JP3229367B2 - Stamper punching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is a compact disc BACKGROUND OF THE relates to an improvement of the punching device stun path to be used for transfer molding of the laser disk.

[0002]

2. Description of the Related Art Electroforming of a conventional stamper used for molding a disk-shaped recording medium as a digital information recording medium such as a compact disk (CD) or a laser disk (LD) or an analog information recording medium such as an LP record. As a processing method, for example, there is a method performed in steps (1) to (5) in FIG. That is, step (1) first shows a glass substrate 1 which has been circularly cut to a required size and has been polished, and in step (2), the glass substrate 1 has a thickness of 1,000 to 2, corresponding to the signal groove depth. A photoresist 2 is applied to a thickness of 2,000 mm by spin coating. In step (3), the glass substrate 1 fixed by suction on a rotating jig (turntable) (not shown) is irradiated with a laser beam while being exposed to light to be exposed. To obtain a preformat pattern having fine irregularities according to the recorded information by developing from step (4).
Then, a conductive film 3 of 500 to 1,000 ° is formed on the preformat pattern by sputtering or the like, and then Ni is electroformed using the conductive film 3 as a cathode to obtain a thickness of about 0.2 to 0.3 m / m. Is formed.
In step (5), the glass substrate 1 is peeled off and the resist 2
The master 4 is formed by removing and cleaning. The master 4 is subjected to a release coating process, and then a Ni layer obtained by subjecting the Ni layer to electroforming is formed to form a mother. Further, after the mother is subjected to a release coating process, Ni electroforming is performed. By applying the stamper, a stamper (sun) having a thickness of about 0.2 to 0.4 m / m is obtained, and the recording medium made of plastic is formed by injection molding using the stamper. Using the mother, the stamper is completed by punching with a punching device for drilling a center hole and shaping the outer peripheral shape.

In general, in press-cutting of a metal plate, if the height of a burr formed at a punched portion by a cutting blade is approximately 0.1 mm or less, good quality is obtained. Even if it is a burr,
Since the optical properties (birefringence) and the mechanical properties (tilt mRad) of the finally obtained plastic molded article are likely to be significantly affected, the burr generation rate and the burr height are reduced to the utmost. Is strictly required. In addition, the presence of burrs in the stamper causes non-uniform peeling behavior when peeling between the mold, plastic resin, and the stamper in the injection molding using the stamper. It is known that this causes the generation of a recollision pit (ghost).

For this reason, deburring work of the edge of the stamper is manually added after the above-described press punching process. During the finishing work, metal dust is mixed into the recording surface, and the stamper is bent and deformed. There is a high risk of causing defects such as damage, an increase in the defect rate, and the like. FIG. 6 is an enlarged view showing a state of a punching process using a conventional cutting blade, in which a clearance CL1 between an upper blade 1 and a lower blade 2 for cutting a center hole or an outer peripheral portion of a work (stamper) 3 is shown. Since the thickness is set to 9% or more of the thickness of the work, a part of the punched portion causes plastic fracture to generate the burr portion 4. Next, FIG. 7 shows a state in which punching is performed with the clearance set to 8% or less of the workpiece thickness. In this case, a region to be shaved (shearing while rubbing) is located at the center of the shear fracture portion. to be born. In this state, the surface pressure is extremely increased, and the blade is damaged, and the adhesion of nickel forming the stamper is likely to occur. Further, plastically deformed sagging portions are formed in upper and lower portions of the area to be shaved.

[0005] The accuracy of the center hole diameter of the optical disk is such that the clearance is in the range of +5 to +15 µm with respect to the target hole diameter, and the tolerance is + tolerance. On the other hand, the press ring used to press the inner diameter of the stamper in the injection mold is set to a tolerance of -15 to -25 μm. In the case where the inner diameter holding ring manufactured within the range of the minus tolerance is inserted and pressed into the center hole of the stamper manufactured within the range of the plus tolerance, eccentricity of up to 40 μm may occur. However, there is a possibility that the result of narrowing the margin of the track deflection specification value (60 μm or less) in the medium may be caused.

