JP3732973B2 - Mold for electric fusion joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold for an electric fusion joint in which a heating wire is embedded in the inner peripheral surface of the joint, and more specifically, the terminal pin fixed to the end of the heating wire can be easily set and molded at the time of molding the joint. The present invention relates to a molding die for an electric fusion joint that can be easily taken out later.
[0002]
[Prior art]
Conventionally, many electric fusion joints have been used for connecting synthetic resin pipes such as gas pipes and water / hot water supply pipes. In this electric fusion joint, a heating wire is embedded in the inner peripheral surface of the joint, terminal pins are connected to both ends of the heating wire, and the terminal pins are suspended inside a plug protruding from the outer surface of the joint. It is a thing.
[0003]
In such an electrofusion joint, a heating wire coated with an insulating resin is wound around the outer peripheral surface of a mandrel that forms the inner peripheral surface of the joint, and terminal pins are fixed to both ends of the heating wire. With the terminal holding mold attached, set the mandrel on one of the half-shaped outer molds and fit the terminal holding mold into the locking hole provided in the outer mold, and then close the outer mold Then, a joint is formed by injecting molten resin into the cavity formed between the mandrel and the outer mold, and after the molten resin is cured, the outer mold is opened, and the terminal holding mold and mandrel are removed from the molded product. Manufactured by removing.
[0004]
[Problems to be solved by the invention]
However, in the conventional molding die, when closing the outer die, the terminal holding die fitted with the terminal pin must be fitted into the locking hole of the outer die, which is very troublesome. It was awkward. In particular, when a small-diameter joint is injection-molded, the inner diameter of the outer mold becomes small, so the terminal holding mold cannot be easily fitted into the locking hole of the outer mold, and the molding cycle becomes long. As a result, there is a problem that productivity is remarkably lowered.
[0005]
Therefore, the present invention can easily set the terminal pins, and can easily perform the work of disassembling the molding die and taking out the molded product, thereby shortening the molding cycle and increasing the productivity. An object of the present invention is to provide a molding die for an electric fusion joint.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the mold for an electric fusion joint of the present invention can be divided into a mandrel around which a heating wire is wound and a cavity around which the outer periphery of the mandrel is injected and molten resin is injected. A molding die for an electro-fusion joint having an outer outer die and a block die to which a terminal pin fixed to an end of the heating wire is attached, the positioning projection provided on the block die on the mandrel A positioning groove that engages, and in the positioning groove, a fitting member having a fitting hole into which a lock pin protruding from a block-type positioning projection is fitted is movably accommodated in the mandrel axial direction, A spring for holding the fitting member in a predetermined position is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a molding die for an electric fusion joint according to the present invention. FIG. 1 is a sectional front view showing a state in which a mandrel and a block die are set on an outer die, and FIG. FIG. 3 is an enlarged sectional front view of the main part.
[0008]
The mold for this electric fusion joint includes a mandrel 10, an outer mold 20 disposed on the outer periphery of the mandrel 10, and a block mold 30 set at a predetermined position between the mandrel 10 and the outer mold 20. Have. The mandrel 10 forms the inner peripheral surface of the joint, and when the mandrel 10 is set in a split half outer mold 20 and the outer mold 20 is closed, the mandrel 10 and the outer mold A cavity 21 into which the molten resin P is injected is formed. A recess 22 for holding the block mold 30 is provided on the mating surface of the outer mold 20.
[0009]
A heating wire 11 is wound around a predetermined position on the outer peripheral surface of the mandrel 10, and terminal pins 12 are fixed to both ends of the heating wire 11. A positioning groove 13 for positioning the block mold 30 is provided at the end of the mandrel 10, and a fitting member 14 for holding the block mold 30 is pressed into the positioning groove 13. While being held by the plate 15, the mandrel 10 is housed so as to be movable in the axial direction. Furthermore, a spring 16 for holding the fitting member 14 in a predetermined position is provided between the fitting member 14 and the side wall of the positioning groove 13.
[0010]
The block mold 30 has a support hole 32 for supporting the terminal holding mold 31 to which the terminal pin 12 is mounted, a positioning protrusion 33 protruding in the direction of the mandrel 10 and having a tip engaged with the positioning groove 13, It has a lock pin 34 that protrudes from the distal end surface of the positioning projection 33 and fits into the fitting hole 17 of the fitting member 14. As shown in FIG. 2, the lock pin 34 includes an outer cylinder 35, a pin 36 slidably inserted into the outer cylinder 35, and a spring that urges the pin 36 in a direction protruding from the outer surface of the block mold 30. 37 and a ball 38 that can be projected and retracted from the peripheral wall of the distal end portion of the outer cylinder 35, and a concave portion 39 for accommodating the ball 38 is provided at the distal end portion of the pin 36.
[0011]
In other words, when the outer end of the pin 36 protruding from the outer surface of the block mold 30 is pushed and the pin 36 is pushed into the outer cylinder 35, the ball 38 is accommodated in the recess 39 and can be retracted from the outer periphery of the outer cylinder 35. Thus, the outer cylinder 35 of the ball 38 can pass through the fitting hole 17 of the fitting member 14. On the other hand, when the pin 36 moves in a direction protruding from the outer surface of the block mold 30 by the action of the spring 37, the ball 38 is pushed out from the recess 39 and held in a state protruding from the outer periphery of the outer cylinder 35. Is engaged with the peripheral wall of the fitting hole 17 to be in a retaining state. Therefore, the lock pin 34 is formed so that the fitting state with the fitting member 14 can be released by pushing the pin 36.
[0012]
