Patent GB-600036-A (GB)
Title: An improved automatic clamp for electric arc welding or cutting by hand
IPC: B23K9/133
Filed: 1945-07-25
Abstract: 600,036. Uniting and dividing by fusion. SOUDURE ELECTRIQUE AUTOGENE, SOC. ANON. July 25, 1945, No. 19097. Convention date, June 5, 1944. [Class 83 (iv)] In a manual arc welding or cutting apparatus in which the electrode is brought into contact by a spring with a motordriven feed roll and the electrode and feed roll are separated by displacement of a movable member relatively to the handle, the electrode sliding in contact with an electric contact member, the feed roll is arranged opposite to the contact roll and the outlet of the device to retain the end of the  electrode when it is no longer gripped by the feed roll. A spark guard 1, Fig. 1, is rigidly connected to a fixed fan 2 in the upper part of which a movable jaw 4 is pivoted at 3. A spring 9 secured at 10 to the spark guard normally keeps the jaws closed and a lever 5 pivoted to jaw 2 at 6 is provided to move jaw 4 away from the fixed jaw. On the upper end of the moving jaw is a plate 17 supporting a motor 18 which drives a knurled wheel 30 through its pinion 21, wheel 22, bevel gears 26, 27 and a shaft 28. The knurled wheel engages the covering of a metallic electrode which is bared along its length so that the blade 44 of a bronze contact 32 can make contact with the core, and the end of the electrode is further supported by a grooved pulley 31. An insulated handle 12 is adjustably secured at 15 to the fixed jaw by a bolt and wing nut; the handle forming a housing for the motor and welding supply cables and a mounting for an operating pressbutton 39. The motor feed cable 35 passes through this button switch and also a variable resistance 37 before it is connected to terminal 36, whilst the other cable 33 is* secured directly to terminal 34. In a modification, the spring 9 is dispensed with and a second handle is secured to the spark guard. This handle is also insulated and has a spring-pressed plunger which bears against the movable jaw 4 holding it closed. In a further modification, Fig. 6, a tubular jaw 3<SP>1</SP> contains the knurled wheel 30 which is driven in the manner before described and openings 64, 64<SP>1</SP> accommodate the electrode 40 and contact 32. The contact is secured to the end of a second jaw 2<SP>1</SP> whose extension 12<SP>11</SP> forms an insulated handle. A compression spring 60<SP>1</SP> ensures contact of the electrode and contact 32, its movement being limited by walls 62, 63. In this modification the clamp may have a handle formed from an extension of jaw 3<SP>1</SP> instead of 21 or two handles may be formed. In a circuit for automatic operation of the welding clamp, the secondary of a transformer 45, Fig. 4, is connected at one side to the work 58 and the other side passes through the current coil 55 of a relay 56 to the contact 32. A second transformer 49 has its secondary connected to a rectifier 50 from which on one side cable 52 is opened by the relay contact 56 and is connected to the electrode feed motor 18 ; the other side being connected to the motor through the variable resistance 37. As the supply is switched on by the press-button in the clamp handle, current passes through coil 55 starting the motor as contact 56 closes, and the welding rod is fed forward from its reel 59 as it fuses. Coated electrode for use with the feed mechanism may have grooves along one or both sides to contact the blade 44 or the covering may be eccentric to the core, leaving a part of the core bare. Elliptical electrodes having a coating over the ends of the major axis may also be used.