| 摘要 |
PROBLEM TO BE SOLVED: To shorten the semi-sphere working time and have precise sphericity by positioning semi-sphere raw material between forging dies where a semi-spherical shape is precisely engraved in the internal surface, pressurizing the forging dies to be plastic-deformed, polishing the worked spherical semi-sphere raw material to be spherical, and then equally dividing the same into two parts to produce semi-spheres. SOLUTION: After a bar 100 fixed to a forging machine is first installed, a first forging die where a semi-spherical recess 115 is formed on the inside surface is inserted through one side end of the bar 100, a cylindrical semi-sphere raw material 120 is inserted through the other side end, and then further a second forging die 130 where a semi-spherical recess 135 is formed on the inside surface is inserted. Next, proper pressure is applied to a ram and an anvil and cold forging is performed at the ordinary temperature while the semi-sphere raw material is kept from being suddenly deformed with attention. The spherically worked semi-sphere raw material 120 is taken out and fins 125 are removed, grinding and lapping for working more finely for the sphericity is repeatedly executed for several times, and the the worked sphere is equally divided into two parts to manufacture a pair of semi-spheres 140. |
