Spherical body polishing apparatus, method for polishing spherical body and method for manufacturing spherical member

A method for polishing a spherical body, comprising the steps of:

• arranging a spherical body to be processed between a first member having a first polishing surface and a second member having a second polishing surface opposed to said first polishing surface;
• and
• polishing said spherical body by applying a relative rotation to said first polishing surface and said second polishing surface while keeping said first and second polishing surfaces opposed to each other,
• at least one of said first polishing surface and said second polishing surface having a groove portion formed therein and extending circumferentially along said rotation,
• at least one of said first member and said second member having said groove portion formed therein including:
• an abrasive grain layer including an abrasive grain having a higher hardness than that of said spherical body, wherein said abrasive grain layer has a configuration in which said abrasive grains are bonded together with a bonding agent, and
• a holding layer formed on said abrasive grain layer and having a lower hardness than that of said abrasive grain layer, wherein said holding layer has, in a cross section perpendicular to a direction in which said groove portion extends, an arc-shaped wall surface, and said holding layer is formed of said bonding agent,
• said groove portion being formed to penetrate said holding layer in a depth direction and to reach said abrasive grain layer,
• said groove portion has a bottom portion located within said abrasive grain layer, and
• in said step of polishing said spherical body, said spherical body being polished by coming into contact with said abrasive grain layer while being held in said holding layer in said groove portion.

A method for manufacturing a spherical member, comprising the steps of:

• shaping a ceramic powder into a spherical form;
• sintering said spherical form to produce a spherical body;
• and
• polishing said spherical body,
• in said step of polishing said spherical body, said spherical body being polished by a method comprising:
• arranging said spherical body to be processed between a first member having a first polishing surface and a second member having a second polishing surface opposed to said first polishing surface;
• and
• polishing said spherical body by applying a relative rotation to said first polishing surface and said second polishing surface while keeping said first and second polishing surfaces opposed to each other,
• at least one of said first polishing surface and said second polishing surface having a groove portion formed therein and extending circumferentially along said rotation,
• at least one of said first member and said second member having said groove portion formed therein including:
• an abrasive grain layer including an abrasive grain having a higher hardness than that of said spherical body, wherein said abrasive grain layer has a configuration in which said abrasive grains are bonded together with a bonding agent, and
• a holding layer formed on said abrasive grain layer and having a lower hardness than that of said abrasive grain layer, wherein said holding layer has, in a cross section perpendicular to a direction in which said groove portion extends, an arc-shaped wall surface, and said holding layer is formed of said bonding agent,
• said groove portion being formed to penetrate said holding layer in a depth direction and to reach said abrasive grain layer,
• said groove portion has a bottom portion located within said abrasive grain layer, and
• in said step of polishing said spherical body, said spherical body being polished by coming into contact with said abrasive grain layer while being held in said holding layer in said groove portion.