JP4262226B2 - Polishing apparatus and polishing method - Google Patents

Description

  The present invention relates to a polishing apparatus and a polishing method for polishing a surface of a workpiece using a grindstone.

  A grindstone is a tool formed by solidifying hard particles, that is, abrasive grains with a binder. There are two types of processing using a grindstone: grinding processing and polishing processing. Routine processing is customarily referred to as grinding processing, and finishing processing is referred to as polishing processing. In these processes, the surface of the workpiece, i.e., the surface to be processed, is moved by the abrasive grains by relatively moving the grindstone and the workpiece while the grindstone is pressed against the workpiece, i.e., the workpiece. The two are functionally synonymous, and in this specification, both are referred to as polishing.

  There are various types of workpieces that are polished using a grindstone. For example, a grindstone is used for polishing the surface of a sapphire substrate or a silicon substrate. Sapphire substrates are used to manufacture blue and white LEDs. These LEDs are manufactured by forming nitride semiconductor devices on a sapphire substrate by epitaxial growth, and the semiconductor integrated circuit is a single crystal such as silicon. It is manufactured by forming a semiconductor device on a substrate. A silicon substrate is manufactured by slicing a silicon ingot into a thin plate shape, and before forming a semiconductor device, a circuit forming surface is mirror-finished to a high surface roughness by polishing. Similarly, the surface of the sapphire substrate is finished by polishing.

  A sliced substrate is used as a workpiece, and the substrate is polished with a grindstone to mirror-finish the surface or reduce the thickness of the substrate. Tap water or water is used between the grindstone and the workpiece during polishing. A polishing liquid is applied to cool the grindstone and the workpiece.

  In order to cool the grindstone and the workpiece, the polishing liquid applied as a coolant to the grindstone surface during machining should be sufficiently inserted between the grindstone surface and the workpiece surface. Although it is necessary, the workpiece may be heated during the polishing process because the coolant does not sufficiently enter between the processing surface or the processing surface from the outside and the coolant does not sufficiently enter between the two. If the workpiece is partially overheated, thermal deformation or thermal distortion occurs in the workpiece, and high-quality polishing cannot be performed, resulting in a decrease in product yield.

  Since the polishing powder adheres to the processed surface of the grindstone and clogs are generated, the processed surface is polished for a predetermined time in order to remove the clogging and expose the abrasive grains to the processed surface. After finishing, dressing is performed using a dresser. This process is a process for removing the processed surface, and the processed surface is worn. Therefore, the grindstone on which the dressing process is repeated becomes thin and cannot be used.

  At the time of polishing using a grindstone, a predetermined pressing force is applied to the grindstone and the work piece so that the abrasive grains of the grindstone come into contact with the work surface at a predetermined surface pressure. On the other hand, thrust in the vertical direction is applied to the work surface. However, when thrust is applied from the outside, it is difficult to adjust the surface pressure with high accuracy, especially between the grindstone and the work piece. If the coolant applied to the surface is interposed, the abrasive grains do not reliably contact the surface to be processed, and the processing efficiency is reduced.

  An object of the present invention is to increase the cooling efficiency of a grindstone and a workpiece so that high-quality polishing can be performed.

  Another object of the present invention is to reduce the dressing frequency of the processed surface of the grindstone and increase the life of the grindstone.

  Another object of the present invention is to improve the working efficiency by adjusting the surface pressure applied to the abrasive grains of the grindstone.

The polishing apparatus of the present invention is a polishing apparatus that polishes a work surface of a workpiece, and includes a porous grindstone that has abrasive grains, a binder, and pores and is provided with a flat work surface. A driving means for relatively sliding the grindstone and the work piece in a state where the surface and the work surface are in contact with each other, and a grindstone holder to which the grindstone is attached. A fluid passage communicating with the machining surface via the pores, and a polishing gap connected between the fluid passage and formed between the workpiece surface and the machining surface is pressurized via the pores of the grindstone a pressurized fluid supply means for forming a flow of the fluid pressure in the polishing gap supplying fluid, connected to said fluid passageway, said pores of said grinding wheel in the negative pressure state, the fluid in the polishing gap Into the fluid passage through the pores. A negative pressure generating means, and having a pressure adjusting means for changing the thickness of the polishing gap by adjusting the pressure generated by the pressurized fluid supply means or said negative pressure generating means.

