JPH0374610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a molding die used, for example, in molding a ferrule of an optical fiber plastic connector (hereinafter referred to as an optical connector).

[Technical background of the invention and its problems]

As shown in FIG. 3 as an example of a conventional optical connector, a ferrule 5 has a hole 2 into which a cored optical fiber 1 is inserted, a microhole 4 of, for example, 125 μm into which an optical fiber 3 is inserted, and this ferrule. 5
The ferrule 5 is made up of a sleeve 6 provided on the outer periphery of the ferrule 5, and a cap nut 7 that connects the sleeve 6 to the ferrule 5.

The ferrule 5 is composed of a fixed mold 10 and a movable mold 20, as shown in FIG. The fixed mold 10 includes a fixed mold main body 14 having a molding resin injection port 11, a guide hole 12, and a core pin insertion hole 13, and is inserted and fixed into the core pin insertion hole 13 of the fixed mold main body 14, and has a micro pin insertion hole. It consists of a core pin 15 having a hole 16. The movable mold 20 includes a movable mold main body 22 having a hole 21 and a guide pin 24 for setting the outer shape of the ferrule 5, and a cavity insertion piece ( It consists of a micro pin holder) 23 and a micro pin 25 which is set in this cavity insertion piece 23 and can be inserted into the micro pin insertion hole 16 of the core pin 15.

In order to perform molding using a molding die having such a configuration, the fixed die 10 and the movable die 20 are combined as shown in FIG. Molding resin injection port 11
You can inject it into. By doing this, the resin 30 is gradually injected from the upper part to the lower part of the cavity formed by the hole 21 of the movable mold body 22 and the core pin 15, and finally
The resin 30 is injected near 5. This minute pin 2
Since the resin 30 injected near the cylinder 5 remains at the tip of the cylinder for a long time, its deterioration progresses and physical property values such as molecular weight decrease. Moreover, the air inside the cavity and the gas bubbles generated from the resin 30 have no place to escape, and the resin 30 is cooled while being fixed near the micro pin 25, which is the most important part of the final product, the ferrule 5. Variations in the microhole diameter of the tip and the external dimensions of this part,
Furthermore, it also causes roughness of the external surface. Furthermore, a weld line is formed at the tip of the ferrule 5 due to the convergence of the separated resin flows, which causes a decrease in mechanical strength.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and it is possible to reduce variations in the microhole diameter of a molded product and the external dimensions of this part, and to reduce the roughness of the external surface of the tip of the molded product. The purpose of the present invention is to provide a molding die that can prevent a decrease in mechanical strength.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the drawings. Here, a molding die used for molding a ferrule of an optical connector will be described as an example, but the molding die is not limited to this and may be used for molding other products. FIG. 1 is a sectional view showing one embodiment of the molding die of the present invention, which is composed of a fixed mold 40 and a movable mold 50. The fixed mold 40 includes a fixed mold body 44 having an injection port 41 for a molten material for molding, a guide hole 42, and a core pin insertion hole 43;
It consists of a core pin 45.

This core pin 45 is rod-shaped and has a flange 45a formed at one end and an axial recess 45b formed at the other end. The core pin 45 having such a structure is slidably (vertically movable) inserted into the core pin insertion hole 43 of the fixed mold body 44 and supported by the flange 45b.

The movable mold 50 has a guide pin 51 at the upper end, a movable mold main body 53 having a through hole 52 in the center for setting the outer shape of the product, and a movable mold main body 53 having a through hole 52 in the center thereof. A cavity insertion piece (micro pin holder) 54 provided at the bottom and a micro pin 55 supported by this cavity insertion piece 54.
It is made up of.

Fixed mold 40 and movable mold 5 configured in this way
0 are assembled as shown in FIG. 1, this is set in a molding machine, and the molten material 60 for molding is injected into the injection port 41 from this cylinder. Then, the molten material for molding 6
0 first flows through the cavity formed by the through hole 52 and the core pin 45 and reaches the bottom of the cavity. The molten material 60 for molding that has reached the bottom of the cavity has no place to escape, passes through the gap between the bottom of the cavity and the tip of the core pin 45, enters the inside of the recess 45b of the core pin 45, and finally enters the bottom of the recess 45b.

