Patent ID: 11925972
Assignee: NATIONAL UNIVERSITY CORPORATION TOKAI NATIONAL HIGHER EDUCATION AND RESEARCH SYSTEM
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 3:
4. The precision forging method according to claim 2, wherein the wall portion is a circumferential wall, wherein when an amount of the circumferential wall cut by the first punch is expressed by t0 mm, a length of the punch in the second direction is greater by 2t0 mm than an inner diameter of the circumferential wall, wherein the pre-working projecting wall has a thickness tc0 that satisfies 0.1 mm≤tc0≤20 mm, wherein in a joint line between the circumferential wall and the pre-working projecting wall, the joint line located at a side of the pre-working projecting wall opposite to the punch has a radius of curvature expressed by rcp that satisfies rcp/tc0<2.0, and wherein the metal material is worked so that t0/tc0 satisfies

t0/tc0≥0.052rcp/tc0+0.23.