JPS60107322A - Molding method of socket - Google Patents

Abstract

PURPOSE:To make a thickness of a socket having an expanded diameter to be made about equal with or larger than that of an original pipe, by a method wherein an end part of a synthetic resin pipe is thicknened on both of the sides in an external and internal directions and the diameter of the thickened sides are expanded. CONSTITUTION:An annular protruded part 11 is formed by pressing an end part of a synthetic resin pipe 1, which are made to heat and soften, in a cavity constituted with an outer and inner dies 2, 3. Then the other end part of the synthetic resin pipe 1 is made to fit to an outer wall surface of an expanding part 51 while the diameter of the same is being expanded by pressing the same and pushing up a thickened part to a tapered surface 4. A mold core 52 is made to protrude from the expanding part 51 by making a tapered components 53 slide further and pressed against a pressing die 6 by expanding the diameter of the annular protruded part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a socket forming method that allows the wall thickness of the expanded diameter socket to be equal to or greater than the wall thickness of the original pipe.

When a mold is press-fitted into one end of a synthetic resin pipe to form an enlarged diameter socket, the wall thickness of the socket will inevitably decrease and become thinner than the original pipe wall thickness, resulting in poor pressure resistance and impact resistance. There is a problem with the decline.

Therefore, one end of the synthetic resin pipe that will become the socket has been thickened in advance, and the diameter of the thickened part has been expanded. Since the method was to restrict the thickness by mold and increase the thickness only in the outer circumferential direction, there was a limit to the amount of thickness that could be increased.

Therefore, when an enlarged diameter socket is formed by press-fitting a mold into the end of a thickened pipe using the conventional method, the internal thickness of the socket is not thinner than the original pipe wall thickness, especially when the diameter expansion ratio is maximized. The problem was that the groove for attaching the rubber ring was thin.

The present invention eliminates the drawbacks of such conventional methods, and in the thickening step, the synthetic resin pipe is thickened in the outer circumferential direction and the inner circumferential direction, and the wall thickness is further increased in the outer circumferential direction or the inner circumferential direction. In the first diameter expansion process, a mold was press-fitted into the thickened part to form a socket, and the diameter of the annular projection was expanded to provide a groove for attaching a rubber ring. The feature lies in the socket molding method.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing the molding process of the present invention, with the upper half showing the state before the thickening process and the lower half showing the state after the thickening process.

In the figure, / is a synthetic resin pipe made of thermoplastic resin such as vinyl chloride resin or polyethylene resin, λ is an outer mold, and 3 is an inner mold, and the rear of the inner mold 3 is molded through a tapered surface. Type!
is provided.

The outer mold has a cylindrical body that is divided into several parts and is configured to be able to expand and contract in diameter.
2- is provided. The inner wall surface of the outer mold 3 has a diameter dimension that creates a gap T between it and the outer peripheral surface of the synthetic resin pipe when the diameter is reduced and the mold is clamped, while the outer wall surface of the inner mold 3 is
The diameter is dimensioned to provide a gap T2 between the synthetic resin pipe and the inner circumferential surface of the pipe.

The gap TI + T2 is the part where the pipe wall thickness increases when one end of the synthetic resin pipe is pushed and filled into the cavity consisting of the outer mold 3 and the inner mold 3. T1
It is preferable to make it slightly larger.

3/ is an annular groove provided in the inner mold 3, and the groove 3/
are provided corresponding to the positions where rubber and groove mounting grooves are formed during the diameter expansion process.

This groove 3 must necessarily be provided in the inner mold 3.
As shown in Figure 1 by the broken line marked 2/,
It may also be provided on the outer mold.

Molding mold! is a continuous enlarged part from the tapered surface! / and a molded core divided into multiple pieces! 2 and the enlarged part of the core j2! A tapered member that appears from /! From 3 onwards, a suppression mold B is disposed on the outside of the mold j.

Next, the thickness increasing step and diameter expanding step of the molding method of the present invention will be explained based on FIG. 1.

First, in the thickening step, one end of one synthetic resin pipe is heated and softened over a predetermined width, and the one end of the pipe is pushed into a capity constituted by a clamped outer mold and inner mold 3.

Due to this suppressing action, the wall thickness of one end of the synthetic resin pipe increases in the outer circumferential direction and the inner circumferential direction. and closely adheres to each wall surface of the inner cover 3. Then, the softened resin filling the groove 3/ of the inner mold 3 forms an annular convex portion // whose thickness is further increased.

In addition, this annular convex part will be formed to protrude to the outer peripheral side when the outer mold part is provided with a concave groove part. ' During this thickening process, the outer mold 2. The inner mold 3 is heated by circulating a heating medium or by a heater (not shown) K, and the thickened portion of the synthetic resin pipe is maintained at a temperature suitable for the next diameter expansion molding.

After the thickening process is completed, the outer mold is opened as shown in the lower half of FIG.

In the next diameter expansion process, the other end of the synthetic resin pipe is pressed, and the thickened part is pushed up into the tapered surface, increasing the diameter and making it fit the outer wall surface of the enlarged part. After that, Taper Abduction 53
Slide the molded core! B is made to protrude from the enlarged part S/, the diameter of the annular convex part // of the thickened part is expanded, and the press die g is pressed.

In this way, a socket having a groove for attaching a rubber ring is formed.

As detailed above, the socket molding method of the present invention includes the steps of increasing the thickness of one end of the synthetic resin tube and expanding the diameter of the increased thickness. Since the wall is increased in both the outer and inner circumferential directions, the wall can be made twice as thick compared to the conventional method, which increases the wall thickness only in the outer circumferential direction. When the socket is molded using this method, the wall thickness of the socket can be made equal to or greater than the thickness of the original tube. Moreover, in the part of the rubber groove installation groove where the diameter expansion rate is maximum and the reduction is significant, an annular convex part with an increased wall thickness is formed, so that the rubber groove installation groove part also has the same thickness as the original pipe. A socket with excellent pressure resistance and impact resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the molding process of the present invention, with the upper half showing the state before the thickening process and the lower half showing the state after the thickening process. C... Synthetic resin pipe, //... Annular convex part... Outer mold,
3...Inner mold, 3/...Annular groove...Tapered surface,
! ...Molding mold

Claims (1)

[Claims] One end of the synthetic resin pipe softened by heating is forced into a cavity consisting of an outer mold and an inner mold to form the desired wall thickness, and a mold is press-fitted into the thickened part to receive the expanded diameter. In addition to the step of forming the mouth, in the thickening step, the thickness of the synthetic resin pipe is increased in the outer circumferential direction and the inner circumferential direction, and an annular convex portion whose wall thickness is further increased in the outer circumferential direction or the inner circumferential direction is formed. and in the next diameter expansion step, a mold is press-fitted into the thickened portion to form a socket, and the annular convex portion is expanded in diameter to provide a groove for attaching a rubber ring. Mouth shaping method.