JP2008110464A - Ultrasonic grinding device and grinding wheel used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic grinding device capable of accurately grinding a material to be ground at high speed. <P>SOLUTION: Eight grooves are provided in the peripheral part of a ring-like elastic body 2 made of aluminum, and four fitting holes 24 are provided inside thereof for fitting to a sleeve. The sleeve is a LANGEVIN-type ultrasonic twisted vibrator having tapered holes in a central part thereof so as to be installed in a grinding wheel rotary shaft 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic polishing apparatus that polishes glass, silicon, ceramics, cemented carbide and metal materials using ultrasonic vibration, and a grindstone used for the apparatus.

  In order to polish an object to be polished such as glass, silicon, silicon nitride, rare earth magnet material, super hard metal, and metal material, a polishing apparatus having an annular grindstone is generally used.

  However, for semiconductor materials, magnetic materials, piezoelectric materials, optical materials, and the like, a polished surface with higher accuracy is required. Further, in order to reduce the manufacturing cost of metal materials and the like, it is required to increase the polishing rate.

  In order to satisfy these requirements, it has been proposed to use ultrasonic vibration. The use of ultrasonic vibration for machining has been conventionally performed. For example, a workpiece is cut while applying ultrasonic vibration to a tool such as a tool of a machine tool. Such a cutting method is called ultrasonic cutting, and is described in detail in Non-Patent Document 1. Ultrasonic cutting has the advantages that the frictional resistance between the workpiece and the tool is reduced, so that the thermal distortion of the machined surface is reduced, the machining accuracy is increased, and the life of the cutting tool is extended. ing.

  FIG. 1 is a side view showing a configuration example of a conventional ultrasonic polishing apparatus described in Patent Document 1, and FIG. 2 is a top view taken along line AA shown in FIG. Reference numeral 1 shown in the drawing is a grindstone 1 having an annular shape and having a thickness of 5 to 10 mm and a width of 3 to 8 mm. The grindstone 1 includes diamond abrasive grains and metal bonds or registration bonds. Further, an elastic body 2 is formed on the upper surface of the grindstone 1 with the same diameter and formed of a material that efficiently transmits the displacement of the piezoelectric element, such as bronze, aluminum alloy, duralumin, and stainless steel. It is attached integrally. A cylindrical polishing shaft 3 having a base end connected to driving means is disposed at the center of the upper surface of the elastic body 2, and the elastic body 2 and the grindstone 1 are configured to be movable up and down and in the left-right direction. It is configured to reciprocate.

  An oblong groove is formed on the upper surface of the elastic body 2 in a direction inclined at a certain angle from the normal direction, and a rectangular shape is formed so as to be displaced in a direction inclined at a certain angle at the center of the groove. Each of the laminated piezoelectric actuators 8 is fixedly mounted with an epoxy adhesive. Further, a moisture-proof resin 9 is embedded in the gap between the laminated piezoelectric actuator and the elastic body 2 formed in the oval shape. The laminated piezoelectric actuators 8 are connected in parallel and applied with an alternating voltage by a drive circuit (not shown) so that the elastic body 2 and the grindstone 1 are reciprocated in parallel with the polishing surface. ing.

  On the grinding surface (lower surface) side of the grindstone 1, a work fixing base 5 formed with a larger diameter than the grindstone 1 is disposed. On the upper surface of the work fixing base 5, glass as an object to be polished 7 is stuck and fixed with a hot melt adhesive. In addition, a cylindrical workpiece fixing base shaft 6 connected to the driving means is mounted at the center of the lower surface of the workpiece fixing base 5 so as to polish the workpiece 7 evenly. Are arranged so as to be driven in a state of being deviated by a certain distance. In the upper position of the work fixing base 5, the slurry 4 is jetted onto the workpiece 7 from a pipe connected to the slurry supply means.

According to the above configuration, since the multilayer piezoelectric actuator is used, the apparatus can be manufactured in a small size, a large amplitude is easily obtained even during non-resonance, and almost no heat is generated. Furthermore, it is said that the polishing apparatus can be manufactured at low cost. Further, it can be reduced to about one-third compared with the normal polishing time, and the polished surface can be formed very densely compared with the normal polishing. Furthermore, it is said that rough polishing and precision polishing can be performed by adjusting the applied voltage.
Japanese Patent Laid-Open No. 5-200659 Ultrasonic Handbook Editorial Committee, “Ultrasonic Handbook”, Maruzen Co., Ltd., August 1999, p679-684

  However, the configuration of Patent Document 1 uses a laminated piezoelectric actuator that easily obtains a large amplitude of several tens of microns or less even when non-resonant at 1 KHz or less, but the piezoelectric material used for this has a mechanical quality. Since a so-called LQ material having a small coefficient is used, the heat generation at the time of resonance in the ultrasonic region is very large, and the polarization of the piezoelectric material may disappear. If the polarization disappears, it will no longer act as a vibration source. Furthermore, the machined surface accuracy also decreases.

