Patent GB-183787-A (GB)
Title: Improvements in and relating to electric arc welding applicable for welding studs, tubes and the like to or into metal plates, bodies and the like
IPC: B23K9/20
Filed: 1921-01-19
Abstract: 183,787. Steele, L. J., Martin, H., and McCarthy, A. E. Jan. 19, 1921. Welding.-In an apparatus for welding iron, steel, or brass studs, tubes, &c. to metal bodies such as sheets, plates, bars, blocks, forgings, or castings, for making cinematograph, fishing, and other reels, umbrella and stick ferrules, and parts of motor road vehicles, aeroplanes,' ships, electrical apparatus &c., of the kind in which an automatically-controlled electric arc is maintained for a predetermined period of time between the stud and the plate, and the stud then forced against the plate to complete the weld, the stud is withdrawn electromagnetically by a shunt or series solenoid to strike the arc and is returned to the plate by fluid pressure. In the form shown in which the arc is struck by a shunt solenoid and the stud returned by air pressure, the stud is secured to a chuck 13 attached to the core 12 of a solenoid 1, which is mounted together with a non-magnetic wall 5 and a casing 6 between plates 3, 4 which are secured together by bolts 7 passing through distance-tubes 8. Rotation of the core is prevented by grooves 19 and one or more guide plates 20 and the welding current is supplied to the stud from leads 23 to a brass plate 21 which is mounted underneath a steel plate so as to shield the arc from magnetic effects of the solenoid. The core is tapered at its upper end and is screwed on and fixed by a grub screw to a non-magnetic pistonrod 11, which is shouldered and secured to the piston 10 by lock-nuts. The lower end of the cylinder, which is either screwed to a flange on the plate 3 or secured thereto by a number of lugs and screws, is either open to the atmosphere on its underside or has a plate 18 either perforated or fitting loosely round the piston-rod. A spring 15<1> is provided to cushion the piston to ensure good contact between the stud and plate prior to striking the arc. The length of the arc is adjustad by a spring plunger 16 carried by a screwed plug 15, the head of which is embraced by a bracketlike member 17 for determining the extreme positions of adjustment of the plug. The valve 28 which is pressed down by a spring 37 and is connected to the core 36 of a solenoid 31 connects the port 27 either to the air-supply port 38 or to the atmosphere at 39, and a port 40 is provided to permit escape of air trapped by the valve. The air may be admitted to the cylinder through an orifice of small dimensions. The electrical arrangements are similar to those described in Specification 156,836. To start the operation a block provided with four plugs 54, Fig. 5, respectively connected to one terminal of the solenoid valve 31, push-button switch 53, pushbutton switch and one terminal of the arc-striking solenoid 6, and the other terminal of the arcstriking solenoid, is inserted in the sockets 55 and the push-button is operated, causing current to pass through a circuit in parallel to the main welding circuit by way of a solenoid 47, contact 48, second plug, third plug, framing at 56 and thence from framing at 51 by way of the fuse 52 to the negative lead. The operation of the solenoid releases a brake from a motor-driven shaft 50, which is thus set in motion. When the shaft rotates a gap in the cam 49 which is normally opposite the contact 48 moves away therefrom so that the solenoid circuit is now completed independently of the plug switch, through the contact 48, cam 49, and framing at 51. A cam 59 next engages a contact 58 and allows a current to pass through the coil 57, contact 58, cam 59, framing at 51 back to the negative terminal and so energizes the coil 57 to close the main welding switch 42. A supplementary switch 60 is simultaneously closed and causes current to pass through non-inductive resistance 61, fourth plug, solenoid 6, third plug, framing at 56 and back to the negative terminal so as to strike the arc When the cam 63 engages the contact 62, the current through the resistance 61 returns by way of the contact 62, cam 63, and framing at 51 and so short circuits the solenoid 6 which is thus deenergized. At the same time the cam 66 engages the contact 65 and so allows current to pass through the first plug, solenoid 31, resistance 64, contact 65, and cam 66, back to the negative terminal so as to energize the solenoid 31, which is raised to allow air to return the stud to the plate to complete the weld. When the cam 59 and contact 58 are disengaged the switches 42, 60 are opened to cut off the welding-current, open the circuit of solenoid 6, and also the short circuit and de-energize the solenoid 31, and when the cams 63, 66 are released from the contacts 62, 65 the short-circuit ot the solenoid 6 is removed and the circuit of solenoid 31 additionally opened. When the gap in the cam 49 comes opposite the contact 48 the solenoid 47 is de-energized to stop the machine. The contact 58 is weighted and is vertically adjustable. The adjustment of the contact to regulate the period of the arc is effected by a cam attached to a spindle having a graduated dial on its outer end rotating in connection with a fixed pointer on the casing. In a modification of the apparatus shown in Fig. 5, the solenoid 6 is not short-circuited but is overcome by the air-pressure. The electrical arrangements are similar to those shown in this Figure except that the cam 63 and contact 62 are omitted. The stud-moving and arc-striking apparatus may be attached to, but insulated from, a movable spindle or slide such as that of a drilling-machine. When welding long bars or tubes the stud-holder may either be secured to a hollow piston-rod or to a parallel hollow rod sliding in guides and connected to the piston-rod by a lever or to a pair of parallel piston-rods by a cross-bar. When welding iron or steel studs, brass rings or bushes are fitted on the studs, the ends of the studs projecting beyond them to steady the arc. The ends of the studs may also be hollow. A disc or ball of brass or other metal may be placed between the stud and the plate before welding to prevent the stud sticking to the plate when the circuit is first closed, or to vary the quality of the welding.