JP6076191B2 - Polishing tool manufacturing method and polishing tool manufacturing mold - Google Patents

Description

  The present invention relates to a method for manufacturing a polishing tool used for grinding or polishing an optical element such as a lens, a polishing tool, and a mold for manufacturing a polishing tool.

  When grinding or polishing an optical element having a rotationally symmetric shape such as a lens, a processing surface of a polishing tool (grinding stone) formed in a spherical shape (concave spherical shape or convex spherical shape) having a desired curvature is applied to the optical element. The surface to be processed is processed by abutting the processing surface, rotating the polishing tool and swinging the optical element.

  In such a rotating polishing tool, since the peripheral speed on the outer peripheral side is faster than the inner peripheral side of the processing surface, the distance rubbed in contact with the processing surface per unit time is longer on the outer peripheral side. As a result, wear of the processed surface on the outer peripheral side is faster than that on the inner peripheral side. As described above, since the ease of wear of the polishing tool is not uniform on the processing surface, the shape of the processing surface changes from the original spherical shape in the process of using the polishing tool, which affects the processing accuracy of the optical element. I will give it.

  In order to make the amount of wear on the machined surface uniform, Patent Document 1 discloses a technology that distributes the ease of wear of the grindstone itself by changing the bubble content on the inner and outer circumferential sides of the grindstone. Proposed. Specifically, the pore-containing structure in the grindstone is made smaller on the outer peripheral side than on the inner peripheral side. As a result, the outer peripheral side is less likely to be worn than the inner peripheral side, so that when the processing surface is brought into contact with the optical element and rotated, the wear of the grindstone can be made uniform.

JP-A-61-103768

  However, Patent Document 1 does not disclose a specific method for changing the content of pores in the grindstone in the radial direction. As a method of incorporating pores in the grindstone, for example, a method of mixing a foaming agent into the raw material powder (abrasive grains) before molding can be considered. By such a method, the pore content is changed in the radial direction. Is very difficult and complicates the manufacturing process.

  The present invention has been made in view of the above, and requires a complicated process for a polishing tool in which the polishing rate on the outer peripheral side is increased with respect to the inner peripheral side by changing the bubble content in the radial direction. An object of the present invention is to provide a polishing tool manufacturing method, a polishing tool, and a mold for manufacturing a polishing tool that can be manufactured without any problems.

  In order to solve the above-described problems and achieve the object, a manufacturing method of a polishing tool according to the present invention includes a cylindrical mold having openings at both ends and a mold capable of reducing diameter and the openings at both ends. A powder injection step of introducing a powder containing an abrasive into a mold comprising two molds to be stopped, and compressing the powder by reducing the diameter of the mold by applying a radial force to the mold And a powder compression step.

  In the method for manufacturing an abrasive tool, each of the molds has a pressing surface that presses the powder, and a plurality of columnar members arranged with the pressing surface facing an inner peripheral side, and the plurality of columnar members A plurality of intermediate members disposed between adjacent columnar members and sealing gaps between the adjacent columnar members, wherein the powder compaction step includes the plurality of columnar members of the mold. The diameter of the mold is reduced by moving in a central axis direction.

  In the polishing tool manufacturing method, the mold includes three or more columnar members.

  In the method for manufacturing the polishing tool, the mold is formed of an elastic body that has a cylindrical shape and can be expanded and contracted, and the powder compression step pressurizes the mold in a radial direction so that an inner periphery and an outer periphery of the mold are formed. It is made to shrink.

  The polishing tool according to the present invention comprises a powder containing an abrasive in a forming die comprising a cylindrical mold having openings at both ends and a mold capable of sealing the openings at both ends. It was produced by putting a body, compressing the powder by applying a radial force to the mold to reduce the diameter of the mold.

  The mold for manufacturing an abrasive tool according to the present invention has a cylindrical shape with openings formed at both ends, and an upper mold and a lower mold that are filled with powder containing abrasives and seal the upper and lower openings, respectively. A cylindrical portion that compresses the powder by reducing the diameter while being sandwiched between the molds is provided.

