Method for manufacturing a polishing tool and a polishing tool

Abstract

To provide a manufacturing method of a polishing tool usable for polishing the surface of a metal or a ceramic; and to provide a polishing tool.SOLUTION: A manufacturing method of a polishing tool 1 includes a molding step for supplying glass particles into a mold in which the shape of a gripping part 4 is set, and molding the glass particles into a desired shape, and a firing step for heating the glass particle at a temperature over a softening point and below a melting point of the glass particle, after the molding step, and finishing heating in the state where bubbles are dispersed in gaps between the glass particles and remain there, to thereby form a glass block (tool body 2) as the polishing tool 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a polishing tool used for polishing the surface of metal or ceramics and a polishing tool.

Background Art

[0002] When processing the surface of metal or ceramics, minute irregularities and minute protrusions called burrs may occur on the surface. As a polishing stone used to remove such irregularities and burrs from the surface, an Arkansas stone is known. The Arkansas stone is used, for example, in a processing apparatus for processing a workpiece such as a semiconductor wafer to rub and remove burrs and attached chips on the holding surface of a chuck table for holding the workpiece, or for cleaning by manually polishing a table base that supports the chuck table (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The Arkansas stone is a natural oilstone produced in the state of Arkansas in the United States of America. Since the Arkansas stone is a natural product, it is expensive and precious, and its properties are likely to be non-uniform and there are large individual differences. Therefore, there is a demand for a polishing stone that can be used as a substitute for the Arkansas stone and a high-quality polishing stone with less variation than the Arkansas stone.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a method for manufacturing a new polishing tool and a polishing tool that can be used for polishing the surface of metal or ceramics.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a method for manufacturing a polishing tool according to the present invention is a method for manufacturing a polishing tool having a gripping portion, comprising: a forming step of supplying glass grains to a mold having a shape of the gripping portion set therein and forming the glass grains into a desired shape; and a firing step of heating the glass grains at a temperature exceeding the softening point and less than the melting point of the glass grains after the forming step, and ending the heating in a state where bubbles are dispersed and remain in the gaps between the glass grains to form a glass block serving as a polishing tool. 、The glass particles shall account for 90% by volume or more of the whole, have a particle size of 50 μm or more and 150 μm or less, and the porosity of the glass block after the firing step shall be 2% or more and 8% or less. That's what it is.

[0007] After the firing step, a polishing step may be provided in which a working surface that contacts and polishes the object to be polished is polished so that the surface roughness (Ra) is 0.2 μm or more and 1.5 μm or less.

[0008] The material of the glass particles is soda glass, and in the firing step, the glass particles may be heated at a temperature higher than 720 °C and lower than 1000 °C. Also, the material of the glass particles is feldspar, and in the firing step, the glass particles may be heated at a temperature higher than 900 °C and lower than 1350 °C. Also, the material of the glass particles is borosilicate glass, and in the firing step, the glass particles may be heated at a temperature higher than 820 °C and lower than 1250 °C.

[0009] Further, in order to solve the above-described problems and achieve the object, a polishing tool according to the present invention is a polishing tool for polishing a surface of metal or ceramics, comprising a glass block having a surface roughness (Ra) of 0.2 μm or more and 1.5 μm or less, a porosity of 2% or more and 8% or less, and a gripping portion formed therein. The glass block is formed by dispersing and remaining bubbles in the gaps between the glass particles. The glass particles account for 90% by volume or more of the whole and have a particle size of 50 μm or more and 150 μm or less. 。

[0010] The material of the glass particles may be soda glass, feldspar or borosilicate glass. Also, The polishing tool may not contain abrasive grains.

