| 摘要 |
PURPOSE:In crank shaft manufacturing method for relieving concentration of stress at the joint of crank pin and crank arm, to eliminate concentration of stress by forming smooth finish face continuously on the crank arm at the circumference of crank pin. CONSTITUTION:A rotary cutter is inserted between crank arms 2 to cut the innercircumferential casting face 5a of recessed section 5 entirely to the finish face 5b. Since said face will be continuous with the circumferential finish face 3b of crank pin, step 7 between said face 3b and said section 5 can be eliminated to produce a crank shaft having high fatigue resistance. |
