JPH06106268A - Pipe expanding device - Google Patents

Abstract

PURPOSE:To form an expanded pipe having a high roundness using segmental dies by phasing the spaces between segmental dies against the spaces of segmental die of the adjacent column in the peripheral direction. CONSTITUTION:The segmental dies 13a, 13b, 13c and 13d devided in the peripheral direction are arranged at the outer peripheral part of a taper-shaped core metal which is moved back and forth. The arranged segmental dies are also plurally devided in the axial direction of the core metal and arranged to be shown as 13a, 13b...16c, 16d. Mutual space D between the segmental dies devided in lines such as 13a and 13b are phased in the peripheral direction against the space D between the segmental dies of the adjacent column. Thus, the wall thickness of expanded and opened pipe is uniformized over the entire peripheral part and the expanding ratio of pipe is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube expanding device.

[0002]

2. Description of the Related Art Conventionally, as a pipe expanding device for expanding the end of a metal pipe, for example, in the case of correcting the pipe diameter of an inlet pipe of a muffler, as shown in FIGS. Split molds 1, 2, 3, 4 divided in the direction
Is provided in a holder 5 slidably in the radial direction, and a cored bar 6 having a tapered surface having the same inclination as the inclination is formed on the outer circumference in the tapered holes 1a to 4a formed in the center of the split molds 1 to 4. In order to be able to move forward and backward, the pipe before expansion is fitted to the outer periphery of the split molds 1 to 4, and then the core metal 6 is advanced in the direction of arrow A in FIG. There is one in which the expanded portion 7a of the pipe 7 is expanded as shown in FIG.

The gap D formed by the split molds 1 to 4 is formed in series along the generatrix direction over the entire length (for example, JP-A-4-100648).

[0004]

As described above, in the split mold divided in the circumferential direction, the arrow B is provided between the adjacent split molds, for example, between the split molds 1 and 2 in FIG.
As the gap D between the split molds 1 and 2 expands due to the movement in the direction, the horizontal component forces P ₁ and P which are contradictory to each other on the portion 7b of the pipe 7 located in the gap D portion as shown in FIG. ₂
Works.

Therefore, in the case where the gap D is formed over the entire length in the generatrix direction in the expanded portion of the pipe as in the conventional case, the part 7b of the pipe is flat as shown in FIG. As well as being shaped, it is formed over the entire length in the generatrix direction as shown in FIG.

As a result, when the expanded portion of the pipe does not form a perfect circle and is fitted into another perfect circular connecting part, a gap is created by the flat part, and problems such as fluid leakage occur. Further, there is a problem that the portion 7b is stretched thinner than the other portions, the thickness of the pipe becomes uneven, and the pipe expansion ratio is poor.

Further, the axial lengths of the split molds 1 to 4 are shown in FIG.
Since it is long as shown in 0 (a), the core metal 6
The maximum distance L ₁ between the point of action of the load P _{4 received} by the contact point and the point of action of the load P _{5 received} by the contact resistance with the holder
Becomes longer, a large shear stress is generated and the split mold 1 ~
4 also has a problem of being cut off c near its center.

Therefore, the present invention is intended to solve such a problem.

[0009]

In order to achieve the above-mentioned object, the present invention provides a split die which is divided in the circumferential direction on the outer periphery of a taper-shaped core metal which advances and retreats. The mold was divided into multiple rows in the axial direction of the gold, and the gaps between the split molds in each row were circumferentially aligned with the gaps between the split molds in adjacent rows. It is characterized by.

[0010]

The pipe (7) to be expanded is fitted around the outer periphery of each split mold (13a ...). Next, the cored bar (9) is advanced in the direction of arrow A, and the split molds (13a ...) Are pushed and moved in the radial direction by the tapered surface (9a) on the outer periphery thereof.
As a result, the expanded portion (7a) of the fitted paif (7)
Will be expanded.

By this expansion, for example, a part (7b) of the pipe located in the gap (D) formed between the split molds (13a), (13b) in the first row 13 is circumferentially ( It is pulled horizontally.

However, since the split mold (14a) of the adjacent second row (14) is present next to this gap (D), the pipe located in the gap D in the first row (13) is A spreading force P _{3 in the} radial direction (upward) also acts on a part (7b) of the split mold (13b).
The curved surface is the same as the curved surface directly expanded by the outer peripheral surfaces of a) and (13b), and the pipe of the expanded portion (7a) is close to a perfect circle.

Furthermore, since the gaps (D) are arranged in phase as described above, the expanding force acts uniformly on the entire circumference of the pipe, and the wall thickness is made uniform over the entire circumference of the pipe. In addition, the pipe expansion rate is also improved.

Further, as shown in FIG. 10 (b), since the split molds (13a ...) Have short axial lengths, the point of action of the load P ₄ received from the core metal 6 at the time of pipe expanding work and the adjacent position. Maximum distance (L ₂ ) from the point of action of load P ₅ received from the split mold
Becomes shorter and the shearing force acting on the split mold becomes smaller. As a result, breakage of the split mold is prevented.

[0015]

EXAMPLE An example of the present invention shown in FIGS. 1 to 5 will be described. Reference numeral 8 is a holder, which is a hole 8 through which the core 9 is inserted in the center portion.
a is formed. A split mold holder 10 is fitted to one end of the holder 8 and fixed to the holder 8 with a screw 11. A hole 10a through which the cored bar 9 is inserted is also formed in the center of the split mold holder 10.

Reference numeral 12 denotes a split die support pin, which is screwed into a screw hole 10b formed in the front surface of the split die holder 10 and is erected forward, and four pieces are arranged at equal intervals in the circumferential direction. There is.

