| 摘要 |
PROBLEM TO BE SOLVED: To improve assembling accuracy of both by forming a material with a rod body and a cap integrated together, dividing it with its treated at low temperature, returning it to a normal temperature, and brushing the divided surfaces. SOLUTION: A connecting rod material 4 is cold-forged from a preformed material 3, end faces of large and small end parts 5, 6 are ground, the inside face of the large end port 6 is ground, and notches 7 and connecting holes 8 are machined. The material 4 is suspended, and the large end part 6 is dipped in liquid nitrogen in a low-temperature treatment vessel 9 to be fractured and divided into a rod body 1 and a cap 2. Then, the both of them are laid on a pallet 12a circulating in a temperature-raising treatment vessel 12 having hot water put therein to be returned into a normal temperature, and the divided faces are brushed by a nylon brush 13 with abrasive grains to remove fine projections to be easily chipped off. The divided surfaces are cleaned and air blown, the cap 2 is fastened to the rod body 1 via the connecting holes 8 by a bolt 14, a bush is press fitted into the small end 5, and the bush and the inside face of the large end 6 are finished. This constitution can improve the assembling accuracy.
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