| 摘要 |
1,181,619. Welding by pressure; making pistons. CATERPILLAR TRACTOR CO. 4 Oct., 1968 [9 Oct., 1967], No. 47242/68. Headings B3A and B3R. [Also in Division F2] An internally cooled piston has a coolant sealed in a cavity in the piston head by means including a friction weld. A piston assembly 35, comprising a crown portion 39 furnace brazed to an annular skirt 37 and to a rod strut 41 having a hollow bowl portion 43 forming with the crown portion a cavity 45, is clamped in a non-rotatable chuck on the tailstock of a friction welding machine, a stainless steel rod 51 machined with a taper 53 is clamped in the rotatable chuck of the welding machine and a sodium-mercury cooling mixture 49 is inserted into the cavity 45 through a filler hole 47 in the rod strut 41 which filler hole has a taper identical to that on the rod 51. The spindle on which the rotatable chuck is mounted carries flywheel weights and is driven by an electric motor through an hydraulic pump and motor until a predetermined velocity is obtained, the motor is disconnected or shut down and the tailstock is moved towards the rotating chuck by a ram so that the rod 51 becomes friction welded in the filler hole 47. The excess rod material is machined away leaving the piston sealed. In a modification the filler hole is provided in the crown portion of a similar piston and is similarly sealed by friction welding a rod therein. A heatresistant deposit is welded over the machined plug. In yet another modification not employing a filler hole the strut member is clamped vertically in the non-rotating chuck, the cooling agent is placed in the bowl of the strut and the crown portion having the skirt already frictionwelded thereto is clamped in the rotating chuck of the friction welding machine and frictionwelded to the strut member to seal the coolant in the piston. |
