JP4369381B2 - Disk substrate molding die and disk substrate molding method - Google Patents

Description

  The present invention relates to a disk substrate molding die, a disk substrate molding method, and a disk obtained by bonding together disk substrates molded by the disk substrate molding method.

  Conventionally, what is shown by patent document 1 is known as a shaping | molding die of a disk substrate. In Patent Document 1, a fixed mold and a movable mold that are arranged to face each other and cooperate to form a cavity when the mold is clamped, and are arranged so as to be able to protrude from the center of the opposed surface of the movable mold. A male cutter, a mescutter disposed so as to receive the male cutter in the center of the opposing surface of the fixed mold, and a sprue bush supplied with a melt-plasticized resin material supported in the mescutter. It is described that a disk substrate molding die is provided and gate cutting is performed between the disk cutter and the mescutter by projecting the male cutter. FIG. 5 and the like of Patent Document 1 show a molding die for a general mescutter and male cutter disk substrate. In the disk substrate molding die shown in FIG. 5 and the like, as shown in FIG. 10, there is a slight clearance between the two when the male cutter is protruded into the mescutter. As shown, there is a problem that burrs having a height higher than that of the central area surface of the disk substrate are generated at the end of the inner peripheral hole of the disk substrate. The burrs are easily pulverized in a subsequent process, and when the pulverized burrs fall on the transfer surface of the disk substrate, defective products are generated. In addition, the disk substrate molded with a mold having a stamper attached to the fixed mold side has a problem that burrs come into contact with each other when stuck to another disk substrate.

Japanese Patent Laid-Open No. 11-240048 (Claim 1, FIG. 5, FIG. 10, FIG. 12)

  In the present invention, in view of the above problems, burrs having a height higher than the central area surface of the disk substrate are generated at the end of the inner peripheral hole of the disk substrate when the disk substrate is molded, and the burrs are pulverized in a subsequent process to form the disk substrate. The purpose of the disk substrate is to solve the problem that it may fall on the transfer surface and cause defective products, or the burrs may come into contact with each other when stuck to another disk substrate. An object is to provide a molding die and a molding method.

According to a first aspect of the present invention, there is provided a molding die for a disk substrate, wherein a fixed die and a movable die that cooperate to form a cavity when the die is aligned, and a movable die that is disposed on the movable die. A disk substrate comprising: an oscutter; a mescutter that is disposed in a fixed mold and performs gate cutting between the oscutter; and a sprue bush that is disposed or integrally formed in the inner peripheral hole of the mescutter and is supplied with molten resin. In the molding die, an annular protrusion is formed on the front end surface of the mescutter adjacent to the outer peripheral end surface and the inner peripheral hole, and the annular protrusion has a height from the outer peripheral end surface to the top. It is characterized in that it has an inner peripheral portion of 30 μm to 80 μm and the same diameter as the inner diameter of the mesh cutter, a top portion having a radial width of 6 to 20 μm, and an inclined surface between the top portion and the base portion .

According to a second aspect of the present invention, a molten resin is supplied to a cavity formed by combining a fixed mold and a movable mold through a sprue bush disposed in the fixed mold. In the disk substrate molding method in which gate cutting is performed between the male cutter and the mescutter disposed in the movable mold, the tip surface of the mescutter is annularly formed adjacent to the outer peripheral tip surface and the inner peripheral hole. A protrusion is formed, and the annular protrusion has an inner peripheral portion having a height from the distal end surface near the outer periphery to the top of 30 μm to 80 μm and the same diameter as the inner diameter of the mescutter, and a base having a radial width of 80 μm to 120 μm. And an inclined surface between the top and the base, and after the molten resin is supplied to the cavity , the gate is cut with the mescutter by projecting the male cutter .