  In addition, even with a laminated piezoelectric actuator, it is very possible to give a vibration of 1 micron or more to the grindstone 1 and the elastic body 2 having a size such that the diameter of the grindstone 1 exceeds 0.1 m by non-resonance in an ultrasonic region of 15 KHz or more. Have difficulty.

  An object of the present invention is to provide a polishing apparatus that realizes excellent polishing surface accuracy and polishing speed.

  According to the present invention, in an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, an ultrasonic torsional vibrator is used, and an elastic body to which a grindstone is bonded has a slit.

  The present invention also provides an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, in which an ultrasonic torsional vibrator is bonded to an elastic body to which a grindstone is bonded, and the elastic body to which the grindstone is bonded has a slit. .

  Another object of the present invention is to use an ultrasonic torsional vibrator in an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, and to have a slit in a rotating disk.

  Since the ultrasonic polishing apparatus of the present invention employs the torsional vibration mode, it can increase the acceleration in the circumferential direction. Furthermore, since a part of torsional vibration can be converted into radial vibration by the slit, radial acceleration can also be increased. For this reason, the ultrasonic polishing apparatus of the present invention can increase the polishing surface accuracy and the polishing rate.

  The ultrasonic polishing apparatus of the present invention can also obtain a desired magnitude of vibration with a small electric power. Therefore, not only power saving, but also the increase in the temperature of the grindstone can be reduced, so that the accuracy of the polished surface can be increased.

  Further, the ultrasonic polishing apparatus of the present invention greatly reduces the consumption of the grindstone, which helps to save resources and reduce manufacturing costs.

  The ultrasonic polishing apparatus according to the first embodiment of the present invention will be described with reference to the side view of FIG. There is a processing table rotating shaft 11 for rotating the processing table 10. The processing table rotating shaft 11 is connected to a motor (not shown). On the processing table, for example, a lithium niobate substrate, which is the object 7 to be polished, is bonded onto a steel disk using hot melt wax.

  The sleeve 27 constituted by the ultrasonic torsional vibrator 25 is attached to the grindstone rotating shaft 18 by a bolt 28a. Then, the annular elastic body 2 that joins the grindstone 1 and has the slit 26 is joined to the ultrasonic torsional vibrator 25 that is the sleeve 27 by the bolt 28b. A rotary rotary transformer 15a is connected to the upper part of the ultrasonic torsional vibrator 25 by a bolt (not shown). The case 21 at the opposite position has a fixed-side rotary transformer 15b. An ultrasonic oscillator 17 is connected to the fixed-side rotary transformer 15 b by a lead wire 16.

  The details of the rotary transformer 15a on the rotation side and the rotary transformer 15b on the fixed side will be described with reference to FIG. 4 (A) and a front view of FIG. 4 (B). The rotary rotary transformer 15a in which the coil 23 is arranged on the ferrite 22 which is a soft magnetic material is opposed to the fixed rotary transformer 15b, and ultrasonic AC power is transmitted from the fixed rotary transformer 15b to the rotary rotary transformer 15a. To do. The grindstone rotating shaft 18 is connected to a motor (not shown).

  Further, the slurry 4 is disposed above the processing table 10 so that the slurry 4 is ejected from the slurry tank 19 through the pipe 20.

  3 and FIG. 4, the details of the elastic torsional vibrator 25, which is the elastic body 2 having the slit 26 and the sleeve 27, are joined to the grindstone 1 used in FIG. 3 and FIG. 5, and a line AA in FIG. This will be described with reference to FIG. Moreover, the structure which joined the grindstone 1 and the elastic body 2 is called by names, such as a cup grindstone or a grinding wheel.

  Eight grooves are provided in the outer peripheral portion of the ring-shaped elastic body 2 made of aluminum, and four attachment holes 24 are provided inside. The four attachment holes 24 are for attachment to the sleeve 27. The sleeve 27 is a Langevin type ultrasonic torsional vibrator 25 having a tapered hole for attaching to the grindstone rotating shaft 18 at the center. The Langevin type ultrasonic torsional vibrator 25 is configured by sandwiching piezoelectric ceramics 12a and 12b between elastic bodies 2a and 2b made of aluminum alloy and fastening them with bolts 28a.

