To restrain distortion in breaking when the connecting rod being e.g. automobile engine parts is broken and divided to form a cap part and a rod part.
The connecting rod W made from cast iron provided with a big end part B and a small end part is integrally formed, notches are formed in a prescribed part of the combining hole of the big end part B with a laser beam machining, thereafter a pair of expansion tools 1 is inserted into the combining hole, a wedge 2 is inserted into the wedge inserting recessed part of expansion tools 1, and a iron ball 14 is fallen from the upper side of the load receiving surface 2a of the wedge 2. Therefore, a shocking point load is applied onto the load receiving surface 2a toward the central part of the wedge 2, thereby breaking and dividing.
MURAKAMI JUICHI
KODAMA HARUKI
MATSUE YASUTAKA
IKEDA HIDEAKI
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