METAL PART FRACTURE MACHINE, CONNECTING ROD FRACTURE MACHINE, METAL PART FRACTURE METHOD, CONNECTING ROD FRACTURE METHOD, METHOD FOR MANUFACTURING METAL PART, AND METHOD FOR MANUFACTURING CONNECTING ROD

摘要

Using, as a half-split type mandrel 27 to be inserted into a through-hole 5a of a metal part and a connecting rod B, a semi-circular first mandrel 27a that comes into contact with a side surface of the through-hole having rigidity on the lower side and corresponds to the diameter of the through-hole and a semi-circular second mandrel 27b that comes into contact with a side surface of the though-hole having rigidity on the higher side and that has a radial dimension smaller than the first mandrel member, a correction for making the rigidity close to isotropic is performed and a crack that occurs in the metal part and the connecting rod is propagated along a target fracture surface α during fracturing.