JP4783719B2 - Finishing method and finishing apparatus using fluid in which dielectric abrasive grains are dispersed in water under electric field - Google Patents

Description

  The present invention relates to a finishing method and a finishing apparatus using a fluid in which dielectric abrasive grains in an electric field used for brittle materials such as glass used in IT and the medical equipment industry are dispersed in water.

  Grinding using an existing grindstone is known as a rational processing method as a method of applying a shape to a brittle material sample such as glass, quartz, silicon wafer, and sapphire. This method has a drawback that fine scratch marks are generated. Although a method using loose abrasive grains in which abrasive grains are dispersed in a slurry is known, it is known that time is required for finishing, that is, processing efficiency is low.

In recent years, in surface finishing methods, as a method of processing while applying an electric field, it is characterized by a mechanism that sharpens the grinding wheel by melting the metal bond material that fixes the abrasive grains of the fixed grinding stone by applying an electric current. An ELID grinding method (Erid grinding method) has also been reported, and as an effect thereof, it is attracting attention as a high-precision and high-efficiency grinding method by preventing clogging of the grindstone and exposing a fresh cutting edge to the grindstone at any time.
However, even with this method, it is known that scratch marks due to the abrasive grains of the grindstone remain in the tough sample.

  Then, the grinding | polishing method using the existing loose abrasive grain is recognized again. For example, in the method (apparatus) shown in FIG. 7, a pad 73 is attached to the opposing surfaces of the rotating upper and lower surface plates 71, 72, the opposing interval is set to about 6 mm, and the workpiece (2 mm thick) facing this opposing interval ( Glass etc.) 74 is intended to be polished and a temporary polishing effect was seen. In the figure, reference numeral 75 denotes a planet carrier for fitting and holding a workpiece.

However, in the method shown in FIG. 7, when loose abrasive grains (slurry) are used, the abrasive grains are scattered from the polishing region to the outside by the centrifugal force generated by the polishing surface plate, and the processing pressure is reduced to the workpiece ( Because it is applied to glass, etc., loose abrasive grains (slurry) do not easily enter the center of the workpiece, and the outer edge of the sample is greatly shaved, so that the center of the workpiece is hard to flow into the center of the workpiece. Had the problem of long finishing time. As described above, it has been known that the method has a low processing efficiency.
Therefore, it has been desired to create a new apparatus and processing method that can solve the conventional problems and realize an excellent polishing effect.

The present invention has been proposed in view of the above circumstances, and an insulating polishing pad is attached to the lower surface of the electrode plate to form an upper surface plate, and an insulating polishing pad is attached to the upper surface of the electrode plate to form a lower surface plate. Each of the surface plates can be rotated in a state where the respective insulating polishing pads are opposed to each other, and a work piece fitted to a rotatable planet carrier is exposed to the facing interval, and dielectric abrasive grains are further applied to water. The dispersed slurry is supplied, and an electric field of a repetitive square wave with a good rise at a low frequency in which the water in the slurry is sensitive is applied, and each surface plate and planet carrier are rotated at different speeds or in opposite directions. Thus, the surface of the workpiece is finished to a high quality with a better polishing efficiency, and a process using a fluid in which dielectric abrasive grains are dispersed in water under an electric field. It relates under way.

  Further, the present invention provides the above finishing method, wherein an electrode plate in which conductors and insulators are alternately arranged is fixed to the lower surface of the insulating plate, and an insulating polishing pad is attached to the lower surface to form an upper surface plate. Dispersing dielectric abrasive grains in water under an electric field characterized in that an electrode plate with alternating conductors and insulators is fixed on the upper surface, and an insulating polishing pad is attached on the upper surface to form a lower surface plate A finishing method using fluid is also proposed.

Further, the present invention provides an upper surface plate with an insulating polishing pad attached to the lower surface of the electrode plate, and a lower surface plate with an insulating polishing pad attached to the upper surface of the electrode plate. A supply mechanism for allowing a polishing pad to be rotated in a state of being opposed to each other, supplying a slurry in which dielectric abrasive grains are dispersed in water so that a workpiece fitted on a rotatable planetary carrier faces the interval between the polishing pads. And a control mechanism capable of controlling electric field application and non-application intervals with a repetitive square wave electric field with a favorable rise in low frequency sensitive to water in the slurry, and each of the surface plate and the planet carrier. in which also proposes the finishing apparatus using a dielectric abrasive grains in an electric field, characterized in that it comprises a rotation mechanism for rotating at different speeds or reverse dispersed in water fluid
In addition, although the water to be used may vary depending on the abrasive grains, alkaline electroreduction water or acidic oxidized water that is easy to react with the work material by forcibly applying an electric field may be used.

