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CN-117858857-B - Raw material for ceramic ball, ceramic ball and method for producing same

CN117858857BCN 117858857 BCN117858857 BCN 117858857BCN-117858857-B

Abstract

The ceramic ball material according to the embodiment has a spherical surface portion and a band portion formed in a band shape. The ceramic ball material is characterized in that, when the roundness when viewed from the height direction of the band-shaped portion is C, the roundness C is in the range of more than 0% and 2.5% or less. The material for ceramic balls can improve the durability of the grinding stone during grinding. The ceramic may be any one or more of aluminum oxide, silicon nitride, boron nitride, and zirconium oxide.

Inventors

  • Funaki Yutaka
  • YAMADA YASUHIKO
  • SANO Shoya

Assignees

  • 株式会社东芝
  • 东芝高新材料公司

Dates

Publication Date
20260512
Application Date
20220929
Priority Date
20210929

Claims (9)

  1. 1. A ceramic ball material having a spherical portion and a band portion formed in a band shape, characterized in that, When the roundness when viewed from the height direction of the belt-like portion is C, The roundness C is in a range of more than 0% and 0.5% or less, The roundness C is obtained by the following method: Dividing the ceramic ball raw material into 12 parts or more at equal intervals by 12 or more diameters as seen in the height direction of the band-shaped portion, dividing each diameter by 2 to obtain a radius, setting the average value of the radii to be the average diameter rA, setting the maximum value of the radii to be r max , setting the minimum value of the radii to be r min , obtaining the roundness C of the ceramic ball raw material by the following formula (1), Roundness C (%) = (r max -r min )/ra×100..1.
  2. 2. The raw material for ceramic balls according to claim 1, wherein, When the roundness of the spherical surface portion when viewed from the height direction of the strip portion is C ', the roundness C' is in a range of more than 0% and 1.5% or less, The roundness C' is obtained by the following method: The spherical surface portion of the ceramic ball raw material as seen from the height direction of the band portion is divided into 12 parts or more at equal intervals by 12 or more diameters, a value obtained by dividing each diameter by 2 is defined as a radius, an average value of the radii is defined as an average diameter rA ', a maximum value of the radii is defined as r' max , a minimum value of the radii is defined as r ' min , and the roundness C' is obtained by the following formula (2), Roundness C ' (%) = (r ' max -r' min )/rA ' ×100..2.
  3. 3. The raw material for ceramic balls according to claim 1 or 2, wherein, The roundness C' of the spherical surface portion when viewed from the height direction of the strip portion is in a range of more than 0% and 1.3% or less.
  4. 4. The raw material for ceramic balls according to claim 1 or 2, wherein, When the roundness when viewed from the direction orthogonal to the height direction of the strip portion is C ", The roundness C' is in the range of 0% to 1.5%, The roundness C' is obtained by the following method: The ceramic ball raw material as seen from the direction perpendicular to the height direction of the band portion is divided into 12 parts or more at equal intervals by 12 or more diameters, a value obtained by dividing each diameter by 2 is defined as a radius, an average value of the radii is defined as an average diameter rA ', a maximum value of the radii is defined as r' max , a minimum value of the radii is defined as r ' min , and the roundness C' is obtained by the following formula (3), Roundness C "(%) = (r" max -r" min )/rA "×100..3.
  5. 5. The raw material for ceramic balls according to claim 1 or 2, wherein, The raw material for ceramic balls contains at least 85 mass% of one or more of alumina, silicon nitride, boron nitride, zirconia, silicon carbide and sialon.
  6. 6. The raw material for ceramic balls according to claim 1 or 2, wherein, The raw material for ceramic balls is a sintered body containing 85 mass% or more of silicon nitride.
  7. 7. A method for producing ceramic balls, characterized by polishing the ceramic ball raw material according to any one of claims 1 to 6.
  8. 8. A ceramic ball obtained by polishing the raw material for ceramic balls according to any one of claims 1 to 6.
  9. 9. A bearing is characterized in that, Use of the ceramic balls of claim 8.

