JPH07205193A - Manufacturing method of pipe with socket - Google Patents

Abstract

(57) [Summary] [Structure] The cavity 12 is formed by mounting the pipe 12 'and the magnetic alloy heater 16 on the inner mold 18 and closing the outer mold 20. Then, hot air is blown from the hot air generator 57 into the cavity 32 to heat the tip of the pipe 12 'to near the melting point. After that, a moldable material is injected into the cavity 32, cooled and solidified, and then the outer mold 20 is opened to remove the pipe with a socket. [Effect] By heating the tip end of the pipe 12 ′ with hot air to thermally expand it, the gap between the pipe 12 ′ and the inner mold 18 and the outer mold 20 can be sealed, and leakage of the moldable material can be prevented. Further, the fusion property between the pipe 12 'and the moldable material can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a pipe with a socket, and more particularly to a method for manufacturing a pipe with a socket having a socket such as a rubber ring socket, an adhesive socket or an electric fusion socket.

[0002]

2. Description of the Related Art An example of a method for manufacturing a pipe with a socket of this type is disclosed in PCT / JP92 / 01733. In this conventional technology, (a) a pipe and a heating element unit are attached to the inner mold, (b) an outer mold is joined to the inner mold to form a cavity, and (c) a moldable material is injected into the cavity. It is intended to manufacture a pipe having a receptacle having a heating element unit provided on the inner surface thereof.

[0003]

In the prior art, a gap is created between the pipe mounted in the inner die and the inner die or the outer die, and the moldable material injected into the cavity may leak from this gap. was there. In addition, there is a problem that the injection-molded receptacle and the pipe body are poor in bondability.

Therefore, a main object of the present invention is to provide a method for producing a pipe with a socket, which can prevent leakage of the moldable material and improve the bondability between the pipe body and the socket.

[0005]

According to the present invention, (a) a pipe is attached to an inner mold, (b) an outer mold is joined to the inner mold to form a cavity, and (c) hot air is blown into the cavity. The end of the pipe to near the melting point, (d) closing the hot air path,
(e) A method of manufacturing a pipe with a socket, in which a moldable material melted in a cavity is injected to form a socket at an end of the pipe.

[0006]

When the hot air is sent into the cavity to heat the end of the pipe to the vicinity of the melting point, the end of the pipe is thermally expanded and the pipe and the inner mold and the outer mold are brought into close contact with each other. Therefore, the gap between the pipe and the inner mold or the outer mold is completely sealed, and leakage of the moldable material injected into the cavity is prevented.
Also, by heating the end of the pipe to near the melting point, the fusion between the end of the pipe and the moldable material is improved,
The bondability between the pipe body and the receiving port is improved.

[0007]

According to the present invention, it is possible to prevent the moldable material injected into the cavity from leaking out and to improve the bondability between the pipe and the receiving port. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pipe 10 with a socket manufactured by the manufacturing method of this embodiment shown in FIG. 1 includes a pipe body 12 made of a synthetic resin such as polyethylene or polybutene. An enlarged diameter receiving port 14 is formed at the end of the pipe body 12, and a net-like magnetic alloy heater 16 as shown in FIG. 2 is provided at or near the inner peripheral surface of the receiving port 14. This pipe with a socket 10 is used for fusion-bonding both pipes by inserting another pipe into the socket 14 and applying a current to the magnetic alloy heater 16 using electromagnetic induction.

Such a pipe 10 with a socket is manufactured by using an inner mold 18 and an outer mold 20 as shown in FIG. The inner mold 18 includes a substantially cylindrical pipe mounting portion 22.
The tip of the pipe mounting part 22 is chamfered in a taper shape so that the pipe 12 'can be easily mounted, and the inner part of the pipe mounting part 22 is tapered so that the end of the pipe 12' can be expanded. The diameter is expanded. Then, the heater mounting portion 26 is formed by further expanding the diameter from a position separated from the tapered diameter expanded portion 24 by a predetermined distance.
The connecting surface 2 which is further expanded from 6 and is connected to the outer die 20.
8 is formed.

The outer die 20 includes a first die 20a and a second die 20b which are opened and closed in the vertical direction in FIG.
0a and the second die 20b, the cavity 32 in cooperation with the pressing surface 30 that presses the outer surface of the pipe 12 'and the inner die 18.
(FIG. 4) forming cavity 34 and inner mold 1
A joining surface 36 is formed which joins the joining surface 28 of FIG. On the cavity forming surface 34 of the first mold 20a, the hot air outlet 3
8 and a hot air outlet 40 are formed, and inside the first mold 20a, a hot air passage 42 communicating with the hot air outlet 38, a hot air passage 44 communicating with the hot air outlet 40, and a stopper pin 46.
A hole 48 through which the hole is inserted and a hole 52 through which the stopper pin 50 is inserted are formed. Stopper pins 46 and 50
By hydraulic cylinders 54 and 56 respectively.
In the vertical direction, whereby the hot air outlet 38 and the hot air outlet 40 are opened and closed. A hot air generator 57 is connected to the hot air path 42. on the other hand,
The second mold 20b is provided with a sprue 60 for injecting a moldable material 58 (FIG. 5) such as polyethylene or polybutene into the cavity 32 (FIG. 4).

