JPH0579456B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to forming an inner diameter and an outer diameter with precise concentricity on a stamper, which is the basis of an optical disc such as a video disc or a compact disc (digital audio disc). The present invention relates to a precision centering cutting device for cutting.

[Conventional technology and its problems]

Optical disks such as video disks and audio disks have signal pits that record information at high density and are formed as many fine concentric circular grooves. When attempting to manufacture such an optical disc (laser disc) by injection molding of plastic, a stamper must be prepared that corresponds to the negative of the positive optical disc.
Stampers are usually made of hard, sticky, difficult-to-cut materials such as nickel-based alloys, but in order to accurately set this stamper in the injection molding machine and manufacture high-precision optical discs, it is necessary to use a signal pit. It is necessary to cut an inner hole precisely concentric with the multiple concentric grooves in the center of the stamper.

The position of the inner hole and the outer diameter of the stamper to be cut are indicated by concentric markings marked on the stamper in advance. In the past, it was very difficult to set the values to match. Normally, the concentricity required for compact disc stampers was acceptable as long as it had an accuracy of about 10 to 20 microns, but even this was difficult with conventional technology, so high-density information was recorded. Expensive stampers were often ruined during the cutting process.

Furthermore, if possible, it is desirable to increase the concentricity of the stamper inner hole to the order of 1μ, but with conventional technology, such centering is not only almost impossible, but even if it were possible, the accuracy would be limited. It was completely impossible to hold the stamper in place and cut a precise concentric inner hole in the stamper, which is a difficult-to-cut material, and also to cut the stamper's outer diameter concentrically.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the prior art as described above.The present invention has been made in order to solve the problems of the prior art as described above. It is an object of the present invention to provide a device that can hold the hole firmly with concentricity, accurately cut the inner hole without destroying the concentricity, and then cut the outer diameter with precise concentricity.

[Summary of the invention]

In the precision centering cutting device of the present invention, a stamper whose inner diameter and outer diameter are to be cut (hereinafter referred to as a workpiece stamper) is set with high precision concentricity on the rotation center axis of the cutting device, and the outer circumference of the stamper is first The first thing is to have a stamper holder that firmly holds the inner diameter of the inner hole with precision concentricity so that the inner diameter of the inner hole can be cut, and then has a stamper holder that firmly holds the area around the inner hole so that the outer diameter can be cut. It is a characteristic. When this stamper holder is gripped by a chuck at the tip of a hollow spindle shaft that can rotate on the rotation center axis with an accuracy of approximately 1 μ, the concentricity is further finely adjusted to the order of 1 μ, allowing for high magnification. (For example about 200
A measuring section consisting of a microscope (or stereoscopic microscope) with a magnification of ~400 times is installed close to the tip of the spindle shaft, and this measuring section measures the fineness of the stamper by observing the concentricity of the stamper to be cut with respect to the rotation center axis. In addition to making adjustment possible, the approach of the cutting edge of the cutting tool to the marking mark on the workpiece stamper set to precise concentricity is observed, and precise cutting is made possible with the cutting edge matching the exact position.
The measuring section is configured to be movable between such an observation position and a non-observation position, and can be moved to the non-observation position when the stamper holder is attached to and removed from the hollow spindle shaft. At the tip of the spindle shaft,
A plurality of fine adjustment screws are provided for finely adjusting the stamper holder in the radial direction in order to correct the misalignment in microns observed by the microscope. After the desired concentricity has been confirmed by the measuring section, a cutting tool that can approach the front surface of the stamper holder is used to cut the inner diameter and outer diameter of the stamper to be cut, which are being observed by the measuring section. A turret having a turret is provided in front of the tip of the spindle shaft.

According to the present invention, the stamper to be cut is first fastened and fixed onto the stamper holder with a certain degree of concentricity,
After attaching this stamper holder to the tip of the hollow spindle shaft that rotates during cutting, fine adjustments are made with even higher precision. High-precision cutting of the inner diameter (on the order of 1 μm) is performed easily and reliably while confirming the precise alignment between the marking mark and the cutting edge, and then the center of the stamper to be cut is firmly held in the holder. Since the outside diameter is cut in the same way, centering with the desired precision and cutting of concentric circles can be achieved easily and with extremely high precision, and unlike conventional methods, the stamper is not destroyed at the cutting stage (due to defective products). ) can be reliably prevented.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the entire stamper precision centering cutting device according to the present invention.