  The polishing apparatus of the present invention is characterized in that the abrasive grains are any one of diamond and CBN or a mixture thereof.

  In the polishing apparatus of the present invention, the grindstone includes a single element of diamond and CBN or a mixture thereof, or a mixture of at least one of the single element or the mixture and silicon carbide, mullite, or molten alumina. It has a polishing region and a sub-polishing region having a hardness lower than that of the main polishing region, including a single substance or a mixture of diamond, molten alumina, or silicon carbide.

The polishing method of the present invention is a polishing method for polishing a work surface of a workpiece, and is a work surface of a porous grindstone having abrasive grains, a binder, and pores and provided with a flat work surface. A polishing gap formed between the work surface and the work surface while relatively sliding the grindstone and the work piece in a state where the work surface is in contact with the work surface a first polishing step of forming a flow of the pressure fluid in through the pores of the grinding wheel by supplying a pressurized fluid the polishing gap, the pores of the grinding wheel to a negative pressure state, the And a second polishing step for generating a negative pressure for introducing a fluid into the polishing gap and guiding the fluid to the fluid passage through the pores, and generated in the first polishing step or the second polishing step. And adjusting the pressure to change the thickness of the polishing gap .

  According to the present invention, a porous grindstone having air permeability is penetrated so that a fluid such as air or liquid flows on the processing surface of the grindstone, so that the grindstone and the workpiece surface are efficiently cooled by the fluid. It is possible to reliably prevent overheating of the grindstone and the workpiece.

  According to the present invention, it is possible to prevent the abrasive powder from adhering to the processing surface of the grindstone by discharging the fluid from the grindstone toward the processing surface using the air permeability of the grindstone obtained by the pores of the grindstone. The clogging of the grindstone can be prevented. Thereby, the frequency of the dressing process of the grindstone can be reduced and the grindstone life can be extended.

According to the present invention, the processing step in which the polishing gap formed between the grindstone and the workpiece is in a pressure state higher than atmospheric pressure to form a flow of pressurized fluid in the polishing gap, and the polishing gap from atmospheric pressure. since polishing a workpiece by performing a processing step of forming a flow of fluid material in the polishing gap as low pressure conditions, it is possible to increase the polishing efficiency while preventing clogging of the grinding wheel. Further, the surface pressure applied by the abrasive grains to the workpiece can be adjusted, and the polishing accuracy can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1A to 1C are schematic views showing a polishing pattern in the case of polishing a flat surface of a workpiece using the polishing apparatus of the present invention, and the polishing is at least one of a grindstone and a workpiece. Is performed by relatively sliding the grindstone and the workpiece by rotating the.

  The polishing apparatus shown in FIG. 1A has a work table 1 that supports a workpiece W and a grindstone holder 2 that holds and rotates a grindstone G, and has a disk shape on the workpiece surface of the workpiece W. The grindstone G is slid with respect to the workpiece W by rotating the grindstone G as indicated by the symbol R in a state where the flat machining surface consisting of the end face of the grindstone G is in contact with the workpiece surface. Polishing is performed. In order to change the processing part by changing the relative position of the workpiece W and the grindstone G, the work table 1 is movable in the X direction and the Y direction in FIG. In this type of polishing apparatus, the relative position between the grindstone G and the workpiece W can be changed by moving the grindstone holder 2 in the X direction and the Y direction. The grindstone holder 2 may be moved to the other of the X direction and the Y direction.

  The polishing apparatus shown in FIG. 1B includes a grindstone holder 2 that fixes a grindstone G and a chuck 3 that holds and rotates the workpiece W, and the work surface of the workpiece W and the grindstone G are processed. By rotating the workpiece W in contact with the surface, the workpiece W is slid with respect to the grindstone G to polish the workpiece surface. In order to change the relative position between the workpiece W and the grindstone G, the chuck 3 is movable in the X direction and the Y direction.

  The polishing apparatus shown in FIG. 1C has a rotary table 1 that supports and rotates the workpiece W and a grindstone holder 2 that holds and rotates the grindstone G, and is provided on the workpiece surface of the workpiece W. The grindstone G is slid with respect to the workpiece W by rotating the rotary table 1 and the grindstone holder 2 as indicated by arrows R in a state where the flat work surface of the disc-shaped grindstone G is in contact. It is moved to polish the work surface. In order to change the relative position between the workpiece W and the grindstone G, the grindstone holder 2 is movable in the X direction.

