JP2012056081A - Lapping method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lapping method and device of a spherical body, capable of enhancing lapping process efficiency.SOLUTION: The lapping method is a lapping method of a spherical body, in which a lapping is performed, by grinding stones 2a and 3a, for the surface of a spherical machining sample 7 made of silicon nitride ceramics and sialon ceramics and the grinding stones 2a and 3a include abrasive grains having hardness higher than that of the machining sample 7. The lapping is performed by supplying a machining liquid, including particles making the machining sample 7 cause tribochemical reaction, to the part between the machining sample 7 and the grinding stones 2a and 3a.

Description

  The present invention relates to a lapping method and a processing apparatus, and more particularly to a lapping method and a processing apparatus for lapping a surface of a workpiece made of silicon nitride ceramics or sialon ceramics with an abrasive material.

  Since silicon nitride ceramics and sialon ceramics have excellent mechanical properties such as high strength, high hardness, high heat resistance, and high corrosion resistance, they are used as mechanical parts such as bearings and engine parts. On the other hand, since it has excellent mechanical strength as described above, silicon nitride ceramics and sialon ceramics have difficult-to-grind properties when viewed from the processed surface. For this reason, high-hardness grindstones and abrasive grains such as diamond and CBN are used for grinding silicon nitride ceramics and sialon ceramics, and the processing efficiency and processing speed are not so fast.

  As a technique for improving machining efficiency without causing a fatal defect in a ceramic material, Japanese Patent Laid-Open No. 7-132448 (Patent Document 1) discloses a technique for optimizing the peripheral speed and feed speed of the working surface of a grinding wheel. It is disclosed. Specifically, a technique is disclosed in which the peripheral speed of the working surface of the grinding wheel is 50 to 300 m / sec and the feed speed of the working surface of the grinding wheel in the working direction is 50 to 200 m / min.

  However, for example, when a final lapping process is performed on a spherical ceramic material, a relatively slow condition in which the relative speed between the grindstone and the workpiece is 250 m / min or less is applied. Since the technique of the above-mentioned patent document 1 assumes the case of grinding ceramics at a relatively high processing speed, it could not be applied to the processing conditions when finishing lapping processing of ceramic materials. .

  Japanese Patent Laid-Open No. 2000-210862 (Patent Document 2) discloses a method for processing a ceramic sphere, in which a sphere is sandwiched between opposing polishing surfaces of a pair of coaxially arranged disks, and one of the disks is attached to the other. In a polishing method in which a sphere is polished by rotating the shaft relatively with respect to the above, it is disclosed that a lapping solution having a different polishing effect is used. In this technique, the lapping liquid mixed with loose abrasive grains can be involved in the sharpening action of the grindstone surface plate to increase the polishing amount. However, although it is possible to prevent a reduction in the processing efficiency due to clogging of the grindstone, in principle, the processing efficiency is not improved. Moreover, since the wear of the grinding wheel surface plate is promoted by the action of the loose abrasive grains, there is a problem in running cost.

  Japanese Patent Laid-Open No. 5-84656 (Patent Document 3) and Japanese Patent Laid-Open No. 8-257897 (Patent Document 4) disclose a polishing method using a magnetic fluid. Although this method can perform a highly efficient lapping process, the apparatus configuration is complicated due to the use of magnetic fluid, and the number of processed parts per lot is small, so that it is not suitable for mass production processing. In particular, sphere lapping requires that there is no variation in the average diameter of the spheres. However, in this method, when a large number of spheres are manufactured, it is necessary to make the average diameters between lots uniform and process control is extremely difficult.

As another technique that can improve the efficiency of the lapping treatment of the ceramic material, Japanese Patent Application Laid-Open No. 2003-145416 (Patent Document 5) discloses a technique using a tribochemical reaction. Specifically, it is a polishing material composed of a ceramic sintered body, and includes an element that causes the ceramic to be polished to react at one or more kinds of grain boundaries, grains, and pores of the sintered body. A technique for polishing a ceramic material in water using a polishing material that has been disclosed is disclosed. Thereby, since wear of a ceramic material can be promoted in water, the efficiency of the lapping process can be improved.