Advantages of the Invention

[0011] The present invention can be used for polishing the surfaces of metals and ceramics.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] A mode for carrying out the present invention (embodiment) will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0014] 〔Embodiment〕 A method for manufacturing a polishing tool and the polishing tool 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a polishing tool 1 which is an example of a polishing tool according to an embodiment. FIG. 2 is a flowchart showing an example of a processing procedure of a method for manufacturing a polishing tool according to an embodiment. FIG. 3 is a cross-sectional view for explaining the molding step 1001 of FIG. 2. FIG. 4 is a cross-sectional view showing a mold 10 which is an example of a mold used in the molding step 1001 of FIG. 2. FIG. 5 is a cross-sectional view for explaining the firing step 1002 of FIG. 2. FIG. 6 is a perspective view for explaining the polishing step 1003 of FIG. 2. FIG. 7 is a cross-sectional view for explaining the polishing step 1003 of FIG. 2.

[0015] The polishing tool 1 according to the embodiment is manufactured by the method for manufacturing a polishing tool according to the embodiment shown in FIG. 2, and as shown in FIG. 1, includes a tool body 2, a working surface 3, and a gripping portion 4. In this embodiment, the object to be polished by the polishing tool 1 is, for example, the surface of metal or ceramics, and specifically, the holding surface of a chuck table that holds a workpiece in a processing apparatus for processing a workpiece such as a semiconductor wafer, or the surface of a table base that supports the chuck table.

[0016] In this embodiment, the tool body 2 is a glass block generally formed in a rectangular shape as shown in FIG. 1. The tool body 2 has pores inside, and in this embodiment, the porosity, which is the ratio of the volume occupied by the pores in the total volume of the tool body 2, is 2% or more and 8% or less. Therefore, in the tool body 2, the pores are appropriately sized and appropriately dispersed inside. Since the porosity of the tool body 2 is 2% or more, the lubricating fluid used when polishing the object to be polished by the polishing tool 1 can be appropriately retained. Since the porosity of the tool body 2 is 8% or less, the pores are appropriately separated inside the tool body 2, and the lubricating fluid does not penetrate excessively into the tool body 2, and an appropriate amount of lubricating fluid can remain on the surface (working surface 3) and act easily.

[0017] Note that when the porosity is less than 2%, it may be difficult to appropriately retain the lubricating fluid. Also, when the porosity exceeds 8%, the pores are connected to each other inside, so the lubricating fluid easily penetrates inside, and there is a possibility that an appropriate amount of lubricating fluid will not remain on the surface and will not act easily. When the porosity exceeds 8%, furthermore, the pores exposed on the working surface are likely to hit burrs or the like of the object to be polished by the polishing tool, which may easily reduce the processing quality of the polishing tool.

[0018] The working surface 3 is a surface that contacts and polishes the object to be polished by the polishing tool 1, and is formed in parallel on a pair of surfaces (the upper surface and the bottom surface in FIG. 1) of the tool body 2 that are in a front-back relationship with each other. In this embodiment, the working surface 3 is formed with a surface roughness (Ra) of 0.2 μm or more and 1.5 μm or less. Here, the surface roughness (Ra) is the arithmetic mean height (Ra) of the profile curve elements defined based on the surface roughness of Japanese Industrial Standards (JIS B 0601:1994, JIS B 0031:1994), and is the average value of the absolute values of the deviations from the mean line of the height in the reference length to the roughness curve. Also, since the polishing tool 1 does not contain abrasive grains, the working surface 3 has extremely high flatness, and there is no risk of damage such as scratches on the surface to be polished even when polishing an object to be polished such as metal or ceramics.

[0019] The gripping portion 4 is a portion that is gripped by an operator (human) who polishes an object to be polished with the polishing tool 1, and is formed on a pair of surfaces (the side surfaces on the front left side and the rear right side in FIG. 1) of the tool body 2 that are in a front-back relationship with each other other than the working surface 3, in a shape that is easy to grip with the finger pad side of the operator's hand (either bare hand or through a protective tool such as a glove). Specifically, the gripping portion 4 has irregularities and preferably has a curved surface. The irregularities of the gripping portion 4 are formed, for example, in a shape that provides a frictional force between the finger pad side of the operator's hand or a shape that catches on the finger pad side of the operator's hand, enabling the operator to grip the polishing tool 1 more firmly by gripping the gripping portion 4 with the finger pad side of the hand. The curved surface of the gripping portion 4 is formed, for example, as shown in FIG. 1, extending in a direction perpendicular to the working surface 3 and corresponding to a concave curved surface that intersects the direction in which the finger extends on the finger pad side of the operator's hand. When the operator grips the gripping portion 4 with the finger pad side of the hand, the convex curved surface on the finger pad side of the operator's hand and this concave curved surface come into contact so as to be generally fitted together, enabling the polishing tool 1 to be gripped more firmly and enabling the object to be polished to be stably polished with an appropriate pressure on the working surface 3.