  In the polishing apparatus shown in FIGS. 1A and 1C, the workpiece W is on the lower side and the grindstone G is on the upper side, and the workpiece surface is horizontal. The upper and lower relationships may be reversed, and the grindstone holder 2 and the table 1 may be arranged horizontally so that the work surface is vertical. Similarly, in the polishing apparatus shown in FIG. 1B, the vertical relationship between the workpiece W and the grindstone G may be reversed, and the grindstone holder 2 and the chuck 3 may be disposed horizontally.

  FIG. 2 is a cross-sectional view showing a polishing apparatus of the present invention of a type different from the type described above. 3A is a cross-sectional view showing the grindstone holder viewed from the direction along the line AA in FIG. 2, and FIG. 3B shows the same part as (A) in another type of polishing apparatus. It is sectional drawing.

  The polishing apparatus shown in FIG. 2 includes a chuck 11 that supports and rotates the workpiece W and a grindstone holder 12 that holds and rotates the grindstone G, and the grindstone G is placed on the processing surface Wa of the workpiece W. The grindstone G is slid with respect to the workpiece W by rotating the grindstone holder 12 and the chuck 11 in a state in which the machining surface Ga is in contact with the workpiece W, thereby polishing the workpiece surface Wa. In this polishing apparatus, the chuck 11 is disposed above the grindstone holder 12 and the respective rotation center axes are in the vertical direction. However, the vertical relationship between the chuck 11 and the grindstone holder 12 may be reversed. You may make it arrange | position horizontally so that an axis | shaft may become a horizontal direction.

  The chuck 11 is attached to the tip of the work rotation shaft 13 and serves as a vacuum chuck. The chuck 11 has a chuck plate 15 in which a plurality of intake holes 14 are formed, and the workpiece rotating shaft 13 is driven to rotate by a motor (not shown). A vacuum flow path 16 communicating with each intake hole 14 is formed in the work rotation shaft 13, and the vacuum flow path 16 is connected to a vacuum pump 18 via a rotary joint 17, and the vacuum pump 18 and the rotary joint 17 are connected to each other. A channel opening / closing valve 20 is attached to the vacuum supply channel 19 to be connected. Therefore, when the vacuum pump 18 is operated to set the vacuum flow path 16 to a pressure lower than the atmospheric pressure, external air flows into the intake hole 14 and the workpiece W is vacuum-adsorbed and held on the chuck 11.

  The workpiece rotating shaft 13 is movable in the vertical direction, and the workpiece W supported by the chuck 11 can be moved toward and away from the grindstone G, and the workpiece W is brought into contact with the grindstone G. In this state, a pressing force can be applied to the workpiece W by the dead weight of the workpiece rotating shaft 13 and the chuck 11. In addition to the pressing force due to its own weight, a pressing force may be applied to the workpiece W by applying a thrust to the workpiece rotating shaft 13 by a pneumatic cylinder or the like.

  The grindstone G is formed by solidifying abrasive grains with a binder, and has a porous structure in which fine pores are formed. As a result, fluid such as air or liquid can be passed between the flat processed surface Ga and the opposite side surface Gb through the continuous pores as shown in FIG. The grindstone G has air permeability. The grindstone G shown in the figure has an annular shape, the sealing treatment layer 10 is formed on the outer circumferential surface, and the inner circumferential surface is fitted and sealed with a protrusion provided on the grindstone support plate 23. However, it is also possible to prevent leakage of fluid from the inner and outer peripheral surfaces by attaching frames made of non-porous members to the outer peripheral surface and inner peripheral surface of the grindstone G.

  The grindstone holder 12 to which the grindstone G is attached is provided integrally with the grindstone rotating shaft 21 and has a grindstone support plate 23 in which a plurality of fluid guide holes 22 are formed. The grindstone rotating shaft 21 is a motor (not shown). Is driven to rotate. A fluid passage 24 communicating with each fluid guide hole 22 via a communication space 24 a is formed in the grindstone rotating shaft 21, and the fluid passage 24 is connected to a vacuum pump 26 via a rotary joint 25. A fluid on / off valve 28a and a pressure regulating valve 29a are attached to a fluid guide path 27a that connects the rotary joint 25. Therefore, when the vacuum pump 26 is operated with the flow path opening / closing valve 28a opened, the pores of the porous grindstone G communicate with the vacuum pump 26 via the fluid passage 24 and the fluid guide hole 22 and are large. A vacuum state or a negative pressure state lower than the atmospheric pressure is entered, and ambient air or liquid flows into the pores from the outside into the processed surface Ga of the grindstone G.