A hollow spindle shaft 3 extends horizontally through a headstock body 2 supported on a machine housing 1.
is rotatably supported. The hollow spindle shaft 3 is adapted to be able to rotate with precise concentricity on its central axis. Although only the front end of the hollow spindle shaft 3 is visible in FIG. 1, it passes through the inside of the headstock body 2 and receives rotational input from the power source inside the housing 1 inside the drive section 4. It's getting old. 1a on the side wall of the housing is a speed change switch for changing the rotation speed of the spindle shaft 3, R ₁ and R ₂ are switch buttons for changing the rotation direction between forward and reverse directions, and S is a power switch. The configuration of the hollow spindle shaft 3 that rotates with high precision and its drive unit 4, as well as the chuck 5 and its operating mechanism described below are related to other patents and utility models owned by the present applicant, and are outside the scope of the present invention itself. I will omit the details as there are.

The vicinity of the front end of the hollow spindle shaft 3 is shown in the enlarged cross-sectional view of FIG. 2, and the chuck 5 inserted therein extends through the hollow spindle shaft 3 to the rear end, and an operating lever near the rear end of the chuck is inserted therein. 5a (FIG. 1) can be slid in the axial direction as shown by arrows A and B in FIG. 2 by operating it left and right A-B. The front end of the chuck 5 has a gripping hole 5b.
(Fig. 2), and by inserting the shaft portion 11a of the stamper holder 10, which will be described later, and pulling the chuck 5 in the direction of arrow A, the shaft portion 11a is strongly gripped, and the hollow spindle shaft 3 and They will be able to rotate as one. As is clear from FIG. 2, a screw holder 6 is fixed to the front end of the hollow spindle shaft 3, and its through center hole 6a is connected to the shaft portion 11a.
The diameter is such that it can be inserted loosely. A plurality of fine adjustment screws 7 are provided on the outer periphery of the screw holder 6, the tips of which are exposed into the through-center hole 6a. Preferably, the number of fine adjustment screws 7 is three or more, for example four, or six.
It is best to space the books evenly apart. In FIG. 1, three fine adjustment screws 7 are shown.

A stamper holder 10 according to the present invention is attached to the chuck 5 and screw holder 6 at the front end of the hollow spindle shaft 3, as shown in FIG. 1, FIG. 2, or FIG. 3. Stamper holder 1
0 is installed as shown in Figure 2 or 3, and the disassembled parts are shown in Figure 4 (flat plate), Figure 5 (outer clamping plate), and Figure 6 (inner clamping plate). It is as shown in . FIG. 7 is a plan view of the stamper to be cut.

The first component constituting the stamper holder 10 is a flat plate 11. A shaft portion 11a is provided protruding from the center of the back surface of the flat plate 11. The diameter of the shaft portion 11a is made smaller than the inner diameter of the through center hole 6a of the screw holder 6, as described above. The front surface of the flat plate 11 is disk-shaped, and a stepped portion 11b is formed at the periphery thereof. Screw hole 11 in the center of the front of the flat plate 11
c is bored, and is used for fixing an inner tightening plate 14, which will be described later. An outer annular groove 11d and an inner annular groove 11e are formed on the front surface of the flat plate 11 in accordance with the outer diameter and inner diameter of the stamper to be cut.

The second component of the stamper holder 10 is the outer clamping plate 12. As shown in FIG. 2, an annular projection 12a is formed on the outer peripheral edge of the back surface of the flat plate 1.
1 engages with the stepped portion 11b on the outer peripheral edge. Outer tightening plate 12
The main part is composed of a plurality of presser tongue pieces 12b extending radially inward from the annular main body part. In the example shown in FIG. 5, the presser tongues 12b are formed as four tapered tongues. There is a space between the tongue pieces 12b. Outer tightening plate 12
A screw hole 12c is drilled near the outer periphery of the flat plate 11, and a screw 13 is screwed into the corresponding screw hole (indicated by a broken line in FIG. 4) near the outer periphery of the flat plate 11, as shown in FIG. In this way, the outer fastening plate 12 and the flat plate 11 can be fixed together. At this time, there is a stamper P between the flat plate 11 and the outer clamping plate 12.
The central region is open, and the clamping force is mainly held near the outer periphery (Fig. 2).

The stamper P to be cut is shown as a plan view in FIG. 7, and the inner diameter to be cut is indicated by a marking mark m in the central region, and the outer diameter is similarly indicated by a marking mark n.

