JPH06111388A - Method and mold for forming optical disk substrate - Google Patents

Abstract

PURPOSE:To provide the method and mold for forming the optical disk substrate capable of yielding the good optical substrate which is not affected by the distortion of its outer peripheral part, the shape of flatness and transferability without increasing a post stage, such as trimming. CONSTITUTION:The cavity surfaces 1a, 2a of the mold are formed to the bore larger than the final outside diameter r of the molded substrate 4 for the optical disk. An outer peripheral blanking punch 5 to determine the final outside diameter r is disposed within the mold for forming the molded substrate 4. This outer peripheral blanking punch 5 is so set that its end face is flush with the cavity surface 2a of the mold and thereafter, a raw material 9 for the molded article is packed into the cavity A. The outer peripheral blanking punch 5 is extruded by a punch driving means 6 to determine the outside diameter of the molded substrate 4 during the pressure holding stage after the completion of the packing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an optical disk substrate and a molding die.

[0002]

2. Description of the Related Art There are various conventional methods for producing an optical disk substrate as described below. First, as a first conventional example, there is one disclosed in Japanese Patent Application Laid-Open No. 57-131524, entitled "Method for manufacturing video disc". This is because the mold is formed to be larger than the final outer diameter, the outer peripheral part is provided with a non-recording part, and then the mold is trimmed to obtain a predetermined outer shape. The optical disc is formed so that the influence of the degree or the like does not appear on both sides of the substrate.

A second conventional example is Japanese Patent Laid-Open No. 63-
There is one disclosed in Japanese Patent No. 99932 under the title of "Method for manufacturing optical disk substrate". This is to form a step for pushing up the substrate on the injection nozzle of the mold or the outer peripheral ring, and to move the injection nozzle or the outer peripheral ring in the axial direction relative to the main space when the cured photocurable resin is peeled off. Thus, an optical disk substrate having excellent inner diameter and outer diameter accuracy and thickness accuracy can be easily produced at high speed.

[0004]

In the case of the first conventional example,
Trimming must be done after molding, which is troublesome. Further, in the case of the second conventional example, the molding method is a 2P method using a photocurable resin, and there is a problem that the manufacturing cost is high. Moreover, in this case, since the resin flowing from the injection nozzle provided in the center of the mold is prevented from freely flowing by the outer peripheral ring protruding into the cavity, the occurrence of strain is unavoidable.

In general, when an optical disk is molded by injection molding, the resin raw material filled in the peripheral portion of the disk-shaped cavity is hard to transmit the pressure due to the injection of the raw material, and the resin flow is caused by the outer ring. As a result, the shape defects such as whiskers and residual distortion occur in the outer peripheral portion of the molded substrate, and the transferability of pits and guide grooves for recording information sharply deteriorates in the outer peripheral portion.

[0006]

According to a first aspect of the present invention, the molding is performed in which the inner diameter of the cavity surface of the molding die is formed to be larger than the final outer diameter of the molding substrate for the optical disk. An outer peripheral punch for determining the final outer diameter is arranged in the mold, and after setting the end surface of the outer peripheral punch to coincide with the cavity surface of the molding die, the raw material for the molded body is placed in the cavity. Was filled, and the outer peripheral punching punch was extruded by the punch driving means during the pressure-holding process after the filling was completed to determine the outer diameter of the molded substrate.

According to the second aspect of the invention, in the molding die,
A punch that forms a circular cavity surface having a diameter larger than the final outer diameter of a molded substrate for an optical disc, forms an outer peripheral punch at a position that determines the final outer diameter, and drives and controls the outer peripheral punch. Drive means were provided.

[0008]

According to the first aspect of the present invention, by molding the optical disk substrate, distortion is suppressed even in the outer peripheral portion as compared with the substrate molded by the conventional method, and good transferability of the information recording surface can be maintained. It is possible to obtain a molded substrate having the achieved highly accurate outer diameter dimension without increasing the number of subsequent steps.

According to the second aspect of the present invention, a molding die having an outer peripheral punch is used to fill the molding resin into the cavity, and then the outer peripheral punch located at the outer peripheral portion is operated. As a result, it is possible to manufacture an optical disk substrate with high accuracy and a small amount of eccentricity.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case where the optical disc substrate is produced based on the injection molding method will be described. First,
The overall structure of the molding die will be described. The molds 1 and 2 are arranged on the left and right sides so as to face each other.
The area sandwiched between the two is the space of the cavity A. A sprue 3 is formed in the center of the mold 1 so that a resin (a resin 9 described later) as a raw material for the molded body can be injected. The surface of the mold 1 on the side of the cavity A is a circular cavity surface 1a. The inner diameter of the cavity surface 1a is larger than the final outer diameter r of the molded substrate 4 for an optical disc. Further, at the position that determines the final outer diameter r of the molded substrate 4 within the cavity surface 1a, the outer peripheral punch 5 is provided.
Is provided. The outer peripheral punch 5 is driven and controlled by a punch driving source 6 as a punch driving means, and can be moved so as to project from the inside of the die 1 to the outside. In this case, one end surface of the outer peripheral punch 5 has a shape exposed to the cavity surface 1a, and has a circular narrow width inside the outer periphery of the circular cavity surface 1a. It exists as a surface.

