| 摘要 |
PROBLEM TO BE SOLVED: To obtain a manufacturing method for easily manufacturing a high-precision ring 8a which is a material for manufacturing a race forming a radial ball bearing by cold working. SOLUTION: A cylindrical third intermediate material 16 shown in (D) is manufactured of a billet 13 shown in (A) through a first intermediate material 14 shown in (B) and a second intermediate material 15 shown in (C). The third intermediate material 16 is compressed in an axial direction until an axial dimension coincides with the axial dimension of the high-precision ring 8a. An excess thickness part exceeding the capacity of the highly accurate ring 8a is a fourth intermediate material 21 shown in (E) whose inner peripheral surface is inwardly swelled in a radial direction to be released. After that, the excess thickness part is collected in one end in the axial direction by drawing so as to form a fifth intermediate member 24 having an inwardly collar-shaped excess thickness part 23 shown in (F). Finally, the excess thickness part 23 is removed to form the annularly-shaped high-precision ring 8a whose inner diameter, outer diameter and axial length are regulated in values. COPYRIGHT: (C)2006,JPO&NCIPI
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