Next, FIG. 8 shows a state in which a center hole of the stamper 3 is punched by a punch 7 while the stamper 3 is sandwiched between the die 5 and the knockout plate 6. In this conventional method, a knockout plate is used. And the stamper are in surface contact with each other, and the contact area is large, so that foreign matter 8 easily enters between the knock-out plate 6 and the stamper 3 which are biased by the spring. Indentations will be formed on the surface.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and eliminates the need for finishing work for deburring after punching, and furthermore, the eccentricity of the media is determined by the tolerances of the stamper and the presser ring. It is an object of the present invention to provide a punching device such as a stamper that can solve the problem caused by the above.

[0008]

According to a first aspect of the present invention, there is provided a punching apparatus provided with a cutting blade for punching a central portion and an outer peripheral portion of a stamper for forming a recording medium on a disk. The clearance between the upper blade and the lower blade, which constitute the above, is 8% or less of the thickness of the stamper and larger than 0 μm.
And simultaneously hear set, the surface roughness of the upper and lower blades Rma
x is 0.1 s or less, and the surface hardness of each blade is Hv50.
0 or more, and each blade is surface-treated by titanium nitride (TiN) or ion nitriding to reduce the friction coefficient.

[0009]

[0010]

[0011] The present second invention, the position of the distal end portion of the upper blade for cutting the outer peripheral portion of the stamper thickness is t, the tip portion of the cutting edge for cutting the central portion of the stamper by arranging the height h (1 / 2t <h < t) amount corresponding lower side than the position of, allowed start the cutting of the central portion in the middle cut of the outer peripheral portion, it is amplified in the middle peripheral portion cut by the cutting edge The cutting force by the cutting blade is amplified using the cutting energy.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 (a) and 1 (b) are views showing a punched state of a center hole or an outer peripheral portion of a stamper according to a preferred embodiment of the present invention. As shown in FIG. Radial clearance between the workpiece 3 and 8% or less of the thickness of the workpiece 3 ,
And at the same time, set to be larger than 0 μm,
Surface roughness Rmax of 0.1 s or less, furthermore, the surface hardness of each cutting edge is set to Hv500 or more, and the tip R of each cutting edge is set to 0.05 mm or less, and each cutting edge is further reduced to reduce the friction coefficient. Is surface-treated by titanium nitride (TiN) or ion nitriding.

When repeated punching experiments were carried out with a punching apparatus having the above conditions, the life could be extended to such an extent that 200 or more workpieces could be punched without shaving as shown in FIG. It has been found. Furthermore, when the center hole and the outer peripheral portion of the stamper are simultaneously punched by a conventional punching device, the cutting start timing of the center hole punching cutting edge and the cutting start timing of the outer peripheral portion punching edge are completely matched. With the positions of the upper blades set at the same level, each blade is fixed to the pressing means of the cutting device. For this reason, in order to perform high-speed punching, it was necessary to increase the speed by a press device equipped with an accumulator and the like. However, in the present invention, as shown in FIG. By setting the respective cutting start positions of the cutting blades (punches, dies) 12 and 13 for punching the center hole 3a to be less than the thickness t of the work 3 and not less than 1/2, in other words, In the illustrated example, the position of the tip of the upper blade 10 for cutting the outer peripheral portion is higher than the position of the tip of the punch 12 for cutting the central portion by a height h.
By arranging it below by (1 / 2t <h <t), the cutting of the central portion is started during the cutting of the outer peripheral portion or immediately before the end of cutting. In FIG. 2, reference numeral 14 denotes a knockout plate.

According to the embodiment shown in FIG. 2, the timing for completing the removal of the center hole 3a is slightly delayed from the timing for completing the punching of the outer peripheral portion. off using the cutting energy
The cutting force of the blade 12 can be amplified. Therefore, for example, even if the force normally required for punching the center by the cutting blade is 2 ton, according to the present embodiment, 9 ton is required.
Thus, a pressing force of n can be obtained. As a result,
High-speed punching can be performed without increasing the output of the pressurizing means of the cutting device only by slightly shifting the fixing position of each cutting blade for cutting the outer periphery and the center. As a result, it is possible to prevent plastic deformation in the punching of the center hole and obtain a highly accurate roundness.