JP 7-132448 A JP 2000-210862 A JP-A-5-84656 JP-A-8-257897 JP 2003-145416 A

  However, in the technique of Patent Document 5, the abrasive material is a ceramic sintered body. For this reason, in order to manufacture an abrasive material, it is necessary to mix materials to be polished ceramics and perform pressure molding and sintering in a rare gas atmosphere. Need to pass. In addition, since the polishing material is made of a ceramic sintered body, the size and shape of the polishing material are also limited. As a result, since it is difficult to mass-produce the polishing material, it is difficult to improve the lapping efficiency of the sphere.

  Therefore, an object of the present invention is to provide a lapping method and a processing apparatus that can improve the lapping efficiency of a sphere.

The lapping method of the present invention is a lapping method for a sphere in which the surface of a workpiece made of silicon nitride ceramics or sialon ceramics is lapped with an abrasive material, and the abrasive material has a higher hardness than the workpiece. Is included. A liquid containing particles that cause a tribochemical reaction on the workpiece (hereinafter also referred to as the above-mentioned particles) is supplied between the workpiece and the polishing material to perform lapping.

  The lapping apparatus of the present invention is a spherical lapping apparatus that lappings the surface of a workpiece made of silicon nitride ceramics or sialon ceramics with an abrasive material, and includes polishing grains that are harder than the workpiece. A supply unit for supplying a liquid containing a material and particles that cause a tribochemical reaction to the workpiece between the workpiece and the polishing material, and discharging the liquid containing the workpiece from the polishing material And a housing having a first tank and a second tank. The liquid discharged from the drainage section is supplied to the first tank, the liquid overflowing from the first tank flows into the second tank, and the liquid in the second tank is supplied from the supply section.

  The inventor of the present application, as a result of intensive investigations on effective means for improving the efficiency and reducing the cost of lapping treatment of silicon nitride ceramic spheres and sialon ceramic spheres, has resulted in a liquid containing particles that cause a tribochemical reaction on the workpiece. The present inventors have found that it is effective to supply between a workpiece and a polishing material containing abrasive grains having a hardness higher than that of the workpiece. That is, according to the lapping method and the processing apparatus of the present invention, a tribochemical reaction occurs on the friction surface of the workpiece, and a reaction product of the workpiece is generated. The abrasive material removes this reaction product and, at the same time, mechanically removes the workpiece, creating a new workpiece surface. Then, the tribochemical reaction occurs again on the surface of the new workpiece, and a reaction product of the workpiece is generated. In the present invention, such an action occurs repeatedly. As a result, the surface of the workpiece can be removed chemically and mechanically, so that the lapping processing efficiency can be improved.

Here, the tribochemical reaction is a phenomenon in which when a friction is applied to a workpiece, a chemical reaction proceeds on the friction surface due to the frictional energy to generate a reaction product. According to the tribochemical reaction, the chemical reaction can be caused even at a temperature and an atmosphere where the chemical reaction on the surface does not proceed. Since the reaction product of the workpiece is usually softer than the original workpiece, it is easier to remove than the workpiece itself.

  Further, according to the lapping method and processing apparatus of the present invention, since the polishing material does not need to be made of a ceramic sintered body, it is not necessary to go through a complicated manufacturing process to manufacture the polishing material. There are no restrictions on the size and shape of the. The liquid can be easily obtained by adding particles that cause a tribochemical reaction to the workpiece. Therefore, the wrapping efficiency can be improved. Moreover, deterioration of the polishing material can be suppressed.

  In addition, according to the lapping method and processing apparatus of the present invention, since abrasive grains that are harder than the workpiece are selected as the polishing material, deformation of the polishing material during polishing can be suppressed, and polishing accuracy can be improved. Can be improved. Further, since the polishing material scraped off by the polishing is removed by the liquid, the polishing material is not easily clogged, and the lapping processing efficiency is improved.

  In addition, according to the lapping apparatus of the present invention, the particle size of foreign matter (polishing powder, dropped abrasive grains, etc.) contained in the liquid supplied to the first tank causes a tribochemical reaction in the workpiece. Since the particle size is larger than the particle size, the sedimentation rate of the foreign matter is faster than the particle sedimentation rate. For this reason, the foreign matter stays at the bottom of the first tank and does not easily flow into the second tank, but the particles are uniformly dispersed in the first tank and flow into the second tank at substantially the same concentration as the first tank. As a result, the liquid from which only the foreign matter is removed can be supplied again, and the liquid can be recycled and used.

  In the lapping method and processing apparatus of the present invention, the liquid is preferably an emulsion-type water-soluble cutting oil or a solution-type water-soluble cutting oil.

