Patent GB-196322-A (GB)
Title: Improvements in and relating to electric arc welding applicable for welding studs, tubes or the like to or into metal plates, bodies and the like
IPC: B23K9/20
Filed: 1921-11-24
Abstract: 196,322. Steele, L. J., Martin, H., and McCarthy, A. E. Nov. 24, 1921. Welding.-In a method of automatically and electrically welding iron, steel, or brass studs tubes &c. to or into cast or forged metal sheets, plates, bars, or blocks, the stud or tube is set at a determined distance from the body and an electric arc formed and maintained for an automatically-controlled period, the stud or tube being forced home by fluid-pressure means while the current is maintained. To start the arc, the studs, &c. may be provided with fusible pins, or a high-tension discharge used. The stud-moving device, Fig. 1, comprises a cylinder 1 containing a piston 2 carrying a hollow chuck holder 6 provided with an adjustable, conical member which engages the chuck 13 and carries an insulating-disc 15. The cylinder cover 16 carries an adjustable, screwed plug 17 with a spring-pressed plunger 18 which gives a visible indication when the piston 2 engages the plug 17. A casting 20 on the cover 16 is secured to and insulated from a sleeve 21 carried by the spindle of a drilling-machine. Friction blocks 48 normally hold the piston-rod raised, and are connected to laminated strip current lead 51. The valve 29 is provided with a hand knob 35, and is pressed down by a spring 32 and raised by a solenoid 31. The valve-chest is provided with inlet and outlet passages 39 and 37, 38 respectively, and a cylinder passage 36. Preparatory to welding, the stud-holding device is so mounted that the piston 2 touches the plunger 18 and the pin 54, Fig. 3, the plate to which the stud is to be welded. Control and timing apparatus, similar to that described in Specification 156,836 and including improvements described in Specification 183,787, is shown in Fig. 4, or apparatus as described in Specification 183,161 may be used. The apparatus is started by a switch 57 connected to a multiple plug 58 which energizes the brake solenoid. The cam shaft 60 rotates, cam 63 closes the circuit of the coil 62 thereby closing the main circuit through the stud 53, and the current fuses the pin 54 and strikes an arc. When the arc has passed a time determined by the setting of the contact 64, the cam 65 engages the contact 66 and the solenoid 31 is energized to move the valve 29 to admit air to the cylinder 1 to press home the stud 53 which becomes welded to the plate. When the contact 64 disengages the cam 63, the main circuit and the auxiliary, valve-solenoid circuit are de-energized. The air-pressure in the cylinder 1 may be maintained by a dash-pot uevice beneath the valve 29, retarding its downward movement, or by omitting the spring 32, the valve being closed by hand. When the gap in the cam 67 confronts the contact 68, the brake solenoid is de-energized and the shaft 60 stopped. The machine spindle is then unlocked and raised, and the stud-holding device withdrawn. The pieces 54 may be formed on, inserted in, or welded, brazed, or soldered to the conical end of the stud 53, or may be formed on fusible caps thereon. The piston-rod may carry the device shown in Fig. 5. In the holder 69 slides a spring-pressed plunger 70 the downward movement of which is limited by an adjustable disc 72. This construction permits the striking of a. long arc by using a long pin 54, which arc is subsequently shortened. The spring 71 cushions the impact between the pin and the plate. Metal-splashing during welding is avoided by advancing the piston 2 slowly by throttling the supply at an orifice 75 in the union 40. A uniform distribution of current in the plate to which the stud is welded is ensured by supplying the current from a copper or brass block raised above the machine table and in line, with the stud. An air receiver is arranged between the air-main and the apparatus. Fig. 6 shows another method of control which permits of the instantaneous striking of the arc upon the actuation of the starting-push-button, and wherein another form of timing-device is used in which at the end of the desired time the completion of the weld is automatically effected by the movement of the stud to the plate followed immediately by the opening of the main welding-circuit. A throw-over switch 76 operated by two solenoids 77, 78 is provided, and is initially in series with one of the solenoids 77 which is energized on closing the control switch 79. The switch 76 is then thrown over, the coil 77 de-energized, the main circuit is closed and the arc struck, and the timing apparatus, of known type, is set in operation by the circuit of solenoid 81. The core of solenoid 78 is also withdrawn. The circuit of the valve solenoid 82 is closed when the contact 83 is engaged, and immediately after the contact 84 is engaged thereby energizing the solenoid 78 and throwing over the the 76 to the starting position thereby breaking the main circuit and the circuit of the timing apparatus solenoid. In lieu of a pin 54, the stud 53 may be set from the plate and a high-tension discharge from a suitable magneto or coil passed across the gap as the main welding-circuit is closed. Alternating currents may be used with the above apparatus. In a modified chuck holder, a spring-pressed, longitudinally-grooved, conical sleeve surrounds the chuck which is prevented from rotating. In another holder, a mercury cup is provided to ensure electric contact.