Research On AC Submerged Arc Roll Surfacing Welding Process And Equipment

Mill rolls are important components of steel rolling and non-ferrous metal rolling equipment. As the most important consumable parts, rolls especially large rolls are very expensive. Rolls usually work in poor conditions, they wear and age commonly. Once the roll is damaged or its diameterdue can’t satisfy working requirements, it must be scraped. Roll repair and remanufacturing has become most important thing of metallurgical enterprises,which brings lots of attentions.The AC submerged arc surfacing welding method is one of the best soutions.From a technical point of view, this thesis confirms the relationship between waveform control and roll repair by AC submerged arc surfacing welding. The study on controllability of AC submerged arc welding has obvious advantages to adapt the complexity and diversity of roll surfacing and could meet higher roller repair quality,which is also the basis and prerequisite to design the AC submerged arc roll surfacing welding unit.Based on the analysis of the relationship between AC submerged arc welding waveform control and roll surfacing welding process, high-power single inverter welder main circuit and FPGA based digital control were designed.Corresponding conclusions were proposed by the analysis of AC current zero rearc technology. In view of saving energy, the main parameters of the welder were calculated and optimized.And the trial-produce prototype has reached relevant energy efficiency rating requirements.The control syetem of welder is based on the FPGA digital control system. Through building Nios Ⅱ soft-core, the welding parameters storage and recall, transaction execution and coordination were realized. Meanwhile, By constructing FPGA based PI calculation module and PWM module the inverter is controllable. The SOPC system has not only realized the flexibility of the design, but also improved the operation speed and control accuracy of the whole system.Through prototype debugging and testing, the propsed design can meet actual operating requirements。 And furtherly the relationship between AC current parameter adjustment and roll welding process had explored by the welding test result of the prototype. The designed AC submerged arc welding equipment is suitable for roll surfacing.