[0020] Next, this specification will describe the operation of the method for manufacturing a polishing tool according to an embodiment with reference to the drawings. The method for manufacturing a polishing tool according to an embodiment is a method for manufacturing the polishing tool 1 according to the embodiment shown in FIG. 1, and as shown in FIG. 2, it includes a molding step 1001, a firing step 1002, and a polishing step 1003.

[0021] The molding step 1001 is a step of supplying glass grains 100 to a mold 10 in which the shape of the gripping portion 4 is set and molding them into a desired shape, as shown in FIG. 3. Here, the mold 10 used in the molding step 1001 has sufficient heat resistance in the high-temperature environment formed in the firing step 1002 described later, and moreover, it is made of a material that does not chemically react with the glass grains 100 and does not connect to the glass grains 100 in this environment. Further, as shown in FIG. 4, the mold 10 used in the molding step 1001 has a concave mold surface 11 corresponding to the outer surface shape of the polishing tool 1 having the working surface 3 and the gripping portion 4. That is, the mold surface 11 of the mold 10 has a gripping portion corresponding curved surface 14 corresponding to the gripping portion 4.

[0022] In the molding step 1001, specifically, the glass grains 100 are supplied from a predetermined container 20 to the mold 10, and for example, the mold 10 supplied with the glass grains 100 is vibrated, etc., so that the upper surface of the glass grains 100 supplied to the mold 10 is flattened and the extra space between the glass grains 100 is removed to homogenize the glass grains 100. As a result, the outer surface side of the glass grains 100 is formed into the outer surface shape of the polishing tool 1 having the working surface 3 and the gripping portion 4 according to the shape of the concave mold surface 11.

[0023] The glass particles 100 supplied in the forming step 1001 are made of, for example, soda glass, feldspar, borosilicate glass, or the like. Ninety volume percent or more of the glass particles 100 are spherical or nearly spherical, that is, the sphericity is equal to or less than a predetermined threshold value. A part of the glass particles 100 may not be spherical or nearly spherical. Also, ninety volume percent or more of the glass particles 100 have a particle size of 50 μm or more and 150 μm or less. A part of the glass particles 100 may have a particle size outside the range of 50 μm or more and 150 μm or less. Note that known methods such as geometric diameter and equivalent diameter are used to represent the particle size of the glass particles 100. Examples of the geometric diameter include the Feret diameter, the maximum diameter in a fixed direction (i.e., the Krummbein diameter), the Martin diameter, and the sieve diameter. Examples of the equivalent diameter include the equivalent circle diameter of the projected area (i.e., the Heywood diameter), the equivalent sphere diameter of the equal surface area, the equivalent sphere diameter of the equal volume, the Stokes diameter, and the light scattering diameter.

[0024] In addition, when the glass particles contain a certain volume (10% by volume or more) of particles that are not spherical or nearly spherical, gaps of irregular shapes are formed between the glass particles due to these glass particles that deviate significantly from the spherical shape. As a result, during subsequent heating and firing, it may become difficult to form pores of appropriate size and appropriately dispersed inside the tool body. Also, when the glass particles contain a certain volume (10% by volume or more) of particles with a particle size larger than 150 μm, gaps between the glass particles are formed due to these large glass particles. As a result, during subsequent heating and firing, adjacent pores inside the tool body may connect to each other, making it difficult to form pores of appropriate size and appropriately dispersed inside the tool body. Thus, if pores of appropriate size and appropriately dispersed are not formed inside the tool body during subsequent heating and firing, the finally manufactured polishing tool may have difficulty appropriately retaining the lubricating fluid used when polishing the object to be polished, or conversely, the lubricating fluid may penetrate excessively inside the tool body and an insufficient amount of the lubricating fluid may remain on the surface. Also, when the glass particles contain a certain volume (10% by volume or more) of particles with a particle size less than 50 μm, it becomes difficult to handle the glass particles during the molding step or the like, and there is a risk that the glass particles will not fit properly inside the mold.

