JPH06339953A - Stamper installing device for injection molding machine for disk - Google Patents

Abstract

PURPOSE:To form a disk without generating flow marks and the like, replace a stamper simply and retain the same securely. CONSTITUTION:A step section 18 being in contact with the inner peripheral edge of a stamper 15 is formed on the front end face of a stamper holder 13. The step section 18 is protruded toward a fixed mold 1 by the thickness (h) almost same as the thickness (s) of the stamper 15, and the peripheral end face of the step section 18 is continued in the plane shape to a mirror face 16 of the mold. The stamper holder 13 is set on the center of the mirror face 16, and a passage 20 communicating with the neighborhood of the inner peripheral edge of the stamper 15 of the mirror face 16 is formed, and a suction device is communicated with the passage 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper mounting device used in a mold of a disk injection molding machine for molding a disk for recording media such as a video disk and an audio disk (hereinafter referred to as a disk). .

[0002]

2. Description of the Related Art As shown in FIG. 3, a mold of an injection molding machine for manufacturing a conventional disk comprises a fixed mold 1 and a movable mold 2, and a cavity 3 is formed on the abutting surface of both. To be done. Then, a sprue bush 5 is attached to the center of the fixed mold 1, a perforated disk-shaped stamper 15 is located on the mirror surface portion 16 facing the cavity 3 of the movable mold 2, and the inner peripheral surface of the stamper 15 is a stamper. It was held by the collar portion 36 of the holder 35.

When a disk is formed by the injection molding machine thus constructed, the molten resin is injected from the sprue bush 5 provided in the center of the fixed mold 1 to the center of the mold cavity 3 and injected. The molten resin diffuses radially and is filled in the mold cavity 3. On the other hand, the air generated in the mold cavity and the gas generated from the molten resin (hereinafter simply referred to as gas) is moved in the outer peripheral direction of the mold cavity by the diffusion of the molten resin and flows out of the mold cavity 3.

[0004]

However, in the above-mentioned conventional technique, in order to hold the stamper 15 at the center of the movable mold 2, the outer peripheral surface of the flange portion 36 of the stamper holder 35 is
Since it bulges to the fixed mold side and forms a step, when the molten resin is injected, it becomes a blind spot (edge) of the flow path and the molten resin is not sufficiently diffused, and gas, air, etc. are in this blind spot. It remains and is not pushed out smoothly toward the outer circumference of the cavity. When pressure is applied to the cavity by the injection holding pressure, which is the final stage of injection filling, the gas G cannot be escaped to the outside of the cavity because it is surrounded by the molten resin filled in, as shown in FIG. In addition, a triangular flow mark F is generated at a position close to the outer peripheral side surface of the stamper retainer, and when the flow mark F reaches the lead-in R of the disc D, information cannot be input and the disc D is a defective product. There was a problem that became. Further, as shown in FIG. 5, the gas G that cannot escape escapes from the gap 37 between the flange portion 36 of the stamper holder 35 and the stamper 15 into the space between the stamper 15 and the mirror surface 16 and is solidified, thereby extending the life of the stamper. It was the cause of shortening. Also, in order to eliminate the occurrence of this flow mark, it is conceivable to slow down the injection speed, but if the injection speed slows down, the birefringence of the molded disk will deteriorate and the filling time will take longer, so the working time will be longer. There was a problem.

Further, in the above-mentioned prior art, even if dust enters the space for inserting the stamper holder when the stamper holder is removed from the movable die for replacing the stamper, the space can be cleaned because the space is narrow. There was also the problem that dust entered between the stamper and the mirror surface. Furthermore, since the inner diameter of the stamper varies depending on the manufacturer, the stamper and the stamper holder do not correspond to each other, and the die itself may have to be replaced when the stamper is replaced.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to form a disk having a good birefringence without generating flow marks or the like. Therefore, it is an object of the present invention to provide a stamper mounting device that can be easily replaced in correspondence with stampers having various inner diameters without replacing the mold itself.

[0007]

In order to achieve the above object, a stamper mounting device of an injection molding machine for a disk according to the present invention has a stepped portion which is in contact with an inner peripheral edge of the stamper on a front end surface of a stamper holder. The step portion projects toward the fixed mold with a thickness substantially the same as the thickness of the stamper, and a stamper holder in which the peripheral end surface of the step portion is planarly continuous with the mirror surface of the mold is provided at the center of the mirror surface. A passage communicating with the inner peripheral edge of the stamper on the mirror surface is provided, and a suction device is communicated with the passage.

