JPH09141668A - Mold for electric fusion bonded joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily mount a heater and to prevent the deformation of the heater at the time of molding. SOLUTION: A heater 20 is mounted at the peripheral side of a mold in the state that two molds are separated from one another. the ends of the molds are butted, and hence a movable piece 30 is externally displaced. Then, the substantial peripheral length of the mold is increased larger than the inner peripheral length of the heater 20, the heater 20 is brought into close contact with the peripheral side of the mold and fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for an electric fusion joint, and more particularly to a molding die for an electric fusion joint for molding an electric fusion joint having a heating element embedded therein.

[0002]

2. Description of the Related Art When molding an electric fusion joint as disclosed in Japanese Patent Application No. 2-86847, after mounting a heating element on the peripheral side surface of the mold, the outer mold is closed. A synthetic resin such as polyethylene is injected into the cavity formed by the mold and the outer mold.

[0003]

In the prior art, it was necessary to set the outer diameter of the mold smaller than the inner diameter of the heat generating element so that the heat generating element could be easily attached to the peripheral side surface of the mold. There was a gap between the peripheral side surface of the mold and the heating element.
Therefore, there is a problem that the heating element cannot be fixed in close contact with the peripheral side surface of the mold and the heating element is undesirably deformed by the flow of the injected synthetic resin.

Therefore, a main object of the present invention is to provide a molding die for an electric fusion joint in which a heating element can be easily mounted and the heating element is not deformed during molding.

[0005]

SUMMARY OF THE INVENTION The present invention is a molding die for an electric fusion joint in which a heating element is mounted on a peripheral side surface in order to form an electric fusion joint in which a heating element is embedded. A fixed piece that defines, a movable piece that forms a gap on the peripheral side surface at the first position and defines the peripheral side surface together with the fixed piece at the second position, and a displacement mechanism for displacing the movable piece to the first position or the second position. Is a molding die for an electric fusion joint.

[0006]

When the movable piece is displaced to the first position by the displacement mechanism, a gap is formed on the peripheral side surface of the mold, and the outer peripheral length of the mold is substantially reduced. Therefore, the heating element can be easily attached to the peripheral side surface of the mold. When the movable member is displaced to the second position by the displacement mechanism after mounting the heating element on the peripheral side surface of the mold, the gap on the peripheral side surface of the mold is closed and the outer peripheral length of the mold is substantially extended. A heating element is closely attached and fixed to the peripheral side surface of the mold.

[0007]

According to the present invention, the heating element can be easily attached. Further, at the time of molding, since the heating element can be closely attached and fixed to the peripheral side surface of the mold, it is possible to prevent the heating element from being deformed. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A molding die 10 for an electric fusion joint of this embodiment shown in FIG. 1 cooperates with an outer die 12 to form a cavity 62 for molding a joint 14 as shown in FIG. The first mold 10a and the second mold 10b are included.
Here, the joint 14 (FIG. 4) includes a substantially hollow cylindrical joint body 16 made of a polyolefin resin such as polyethylene. Receptacles 18a and 18b for receiving a pipe are formed on the inner peripheral portion of the joint body 16, and the fusion zones of the respective receptacles 18a and 18b are made of a magnetic alloy wire as shown in FIG. The heating element 20 is arranged.

As shown in FIGS. 1 to 3, the first mold 10a includes a support member 26 attached to a block 24 attached to the tip of the hydraulic cylinder 22, a fixing piece 28 attached to the tip of the support member 26, and A movable piece 30 and the like attached to the outer peripheral surface of the fixed piece 28 are included. Support member 26
Includes a substantially cylindrical main body 32, and a substantially flange-shaped fixing portion 34 fixed to the block 24 is formed at a rear end portion (left end portion in FIG. 2) of the main body 32. Also, body 3
The fixing piece 28 is attached to the tip end surface of the second member (the right end surface in FIG. 2).
A hole 40 for accommodating one end of the screw hole 36 and the coil spring 38 is formed.

The fixed piece 28 includes a substantially columnar main body 42 having an outer diameter slightly larger than the inner diameter of the heating element 20, and an accommodating portion 44 for accommodating the movable piece 30 is provided on the outer surface of the main body 42. Is formed so as to extend in the axial direction. The bottom surface of the accommodating portion 44 is inclined so as to approach the axis A toward the tip of the main body 42, and the bottom surface of the housing portion 44 has a substantially dovetail-shaped cross section (FIG. 3).
Is formed so as to extend in the longitudinal direction (axial direction of the main body 42). Further, a fitting protrusion 48 having a substantially columnar shape is formed on the tip surface of the main body 42.

The movable piece 30 has the same length as that of the fixed piece 28 and includes a main body 50 which is housed in a housing portion 44 formed in the fixed piece 28. The outer surface of the main body 50 is curved with a predetermined curvature so as to define the peripheral side surface of the first mold 10a together with the outer surface of the fixed piece 28, and the bottom surface of the main body 50 is formed by the accommodating portion 44.
Is inclined along the bottom surface of the. Then, on the bottom surface of the main body 50, a convex strip 52 having a substantially dovetail-shaped cross section that is slidably fitted in the fitting groove 46 is formed. Further, a hole 54 for accommodating the other end of the coil spring 38 is formed in the rear end surface (the left end surface in FIG. 2) of the main body 50.

