Patent ID: 7421782

Claim:
A method for manufacturing an internal combustion engine piston, the piston comprising a main cylindrical piston body, said main cylindrical body comprising: (i) a crown having: a top face having a circumferential edge disposed therearound; a pressure receiving recess formed within the crown, adjacent the top face thereof; an exterior circumferential face disposed adjacent the circumferential edge of the top face; an annular cavity for circulating cooling fluid disposed within the crown, between the pressure receiving recess and the exterior circumferential face, so as to encircle said pressure receiving recess; one or more grooves formed in the circumferential face for receiving a piston ring; and a lower portion formed integral with the exterior circumferential face, and (ii) a skirt, said skirt formed integral with and being a continuation of the lower portion of said crown; said method comprising: (a) forming an annular groove opening, for the purpose of creating said annular cavity, in the top face of the crown, between the circumferential edge of said top face of the crown and the pressure receiving recess disposed in said crown, thereby forming an annular groove having an inner wall in the crown between the pressure receiving recess and the exterior circumferential face, and an annular protruding strip having an end face defined by the top face of the crown between the annular groove and the exterior circumferential face, said annular protruding strip being formed integral with the top face and circumferential edge; and (b) applying pressure to said annular protruding strip, so as to bend said annular protruding strip in a direction of the annular groove, so as to close the annular groove opening, thereby forming an annular cavity operable to circulate cooling fluid.