Details of the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25 will be described with reference to the perspective view of FIG. The arrow direction in FIG. 7 indicates the polarization direction. When an AC electric field is applied perpendicularly to the polarization direction, it vibrates in the same arrow direction as the polarization direction. The torsional vibrator is described in detail in Non-Patent Document 1.
Yoshiro Tomikawa, “Ultrasonic Electronics Vibration Theory”, Asakura Shoten Co., Ltd., February 1998, p113-122

  Next, an operation method of the ultrasonic polishing apparatus will be described with reference to FIG. First, a steel disk having a lithium niobate substrate bonded to the processing table 10 is adsorbed by electromagnetic force. Then, the position of the grindstone 1 is adjusted by an adjusting device (not shown) so as to be an appropriate position. Next, the motor is activated to rotate the machining table 10. At the same time, the slurry 4 is ejected from the slurry tank 19 through the pipe 20. Then, the ultrasonic oscillator 17 is turned on, and an ultrasonic alternating voltage is applied to the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25 through the fixed rotary transformer 15b and the rotary rotary transformer 15a. Next, the motor is turned on and the grindstone 1 is rotated to polish the lithium niobate substrate.

  Here, the vibration of the elastic body 2 when an ultrasonic alternating voltage is applied to the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25 will be described. When an ultrasonic alternating voltage is applied to the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25, the elastic body vibrates as indicated by a two-dot chain line in FIG. Here, the vibration displacement indicated by a two-dot chain line is illustrated larger than the actual displacement for easy illustration. The ultrasonic torsional vibrator 25 vibrates torsionally. The torsional vibration propagates to the elastic body 2 attached to the ultrasonic torsional vibrator 25 by the bolt 28b, and a part of the torsional vibration is converted into expansion / contraction vibration by the slit 26 provided in the elastic body 2. The surface accuracy of the polished surface is improved by simultaneously exciting torsional vibration and expansion / contraction vibration parallel to the polished surface. And since the frictional resistance with the object 7 to be processed is reduced due to the effect of ultrasonic vibration, the thermal distortion of the processed surface is reduced, the processing accuracy is increased, and the life of the grindstone is extended. Has advantages.

  In addition, since only the elastic body 2 to which the grindstone 1 is bonded and the ultrasonic torsional vibrator 25 attached to the tip of the grindstone rotating shaft 18 are substantially ultrasonically vibrated, ultrasonic vibration is hardly transmitted to the grindstone rotating shaft 18 or the like. Therefore, ultrasonic vibration can be applied to the grindstone 1 efficiently and stably.

  Further, since the ultrasonic polishing apparatus of the present invention applies the ultrasonic alternating voltage using the rotary transformer 15 joined to the ultrasonic torsional vibrator 25, the ultrasonic alternating voltage can be applied even at a high rotational speed. Therefore, the polishing rate can be improved.

  In the ultrasonic polishing apparatus of the present invention, since only the slit 26 is provided on the elastic body 2 to which a commercially available grindstone is bonded, a conventional product can be used. Therefore, it is possible to provide a grindstone that imparts ultrasonic vibration at a low cost.

  A second embodiment of the present invention will be described. Since the same ultrasonic polishing apparatus as in the first embodiment is used, only the configuration in which the grindstone 1 is joined to the elastic body 2 and the ultrasonic torsional vibrator 25 will be described.

  Details of the grindstone 1 and the like of the second embodiment will be described with reference to a plan view in FIG. 9 and FIG. 10 which is a cross-sectional view taken along the line AA in FIG.

  Eight slits 26 are provided in the ring-shaped elastic body 2 made of aluminum, and the eight piezoelectric ceramics 12 are joined using an epoxy adhesive. The piezoelectric ceramic 12 has a waterproof coating applied on its surface. The eight piezoelectric ceramics 12 operate as ultrasonic transducers. Further, four attachment holes 24 are provided in the elastic body 2. These four attachment holes 24 are for attachment to the sleeve.

  The piezoelectric ceramic 12 used here is the same as that shown in FIG. 7, and is polarized in the circumferential direction as shown by the arrows.

  As in the first embodiment, when an ultrasonic alternating voltage is applied to the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25, the elastic body vibrates as indicated by a two-dot chain line in FIG. The ultrasonic torsional vibrator 25 vibrates torsionally. The torsional vibration propagates to the elastic body, and a part of the torsional vibration is converted into expansion / contraction vibration by the slit 26 provided in the elastic body. By simultaneously exciting torsional vibration and expansion / contraction vibration parallel to the polishing surface, the surface accuracy and polishing speed of the polishing surface are improved. And since the frictional resistance with the object 7 to be processed is reduced due to the effect of ultrasonic vibration, the thermal distortion of the processed surface is reduced, the processing accuracy is increased, and the life of the grindstone is extended. Has advantages.