3 (a) and 3 (b) show another embodiment of the present invention. FIG. 3 (a) is a sectional view showing a state in which a center hole of a stamper is punched by the punching device of the present invention. (b) is a diagram showing the shape of the recess formed in the stamper. What is characteristic in this embodiment is that the center hole 14 of the knockout plate 14 for holding the periphery of the center hole 3a of the stamper 3 is provided.
An annular ridge 14b having a wedge-shaped cross section is protruded along the periphery of the hole 14a concentrically with the hole 14a, and the annular ridge 14b is punched by the cutting blade 12 while being pressed against the periphery of the center hole 3a of the stamper. Thus, concentric indentations 3b are formed in the peripheral portion of the center hole 3a of the stamper 3.
By reducing the contact area between the knockout plate 14 and the stamper 3 as described above, not only the probability of occurrence of foreign matter entrapment is reduced, but also an acute wedge-shaped indentation 3b is positively formed as described later. The indentation 3b is used to prevent the displacement of the stamper in the mold during injection molding.

FIGS. 4 (a) and 4 (b) are an explanatory view showing an injection molding state using the stamper having the above-mentioned indentation and an explanatory view showing a conventional injection molding state. As shown in (b), in the related art, the stamper 3 is sandwiched between the dies 20 and 21 and at the same time, the pressing ring 22 is inserted into the center hole 3a of the stamper 3 and the tip of the pressing ring is screwed into one of the dies 20. Although the conventional holding ring is merely a T-shaped member having a threaded portion at the distal end, it is a means for fixing the positional relationship between the flange-shaped holding portion 22a and the center hole 3a. Did not exist. In other words, since the surface of the pressing portion 22a in contact with the stamper is flat, when there is a large dimensional error between the size of the center hole 3a and the diameter of the rod-shaped portion 22b of the pressing ring, play occurs there. There is a possibility that the stamper may move in the rotation direction due to the flow pressure of the molten resin introduced from the flow path 21a. In addition, this movement causes the back surface of the stamper to be rubbed. This rubbing is a major cause of shortening the life of the stamper.

On the other hand, in the embodiment of the present invention, the wedge-shaped indentations 3b formed on the stamper are formed on the lower surface (contact surface with the stamper) of the presser portion 22a of the presser ring 22 as shown in FIG.
Since the locking annular ridge 22c that closely fits inside the projection, the wedge-shaped indentation 3b can be pressed by the locking annular ridge 22c to prevent the stamper 3 from shifting. As a result, displacement of the stamper in the rotation direction (small rotation) in the mold and backside rubbing caused by the displacement can be prevented, and the life of the stamper can be improved.

The condition of the shape and dimensions of the annular ridge 14b of the knockout plate 14 is set so that the width is 0.5 mm or less.
By setting the tip R to 0.05 mm or less and the height to 1/4 or less of the thickness of the stamper 3, a disk having an eccentricity of 20 μm or less could be obtained. As a result, it is possible to support a disk drive device of a high-speed rotation specification. The punching device according to the present invention is used for manufacturing a high-precision, high-cleaning nickel stamper used for manufacturing a disc-shaped recording medium such as an optical disk, a compact disk, and a magneto-optical disk. Can be applied to the press punching device.

[0019]

As described above, in the present invention, the radial clearance of the upper and lower cutting blades for punching is set to 8% or less of the thickness of the work (however, larger than 0 μm) , but the cutting edges 1 and 2 The surface roughness Rmax is set to 0.1 s or less, the surface hardness of each cutting edge is set to Hv500 or more, and the tip R of each cutting edge is set to 0.05 mm or less. Since the surface treatment is performed by titanium nitride (TiN) or ion nitriding treatment, a finishing operation for removing burrs after punching is not required, and the yield can be improved.

When punching the center of the stamper with a punch, an annular ridge 14b having a wedge-shaped cross section is formed around the center hole 14a of the knockout plate for holding the center of the stamper with the die. By doing so, an annular indent 3b is formed concentrically with the center hole 3a to be formed in the center of the stamper, and an annular annular ridge 22c provided on the pressing ring 22 during injection molding is fitted to the indent 3b. Since the medium (disk) is fixed in a squeezed state, the amount of eccentricity of the medium (disk) is not determined by the respective tolerances of the stamper and the holding ring, and the amount of eccentricity can be minimized. In addition, since the rotational direction shift of the stamper during injection molding can be prevented, the life of the stamper can be increased. In other words, it is possible to prevent the rotation of the stamper due to the imbalance of the resin injection power during molding,
The micro abrasion generated on the mold and the back surface of the stamper is eliminated, and the life of the stamper can be greatly improved. Also, by utilizing the annular mark of the knockout plate, eccentricity during molding can be prevented, and a disk with small radial runout acceleration can be obtained stably.