The next part of the stamper holder 10 is the inner clamping plate 1
It is 4. As shown in FIG. 6, the planar shape of the inner clamping plate 14 has four presser tabs 14a extending radially outward from the center, and a screw hole in the thick center (see FIG. 3). 14b is drilled, and this screw hole 14
A fastening screw 15 is screwed into the screw hole 11c at the center of the flat plate 11, and the inner fastening plate 14 is fastened to the flat plate 11 as shown in FIG. As is clear from the superimposed view of FIG. 5 and FIG. The dimensions are such that it does not interfere with the
The shape is such that it can contact the stamper P over as wide an area as possible and press the stamper.

Next to the stamper holder 10, another important feature of the present invention is the measuring section 16 shown in FIG. The measurement unit 16 has a microscope consisting of a lens barrel 20, an objective lens 21, and an eyepiece 22 attached to the tip 19 of an arm 18 that is attached to a mounting body 17 supported on the upper part of the headstock body 2 so as to be pivotable up and down. It consists of A stereoscopic microscope can also be used instead of the illustrated microscope. To adjust the focus of the microscope, the mounting body 17 can be slid back and forth by turning a screw 17a. Instead of screws,
A rack may also be used. Since the lens barrel 20 is configured to be able to swing in a vertical plane parallel to the front surface of the stamper holder 10 about the pivot shaft 23 extending from the arm 18, the objective lens 21 is able to move around the stamper P on the stamper holder 10. It can be moved to both positions to observe the inner diameter m and outer diameter n (Fig. 7). 24
and 25 (FIG. 1) are fixing screws, respectively. In Fig. 1, the microscopes 20, 21, and 22 are at the observation position. At this position, the microscopes observe whether the inner diameter m and outer diameter n of the stamper to be cut are precisely concentric with the spindle rotation center axis, and In addition to making it possible to adjust the extension, it is also possible to continuously observe whether or not the blade 28, which will be described below, is accurately aligned with a designated cutting position before the start of cutting and during the execution of cutting. Further, when the microscope holder 10 is attached to and detached from the spindle shaft 3, a part of the arm 18 of the microscope is flipped up to a non-observation position as shown by the chain line in FIG.

Finally, a tool rest 27 is provided on a guide surface 26 supported on the upper surface of the machine housing 1, and is movable parallel to the axis of the hollow spindle shaft 3 and in a transverse direction. Fixed. To move the cutter 28 in the axial direction, the tool rest 27 is moved forward and backward relative to the spindle shaft 3 using the lever 27a or the screw handle 27b. The tool rest 27 is also moved transversely to the spindle shaft 3 by the lever 27c or the screw handle 27d, and these movements cause the cutting edge of the tool 28 to precisely match the marking marks m and n on the stamper P on the workpiece. can be positioned as In addition,
The structure of this tool rest 27 itself is outside the scope of the present invention, so details will be omitted.

Next, the operation of the apparatus of the present invention having the above configuration will be explained. First, support the flat plate 11 so that its front surface is as horizontal as possible, and place the inner diameter m
Then, a stamper P to cut the outer diameter n is placed on the stamper P. The center part m of the stamper P has not yet been hollowed out, but the outer annular groove 11 on the flat plate 11 has been cut out.
d or other appropriate marks so that the center O coincides with the center of the flat plate as much as possible, then cover the outer fastening plate 12 over it and fasten it to the flat plate 11 with screws 13. Before tightening the screw 13, it is recommended to visually measure the distance between the inner end of the presser tongue piece 12b and the marking mark m, and adjust the stamper P slightly so that the center O is aligned with the center of the flat plate as much as possible. The stamper holding plate 10, which consists of the outer clamping plate 12 and the flat plate 11 on which the stamper P is clamped and fixed, is attached to the tip of the spindle shaft as shown in FIG. 2. Shaft portion 11a of holding body 10
Although the rear end is firmly held by the chuck 5, there is a gap between it and the through hole 6a of the screw holder 6, so there is room for fine adjustment.
Since the stamper P is only tightened by the outer clamping plate 12 and the inner clamping plate 14 is not attached yet, the marking mark m at the center of the stamper can be observed from the front side of the holder 10.