  Further, the present invention provides the finishing apparatus, wherein an electrode plate in which conductors and insulators are alternately arranged is fixed to the lower surface of the insulating plate, and an insulating polishing pad is attached to the lower surface to form an upper surface plate. Dispersing dielectric abrasive grains in water under an electric field characterized in that an electrode plate with alternating conductors and insulators is fixed on the upper surface, and an insulating polishing pad is attached on the upper surface to form a lower surface plate A finishing device using fluid is also proposed.

Furthermore, the present invention provides a finishing device using a fluid in which dielectric abrasive grains under electric field are dispersed in water , wherein the conductor and the insulator are concentrically arranged in the finishing device. suggest.

According to the present invention, in the finishing device, dielectric abrasive grains under an electric field are dispersed in water , wherein a plurality of conductors and insulators arranged in a small ring are arranged on one rotating surface. We also propose a finishing device that uses the fluid .

  In the finishing method of the present invention, a relative speed is given to the slurry, and the slurry is easily discharged by the centrifugal force of the rotation of the surface plate. However, since the dielectrophoretic force acts from the upper and lower electrodes, the slurry is scattered. Can be suppressed. Therefore, it can be suitably used for finishing processing of brittle materials such as glass used in the IT and medical equipment industries.

  The finishing apparatus of the present invention can obtain a reasonable polishing effect by the polishing assistance effect by the mechanochemical phenomenon and the polishing phenomenon by the abrasive grains, and positively has a current of about 0.1 to 5 A in water. The finishing method in which ions are actively implanted and ions are actively implanted can be implemented.

  In particular, when the electrode plate is configured by alternately arranging conductors and insulators, if a positive electric field acts on water with a high dielectric constant, the attractive force gathers at the electrode end that generates a positive electric field by positive dielectrophoresis Therefore, the slurry spreads over the insulating portion surface and is disposed on the surface of the workpiece. As a result, the front and back surfaces of the workpiece can be smoothly finished, and the scattering of the slurry can be suppressed.

  Further, when the conductor and the insulator are arranged concentrically, the distance between the electrodes can be shortened and the electric field strength can be maintained high.

  Also, when a plurality of conductors and insulators arranged in a small ring are arranged on one rotating surface, a brush of abrasive grains is formed in the direction in which the material to be polished is rotated and the polishing debris is discharged well. Will be.

In the finishing method and the finishing apparatus of the present invention, there are a case where the electrode plate is constituted by a single conductor and a case where the conductor and the insulator are alternately arranged to form the electrode plate.
First, when the electrode plate is constituted by a single conductor, an insulating polishing pad 13 is attached to the lower surface of the electrode plate 11 as shown in FIG. Further, an insulating polishing pad 13 was attached to the upper surface of the electrode plate 12 to form a lower surface plate. And the insulating polishing pads 13 and 13 of each surface plate were made to oppose, and it was made possible to rotate in this state. In addition, the workpiece 14 fitted to the rotatable planetary carrier 15 is faced at the facing interval, and a slurry 16 in which abrasive grains are dispersed in water is supplied.

  In order to compare with the existing polishing method using free abrasive grains (FIG. 7), the cross-sectional configuration is similar, but the difference from the present invention is that the surface plate is provided with an electrode plate and water is sensitive. Since the point where a square wave electric field is repeatedly applied at a low frequency in the plus region and the point where a slurry in which abrasive grains are dispersed in water are used as the slurry are different, these configurations will be described in detail below.

  As the electrode plates 11 and 12, cast iron disks were used, but there is no particular limitation as long as they are conductors. The insulating polishing pad 13 is an insulating polishing pad made of polyurethane or pre-kneaded with cerium oxide or the like. The upper surface plate and the lower surface plate each include a rotation mechanism and a control mechanism (not shown) that can rotate at different speeds or directions. The planet carrier 15 has a convex portion continuous on the outer periphery, a plurality of planet carriers 15 are supported on a large-diameter support plate (not shown), and a concave portion that meshes with the convex portion of the planet carrier 15 is provided on the rotation shaft. And can be rotated. Further, the planet carrier 15 is provided with an opening, and with the workpiece 14 held in the opening, the workpiece 14 and the planet carrier 15 are different in speed or direction from the upper surface plate and the lower surface plate. Can be rotated.

