JP2719334B2 - Disk centering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk centering device used in an optical disk master cutting device or the like. 2. Description of the Related Art When performing high-precision cutting on a disk, such as when performing cutting on an optical disk master, a device that accurately matches a disk sensor with a spindle sensor, that is, a centering device is used. Some disk centering devices are based on the outer diameter of the disk, while others are based on the inner diameter. In the apparatus based on the outer diameter of the disk, the deflection of the outer diameter is detected by an appropriate sensor, and the position adjusting device of the disk is controlled based on the detection result. On the other hand, in the case of using the inner diameter as a reference, a screw having a cylindrical portion for centering is screwed into the center of the disk fixing plate so that the cylindrical portion matches the inner periphery of the center hole of the disk. [Problems to be Solved by the Invention] As described above, since the centering device based on the outer diameter has a sensor and a position adjusting device on the outer peripheral portion of the disk, if the outer diameter of the disk is constant, Although there is no problem, in reality there are various outer diameters in the range of about φ90 to φ360,
There are problems that cannot be addressed in all of them. In addition, when the optical head for cutting is moved to the center of the disc, the centering cylindrical portion protrudes at the center of the disc.
There is a problem of interference with the centering column. Therefore, the present invention relates to a centering device based on the inner diameter, which is advantageous in that the size of the disk is not limited.
An object of the present invention is to provide a centering device that does not cause interference with a cutting optical head. [Means for Solving the Problems] In order to solve the above problems, the present invention provides a centering unit mounting hole at the center of a disk fixing plate mounted on the upper end of a spindle, and The centering unit mounted in the hole includes a unit body fixed in the hole, a split collet protruding from the unit body, and a collet expanding device inserted into the split collet. The center of the collet is aligned with the center of the spindle, the upper end of the split collet is protruded from the disc fixing plate by the height of the thickness of the disc, and the outer diameter of the protruding portion of the split collet is smaller than the inner diameter of the disc. And setting the upper end of the collet expanding device to a height lower than the upper end of the split collet,
The split collet is expanded by the collet expanding device so that the outer periphery of the split collet coincides with the inner circumference of the disk on the disk fixing plate to perform centering of the disk. [Function] After the center hole of the disk is fitted on the outer peripheral surface of the upper end of the split collet and placed on the disk fixing plate, the collet expanding device is operated to expand the split collet. The center of the disc is aligned with the center of the spindle by matching the inner peripheral surface of the center hole. Embodiment FIG. 1 and FIG. 2 show a part of a cutting device provided with a disk centering device of this embodiment.
The cutting device has an air spindle 2 supported on a base 1, and a disk centering device 3 of the present invention is detachably attached to the upper end of the air spindle 2 by bolts 4. The disk centering device 3 has a disk fixing plate 5 mounted on the air spindle 2 by the bolts 4 described above. The disk fixing plate 5 has a centering unit device hole 6 formed in the center. A recess 7 is formed at the bottom of the mounting hole 6, that is, at the center of the upper end surface of the air spindle 2, and an air passage 8 is formed at the center of the recess 7. Unit body 9 attached to the bottom of mounting hole 6
Is a cylinder part which is inserted into the recess 7 on its lower surface.