Here, the microscope of the measuring section 16 is lowered to the position shown in FIG. 1, the objective lens 21 is adjusted to the position where the marking mark m is observed, and the focus is adjusted. The microscope preferably has a high magnification of, for example, 100 times or more, preferably 200 to 400 times, and the eyepiece lens 22 has a magnification of 0.1 to 0.5.
It is best to have a scale of about mm. While the stamper holder 10 is rotated by the hollow spindle shaft 3, the deviation of the marking mark m is observed. A plurality of fine adjustment screws 7 are alternately finely adjusted depending on the degree of wobbling so that the locus of the marking mark m passes through the same point on the eyepiece 22. As a result of fine adjustment, a high precision concentricity of 1 μm or less can be obtained. If the position of the objective lens 21 at this time is projected onto the stamper to be cut in FIG. 7, the position will be as shown by a chain line 21.

Next, move the tool post 27 to align the cutting edge of the tool 28 with the marking mark m, and then move the tool rest 27 to align the cutting edge of the tool 28 with the marking mark m.
- The inner diameter m of the stamper is cut by rotating the holder 10. In the actual operation, while looking through the microscope, slowly turn the screw handle 27b to bring the cutter 28 slightly closer to the stamper P to be cut, and at the same time, move the other screw handle 27d slightly so that the cutting edge is slightly inside the marking mark. Make a trial cut so that it hits the (spindle shaft 3 is rotating). The approximate position of the cutter 28 at this time is projected by a chain line 28 in FIG. Then, while looking through the microscope, the handle 27d is further moved slightly to bring the cutting edge closer to the marking mark m, and the actual cutting is performed by carefully and precisely aligning the cutting edge with the marking mark m. In this way, cutting is carried out while constantly observing the accuracy with a microscope, so that the formed inner hole M (shown in the central region of the stamper P in FIG. 3) achieves highly accurate concentricity.

Next, the inner clamping plate 14 is placed in the formed inner hole M and fastened to the flat plate 11 with screws 15 (FIG. 3). The presser tongue piece 14a of the inner tightening plate 14 is
Since the stamper P is pressed down from the center of the stamper P toward the outer periphery instead of the outer clamping plate 12, the outer clamping plate 12 is removed this time and the outer diameter n of the stamper P is cut. At this time, the outer diameter of the cutting edge of the cutter 28 is n.
Apply it slightly outward (position indicated by chain line 28' in Fig. 7), and gradually move the cutting edge closer to the marking mark n while looking through the microscope (chain line 21'). In this way, a stamper is completed, which has an inner hole M and an outer diameter that achieve the desired highly accurate concentricity.

The present invention further includes a temporary centering device that facilitates initially attaching the stamper to be cut to the flat plate as concentrically as possible. This temporary centering device is as shown in FIG. A flat plate shaft portion 11a is located near one end of the guide block 30 whose upper surface constitutes a plane on which the flat plate 11 is placed.
A guide hole 31 is formed to rotatably receive the microscope, and a microscope mounting hole 32 is formed near the other end. An arm 34 is supported by a mounting shaft 33 that is rotatably inserted into the mounting hole 32, and a microscope 35 is mounted on the tip of the arm 34. 35a is an objective lens, and 35b is an eyepiece lens with a scale. A microscope with a magnification of approximately 50 to 100 times is sufficient.

To use this device, place the flat plate 11 on the upper surface, insert its shaft portion 11a into the guide hole 31 as shown in the figure, place the stamper P to be cut on the upper surface of the flat plate 11, and place the outer clamping plate 12 on the flat plate 11. , then slowly turn the flat plate 11 and observe the marking mark m on the stamper P with a microscope. Adjust the stamper slightly with your fingertips so that the rotating marking mark m does not move, and then tighten the screw 13. The stamper P, whose concentricity with the flat plate 11 has been set in this way, is subjected to more accurate centering adjustment at the tip of the spindle shaft shown in FIG. 2, as described above, and then subjected to cutting. If a temporary centering device as shown in FIG. 8 is used, the amount of fine adjustment after attachment to the spindle shaft will be extremely small, and the work can be done quickly and accurately. Such a pre-centering device may be provided on the machine housing 1 shown in FIG. 1 or an extension thereof, or it may be located at a location separate from the machine housing.

Although the apparatus shown in FIG. 1 is a horizontal type, that is, a type in which the axis of rotation is arranged horizontally, the present invention can also be applied to a type that is vertical, that is, a type in which the axis of rotation is arranged vertically. In that case, the cutting tool can be placed above the rotating part, but it is preferable to place the cutting tool below the rotating part in order to protect the stamper from chips.

