JPH074835B2 - Information recording disk injection mold - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for injection molding an information recording board such as an optical disk.

[0002]

2. Description of the Related Art In this type of injection mold, a gate cutting punch is provided at the center of the movable mold facing the sprue portion on the fixed mold side, and the mold surface of the cavity is mirror-finished.

Injection molding of an information recording board is carried out by injecting and filling molten resin into a cavity from a sprue, and punching the central portion of the product with a punch for the purpose of gate cutting before the molten resin is completely solidified. Is going.

The injection mold disclosed in Japanese Patent Application Laid-Open No. 2-175122 has a substrate ejector and a gate cut punch in order from the outside in the center of the movable mold facing the sprue bush on the fixed mold side, concentrically with the stamper suppression. And a sprue ejector pin are movably inserted independently of each other.

Further, a split groove in the mold opening / closing direction is provided at the rear part of the gate cut punch, and penetrates the groove to project outward.
The sprue ejector pin is provided with a protrusion that can come into contact with the rear end of the substrate ejector pin, and a substrate ejector pin, a gate cut punch, and a spring for retracting the sprue ejector pin are provided.

[0006]

In such a conventional technique, since the gate cut punch is formed by a thick sleeve, an excessive compression force acts on the central portion of the product during punching, which affects the birefringence. Easy to give.

Further, since a split groove is provided in the rear portion of the gate cut punch and a projection or an engaging portion formed on the rear side surface of the sprue ejector pin is fitted in the split groove, there is a difficulty in processing each member, It also has problems such as high cost.

The present invention has been conceived in order to solve the above-mentioned conventional problems, and its object is to enable punching of a central portion of a product by means of a thin gate cut sleeve,
Another object of the present invention is to provide an information recording disk molding injection mold having a new structure in which each member can be easily processed and the mold cost can be reduced more than ever.

[0009]

According to the features of the present invention according to the above-mentioned object, a guide core having a rear end fixed to a central portion of a movable mold facing a sprue portion on the fixed mold side, and a guide core thereof. A runner protruding pin which is internally mounted in the core so as to be able to move forward and backward and which has an extruding piece having a flange connected to the rear end thereof, and a gate-cut sleeve with a thin front portion slidably fitted around the outer periphery of the guide core, and its gate. The product protruding sleeve slidably fitted on the outer side of the cut sleeve, and the push pin protruding through the fixed portion of the guide core and projecting to the rear end of each sleeve, and the push pin of the gate cut sleeve. Is located in front of the ejector piston together with the extrusion piece, and the extrusion pin of the product protruding sleeve is located in front of the flange of the extrusion piece with a required space.

[0010]

[Operation] In the above configuration, the gate cut sleeve moves forward and backward while being held by the guide core and the product projecting sleeve. For this reason, the lateral deflection of the gate cut sleeve during movement is almost eliminated, and the load is less likely to be biased during punching.

Further, in punching with a thin gate cut sleeve, the compression area for the punched portion of the product is smaller than in the case of thick wall, and it is not necessary to consider the density change due to compression during punching. The deterioration of refraction is prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the figure, 1 is a fixed mold, 2 is a movable mold, and a cavity 3 for molding an information recording board is formed on a parting line of both molds.

A sprue bush 4, a guide bush 5, and a cylindrical stamper retainer (inner circumference) 6 are concentrically stacked from the inside in the central portion of the fixed mold 1.

The movable mold 2 is composed of a front mold 2a and a rear mold 2b which form a cavity 3, and a sleeve 7 is fitted in the center of the front mold 2a facing the cavity 3. is there.

A punching and projecting mechanism, which is constructed by stacking a gate cut sleeve 9 and a product projecting sleeve 10 in order and concentrically around the outer periphery of the guide core 8, is inserted in the sleeve 7.

The guide core 8 is provided with a step portion 8a and has a pin hole 12 formed in the rear part and having an outer diameter larger than the front part in the axial direction, and a peripheral edge of a flange 11 formed at a rear end edge of the guide core 8. It is fixed in the mold by being sandwiched by casing members 13 and 14 which are in the mold and bolted to the front mold 2a.

In the pin hole 12 of the guide core 8,
The runner projecting pin 15 is inserted so as to be able to move forward and backward, and the rear end portion of the runner projecting pin 15 is connected to an extruding piece 17 integrally formed with a flange 16 that fits in the casing member. A return spring 18 is provided between the return spring 18 and the stepped portion 8a.

The gate cut sleeve 9 is slidably fitted on the outer side of the guide core 8, and the front portion is formed to have a smaller diameter and a thinner wall than the rear portion.

The product projecting sleeve 10 slidably fitted in the gate cut sleeve 9 is formed by a stepped sleeve having a front portion thicker than a rear portion,
The flange 19 at the rear end between the step portion 10a and the step portion 9a of the gate cut sleeve 9 and at the rear end of the product projecting sleeve 10.
And the front mold 2a between the return springs 20 and 2 respectively.
1 is provided.

The rear end portion of the gate cut sleeve 9 penetrates the flange 16 of the extruding piece 17, and the extruding piece 17 has an end surface which is located in front of the ejector piston 24 in the movable plate 31. A pin 22 is provided in a protruding manner, and a push-out pin 23 having an end face positioned on the front surface of the flange 16 at a required interval is provided in a rear end portion of the product protruding sleeve 10.

The ejector piston 24 has an ejector rod 25 therein, and the pushing piece 17 is located in front of the ejector rod 25.