  According to the disk substrate molding die and the molding method of the present invention, a height of 30 μm to 80 μm is formed adjacent to the inner peripheral hole on the tip surface of the mescutter having the inner peripheral hole into which the male cutter of the disk substrate molding die is inserted. Therefore, a burr having a height higher than that of the central area surface of the disc substrate does not occur at the end portion of the inner peripheral hole of the disc substrate to be molded. Therefore, the burrs are crushed in a subsequent process and dropped on the transfer surface of the disk substrate, which rarely causes defective products. Therefore, the yield in manufacturing a disk in which the disk substrate formed by the disk substrate molding die and the molding method is bonded is high.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of an essential part of a molding die for a disk substrate according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the mescutter in the disk substrate molding die of the present embodiment. FIG. 3 is a cross-sectional view of the vicinity of the center opening of the disk substrate formed by the disk substrate molding die of the present embodiment. As shown in FIG. 1, a disk substrate molding die 11 is composed of a fixed die 12 and a movable die 13, and a cavity 14 having a variable volume is formed between the two molds 12 and 13 which are matched with each other. It is supposed to be formed. A fixed mold 12 attached to a fixed plate of an injection molding machine (not shown) includes a fixed mold plate 15, a fixed mirror plate 17 fixed to the fixed mold plate 15 via a fixed back plate 16 and having a cooling flow path, and a fixed mold. The gate insert 18 disposed in the inner peripheral hole of the plate 15, the fixed back plate 16, and the fixed mirror plate 17, the mescutter 19 disposed in the inner peripheral hole of the gate insert 18, and the inner peripheral hole 19 a of the mescutter 19 It consists of sprue bush 20 etc. by which a front-end | tip part is inserted.

  In this embodiment, the cavity 14 surface of the gate insert 18 and the distal end surface 19b near the outer periphery of the mescutter 19 are provided at the same height. The mesh cutter may be formed integrally with the gate insert. Moreover, in this embodiment, the front end surface 20a on the cavity 14 side other than the sprue hole in the sprue bush 20 is a flat surface. The front end surface 20 a is located deeper in the inner peripheral hole 19 a of the mescutter 19 as viewed from the cavity 14 side than the front end surface 19 b near the outer periphery of the mescutter 19. A recess into which the male cutter 28 can be inserted is formed by the distal end surface 20 a of the sprue bush 20 and the inner peripheral hole 19 a of the mescutter 19. A cooling channel for cooling the sprue bush 20 and the like is formed between the mescutter 19 and the sprue bush 20. In addition, about a sprue bush, it is not limited to what a front end surface consists of a flat surface. Alternatively, an air flow path may be formed between the sprue bush and the mescutter, or the sprue bush may be movable with respect to the mescutter by a predetermined distance in the axial direction. Further, the sprue bush and the mesh cutter may be formed integrally.

  As shown in FIG. 1, a movable mold 13 attached to a movable platen of an injection molding machine (not shown) includes a movable mold plate 21, a movable back plate 22 fixed to the movable mold plate 21, and a movable mold plate 21. A movable mirror plate 23 fixed through the movable back plate 22 and having a cooling channel, a stamper 24 disposed on the surface of the movable mirror plate 23, and an inner peripheral hole of the movable mirror plate 23, the stamper An inner peripheral stamper holder 25 for holding 24, a stationary sleeve 26 disposed in an inner peripheral hole of the inner peripheral stamper 25, and an ejector sleeve disposed in an inner peripheral hole of the stationary sleeve 26 and movable in the axial direction. 27, a cylindrical male cutter 28 which is disposed in the inner peripheral hole of the ejector sleeve 27 and is movable in the axial direction, and is inserted into the inner peripheral hole of the male cutter 28 and is movable in the axial direction so A projecting pin 29 engaging portion is provided for locking the disc substrate A to the movable mold 13 side, consisting of an outer peripheral stamper holder or the like (not shown) for holding the outer peripheral portion of the stamper 24. In the present embodiment, the tip surface of the male cutter 28 is a flat surface, but is not limited thereto.

  Next, the shape of the mesh cutter 19 of this embodiment will be further described with reference to FIG. The mescutter 19 has a substantially cylindrical shape whose diameter increases stepwise toward the side opposite to the cavity. The shaft core is formed with the inner peripheral hole 19a into which the sprue bush 20 and the male cutter 28 are inserted as described above. The inner peripheral hole 19a has the same diameter at least in the portion where the male cutter 28 is inserted. An annular projecting portion 30 is formed on the distal end surface of the mescutter 19 near the inner peripheral portion on the cavity 14 side so as to protrude toward the cavity 14 adjacent to the inner peripheral hole 19a. In the present embodiment, the annular protrusion 30 has a height H (projection dimension of the annular protrusion 30 toward the cavity 14) from the distal end surface 19 b near the outer periphery of the mescutter 19 of 60 μm. The inner peripheral portion 30 a of the annular protrusion 30 is provided with the same diameter as the inner peripheral hole 19 a of the main body portion of the mescutter 19. The radial width W1 at the top 30b of the annular protrusion 30 is 10 μm. The radial width W2 of the base 30c of the annular protrusion 30 is 100 μm. An inclined surface 30d between the top portion 30b and the base portion 30c of the annular protrusion 30 is a concave R surface toward the inner peripheral portion 30a side and the body portion side of the mescutter 19. In other words, the inclined surface 30d is a gentle curved surface with a gentle inclination near the base 30c and a tight inclination near the top 30b.