Further, the timing of starting the cutting by the outer peripheral cutting blade of the stamper is slightly earlier than the timing of starting the cutting by the central cutting blade, specifically, the upper blade for cutting the outer peripheral portion. Is positioned at a height h (1) higher than the position of the tip of the punch for cutting the center.
/ 2t <h <t), the center portion is started to be cut during or just before the end of the outer peripheral portion, and the outer peripheral portion is cut by the cutting blade or immediately before the end. Using the amplified cutting energy, the cutting force of the punch can be amplified. Accordingly, high-speed punching can be performed without increasing the output of the pressurizing means of the cutting device. As a result, it is possible to prevent plastic deformation in the punching of the center hole and obtain a highly accurate roundness. Change
According to the first aspect of the present invention, the product of the stamper processed portion is provided.
Quality can be obtained stably. In particular, deburring work
It can be omitted, and improvement in yield can be expected. Also, the life of the punching blade
By improving the life, repolishing costs can be reduced. Claim 2
In the invention of the above, the unbalance of the resin injection power during molding
Can prevent the stamper circuit associated with
The micro abrasion on the back of the
Life is greatly improved. In the invention of claim 3,
Forming by utilizing the annular mark on the knockout plate
Medium eccentricity can be prevented, and the radial runout acceleration is small.
A stable disk can be obtained. Claim 4
In the invention of the above, high-speed punching is possible even with a low output device
No burrs and center hole processing with good roundness is possible
It works.

[Brief description of the drawings]

1 (a) and 1 (b) are views showing a punching state by a punching device according to a preferred embodiment of the present invention.

FIG. 2 is a diagram illustrating a punched state according to another embodiment of the present invention.

FIGS. 3 (a) and 3 (b) are views showing a punched state at the center and a shape of a stamper after punching according to another embodiment of the present invention.

FIGS. 4A and 4B are an explanatory view showing an injection molding state using a stamper having an indentation and an explanatory view showing a conventional injection molding state.

FIGS. 5 (1) to 5 (5) are explanatory views of a conventional stamper electroforming method used for forming a disc-shaped recording medium.

FIG. 6 is an explanatory diagram showing a punching state according to a conventional example.

FIG. 7 is a diagram illustrating a punching state when a radial clearance between upper and lower cutting blades is set to 8% of a work thickness.

FIG. 8 is a schematic structural explanatory view of a conventional device for punching a center portion of a stamper.

[Explanation of symbols]

1 upper blade, 2 lower blade, 3 work, 3a center hole, 3b
Indentation, 10, 11 cutting edge, 12, 13 cutting edge, 14
Knockout plate, 14a center hole, 14b20,
21 mold, 22 press ring, 22a flange-shaped press section, 22b rod-shaped section, 22c locking annular ridge,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 7/26 B26F 1/44 B26F 1/02

Claims (2)

(57) [Claims] 1. A punching device provided with a cutting blade for punching a central portion and an outer peripheral portion of a stamper for forming a disk-shaped recording medium, wherein a clearance between an upper blade and a lower blade constituting the cutting blade is provided. Is set to 8% or less of the thickness of the stamper and larger than 0 μm, and the surface roughness Rmax of the upper blade and the lower blade is set to 0.
1s or less, the surface hardness of each blade is Hv500 or more, and each blade is made of titanium nitride (Ti) to reduce the friction coefficient.
N) or punching device stun path, characterized in that the surface treated by plasma nitriding. 2. A position of a tip of an upper blade for cutting an outer peripheral portion of the stamper having a thickness t is higher than a position of a tip of a cutting blade for cutting a center of the stamper. H
By arranging only under side (1 / 2t <h <t ) min, allowed start the cutting of the central portion in the middle cut of the outer peripheral portion, by using the amplified cut energy halfway outer peripheral portion cut by the cutting edge punching apparatus Stan path according to claim 1, characterized in that allowed amplification of the cutting force by the cutting edge.