In manufacturing the pipe 10 with a socket (FIG. 1), first, as shown in FIG. 3, the magnetic alloy heater 16 (FIG. 2) is mounted on the heater mounting portion 26 of the inner mold 18, and the pipe is mounted. The pipe 12 'whose tip is preheated to the mounting portion 22
(A straight pipe in this embodiment) is mounted. At this time, the tip portion of the pipe 12 'is slightly expanded in diameter by the tapered portion 24 of the inner mold 18. Then, as shown in FIG.
That is, the first molds 20 a and 20 b are closed to form the cavity 32, and hot air is blown into the cavity 32 from the hot air generator 57 connected to the hot air path 42. At this time, both the hot air outlet 38 and the hot air outlet 40 are open, so that the hot air blown from the hot air outlet 38 to the cavity 32 is exhausted from the hot air outlet 40 through the hot air path 44.

When the tip portion of the pipe 12 'is heated to near the melting point by blowing hot air into the cavity 32, as shown in FIG. 5, the stopper pins 46 and 50 cause the hot air outlet 38 and the hot air outlet 40 to flow. The moldable material 58 is injected into the cavity 32 from an injection molding machine (not shown) connected to the sprue 60. Then, the tip portion of the pipe 12 'and the moldable material 58 are cooled. After cooling, as shown in FIG. 6, the outer mold 20, that is, the first mold 20a and the second mold 20b are opened, and the pipe with a socket 10 is removed from the inner mold 18.

According to this embodiment, due to the thermal expansion of the pipe 12 'heated by hot air, the pipe 12' and the inner mold 18 are
The gap between the outer mold 20 and the outer mold 20 can be reliably sealed. Therefore, the moldable material 58 injected into the cavity 32 can be prevented from leaking. Also, pipe 1
Since the tip portion of 2'is heated to near the melting point, the fusion property between the pipe 12 'and the moldable material 58 (FIG. 5) can be improved, and the tip portion of the pipe 12' can be tapered (see FIG. Coupled with the fact that the diameter is increased in 3), the bondability between the pipe body 12 and the receiving port 14 (FIG. 1) can be improved.

In the above-mentioned embodiment, the reticulated magnetic alloy heater 16 (FIG. 2) is used, but instead of this, a magnetic alloy heater formed as punching metal as shown in FIG. 7, for example. 62 or a magnetic alloy heater 68 in which a magnetic alloy powder 66 is mixed with a synthetic resin 64 as shown in FIG. 8 may be used. Further, in the above-mentioned embodiment, the pipe 12 '(straight pipe) is used, but instead of this, cheese, elbow or the like may be used. In this case, for example, a joint or a pipe with a socket as shown in FIG. 9 or 10 can be obtained.

Further, the present invention is not limited to the pipe 10 having the electric fusion receiving port as in the above-described embodiment, but may be a pipe 72 having an adhesive receiving port 70 as shown in FIG. 11 or as shown in FIG. It can also be applied when manufacturing the pipe 76 having the rubber ring receiving port 74. That is, the pipe 72
When manufacturing (FIG. 11), the step of mounting the magnetic alloy heater on the heater mounting portion 26 (FIG. 3) is omitted, and when manufacturing the pipe 76 (FIG. 12), the rubber ring 78 is mounted. Cavity 3 for forming a groove 80 for
2 (FIG. 4) is deformed.

[Brief description of drawings]

FIG. 1 is an illustrative view showing a pipe with a socket.

FIG. 2 is an illustrative view showing a magnetic alloy heater used in the pipe with a socket of FIG.

FIG. 3 is an illustrative view showing a state in which a magnetic alloy heater and a pipe are attached to an inner mold.

FIG. 4 is an illustrative view showing a state in which an outer mold is closed to form a cavity.

FIG. 5 is an illustrative view showing a state where a moldable material is injected into a cavity.

FIG. 6 is an illustrative view showing a state where an outer mold is opened.

FIG. 7 is an illustrative view showing a modified example of a magnetic alloy heater.

FIG. 8 is an illustrative view showing a modified example of the magnetic alloy heater.

FIG. 9 is an illustrative view showing a state where cheese is used as a pipe.

FIG. 10 is an illustrative view showing a state where an elbow is used as a pipe.

FIG. 11 is an illustrative view showing another pipe with a receptacle to which the present invention is applied.

FIG. 12 is an illustrative view showing another pipe with a receptacle to which the present invention is applied.

[Explanation of symbols]

 10, 72, 76 ... Pipe with socket 12 ... Pipe body 12 '... Pipe 14, 70, 74 ... Socket 16, 62, 68 ... Magnetic alloy heater 18 ... Inner mold 20 ... Outer mold 32 ... Cavity 38 ... Hot air blowing Outlet 40 ... Hot air discharge port 42,44 ... Hot air path 46,50 ... Stopper pin 54,56 ... Hydraulic cylinder 57 ... Hot air generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taku Taku 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Vinyl Pipe Factory Co., Ltd.

Claims (2)

[Claims] 1. A pipe is attached to an inner die, (b) An outer die is joined to the inner die to form a cavity, and (c) Hot air is blown into the cavity to end the pipe. Is heated to near the melting point, (d) the path of the hot air is closed, (e) the moldable material melted in the cavity is injected to form a socket at the end of the pipe, with a socket Pipe manufacturing method. 2. A pipe with a socket according to claim 1, wherein a magnetic alloy heater is attached to the inner mold before the step (a) to form an electro-fusion socket containing the magnetic alloy heater. Method.