  According to the present invention, the powder is put into a cylindrical mold that can be reduced in diameter, and the powder is compressed by reducing the diameter of the mold. Therefore, the compression density of the powder, that is, the bubble content rate is reduced. It can be varied in the radial direction. Therefore, it is possible to manufacture a polishing tool having a higher polishing ability on the outer peripheral side than on the inner peripheral side without requiring a complicated process.

FIG. 1A is a longitudinal sectional view showing a mold for manufacturing a polishing tool used in the method for manufacturing a polishing tool according to Embodiment 1 of the present invention. FIG. 1B is a cross-sectional view of the mold for manufacturing the polishing tool shown in FIG. 1A when viewed on a cut surface orthogonal to the paper surface including the AA line. FIG. 2A is a longitudinal sectional view showing a state where the diameter of the mold for manufacturing the polishing tool shown in FIG. 1A is reduced. 2B is a cross-sectional view showing a state where the diameter of the mold for manufacturing the polishing tool shown in FIG. 1B is reduced. FIG. 3 is a flowchart showing a method for manufacturing a polishing tool according to Embodiment 1 of the present invention. FIG. 4 is a graph showing the density distribution of the polishing tool according to Embodiment 1 of the present invention. FIG. 5A is a longitudinal sectional view for explaining a general method of manufacturing a polishing tool. FIG. 5B is a longitudinal sectional view for explaining a general method of manufacturing a polishing tool. FIG. 6 is a graph showing a density distribution in a conventional polishing tool. FIG. 7A is a cross-sectional view showing a horizontal punch used in the method for manufacturing a polishing tool according to Embodiment 2 of the present invention. FIG. 7B is a transverse cross-sectional view showing a state where the diameter of the transverse punch shown in FIG. 7A is reduced. FIG. 8A is a cross-sectional view showing a horizontal punch used in the method for manufacturing a polishing tool according to Embodiment 3 of the present invention. FIG. 8B is a cross-sectional view showing a state in which the diameter of the horizontal punch shown in FIG. 8A is reduced. FIG. 9A is a cross-sectional view showing a horizontal punch used in the method for manufacturing a polishing tool according to Embodiment 4 of the present invention. FIG. 9B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 9A is reduced. FIG. 10A is a cross-sectional view showing a horizontal punch used in the method for manufacturing a polishing tool according to Embodiment 5 of the present invention. FIG. 10B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 10A is reduced. FIG. 11A is a cross-sectional view showing a horizontal punch used in the method for manufacturing a polishing tool according to Embodiment 6 of the present invention. FIG. 11B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 11A is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by these embodiments. Moreover, in description of each drawing, the same code | symbol is attached | subjected and shown to the same part. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each part are different from the actual ones. Also between the drawings, there are included portions having different dimensional relationships and ratios.

(Embodiment 1)
1A to 2B are diagrams showing a polishing tool manufacturing die used in the method for manufacturing a polishing tool according to Embodiment 1 of the present invention. 1A is a longitudinal sectional view showing the mold for manufacturing the polishing tool, and FIG. 1B is a cross-sectional view of the mold for manufacturing the polishing tool shown in FIG. 1A perpendicular to the paper surface including the line AA. FIG. 2A and 2B are cross-sectional views showing states in which the diameter of the polishing tool manufacturing mold shown in FIGS. 1A and 1B is reduced.

  A mold 10 shown in FIGS. 1A and 1B includes a lower die 11 and an upper die 12, and a horizontal punch 13 sandwiched therebetween. The horizontal punch 13 has a cylindrical shape with openings 17 and 18 formed at both ends, and has a structure capable of reducing the diameter. The lower die 11 and the upper die 12 are flat plates formed of a hard material such as a metal or an alloy, and seal the lower end opening 17 and the upper end opening 18 of the lateral punch 13, respectively.

  As shown in FIG. 2B, the horizontal punch 13 includes four columnar members 13a to 13d and adjacent columnar members (columnar members 13a and 13b, columnar members 13b and 13c, columnar members 13c and 13d, columnar members 13d and 13a). Intermediate members 14a to 14d respectively disposed between them.