As the slurry 16, a slurry in which dielectric abrasive grains are dispersed in water is used.
The inventors of the present invention have so far conducted research using a fluid in which abrasive grains are dispersed in silicone oil, but in consideration of the environment, water having high affinity with glass was used. Silicone oil has a dielectric constant of about 3, but water has a high dielectric constant of 80, so that a mechanochemical effect is expected to improve polishing efficiency. That is, by using a slurry in which water and abrasive grains are mixed for polishing, it is expected that a reasonable polishing effect can be obtained by the polishing assistance effect by the mechanochemical phenomenon and the polishing phenomenon by the abrasive grains. In addition, the slurry containing abrasive grains is dominated by water having a high dielectric constant by using an electric field, and it is expected that the water itself suppresses scattering of the abrasive grains. When silicone oil is used in place of the slurry water, it contains the same component Si as the glass, so that the silicon oil Si adheres to the glass and scattering of the abrasive grains is suppressed, but the polishing efficiency decreases. .
As the dielectric abrasive grains, those having a hardness equal to or higher than the hardness of the workpiece or having a mechanochemical action with the workpiece are used. Specifically, diamond, corundum, emery, garnet, silica, calcined dolomite, fused alumina, artificial emery, silicon carbide, zirconium oxide, etc., or chromium oxide, silicon oxide, iron oxide, calcium oxide used for mechanochemical polishing , Magnesium oxide, cerium oxide, magnesium carbide, barium carbonate and the like.

  The finishing method of FIG. 1 can perform a finishing process far superior to that of the method of FIG. 7, and has a polishing efficiency of 1.5 times or more as shown in Example 1 described later. The improvement effect was able to be acquired.

  However, in the method of FIG. 1, for example, when the thickness of the workpiece increases, the distance between the electrodes also changes accordingly, and it is necessary to supply a high voltage in order to give effective abrasive grain arrangement characteristics to the slurry. there were. In such a case, as shown in FIGS. 2 and 3, the conductors 21 and the insulators 22 may be alternately arranged to form an electrode plate.

When an electrode plate is formed by alternately arranging conductors and insulators, an insulator 22 is sandwiched between two conductive wires 21 with insulation coating as shown in FIG. 2, and the electrodes are wound in a circle as shown in FIG. Constitute. Then, as shown in FIG. 3, the insulating layer 33 and the electrode plate having the above-described configuration were formed on the lower surface of the upper surface plate 31 and the upper surface of the lower surface plate 32, respectively, and the insulating polishing pad 34 was attached to the outside thereof. Then, the insulating polishing pads 34 and 34 of each surface plate are made to face each other and can be rotated in this state. In addition, a workpiece 36 fitted on a rotatable planet carrier 35 is faced to the facing interval, and a slurry 37 in which dielectric abrasive grains are dispersed in water is supplied.
Each configuration is the same as that of the finishing apparatus of FIG. 1. Specifically, the insulating polishing pad 34 is the same as the insulating polishing pad 13, and a rotating mechanism and a control mechanism are provided on the upper surface plate and the lower surface plate. The same is true for the planet carrier 35, and the planet carrier 15 is the same as the planet carrier 15.

  And it is good also as a structure shown in FIG. 4 by arranging the conductor 21 and the insulator 22 alternately and concentrically, or arranging the conductor 21 and the insulator 22 alternately and arranging them in a small ring shape. A plurality (8 in the drawing) may be arranged on one large-diameter rotating surface, and the configuration shown in FIG.

  In this finishing apparatus, by applying an electrophoretic force (Coulomb force), the slurry 37 containing the dielectric abrasive grains gathers in a place where polishing is required as shown in the figure, and it is easy to provide a processing pressure to the abrasive grains. Furthermore, it is possible to finish smoothly by providing a relative speed so that the abrasive grains roll.

  As described above, in a finishing apparatus in which conductors and insulators are alternately arranged to form an electrode plate, slurry in which dielectric abrasive grains are dispersed gathers on the insulator of the electrode, and the abrasive grains are supplied to the workpiece surface. . Therefore, the scattering property of abrasive grains that normally scatter due to the centrifugal force generated by the rotation of the polishing apparatus is suppressed. That is, it is possible to provide a reasonable finishing technique because it is easy to supply the processing pressure through the abrasive grains applied to the workpiece, and the mechanical chemical reaction action of the workpiece and the slurry is combined.

  In addition, when the thickness of the conductors and insulators that supply these electric fields is increased and the width of the electrode area is increased, the capacitor characteristics become remarkable, and the electric field applied by the abrasive grains on the end face of the electrode surface is suppressed by the leaking electric field. Is done. This makes it difficult to hold the slurry used for polishing. Therefore, the electric field leaking to the electrode surface increases by narrowing the width so as to reduce the electrode area and by narrowing the width. As a result, the arrangement of the abrasive grains can be controlled.

