MANUFACTURING PISTONS

摘要

A piston for use in an internal combustion engine is manufactured by forming a blank (10, 50, 70) from a first material, providing a region (20, 60, 80) of a second material in a surface portion (12, 52, 54) of the blank (10, 50, 70), the second material being secured to said first material, and forming a recess (14, 28, 56, 68, 86) so that the recess has a bounding surface at least part of which is formed by the second material. The region (20, 60, 80) of the second material is formed and secured to the first material by inserting a tool (22) into the blank (10, 50, 70), bringing about relative reciporcating movement between the tool and the blank (10, 50, 70) so that frictional heat is generated plasticising the material adjacent to the tool, and by causing relative translational movement between the blank and the tool while continuing the reciprocating movement therebetween so that the tool (22) moves through said region (20, 60, 80), thereby forming the second material and mixing it with the first material at the edges of said region to secure the materials together.