  Each of the columnar members 13a to 13d has a curved surface 15 having a shape obtained by dividing the same cylindrical surface in the radial direction, and two side surfaces 16 provided at both ends of the curved surface 15, respectively. Is arranged along the circumference having a predetermined diameter. In FIG. 2B, columnar members 13a to 13d are formed by dividing one cylindrical member into four. In addition, the number which divides | segments a cylindrical member is not specifically limited, Preferably it is good to divide | segment into three or more. Moreover, the shape of the outer peripheral side of the cylindrical member is not particularly limited. Such columnar members 13a to 13d are formed of a hard material such as a metal or an alloy.

  Each of the intermediate members 14a to 14d is formed of a stretchable elastic body such as polyurethane, polystyrene, butyl rubber, or silicone rubber, and has a column shape having the same height as the columnar members 13a to 13d. Each of the intermediate members 14a to 14d is fixed to the side surface 16 of the adjacent columnar members 13a to 13d with an adhesive or the like, and seals the gap between the adjacent columnar members 13a to 13d.

  When the diameter of the lateral punch 13 is reduced, as shown in FIGS. 2A and 2B, a load in the direction of the central axis C is applied to each of the columnar members 13a to 13d. Thereby, while each columnar member 13a-13d moves to the direction of the central axis C, intermediate member 14a-14d contracts, the curved surfaces 15 of columnar member 13a-13d approach, and the internal peripheral surface of the horizontal punch 13 Approaches a cylindrical surface.

Next, a method for manufacturing a polishing tool according to Embodiment 1 of the present invention will be described. FIG. 3 is a flowchart showing the method for manufacturing the polishing tool according to the first embodiment.
In step S1, a powder containing an abrasive (abrasive grains) that is a raw material of the polishing tool is produced. In Embodiment 1, a composite powder in which an abrasive is bound with a resin is used as a raw material. For this purpose, first, a resin solution is prepared by dissolving a powder or flaky resin material in a solvent. As the resin material, phenol resin, epoxy resin, polyimide resin, polyamide resin, etc. are used. If necessary, silane, titanium coupling agent, fluorocarbon, molybdenum disulfide, ethylene fluoride, A reinforced resin or the like is added. As the solvent, organic solvents such as NMP, monoglyme, diglyme, butyl lactone, toluene, acetone, and trichrene are used.

  Subsequently, an abrasive mud (slurry) is prepared by mixing and stirring the powdery abrasive in the resin solution. As the abrasive, cerium oxide, zirconium oxide, aluminum oxide, chromium oxide, diamond and the like are used. Then, the abrasive mud is stretched thinly, the solvent is volatilized and dried to produce a sheet-like composite material. Furthermore, this sheet-like composite material is pulverized into flakes, and pulverized using a mixer, a ball mill, a mortar or the like until it becomes powdery. This is the raw material powder. The particle size of the powder is not particularly limited and is preferably in the range of about 1 μm to about 500 μm.

In the subsequent step S2, the horizontal punch 13 is set on the lower die 11 (see FIG. 1A).
In the subsequent step S3, a necessary amount of the raw material powder 1 produced in the step S1 is weighed and put into the inside of the mold composed of the lower die 11 and the horizontal punch 13. In addition, since the gaps between the columnar members 13 a to 13 d are sealed by the intermediate members 14 a to 14 d, the powder 1 does not leak from the side surface 16 of the lateral punch 13.

  In the subsequent step S4, the upper die 12 is set on the horizontal punch 13. Thereby, the opening 18 at the upper end of the horizontal punch 13 is sealed. Further, the lower die 11 and the upper die 12 may be fixed using a jig or the like.

  In the subsequent step S5, a molding die composed of the lower die 11, the lateral punch 13 and the upper die 12 is set in a compression molding machine, and a radial force is applied to the lateral punch 13 to reduce the diameter to thereby reduce the internal powder. 1 is compressed (see FIGS. 2A and 2B). Specifically, the columnar members 13a to 13d constituting the horizontal punch 13 are pushed in the direction of the central axis C, the columnar members 13a to 13d are moved in the direction of the central axis C, and the intermediate members 14a to 14d are contracted, The diameter of the horizontal punch 13 is reduced. Thereby, each curved surface 15 becomes a pressing surface and compresses the powder 1, and a substantially cylindrical green compact is formed. The load applied to the lateral punch 13 is determined so that a predetermined molding pressure is applied to the internal powder 1.

