Study On Current Parameters Information Monitoring And Analysis For Resistance Spot Welding

Resistance spot welding with its simple metallurgical process, the shorter heatingtime, low cost of welding, good working conditions and production efficiency hasbeen widely used. At the same time, the requirement on the quality of resistance spotwelding has been increasingly improved. Therefore, how to improve the joint qualityand reliability of the resistance spot welding has become the focus. In addition tostrengthening the management, how to improve the quality monitoring technology forresistance spot welding has become a priority.Resistance spot welding is a very complex process, there are many externalfactors and internal factors which influence each other. There are too manyunpredictable causal factors to interference at the same time, which caused greatdifficulties to the quality monitoring for resistance spot welding. Welding processwhich occurs in closed plastic ring is not visible, whether in the welding process orafter the welding process the nugget is not visible, overlapping of the role ofmetallurgy, heat transfer and power, and the instantaneous nature of the weldingprocess etc. The quality of resistance spot welding has a direct relationship with thewelding process parameters, such as the welding current, welding time, electrodeforce and electrode shape, size. Among them, the welding current on the weldingquality is the most significant intuitive. So, means of quality monitoring for resistancespot welding in this study is carried out by analyzing the information of the currentparameters. The current parameter information collection is difficult becauseresistance spot welding current is great and it is a transient (typically a few cycles to afew dozen cycles). It is vulnerable to all kinds of interference as well. To solve theseproblems, a reasonable choice of the USB-9201high-speed data acquisition card asdata acquisition aspects of the quality monitoring system for resistance spot weldingis selected. In this way, the amount of information collected within a limited time and maximize the reduction of the information characteristics of the current parameterscan be increased.Data processing theory as the theoretical basis, the median filter is selected as afilter to filter out interfering signals. At the same time,3/8Simpson quadratureformula is selected as the integral method of data processing. Calculating the slopecorrection method can be chosen as correction method of data processing. Point bypoint integral can be selected as a method to calculate the current effective value. Thesubroutines which were filtering, integration, correction, calculating the currenteffective value and welding time of data processing is designed with Visual C++6.0development environment.In order to detect the feasibility and accuracy of this system for the weldingquality monitoring, a ripe quality monitoring system for the resistance spot weldingwith the system to monitor the current signal has been adopted in the same resistancespot welding process at the same time. Data can be displayed on the same monitor,data sampling time is one-to-one correspondence with each set of sampling data. Thecurrent signal data collected by this system has been considered a standard to test thereliability of this study on quality monitoring system for resistance spot welding.Monitoring and analysis of current parameters in resistance spot welding shows thatthe quality monitoring system for resistance spot welding is completely reliable, withan average accuracy up to99%, and monitoring accuracy can be improved as thesampling frequency increasing.