  Thereby, the liquid serves as a lapping liquid and also serves as a dispersion solvent for the particles. Moreover, clogging of the polishing material can be prevented. Furthermore, by using an emulsion-type water-soluble cutting oil or a solution-type water-soluble cutting oil, the particles can be uniformly dispersed in the liquid.

  In the lapping method and processing apparatus of the present invention, preferably, the liquid is made of water or an aqueous solution, and the pH of the liquid is 9 or more and 12 or less.

  Thereby, the liquid serves as a lapping liquid and also serves as a dispersion solvent for the particles. In order to uniformly disperse particles in water or an aqueous solution, it is desirable to charge the surface potential positively or negatively. In a neutral region of pH 5 or more and less than pH 9, the surface potential of the particles is near 0, and the particles tend to aggregate with each other. Although the particles are easily dispersed in the acidic region below pH 5, there is a problem that the processing apparatus and the polishing material are corroded and there is a concern about the safety of handling the liquid. In the alkaline region of pH 9 or more and pH 12 or less, the dispersion of the particles is good, and there is no problem of corrosion of the processing apparatus or the polishing material, and the safety of handling the liquid is not so much a problem. In the alkaline region where the pH is greater than 12, there is a problem that the processing apparatus and the abrasive material corrode and there is a concern about the safety of the liquid handling.

  In the lapping method and processing apparatus of the present invention, preferably, the hardness of the particles is equal to or lower than the hardness of the workpiece.

Thereby, while the workpiece causes a tribochemical reaction by the particles, it is possible to prevent the particles from causing unnecessary processing scratches and defects.

  Preferably, in the lapping method and the processing apparatus of the present invention, the particles are made of an oxide of at least one element selected from the group consisting of silicon, iron, chromium, and titanium.

  These oxides are suitable as the particles because they have an effect of promoting the tribochemical reaction of ceramics.

  In the lapping method and processing apparatus of the present invention, the abrasive grains are made of at least one material selected from the group consisting of diamond, CBN, and boron carbide, and the grain size of the abrasive grains is smaller than No. 400. It is especially effective in cases.

  The above materials are suitable as abrasive grains because of their excellent hardness. Further, when the abrasive grains are processed under the condition that the grain size is finer than No. 400, preferably finer than No. 800, the removal amount of the reaction product of the workpiece by the tribochemical reaction is mechanical. Therefore, a large synergistic effect between chemical removal and mechanical removal can be obtained.

  Preferably, in the lapping method of the present invention, in a pair of coaxially arranged discs having the abrasive material attached to at least one of them, a sphere is sandwiched between the abrasive material surfaces facing each other, and one of the discs is rotated. A method of processing a sphere for polishing the sphere. More preferably, it is a method of lapping a sphere in which a groove on which the sphere rolls is formed coaxially with the rotation axis on the surface of at least one of the disks to which the abrasive material is attached.

Thereby, the lapping process can be performed on the spherical workpiece.
In the lapping method and processing apparatus of the present invention, the liquid is preferably at a temperature higher than room temperature and not higher than 80 ° C., more preferably not higher than 60 ° C.

  By making the temperature of the liquid higher than room temperature, the tribochemical reaction is promoted, and the lapping processing efficiency can be further improved. Moreover, the safety | security of work and the ease of management are securable by making the temperature of a liquid into 80 degrees C or less, More preferably, 60 degrees C or less.

  Preferably, the lapping apparatus of the present invention further includes a control device for controlling the temperature of the liquid supplied from the supply unit.

  Thereby, since the temperature of the liquid can be controlled to a temperature suitable for the lapping process, the lapping process efficiency can be further improved.

  According to the lapping method and the processing apparatus of the present invention, the lapping efficiency can be improved.

It is a perspective view which shows the main structures of the spherical lapping apparatus in one embodiment of this invention. It is sectional drawing which shows the structure of the tank of the lapping apparatus in one embodiment of this invention. It is a figure which shows the relationship between the process liquid temperature in Example 3 of this invention, and a process speed ratio.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a configuration of a wrapping apparatus for a sphere in one embodiment of the present invention. Referring to FIG. 1, a spherical lapping apparatus 1 in the present embodiment mainly includes two surface plates 2 and 3, a supply pipe 4, a drain pipe 5, and a tank 6. The structure of the tank 6 will be described later. Both the surface plates 2 and 3 have a circular planar shape, and grooves 2 a and 3 a are formed in a grindstone mounted on each surface of the surface plates 2 and 3. The grooves 2a and 3a formed on the two surface plates are arranged facing each other so as to sandwich each of the plurality of processed samples 7. The rotating shaft of the surface plate 3 is connected to a pulley, and the surface plate 3 is driven by a rotating mechanism including a motor, a pulley, and a belt (all not shown). On the other hand, the surface plate 2 is pressed with an appropriate pressure toward the surface plate 3 by a pressing mechanism such as a hydraulic cylinder (not shown).