  A pressure pump 31 is connected to the rotary joint 25, and a channel opening / closing valve 28 b and a pressure adjustment valve 29 b are attached to the fluid guide channel 27 b connecting the pressure pump 31 and the rotary joint 25. The pressurization pump 31 pressurizes and discharges liquid such as tap water and polishing liquid stored in the container 32, and when the pressurization pump 31 is operated with the flow path opening / closing valve 28b opened, Enters the pores of the porous grindstone G through the fluid passage 24 and the fluid guide hole 22 and flows out of the processing surface Ga.

The vacuum pump 26 constitutes negative pressure generating means, the pressurizing pump 31 constitutes pressurized fluid supply means, and the pressure regulating valves 29a and 29b constitute pressure regulating means. In addition, you may make it let air flow out from the process surface Ga by making the pressurization pump 31 into the compressor which discharges compressed air.

  As shown in FIG. 3 (A), the fluid guide holes 22 may be formed in a distributed manner on the grindstone support plate 23 of the grindstone holder 12, and as shown in FIG. A plurality of communication holes 24 b communicating with the passage 24 may be formed, and the fluid guide holes 22 may be formed in the grindstone support plate 23 linearly in communication with each other.

  FIG. 4 is an enlarged cross-sectional view showing the grindstone G shown in FIG. 2 and a part of the workpiece W in contact with the grindstone G. The grindstone G connects a large number of abrasive grains 41 and the abrasive grains. A fine pore 43 is formed inside, and the grindstone G has air permeability so that a fluid flows between the processed surface Ga and the opposite side surface Gb. Yes. In order to allow fluid to flow in the grindstone G while maintaining the strength as the grindstone G, the porosity ε, that is, the ratio of the volume of the pores 43 to the grindstone volume is in the range of 10 to 60%, and the pore diameter is 1 Experiments have shown that it is preferable to be in the range of ~ 200 μm.

  When the processing surface Ga of the grindstone G is observed microscopically, it is an uneven surface according to the grain size of the abrasive grains 41, and the work surface Wa of the workpiece W before polishing is an uneven surface according to the surface roughness. Therefore, when the processing surface Ga and the processing surface Wa are brought into contact with each other, the processing surface Ga does not come into contact with the entire processing surface Wa when observed microscopically. A polishing gap S is formed in a layered manner between the processing surface Wa. The polishing void S is not formed in the portion where the abrasive grains 41 are in direct contact with the surface Wa to be processed, but the polishing void S forms a polishing layer that is continuously layered through a non-contact portion as a whole.

  Accordingly, when the work surface Ga and the work surface Wa are pressed against each other, when the vacuum pump 26 is operated and the pores 43 in the grindstone G are brought into a negative pressure state via the fluid passage 24, the grindstone G is Since it has air permeability, external air flows into the grindstone G from the processing surface Ga, and an air flow is formed in the polishing gap S formed between the processing surface Ga and the processing surface Wa. The grindstone G and the workpiece W are both cooled by the air flowing through the polishing gap S. When a liquid such as tap water or a polishing liquid is applied to the grindstone G and the workpiece W, the liquid penetrates through the pores of the grindstone G together with the air to cool the grindstone G. The grindstone G is cooled.

In addition, the pressure of the polishing gap S is set to a predetermined degree of vacuum by the vacuum pump 26 as a negative pressure generating means, and when the polishing gap S is in a vacuum state, the adhesion between the processing surface Ga and the processing surface Wa increases. Thus, the surface pressure applied to the processing surface Ga and the processing surface Wa can be increased, and the abrasive grains 41 are in direct contact with the processing surface Wa, and polishing is performed without bringing the polishing gap S into a negative pressure state. The polishing amount per unit time can be increased as compared with the case. When the pressure of the polishing gap S is changed by the pressure adjusting valve 29a as the pressure adjusting means, the thickness of the polishing gap S and the surface pressure can be changed. It can be adjusted by adjusting the pressure.

