| 摘要 |
PURPOSE:To improve the abrasion resistance of a cylinder by forming a partially quenched layer in a prescribed pattern by irradiating the laser beam onto the inner peripheral surface of the cylinder which is formed from the quenchably metal. CONSTITUTION:A sleeveless cylinder is formed out of quenchably metal, and a partially-quenched layer with a prescribed pattern is formed onto the inner peripheral surface of the cylinder through the laser beam irradiation. Therefore, the nonquenched part 22 is selectively worn out by a piston during the engine operation, and an exceedingly minute step difference is generated between the nonquenched part 22 and the quenched part 21. Then said step difference serves as the reservoir of a lubrication oil, forming an oil film, whereby the abrasion resistance of the inner surface of the cylinder hole is improved. |
