| 摘要 |
A piston bottom for large capacity internal-combustion engines is made by forging a saucer-shaped blank from refractory-forging steel and then in a second forging step transforming the saucer-shaped blank into a cup configuration with a planar rim of the blank being transformed into a cylindrical shoulder and an annular bulge of the blank being transformed into an annular boss for connecting the piston bottom of the cylindrical body of the piston. The blank has a convexity projecting on one side of the blank opposite that formed with the bulge.
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