STRENGTHENING METHOD AND STRENGTHENING TOOL FOR OIL HOLE OF CRANKSHAFT

摘要

PROBLEM TO BE SOLVED: To obtain necessary fatigue strength by plastically deforming a chamfered part and a cylindrical part with a simple process.SOLUTION: A strengthening tool for an oil hole of a crankshaft includes: a column part 32; a diameter-reduction column part 33 having a diameter smaller than that of the column part 32; and a truncated cone part 34 of which diameter is gradually increased from the diameter-reduction column part 33 toward an axial direction, from the tip side thereof. The column part 33 has a curvature radius larger than the oil hole 16 before forming by 5/100 to 20/100 mm.SELECTED DRAWING: Figure 3