| 摘要 |
PURPOSE:To prevent abrasion and/or breakage of a side washer while preventing falling-off of a crank pin by hardening only the interior face of a crank arm. CONSTITUTION:After fitting a cementation preventive pipe to a shaft part 22 of a crankshaft 11, said crankshaft is plated with copper to form a copper coat 25 for preventing cementation. Then, the pipe 24 is drawn out and the coat 25 is removed by cutting except a part positioned in the vicinity 13a to the fringe of a crank pin hole 13. Through subsequent cementation treatment, the surface A of a part which is not covered by the coat 25 is cemented and hardened. The coat 25 is then removed through solution by means of solvent liquid. |
