Author : Mohan Kumar B N 1
Date of Publication :6th June 2017
Abstract: Resistance Spot welding system which is used for performing a welding process. The paper is divided into 3 sections. First, brief introduction of welding, methods of welding control such as resistance and spot welding is given. Secondly, the critical factor in the design of a welding process is dealt along with the principle of the welding process. Following this, the introduction to the design of the control scheme employed by us with the basic block diagram of the welding system and the functioning is presented. Finally, the conclusions is drawn along with its working and future improvements. The traditional approach in relation to spot welding machines is to use 50 Hz welding transformers. The drawback associated with these transformers is that they are both heavy and bulky. With the development of high power semiconductor switches and DC-DC converter topologies, it is now possible to develop inverter drive resistance spot welding equipment which can be operated at frequencies higher than the 50Hz frequency. The advantage of using high frequencies is the reduction in the size of the transformer. Automated resistance welding machines use micro-controller based control systems to regulate and ensure consistent welds. The design hopes to achieve complete automation of the resistance welding process. This is done by accepting various process inputs from the user and after due process, controlling various parameters like the current, conduction angle, weld count, etc.,. This is achieved by using a micro-controller, which will acquire data from the user and process it to generate suitable control signals as and when required during the welding process. The use of arm microcontroller makes the operation extremely fast, reliable and flexible. In the design, the most important parameter to be monitored and controlled is the primary welding current. For this constant current control method, an adaptive algorithm takes care of the past and present values, to predict the firing angles of thyristors in the next cycle, to ensure the present value of the current is maintained. The design and development of the control software algorithm is dealt with. Finally, the conclusions are drawn along with its working.
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