  The electric field of the repetitive square wave at the low frequency in the positive range to which water is sensitive is represented in the graph shown in FIG. The electric field for attracting the water-based fluid with the electric field is applied positively as shown. However, excessive charging is prevented by applying a negative value.

In the finishing apparatus shown in FIG. 1, the rotating upper and lower surface plates 11 and 12 are used as electrodes, the insulating polishing pads 13 and 13 having a thickness of 2 mm are attached to the opposing surfaces, and the workpiece 14 has a thickness of 2 mm. The counter electrode interval is about 6 mm, and in order to polish the workpiece (glass) 14 facing the counter interval, a slurry 16 in which dielectric abrasive grains such as cerium oxide particles are dispersed in water is supplied, An electric field supply condition of a supply electric field of 2.0 kV, 0.8 Hz, and an offset of 0.5 kV was given as a positive low frequency repetitive square wave electric field to which water in the slurry 16 is sensitive.
As a result, the polishing efficiency was improved by about 1.5 times compared to the existing polishing method (FIG. 7) in which no electric field was applied.

FIGS. 2 and 3 are embodiments in which conductors 21 and insulators 22 are alternately arranged to constitute an electrode plate, and the conductors 21 and the insulators 22 are arranged concentrically. In the perspective view of FIG. 2, the insulator 22 is sandwiched between two conductors 21 that are insulated and covered.
The upper surface plate 31 shown in FIG. 3 is formed by fixing an electrode plate in which conductors 21 and insulators 22 are alternately arranged on the lower surface of an insulating layer 33 and attaching an insulating polishing pad 34 to the lower surface.
The lower surface plate 32 is formed by fixing an electrode plate on which the conductors 21 and the insulators 22 are alternately arranged on the upper surface of the insulating layer 33 and attaching an insulating polishing pad 34 on the upper surface thereof.
The surface plates 31 and 32 can be rotated with their insulating polishing pads 34 and 34 facing each other, and may be rotated at different speeds in the same direction or in opposite directions. May be.

FIG. 4 shows a configuration in which conductors 21 and insulators 22 are alternately arranged and arranged concentrically, and FIG. 5 also shows conductors 21 and insulators 22 arranged alternately and arranged in a small ring shape. A plurality (8 in the drawing) are arranged on one large-diameter rotating surface.
In any example, the cross-sectional structure at the cut surface shown in the figure has the cross-sectional structure shown in FIG. 3 and can be operated as described above.

[Example 1]
In the finishing apparatus of FIG. 1, as the slurry 16 supplied to the facing interval, a slurry in which 20 to 30 wt% of cerium oxide is dispersed in water was used. The shape of the workpiece 14 was 40 mm square, a thickness of 2 mm, and a normal glass BK-7 was used.
As the supply electric field, the waveform is a repetitive square wave, and the AC electric field strength is 0.1 to 2 kV / mm plus, the minus side is 0.025 to 0.5 kV / mm, and the frequency is 0.1 to 20 Hz. Feed conditions were given. Further, in consideration of improvement of the processing waste discharging performance, an electric field supply time is provided at the time of electric field supply. In other words, by providing a time during which no electric field is applied, the fluid retention time is reduced, and the exclusion of processing waste is promoted.
A ground glass workpiece 14 having a surface roughness of Ra 0.25 μm before polishing was finished to Ra 0.010 μm after polishing for 15 minutes. Further, it was confirmed that not only the outer edge portion but also the center portion was polished and finished satisfactorily.
As a comparison, in the conventional polishing method under the same conditions (FIG. 7), Ra 0.26 μm before polishing and Ra 0.055 μm after polishing for 15 minutes, the improvement of the finished roughness remained.
From these, it was confirmed that the finishing method of the present invention has a polishing effect that is at least twice that of the conventional method. This can be inferred from the fact that the abrasive grains are disposed in the center of the workpiece by applying an electric field to the slurry containing the abrasive grains, and polishing is in progress. Furthermore, it was also confirmed that the difference in thickness between the center portion and the outer edge portion of the workpiece after polishing was suppressed. This proved that it has the effect of reducing the time of the planarization treatment.

[Example 2]
The effect on the polishing finish was compared under the same conditions as in Example 1.
In the finishing apparatus shown in FIGS. 3 and 5, as the slurry 37 to be supplied at the facing interval, a slurry in which 20 to 30 wt% of cerium oxide is dispersed in water is used.
Then, an electric field supply condition of an alternating electric field of 2 kV, 2.0 Hz, and an offset of 0.5 kV was given as a supply electric field.
As a result, a ground glass work piece 36 having a surface roughness Ra of 0.3 μm before polishing was finished to Ra 0.005 μm after polishing for 15 minutes by this polishing method.
For comparison, in the conventional polishing method under the same conditions, Ra 0.28 μm before polishing was Ra 0.049 μm after polishing for 15 minutes, and the finished roughness was only improved.
It was confirmed that not only the outer edge portion but also the center portion was sufficiently polished. It can be inferred that, by applying an electric field, abrasive grains are arranged at the center of the workpiece and polishing is in progress. Furthermore, it was also confirmed that the difference in thickness between the center portion and the outer edge portion of the workpiece after polishing was suppressed. Such a result is considered to be due to the formation of an environment in which polishing scraps are easily discharged well.

  Although the present invention has been described based on the embodiments of the drawings, the present invention is not limited to the above-described embodiments, and may be implemented in any way as long as the configuration described in the claims is not changed. Can do.

It is sectional drawing which shows the 1st aspect of this invention. It is a perspective view which shows an example of the formation method of the electrode plate in the 2nd aspect of this invention. It is sectional drawing which shows the 2nd aspect of this invention. It is a top view which shows one Example of the finishing apparatus of this invention. It is a top view which shows other one Example of the finishing apparatus of this invention. It is explanatory drawing shown about the applied electric field waveform in this invention. It is sectional drawing which shows the conventional finishing apparatus using a loose abrasive grain.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 12 Electrode plate 13 Insulating polishing pad 14 Workpiece 15 Planet carrier 16 Slurry in which dielectric abrasive grains are dispersed in water 21 Conductor 22 Insulator 31 Upper surface plate 32 Lower surface plate 33 Insulating layer 34 Insulating polishing pad 35 Planet carrier 36 Work piece 37 Slurry in which dielectric abrasive grains are dispersed in water

Claims (6)

An insulative polishing pad is attached to the lower surface of the electrode plate to form an upper surface plate, an insulative polishing pad is attached to the upper surface of the electrode plate to form a lower surface plate, and each surface plate of the above configuration is made to face each insulative polishing pad. It is possible to rotate in a state, a workpiece fitted on a rotatable planetary carrier is exposed at the facing interval, and a slurry in which dielectric abrasive grains are dispersed in water is supplied, and the water in the slurry is sensitive. By applying a square wave electric field with good rise at a low frequency in the plus range, and rotating the surface plate and the planet carrier in different speeds or in opposite directions, the front and back surfaces of the workpiece are further improved in quality. A finishing method using a fluid in which dielectric abrasive grains are dispersed in water under an electric field, which is finished with good polishing efficiency.   An electrode plate with alternating conductors and insulators is fixed to the lower surface of the insulating plate, and an insulating polishing pad is attached to the lower surface to form an upper surface plate. Conductors and insulators are alternately arranged on the upper surface of the insulating plate. 2. A finish using a fluid in which dielectric abrasive grains are dispersed in water according to claim 1, wherein the electrode plate is fixed, and an insulating polishing pad is attached to the upper surface thereof to form a lower surface plate. Method. An insulative polishing pad is attached to the lower surface of the electrode plate to form an upper surface plate, an insulative polishing pad is attached to the upper surface of the electrode plate to form a lower surface plate, and each surface plate of the above configuration is made to face each insulative polishing pad. A supply mechanism for supplying a slurry in which dielectric abrasive grains are dispersed in water, facing a workpiece fitted on a rotatable planet carrier at the facing interval; A control mechanism that can control electric field application and non-application intervals with a repetitive square wave electric field with a positive frequency that is sensitive to water and has a good rise, and each surface plate and planet carrier at different speeds or in opposite directions. A finishing device using a fluid in which dielectric abrasive grains under electric field are dispersed in water, comprising a rotating mechanism for rotating. An electrode plate with alternating conductors and insulators is fixed to the lower surface of the insulating plate, and an insulating polishing pad is attached to the lower surface to form an upper surface plate. Conductors and insulators are alternately arranged on the upper surface of the insulating plate. 4. A finish using a fluid in which dielectric abrasive grains are dispersed in water according to claim 3, wherein the electrode plate is fixed, and an insulating polishing pad is attached to the upper surface of the electrode plate to form a lower surface plate. apparatus. 5. A finishing apparatus using a fluid in which dielectric abrasive grains are dispersed in water under an electric field according to claim 4, wherein the conductor and the insulator are concentrically arranged. Use those arranged conductors and insulators in the small annular fluid where the dielectric grains are dispersed in water under electric field according to claim 4, characterized in that a plurality arranged in one plane of rotation Finishing equipment.

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