〔Effect of the invention〕

As explained above, according to the present invention, an inner hole having precision concentricity on the order of 1μ can be easily and reliably formed in a stamper, which is a difficult-to-cut material, and the outer diameter can also be cut with the same precision. Based on this, high-quality optical (laser) disks can be mass-produced. In particular, according to the invention, before starting the cutting operation,
Since the stamper can be cut while carefully and carefully achieving the desired concentricity and checking it, the expensive workpiece stamper is not ruined during the cutting process, and can be compared with conventional methods. It is possible to completely eliminate the troubles during stamper production. Furthermore, according to the present invention, it is possible to precisely inspect whether or not the cutting was performed with the desired concentricity immediately after cutting the inner and outer diameters, ensuring high precision concentricity of the completed stamper. can do.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the stamper precision centering cutting device according to the present invention, and Fig. 2 is a side view showing an embodiment of the stamper precision centering cutting device according to the present invention, and Fig. 2 shows the stamper holder according to the present invention tightening and fixing the stamper to be cut by the outer clamping plate and the flat plate. Figure 3 is an enlarged partial cross-sectional view of the stamper holder that tightens and fixes the stamper to be cut using an inner clamping plate and a flat plate, Figure 4 is a side view of the flat plate of the stamper holder, Fig. 5 is a plan view of the outer clamping plate of the stamper holder, Fig. 6 is a plan view of the inner clamping plate of the stamper holder, and Fig. 7 is a plane view of the stamper to be cut. 8 is a partially sectional side view of a temporary centering device used in combination with the device of FIG. 1. Main symbols, 3...Hollow spindle shaft, 5...Chuck, 5b...Gripping hole, 6...Screw holder,
6a...Through center hole, 7...Fine adjustment screw, 10...
... Stamper holding body, 11 ... Flat plate, 11
a... Shaft portion, 12... Outer tightening plate, 12b... Presser tongue piece, 13... Screw, 14... Inner tightening plate, 14a
... Presser tongue piece, 15 ... Screw, 16 ... Measuring part,
21... Objective lens, 22... Eyepiece lens, 27
...Turret post, 28...Cuttle, 30...Guide block, 31...Guide hole, 35...Microscope, P...
...Stamper to be cut, M...Inner hole.

Claims (1)

[Scope of Claims] 1 (a) A rotatable hollow spindle shaft into which a chuck having a gripping hole is inserted, and a plurality of rotatable hollow spindle shafts that are fixed to the tip of the spindle shaft and whose tips can protrude from the outer periphery to the center through hole. (b) a flat plate having a shaft portion having a smaller diameter than the central through hole and gripped by the gripping hole; a flat plate removably fastened to the flat plate; an outer clamping plate equipped with a plurality of presser tongue pieces extending radially inward to tighten and fix the stamper to be cut while leaving the center region of the stamper, and a center region of the stamper in which an inner hole with desired concentricity is formed. (c) a stamper holder, which is mounted on a pivotable arm parallel to the hollow spindle axis and which is attached to the chuck and the screw holder; (d) a measuring part capable of measuring concentricity of an inner diameter and an outer diameter to be cut on a stamper to be cut on a stamper holder fixed to a stamper holder combined with a screw holder; A stamper precision centering cutting device comprising a cutter supported on a tool post so as to be able to move to a position for cutting the inner and outer diameters of a held stamper. 2 (a) A rotatable hollow spindle shaft into which a chuck having a gripping hole is inserted, and a plurality of fine adjustment screws that are fixed to the tip of the spindle shaft and whose tips can protrude from the outer periphery to the center through hole. (b) a flat plate having a shaft portion having a smaller diameter than the central through hole and gripped by the gripping hole, and a stamper to be cut that is removably fastened to the flat plate and placed on the surface of the flat plate. An outer clamping plate is provided with a plurality of presser tabs extending radially inward to tighten and fix the stamper while leaving its center area, and the center area of the stamper, which has an inner hole of desired concentricity, is tightened and fixed to the flat plate. (c) a stamper holder comprising an inner clamping plate that can be combined with the chuck and screw holder; (d) a guide block having a flat part and equipped with a microscope for pre-measuring the concentricity of the inner hole to be cut of the workpiece stamper placed on the flat plate and performing temporary centering; and (d) the hollow spindle. Measures the concentricity in microns of the inner and outer diameters to be cut on a stamper to be cut, which is mounted on a pivotable arm parallel to the axis and fixed to a stamper holder associated with the chuck and screw holder. (e) a cutting tool supported on a tool rest so as to be movable to a position for cutting the inner diameter and outer diameter of the stamper to be cut, which is held on the stamper holder; Precision centering cutting equipment.