[0025] As shown in FIG. 5, the firing step 1002 is a step of heating the glass particles 100 at a temperature exceeding the softening point and less than the melting point of the glass particles 100 after the molding step 1001, and then ending the heating with the bubbles dispersed and remaining in the gaps between the glass particles 100 to form a glass block that becomes the polishing tool 1. In the firing step 1002, first, after closing the upper part where the glass particles 100 were supplied in the molding step 1001 of the mold 10 with the lid body 12, the mold 10 and the lid body 12 together with the glass particles 100 are placed inside the heating furnace 30. Here, the lid body 12 is formed of a material having the same properties as the aforementioned mold 10, for example, the same material as the mold 10.

[0026] In the firing step 1002, after putting the glass particles 100 together with the mold 10 and the lid 12 into the heating furnace 30, the heating furnace 30 heats the glass particles 100 together with the mold 10 and the lid 12 at a temperature exceeding the softening point and less than the melting point of the glass particles 100 for a predetermined time to perform firing. Here, the softening point of the glass particles 100 is the temperature at which the glass particles 100 start to deform when the temperature is raised. The softening point of the glass particles 100 varies depending on properties such as the material and structure of the glass particles 100, and is a temperature lower than the melting point. In the firing step 1002, by this heating and firing, the glass particles 100 soften and come into contact with adjacent glass particles 100, so that the adjacent glass particles 100 are partially connected and integrated as a whole, and a glass block of the tool body 2 having a shape corresponding to the concave mold surface 11 of the mold 10, with the working surface 3 and the gripping portion 4, is formed.

[0027] In the firing step 1002, also, by this heating and firing, the spaces between the glass particles 100 are appropriately separated by the glass particles 100 that are connected to each other, and pores of appropriate size and appropriately dispersed are formed inside the tool body 2. As a result, the porosity of the glass block of the tool body 2 becomes 2% or more and 8% or less. In the firing step 1002, also, abrasive grains are not intentionally supplied or added to the mold 10 in the molding step 1001, and only the glass particles 100 supplied in the molding step 1001 are heated and fired. Thus, the glass block of the tool body 2 formed thereby does not contain abrasive grains.

[0028] In the firing step 1002, specifically, when the material of the glass particles 100 is soda glass, the glass particles 100 are heated at a temperature higher than 720°C and lower than 1000°C. When the glass particles 100 are feldspar, the glass particles 100 are heated at a temperature higher than 900°C and lower than 1350°C. Further, when the glass particles 100 are borosilicate glass, the glass particles 100 are heated at a temperature higher than 820°C and lower than 1250°C.

[0029] When the glass particles are heated at a temperature below the softening point, the glass particles are not sufficiently deformed, making it difficult to connect and integrate the glass particles, which may make it difficult to form the glass block of the tool body. When the glass particles are heated at a temperature above the melting point, the space between the glass particles may be filled with the molten glass particles, which may make it difficult to form pores with appropriate size and appropriate dispersion.

[0030] In the firing step 1002, the predetermined time for heating the glass particles 100 by the heating furnace 30 is, for example, 1 hour or more and 2 hours or less in this embodiment. When the heating time of the glass particles is too short, the glass particles are not sufficiently deformed, making it difficult to connect and integrate the glass particles, which may make it difficult to form the glass block of the tool body. When the heating time of the glass particles is too long, the glass particles are excessively deformed, and the space between the glass particles is filled with the excessively deformed glass particles, which may make it difficult to form pores with appropriate size and appropriate dispersion.

[0031] In the firing step 1002, the porosity of the glass block of the tool body 2 is determined based on the particle size of the glass particles 100, the heating temperature, and the heating time. Therefore, in the firing step 1002, by strictly controlling the particle size of the glass particles 100 supplied in the forming step 1001, the heating temperature in the firing step 1002, and the heating time in the firing step 1002, it is possible to reduce the variation in the porosity of the glass block of the tool body 2 compared to the conventional natural alkanthus grindstone.