Description

Raw material for ceramic ball, ceramic ball and method for producing same Technical Field The embodiments described below relate to a ceramic ball material, a ceramic ball, and a method for producing the same. Background Various ceramic materials have characteristics such as high hardness, insulation, and abrasion resistance, and particularly fine ceramics having improved purity and uniform particle size are useful in various fields such as capacitors, actuator materials, and refractory materials. Among them, as products exhibiting wear resistance and insulation properties, there are bearing ball applications, and materials such as alumina, silicon nitride, zirconia, silicon carbide, sialon (Sialon) and the like are used. For example, japanese patent application laid-open nos. 6-48813 (patent document 1) and 2764589 (patent document 2) disclose bearing balls using a silicon nitride material, and japanese patent application laid-open No. 60-18620 (patent document 3) disclose bearing balls using a zirconia material. In addition, the ceramic balls described above may be subjected to polishing suitable for various applications such as bearing applications, using a platen process or the like described in japanese patent No. 5334040 (patent document 5). In the process for producing these materials for bearing balls, a method of sintering a molded body is used. In addition, the molding method uses press molding using a die. As shown in fig. 1, press molding is generally a method of inserting powder between an upper die 1 and a lower die 2 and applying pressure. In the press molding, in order to protect the dies, it is necessary to provide a gap between the front end portion 3 of the upper die 1 and the front end portion 4 of the lower die 2 and perform press molding. Therefore, the spherical surface portion and the belt-shaped portion are formed on the molded body produced by press molding. For example, japanese patent No. 4761613 (patent document 4) discloses a material for bearing balls having a ball surface portion and a belt portion. Fig. 2 shows a ceramic ball material described in patent document 4. In fig. 2, 7 is a ceramic ball material, 6 is a spherical surface portion, and 5 is a belt portion. Prior art literature Patent literature Patent document 1 Japanese patent laid-open No. 6-48813 Patent document 2 Japanese patent No. 2764589 Patent document 3 Japanese patent laid-open No. 60-18620 Patent document 4 Japanese patent No. 4761613 Patent document 5 Japanese patent No. 5334040 Disclosure of Invention Problems to be solved by the invention The ceramic ball is formed by polishing a ceramic ball raw material having a spherical surface portion 6 and a belt portion 5. The ceramic ball subjected to the polishing process is particularly suitable for use as a bearing ball. The ceramic ball raw material 7 having the spherical surface portion 6 and the belt portion 5 is also sometimes referred to as a raw material ball. For example, the bearing ball is mirror finished to have a surface roughness Ra of 0.1 μm or less. Mirror finish is performed using a stage. Ceramic materials are excellent in wear resistance, but are brittle materials and have high hardness, and therefore require more steps than metals. In particular, since the initial step of increasing the positive sphericity to a desired value has a large processing margin, the processing time is a large fraction of the total steps. Since the processing time is longer as the sphericity (roundness) before processing is larger, the sphericity of the raw material for ceramic balls before processing needs to be set to a value as small as possible. The present invention has been made to solve the above problems, and an object of the present invention is to provide a ceramic ball raw material having a high sphericity, which can shorten the processing time of a ceramic material processed by a platen, in particular, during polishing. Means for solving the problems The ceramic ball material according to the embodiment has a spherical surface portion and a band portion formed in a band shape. The method is characterized in that, when the roundness when viewed from the height direction of the strip-shaped part is C, the roundness C is in the range of more than 0% and less than 2.5%. Drawings Fig. 1 is a diagram showing an example of the press molding of a mold. Fig. 2 is a diagram showing an example of a conventional ceramic ball raw material. Fig. 3 is a diagram schematically showing a measurement direction (first measurement direction) in the ceramic ball raw material according to the embodiment. Fig. 4 is a view schematically showing an image obtained by observing the ceramic ball raw material according to the embodiment from the first measurement direction. Fig. 5 is a diagram schematically showing a measurement direction (second measurement direction) in the ceramic ball raw material according to the embodiment. Fig. 6 is a view schematically showing an image obtain