| 摘要 |
<p>PROBLEM TO BE SOLVED: To discharge foreign matter such as chips existing inside a hollow head part of an intermediate product of a hollow piston. SOLUTION: A piston main body member and a cap of a material 160 for manufacturing a single-head piston are fixed, and then plural parts including an outer peripheral face of a head forming part 208 are machined. Then an internal space of the head forming part 208 is cleaned before the outer peripheral face of the head forming part 208 is coated. The material 160 is dipped into the washing water in a state that a grasping claw of a working robot holds the material 160 in a state that through holes 130 are positioned at an uppermost part, and the material 160 is rotated around a straight line perpendicular to an axis of the material 160 after the washing water flows from the through holes 130 into the head forming part 208 to change its attitude to a state that the through holes 130 are located at a lowermost part. In this condition, the material is vibrated at a small angle around the straight line, and the ultrasonic vibration is applied to the washing water to discharge the chips or the like in the internal space from the through holes 130.</p> |