The procedure for forming the electric fusion joint by using the molding die thus formed is as follows. First, the heating wire 11 is spirally wound around a predetermined position on the outer peripheral surface of the mandrel 10, and then the insulating resin at both ends of the heating wire 11 is peeled off to connect and fix the terminal pins 12. Then, the terminal pin 12 is attached to the terminal holding die 31, the terminal holding die 31 is inserted into the support hole 32 of the block die 30, and the block die 30 is fixed to the mandrel 10.
[0013]
The block mold 30 is fixed to the mandrel 10 by engaging the positioning protrusion 33 with the positioning groove 13 while pushing the pin 36 protruding from the outer surface of the block mold 30, and the end of the lock pin 34 with the fitting member 14. Is fitted into the fitting hole 17. At this time, since the fitting member 14 is held at a predetermined position by the action of the spring 16, by pushing the pin 36 so that the ball 38 can be accommodated in the recess 39, Can be easily fitted into the fitting hole 17. When the pushing force of the pin 36 is released, the pin 36 moves in the projecting direction by the action of the spring 37, so that the ball 38 is pushed out of the recess 39 and protrudes to the outer periphery of the outer cylinder 35, and the tip portion peripheral surface of the pin 36. Thus, the protrusion is held in the fitted state with the fitting member 14. Since the fitting member 14 is held at a predetermined position by the spring 16, the block die 30 can be fixed at a predetermined position of the mandrel 10 by fitting the fitting member 14 and the lock pin 34. it can. After fixing the block mold 30 to the mandrel 10 in this way, the mandrel 10 and the block mold 30 are set in one half-shaped outer mold 20 and the outer mold 20 is closed.
[0014]
Next, the molten resin P is injected into the cavity 21, and the outer mold 20 is opened after the molten resin P filled in the cavity 21 is cured, and the molded product, the mandrel 10 and the block mold 30 are removed. Remove from the mold 20. Next, the block mold 30 is removed from the mandrel 10. At this time, since the molded product taken out from the outer mold 20 is cooled and slightly contracted, the terminal pin 12 moves in the contraction direction of the molded product, and the support hole of the block mold 30 is moved along with the movement of the terminal pin 12. 32 parts move. Therefore, the lock pin 34 also moves with its tip end fitted to the fitting member 14, but the lock pin 34 is fitted because the fitting member 14 is movably accommodated in the positioning groove 13. It moves with the joint member 14.
[0015]
Here, when the fitting member 14 is fixed to the mandrel 10, the lock pin 34 cannot move because the tip is fitted to the fitting member 14, and the outside side is supported. Since it moves with the hole 32 portion, the axis of the lock pin 34 and the axis of the fitting hole 17 are inclined. As described above, when the lock pin 34 is tilted, even if the tilt angle is slight, when the lock pin 34 is pulled out from the fitting hole 17, both contact portions are galling. A large force is required, and an excessive load is applied to the extractor, which greatly affects workability.
[0016]
Therefore, as described above, since the fitting member 14 is formed so as to be movable together with the lock pin 34, the lock pin 34 can be easily extracted from the fitting hole 17 with a light force. The block mold 30 can be easily removed from the.
[0017]
The lock pin 34 is extracted by pressing the pin 36 so that the ball 38 can be accommodated in the recess 39. Then, the fitting member 14 after extracting the lock pin 34 is returned to a predetermined position by the action of the spring 16. In this manner, after removing the block mold 30 from the mandrel 10 and the terminal holding mold 31 from the terminal pin 12, the mandrel 10 is extracted from the molded product, whereby an electric fusion joint having a predetermined shape is obtained.
[0018]
Thus, since the terminal holding die 31 with the terminal pins 12 attached is inserted into the support holes 32 of the block die 30 without fitting into the locking holes of the outer die, the setting of the terminal holding die 31 is facilitated. Further, since the fitting member 14 is movable, the lock pin 34 can be easily removed.
[0019]
In this embodiment, the pipe end cap is exemplified as the electric fusion joint. However, the present invention is also applicable to manufacturing various electric fusion joints such as ordinary socket joints, elbow joints, different diameter joints, cheeses, and saddle joints. can do. Alternatively, the terminal holding mold may be provided integrally with the block mold, and terminal pins may be attached to the terminal holding mold.
[0020]
【The invention's effect】
As described above, according to the present invention, the terminal pin can be easily set and the lock pin can be easily pulled out, so that the molding cycle of the electrofusion joint can be greatly shortened and the productivity can be reduced. Can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional front view showing one embodiment of a molding die for an electric fusion joint.
FIG. 2 is an enlarged cross-sectional front view of the main part of the same.
FIG. 3 is an enlarged cross-sectional side view of the main part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Mandrel, 11 ... Heating wire, 12 ... Terminal pin, 13 ... Positioning groove, 14 ... Fitting member, 15 ... Holding plate, 16 ... Spring, 17 ... Fitting hole, 20 ... Outer metal mold, 21 ... Cavity, 22 ... depression, 30 ... block type, 31 ... terminal holding type, 32 ... support hole, 33 ... positioning projection, 34 ... lock pin, 35 ... outer cylinder, 36 ... pin, 37 ... spring, 38 ... ball, 39 ... recess , P ... Molten resin

Claims (1)

A mandrel around which a heating wire is wound, a separable outer mold that surrounds the outer periphery of the mandrel and forms a cavity through which molten resin is injected, and a terminal pin fixed to the end of the heating wire are mounted. A molding die for an electric fusion joint having a block mold, wherein a positioning groove for engaging a positioning projection provided on the block mold is provided in the mandrel, and the positioning projection of the block mold is provided in the positioning groove. An electric device comprising: a fitting member having a fitting hole into which a lock pin protruding from the fitting member is movably accommodated in a mandrel axial direction; and a spring for holding the fitting member in a predetermined position. Mold for fusion joints.

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