Then, one end of the coil spring 38 is provided with a hole 40 while the fitting groove 46 and the ridge 52 are fitted to each other and a gap 56 having a predetermined interval is secured between the support member 26 and the movable piece 30.
Is fixed to the inner part of the hole 54 and the other end is fixed to the inner part of the hole 54.
In this state, since the gap 56 is secured between the support member 26 and the movable piece 30, a gap 58 (FIG. 3, FIG. 3, FIG. 3) is formed on the peripheral side surface of the first mold 10a where the movable piece 30 is mounted. 6) is formed. When the coil spring 38 is compressed by pushing the tip of the movable piece 30 and the rear end surface of the movable piece 30 is brought into contact with the support member 26, the movable piece 30 is moved outward to close the gap 58. (Fig. 7).

In the second mold 10b, a fitting concave portion 60 for fitting with the fitting convex portion 48 formed in the first mold 10a is formed at the tip of the fixing piece 28, and the other portion is the first mold. It is formed similarly to the mold 10a. The outer die 12 cooperates with the die 10 to form the cavity 62,
A gate (not shown) for taking in a molten resin from an injection molding machine (not shown) is formed at a predetermined portion of the outer die 12.

When forming the joint 14 (FIG. 4) using such a mold 10 and the outer mold 12, etc., first, the outer mold 12 is opened, and the first mold 10a and the second mold 10a. The heating elements 20 are mounted on the outer surfaces of the first mold 10a and the second mold 10b, respectively, with the hydraulic cylinders 22 separating the respective 10b. At this time, the coil spring 3
Since the movable piece 30 is urged toward the tip of the fixed piece 28 by 8, the first die 10a and the second die 10b.
As shown in FIG. 6, a void 58 is formed on each of the peripheral side surfaces of the heating element 20, and the substantial circumferential length is shorter than the inner circumferential length of the heating element 20. Therefore, the heating element 20 can be easily mounted by deforming the heating element 20 in a slightly elliptical shape.

After mounting the heating element 20, the first die 10a and the second die 10b are moved axially forward by the hydraulic cylinder 22, and the tip surfaces of the two die abut against each other as shown in FIG. . Then, the fitting convex portion 48 formed on the first mold 10a is fitted into the fitting concave portion 60 formed at the tip of the second mold 10b, and the axes A of both are positioned on the same straight line. It In this way, when the front end surfaces are abutted against each other, the movable pieces 30 are slid against the bias of the coil spring 38, and the rear end surfaces of the movable pieces 30 are supported by the support member 26.
Abut on the tip surface of the. In this process, each movable piece 3
Since 0 is moved outward and the gap 58 (FIG. 6) is closed, the substantial perimeter of each of the first die 10a and the second die 10b is slightly larger than the inner perimeter of the heating element 20. Become. Therefore, the first mold 10a and the second mold 10b
The heating element 20 is closely attached and fixed to each of the peripheral side surfaces of the.

After that, the outer mold 12 is closed to close the cavity 6
2 (FIG. 1) is formed, and a polyolefin resin such as polyethylene or polypropylene is injected into the cavity 62. When the resin injected into the cavity 62 is cured, the outer die 12 is opened, and the hydraulic cylinder 22 is used to open the first die 1
0a and the second mold 10b are separated from each other, and the joint 14
Take out.

According to this embodiment, the heating element 20 can be easily mounted on each of the first mold 10a and the second mold 10b, and at the time of molding, each of the first mold 10a and the second mold 10b. Since the heating element 20 is adhered and fixed to the outer surface of the heating element 20, the heating element 20 is not deformed by the flow of the synthetic resin injected into the cavity 62. In the embodiment described above, the movable piece 30 is different from the fixed piece 28.
The circumferential lengths of the first die 10a and the second die 10b are changed by sliding the die in the axial direction. For example, the die 7 as shown in FIGS.
By using 0, the movable piece 30 may be slid only in the radial direction of the fixed piece 28 to change the circumferential length.

In this mold 70, the axial center A is formed as the bottom surfaces of the accommodating portion 44 and the movable piece 30 move toward the tips.
The taper core 72 that is inclined away from the movable piece 30 has a length between the two movable pieces 30 that is substantially the same as the length of each of the movable piece 30 and the fixed piece 28 and that has an outer surface that extends along the bottom surface of the movable piece 30. Are placed. In addition, the movable piece 30
A convex strip 74 having a substantially dovetail-shaped cross section is formed on the rear end surface, and the convex strip 74 is slidably fitted in a fitting groove 76 having a substantially dovetail-shaped cross section formed in the support member 26. Further, a coil spring 80 is arranged between the support member 26 and the taper core 72, with a gap 78 having a predetermined space provided therebetween. Therefore, the tip of the tapered core 72 is fixed to the fixed piece 28.
And it will be slightly projected from the tip of the movable piece 30.