Further, a counterbore slightly deeper than the gate cut stroke is formed on the rear end face of the casing member 13, and the rear end of the push-out pin 22 projects therefrom by the gate cut stroke. Therefore, the ejector piston 24
Is restricted by the contact with the casing member 13,
Since the thin gate cut sleeve 9 is not pressed beyond the predetermined stroke, it is not damaged even if the punching is performed by pressing.

The guide core 8 is fixed to the mold by fastening the casing member 14 to the front mold 2a with bolts 26. In this fixing, the positioning pin 27 is attached to the front mold 2a in advance, a cylindrical spacer 28 is interposed between the positioning pin 27 and the mold back surface, and then the casing member 14 is inserted into the positioning pin 27. After that, the bolt 26 is inserted into the casing member 14 and the spacer 28.

Further, the casing member 13 is fitted into the positioning pin 27, and the casing member 14 is covered with the bolt 29.
The casing members are fastened to each other by. Incidentally, 30 is a support pillar of the guide core 8 and 32 is a stamper retainer (outer periphery).

In the above structure, as the ejector piston 24 advances, the gate cut sleeve 9 is pushed out to the sprue bush 4 via the push pin 22 to cut the gate at the center of the product into a circular shape.

After the gate cutting, the movable mold 2 is moved backward to open the mold. Further, after the mold is opened, the ejector rod 25 moves forward to press the pushing piece 17. By this pressing, the runner projecting pin 15 advances, and the circular punched portion (not shown) attached to the tip of the runner projecting pin 15 is knocked down.

When the ejector rod 25 further advances, the extrusion pin 23 of the product projecting sleeve 10 is pressed by the flange 16 of the extruding piece 17, so that the product projecting sleeve 10 also advances and the central portion is punched out in a circular shape. A disk-shaped molded product (not shown) is released from the movable mold.

In the above-mentioned embodiment, the punching is performed by pressing, but the sprue bush 4 and the gate cut sleeve 9 have substantially the same diameter, and the sprue bush 4 is slightly retracted from the guide bush 5 to form a recess. The tip of the gate cut sleeve 9 can be inserted into the recess for punching, and the sprue bush 4 and the gate cut sleeve 9 can have substantially the same diameter, and the sprue bush 4 can be movably provided. It is also possible to move the bush 4 and the gate cut sleeve 9 relative to each other and perform gate cutting by shearing to punch.

[0029]

As described above, according to the present invention, the guide core 8 fixed to the central portion of the movable mold 2 facing the sprue portion on the fixed mold side and the guide core in which the extruding piece 17 is connected to the rear end are provided. A runner projecting pin 15, a thin gate cut sleeve 9 slidably fitted around the outer periphery of the guide core 8, a molded product projecting sleeve 10 slidably fitted outside the gate cut sleeve 9, and The push pin 22 at the rear end of the gate cut sleeve 9 located on the front face of the ejector piston 24 together with the push piece 17, and the flange 1 of the push piece 17
6 is composed of the push-out pin 23 at the rear end of the product projecting sleeve 10 which is located on the front surface of the product projecting member 6 with a required space, so that the gate cut sleeve is moved forward and backward while being held by the guide core and the product projecting sleeve. As a result, there is almost no lateral runout of the gate cut sleeve during movement, so that there is little bias in the load during punching, and even if the gate cut sleeve is thin, it can withstand long-term use.

Further, in punching with a thin gate-cut sleeve, the compression area for the punched portion of the product is smaller than in the case of thick wall, so it is not necessary to consider the change in density due to the compression during punching, and it is possible to obtain multiple The refraction does not deteriorate.

Furthermore, a gate cut sleeve and a product projecting sleeve are fitted concentrically in order on the outside of a guide core in which the runner projecting pins are installed, and an extruding piece and an extruding pin are provided at the rear ends of these members, Since each member except the guide core can be moved, it is easier to process each member than the conventional one in which the combination of these members is performed by using the fitting of the cut groove and the protrusion. It has the feature that high-precision molds can be manufactured at low cost using general-purpose machine tools such as lathes and drilling machines.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an information recording disk molding injection mold according to the present invention in a mold closed state.

FIG. 2 is a vertical cross-sectional view of a main part in the same punched state.

FIG. 3 is a vertical cross-sectional view of the main part in the same protruding state.

[Explanation of symbols]

 1 Fixed mold 2 Movable mold 3 Cavity 4 Sprue bush 8 Guide core 8a Step part 9 Gate cut sleeve 9a Step part 10 Product protruding sleeve 11 Flange 12 Pin hole 13 Casing member 14 Casing member 15 Runner protruding pin 16 Flange 17 Extrusion piece 22 Extrusion Pin 23 Extrusion Pin 24 Ejector Piston 25 Ejector Rod

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // B29L 17:00

Claims (1)

[Claims] 1. A guide core having a rear end fixed to a central part of a movable mold facing the sprue part on the fixed mold side, and an extrusion having a flange which is internally and movably mounted in the guide core. A product in which a runner protruding pin connecting a piece to the rear end, a gate cut sleeve with a thin front part slidably fitted around the outer periphery of the guide core, and a slidable fit outside the gate cut sleeve A protruding sleeve and an extruding pin that penetrates through the fixed portion of the guide core and projects from the rear end of each sleeve, and the extruding pin of the gate-cut sleeve is located in front of the ejector piston together with the extruding piece. An injection die for molding an information recording disk, characterized in that the extrusion pin of the product projecting sleeve is located at a required interval on the front surface of the flange of the extrusion piece.