[0032] In the firing step 1002, after heating and firing the glass grains 100, the glass grains 100 are taken out of the heating furnace 30 together with the mold 10 and the lid 12, the lid 12 is opened, and the glass block of the tool body 2 formed by firing the glass grains 100 is taken out from the mold 10. In the present embodiment, the mold 10 is configured to be assembled and disassembled, and the glass block of the tool body 2 formed in the firing step 1002 is taken out by disassembling the mold 10. However, the present invention is not limited thereto, and the mold 10 may be destroyed to take out the glass block of the tool body 2 formed in the firing step 1002.

[0033] The glass block of the tool body 2 taken out here has a shape corresponding to the concave mold surface 11 of the mold 10, that is, the working surface 3 and the gripping portion 4 are formed, the internal porosity is 2% or more and 8% or less, and it does not contain abrasive grains. Here, one working surface 3 of the taken-out glass block of the tool body 2 is formed according to the bottom surface of the concave mold surface 11 of the mold 10, and the other working surface 3 is formed based on the upper surface of the glass grains 100 flattened in the forming step 1001. By performing the polishing step 1003 described later to appropriately polish the pair of working surfaces 3 to be flat and parallel to each other, it can be used as the polishing tool 1.

[0034] As shown in FIGS. 6 and 7, the polishing step 1003 is a step of obtaining the polishing tool 1 according to the embodiment by polishing the working surface 3 that contacts and polishes the object to be polished after the firing step 1002 so that the surface roughness (Ra) is 0.2 μm or more and 1.5 μm or less. In the polishing step 1003, specifically, first, the side surface including the gripping portion 4 of the glass block of the tool body 2 taken out after the firing step 1002 is held by a carrier 41 having the same thickness as or slightly thinner than the glass block of the tool body 2, so that the glass block of the tool body 2 is held in a state where both working surfaces 3 are exposed. In the polishing step 1003, since the glass block of the tool body 2 has the gripping portion 4 in this way, it is easy to stably hold the glass block of the tool body 2 with the carrier 41.

[0035] In the grinding step 1003, also, a pair of lapping plates 44 are prepared, each having an abrasive stone 43 laid and fixed on one surface of a disk-shaped lapping platen 42 having a large surface that sufficiently covers the working surface 3 of the glass block of the tool body 2. The pair of lapping plates 44 are rotated in opposite directions around the axis with the sides where the abrasive stones 43 are fixed facing and contacting each other, thereby grinding the abrasive stones 43 together to make the grinding surfaces by the abrasive stones 43 parallel to each other, that is, performing parallelization of the grinding surfaces of the so-called lapping plates 44.

[0036] In the grinding step 1003, and as shown in FIGS. 6 and 7, a carrier 41 holding the glass block of the tool body 2 is disposed between the two lapping plates 44 whose grinding surfaces have been parallelized, and the two lapping plates 44 are rotated in opposite directions around the axis, whereby a pair of working surfaces 3 of the glass block of the tool body 2 held by the carrier 41 are ground by the abrasive stones 43 of the grinding surfaces of the two lapping plates 44 respectively, so that the pair of working surfaces 3 of the glass block of the tool body 2 can be made flat and parallel to each other, and the undulation of the glass block of the tool body 2 can be removed. In the grinding step 1003, in this way, by grinding the pair of working surfaces 3 of the glass block of the tool body 2 formed by performing the forming step 1001 and the firing step 1002, the grinding tool 1 according to the embodiment shown in FIG. 1 is obtained.

[0037] In the grinding step 1003, in the example shown in FIG. 6, four carriers 41 holding the glass blocks of three tool bodies 2 are disposed between a pair of lapping plates 44, and twelve glass blocks of the tool body 2 are ground at once. However, the present invention is not limited to this, and they may be ground one by one, or more may be ground at once.

