| 摘要 |
PURPOSE:To increase contact area between spherical bodies and an annular plate body by forming semiconductor concave parts on both inner and outer circumferential edges of the annular plate body. CONSTITUTION:An annular plate body 3A of a constant width is provided in its circumferential direction at constant intervals with circular multiple spherical body retaining holes 6. Semiconductor concave parts 9 are formed in positions radially corresponding to the spherical body retaining holes 6 on both inner and outer circumferential edges of the annular plate body 3A. Then, a spherical body 4 is placed on one side of the spherical body retaining hole 6 and part of the spherical body 4 is made to protrude out of the spherical body retaining hole 6 on the other side of the annular plate body 3A, and inner and outer circumferential parts of the annular plate body 3A where the concave parts 9 are formed are respectively bent in an approximate L-shape toward the spherical body 4 so that semicircular are edges 9a contact the spherical body 4. In this manner, contact area sufficient for preventing the spherical body from coming off even if there is springback of the annular plate body can be secured.
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