In this case, the molten molding material 60 that has entered the cavity 45b, especially the bottom, has remained inside the cylinder for a long time, so it has progressed to deteriorate and its physical properties such as molecular weight have decreased. In the part where the pin 55 protrudes, that is, the part that becomes the tip of the ferrule 5, the molten material 60 for molding is less likely to deteriorate and its physical properties such as molecular weight are less likely to decrease. Therefore, the product i.e. ferrule 5
The variation in the microhole diameter at the tip of the ferrule 5 and the variation in the external dimensions of this portion are reduced, and the roughness of the external surface of the tip of the ferrule 5 is also reduced. Further, since a weld line formed by the merging of the molding melt material 60 injected from the injection port 41 is not formed at the tip of the ferrule 5, a decrease in mechanical strength can be prevented.

In the state shown in FIG. 1, by further injecting the molten material 60 for molding from the cylinder into the injection port 41, the molten material 60 flows through the cavity in the same manner as described above, and enters the depression 45b of the core pin 45 from the bottom of the cavity. molten material for molding 60
There is no place to escape, and the pressure of the molten molding material 60 pushes the core pin 45 upward, as shown in FIG. 2, and this operation is performed continuously.

As the core pin 45 is pushed upward by the pressure of the molten material 60, at the final point, the molten material 60 that has remained inside the cylinder for a long time becomes a problem in products such as ferrules. Flows further away from the bottom of the cavity (the protruding part of the micro pin 55), which further reduces the variation in the micro hole diameter of the product and the variation in the external dimensions of this part, and further reduces the roughness of the external surface at the tip of the product. Even less.

In the embodiment described above, the injection port 41 for the molten material 60 for molding of the fixed mold 40 is connected to the movable mold main body 53.
The parts that are not formed in the mold body 44 but are formed in the mold body 44 are parts that do not require high dimensional accuracy (specifically, the flange part) of a product that can be formed within the cavity, such as the ferrule 5, so the product is not formed in the molding mold. This is to facilitate processing after taking it out.

〔Effect of the invention〕

According to the present invention described above, it is possible to reduce variations in the microhole diameter of the molding die and the external dimensions of this part, and to reduce the roughness of the external surface of the tip of the molded product. It is possible to provide a molding die that can prevent a decrease in mechanical strength.

[Brief explanation of drawings]

1 and 2 are both cross-sectional views of an embodiment of a molding die according to the present invention, with FIG. 1 showing a state in the initial stage of molding, and FIG. 2 showing a state in the middle of molding. , FIG. 3 is a sectional view showing a schematic configuration of an optical connector, and FIGS. 4 and 5 are sectional views showing an example of a conventional molding die for manufacturing the ferrule shown in FIG. The figure shows the state before molding, and FIG. 5 shows the state after molding. 40...Fixed mold, 41...Injection port, 42...
Guide hole, 43... Core pin insertion hole, 44... Fixed mold body, 45... Core pin, 45a... Flange, 45b... Hollow, 50... Movable mold, 5
1...Guide pin, 52...Through hole, 53...Movable mold body, 54...Cavity insertion piece (micro pin holder), 55...Minute pin.

Claims (1)

[Scope of Claims] 1. A fixed mold in which an injection port for a molten material for molding is formed in a fixed mold body, and a core pin for setting the inner shape of a product in the fixed mold body, and this fixed mold. In a molding mold consisting of a movable mold in which the core pin is inserted into a movable mold main body in a state in which the core pin is assembled in a mold, and a hole is formed for setting the outer shape of the product, a recess is formed in the end surface of the core pin. A molding mold having a recess formed in the recess, in which the molten material for molding from the injection port of the fixed mold flows from around the recess in the final stage of molding. 2 A fixed mold in which an injection port for the molten material for molding is formed in the fixed mold body, and a core pin for setting the inner shape of the product is provided in the fixed mold body, and the fixed mold is combined with this fixed mold. In a molding mold consisting of a movable mold body into which the core pin is inserted and a movable mold in which a hole is formed for setting the outer shape of the product, a recess is formed in the end face of the core pin, and the core pin is inserted into the movable mold body. A molding die in which a core pin is slidably provided in the stationary mold body, and the core pin is sequentially slid upward by the pressure of the molten material for molding that flows into the recess from the periphery during molding.