[0038] In the polishing step 1003, the surface roughness (Ra) of the pair of working surfaces 3 after polishing is determined by the abrasive size of the abrasive grains 43 on the polishing surfaces of the two lapping and polishing plates 44 that polish the pair of working surfaces 3. Therefore, in the polishing step 1003, abrasive grains 43 with an abrasive size that makes the surface roughness (Ra) of the pair of working surfaces 3 after polishing 0.2 μm or more and 1.5 μm or less are used. Here, the abrasive size of the abrasive grains 43 refers to the size of the grain size of the abrasive grains 43, which is defined by the JIS standard "R6001: Grain Size of Grinding and Honing Abrasives". It is a parameter in which the number becomes smaller as the central particle size becomes larger and the number becomes larger as the central particle size becomes smaller. Specifically, the abrasive size of the abrasive grains 43 used in the polishing step 1003 is, for example, #360 (No. 360) or more and #2500 (No. 2500) or less. In the polishing step 1003, by strictly controlling the abrasive size of the abrasive grains 43, it is possible to reduce the variation in the surface roughness (Ra) of the working surface 3 compared to conventional natural Arkansas abrasive stones.

[0039] In the polishing step 1003, in the present embodiment, the pair of working surfaces 3 of the glass block of the tool body 2 are polished with two lapping and polishing plates 44, but the present invention is not limited to this, and any device capable of polishing the glass block may be used for polishing.

[0040] The polishing tool 1 according to the embodiment having the above configuration is formed of a glass block, similar to an Arkansas abrasive stone. Since the surface roughness (Ra) of the working surface 3 is 0.2 μm or more and 1.5 μm or less, it has the effect of being able to polish the surfaces of metals and ceramics, which are the objects to be polished, with the same quality and the same working feeling of the operator as when using an Arkansas abrasive stone. Further, in the polishing tool 1 according to the embodiment, since the pair of working surfaces 3 are formed flat and parallel to each other, it has the effect of omitting the operation of reforming and polishing the working surface after purchase and before use, which was necessary for conventional natural Arkansas abrasive stones supplied to the market as natural products.

[0041] In addition, since the polishing tool 1 according to the embodiment has a porosity of 2% or more and 8% or less, it can moderately hold the lubricating liquid, prevent the lubricating liquid from excessively penetrating inside, and leave the required amount of lubricating liquid on the working surface 3, thus achieving the effect of being able to polish the object to be polished in a state where it is easy to act.

[0042] In addition, since the polishing tool 1 according to the embodiment does not contain abrasive grains, the flatness of the working surface 3 is extremely high. Therefore, even when polishing an object to be polished such as metal or ceramics, it is possible to suppress the risk of damage such as scratches occurring on the surface to be polished, achieving the effect of being able to perform the polishing operation.

[0043] Conventional Arkansas grindstones are used together with a lubricating liquid, so there was a risk that the operator's hand would slip and the grindstone would fall and break. However, since the polishing tool 1 according to the embodiment has a gripping portion 4, the operator can grip the polishing tool 1 more firmly. By gripping firmly, the risk of the polishing tool 1 falling and breaking can be greatly reduced, achieving the effect of being able to stably polish the object to be polished with an appropriate pressure on the working surface 3.

[0044] In addition, in the manufacturing method of the polishing tool according to the embodiment having the above configuration, since the glass block of the polishing tool 1 is formed by heating and firing the glass grains 100 to integrate them, there is an effect that the polishing tool 1 having the same components as the Arkansas grindstone can be artificially obtained. Further, in the polishing step 1003 of the manufacturing method of the polishing tool according to the embodiment, the working surface 3 of the polishing tool 1 is polished with a grindstone 43 having a grindstone size such that the surface roughness (Ra) of the working surface 3 is 0.2 μm or more and 1.5 μm or less. Therefore, there is an effect that the polishing tool 1 having the same surface roughness as the Arkansas grindstone can be artificially obtained. In the manufacturing method of the polishing tool according to the embodiment, further, in the polishing step 1003, since the pair of working surfaces 3 are formed flat and parallel to each other, the operation of forming the working surface by polishing again after purchase and before use, which was necessary for the conventional Arkansas grindstone supplied as a natural product without further processing, can be omitted, and there is an effect that the polishing tool 1 can be artificially obtained. Also, in the manufacturing method of the polishing tool according to the embodiment, since the grindstone size of the grindstone 43 used in the polishing step 1003 is controlled to polish the working surface 3, there is an effect that the polishing tool 1 having less variation in surface roughness (Ra) than the conventional natural Arkansas grindstone can be artificially obtained.

