| 摘要 |
A piston is manufactured with functional recesses (6, 7, 8) thereof formed from property improving material (18b, 18c, 18d). A blank (10) defines a mounting recess (12, 14, 16) and a quantity of said property-improving material (18b, 18c, 18d) is secured within said mounting recess. Said functional recess (6, 7, 8) is machined out of said quantity of property-improving material. The process for securing said property-improving material (18b, 18c, 18d) comprises forming a rod (20, 22, 34) from a material which on plasticisation under heat and pressure forms said property-improving material, inserting an end of the rod into said mounting recess, and rotating said rod in contact with a surface of the mounting recess (12, 14, 16), while applying force to the rod to feed it into the mounting recess. The rotational speed of said rod and the force applied thereto being controlled so that frictional heat is generated between the rod and the blank, causing plasticisation of the material of the rod, thereby, upon solidification converting it into said property-improving material (18b, 18c, 18d). |
