Analysis on the droplet transfer control of arc welding

It is important to get stable arc and droplet transferring in arc welding such as MIG and CO2 protecting welding because the stability of welding process have great influences on the weld bead formation and weld defect. However, researchers have different opinions on that. Some researchers believe that one pulse one droplet is the best, others think that one pulse multi-droplet can also provide satisfy weld. This paper systemically analyzes the reasons for that and provides an overview result of the transferring modes based on that. The result shows that both methods have its application fields and one pulse one droplet is more widely used in the world. Furthermore, different methods for testing and controlling of the droplet transfer mode are given in the paper Electrical signal, sound signal, light signal and spectral signal and magnetic signal are the most widely used methods. Based on the electrical signal and spectrum signal, the paper analyzes the theory of the methods and provides the advantages and disadvantages of the methods. In order to get enough information from the signal, all the study is based on mathematic methods such as fourier series and wavelet methods. It is found that the methods with spectral signal as the control base have promising future application fields. The spectral signal can give better signal quality with low noise rate than others and it can also provide abundant information of the welding process. All the process above can be verified by the synchronization high-speed video testing system. At last, the paper points out the future applications of the different methods in automatic producing line.