[0008]

Since the present invention is configured as described above, when the suction device is driven by fitting the inner peripheral edge of the stamper to the step portion of the stamper holder, the air between the stamper and the mirror surface passes through the passage. The stamper is ejected and adsorbed and held in close contact with the mirror surface, and the stamper holder is formed so that the stepped portion has approximately the same thickness as that of the stamper.The stamper holder forms a smooth continuous surface with the tip surface and the stamper. To do. The molten resin injected into the cavity is diffused with good fluidity along a smooth continuous surface so that the gas does not remain around the stamper holder, and therefore flow marks do not occur on the molded disk. When the driving of the suction device is stopped, the suction holding of the stamper on the mirror surface is stopped and the stamper can be easily replaced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the center of the mold, in which a fixed mold 1 and a movable mold 2 are clamped to form a disk-shaped cavity 3.

The fixed mold 1 is a fixed platen (not shown).
, And a sprue bush 5 for injecting molten resin is provided at the center.

The movable mold 2 is a movable plate (not shown).
It is attached to the fixed mold 1 and is movable back and forth with respect to the fixed mold 1. At the center of the movable mold 2, a center pin 11 and a punch 12 are slidably provided inside a sleeve 10, and a stamper holder 13 and an inner bush 14 are inserted on the outer periphery of the sleeve 10.

The movable mold 2 thus constructed is
As shown in FIG. 2, on the front end surface of the stamper holder 13, a stepped portion 18 having a diameter of several μm with respect to the inner diameter of the stamper 15 has a thickness substantially the same as the thickness s of the stamper 15 toward the fixed mold 1. The end face around the step portion 18 of the stamper holder 13 and the inner bush 14 are continuous with the mirror surface 16 to form an annular flat surface.

An annular groove 21 is formed on the outer peripheral surface of the inner bush 14.
A small gap 22 for sucking the stamper 15 is provided between the inner bush 14 and the movable die 2 from the annular groove 21 to the mirror surface 16.
It is connected to a suction device (not shown) via 20.

The stamper 15 has its inner peripheral edge fitted to the step portion 18 of the stamper holder 13 and is sucked from the gap 22 through the annular groove 21 and the passage 20 by driving the suction device, so that the movable mold 2 It is adsorbed and held on the mirror surface 16 of. The outer peripheral portion of the stamper 15 is covered and held by an outer peripheral ring (not shown).

An annular groove 30 is provided near the front end of the sleeve 10, and an annular groove 31 is provided near the rear front end. In the case of the present embodiment, two passages 32 are provided between the annular groove 30 and the annular groove 31 to connect them, and the annular groove 31 has an air compressor (not shown) via the passage 33. ) Is connected to. Further, a gap 34 is formed between the outer peripheral surface of the sleeve 10 and the inner peripheral surface of the stamper holder 13 from the annular groove 30 to the front end. This gap 34 is open to the cavity 3 over the entire circumference between the sleeve 10 and the stamper holder 13, and is a minute amount that allows passage of gas but does not pass molten resin. When the completed and mold-opened disk is taken out, the compressed air of the air compressor is jetted from the gap 34 through the passage 33, the annular groove 31, the passage 32 and the annular groove 30 to improve the mold release of the disk.

[0016]

The present invention has the effects as described below by being configured as described in detail above.

Since the stamper holder does not have a collar portion for pressing the stamper, it is arranged in the same plane as the stamper and does not project into the cavity. Therefore, the fluidity of the molten resin is improved and the gas remains. There is nothing to do. Therefore, the molded disk does not have a flow mark defect. Further, since it is not necessary to slow down the filling rate of the molten resin, the molding time can be shortened and the birefringence of the disc can be improved.

Since the stamper has its inner diameter fitted to the step portion of the stamper holder and is sucked and held on the mirror surface,
The stamper can be easily removed by stopping the driving of the suction device. Therefore, the stamper can be easily and surely replaced.

Since the vicinity of the inner peripheral edge of the stamper is adsorbed and held on the mirror surface, gas does not enter between the mirror surface and the stamper and solidify, so that the service life of the stamper can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold according to the present invention.

FIG. 2 is a partially enlarged view of a movable mold.

FIG. 3 is a cross-sectional view of a conventional mold.

FIG. 4 is an explanatory diagram of a defective disk formed by a conventional technique.

FIG. 5 is a partially enlarged view showing an example in which the inner peripheral edge of the stamper is deformed in the conventional mold.

[Explanation of symbols]

 1 Fixed mold 2 Movable mold 3 Cavity 10 Sleeve 13 Stamper 14 Inner bush 15 Stamper 16 Mirror surface 18 Step 20 Passage 21 Annular groove 22 Gap

Claims (1)

[Claims] 1. A stamper holder is provided with a step portion on a front end surface thereof in contact with an inner peripheral edge of the stamper, and the step portion projects toward a fixed mold with a thickness substantially equal to a thickness of the stamper and surrounds the step portion. A stamper holder whose end face is continuous with the mirror surface of the mold in a plane is provided at the center of the mirror surface, a passage communicating with the inner peripheral edge of the stamper on the mirror surface is provided, and a suction device is communicated with the passage. Stamper mounting device for disk injection molding machine.