a of the pilot hole 12 is easily deformed. In this way, the cylindrical portion 13 can be easily formed. Therefore, even when the thickness of the tubular body 11 is large, the tubular portion 13 can be easily and reliably formed.
Further, by using the cold burring process, there is no protrusion on the outer peripheral surface 11a side of the tube body 11 as in the case of using the hot burring process, and the surface of the tube body 11 is roughened by the heat effect. Etc. can be suppressed.
Further, the chamfered portion 14 of the lower hole 12 is deformed by being pressed by the punch 20 when cold burring is performed, but the seal surface 15 is accurately formed by forming the seal surface 15 again after burring. It can be formed well. Thereby, when the piping member 30 is attached to the cylindrical portion 13, the sealing performance between the piping member 30 and the sealing surface 15 can be reliably exhibited.

In addition, by forming the flat portion 17 around the joint hole 16, when attaching the piping member 30, the stepped surface 38 of the piping member 30 can be brought into surface contact with the flat portion 17 and abutted. Thereby, the attachment strength of the piping member 30 can be increased.
Further, the flat portion 17 is formed on the radially inner side with respect to the outer peripheral surface 11 a of the pipe 11. Therefore, the height at which the piping member 30 protrudes radially outward from the outer peripheral surface 11a of the piping 11 can be suppressed in a state where the piping member 30 is attached to the flat surface portion 17. As a result, it is possible to reduce the size of the cooling device configured by connecting the piping member 30 to the branch manifold 10B.

  In addition, the lower holes 12 are provided at a plurality of positions spaced in the length direction of the tube body 11, and the burring step S13 and the seal surface forming step S15 are sequentially performed on each of the lower holes 12. The pipe body 11 having the joint hole 16 can be efficiently manufactured.

Further, since the female screw portion 18 is formed on the inner peripheral surface of the cylindrical portion 13 protruding radially inward from the inner peripheral surface 11b of the tube body 11, the effective screw length of the female screw portion 18 is ensured, The piping member 30 can be reliably attached.
Moreover, the pipe member 30 can be easily attached by screwing the male screw part 36 of the pipe member 30 into the female screw part 18 of the cylindrical part 13.
According to such a configuration, it is not necessary to provide a connection joint in the branch manifold 10B in order to connect the pipe member 30 provided at the end of the pipe, and naturally, the connection joint to the pipe body 11 is not necessary. There is no need for welding for installation, and there is no need to secure a space for moving the welding torch. Therefore, the pitch between the joint holes 16 and the piping member 30 can be reduced, and the branch manifold 10B can be reduced in size and weight.

  The pipe member 30 can be directly connected to the joint hole 16 of the pipe member 30, but one end of the connection joint is connected to the joint hole 16, and the pipe member is connected to the other end of the connection joint. Is also possible. In this case, a female pipe part for pipe connection to which a pipe member is connected is formed at the other end of the connection joint. In the branch manifold 10B of this embodiment, since it can be manufactured without using welding, the connection joint is not affected by heat due to welding. Therefore, the space | interval of the external thread part formed in the one end part of a connection joint and the internal thread part for piping connection formed in the other end part can be made small, and a shortening of a connection joint can be achieved.

[Modification of Embodiment]
In the present embodiment, the punch 20 is used to widen the lower hole 12 and form the enlarged diameter lower hole 12 ′ in the burring step S13. However, the specific shape is not limited at all, and may be appropriately changed. Can be used.
FIG. 16 is a view showing the shape of a punch used in a modification of the branch manifold manufacturing method according to the present embodiment.
As shown in FIG. 16, the punch 20B used in the burring step S13 includes a curved surface 21 and an enlarged surface from a distal end portion 20a located in the front in the machining direction toward a proximal end portion 20b located in the rear in the machining direction. 22, a maximum diameter portion 24, a reduced diameter portion 25, and a small diameter portion 26 are sequentially formed.

The curved surface 21 is a convex curved surface that is convex outward from the punch 20. The enlarged diameter surface 22 is formed so that its outer diameter gradually increases from the distal end portion 20a side toward the proximal end portion 20b side.
The maximum diameter portion 24 has an outer diameter substantially equal to the inner diameter of the enlarged diameter lower hole 12 ′ to be formed, and has the maximum outer diameter on the distal end portion 20 a side than the small diameter portion 26.
The reduced diameter portion 25 is formed between the maximum diameter portion 24 and the small diameter portion 26, and is formed such that the outer diameter gradually decreases from the front end portion 20a in the processing direction toward the rear end portion 20b.
The small diameter portion 26 is formed on the rear side in the processing direction with respect to the maximum diameter portion 24 and has an outer diameter smaller than the outer diameter of the maximum diameter portion 24.

According to such a configuration, when the punch 20B is pushed into the prepared hole 12 in which the chamfered portion 14 is formed during the cold burring process, the maximum diameter portion 24 of the punch 20B passes through the curved surface 21 and the enlarged diameter surface 22. By passing, the enlarged diameter lower hole 12 ′ and the cylindrical portion 13 having a predetermined inner diameter can be formed.
After the maximum diameter portion 24 of the punch 20B has passed, the reduced diameter portion 25 and the small diameter portion 26 of the punch 20B are positioned inside the enlarged diameter lower hole 12 ′. Thereby, it can suppress that the inner peripheral surface of enlarged diameter lower hole 12 'and punch 20B contact, and can suppress the frictional force between enlarged diameter lower hole 12' and punch 20B. Therefore, the force required for inserting the punch 20B during cold burring is small.