  For example, if the degree of vacuum of the polishing gap S is increased and the surface pressure is increased, the number of abrasive grains 41 on the processed surface Ga in contact with the processing surface Wa can be increased, and the amount of polishing can be increased. When the pressure of the polishing gap S is brought close to atmospheric pressure, the number of abrasive grains in contact with the processing surface Wa is reduced and the polishing amount is reduced, but the finishing accuracy of the processing surface Wa can be increased. Therefore, even if the same grindstone G is used, the polishing amount and the finished surface roughness of the work surface Wa can be changed by adjusting the pressure of the polishing gap S.

  On the other hand, when the processing surface Ga and the processing surface Wa are pressed, the pressure pump 31 is operated to inject the liquid into the pores 43 in the grindstone G through the fluid passage 24. Since it is discharged from the processing surface Ga into the polishing gap S, a liquid flow is formed between the processing surface Ga and the processing surface Wa, and the grindstone G and the workpiece W are both caused by the flowing liquid. To be cooled. In addition, when the pressure of the liquid in the polishing gap S is set to a predetermined pressure higher than the atmospheric pressure by the pressurizing pump 31 as the pressurized fluid supply means, the polishing gap S between the processing surface Ga and the processing surface Wa. As a result, the surface pressure applied to the processed surface Ga and the processed surface Wa can be reduced. When the pressure of the polishing gap S is changed by the pressure adjusting valve 29b as the pressure adjusting means, the thickness of the polishing gap S is changed and the surface pressure can be changed. Therefore, the polishing amount and the finished surface roughness of the work surface Wa are changed. Can be adjusted by adjusting the pressure of the polishing gap S.

  In addition, when the liquid is discharged from the grindstone G into the polishing gap S, the abrasive powder is prevented from adhering to the processed surface Ga during the grinding process, so that the clogging of the grindstone G can be prevented. The processing efficiency can be improved by greatly reducing the frequency of dressing. Accordingly, the vacuum pump 26 is operated to perform a predetermined polishing process by setting the inside of the polishing gap S to a pressure lower than the atmospheric pressure, and the polishing process is performed by supplying liquid or air from the pressure pump 31 to the grindstone G. In addition to adjusting the surface pressure of the grindstone, it is possible to perform polishing while flowing a fluid through the polishing gap S, and to remove polishing powder adhering to the processing surface Ga during processing. The dressing frequency can be greatly reduced.

  FIG. 5 is a perspective view showing the grindstone G shown in FIG. 2. The grindstone G has a main polishing region 45 and a sub-polishing region 46, each extending in the thickness direction of the grindstone G. 45 has a grinding wheel hardness higher than that of the sub-polishing region 46. Each of the polishing regions 45 and 46 is formed by solidifying the abrasive grains 41 and the binder 42 together by sintering, and has pores 43 formed therein so as to have air permeability. The main polishing region 45 is square on the processing surface Ga and has a lattice shape as a whole, and the inside thereof is a sub-polishing region 46. However, the planar shape of the main polishing region 45 is not limited to a quadrangle, and may be a hexagonal shape or an octagonal shape, or may be formed in a parallel line shape or a radial shape.

As the abrasive grains 41 in the main polishing region 45 shown in the figure, diamond, that is, diamond abrasive grains, is used, and the average particle diameter is 0.1 to 300 μm. However, instead of diamond, cubic boron nitride (CBN) abrasive grains, that is, CBN may be used, or a mixture of diamond and CBN may be used. On the other hand, as the abrasive grains 41 in the sub-polishing region 46, silicon carbide SiC or GC, mullite (3Al ₂ O ₃ -2SiO ₂ ), or molten alumina Al ₂ O ₃ or WA, which has a lower hardness than diamond or CBN. Or a mixture thereof is used, and the average particle size is 0.1 to 300 μm. As described above, by using diamond as the abrasive grains 41 in the main polishing region 45 and not using diamond in the abrasive particles 41 in the sub-polishing region 46, the amount of diamond used can be reduced. The abrasive grains 41 of the grindstone G may all be formed of diamond or CBN without forming the main polishing area 45 and the sub-polishing area 46 that are different from each other.

