GB490339A - Improvements in or relating to automatic electric arc welding - Google Patents

Abstract

490,339. Uniting by fusion. ELIN AKT.-GES. FUR ELEKTRISCHE INDUSTRIE. Nov. 29, 1937, No. 32974. Convention date, Nov. 30, 1936. [Class 83 (iv)] In automatic electric are welding with short electrodes, preferably flux coated, successively connected end to end, the connection is effected by welding by an arc struck between the ends in series with the main welding are. The current may be conducted to the electrodes by slotted plates 4 engaging optionally spaced bared spots in the electrodes and also engaging conductor rails 5, 6 which also keep the ends of the electrodes in alignment. The electrodes may be fed by rubber covered or milled edge wheel 7 or by driving the plates 4. Fixed, adjustable, or resilient guide roll: 8 also are provided The rail 6 is perman ently connected to one end of the current source and the rail 5 througl a switch 12. When the switch is opened current passes to the work 1 through elec trodes 3 and 2 and the electrode 3 is retardec by a lever 11 actuatec by an electromagnet 10 to strike an are between the electrode ends. On releasing the electrode 3 it is forcec forward by hand, grav ity or a spring to com plete the weld. The plates 4 may be removed from the electrodes by hand or by a peg wheel 9. Pins, plates, sleeves, ferrules, &c. may be at the same time welded between the ends of the electrodes for application of the feed or current supply. The electrodes may alternatively be kept in alignment by separate guide rails or nozzles. The welding operation between the ends of the electrodes may be initiated automatically, e.g. by means of a contact wheel rotating in dependence on the electrode feed or by a contact operated by the electrodes themselves. In one form, Fig. 3, a number of electrodes 24, with grooved coatings, are pressed by springs 26 against the inner wall of a magazine 25 and the operative electrode 22 is fed forward and current supplied thereto by a screw 27 rotated by a motor controlled by a coil connected across terminals 35, 39 to avoid trouble when the second arc is struck. The grooves in the coating may be cut previously or by a cutting screw coaxial with the screw 27 as described in Specification 488,524. The electrode is guided by rollers 36 and nozzles 37, 38. Welding current is initially supplied from terminal 34 through contactor 33, brush 32, and slip ring 31 to electrode 22, the work being connected to the terminal 35. When electrode 22 leaves the magazine, the next electrode 23 connects contacts 41, 42 and 43, 44 and so connects a current preferably through an auxiliary supply from terminals 47, 48 so as to energize coil 46 and thus cut out the contactor 33. Current then passes from terminal 34 via spring 49 and contact 59 to electrodes 23, 22 and then through the arc to the work. Movement of the electrode 22 then strikes the arc between the electrodes. When the arc tension reaches a certain value, a coil 51, energized by current from terminal 34 through spring 49 and brush 32 so that it is in shunt across the arc between the electrodes, attracts armature 52 against the back pressure of a spring 53 and adjustable dash pot 54 so as to withdraw a catch 56 and thus release the spring 49 which moves forward to advance the electrode 23 to weld it to the electrode 22. Contacts 41, 42 are thus allowed to open so as to break the circuit through coil 46, thus allowing contactor 33 to close to resume normal welding. Immediately before the upper end of the electrode 22 leaves the magazine contacts 43, 45 are closed so as to energize coil 57 through current from terminals 47, 48 and thus the spring 49 is retracted and re-set.