  One end of a supply pipe 4 is connected between the surface plates 2 and 3. The supply pipe 4 extends into the tank 6 via a pump (not shown). The machining fluid 8 (FIG. 2) is supplied between the machining sample and the grindstone by the supply pipe 4. A drain pipe 5 is connected under the surface plates 2 and 3, and the drain pipe 5 extends into the tank 6. The machining liquid 8 is drained into the tank 6 through the drain pipe 5 and supplied between the surface plates 2 and 3 through the supply pipe 4 from the tank 6.

  The processed sample 7 on the rotary conveyor (not shown) is supplied between the groove 2a of the surface plate 2 and the groove 3a of the surface plate 3 via the chute 9, and is polished by the grindstones of the grooves 2a and 3a. After that, it is discharged onto the conveyor via the chute 10.

  The grindstones 2 a and 3 a include abrasive grains that are harder than the processed sample 7. Specifically, abrasive grains made of diamond, CBN, boron carbide or the like are included. The grain size of the abrasive grains is smaller than 400, preferably smaller than 800. This is because the processing amount of the reaction product of the workpiece by the tribochemical reaction becomes larger relative to the removal amount of the workpiece to be mechanically removed as the finer grain is processed. This is because a great synergistic effect between the mechanical removal and the mechanical removal can be obtained. Moreover, the grindstones 2a and 3a are being fixed to the surface plates 2 and 3 using binders, such as a resin bond, a vitrified bond, a metal bond, or an electrodeposition bond, for example.

  FIG. 2 is a cross-sectional view showing the configuration of the tank of the lapping apparatus according to one embodiment of the present invention. Referring to FIG. 2, spherical lapping apparatus 1 in the present embodiment further includes a tank 6 as a housing. The tank 6 has three staying tanks 11a to 11c, and each of the staying tanks 11a to 11c is filled with the processing liquid 8. The liquid level of the processing liquid 8 is the highest in the retention tank 11a (first tank), the second highest in the retention tank 11b, and the lowest in the retention tank 11c (third tank). Thereby, the working liquid 8 overflowing from the upper part of the staying tank 11a flows into the staying tank 11b, and the working liquid 8 overflowing from the upper part of the staying tank 11b flows into the staying tank 11c. Further, the other end of the drain pipe 5 is inserted into the staying tank 11a, whereby the working liquid 8 discharged from the drain pipe 5 is supplied to the staying tank 11a. Further, the other end of the supply pipe 4 is inserted into the staying tank 11c via the pump 14, whereby the machining fluid 8 in the staying tank 11c is supplied from the supply pipe 4 to the grindstones 2a and 3a by the power of the pump 14. The That is, the machining liquid 8 is used after being circulated through the tank 6 or the like.

  A thermometer 13 is provided in the staying tank 11c. A heater 14 a is attached to the outer periphery of the tank 6, and a heater 14 b is attached to the outer periphery of the supply pipe 4. Each of the thermometer 13 and the heaters 14 a and 14 b is electrically connected to the temperature control device 12. The temperature control device 12 heats the heaters 14 a and 14 b based on the temperature measured by the thermometer 13, thereby controlling the temperature of the machining fluid 8. As a result, the machining liquid 8 having an appropriate temperature can be supplied onto the grindstones 2a and 3a. The temperature of the working fluid 8 is preferably higher than room temperature and 80 ° C. or less, and more preferably 60 ° C. or less. By making the temperature of the working fluid 8 higher than room temperature, the tribochemical reaction is promoted, and the lapping processing efficiency can be further improved. Moreover, the safety | security of work and the ease of management are securable by making the temperature of the process liquid 8 into 80 degrees C or less, More preferably, 60 degrees C or less.

