| 摘要 |
PROBLEM TO BE SOLVED: To improve precisions of surface roughness, cylindricality and roundness of a trial ring of shell shaped needle roller bearing. SOLUTION: After an iron punch 20 is inserted to contact a bottom of a deeply drawn cap shaped shell material 10 and press the cap shaped shell material 10 into a dice hole 31 of a dice 30 keeping the ironing punch 20 inserting, an inner periphery surface 2 of a cap shape is ironing treated by drawing an ironing punch 20.
|