  In the subsequent step S6, the molding die including the lower die 11, the horizontal punch 13, and the upper die 12 is removed from the compression molding machine, and the green compact is taken out from the horizontal punch 13 and heated. Thereby, the resins contained in the powder 1 are welded together, and a substantially cylindrical grindstone member is obtained. The processing conditions such as the heating temperature and the heating time are appropriately set according to the type of resin.

  In the subsequent step S7, a spherical surface is formed on the substantially cylindrical grindstone member by curve generator processing or the like, and further lapping is performed to form a processing surface having a spherical shape with a desired curvature. Thereby, the polishing tool according to Embodiment 1 is completed.

  The polishing tool manufactured in this way has the following characteristics. FIG. 4 is a graph showing the distribution of compression density in the green compact produced in step S5. As described above, since the powder 1 is compressed by reducing the diameter of the horizontal punch 13 in the first embodiment, the amount of movement during compression is larger in the powder 1 located on the outer peripheral side in the horizontal punch 13. Become. For this reason, as shown in FIG. 4, the compression density in the area | region R of the outer peripheral side rather than the central axis C of a green compact becomes high. Therefore, in the grindstone member obtained by heating such a green compact, the bubble content is the highest in the vicinity of the central axis C and gradually decreases from the central axis C toward the outer peripheral region R. That is, the grindstone member is less likely to be worn on the outer peripheral side than on the inner peripheral side.

  As described above, according to the first embodiment, a polishing tool in which the bubble content rate is changed in the radial direction and the polishing ability on the outer peripheral side is increased with respect to the inner peripheral side is manufactured in a simple process. Is possible.

The first embodiment also has the following advantages. In general, as shown in FIGS. 5A and 5B, a cylindrical polishing tool is formed by putting raw material powder 94 into a mold in which a lower punch 92 is set on the inner periphery of a cylindrical die 91, The upper punch 93 is set on the inner periphery of 91, and a load is applied to the upper punch 93 to compress the powder 94. However, according to this method, since the powder 94 closer to the upper punch 93 has a longer moving distance during compression, the compression density in the vicinity of the upper punch 93 (for example, the height h ₂ ) is higher as shown in FIG. The compression density decreases as the distance from the upper punch 93 increases (for example, the height h ₁ ). That is, the compression density becomes non-uniform in the height direction of the green compact.

  As another method for forming a grindstone, a method of compressing the powder 94 by applying a load to both the lower punch 92 and the upper punch 93 is also known. However, in this case, the compression density in the vicinity of the lower punch 92 and the upper punch 93 is high, the compression density in the center is low, and the compression density is also uneven in the height direction of the green compact. And if the compression density becomes uneven in the height direction of the green compact in this way, even in the polishing tool produced by heating the green compact, the air content becomes uneven in the height direction, This is not preferable because the polishing ability changes in the process of using the polishing tool and stable polishing cannot be performed.

  However, according to the first embodiment, since the powder charged in the mold is compressed in the radial direction, the compression density can be made uniform in the height direction of the green compact as shown in FIG. . Therefore, in a polishing tool manufactured from such a green compact, the polishing ability does not change even during the use process, and stable polishing can be performed.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
The manufacturing method of the polishing tool according to the second embodiment of the present invention is generally the same as that of the first embodiment, and the structure of the polishing tool manufacturing die (lateral punch) used for compressing the powder 1 is the embodiment. Different from 1.

  FIG. 7A is a cross-sectional view showing a horizontal punch used in Embodiment 2, and shows a state in which powder 1 is charged into the horizontal punch. FIG. 7B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 7A is reduced. 7A and 7B, the description of the lower die 11 (see FIG. 1A) is omitted.

  As shown in FIG. 7A, the horizontal punch 20 used in the second embodiment includes a plurality of columnar members 21a to 21d and adjacent columnar members (columnar members 21a and 21b, columnar members 21b and 21c, columnar members 21c and 21d. And a plurality of intermediate members 22a to 22d disposed between the columnar members 21d and 21a).

