| 摘要 |
Heavy duty piston and method of making the same, the piston including confronting wrist pin boss portions, the walls defining the inner extremities of the boss portions being convergingly inclined toward the head of the piston, and the boss portions having recessed portions formed therein of a contour such that the metal grain flow lines surrounding the recessed portions are at least partially circular in the area of the wrist pin holes which are formed in the bosses. |