  Furthermore, a water level meter 17 for measuring the water level of the staying tank 11a is provided in the staying tank 11a, and a water supply source for supplying a solvent (for example, water) into the staying tank 11a on the staying tank 11a. 15 is provided. Each of the water level gauge 17 and the water supply source 15 is electrically connected to the water level control device 16. When the water level control device 16 detects that the water level of the staying tank 11a is low, it supplies water from the water supply source 15 to the staying tank 11a. As a result, the water level of the retention tanks 11a to 11c can be kept constant.

  In the present embodiment, a processed sample is processed by the following method using the lapping apparatus 1 described above.

  First, a machining liquid 8 containing particles that cause a tribochemical reaction in the machining sample 7 is supplied onto the grindstones 2a and 3a. The hardness of the particles in the machining liquid 8 is equal to or lower than the hardness of the machining sample 7, and the particles in the machining liquid 8 are made of, for example, silicon oxide, iron oxide, chromium oxide, or titanium oxide. Thus, the tribochemical reaction of the processed sample can be promoted, and the workpiece is mechanically removed by the particles. The solvent of the machining fluid 8 is, for example, an emulsion (emulsion) type water-soluble cutting oil, a solution (solid solution) type water-soluble cutting oil, water, or an aqueous solution. Is 9 or more and 12 or less. Thereby, the processing liquid 8 serves as a lapping liquid and also serves as a dispersion solvent for the particles. Moreover, clogging of the grindstones 2a and 3a can be prevented. Furthermore, the particles can be uniformly dispersed in the machining liquid 8. The “emulsion type” is a liquid in which the water-soluble cutting oil component can be dispersed in a colloidal form, and the “solution type” means that the water-soluble cutting oil component is dissolved and present. It means a liquid that can be made. For adjusting the pH of the working liquid 8, inorganic bases such as alkali metal salts, alkaline earth metal salts, and ammonium salts, and organic bases such as ethylenediamine and ethanolamine can be used.

  The addition amount of the particles is preferably 0.2% by mass or more and 15% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less. By making the addition amount of the particles 0.2 mass%, a tribochemical reaction easily occurs in the processed sample 7. By making the addition amount of the particles 15% by mass or less, it is possible to prevent the particles from interfering with mechanical removal of the processed sample 7 by the grindstones 2a and 3a, and to suppress a decrease in the processing speed. be able to.

  The average particle size of the particles is preferably 3 μm or less, and more preferably 1 μm or less. By setting the average particle size of the particles to 3 μm or less, the frequency of contact with the processed sample 7 can be increased, and the reaction efficiency of the tribochemical reaction per unit deposition of the particles can be increased. Further, the particles are less likely to precipitate in the solvent, and the dispersed state in the solvent can be maintained. Thereby, the production | generation efficiency of the processed product in the surface of the process sample 7 can be improved, and a processing speed can fully be improved. Moreover, it is preferable that the particle size of the particles is equal to or less than the particle size of the grindstones 2a and 3a. By making the particle size of the particles equal to or less than the particle size of the grindstones 2a and 3a, the particles can be prevented from obstructing the mechanical removal of the processed sample 7 by the grindstones 2a and 3a, and the processing speed is reduced. Can be suppressed.

The processing liquid 8 that has flowed out between the processed sample 7 and the grindstones 2a and 3a contains foreign substances such as polishing powder and dropped abrasive grains. The machining liquid 8 containing foreign matter is supplied to the bottom of the retention tank 11 a of the tank 6 through the drain pipe 5. By supplying the working liquid 8 to the staying tank 11a, the working liquid 8 in the staying tank 11a overflows from the upper part of the partition wall that separates the staying tank 11a and the staying tank 11b, and flows into the staying tank 11b. At this time, since the particle size of the foreign matter contained in the processing liquid 8 supplied to the staying tank 11a is larger than the particle size of the particles, the settling speed of the foreign matter contained in the staying tank 11b is compared with the settling speed of the particles. And fast. For this reason, the foreign material contained in the machining liquid 8 is retained in the retention tank 11.
Although it stays at the bottom of a and becomes difficult to flow into the retention tank 11b, the concentration of the particles contained in the processing liquid 8 flowing from the retention tank 11a into the retention tank 11b is hardly changed. Thereby, the foreign material contained in the machining liquid 8 is removed. Similarly, the foreign matter contained in the machining liquid 8 is further removed by providing the staying tank 11c. Then, the machining liquid 8 from which only the foreign matters have been removed is supplied again via the supply pipe 4.

