The Research On Sensors Array For Aluminum Alloy Spot Welding Quality Monitor System

Aluminum alloy spot welding has been widely used in auto and aerial production. But an effective way hasn't been found for on-line inspection of the nugget's quality. Until now, the present monitoring system for resistance spot welding quality mainly uses single sensor method to identify the spot welding quality, which identifies the quality according to the one-by-one relation of the characteristic number and the quality parameter in aluminum alloy spot welding. Nevertheless, the measuring method using single sensor is difficult to identify the quality of actual nugget due to the plentiful factors which affect the spot welding process in all directions. In order to overcome the flaw of single sensor measuring method and fully utilize the nugget information gained from sensor array in spot welding process, the aluminum spot welding monitoring system was constructed, in which magnetic sensors array is applied.In this paper, a monitoring system is being developed which used magnetic signal as the monitored object. The sensor system has three forms, which are both constructed with six magnetic sensors, that are called the linear magnetic sensors array,the annular magnetic sensors array and the magnetic sensors array. It is just the system that using magnetic signal as the monitor signal, and an arithmetic is being researched to extract the signal, which we called PCA method for magnetic sensors array developed in this paper. The three kinds of magnetic sensors array are used to the experiment which we changed the current parameter from 10kA, to 14 kA, and then 18kA when the array and the nuggent center's distance is 30mm, 60mm, 90mm.In the experiment, we have the aluminum alloy panels be welded five times and record the data. After the data are extracted, they are used to build relationships with integrating the nugget's information. Then we get the nugget's area, to identify the nugget's quality, from which we say that the monitoring system for resistance spot welding quality is developed.The system is able to acquire the characteristic signals, effectively reflect the change of welding spot nugget during the welding process, and satisfy the real-time measuring in spot welding process.