JPS6028651B2 - Manufacturing method for polyolefin resin pipe fittings - Google Patents

Abstract

PURPOSE:To connect polyolefine seriese resin pipe of stretching jonint easily by mounting rubber pipe at socket of rigit vinyl chloride resin short pipe which is fixed inside of polyolefine series resin pipe.

Description

[Detailed Description of the Invention] Polyolefin resin pipes such as polyethylene resin pipes and polypropylene resin pipes have excellent properties, but there is no suitable adhesive for joining these pipes together. For this reason, conventionally, heat-setting or mechanical bonding had to be used, and there were problems with the workability and sealing properties of these bonds, which hindered the growth in demand for polyolefin resin pipes. .

In particular, no suitable expansion joints for polyolefin resin pipes have been found. Expansion joints with sealing rubber rings have been known for hard pinyl chloride resin pipes, but in the case of polyolefin resin pipes, molding distortion at the socket remains for a long period of time, causing damage over time. In addition, the inner dimensions of the socket processing part change, making it impossible to obtain a product with good dimensional accuracy.The polyolefin resin pipe becomes too soft when heated, making it difficult to insert it into the mold for processing the socket. Expansion joints equipped with sealing rubber rings could not be applied to polyolefin resin pipes because of problems such as bending of the joints.

The present invention is an excellent expansion joint that has a receiver □ in which a rubber ring is attached to a polyolefin resin pipe by applying a receiver □ process to a short pipe of hard vinyl chloride resin inserted and fixed with iron inside a polyolefin resin pipe. It was successful in forming the

That is, the present invention fixes a hard vinyl chloride resin short tube inside the tube end of a polyolefin resin tube with a filling adhesive, heats and softens the thus obtained two-layer tube end, and then fixes the tube end. An expanding sleeve is formed by press-fitting an inner mold with a molding ring that can expand and contract in all directions in the pipe diameter, and the inner mold and an outer mold placed outside the expanding sleeve are used to adjust the inner diameter. By expanding the molded ring, a circumferential annular bulge is formed on the sleeve after expansion, and an annular groove for storing a sealing rubber ring is formed on the inner surface of the bulge, and then the inner diameter and outer mold are This is a method for manufacturing a joint for polyolefin resin pipes, which is characterized by demolding.

Next, one example of a joint obtained by the method of the present invention will be explained based on the accompanying drawings.

FIG. 1 is a partial longitudinal sectional front view showing the state of a joint obtained by the method of the present invention upon completion of joining. As shown in the figure, a hard pinyl chloride resin short tube 2 is inserted into the inner surface of one end 1' of one of the polyolefin resin tubes 1 to be joined, and fixed with a filling adhesive 6, which is then processed with a socket. , a socket having an annular bulge 3 on the outside and an annular groove 4 on the inside, and after storing the sealing rubber ring 5 in the annular structure of this receiving □ part, the other part to be joined to the receiving □ part. The insertion end 11' of the polyolefin resin pipe 11 is inserted to complete the joint connection. Polyolefin resin pipes in the present invention include copolymer resins of olefins such as polyethylene resins, polypropylene resins, ethylene-propylene copolymer resins, olefins and relatively small amounts of other monomers (for example, vinyl acetate), etc. Examples include resin pipes made of copolymer resins such as

In addition, the hard vinyl chloride resin short pipe in the present invention includes a vinyl chloride homopolymer resin, a hard resin made of a copolymer of vinyl chloride and a small amount of other monomers (for example, ethylene, propylene, vinyl acetate, etc.) A short tube can be given.
Since the expansion joint for polyolefin resin pipes obtained by the present invention is constructed as described above, the following effects can be obtained.

It is an excellent expansion joint that can easily join '1' polyolefin resin pipes.

'2) Since the hard vinyl chloride resin pipe is inserted with iron inside the polyolefin resin pipe, the socket processing itself is easy and there is no failure.In other words, heat processing and molding during socket processing are possible. It is easy to insert into the body, and there is no risk of bending the waist in the process.

[Unlike when socket processing is applied to a 3' polyolefin resin pipe only, the dimensions of the socket □ do not change over time, and the dimensional accuracy of the socket of the joint is extremely good.
■ Since the socket is reinforced with hard PVC resin pipe, joint performance is significantly improved.