  In the present embodiment, the case where the number of staying tanks is three (three stages) is shown, but the number of staying tanks is arbitrary, and two (two stages) or more (eight stages) or less. Preferably there is. By setting the number to 2 or more, foreign substances having a relatively large particle size can be precipitated, and by setting the number to 8 or less, it is possible to prevent the particles themselves from being settled and the concentration of the particles from being lowered.

  According to the lapping method and the processing apparatus 1 of the present embodiment, a tribochemical reaction occurs on the friction surface of the processed sample 7 and a reaction product of the processed sample 7 is generated. The grindstones 2a and 3a mechanically remove the surface of the processed sample 7 at the same time as removing the reaction product, thereby creating a new surface of the processed sample 7. Then, a tribochemical reaction occurs again on the surface of the new processed sample 7, and a reaction product of the processed sample 7 is generated. In the present embodiment, such an action repeatedly occurs. As a result, since the surface of the processed sample 7 can be removed chemically and mechanically, the lapping processing efficiency can be improved.

  Moreover, according to the lapping method and the processing apparatus 1 of the present embodiment, since the grindstones 2a and 3a do not need to be made of a ceramic sintered body, it is necessary to go through a complicated production process in order to produce the grindstone. There are no restrictions on the size and shape of the grindstone. The processing liquid 8 can be easily obtained by adding particles that cause a tribochemical reaction to the processing sample 7 to the liquid. Therefore, the wrapping efficiency can be improved. Moreover, deterioration of a grindstone can be suppressed.

  In addition, according to the lapping processing apparatus 1 of the present embodiment, the particle size of the foreign matter contained in the processing liquid 8 supplied to the retention tank 11a is such that the processing sample 7 causes a tribochemical reaction. Therefore, the sedimentation rate of the foreign matter is faster than the sedimentation rate of the particles. Therefore, the foreign matter stays at the bottom of the staying tank 11a and hardly flows into the staying tanks 11b and 11c. However, the particles are uniformly dispersed in the staying tank 11a and have the same concentration as the staying tank 11c. Flow into. As a result, the machining liquid 8 from which only the foreign matter is removed can be supplied again, and the machining liquid 8 can be recycled and used. In particular, if the particles are removed using a conventional filter, the particles are trapped in the filter and the concentration of the particles in the processing liquid 8 is reduced, or the filter is frequently clogged by the particles. Problem arises.

In this example, the influence of the grindstone particle size and the machining fluid on the lapping processing speed was examined. Specifically, a lapping process was performed on a processed sample made of nitride ceramics using the lapping apparatus shown in FIG. As a processed sample, a spherical sample having a diameter of 1/4 inch was used. A diamond grindstone was used as the grindstone, and lapping was performed by changing the particle size in the range of No. 170 to No. 800. The grindstone was attached to both of the two surface plates, and a plurality of grooves concentric with the rotating shaft on which the work piece rolls were provided on the grindstone surface. In Comparative Example A1 and Inventive Example A2, diamond of No. 170 is used, and in Comparative Example B1 and Inventive Example B2, diamond of No. 400 is used, Comparative Example C1, Comparative Example C2, and Inventive Example In C3 to C9, diamond having a particle size of 800 was used. In Comparative Example D1, a processing sample was lapped with a surface plate (casting surface plate) without using a grindstone. A resin bond was used as a bonding material between the grindstone and the surface plate. Moreover, the following were used as a processing liquid.

  Comparative Example A1, Comparative Example B1, and Comparative Example C1: A white kerosene-based oily working fluid that is a conventional working fluid was used.

  Comparative Example C2: An emulsion type water-soluble cutting oil was used as it was without mixing the particles.

  Invention Example A2, Invention Example B2, Invention Example C3, and Comparative Example D1: A colloidal silica aqueous solution (manufactured by Fujimi Incorporated, to which emulsion type water-soluble cutting oil and 2% by mass of silica fine particles are added. A mixed processing liquid (hereinafter referred to as an emulsion mixed processing liquid) mixed with COMPOLAD 50) was used.

  Invention Example C4 to Invention Example C7: Emulsion-type water-soluble cutting oil with 2% by mass of silicon oxide (Cai Kasei, Nanotek), iron oxide (Toda Kogyo, 100ED), chromium oxide (Nihon Kagaku Kogyo, A working fluid in which chromex S-1) or titanium oxide (Ci Kasei, Nanotek) was dispersed was used.

