Research On The Plasma Of Laser Welding Based On Spectrum Information And Electric Signal

Laser welding, as a new welding technology, is becoming highly valued. Laser welding has many advantages such as high energy density, small heat affected zone, high welding speed. In the welding process, plasma will be generated with more laser energy. It has an important impact on the welding process and even determines the success of welding. Therefore, the study of laser welding plasma is of great significance. The research of plasma properties and internal mechanism contributed to a better understanding of the mechanism of laser welding and the improvement of laser welding process.The plasma diagnostics involve many methods, such as sound, light, electricity and spectral method. The spectral method and high-speed photograph are widely used, while the method of electric signal is seldom used. The domestic and international researches always adopt single detection method, research results are isolated. It requires a higher time resolution study that the laser welding plasma changes dramatically. There are few spectral investigations about wave phenomena of laser welding in real time.Therefore, this thesis firstly designs a new data synchronous acquisition about spectrum signal, electric signal and high-speed photograph. This acquisition could collect multi-dimensional information of laser welding plasma at the same time. The paper studies propagation law of matter and energy in laser welding plasma, through analyzing the characteristics of the parameters and wave characteristics of plasma.Results obtained from the study of multi-dimensional information are as follows: The optical and electrical synchronous acquisition system is able to obtain the whole feature information of plasma. The features of signals are characteristic and their changing rule is accorded with the variation law of plasma. The hybrid signals could fully characterize the variation of plasma.In the experiment of squarewave pulse laser, two forms of wave phenomenon are found. Multi-dimensional signals can explain the volatility of plasma, and are in accordance with relevant theory. In the laser welding with activating flux, the features of hybrid signals correspond with the mechanism of activating flux. The optical and electrical synchronous acquisition system could analysis the multi-dimensional information of laser welding plasma. It is practical with satisfactory results and provides a new way to research the laser welding deeply.