Next, the socket processing according to the method of the present invention can be carried out in various embodiments. Fig. 2 shows one aspect of the socket machining in a scale longitudinal sectional front view of the mold and the socket part during the socket machining.
The same thing as in the figure is shown. Moreover, FIG. 3 is a sectional view taken along the line AA of the inner mold. First, polyolefin resin pipe 1
A hard vinyl chloride resin short pipe 2 is inserted into the pipe end 1' of the pipe, fixed with a filling adhesive 6, and then heated and softened separately.
The inner mold 21 is inserted into this to expand it and form it into an enlarged diameter sleeve. Next, an outer mold 22 that regulates the outer shape of the annular bulge 3 to be molded is placed on the outside of the expanded sleeve (this state is shown in the upper half of FIG. 2 and the upper half of FIG. 3). ). After that, when the conical body 24 attached to the inner mold 21 is moved to the back side of the tube 1, this conical body 2
This is because the molded ring 23 (which is made up of fan-shaped segments 23' and 23j connected by a spring 25) engaged with the curved surface of No. 4 expands radially outward in the direction of the tube. , an annular bulge 3 is formed on the outside of the broadside sleeve, and at the same time an annular groove 4 for accommodating a sealing rubber ring is formed on the inside (this state is shown in the lower half of Figure 2 and the lower half of Figure 3). (shown in the bottom half of the figure). Note that the filling adhesive 6 (for example, rubber adhesive) is used in the polyolefin resin tube 1.
This is to maintain watertightness between the tube end 1' and the hard pinyl chloride resin short tube 2. Generally, it is difficult to firmly bond a polyolefin resin pipe and a hard vinyl chloride resin pipe, but in the method of the present invention, the exchange is mechanically fixed at the annular bulge 3, and there is no risk of it coming off.
As described above, according to the method of the present invention, a hard vinyl chloride resin short tube is fixed inside the tube end of a polyolefin resin tube with a filling adhesive, and the two-layer tube end thus obtained is integrally expanded. Since the tube end is made of hard vinyl chloride short tube with high shape retention, it retains its original shape even when heated and softened, making it easy to insert the inner mold. The tube end does not bend (seat) when inserting the mold.

In an embodiment of connecting polyolefin resin pipes using the joint obtained by the present invention, one end of the polyolefin resin pipe to be connected is made into a pipe joint by the method of the present invention, the other end is left as is, and such resin pipes are connected in sequence. Alternatively, a connecting pipe with joints formed at both ends of a polyolefin resin pipe (short pipe or long pipe) by the method of the present invention may be prepared, and such a connecting pipe and a normal polyolefin resin pipe may be connected. may be connected alternately.

[Brief explanation of the drawing]

Fig. 1 shows an example of a joint obtained by the method of the present invention as a partial longitudinal sectional front view after joining is completed, and Fig. 2 shows an example of the joint formed by the method of the invention in a longitudinal section. It is shown in a front view, and FIG. 3 is a sectional view taken along line A-A of the inner mold 21 in FIG. The main symbols in the figure are as follows. 1: polyolefin resin pipe, 1': end of the pipe, 2: hard vinyl chloride resin short pipe, 3: annular bulge, 4: annular groove, 5 rubber rings for sealing, 6: filling adhesive, 11: Polyolefin resin pipe, 11': Insertion end of the pipe, 21: Inner mold, 22
: Outer mold, 23: Molded ring, 24: Cone. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A hard vinyl chloride resin short tube is fixed inside the tube end of the polyolefin resin tube with a filling adhesive, and after heating and softening the thus obtained two-layer tube end, the tube diameter is attached to the tube end. An expanding sleeve is formed by press-fitting an inner mold having a molding ring that can expand and contract in the direction, and the molding ring of the inner mold is further formed using the inner mold and an outer mold disposed outside the expanding sleeve. By expanding the diameter of the sleeve, a circumferential annular bulge is formed in the expanded diameter sleeve, and an annular groove for storing a sealing rubber ring is formed on the inner surface of the bulge, and then the inner and outer molds are removed. A method for manufacturing a pipe fitting for polyolefin resin pipes, which is characterized by: