NEW DESIGN OF COLD WIRE FEEDER FOR COLD WIRE ADDITION TECHNIQUE IN SUBMERGED ARC WELDING PROCES

摘要

The present invention provides a new configuration of the wire feeder which can simultaneously use multi wires in two different nozzles at different feed rates for different current rating. This new wire feeder substantially enhances the production rate compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the existing DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same heat in-put energy available in the arc zone. Additional power source and control means is not required for this new wire feeder. This new wire feeder is easily interfaceable with the existing SAW machine. With new cold wire system, the results of radiographic test, Ultrasonic test for the test plate are found satisfactory as per code IBR and ASME Sec IX. The present invention is directed to a further development that the dissimilar wire combination is fed using a single wire feeder with two nozzles drawing power from a single power source with parameters of 425 A, 28 V and 0.5 m/min as welding speed. The present invention creates a single weld pool in which the required weld chemistry can be obtained from the use of two wires of different chemistry. This results savings in consumables cost, cycle time reduction and high productivity. The improved cold-wire feeding device of the invention has a plurality of welding wires electrically coupled to a source of electrical energy. Welding wires of different chemistry are being fed in a single wire feeder with two nozzle drawing power from single power source. A common weld pool is created in which the flux is analytically neutral. The weld metal structure is produced with a high proportion of acicular/martensetic structure. The surface proportions of acicular / martensetic is 100 percent. According to the invention, a single pass welding is performed, and buffering layer of welding and machining is avoided. Preferably, a multi layer pass welding is performed for reducing the number of layers compared to the conventional SAW process to enhance the mechanical properties.