  Vitrified bonds are used as the bonding material 42 of the main polishing region 45 and the sub-polishing region 46. As the bonding materials 42, various bonds such as resinoid bonds, metal bonds, electrodeposition bonds, etc., other than vitrified bonds are used. Material can be used.

  Thus, the sub-polishing region 46 is formed by abrasive grains 41 made of fused alumina, mullite, or silicon carbide, and the main polishing region 45 is formed by using diamond having a hardness higher than that as the abrasive grains 41. When the grinding process is performed using the grindstone G, the processing surface Ga of the sub-polishing region 46 is worn before the processing surface Ga of the main polishing region 45, and the processing surface Ga of the main polishing region 45 is the sub-polishing region. The edge of the processing surface Ga protrudes about 10 μm from the processed surface Ga of 46 and is mainly polished by the edge, and the edge of the cutting edge is always created in the main polishing region 45 by the polishing process. . However, the abrasive grains 41 in the sub-polishing region 46 may contain diamond.

  If the sub-polishing region 46 is worn earlier than the main polishing region 45, that is, if the wear amount of the processing surface Ga of the grindstone G is larger than that of the main polishing region 45, the abrasive grains 41 constituting each region The type of the binding material 42 is not limited to the case described above. For example, the abrasive grains 41 in the respective polishing regions 45 and 46 may be the same kind of abrasive grains, and the respective binders 42 may be made different. Further, the abrasive grains 41 in the respective regions may be of the same type, and the abrasive grain size in the main polishing region 45 may be made larger than the abrasive grain size in the sub-polishing region 46. The material 42 may be the same or different. That is, in order to realize that the sub-polishing region 46 is worn before the main polishing region 45, that is, the amount of wear of the sub-polishing region 46 is larger than that of the main polishing region 45, first, the type of each abrasive grain 41 The optimum grindstone G can be obtained by one or a combination of the method of adjusting the size and amount, and the second method of appropriately setting the type, amount, etc. of the respective binding materials 42.

  Thus, it is sufficient that the hardness of the main polishing region 45 is higher than that of the sub-polishing region 46, that is, it is set so as not to wear easily. As the sub-polishing region 46, either diamond or CBN alone or a mixture thereof, Alternatively, these simple substances or a mixture thereof and at least one of silicon carbide, mullite, and molten alumina can be used. In the case of using a single body of diamond and CBN or a mixture of these and other abrasive grains, it contains a single body of diamond and CBN or a mixture thereof in a volume ratio of 10 to 100%, and a binder The main polishing region 45 including 42 preferably contains diamond and CBN alone or a mixture thereof in a volume ratio of 5 to 65%.

  As shown in FIG. 5, when polishing is performed using a grindstone G having a main polishing region 45 and a sub-polishing region 46, the surface of the workpiece W has a processed surface Ga of the sub-polishing region 46 and a hardness higher than this. The processing surface Ga of the main polishing region 45 having a high height is repeatedly contacted. Thereby, as described above, the processing surface Ga of the sub-polishing region 46 is worn before the processing surface Ga of the main polishing region 45, and the abrasive grains 41 that are missing from the grindstone G during the polishing process are missing. Then, it enters the polishing gap S and functions as a kind of loose abrasive grains. Thus, since the missing abrasive grains function as a kind of loose abrasive grains, the processed surface Ga of the main polishing region 45 protrudes from the processed surface Ga of the sub-polishing region 46, that is, a dressed state. Thus, since the polishing process is performed, a good polishing process quality can be obtained without leaving a deep indentation on the processing surface Wa while maintaining the polishing ability for the workpiece W due to the dressing effect. Furthermore, the work surface Wa of the work piece W is mainly polished by the work surface Ga of the main polishing region 45 and supplementarily ground by the work surface Ga of the sub-polishing region 46. Since the processing surface Ga wears faster than the processing surface Ga of the main polishing region 45, the cutting edge is always exposed on the processing surface Ga of the main polishing region 45.

  Moreover, since the processing surface Ga in the main polishing region 45 protrudes beyond the processing surface Ga in the sub-polishing region 46, the pressing force applied to the workpiece W by the grindstone G causes the abrasive grains 41 in the main polishing region 45 to be pressed. A large shared load is applied, and the surface pressure applied to the abrasive grains 41 increases. Thereby, the function which scrapes off the surface of the to-be-processed object W by the abrasive grain 41 increases, and processing efficiency improves. This is achieved even when the polishing void S is in a negative pressure state lower than the atmospheric pressure and the surface pressure applied to the work surface Wa and the abrasive grains is increased, and the polishing efficiency can be increased.

