GB1141084A - Process for the production of a piston blank - Google Patents

Abstract

1,141,084. Making pistons; forging; extruding. MAHLE K.G. 11 Aug., 1967 [17 March, 1967], No. 37019/67. Headings B3A, B3H and B3P. In a process for making a pressed piston blank having a light metal body and a ring carrier embedded therein of a material having greater hardness at higher temperatures, a preliminary body 10 corresponding approximately to the desired piston form is pressed from a light metal slug so that at its head end the diameter is reduced to the internal diameter of the ring carrier and parts protrude axially beyond the final crown surface. A ring-carrier blank 30 is shrunk on to a shoulder 14 formed at the transition to the reduced diameter head end, so that it is non-displaceable on the preliminary body. The preliminary body is then placed head downwardly into a second pressdie and a plunger 43, corresponding in form to the internal shape of the blank forms the piston crown in co-operation with a bottom insert 42 and die liner 41. As the plunger 43 forms the piston crown it forces the carrier blank 30 downwardly in the die until it abuts a shoulder 45 in the liner 41. The piston blank is finally machined to size and a ring groove formed in the blank 30, which may have irregular depressions formed in its surface into which the piston material is forced, Fig. 5 (not shown). The piston body may be of aluminiumsilicon alloy containing more than 12% silicon and it is formed at about 480‹ C. The ring carrier blank is heated to 450-500‹ C. before it is placed on the preliminary body, which is thereafter heated to this temperature range so that the part 13 expands and presses itself against the blank 30, its surface partly penetrating into the depressions on the latter.