GB1278011A - Improvements in or relating to stud-welding apparatus - Google Patents

Abstract

1278011 Welding by pressure GEORGE TUCKER EYELET CO Ltd 19 April 1971 [7 Feb 1970] 5987/70 Heading B3R A stud welding tool comprises a housing 10 including an abutment 12 for engagement with a workpiece W, a stud holding chuck 32 reciprocable in the housing between a rearward position in which it receives a stud S fed transversely of its axis through an opening in the housing, and a forward position in which a stud held thereby is presented for welding with its end projecting beyond the abutment, the chuck 32 comprising resilient fingers 34 which provide a pocket in which a stud can be gripped, and means for holding the fingers apart when the chuck is in the rearward position to facilitate insertion of the stud into the pocket. Reciprocation of the chuck is effected by a pneumatic piston and cylinder unit 20, 15. A plunger 56 located in a bore of the chuck has a rounded end which co-operates upon rearward movement of the chuck with cam surfaces 38 on the chuck fingers 34 to effect the opening of the fingers; the plunger abuts a rod 54 which passes through a bore in the piston 26 and itself engages an adjustable stop 58, adjustment of which (by screw 64) determines the position and extent of opening of the fingers. To effect welding of the stud to a workpiece W the tool is pressed against the workpiece to engage the abutment 12 therewith, the chuck and stud together with the cylinder and piston unit 26, 15 being thereby pushed back against the pressure of a spring 18; this initiates the action of a solenoid (not shown) which temporarily retracts the chuck to strike a pilot arc. As the stud is forced back against the workpiece by the pressure of a spring 18 full welding current is discharged from a capacitor discharge unit. The studs are fed to the tool by compressed air from a hopper and separating mechanism through a flexible hose 72 having a T-shaped feed passage leading to a similar passage 74 in a block 76 mounted on the tool. Admission of air to the cylinder 15 to retract the piston 26 for insertion of a fresh stud for welding is not initiated until the tool has been removed (thereby breaking the welding circuit) from the previously welded stud.