10 is provided, and a split collet 11 protrudes from the upper surface. The split collet 11 is formed by arranging six resilient collet pieces 12 at a base portion in a ring at a predetermined interval (see FIG. 3), and is configured as a cylindrical shape as a whole. It coincides with the center of the air spindle 2. The upper end of the split collet 11 protrudes from the upper end of the disk fixing plate 5 by the height of the thickness of the disk a (about 1.2 to 10 mm). The outer diameter of the upper end of the split collet 11 is slightly smaller than the inner diameter of the center hole of the disk a in a normal state. On the inner peripheral surface of the split collet 11, a lower portion is formed as a small-diameter tapered surface 13, into which a collet expanding device 14 is inserted. The collet expanding device 14 includes a sphere 15 having a diameter that comes into contact with the tapered surface 13, a piston rod 16 that moves the sphere 15 up and down, and a coil spring that applies an upward urging force to the sphere 15 and the piston rod 16. Consists of 17. The above piston rod 16 penetrates the sphere 15,
A nut 18 is screwed onto the upper end to prevent the spherical body 15 from coming off. The height of the upper end surface of the nut 18 is set lower than the upper end of the collet piece 12. The piston rod 16 slidably penetrates the unit body 9 and is integrated with an air piston 19 inserted into the cylinder section 10 of the unit body 9. Also,
A piston rod 16 ′ also extends to the lower surface of the air piston 19, and the piston rod 16 ′ is slidably inserted into the air passage 8 of the air spindle 2 while maintaining airtightness. An air hole 20 is formed at the center of the piston rod 16 ′ and the piston 19, and pressurized air is introduced into the cylinder portion 10. In addition, in the figure, 21 is a mounting bolt of the unit body 9, 22 is an air passage for fixing the disk a, and 23 is a stopper of the piston 19. The centering device according to the embodiment of the present invention is configured as described above, and its operation will be described next. The center hole 24 of the disc a to be cut is fitted on the outer periphery of the upper end of the collet 11, and the disc a is placed on the fixing plate 5. Thereafter, when pressure air is supplied to the air passage 8 to increase the internal pressure of the cylinder portion 10, the piston 19 is lowered, and at the same time, the sphere 15 is lowered by the piston rod 16. When the sphere 15 is lowered, each collet piece 12 of the split collet 11 is inclined outward and expanded.
Since the center of the split collet 11 coincides with the center of the air spindle 2, if the contact position between the sphere 15 and the inner surface of each collet piece 12 and the thickness of the upper end portion are made uniform, Also, the center of the outer diameter of the split collet 11 coincides with the center of the air spindle 2. Therefore, the outer peripheral surface of the split collet 11 is
The center of the disc a can be centered by matching the inner circumference of the center hole 24 of FIG. According to experiments, an accuracy within 10 μm was obtained. After the centering, air is sucked from the air passage 22 to fix the disk a. The outer diameter of the disk a is 90 to 360
There are various types with φ, inner diameter of 10φ to 65φ and thickness of 1.2 to 10mm. For the difference in size, the disk fixing plate 5 and the centering unit (unit body 9, split collet 11 and It can respond freely by changing the combination with the expanding device 14). [Effect of the Invention] As described above, the present invention uses a centering unit formed by a combination of a split collet and its expanding device,
Centering can be performed with reference to the inner diameter of the disk, and since there is no portion protruding above the disk, there is no hindrance to cutting near the center of the disk. Also, 1.2m
Centering in the case of a thin disk of about m is also possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a part of a cutting device, FIG. 2 is a sectional view of an embodiment of a centering device, and FIG. 3 is a sectional view taken along a line II-III. DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Air spindle, 3 ... Disk centering device, 5 ... Disk fixing plate, 6 ... Centering unit device hole, 8 ... Air passage, 9 ... Unit body,
10 ... Cylinder part, 11 ... Split collet, 13 ... Tapered surface, 14 ... Expansion device, 15 ... Spherical body, 16 ... Piston rod, 17 ... Coil spring, 19 ... Air piston, 20 ... … Air holes.

Claims (1)

(57) [Claims] A centering unit mounting hole is provided in the center of the disk fixing plate attached to the upper end of the spindle, and the centering unit mounted in the centering unit mounting hole is protruded from the unit body fixed in the hole and the unit body. The center of the split collet is made to coincide with the center of the spindle, and the upper end of the split collet is moved from the disk fixing plate to the center of the disk. Projecting by the height of the thickness, and forming the outer diameter of the protruding portion of the split collet smaller than the inner diameter of the disk, setting the upper end of the collet expanding device to a height lower than the upper end of the split collet, The split collet is expanded by a collet expanding device, and the outer circumference of the split collet is moved to the inner circumference of the disk on the disk fixing plate. Disc centering apparatus that is matched performs centering of the disk.