Also in this mold 70, the peripheral length of the mold 70 is changed by sliding the movable piece 30 in the radial direction with respect to the fixed piece 28. 20 (FIG. 5) can be easily mounted, and the heating element 20 can be fixed in close contact with the peripheral side surface of the mold 70 in a state where the peripheral length is increased. As shown in FIG. 13, a molding die 80 for an electric fusion splicing joint of another embodiment shown in FIGS. 11 and 12 is formed by secondary processing a receptacle 84 having a heating element 20 at an end of a pipe 82. The fixing piece 86,
The movable piece 88 and the tapered core 90 are included. Fixed piece 86
Has a first outer diameter that is approximately the same size as the inner diameter of the tube 82.
The portion 92, the second portion 94 having an outer diameter approximately the same as the inner diameter of the receiving opening 84, the taper portion 96 provided between the first portion 92 and the second portion 94, and the tip end surface of the receiving opening 84 are in contact with each other. An accommodating portion 100 is provided in the central portion of the fixed piece 86 including the step portion 98. Then, the two movable pieces 88 are accommodated in the accommodating portion 100, and the tapered core 90 is disposed between the two movable pieces 88. The bottom surface of the movable piece 88 and the outer surface of the taper core 90 are inclined so as to move away from the axis A toward the front, and a cylinder rod 102 of a hydraulic cylinder (not shown) is connected to the rear end of the taper core 90. Therefore, when the taper core 90 is moved in the axial direction by the cylinder rod 102, the movable piece 88 moves to the fixed piece 8.
6 is displaced in the radial direction, whereby the circumferential length of the mold 80 is changed.

When the receiving port 84 is secondarily processed at the end of the pipe 82 by using the mold 80, first, the core pin 90 is moved forward by a hydraulic cylinder (cylinder rod 102) (not shown) to move the movable piece. 88 is displaced inwardly to form a gap 104 on the peripheral side surface of the mold 80 to shorten the substantial peripheral length. Then, the heating element 20 (FIG. 5) is attached to the outer surface of the second portion 94, and the taper core 9 is attached by a hydraulic cylinder (not shown).
By moving 0 backward, the movable piece 88 is displaced outward. Then, the void 1 formed on the peripheral side surface of the mold 80.
04 is closed by the movable piece 88, the substantial perimeter becomes slightly larger than the inner perimeter of the heating element 12, and the heating element 20 is fixed in close contact with the peripheral side surface of the mold 80.

Thereafter, the heat-softened tube 82 is attached to the mold 80.
Of the first portion 92, the tapered portion 96, and the second portion 94 of the pipe 82 is forcibly covered, and the tip of the pipe 82 is stepped on the step portion 9.
8 Then, by closing an outer mold (not shown), the outer surface of the receiving port 84 is defined and the receiving port 84 is cooled. After curing the receiving port 84, the outer mold is opened and the pipe 82 (receiving port 84) is removed from the mold 80.

Also in this embodiment, the heating element 20 can be easily mounted on the peripheral side surface of the mold 80. Further, since the heating element 20 is closely attached and fixed to the peripheral side surface of the mold 80, the pipe 82
The position of the heating element 20 does not shift when the cover is covered.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is an illustrative view showing a first mold.

FIG. 3 is a side view of a first mold.

FIG. 4 is an illustrative view showing a joint.

FIG. 5 is an illustrative view showing a heating element.

FIG. 6 is an illustrative view showing a state in which a heating element is attached to a mold.

FIG. 7 is an illustrative view showing a state in which a movable piece is displaced outward.

FIG. 8 is an illustrative view showing a modified example of the mold.

9 is a side view of the FIG. 8 embodiment. FIG.

FIG. 10 is a plan view of the embodiment shown in FIG.

FIG. 11 is an illustrative view showing another embodiment of the present invention;

12 is a side view of the FIG. 11 embodiment. FIG.

FIG. 13 is an illustrative view showing a joint formed in the example in FIG. 11;

[Explanation of symbols]

 10, 80 ... Mold for forming electric fusion joint 12 ... Outer mold 14 ... Joint 20 ... Heating element 22 ... Hydraulic cylinder 28 ... Fixed piece 30 ... Movable piece 38 ... Coil spring

Claims (2)

[Claims] 1. A molding die for an electric fusion joint, in which the heating element is mounted on a peripheral side surface to form an electric fusion joint in which a heating element is embedded, the fixing piece defining the peripheral side surface. A movable piece that forms a gap on the peripheral side surface at one position and defines the peripheral side surface together with the fixed piece at a second position, and a displacement mechanism for displacing the movable piece to the first position or the second position. A mold for forming an electric fusion joint, comprising: 2. The molding die for an electric fusion joint according to claim 1, wherein an outer peripheral length when the movable piece is in the second position is set to be equal to or longer than an inner peripheral length of the heating element.