JPH0376208B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to a synthetic resin pipe (hereinafter referred to as a hole pipe) having no unevenness at the end thereof, which is formed by having a large number of through holes extending in the pipe axis direction through the pipe wall. The present invention relates to a method of forming an enlarged diameter socket with excellent sealing properties.

[Prior art]

Conventionally, many methods have been proposed for forming an enlarged-diameter socket at the end of a hole pipe, but in forming the enlarged-diameter socket of a hole pipe, the through hole is formed by the difference in wall thickness between the pipe wall and the hole and wall. Due to the difference in the degree of tension and the change in shrinkage after processing, the through hole is crushed and the pipe wall in that part is dented, creating unevenness on the inner circumferential surface of the enlarged diameter part, causing problems in performance such as sealing performance.

For this reason, there are methods that pressurize fluid into a large number of continuous holes along the pipe axis of the tube wall to form the enlarged diameter socket, and vacuum forming methods that mold the inner surface of the enlarged diameter socket. A molding method has been used in which the mold surface is brought into close contact with the mold surface to eliminate unevenness, but this requires a special air pressure device or vacuum device, which inevitably increases costs.

[Purpose of the invention]

The present invention does not use the above-mentioned means, but when forming an enlarged-diameter socket at the end of a hole tube, a short tube is placed inside the end of the hole tube to expand the diameter, thereby preventing unevenness and improving sealing performance. It is an object of the present invention to provide a method for forming an enlarged diameter socket of a hole pipe, which improves the performance.

[Structure of the invention]

In order to achieve the above object, the present invention provides a method for forming an enlarged diameter socket in a synthetic resin hole tube having a large number of through holes in the tube axis direction in the tube wall. A solid short pipe having a diameter and a length corresponding to the length of the expanded diameter socket,
A sealing material is placed inside the end of the hole tube, and after the hole tube and the solid short tube are heated and softened, an inner mold is inserted from inside the solid short tube to seal the end of the hole tube and the solid short tube. The solid short tube is integrally expanded in diameter, and the inner surface of the socket portion is formed by the expanded diameter solid short tube.

〔Example〕 Embodiments of the present invention will be described below based on the drawings.

The hole tube 1 has a large number of through holes 1a formed in the tube wall in the tube axis direction, and the enlarged diameter socket is first formed as shown in FIG. A regular solid short tube 2 made of synthetic resin having a length corresponding to at least the length of the enlarged diameter socket to be formed is provided with rubber gaskets 3a and 3b inside the end of the hole tube 1. Interpose and interior. At this time, it is preferable to wrap the rubber gaskets 3a, 3b around the outer periphery of the short tube 2 in advance and then insert them into the inside of the hole tube 1, since this makes it easier to insert the rubber gaskets 3a and 3b.

In this state, the tube end of the hole tube 1 and the short tube 2 are heated to the softening temperature of the synthetic resin constituting them, thereby softening the socket portion 4.

Next, in this state, an inner mold (not shown) is inserted from the inside of the solid short tube 2 to integrally expand the diameter of the end of the hole tube 1 and the solid short tube 2, as shown in FIG. , an enlarged-diameter socket part 7 having an inclined part 5 and a large-diameter socket part 6 is formed by a solid short pipe whose diameter has been enlarged.

By applying an adhesive (not shown) to the inner periphery of the large-diameter socket 6 formed as described above and fitting the connecting pipe 8, the enlarged-diameter socket 7 and the connecting part 8 will be watertight. Joined.

FIG. 3 shows another embodiment of the present invention, in which the enlarged diameter socket 7 is formed using a mold (not shown) consisting of an inner mold and an outer mold in a softened state as in the previous embodiment. form. During this molding, an annular groove 9 is formed in the socket portion 7. Then, a rubber ring 10 is placed in the annular groove 9.
The rubber ring 1 is fitted as shown by the two-dot chain line in FIG.
When the connecting tube 8 having a diameter slightly larger than the zero inner diameter is fitted by pressing the rubber ring 10, the connecting tube 8 is joined via the rubber ring 10 in a flexible and watertight manner.

FIG. 4 shows still another embodiment of the present invention. In the embodiment shown in FIG. 2, rubber packings 3a and 3b were interposed between the hole tube 1 and the short tube 2, but In this embodiment, instead of the rubber gaskets 3a and 3b, a rubber tube 11 is interposed over substantially the entire area between the hole tube 1 and the short tube 2 forming the enlarged diameter socket. When the rubber tube 11 is used in this way, the sealing effect between the hole tube 1 and the short tube 2 is further increased, and the occurrence of unevenness on the inner circumferential surface of the enlarged diameter socket 7 can be further prevented. It becomes possible to mold the enlarged diameter socket part 7 which has an excellent sealing effect with the connecting pipe 8.

Furthermore, in the embodiment shown in FIG. 4, an adhesive may be used instead of the rubber tube 11.

〔Effect of the invention〕

As described above, in the present invention, a short solid tube having an outer diameter smaller than the inner diameter of the Hall tube and a length corresponding to the length of the enlarged diameter socket is inserted into the Hall tube through a sealing material. After heating and softening the inside of the end, an inner mold is inserted from the inside of the solid short tube to expand the diameter of the end of the hole tube and the solid short tube integrally, and the short tube has an expanded diameter. This forms the inner surface of the enlarged diameter socket.
There are no irregularities on the inner circumferential surface of the enlarged diameter socket, and the sealing function can be fully performed.

Moreover, since the sealing material is also interposed between the hole pipe and the short pipe, a sealing function can be achieved.

[Brief explanation of drawings]

Figures 1 and 2 show one embodiment of the present invention. Figure 1 is a cross-sectional front view of a hole pipe with a rubber packing interposed and a short pipe set, and Figure 2 is an enlarged diameter socket. FIG. 3 is a cross-sectional front view of an enlarged-diameter socket fitted with a rubber ring of another embodiment, and FIG. 4 is a cross-sectional front view of an enlarged-diameter socket fitted with a rubber tube of another embodiment. FIG. 1 is a hole pipe, 1a is a through hole, 2 is a short pipe, 3a,
3b is a rubber gasket, 5 is an inclined portion, 6 is a large diameter socket, 7 is an enlarged diameter socket, 9 is an annular groove, 10 is a rubber ring, and 11 is a rubber tube.

Claims (1)

[Claims] 1. A method of forming an enlarged diameter socket in a synthetic resin hole pipe having a large number of through holes in the pipe axial direction in the pipe wall, wherein the enlarged diameter socket has an outer diameter smaller than the inner diameter of the hole pipe. A short solid tube having a length corresponding to the length of the hole tube is placed inside the end of the hole tube through a sealing material, and then the hole tube and the solid short tube are heated and softened, and then the solid short tube is heated and softened. It is characterized by inserting an inner mold from the inside of the short tube to integrally expand the diameter of the end of the hole tube and the solid short tube, and forming the inner surface of the socket with the expanded diameter solid short tube. A method for forming the enlarged diameter socket of a hole pipe.