JPH057951A - Manufacture of socket part for metallic tube and composite tube and die used therefor - Google Patents

Abstract

PURPOSE:To manufacture a socket part having no variance in the inside diameter of the opening end by reducing the diameter of the opening end side in the diameter tube end part of a metallic tube or a composite tube. CONSTITUTION:At the time of manufacturing a socket part by reducing the diameter of an opening end 2b side in a diameter tube end part 2a of a tube 2, and allowing its opening end 2b to abut on a columnar core part 5a of an inner die 5, the end face of the opening end concerned 2b is subjected to closing-in to a prescribed state, even in the case a projecting part or ruggedness caused by a weld zone, etc., exists in the end face of the opening end 2b by using a die 1 having a prescribed clearance C which becomes an opening end escape part between the inside peripheral surface of a second outer die 4 having a diameter reducing recessed part 4a and the columnar core part 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a receiving portion having an opening end with a predetermined inner diameter by reducing the diameter of the opening end side of a metal pipe end portion or a composite pipe end portion whose diameter has been expanded in advance. Regarding the mold used for.

[0002]

2. Description of the Related Art For example, in a metal pipe used as a piping material for a building or a composite pipe in which the inner surface of the metal pipe is coated with a corrosion-resistant synthetic resin, a receiving end for connecting another pipe is provided at the end of the pipe. It is formed. For this type of receptacle, the pipe end of a metal pipe or composite pipe should be expanded by rubber bulge molding, etc., and then the opening end side of the expanded pipe end should be reduced to a specified diameter. Is formed by.

As a method of performing the above-described diameter reduction processing after the diameter of the pipe end is enlarged, there is a technique described in, for example, Japanese Patent Laid-Open No. 130127/1990. As shown in FIG. 9, after the end portion 100a of the pipe 100 is expanded to a predetermined diameter, the opening end 100b side of the pipe end portion 100a is press-fitted into the recess 101a of the inner diameter-reducing mold 101, Its open end 100
The end surface on the b side has a cylindrical core portion 1 having a predetermined diameter in the recess 101a.
02 is to be brought into contact with. According to this, the diameter of the expanded pipe end 100a is press-fitted into the recess 101a on the side of the opening end 100b, so that the diameter is reduced to a predetermined shape along the inner surface of the recess 101a.

[0004]

However, when the material of the metal pipe or the composite pipe is, for example, an electric resistance welded pipe (a pipe formed by forming a metal strip into a circular shape and then welding the joints thereof), the above-mentioned problem occurs. According to such a conventional diameter reduction method, the following problems occur. That is, when the diameter of the electric resistance welded pipe is expanded, the welded part is harder than the non-welded part and is less likely to be expanded during the diameter expansion.Therefore, the welded part is formed on the end face on the opening end side of the pipe end after the diameter expansion. Appears as a convex portion. Further, when the pipe to be expanded in diameter has an uneven thickness, that is, when there is a portion having a large wall thickness and a portion having a small wall thickness, the end face on the opening end side of the pipe end portion of the expanded diameter has unevenness depending on the thickness.

When the diameter of the pipe end surface having such a convex portion or unevenness is reduced by the method described in the above publication, the convex portion or the like hits the core portion 102, and the inner diameter of the diameter reduction processing is performed. Since it is regulated, the diameter cannot be reduced to a predetermined inner diameter. Therefore, if the insertion part of the other tube is inserted into the receiving part as it is, a relatively large gap is created between the inner surface of the receiving part and the outer surface of the insertion part, which may result in unstable joining. become.

The present invention addresses the above-mentioned problems when manufacturing the receiving portion by reducing the diameter of the opening end side of the expanded pipe end of the metal pipe or the composite pipe. It is an object of the present invention to obtain a receiving portion having an opening end with a uniform or substantially uniform inner diameter dimension by a diameter reducing process even if the opening end of the portion has some projections and depressions.

[0007]

In order to achieve the above object, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) is
It is characterized by being configured as follows. That is, the opening end side of the expanded pipe end of the metal pipe or the composite pipe is reduced in diameter, and the opening end is brought into contact with a cylindrical core portion having a predetermined diameter to form a receiving portion having an opening end having a predetermined inner diameter. In the method of manufacturing, the opening end side is reduced in diameter in a state in which there is a clearance for the opening end in front of the opening end when the opening end comes into contact with the cylindrical core portion.

The invention according to claim 2 of the present application (hereinafter,
The second invention) is a mold used for carrying out the first invention, and is characterized by having the following configuration. That is, an outer mold having a concave portion whose diameter gradually decreases from one end face toward the inner depth so that the opening end side of the expanded pipe end portion in the metal pipe or the composite pipe can be reduced to a predetermined shape, An inner mold having a cylindrical core portion of a predetermined diameter arranged inside the outer mold so that the diameter-opened end may come into contact with the outer mold and restricting the end face position of the opening end when the diameter is reduced; Between the outer peripheral surface of the core of the mold and the inner peripheral surface of the outer mold, there is a clearance for the open end in front of the open end when the open end contacts the core. A predetermined clearance is provided in at least a part of the direction.

This clearance is, for example, as shown in FIG. 5 or FIG.
The inner mold 1 set in the outer mold 14, 24 as shown in FIG.
5 and 25 cylindrical core portions 15a and 25a, and the expanded pipe end portion 1
When the open ends 12b and 22b of the open ends 2a and 22a come into contact with each other, the escape portions (a) and (b) for the open ends can be secured in front of the open ends 12b and 22b (to the right in the state of the same figure). Anything is sufficient.

In the above-mentioned mold, the tip angle of the inner surfaces of the recesses of the outer molds 14 and 24 (the angle between the inner surface at the small-diameter end of the outer mold recesses and the pipe axis direction) is in the range of 20 ° to 80 °. It is effective for processing the open end of the expanded pipe end. Further, the length of the relief portions (a) and (b) secured on the inner side of the clearance (relief allowance) is at least (1/2) or more of the wall thickness of the end portion of the expanded pipe subjected to diameter reduction processing. Is desirable. Further, it is desirable that the clearance is set to be equal to or less than the wall thickness of the end portion of the expanded diameter pipe and within a range of about (1/2) or more.

In the case of the outer mold 14 as shown in FIG. 5,
The angle α formed by the inner surface of the inner mold 15 on the inner side of the small diameter end of the recess is arbitrary.

[0012]

According to the above construction, even if the opening end of the expanded pipe end of the metal pipe or the composite pipe has a convex portion due to a welded portion or unevenness due to uneven thickness, the inner diameter is uniform or substantially uniform as follows. A receptacle having a uniform open end will be obtained. That is, first, when the opening end side of the expanded diameter pipe end is press-fitted into the recess from the one end face side of the outer mold, the opening end side is reduced in diameter along the inner surface shape of the recess, and the inside It abuts on the inner cylindrical column portion arranged at. In this state, the convex portion existing on the end surface of the opening end only contacts the core portion, and the inner peripheral side of the opening end does not contact the core portion over the entire circumference.

Thereafter, by further reducing the diameter in this state, the enlarged diameter shoulder portion of the pipe, that is, the portion of the pipe between the enlarged diameter portion and the non-expanded portion (parallel portion) is subjected to the reduction processing. At the same time, the same force acts on the open end to crush the end face. In that case, since there is a relief part in front of the opening end, the opening end escapes toward the relief part in front of the opening end according to the magnitude of the force to crush the end face of the opening end. More easily crushed. as a result,
Even if the above-described convex portion is present on the end surface of the opening end to be reduced in diameter, the end surface is relatively easily crushed by the force of the crushing process. As a result, it is possible to obtain a receptacle having an open end with a uniform or substantially uniform inner diameter.

[0014]

EXAMPLES Examples of the present invention will be described below. First, the mold used in this embodiment will be described. As shown in FIG. 1, a mold 1 includes a first outer mold 3 used for expanding the diameter of a pipe end 2a of an electric resistance welded steel pipe (hereinafter referred to as a pipe) 2 which is a metal pipe,
From the second outer mold 4 for diameter reduction that reduces the diameter of the expanded end 2a of the pipe end 2a into a predetermined shape, and the inner mold 5 fitted and set in the second outer mold 4. Become.

Of these, the first outer mold 3 has an opening 3 at one end.
The tube end portion 2a having the diameter b is expanded from the opening portion 3b so that the opening end 2b side of the pipe end portion 2a protrudes by a predetermined amount. In addition, the second outer mold 4 has a recess 4a whose diameter gradually decreases from the end face facing the first outer mold 3 toward the inner depth, and the diameter-expanded pipe end 2a extends along the inner surface of the recess 4a. By press-fitting the opening end 2b side, the opening end side is reduced in diameter to a predetermined shape.

On the other hand, the inner die 5 has a cylindrical core portion 5a having an outer diameter smaller than the diameter-expanded tube end portion 2a by a predetermined amount, and the end surface of the core portion 5a has a core portion 5a when the diameter is reduced on the opening end 2b side. The second outer mold 4 is concentrically provided so as to abut the outer surface. Between the core portion 5a of the inner die 5 and the small-diameter end of the recess 4a of the second outer die 4, when the open end 2b comes into contact with the outer surface of the core portion 5a, the relief is provided in front of the open end. A predetermined clearance C is provided so that the portion exists (see FIGS. 2 and 4).

The clearance C has a fixed length along the axial direction from the position of the small-diameter end of the recess 4a to the inner side thereof.
That is, it has an escape margin A. The radial dimension of the clearance C and the clearance in the mold 1 used in this embodiment are both 1.5 mm, and the angle θ between the inner surface of the small-diameter end of the second outer die recess 4a and the axial direction is It is 45 °.

The method of this embodiment using such a mold is
Do the following: First, as shown in FIGS. 1 and 2, in a state in which the opening end 2b side of the expanded diameter pipe end 2a of the pipe 2 is projected from the opening 3b of the first outer mold 3 by a predetermined amount,
By bringing the second outer die 4 relatively close to the first outer die 3, the diameter-expanded pipe end opening end 2b is inserted into the recess 4a of the second outer die 3.
Press in the side.

In this way, the expanded diameter pipe end opening end 2b
The opening end 2b abuts the outer surface of the cylindrical core portion 5a of the inner mold 5 while the side is reduced in diameter along the inner surface of the second outer mold recess 4a. At this time, there is a predetermined clearance C in front of the abutting open end 2b. Next, with the clearance C existing in the predetermined position, the core portion 5a is
After abutting the diametrically expanded tube end opening end 2b on the diametrically expanded tube end, the two dies 3 and 4 are brought closer to each other by a predetermined amount without interruption, so that the diametrically expanded tube end is closed as shown in FIGS. The opening end 2b side is reduced in diameter until a constant crushing force acts on the end face of the opening end 2b.

According to such a configuration, the opening end 2b side of the diameter-expanded tube end portion 2a protruding from the opening portion 3b of the first outer die 3 has the second outer die 4 as shown in FIGS. By being press-fitted into the concave portion 4a, the diameter is reduced along the inner surface of the concave portion 4a. When the expanded pipe end opening end 2b hits the outer surface of the cylindrical core portion 5a of the inner mold 5 when pressed into a predetermined position, the outer molds 3 and 4 are relatively moved by a predetermined amount in that state. By being brought close to each other, the enlarged diameter shoulder portion 2d located between the parallel portion 2c of the pipe 2 and the enlarged diameter pipe end portion 2a.
Is subjected to drawing processing, and the same amount of force is applied to the open end 2
The force to crush this acts on b.

At this time, if there is a relatively hard protrusion (not shown) due to, for example, a welded portion at the opening end 2b, the protrusion is formed on the outer surface of the cylindrical core portion 5a before other portions. Since the protrusions come into contact with each other and normally serve as supports, the diameter-expanding shoulder portion 2d is reduced in diameter before the inner peripheral surface side of the opening end 2b abuts the core portion 5a over the entire circumference. However, in the above configuration, the two outer molds 3 and 4 are relatively moved by a predetermined amount with a predetermined clearance C provided between the cylindrical core portion 5a and the small diameter end of the second outer mold recess 4a. When a force for crushing the convex portion at the opening end 2b is applied, the front clearance C serves as an escape portion for the opening end 2b, as shown in FIGS. 3 and 4. To work.

Therefore, the convex portion existing at the opening end 2b is more likely to be crushed as compared with the case where there is no such escape portion. As a result, the convex portion of the opening end 2b is relatively easily crushed by the force acting when the diameter expansion shoulder 2d is reduced in diameter, and the inner peripheral side of the opening end 2b comes into contact with the core portion 5a over the entire circumference. . As a result, it is possible to extremely reduce the variation in the inner diameter of the expanded diameter pipe end opening end 2b after the diameter reduction, and it is possible to obtain a receiving portion having an opening end with a substantially constant inner diameter.