  6A is a side view showing the overall configuration of the polishing apparatus shown in FIG. 2, FIG. 6B is a front view of FIG. 6A, and FIG. 7 is B in FIG. 6B. It is an expanded sectional view which follows the -B line.

  The polishing apparatus includes a base 51 in which the grindstone rotating shaft 21 shown in FIG. 2 is rotatably incorporated, and a polishing head 52 provided on the base 51. The polishing head 52 includes two polishing heads. Work rotation shafts 13 are rotatably provided. Therefore, the illustrated polishing apparatus can polish two workpieces W at the same time.

  A pulley 53 is fixed to the grindstone rotating shaft 21 as shown in FIG. 7, and a belt 56 is provided between the pulley 55 of the motor 54 fixed to the base 51 and the pulley 53 as shown in FIG. The grindstone rotating shaft 21 is driven to rotate by a motor 54. A hose 57 constituting a fluid guide path is connected to the rotary joint 25 attached to the grindstone rotating shaft 21, and the vacuum pump 26 and the pressure pump shown in FIG. 2 are connected to the rotary joint 25 via the hose 57. Either or both of 31 are connected.

  The polishing head 52 is provided with a slide base 59 that slides along a guide rail 58 that is fixed to the polishing head 52 in the horizontal direction. Each work rotation shaft 13 is movable in the vertical direction on the slide base 59. And it is rotatably provided. A spline 61 is provided on the upper end side of each work rotating shaft 13, and a pulley 62 meshing with the spline 61 is rotatably incorporated in a slide base 59, and a motor 63 fixed to the pulley 62 and the slide base 59. A belt 65 is stretched between the pulley 64 and the work rotation shaft 13 is driven to rotate by the motor 63. The work rotation shaft 13 is incorporated in a sleeve 65 that is mounted on the slide base 59 so as to be movable up and down. The work rotation shaft 13 is moved up and down via the sleeve 65 and moved toward and away from the grindstone G. For this purpose, the piston rod 67 of the pneumatic cylinder 66 attached to the slide base 59 is connected to the sleeve 65. A rotary joint 17 is attached to the end of the work rotation shaft 13 and this rotary joint 17 is connected to a vacuum pump 18 as shown in FIG. FIG. 7 shows one of the two workpiece rotating shafts 13 provided on the polishing head 52 as shown in FIG. 6, both of which have the same structure.

  In order to polish the surface of the disk-shaped workpiece W by the polishing apparatus shown in FIGS. 5 and 6, the pneumatic cylinder 66 is used with the workpiece W held by the respective vacuum chucks 11. The work rotation shaft 13 is moved toward the grindstone G. The workpiece rotating shaft 13 is rotated by the motor 63 and the processing surface Wa of the workpiece W is brought into contact with the processing surface Ga of the grindstone G while rotating the grindstone rotating shaft 21 by the motor 54. The grindstone G and the workpiece W are slid relative to each other by both the motors 54 and 63, and when the vacuum pump 26 is driven in this state, the grinding wheel G and the workpiece surface Wa are formed. A negative pressure air flow is generated in the polishing gap S through the pores of the grindstone G, and the inside of the polishing gap S is in a negative pressure state, and a pressure lower than the atmospheric pressure is generated. On the other hand, when air or liquid is supplied from the pressurizing pump 31 into the polishing gap S, a pressure higher than the atmospheric pressure is generated in the polishing gap S. The respective pressures are adjusted by pressure adjusting valves 29a and 29b. Thus, by adjusting the pressure in the polishing gap S and changing the thickness of the polishing gap S, the number of abrasive grains 41 in contact with the work surface Wa can be changed, and the polishing amount and the finish of the work surface Wa are finished. The accuracy can be adjusted.

As a polishing method using the polishing apparatus of the present invention, a fluid such as a liquid is supplied from a pressurizing pump 31 to a polishing gap S between a processing surface of a workpiece and a processing surface of a grindstone. a polishing step for forming a flow of pressurized fluid to, and the negative pressure state by the vacuum pump 26 to the polishing gap S, there execute a polishing step for forming a flow of supply air abrasive gap S in the flow body Furthermore, if these polishing steps are repeated alternately several times, the dressing frequency of the grinding wheel is reduced to increase the grinding wheel life, and the cooling efficiency of the grinding wheel and the workpiece can be increased to perform high-quality polishing. it can.