  Each of the columnar members 21a to 21d has a curved surface 23 having a shape obtained by dividing the same cylindrical surface in the radial direction, as in the first embodiment, and the curved surface 23 faces the inner peripheral side and has a predetermined diameter. It is arrange | positioned along the circumference which has. In the second embodiment, since the columnar members 21a to 21d are formed by dividing the cylindrical member into four, the outer peripheral surfaces of the columnar members 21a to 21d are column surfaces concentric with the curved surface 23. The shape is divided in the radial direction.

  Each of the intermediate members 22a to 22d is formed of a stretchable elastic body such as polyurethane, polystyrene, butyl rubber, or silicone rubber, as in the first embodiment, and has a column shape having the same height as the columnar members 21a to 21d. . Each of the intermediate members 22a to 22d is bonded to the side surface 24 of the adjacent columnar members 21a to 21d, and seals the gap between the adjacent columnar members 21a to 21d.

  In the second embodiment, each of the intermediate members 22a to 22d is provided so as to protrude to the inner peripheral side from the curved surface 23 of the adjacent columnar members 21a to 21d. Here, as shown in FIG. 3B, when the diameter of the horizontal punch 13 is reduced, if the powder 1 enters the gap between the adjacent columnar members 13 a to 13 d, the intermediate members 14 a to 14 d sufficiently entrain the powder 1. May not be able to shrink. In this case, the displacement of the columnar members 13a to 13d toward the inner peripheral side is hindered, so that sufficient pressure cannot be applied to the powder 1 and a desired compression density cannot be obtained.

  Therefore, in the second embodiment, the intermediate members 22a to 22d are protruded inward from the curved surface 23 of the columnar members 21a to 21d, so that the powder 1 enters the gaps between the columnar members 21a to 21d. Is preventing. Thus, as shown in FIG. 7B, even when the diameter of the horizontal punch 20 is reduced, the intermediate members 22a to 22d between the columnar members 21a to 21d are sufficiently contracted to obtain a desired compression density for the powder 1. Can be obtained.

  In addition, the shape of the protruding portion 25 of the intermediate members 22a to 22d may be a bell shape as shown in FIG. 7A, or may be another shape as long as the penetration of the powder 1 can be prevented.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
The manufacturing method of the polishing tool according to the third embodiment of the present invention is generally the same as that of the first embodiment, and the structure of the polishing tool manufacturing die (lateral punch) used for compressing the powder 1 is the embodiment. Different from 1.

  FIG. 8A is a cross-sectional view showing a horizontal punch used in Embodiment 3, and shows a state in which powder 1 is charged into the horizontal punch. 8B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 8A is reduced. 8A and 8B, the description of the lower die 11 (see FIG. 1A) is omitted.

  As shown in FIG. 8A, the horizontal punch 30 used in Embodiment 3 includes a plurality of columnar members 31a to 31d and support members 32a to 32d that support the columnar members 31a to 31d. Each of the columnar members 31 a to 31 d has a curved surface 33 having a shape obtained by dividing the same cylindrical surface in the radial direction, and two side surfaces 34 provided at both ends of the curved surface 33, respectively. Is arranged along the circumference having a predetermined diameter. Such columnar members 31a to 31d are formed of a hard material such as a metal or an alloy.

  The support members 32a to 32d have a plurality of contact surfaces 35 that are in contact with the side surfaces 34 of the columnar members 31a to 31d, respectively, and have a columnar shape that is the same height as the columnar members 31a to 31d. These support members 32a to 32d support the columnar members 31a to 31d so as to be slidable along the contact surfaces 35 in contact with the columnar members 31a to 31d. For example, the columnar member 31a has the side surface 34 in contact with the contact surface 35 of the support members 32a and 32b, and is movable along the contact surface 35 in the left-right direction in the figure.

  Further, the contact surfaces 35 of the support members 32a to 32d seal the side surfaces 34 of the columnar members 31a to 31d, and prevent leakage of the powder 1 disposed on the inner peripheral side of the columnar members 31a to 31d. These support members 32a to 32d may be provided integrally via a connecting member (not shown) or may be provided individually. In the latter case, the support members 32a to 32d may be directly fixed on the lower die 11 (see FIG. 1A). Such support members 32a to 32d are formed of a hard material such as a metal or an alloy, like the columnar members 31a to 31d.

