Research On Real-time Monitoring System For Laser Welding Quality

Laser welding has been widely used in the electron,automobile,aeronautical manufacturing et al due to its advantages over conventional welding methods,such as high productivity,excellent weld quality and so on.As some random unstable factors may cause the weld statuses to fluctuate which may cause weld defects,so it can't meet the modern industrial demands for high quality.Therefore real-time monitoring of the laser welding becomes extremely necessary.The basic characteristics are the formation of the "key hole",the generation of melt pool and laser-included plasma during laser welding.These bring optical,acoustic and potential signals et al that can reflect the weld quality.The study for welding process monitoring abroad mainly focus on the acquisition of one or two signals from the above signals,which can't benefit to practical application very well. The research in this field of our country starts later,it's still in the theory stage.Visible light reflect the plasma status,infrared signals from the welding pool and the audible sound are selected, selecting proper arithmetic,using the powerful data treatment functions as to build a system of the quality estimating during laser welding.According to the characteristic during laser welding, analyse various kinds of physical phenomena. On the basis of predecessors' studies and demonstration,select acquisition three signals and multi-sensor information integration as the methods of in-process monitoring of the laser welding.The real-time monitoring contains two main portions,the hardware and the software.The hardware contains selection of transducer,the design of photoelectric conversion circuit,design a low noise amplifier(LNA) and high-order filters,set up the system of light acquirement, confirm the sensors' ficing. A multi-functional program based on Windows2000 is developed for signal acquisition and analysis with powerful exploit tool LabWindows/CVI software.Thus the high-speed acquisition and characteristic analysis for sampled signals come into reality. At last,carry out data collection on the basis of practical laser welding,and analyse the signals.Experiment results indicate that the system can provide correct data acquisition and can correctly reproduce the state transition of laser welding.