Further, an ejector pin 7 for removing the outer peripheral portion when the molding die 4 is formed is provided in the outer peripheral area of the cavity surface 2a of the die 2. Further, the cavity surfaces 1a and 2 of the molds 1 and 2 which face each other.
A protrusion 8 for preventing the resin 9 from flowing out at the time of molding is circumferentially formed in the outer peripheral region of a.

A method of forming an optical disk substrate by the injection molding method in such a structure will be described. First, in FIG. 2A, both molds 1 and 2 are brought close to each other and clamped to form a space of the cavity A. On the other hand, the outer peripheral punch 5 is left undriven, and the resin 9 as the raw material for the molded body is injected from the sprue 3. In this case, the injection pressure of the resin 9 is set to be larger than the final outer diameter dimension, and the projection 8 on the outer peripheral portion of the cavity surface 1a is set.
Set the pressure so that it can be filled up to the vicinity.

Next, as shown in FIG. 2 (b), during the pressure-holding step in which the resin 9 is still in a fluid state after the filling step, for example, by the punch drive source 6 utilizing hydraulic pressure, The punch 5 is advanced to the opposing cavity surface 2a so that it can be divided into a region of the molded substrate 4 for the optical disk and a region of the annular portion outside thereof. In this way, the pressure holding process is completed. It is possible to produce the molded substrate 4 which is not affected by the distortion of the outer peripheral portion and which is excellent in transferring the information recording surface to the outer peripheral portion and has excellent outer diameter dimensional accuracy.

Then, after the resin 9 has cooled and solidified, the molds 1 and 2 are released, and the formed molded substrate 4 is taken out by using a robot or the like, and at the same time, the ring-shaped body remaining on the outer peripheral portion (outer peripheral ring) is removed. ) 10 is removed by protruding the ejector pin 7.

As described above, the molded substrate 4 can be molded only on the portion of the resin 9 that has flowed in the outer peripheral punch 5 without being affected by physical obstacles such as the outer peripheral ring 10, and is thus formed. The molded substrate 4 according to the present invention is not affected by the distortion even in the outer peripheral portion thereof, and the information recording surface can be excellently transferred to the outer peripheral portion. And in this case,
Since the molded substrate 4 is accurately cut out by the outer peripheral punch 5, the accuracy of the outer diameter dimension can be improved.

[0016]

According to the first aspect of the present invention, the inner diameter of the cavity surface of the molding die is formed to be larger than the final outer diameter of the molding substrate for the optical disc, and the molding substrate is molded in the molding die. An outer peripheral punch for determining the final outer diameter is provided, and after setting the end surface of the outer peripheral punch to coincide with the cavity surface of the molding die, the raw material for the molded body is filled in the cavity. Since the outer diameter punch of the formed substrate was determined by pushing out the outer peripheral punch by the punch driving means during the pressure holding step after the completion of filling, distortion was suppressed even in the outer peripheral portion compared to the substrate formed by the conventional method. It is possible to obtain a molded substrate having a highly accurate outer diameter dimension in which good transferability of the information recording surface is maintained, without increasing the number of subsequent steps.

According to a second aspect of the present invention, a circular cavity surface having a diameter larger than a final outer diameter of a molded substrate for an optical disk is formed in a molding die, and a position for determining the final outer diameter is formed. Since an outer peripheral punch is formed on the outer peripheral punch and a punch driving means for driving and controlling the outer peripheral punch is provided, by filling the molding resin into the cavity, the outer peripheral punch located on the outer peripheral portion is operated. It is possible to manufacture an optical disk substrate having high accuracy and a small amount of eccentricity.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a configuration of a molding die that is an embodiment of the present invention.

FIG. 2 is a process chart showing a method for producing an optical disc substrate.

[Explanation of symbols]

 1a Cavity surface 2a Cavity surface 4 Molded substrate 5 Peripheral punching punch 6 Punch driving means 9 Molded material A A cavity r Final outer diameter

Claims (2)

[Claims] 1. An outer circumference for determining the final outer diameter in the molding die for molding the molding substrate, wherein the inner diameter of the cavity surface of the molding die is made larger than the final outer diameter of the molding substrate for the optical disk. A punching punch is disposed, and after setting the outer peripheral punching punch so that the end surface of the punch coincides with the cavity surface of the molding die, the cavity is filled with a raw material for a molded body,
A method for producing an optical disk substrate, characterized in that the outer diameter punch is pushed out by a punch driving means during a pressure-holding step after completion of filling to determine the outer diameter of the molded substrate. 2. Forming a circular cavity surface having a diameter larger than the final outer diameter of a molded substrate for an optical disc,
A molding die, wherein an outer peripheral punch is formed at a position for determining the final outer diameter, and punch driving means for driving and controlling the outer peripheral punch is provided.