  When the diameter of the horizontal punch 30 is reduced, the columnar members 31 a to 31 d are pressed in the direction of the central axis C and are slid along the contact surface 35 as shown in FIG. 8B. Thereby, the powder 1 thrown in the horizontal punch 30 is compressed, and a green compact is produced.

  According to the third embodiment described above, leakage of the powder 1 can be prevented without interposing an intermediate member between the adjacent columnar members 31a to 31d. Therefore, when the diameter of the horizontal punch 30 is reduced, the adjacent curved surfaces 33 of the columnar members 31a to 31d can be connected to each other so that the inner peripheral surface of the horizontal punch 30 can be made into a complete cylindrical surface.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.
The manufacturing method of the polishing tool according to the fourth embodiment of the present invention is generally the same as that of the first embodiment, and the structure of the polishing tool manufacturing die (lateral punch) used for compressing the powder 1 is the embodiment. Different from 1.

  FIG. 9A is a cross-sectional view showing a horizontal punch used in Embodiment 4, and shows a state where powder 1 is charged into the horizontal punch. FIG. 9B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 9A is reduced. 9A and 9B, the description of the lower die 11 (see FIG. 1A) is omitted.

  As shown in FIG. 9A, the horizontal punch 40 used in the fourth embodiment includes a plurality of columnar members 41a to 41d and adjacent columnar members (columnar members 41a and 41b, columnar members 41b and 41c, columnar members 41c and 41d. And a plurality of intermediate members 42a to 42d disposed between the columnar members 41d and 41a). Each of the columnar members 41a to 41d has a curved surface 43 having a shape obtained by dividing the same cylindrical surface in the radial direction, and the curved surface 43 is directed toward the inner peripheral side, and is arranged along a circumference having a predetermined diameter. Has been. Each columnar member 41a to 41d is provided with a hole 44 for fitting a part of the adjacent intermediate members 42a to 42d. Such columnar members 41a to 41d are formed of a hard material such as a metal or an alloy.

  Each of the intermediate members 42a to 42d has a sealing surface 45 that is convex toward the inner peripheral side of the columnar members 41a to 41d, and insertion portions 46 that are provided at both ends of the sealing surface 45. The columnar members 41a to 41d are columnar with the same height. The shape of the sealing surface 45 is such that the side end portions of the adjacent curved surfaces 43 are in close contact with the sealing surface 45 when the insertion portion 46 is inserted into the holes 44 of the adjacent columnar members 41 a to 41 d. Yes. The intermediate members 42a to 42d are formed of a hard material such as a metal or an alloy, like the columnar members 41a to 41d.

  When reducing the diameter of the horizontal punch 40, the columnar members 41a to 41d are pressed and moved in the direction of the central axis C as shown in FIG. 9B. Accordingly, the insertion portions 46 of the intermediate members 42a to 42d are adjacent to the columnar members 41a to 41d while maintaining the positions of the intermediate members 42a to 42d and the side end portions of the curved surface 43 and the sealing surface 45 in contact with each other. It is inserted further into the hole 44 of 41d. That is, only the relative positional relationship between the columnar members 41a to 41d and the intermediate members 42a to 42d changes.

  At this time, the curved surfaces 43 of the adjacent columnar members 41 a to 41 d approach each other while changing the contact position with the sealing surface 45 while reducing the diameter and pressing the powder 1, and finally the curved surfaces 43. Side ends are connected. Thereby, the internal peripheral surface of the horizontal punch 40 becomes a cylindrical surface shape.

  According to the fourth embodiment described above, the adjacent curved surfaces 43 of the columnar members 41a to 41d are brought into close contact with each other while preventing the leakage of the powder 1 by the intermediate members 42a to 42d, and the inner periphery of the horizontal punch 40 The surface can be a complete cylindrical surface.