  The height H of the annular protrusion 30 is higher than the height of the burr A1 formed between the male cutter 28 and the mescutter 19 at the time of molding, and about 20 μm. What is necessary is just a grade which does not disturb the flow of molten resin. Therefore, the height H of the annular protrusion is desirably 30 μm to 80 μm, more preferably 40 μm to 70 μm. The width W1 of the top of the annular protrusion is preferably about 6 μm to 20 μm. This is because if the top width W1 is larger than this, there is a gap between the burr A1 and the disk substrate body, and the burr A1 is likely to break, and if the top width W1 is too narrow, wear during processing or molding of the mescater. This is not preferable. Moreover, the top part of the annular projection part does not have a clear width and may be gently connected to the inclined surface. Further, the width W2 of the base portion of the annular protrusion is preferably about 80 μm to 120 μm. Further, the inclined surface may be a tapered surface. In addition, all of the above dimensions are those at room temperature, not the dimensions at the time of molding. Further, although the material of the mescutter 19 is stainless steel, depending on the case, the entire surface of the mescutter that contacts the molten resin or only the annular protrusion may be subjected to wear resistance processing by DLC, Tin, chrome plating or the like.

  Next, a disk substrate forming method and a disk manufacturing method manufactured by bonding the disk substrates together will be described. A movable platen of an injection molding machine (not shown) is driven forward, the fixed mold 12 and the movable mold 13 are combined to form a variable volume cavity 14, and a molten resin is formed from an injection apparatus (not shown) via a sprue bush 20. Is supplied. Then, the movable mold 13 is further advanced and the molten resin in the cavity 14 is compressed. Therefore, in this embodiment, the space | interval at the time of injection | emission with the ejector sleeve 27 of the movable metal mold | die 13 and the top part 30b of the cyclic | annular protrusion part 30 of the stationary metal mold | die 12 is wider than the space | interval at the time of shaping | molding completion. And before the cooling and solidification of the molten resin in the cavity 14 is completed, the male cutter 28 disposed in the movable mold 13 is advanced and inserted into the inner peripheral hole 19a of the mescutter 19 by the operation of a driving device (not shown). A gate cut is made. At that time, the male cutter 28 is inserted into the sprue bush 20 side by about 100 μm to 300 μm from the top 30 b of the annular projection 30 of the mescutter 19. The inner peripheral hole 19a of the mescutter 19 including the inner peripheral portion 30a of the annular protrusion 30 and the outer peripheral portion 28a of the male cutter 28 are spaced so that no galling occurs when the male cutter 28 is inserted. When the male cutter 28 is inserted, a burr A1 is formed between the inner peripheral portion 30a of the annular protrusion 30 and the outer peripheral portion 28a of the male cutter 28. However, in this embodiment, the burr A1 is formed with a height of about 20 μm from the portion where the top 30b of the annular protrusion 30 of the mescutter 19 and the outer peripheral portion 28a of the male cutter 28 face each other toward the sprue bush 20 side. However, in the present embodiment, the height of the annular protrusion 30 is 60 μm. Therefore, even if the burr A1 is formed to a height of 20 μm, as shown in FIG. 3, the cavity 14 of the gate insert 18 is formed. Compared to the height of the central area surface A2 of the disk substrate A (the plane located on the inner peripheral side of the surface facing the signal surface A5) formed by the surface and the outer peripheral tip surface 19b of the mescutter 19, the burr A1 The height is formed lower. In particular, in the present invention, the top portion 30b of the annular protrusion 30 is as narrow as 10 μm, and the inclined surface 30d is a concave R surface toward the inner peripheral portion 30a side and the body side of the mescutter 19, so that the disk On the side of the central opening A3 of the substrate A, a convex R surface A4 is provided, and the burr A1 can be further protected.

