| 摘要 |
PURPOSE:To obtain a piston economically which maximizes the contact area in a ball part by molding a ball seat of a piston head by enclosing the ball of a connecting rod, and forcing the part near the neck of the ball to deform plastically in oil at a high temp. CONSTITUTION:A big end 4, a ball stud 3, and a ball 2 are assembled by welding or the like to form a connecting rod 1. The ball 2 of the rod 1 is loaded into a mold, and an aluminum material is charged in the mold to mold a piston head 5 by aluminum die casting in the state of enclosing the ball 2 therein, thereby forming a piston. The piston head 5 of such piston is immersed in oil 16 at a high temp. A rod 12 is inserted in a big end 4, a plate 13 is placed on the head 5, and tensile force F is acted between both to force the part near the neck of the ball 2 to deform plastically so as to exceed molding shrinkage, whereby a clearance 14 is produced in the bottom part of the ball 2. |