  As a polishing method using the polishing apparatus of the present invention, the polishing process is further performed by changing the pressure in the polishing gap S with the progress of the polishing process by the pressure adjusting valves 29a and 29b during each polishing process. There is a method of performing, and the amount of polishing per unit time can be changed by changing the pressure.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the polishing apparatus of the present invention can be applied to the various types of polishing apparatuses shown in FIG. 1 as long as the processing surface Ga and the processing surface Wa are in a sliding state.

(A)-(C) are schematic which shows the grinding | polishing processing pattern in the case of grind | polishing the plane of a to-be-processed object using a grindstone. It is sectional drawing which shows the grinding | polishing apparatus which is one embodiment of this invention. (A) is sectional drawing which shows the grindstone holder seen from the direction in alignment with the AA in FIG. 2, (B) is sectional drawing which shows the part similar to (A) in other types of grinding | polishing apparatus. . It is sectional drawing which expands and shows a part of workpiece in the state contacted with the grindstone shown by FIG. FIG. 3 is a perspective view showing the grindstone shown in FIG. 2. (A) is a side view which shows the whole structure of the grinding | polishing apparatus shown in FIG. 2, (B) is a front view of (A). It is an expanded sectional view which follows the BB line in Drawing 6 (B).

Explanation of symbols

11 Chuck 12 Grinding wheel holder 13 Work rotation shaft 21 Grinding wheel rotation shaft 22 Fluid guide hole 24 Fluid passage 25 Rotary joint 26 Vacuum pump 29a, 29b Pressure adjusting valve 31 Pressure pump 41 Abrasive grain 42 Bonding material 43 Pore 45 Main polishing area 46 Secondary Polishing area G Grinding wheel Ga Processing surface S Polishing gap W Workpiece Wa Waving surface

Claims (4)

A polishing apparatus for polishing a workpiece surface of a workpiece,
A porous grindstone having abrasive grains, binders and pores and provided with a flat working surface;
Driving means for relatively sliding the grindstone and the workpiece under a state in which the processing surface and the processing surface are in contact with each other;
A fluid passage formed in a grindstone holder to which the grindstone is attached, and communicating with the processing surface via the pores of the grindstone;
Connected to the fluid passage, wherein is pressure in the polishing gap through the pores of the grinding wheel by supplying a pressurized fluid to the polishing gap formed between the workpiece surface and the processing surface fluid Pressurized fluid supply means for forming a flow of
Connected to the fluid passage, the pores of the grindstone are brought into a negative pressure state, a fluid is flowed into the polishing gap from the outside to form a fluid flow in the polishing gap, and the fluid is passed through the pores to the fluid. Negative pressure generating means for guiding to the passage ;
A polishing apparatus comprising pressure adjusting means for adjusting the pressure generated by the pressurized fluid supply means or the negative pressure generating means to change the thickness of the polishing gap .   The polishing apparatus according to claim 1, wherein the abrasive grains are any one of diamond and CBN or a mixture thereof.   2. The polishing apparatus according to claim 1, wherein the grindstone is one of diamond and CBN or a mixture thereof, or the single or the mixture and at least one of silicon carbide, mullite, and molten alumina. A polishing apparatus, comprising: a main polishing region including: and a sub-polishing region having a hardness lower than that of the main polishing region including a simple substance or a mixture of diamond, molten alumina, or silicon carbide. A polishing method for polishing a workpiece surface of a workpiece,
The grindstone and the work piece are in contact with the work surface and the work surface of a porous grindstone having abrasive grains, binders and pores and provided with a flat work surface. While relatively sliding
First to form a flow of the fluid pressure in the polishing gap supplying pressurized fluid through the pores of the grinding wheel to the grinding gap formed between the workpiece surface and the processing surface Polishing process of
Performing a second polishing step in which the pores of the grindstone are brought into a negative pressure state, a fluid is caused to flow into the polishing gap, and a negative pressure is generated to guide the fluid to the fluid passage through the pores ;
A polishing method comprising adjusting the pressure generated in the first polishing step or the second polishing step to change the thickness of the polishing gap.

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