  In the fourth embodiment, the gaps between the columnar members 41 a to 41 d are sealed by pressing the intermediate members 42 a to 42 d from the outer peripheral side of the curved surface 43, but on the inner peripheral side of the curved surface 43, You may provide the intermediate member which seals the gap | interval of adjacent columnar member 41a-41d. In this case, the leakage of the powder 1 can be prevented by bringing the side end surface of the intermediate member into contact with the adjacent curved surfaces 43.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described.
The manufacturing method of the polishing tool according to the fifth embodiment of the present invention is generally the same as that of the first embodiment, and the structure of the polishing tool manufacturing die (lateral punch) used for compressing the powder 1 is the embodiment. Different from 1.

  FIG. 10A is a cross-sectional view showing a horizontal punch used in Embodiment 5, and shows a state in which powder 1 is charged into the horizontal punch. FIG. 10B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 10A is reduced. In FIGS. 10A and 10B, the description of the lower die 11 (see FIG. 1A) is omitted.

  As shown in FIG. 10A, the horizontal punch 50 used in Embodiment 5 includes a plurality of columnar members 51 and a plurality of intermediate members 52 that are respectively disposed between adjacent columnar members 51. As in the first embodiment, each columnar member 51 has a shape obtained by dividing a cylindrical member having an inner peripheral surface in a cylindrical surface shape in the radial direction of the cylindrical surface, and a curved surface 53 is directed toward the inner peripheral side. It arrange | positions along the periphery which has a diameter. In the fifth embodiment, the columnar member 51 is formed by dividing the cylindrical member into eight.

  Each intermediate member 52 is formed of an elastic body that can be expanded and contracted as in the first embodiment, and has a columnar shape that is the same height as the columnar members 13a to 13d. Each intermediate member 52 is bonded to the side surface of the adjacent columnar member and seals the gap between the adjacent columnar members 51.

  When the diameter of the horizontal punch 50 is reduced, as shown in FIG. 10B, each columnar member 51 is pressed in the direction of the central axis C, the columnar member 51 is moved in the direction of the central axis C, and the intermediate member 52 is contracted. Let Thereby, the powder 1 put in the horizontal punch 50 is compressed, and a green compact is produced.

  Here, the number of the columnar members 51 constituting the horizontal punch 50 is not particularly limited as long as it is preferably 3 or more, but the larger the number of the columnar members 51, the more preferable. This is because, as the number of columnar members 51 increases, the number of powders 1 that are moved in the direction of the central axis C by the columnar members 51 increases, so that the compression density distribution of the powders 1 in the radial direction becomes more uniform. .

Actually, the number of columnar members 51 constituting the horizontal punch 50 may be increased within a possible range according to the configuration of the compression molding machine that applies a load to the horizontal punch 50.
Similarly, in Embodiments 2 to 4, it is preferable to increase the number of columnar members constituting the horizontal punches 20 to 40 as much as possible.

  In the fifth embodiment, the inner peripheral surface of each columnar member 51 is a curved surface. However, when the number of columnar members 51 is large (for example, six or more), the inner peripheral surface is flat. It is also good. In this case, a polygonal column-shaped grindstone member is obtained. The polygonal column-shaped grindstone member may be used as a polishing tool simply by processing the end face as it is, or after grinding the outer peripheral surface of the polygonal column into a cylindrical shape, the end surface is processed and used as a polishing tool You may do it. Even in the case of processing into a cylindrical shape, if the polygonal column is a hexagonal column or more (6 or more columnar members 51), the portion removed by grinding of the outer peripheral surface is 10% or less of the whole, which is wasteful. Less is.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described.
The manufacturing method of the polishing tool according to the sixth embodiment of the present invention is generally the same as that of the first embodiment, and the structure of the polishing tool manufacturing die (lateral punch) used for compressing the powder 1 is the embodiment. Different from 1.

  FIG. 11A is a cross-sectional view showing a horizontal punch used in Embodiment 6, and shows a state where powder 1 is charged into the horizontal punch. FIG. 11B is a cross-sectional view showing a state where the diameter of the horizontal punch shown in FIG. 11A is reduced. In FIG. 11A and FIG. 11B, the description of the lower die 11 (see FIG. 1A) is omitted.

