GB678570A - Improvements relating to electric welding apparatus - Google Patents

Abstract

678,570. Welding by pressure. ENGLISH ELECTRIC CO., Ltd. Dec. 8, 1950 [Dec. 9, 1949], No. 31684/49. Class 83 (iv). In a stud welding gun having a body member and a stud carrier member movable relatively to the body and biased towards the work, an electromagnet is provided having a core and a coil on one member and an armature on the other, the armature being unable to move relatively to the other member in the direction of carrier movement but being capable of movement to engage the core frictionally so that it is clamped magnetically thereto to retain the carrier in any position. A stud 9 with a fusible extension 9a is pressed on to the work until a tripod 3 also engages it, thus sliding against a spring 10 a spindle 6 carrying a piston, comprising a core 11 and a coil 14 in a groove therein, into the body 1 which mounts a three-part armature 12 movable only radially. Contacts 15 for the coil 14 engage spring-loaded contacts 16 connected to a D.C. supply through a timer also controlling the welding current and operated by a switch 18 in the handle 2 which switch is then pressed. The coil 14 is energized and the armature 12 is attracted to the core 11 while the welding current fuses the extension 9a. The timer operates to de-energize the coil 14 and cut off the welding current, the stud being forced into the molten work by the spring 10. To increase the reluctance of the magnetic circuit, a radial air-gap is provided between the lower end of the core 11 and the armature 12. The Provisional Specification describes non-magnetic spacing- rings positioned between the armature members 12 and the bore of the body 1. Reference has been directed by the Comptroller to Specification 579,711.