| 摘要 |
PROBLEM TO BE SOLVED: To efficiently work a raw spherical material without generating a damage by grinding the raw spherical material with a grinding wheel, which is provided along the inner peripheral surface of a rotary container, so as to work the raw spherical material into a spherical material. SOLUTION: When a rotary container 4 is rotated around a rotary shaft 3 by a driving means 6 in the condition that a raw spherical material is thrown in the rotary container 4, the raw spherical material is repeatedly lifted to the predetermined height and fallen inside of the rotary container 4. The raw spherical material is ground by grinding wheels 5, 5A, which are provided along the inner peripheral surface 41 of the rotary container 4 and the outer peripheral surface of a cylinder part 43, and worked into a spherical material. At this stage, since the raw spherical material is ground in the free condition, the raw spherical material can be worked into a spherical material without generating a crack, a breakdown and a damage even in the case of the raw spherical material, which is made of the hard fragile material and the soft ductile material. After concluding the working, it is unnecessary to sort a spherical material and the media. Grinding of the raw spherical material can be thereby efficiently performed. |