  A third embodiment of the present invention will be described. Since the same ultrasonic polishing apparatus as that of the first embodiment is used, only the elastic body 2 to which the grindstone 1 is bonded, the rotating disk having the slit 26 and the Langevin type ultrasonic torsional vibrator 25 will be described.

  Details of the grindstone 1 and the like of the third embodiment will be described with reference to the plan view of FIG. 11 and FIG. 12 which is a cross-sectional view taken along the line AA of FIG.

  The aluminum ring-shaped elastic body 2 to which the grindstone is bonded is attached to an aluminum alloy rotating disc 14 provided with eight slits 26 attached to the grindstone rotating shaft 18 by bolts using bolts (not shown). A Langevin type ultrasonic torsional vibrator 25 is joined to the upper part of the grindstone rotating shaft 18 with a bolt (not shown). The Langevin type ultrasonic torsional vibrator 25 is configured by sandwiching piezoelectric ceramics 12a and 12b between elastic bodies 2a and 2b made of aluminum alloy and fastening them with bolts (not shown). Further, a rotary transformer 15a on the rotating side is connected to the upper portion of the ultrasonic torsional vibrator 25 by a bolt (not shown). And there is a fixed-side rotary transformer 15b at the opposite position. An ultrasonic oscillator 17 is connected to the fixed-side rotary transformer 15 b by a lead wire 16.

  The piezoelectric ceramic 12 used here is the same as that shown in FIG. 7, and is polarized in the circumferential direction as shown by the arrows.

  As in the first embodiment, when an ultrasonic alternating voltage is applied to the piezoelectric ceramic 12 of the ultrasonic torsional vibrator 25, the elastic body vibrates as indicated by a two-dot chain line in FIG. The ultrasonic torsional vibrator 25 vibrates torsionally. The torsional vibration propagates through the grindstone rotating shaft 18 and further propagates to the rotating disk 14, and a part of the torsional vibration is converted into expansion / contraction vibration by the slit 26 provided in the rotating disk 14. By simultaneously exciting torsional vibration and expansion / contraction vibration parallel to the polishing surface, the surface accuracy and polishing speed of the polishing surface are improved. And because of the effect of ultrasonic vibration, the frictional resistance with the workpiece to be processed is reduced, so that the thermal distortion of the processed surface is reduced, the processing accuracy is increased, and the life of the grindstone is extended. have.

  In the above description, a cup grindstone and a grinding wheel are used, but it is of course applicable to those having other rotating grindstones.

  The ultrasonic polishing apparatus of the present invention is used for polishing an object to be polished such as glass, silicon, silicon nitride, rare earth magnet material, and metal material.

It is a side view which shows the structural example of the conventional ultrasonic polishing apparatus. It is a top view from the AA line shown in FIG. It is a side view which shows the structural example of the ultrasonic polishing apparatus of the 1st Embodiment of this invention. It is the top view and side sectional drawing which show the rotary transformer used for FIG. FIG. 4 is a plan view showing details of the grindstone, elastic body, ultrasonic torsional vibrator, and the like of FIG. 3. It is sectional drawing cut | disconnected by the AA line of FIG. It is a perspective view which shows the piezoelectric ceramic used for the ultrasonic torsional vibrator. It is a figure explaining the torsional vibration and expansion / contraction vibration excited by the elastic body. It is a top view which shows details, such as a grindstone of the 2nd Embodiment of this invention, an elastic body, and an ultrasonic torsion vibrator. It is sectional drawing cut | disconnected by the AA line of FIG. It is a top view which shows details, such as a grindstone of the 2nd Embodiment of this invention, an elastic body, and an ultrasonic torsion vibrator. It is sectional drawing cut | disconnected by the AA line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grinding wheel 2 Elastic body 3 Polishing shaft 4 Slurry 5 Work fixing base 6 Work fixing base shaft 7 Workpiece 8 Laminated piezoelectric actuator 9 Moisture-proof resin 10 Processing table 11 Processing table rotating shaft 12 Piezoelectric ceramic 13 Groove 14 Rotating disk 15 Rotary transformer 16 Word line 17 Ultrasonic oscillator 18 Grinding wheel rotating shaft 19 Slurry tank 20 Pipe 21 Case 22 Ferrite 23 Coil 24 Mounting hole 25 Ultrasonic torsional vibrator 26 Slit 27 Sleeve 28 Bolt

Claims (3)

  In an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, an ultrasonic torsional vibrator is used, and an elastic body to which a grindstone is bonded has a slit.   In an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, an ultrasonic torsional vibrator is bonded to an elastic body to which a grindstone is bonded, and the elastic body to which the grindstone is bonded has a slit. .   In an ultrasonic polishing apparatus that performs polishing using ultrasonic vibration, an ultrasonic torsional vibrator is used, and a rotating disk has a slit.

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