  As shown in FIG. 11A, the horizontal punch 60 used in Embodiment 6 has a cylindrical shape with openings formed at both ends, and is formed of a stretchable elastic body such as polyurethane, polystyrene, butyl rubber, or silicone rubber. Yes. When the diameter of the horizontal punch 60 is reduced, a uniform pressure is applied around the horizontal punch 60 as shown in FIG. 11B. As the pressurizing mechanism, either water pressure or hydraulic pressure may be used.

Next, a method for manufacturing a polishing tool according to Embodiment 6 will be described with reference to FIG. Steps S1 to S3 are the same as those in the first embodiment.
In step S4 following step S3, the inside of the horizontal punch 60 into which the powder 1 has been charged is evacuated to be in a vacuum state, and then the upper die 12 (see FIG. 1A) is set on the horizontal punch 60, a jig or the like. The lower die 11 and the upper die 12 are fixed using Here, the reason why the inside of the horizontal punch 60 is evacuated is that the diameter of the horizontal punch 60 is reduced by hydraulic pressure or hydraulic pressure in the sixth embodiment, so that there is no escape space for air. This is because the diameter is hindered.

In the subsequent step S5, with the vacuum state in the horizontal punch 60 maintained, a molding die composed of the lower die 11, the horizontal punch 60, and the upper die 12 is set in a pressure vessel, and the molding die is pressurized. Thereby, a uniform pressure is applied in the radial direction of the horizontal punch 60 to reduce the diameter of the horizontal punch 60, and the inner peripheral surface of the horizontal punch 60 serves as a pressing surface to compress the powder 1.
The subsequent step S6 and subsequent steps are the same as in the first embodiment.

  According to the sixth embodiment described above, all the powder 1 at the peripheral edge moves toward the central axis C due to the reduced diameter of the horizontal punch 60, so that the compression density distribution of the powder 1 in the radial direction is made uniform. be able to.

  In the sixth embodiment, the powder 1 is put into the horizontal punch 60 and then evacuated. However, the powder 1 is put into the horizontal punch 60 and the lower die 11 and the upper die 12 are fixed. The above steps may be performed in a vacuum atmosphere.

DESCRIPTION OF SYMBOLS 1,94 Powder 10 Mold 11 Lower die 12 Upper die 13, 20, 30, 40, 50, 60 Horizontal punch 13a-13d, 21a-21d, 31a-31d, 41a-41d, 51 Columnar member 14a-14d, 22a-22d, 42a-42d, 52 Intermediate member 15, 23, 33, 43, 53 Curved surface 16, 24, 34 Side surface 17, 18 Opening 25 Protruding portion 32a-32d Support member 35 Contact surface 44 Hole 45 Sealing surface 46 Insertion part 91 Die 92 Lower punch 93 Upper punch

Claims (3)

Powder feeding step of feeding powder containing abrasives into a mold comprising a cylindrical mold having openings at both ends and capable of reducing diameter and two molds that seal the openings at both ends, respectively. When,
A powder compression step of compressing the powder by applying a radial force to the mold to reduce the diameter of the mold;
Only including,
The mold is
Each having a pressing surface for pressing the powder, and a plurality of columnar members arranged with the pressing surface facing the inner periphery;
Among the plurality of columnar members, a plurality of intermediate members that are arranged between adjacent columnar members and seal a gap between the adjacent columnar members;
With
In the powder compression step, the diameter of the mold is reduced by moving the plurality of columnar members in the direction of the central axis of the mold . The method for manufacturing a polishing tool according to claim 1 , wherein the mold includes three or more columnar members. By forming a cylindrical shape with openings at both ends, powder containing abrasives is put inside, and reducing the diameter while sandwiched between the upper mold and the lower mold that seal the upper and lower openings, respectively. A cylindrical portion for compressing the powder ;
The cylindrical part is
Each having a pressing surface for pressing the powder, and a plurality of columnar members arranged with the pressing surface facing the inner periphery;
Among the plurality of columnar members, a plurality of intermediate members that are arranged between adjacent columnar members and seal a gap between the adjacent columnar members;
The provided type of polishing tool manufacture, characterized in Rukoto.

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