| 摘要 |
PROBLEM TO BE SOLVED: To provide a cup type wheel capable of mirror finishing favourable in precision without generating unstable vibration on the wheel at the time of grinding and without leaving projections around the center of a back surface by using it for grinding of the back surface of a hard and brittle material of a silicon wafer, etc. SOLUTION: A cup type wheel on which cutting blades are installed in a ring shape on a peripheral wall end surface part of a cup type base metal constitutes a characteristic feature that a line forming a ring shape exists between a straight line connecting adjacent two points and a circumference of roundness concerning the points to equally divide the roundness in 4, 6, 8, 10 or 12 pieces and the two lines forming the ring shapes facing against each other with a center of the roundness between them are point-symmetrical with each other with the center of the roundness as a symmetrical center.
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