GB637146A - Improvements in gas blanketed arc welding - Google Patents

Abstract

637,146. Uniting by fusion. LINDE AIR PRODUCTS CO. Feb. 17, 1948, No. 4578. Convention date, Feb. 28, 1947. [Class 83 (iv)] Intermittent arc welds are made by directing an inert gas blanketed non-consumable electrode to a zone of the work striking an arc between the electrode and a central portion of the zone maintaining the arc until the work fuses and maintaining the electrode and. the zone of gas stationary for the duration of the arc. After the gas is turned on the arc is struck after a predetermined time interval. The torch comprises a holder 10 with grip G for electrode E and an inert-gas tube 14 supplying a ceramic cup 20. A metallic cover 21 is supplied with cooling water by pipe 25, tube 26 and flexible pipe 27. An electric cable 34 is soldered to a pipe 32 which exhausts the cooling water and supplies the welding current. A trigger T controls a switch K of a timing device. A timer 37 in series with the switch K controls the inert gas supply. When the switch K is closed by trigger T a solenoid valve 40 is operated through normally closed contacts 38 to turn on the gas supply to a tube 24 and to start the timing period of the timer 37. After an interval the timer 37 closes contacts 39 and through closed contacts 48 of a weld timer 47 energizes a relay 41 to close contacts 42 of a welding transformer 43. The welding circuit includes a H.F. starting unit R which establishes the arc and permits current to flow through the electrode E and the work U. The welding current energizes a relay 45 to close contacts 46 of the weld timer 47 which times the duration of the weld. After the time interval relay 47 opens contacts 48 to de-energize relay 41 to open contacts 42 to de-energize the transformer 43. The weld timer 47 at the same time closes contacts 49 in parallel with contacts 46 of welding current relay 45 to reset the timer. Gas continues to flow until the timer 37 opens contacts 38 to operate the valve 40. Release of the trigger T opens the switch K which resets the timer 37. A switch 50 may be employed to cut out manually the timer 47 in which event the duration of the weld is governed by the length of time the trigger T holds the switch K closed. In a modification, Fig. 4, not shown, the electrode is advanced through the nozzle to locate the weld and is then retracted, the nozzle is pressed into contact with the work and the gas and welding current are turned on in timed relation to the pressure of the nozzle on the work.