  Then, the formed disk substrate A is conveyed to a subsequent process, and after passing through a process such as aluminum vapor deposition on the signal surface A5, it is bonded to another disk substrate with an adhesive to manufacture a bonded disk such as a DVD. At this time, the height of the burr A1 formed on the side of the central opening A3 of the disc substrate A is lower than the height of the central area surface A2 of the disc substrate A. Adhering and the disk almost never became defective. Although the bonded disk is described in the present embodiment, the generation of defective products due to the attachment of burrs in the post-process can be reduced for a disk that is not bonded, such as a CD.

  The present invention is not enumerated one by one, but is not limited to the one in the above-described embodiment, and it goes without saying that the present invention is applied to those modified by a person skilled in the art based on the gist of the present invention. It is. Although the case where the stamper 24 is attached to the movable mold 13 has been described in the present embodiment, the presence or absence of the stamper and the mold to which the stamper is attached are not limited. When the stamper 24 is attached to the movable mold 13, the molded disc substrate A is placed with the signal surface A5 as the upper surface and the surface on which the burr A1 is formed as the lower surface, but the burr A1 is in contact with the mounting portion. Since there is no contact, there is an advantage that the burr A1 is not damaged. When the stamper is attached to the fixed mold, the signal surface and the surface on which the burrs are formed are placed as the upper surface, and another disk substrate is bonded with the surface on which the burrs are formed as the lower surface. In this case, there is an advantage that the burrs do not come into contact with each other and are not damaged or get in the way. Therefore, the bonding interval between the disk substrates can be narrowed.

It is principal part sectional drawing of the shaping | molding die of the disc substrate of this embodiment. It is an expanded sectional view of the mescutter in the metal mold | die of the disc substrate of this embodiment. It is sectional drawing of center disk vicinity vicinity of the disc substrate shape | molded by the shaping | molding die of the disc substrate of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Disc board molding die 12 Fixed die 13 Movable die 14 Cavity 15 Fixed mold plate 16 Fixed back plate 17 Fixed mirror plate 18 Gate insert 19 Messutter 19a Inner peripheral hole 19b Outer end surface 20 Sprue bush 20a End surface 21 Movable mold plate 22 Movable back plate 23 Movable mirror plate 24 Stamper 25 Inner circumference stamper holder 26 Stationary sleeve 27 Ejector sleeve 28 Oscutter 28a Outer part 29 Projection pin 30 Annular projection part 30a Inner circumference part 30b Top part 30c Base part 30d Inclined surface A Disk substrate A1 Burr A2 Central area surface A3 Center opening A4 R surface A5 Signal surface H Height (projection dimension of the annular protrusion to the cavity side)
W1 width (the width of the top of the annular projection)
W2 width (width of the base of the annular projection)

Claims (2)

A fixed mold and a movable mold that cooperate to form a cavity when the molds are combined, a male cutter that is disposed in the movable mold and that can be protruded, and a male cutter that is disposed in the fixed mold and the male cutter. In a disk substrate molding die comprising: a mescutter for performing gate cutting at a position, and a sprue bush that is disposed or integrally formed in an inner peripheral hole of the mescutter and is supplied with molten resin.
An annular protrusion is formed on the tip surface of the mescutter adjacent to the outer peripheral tip surface and the inner peripheral hole made of a plane ,
The annular protrusion has an inner peripheral portion having a height from the tip end near the outer periphery to the top of 30 μm to 80 μm and the same diameter as the inner diameter of the mescutter, a top having a radial width of 6 to 20 μm, and the top And a tilting surface between the base and the disk substrate molding die. Molten resin is supplied to the cavity formed by combining the fixed mold and the movable mold through the sprue bush arranged in the fixed mold, and between the male cutter and the mescutter arranged in the movable mold. In the disk substrate molding method that performs gate cutting with
An annular protrusion is formed on the tip surface of the mescutter adjacent to the outer peripheral tip surface and the inner peripheral hole made of a plane ,
The annular protrusion includes an inner peripheral portion having a height from the distal end surface near the outer periphery to the top portion of 30 μm to 80 μm and the same diameter as the inner diameter of the mesh cutter, a base portion having a radial width of 80 μm to 120 μm, and the top portion and has an inclined surface between the base portion, after the supply of the molten resin into the cavity, the molding method for a disk substrate which is characterized in that the gate cut between the female cutter by projecting the male cutter.

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