The split mold is divided into a plurality of parts in the axial direction of the cored bar 9. In the illustrated embodiment, the first split mold row 13 and the second split mold row 13 are separated.
It is divided into four split mold rows 14, a third split mold row 15, and a fourth split mold row 16.

The split mold of each row is divided into a plurality of pieces in the circumferential direction of the cored bar 9, and in the embodiment shown in the figure, it is equally divided into four pieces. That is, the first split mold row 13 has four fan-shaped split molds 13a to 13d in the circumferential direction, and the second split mold row 14 has four fan-shaped split molds 14a to 14d in the circumferential direction.
However, similarly, in the third and fourth split mold rows 15 and 16, four fan-shaped split molds 15a to 15d and 16a to 16d are arranged, respectively.

The outer peripheral surface of each split mold is formed so as to form a circle by combining the four split molds in each row. The split dies in each row are arranged such that the split dies in adjacent rows are in phase with each other in the circumferential direction, and the gap D between the split dies generated in each row is the gap between the split dies in the adjacent row. It is in phase with D in the circumferential direction. In the illustrated embodiment, the phases are 45 °.

In the split molds 13a, ... In the state where the split molds are arranged as described above, pin insertion holes 17 are formed so as to penetrate through the portions where the split mold support pins 12 are located. As shown in FIGS. 3 and 4, each pin insertion hole 17 is formed in an elongated hole shape that is long in the expansion / contraction direction of the split mold in which it is formed.

At the center of each split mold 13a ...
A tapered hole 18 is formed through which the cored bar 9 is inserted and which is inclined along the tapered surface 9a of the cored bar 9. Each split type 1
A circumferential groove 19 is formed on the outer periphery of 3a ...
One O is common to the four split grooves 19 in each row.
A ring 20 is fitted to urge each split mold inward.

To assemble the split molds 13a, the split molds in each row are first assembled by fitting the O-ring 20 into the groove 19. Then, the plurality of split mold rows thus combined are arranged in phase with each other by 45 ° as described above. Then, the split mold support pins 12 are inserted into the pin insertion holes 17 of the split molds 13a ... And fixed to the split mold holder 10 by screwing. As a result, each split mold 13a ... Is supported by the split mold support pin 12, and can be moved in the radial direction using the split mold support pin 12 as a guide.

Next, the expanding operation of the pipe will be described.
As shown in FIG. 2, when the cored bar 9 is retracted to the right, the split molds 13a ... Are moved in the axial direction of the cored bar 9 by the contracting force of the O-ring 20 and are tapered. Hole 18
Comes into contact with the tapered surface 9a of the cored bar 9, and the split mold 13a ...
The diameter of the circle formed on the outer periphery of the is reduced. That is, it is in the state shown by the chain line in FIGS. In this state, the expanded portion 7a of the pipe 7 is fitted to the outer peripheral portion of each split mold 13a.

Next, the cored bar 9 is advanced to the left in the figure, as indicated by the arrow A in FIG. As a result, the outer peripheral taper surface 9a pushes the split molds 13a ... outward, so that the split molds 13a .. move outward against the urging force of the O-ring 20, respectively. 3, as shown by the solid line in FIG. 4, the diameter of the circle formed on the outer circumference of the split mold 13a ... Expands. Therefore, the expanded portion 7a of the fitted pipe 7 is expanded by each split mold 13a.

At this time, the gap D formed between the split molds 13a, ... Is in phase with each other in the circumferential direction between the adjacent split mold rows, so that, for example, the first split mold row shown in FIG. 1
Horizontal component forces P _{1 and} P ₂ act on the part 7b of the pipe located in the gap D portion of _{No. 3} by the split molds 13a and 13b.
The upward force P ₃ of the split mold 14a in the adjacent second split mold row 14 shown in FIG. 4 is also transmitted.

Therefore, a part 7b of the pipe is expanded upward and becomes a curved surface equivalent to the curved surface directly expanded by the outer peripheral surface of the split mold 13a, and the circularity of the expanded portion 7a is Get higher

Further, since the gap D is in phase as described above, the expanding force of the pipe acts evenly over the entire length of the pipe, and the gap D portion does not become thin and the entire circumference is covered. The wall thickness is made uniform, and the pipe expansion ratio is also improved.

Further, the force acting on one split mold at the time of expanding the pipe is as shown in FIG.
0 (b), the maximum distance L ₂ between the point of action of the load P _{4 received} by the core metal 9 and the point of action of the load P ₅ received from the adjacent split mold is shortened, and the shear stress is reduced, resulting in the above-mentioned conventional method. There is no such breakage.

[0029]

As described above, according to the present invention, it is possible to form an expanded pipe having a high circularity with a split mold. Furthermore, the pipe wall thickness of the expanded portion can be made uniform over the entire circumference, and the pipe expansion ratio can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the assembled state.

FIG. 3 is a front view showing a split mold of a first row.

FIG. 4 is a front view showing a split mold of a second row.

FIG. 5 is a vertical cross-sectional view showing a pipe expanded state.

FIG. 6 is a vertical sectional view showing a conventional structure.

FIG. 7 is a front view showing the same split mold.

FIG. 8 is a front view showing the same expanded state.

FIG. 9 is a perspective view of a pipe expanded by a conventional structure.

10A and 10B are explanatory views of a load acting on the split mold, FIG. 10A shows a conventional split mold, and FIG. 10B shows a split mold of the present invention.

[Explanation of symbols]

 9 cores 13a, 13b ... Split mold D Gap

Claims (1)

[Claims] 1. A split die, which is divided in the circumferential direction, is arranged on the outer periphery of a taper-shaped cored bar that advances and retreats, and the split die is divided into a plurality of rows in the axial direction of the cored bar. A pipe expanding device characterized in that the gap between the split molds in each row is phased in the circumferential direction with respect to the gap between the split molds in adjacent rows.