It should be noted that according to the method of this embodiment, the 2.0 mm convex portion due to the welded portion was formed at the open end of the expanded diameter pipe end portion until the outer diameter was changed from 132 mm to 115 mm. When the diameter reduction processing was performed, the variation in the inner diameter of the opening end was within the range of 115 mm + 0.50 mm. On the other hand, as a comparative example, for a pipe 52 having the same structure as the pipe used in the above-mentioned embodiment, a mold 51 (a cylindrical core portion 55 of a second outer mold 54 and an inner mold 55) as shown in FIGS.
Clearance c with a is 1.5 mm, clearance is 0 mm,
When the diameter reduction processing was performed using the angle θ of the inner surface of the small-diameter end of the second outer mold recess 54a), the variation in the inner diameter of the expanded-diameter pipe end open end 52b was 115 mm + 1.30 mm.

From these measurement results, according to the present embodiment, the variation in the inner diameter of the opening end is 0.8 as compared with the comparative example.
It was found that the size was reduced by 0 mm.

[0025]

As described above, according to the present invention, the diameter of the opening end side of the expanded pipe end of the metal pipe or the composite pipe is reduced to manufacture the receiving portion having the predetermined inner diameter at the opening end. In this case, since a predetermined escape portion for the opening end is ensured between the inner mold that abuts the opening end and the outer mold outside thereof,
The variation in the inner diameter of the open end can be extremely reduced.

As a result, the inner diameter of the tip of the receiving end of the pipe can be made closer to the outer diameter of the other pipe insertion portion, and the centering of the piping line is facilitated.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which a pipe and an inner mold are set in a predetermined state in an outer mold (second outer mold), and the diameter-expanded end of the pipe is reduced in diameter. FIG. 4 is an axial longitudinal cross-sectional view of the periphery of a pipe end portion showing a state in which it is performing.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a longitudinal sectional view in the axial direction of the periphery of the pipe end portion showing a state in which the opening end side of the expanded diameter pipe end portion is contracted to the final state in the same embodiment.

FIG. 4 is an enlarged view of a main part of FIG.

FIG. 5 is an enlarged longitudinal cross-sectional view of a main portion around a cylindrical core portion used for explaining the mold according to the second invention of the present application.

FIG. 6 is an enlarged longitudinal cross-sectional view of a main portion around another cylindrical core portion used for explaining the same mold according to the second invention of the present application.

FIG. 7 is a longitudinal cross-sectional view in the axial direction around the end portion of the expanded tube showing the method for manufacturing the socket and the mold used in the method according to the comparative example.

FIG. 8 is an enlarged view of a main part of FIG.

FIG. 9 is a vertical cross-sectional view of a pipe end and its periphery showing an example of a conventional method for manufacturing a receiving portion of a composite pipe.

[Explanation of symbols]

1 ... mold 2 ... Pipe (ERW pipe), 2a, 12a, 22a ... end of expanded pipe, 2b, 12b, 22b ... open end, 4, 14, 24 ... Outer mold (second outer mold), 4a: concave portion, 5,15,25 ... Inner mold, 5a: cylindrical core portion, C ... clearance, (A), (b) ... Escape part.

Claims (2)

[Claims] 1. An opening end side of a diameter-expanded pipe end of a metal pipe or a composite pipe formed by coating an inner surface of the metal pipe with a synthetic resin is contracted so that the opening end contacts a cylindrical core portion having a predetermined diameter. In a method of manufacturing a receptacle having an open end having a predetermined inner diameter by contacting with each other, when the open end is in contact with a cylindrical core part, a relief part for the open end is present in front of the open end. A method for manufacturing a receiving portion of a metal pipe / composite pipe, characterized in that the opening end side is reduced in diameter in the state of being set. 2. A mold for use in a method for manufacturing a receiving part by reducing the diameter of the opening end side of the expanded diameter pipe end of a metal pipe or a composite pipe formed by coating the inner surface of the metal pipe with a synthetic resin. The outer die having a concave portion whose diameter is gradually reduced from one end surface toward the inner depth so that the opening end side of the expanded diameter pipe end can be reduced in a predetermined shape, and the opening end to be reduced in diameter are in contact with each other. And an inner die having a cylindrical core portion having a predetermined diameter that is arranged inward of the outer die so as to be able to contact and regulates the end face position of the opening end when the diameter is reduced, and the outer peripheral surface of the core portion of the inner die. Between the inner peripheral surface of the outer die and the inner peripheral surface of the outer die, at least a part in the circumferential direction is determined so that when the opening end contacts the core portion, there is a relief portion for the opening end in front of the opening end. The mold is characterized by the clearance of.