  Invention Example C8: A mixed working fluid (hereinafter referred to as a solution mixed working fluid) in which a solution-type water-soluble cutting oil and a colloidal silica aqueous solution to which 2% by mass of silica fine particles were added was mixed.

  Invention Example C9: An aqueous colloidal silica solution to which silica fine particles corresponding to 2% by mass were added was used.

  Table 1 shows the processing speed ratio of lapping processing for each sample with respect to a comparative example having the same grindstone particle size.

  Referring to Table 1, the processing speed of the example of the present invention is greatly improved as compared with the processing speed of the comparative example, particularly when a fine grindstone of No. 400 or more is used. On the other hand, in Comparative Example D1, the processing speed is low despite using the emulsion mixed processing liquid. Therefore, the improvement of the processing speed of the example of the present invention is considered to be due to the synergistic effect of the hardness of the grindstone and the processing liquid.

In addition, the present invention example C3 and the present invention example C9 are compared, and the present invention example C3 using the emulsion mixed processing liquid is improved in the present invention example C9 using the colloidal silica aqueous solution alone. The improvement of the processing speed is larger. On the other hand, compared with Comparative Example C2 and Invention Example C3, the processing speed of Comparative Example C2 using the emulsion-type water-soluble cutting oil alone is not so improved. The improvement is thought to be due to the synergistic effect of the emulsion-type water-soluble cutting oil and colloidal silica.

  Further, comparing Comparative Example C1 with Invention Example C4 to Invention Example C7, the processing speeds of Invention Example C4 to Invention Example C7 are all greatly improved to about 2.9 times to 3.1 times. ing. From this, it can be seen that the processing speed can be improved by adding predetermined oxide particles to the emulsion type aqueous solution instead of using the emulsion mixed processing liquid.

  Further, comparing the comparative example C1 and the inventive example C8, the processing speed of the inventive example C8 is greatly improved to 3.22 times. From this, it can be seen that the processing speed is improved by using the solution mixed processing fluid instead of using the emulsion mixed processing fluid.

  In this example, a working fluid different from the working fluid used in Example 1 was used, and the influence of the grindstone particle size and the working fluid on the lapping processing speed was examined. Specifically, using the same lapping method and processing apparatus as in Example 1, a processing sample made of nitride ceramics was lapped. As a grindstone, diamond of No. 170 particle size is used in Comparative Example E1 and Invention Example E2, and diamond of No. 400 particle size is used in Comparative Example F1 and Invention Example F2, and Comparative Example G1 and Invention Example G2 are used. In ~ G6, diamonds with a particle size of 800 were used. In Comparative Example H1, a processing sample was lapped with a surface plate (casting surface plate) without using a grindstone. The followings were used as the working fluid of this example.

  Comparative Example E1, Comparative Example F1, and Comparative Example G1: A white kerosene-based oily working fluid that is a conventional working fluid was used (same as Comparative Example A1, Comparative Example B1, and Comparative Example C1 of Example 1). .

  Invention Example E2, Invention Example F2, Invention Example G2, and Comparative Example H1: A colloidal silica aqueous solution to which silica fine particles corresponding to 2 mass% were added was prepared, and diluted with water to adjust the pH of the colloidal silica aqueous solution to pH 11. Adjusted and used.

  Invention Example G3 to Invention Example G6: A working fluid in which 2% by mass of silicon oxide, iron oxide, chromium oxide, or titanium oxide was dispersed in a KOH aqueous solution having a concentration of 0.001 mol / l was used.

  Table 2 shows the processing speed ratio of lapping processing for each sample with respect to a comparative example having the same grindstone particle size.

  Referring to Table 2, the processing speed of the example of the present invention is greatly improved as compared with the processing speed of the comparative example, particularly when a fine grindstone of No. 400 or more is used. On the other hand, in Comparative Example H1, the processing speed is low although the colloidal silica aqueous solution is used. Therefore, it is considered that the improvement in the processing speed in the example of the present invention is due to the synergistic effect of the hardness of the grindstone and the processing liquid.

  Further, comparing the comparative example G1 with the inventive example G3 to the inventive example G6, the processing speeds of the inventive example G3 to the inventive example G6 are greatly improved to about 1.8 to 2 times. . From this, it can be seen that the processing speed is improved even when predetermined oxide particles are added to the aqueous solution instead of using the colloidal silica aqueous solution.