  Further, after the cold burring process is finished, when the punch 20B is pulled out from the enlarged diameter lower hole 12 ′, it passes through the enlarged diameter lower hole 12 ′ with respect to the maximum diameter portion 24 located on the radially inner side of the tube body 11. The reduced diameter portion 25 is located on the front side in the drawing direction of the punch 20B. When viewed in the pulling direction of the punch 20 </ b> B, the reduced diameter portion 25 has an outer diameter that gradually increases from the front to the rear in the drawing direction and continues to the maximum diameter portion 24. Therefore, when the punch 20B is pulled out, it is possible to prevent the maximum diameter portion 24 from being caught in the enlarged diameter lower hole 12 'at the distal end portion of the tubular portion 33 protruding inward in the radial direction of the tube body 11. As a result, it is possible to easily perform the drawing operation of the punch 20B after the cold burring process.

(Still other variations)
In the burring step S13, the following structure can be used to widen the lower hole 12 to form the enlarged diameter lower hole 12 ′.
FIG. 17 is a diagram showing a configuration of a tool used in a burring process in another modification of the branch manifold manufacturing method according to the present embodiment.
As shown in FIG. 17, as a tool for expanding the diameter of the prepared hole 12 formed in the tube body 11, a plurality of spheres 50 whose outer diameters are sequentially increased may be used. The plurality of spheres 50 are set so that their outer diameters increase stepwise. These spherical bodies 50 are pushed into the lower hole 12 by the pushing member 51 from the outer peripheral surface 11a side of the tube body 11 toward the inner peripheral surface 11b side, thereby expanding the diameter of the lower hole 12 and lowering the diameter. Hole 12 'and cylindrical part 13 can be formed.

  In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

DESCRIPTION OF SYMBOLS 1, 11 Tubing body 1a, 11a Outer peripheral surface 1b, 11b Inner peripheral surface 2, 12 Lower hole 2a, 12a Perimeter 4, 13 Cylindrical part 3, 14 Chamfer part 5, 15 Seal surface 6, 16 Joint hole 10A, 10B, 10C Branch manifold 12 hole 12 'Expanded pilot hole (prepared hole)
17 Planar part 18 Female thread part 20, 20B Punch 24 Maximum diameter part 25 Reduced diameter part 26 Small diameter part 30 Piping members S1, S11 Pilot hole forming process S2, S12 Chamfered part forming process S3, S13 Burring process S4, S15 Seal surface Forming step S14 Plane portion forming step S16 Female thread portion forming step S17 Piping member attaching step

Claims (8)

A pilot hole forming step for forming a pilot hole penetrating in a thickness direction from the outer peripheral surface of the tubular body toward the inner peripheral surface thereof in the tubular tubular body;
On the outer peripheral surface side of the tubular body, a chamfered portion forming step of forming a chamfered portion by chamfering the periphery of the prepared hole;
A cylindrical shape that expands the diameter of the lower hole and projects radially inward from the inner peripheral surface of the tubular body by inserting a punch into the lower hole in which the chamfered portion is formed and performing cold burring. A burring process to form a portion;
A seal surface forming step of forming a seal surface in the burring-processed pilot hole;
A method for manufacturing a branch manifold.   The method for manufacturing a branch manifold according to claim 1, further comprising a flat part forming step of forming a flat part perpendicular to a central axis of the lower hole around the lower hole on the outer peripheral surface side of the tubular body.   The method for manufacturing a branch manifold according to claim 1, wherein the cylindrical portion protrudes only radially inward from the inner peripheral surface of the tubular body.   The said lower hole is provided in the several place spaced apart in the length direction of the said tubular body, and the said burring process process and the said seal surface formation process are sequentially performed with respect to each said lower hole. A method for manufacturing the branch manifold according to one item.   The manufacturing method of the branch manifold as described in any one of Claim 1 to 4 which further has the internal thread part formation process which forms an internal thread part in the internal peripheral surface of the said cylindrical part. The punch used in the burring process is:
A maximum diameter portion having an outer diameter substantially equal to the inner diameter of the cylindrical portion;
A small diameter portion having an outer diameter smaller than the outer diameter of the maximum diameter portion on the rear side in the processing direction with respect to the maximum diameter portion,
The manufacturing method of the branch manifold as described in any one of Claim 1 to 5 provided with these.   The branch manifold according to claim 6, wherein the punch has a reduced-diameter portion between which the outer diameter gradually decreases from the front to the rear in the processing direction between the maximum diameter portion and the small diameter portion. Production method. A tubular tube,
A cylindrical portion protruding only radially inward from the inner peripheral surface of the tubular body,
A hole formed through the tubular body and the tubular portion in the thickness direction of the tubular body;
A flat portion that is formed around the hole on the outer peripheral surface side of the tubular body on the radially inner side of the outer peripheral surface and orthogonal to the central axis of the hole;
Branch manifold with

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