[0045] In addition, in the manufacturing method of the polishing tool according to the embodiment, the particle size of the glass grains 100 supplied in the forming step 1001, the heating temperature in the firing step 1002, and the heating time in the firing step 1002 are controlled so that the porosity is 2% or more and 8% or less, and the glass grains 100 are heated and fired. Therefore, there is an effect that the polishing tool 1 having the same porosity as the Arkansas grindstone and further having less variation in porosity than the conventional natural Arkansas grindstone can be artificially obtained.

[0046] In addition, in the method for manufacturing a polishing tool according to the embodiment, without intentionally supplying and adding abrasive grains, only the glass grains 100 are heated and fired to obtain a glass block of the tool body 2 that serves as the base of the polishing tool 1. Therefore, it does not contain abrasive grains, the flatness of the working surface 3 is extremely high, and it is possible to artificially obtain a polishing tool 1 that can suppress the risk of damage such as scratches on the surface to be polished even when polishing an object to be polished such as metal or ceramics.

[0047] In the conventional Arkansas grindstone, since processing is difficult, it was difficult to form the gripping portion 4 of the polishing tool 1 according to the embodiment. However, in the method for manufacturing a polishing tool according to the embodiment, in the molding step 1001, the glass grains 100 are supplied to a mold 10 in which the shape of the gripping portion 4 is set, that is, a concave mold surface 11 having a gripping portion corresponding curved surface 14 corresponding to the gripping portion 4, and molded into a desired shape. Then, in the firing step 1002, the glass grains 100 are heated and fired. Therefore, an operator can grip the polishing tool 1 more firmly, and by gripping firmly, the risk of the polishing tool 1 falling and being damaged can be greatly reduced, and it is possible to artificially obtain a polishing tool 1 having a gripping portion 4 that can stably polish an object to be polished with an appropriate pressure on the working surface 3.

[0048] 〔Modification Example〕 The method for manufacturing a polishing tool and the polishing tool 1-2 according to a modification of the present invention will be described with reference to the drawings. FIG. 8 is a perspective view showing a polishing tool 1-2 which is an example of a polishing tool according to the modification. In FIG. 8, the same reference numerals are given to the same parts as in Embodiment 1, and the description thereof will be omitted.

[0049] As shown in FIG. 8, the polishing tool 1-2 according to the modified example is obtained by changing the gripping portion 4 to a gripping portion 4-2 in the polishing tool 1 according to the embodiment, and other configurations are the same as those in the embodiment. The gripping portion 4-2 in the modified example has a changed shape compared to the gripping portion 4 in the embodiment. Specifically, as shown in FIG. 1, the gripping portion 4 in the embodiment extends in a direction orthogonal to the working surface 3 and has a number of fingers (five locations) formed, while the gripping portion 4-2 in the modified example extends in the longitudinal direction of the working surface 3 and is formed one by one on a pair of side surfaces, as shown in FIG. 8. The curved surface of the gripping portion 4-2 is formed as a concave curved surface corresponding to a convex curved surface along the extending direction of the finger from the fingertip to the finger pad and up to the third joint of the operator's hand. By the operator gripping the gripping portion 4-2 with these parts of the hand, the convex curved surface of these parts of the operator's hand and this concave curved surface come into contact so as to be generally fitted together, enabling the polishing tool 1-2 to be gripped more firmly and stably polishing the object to be polished with an appropriate pressure on the working surface 3.