In addition, when performing the lapping process of the inventive examples G2 to G6, the pH of the processing liquid is changed in the range of 2 to 13, and in the processing liquid of particles made of silicon oxide, iron oxide, chromium oxide, or titanium oxide. The dispersion state of was evaluated. Specifically, the above particles were added to an aqueous KOH solution, stirred for 10 minutes with a beaker, and observed for 5 hours. As a result, at pH 5 to pH 9, particles were aggregated and settled and difficult to redisperse. However, at pH 2 to pH5 and pH9 to pH13, the particles were kept in a dispersed state or redispersed even if precipitated. It was possible.

  In this example, the influence of the temperature of the working fluid on the processing speed of the lapping processing was examined. Specifically, a processing sample made of nitride ceramics was lapped using the same method as in Example 1. As the grindstone, diamond having a grain size of 800 was used, and as a bonding material between the grindstone and the lower surface plate, resin bond was used. Further, as the processing liquid, an emulsion-type water-soluble cutting oil and a colloidal silica aqueous solution (processing liquid of the present invention example C3) to which 2% by mass of silica fine particles were added were used. About the temperature of the process liquid, it changed in the range of 10 to 80 degreeC, and measured the processing speed in each temperature. FIG. 3 shows the relationship between the working fluid temperature and the lapping process speed ratio. The processing speed ratio in FIG. 3 is a value when the processing speed is 1 when the temperature of the processing liquid is 20 ° C. (room temperature).

  Referring to FIG. 3, the processing speed is improved as the temperature of the processing liquid rises. From this result, it can be seen that the machining efficiency is further improved by raising the temperature of the working fluid above room temperature.

  The embodiments and examples disclosed above are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

  The present invention is suitable for processing silicon nitride ceramic spheres and sialon ceramic spheres used for bearing rolling elements and ball valves.

  DESCRIPTION OF SYMBOLS 1 Lapping apparatus, 2, 3 Surface plate, 2a, 3a Grinding stone (groove), 4 Supply pipe, 5 Drain pipe, 6 Tank, 7 Process sample, 8 Process liquid, 9,10 Chute, 11a-11c Residence tank, 12 Temperature control device, 13 thermometer, 14 pump, 14a, 14b heater, 15 water supply source, 16 water level control device, 17 water level meter.

Claims (10)

A spherical lapping method for lapping a surface of a workpiece made of silicon nitride ceramics or sialon ceramics with an abrasive material,
The abrasive material includes abrasive grains that are harder than the workpiece,
A lapping method, comprising: supplying a liquid containing particles that cause a tribochemical reaction to the workpiece between the workpiece and the polishing material to perform lapping.   The lapping method according to claim 1, wherein the liquid is an emulsion type water-soluble cutting oil or a solution type water-soluble cutting oil.   The lapping method according to claim 1, wherein the liquid is water or an aqueous solution, and the pH of the liquid is 9 or more and 12 or less.   The lapping method according to any one of claims 1 to 3, wherein the hardness of the particles is equal to or less than the hardness of the workpiece.   The lapping method according to any one of claims 1 to 4, wherein the particles are made of an oxide of at least one element selected from the group consisting of silicon, iron, chromium, and titanium.   The abrasive grain is made of at least one material selected from the group consisting of diamond, CBN, and boron carbide, and the grain size of the abrasive grain is smaller than No. 400. A wrapping method according to crab.   A pair of coaxially arranged discs having the abrasive material attached to at least one of the discs, wherein the sphere is sandwiched between the opposing abrasive material surfaces and the sphere is polished by rotating one of the discs. The lapping method according to any one of claims 1 to 6.   The lapping method according to any one of claims 1 to 7, wherein the liquid has a temperature higher than room temperature and not higher than 80 ° C. A lapping apparatus for lapping a surface of a workpiece made of silicon nitride ceramics or sialon ceramics with an abrasive material,
The abrasive material containing abrasive grains having a hardness higher than that of the workpiece;
A supply unit for supplying a liquid containing particles that cause a tribochemical reaction to the workpiece between the workpiece and the polishing material;
A drainage section for discharging the liquid containing the workpiece from the polishing material;
A housing having a first tank and a second tank;
The liquid discharged from the drainage unit is supplied to the first tank, the liquid overflowing from the first tank flows into the second tank, and the liquid in the second tank is supplied to the supply unit A lapping apparatus characterized by being supplied from:   The lapping apparatus according to claim 9, further comprising a control device for controlling a temperature of the liquid supplied from the supply unit.

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