摘要 |
A closed cavity piston of this invention includes an elongated piston body and a separately formed piston cap having an elongated stem and head thereon. The body includes a closed end and an open end with a cavity having a bottom wall adjacent the closed end and an outer wall terminating in a rim at the open end. The stem of the piston cap is friction inertia welded to the bottom wall of the piston body and the head of the piston cap welds to the rim of the piston body. The stem of the cap is inserted into the cavity of the body until it engages the bottom wall. Then the cap is friction inertia welded to the body at the stem/bottom wall and head/rim interfaces after preheating.
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