[0050] Next, this specification describes the operation of the manufacturing method of the polishing tool according to the modified example. The manufacturing method of the polishing tool according to the modified example is a method for manufacturing the polishing tool 1-2 according to the modified example shown in FIG. 8. In the manufacturing method of the polishing tool according to the embodiment, the mold 10 used is changed to one having a concave mold surface with a gripping portion corresponding curved surface corresponding to the outer surface shape of the polishing tool 1-2 having the working surface 3 and the gripping portion 4-2, that is, corresponding to the gripping portion 4-2, and other configurations are the same as those in the embodiment.

[0051] The polishing tool 1-2 according to the modified example having the above configuration is obtained by changing the gripping portion 4 to a gripping portion 4-2 with a different shape in the polishing tool 1 according to the embodiment, and other configurations are the same as those in the embodiment. Therefore, it exhibits the same operational effects as the embodiment. Also, the manufacturing method of the polishing tool according to the modified example is obtained by changing the mold 10 used in the manufacturing method of the polishing tool according to the embodiment to one corresponding to the outer surface shape of the polishing tool 1-2 having the gripping portion 4-2, and other configurations are the same as those in the embodiment. Therefore, it exhibits the same operational effects as the embodiment.

[0052] Note that the present invention is not limited to the above-described embodiments. That is, various modifications can be made and implemented without departing from the gist of the present invention. In the above embodiments and modification examples, the polishing tool 1 is manufactured by supplying the glass particles 100 to the mold 10 and heating and firing the entire mold 10. However, the present invention is not limited to this. After supplying the glass particles 100 to the mold 10, compression molding and demolding may be performed, followed by heating and firing to manufacture the polishing tool 1. Alternatively, a slurry obtained by mixing the glass particles 100 with a binder, an antifoaming agent, a dispersant, etc. may be poured into the mold 10 and dried to perform so-called casting molding. After demolding, the polishing tool 1 may be manufactured by heating and firing.

Explanation of Reference Numerals

[0053] 1,1-2 Polishing tool 2 Tool body 3 Working surface 4,4-2 Gripping portion 10 Mold 11 Mold surface 100 Glass particles

Claims

1. A method for manufacturing a polishing tool, comprising: a molding step of supplying glass grains to a mold having a set shape of a gripping portion and molding the glass grains into a desired shape; after the molding step, heating the glass grains at a temperature exceeding the softening point and less than the melting point of the glass grains, and ending the heating in a state where bubbles are dispersed and remaining in the gaps between the glass grains to form a glass block serving as a polishing tool; the glass grains being 90% by volume or more of the whole, having a particle size of 50 μm or more and 150 μm or less; A method for manufacturing a polishing tool having a gripping portion, wherein the porosity of the glass block after the firing step is 2% or more and 8% or less.

2. The method for manufacturing a polishing tool according to claim 1, further comprising a polishing step of polishing a working surface that contacts and polishes an object to be polished after the firing step, so that the surface roughness (Ra) is 0.2 μm or more and 1.5 μm or less.

3. The material of the glass grains is soda glass, and in the firing step, the glass grains are heated at a temperature higher than 720 ° C and lower than 1000 ° C. The method for manufacturing a polishing tool according to claim 1 or 2.

4. The material of the glass grains is feldspar, and in the firing step, the glass grains are heated at a temperature higher than 900 ° C and lower than 1350 ° C. The method for manufacturing a polishing tool according to claim 1 or 2.

5. The material of the glass grains is borosilicate glass, and in the firing step, the glass grains are heated at a temperature higher than 820 ° C and lower than 1250 ° C. The method for manufacturing a polishing tool according to claim 1 or 2.

6. A polishing tool for polishing a surface of metal or ceramics, comprising: a glass block having a surface roughness (Ra) of 0.2 μm or more and 1.5 μm or less, a porosity of 2% or more and 8% or less, and a gripping portion formed thereon; the glass block is formed by forming glass grains in a state where bubbles are dispersed and remaining in the gaps between the glass grains; the glass grains are 90% by volume or more of the whole, having a particle size of 50 μm or more and 150 μm or less.

7. The material of the glass grains is soda glass, feldspar or borosilicate glass. The polishing tool according to claim 6.

8. The polishing tool according to claim 6 or 7, characterized by not containing abrasive grains.

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