| With the combination of laser welding technology with automation technology and robot technology, the laser welding process has been widely used for autobody manufacturing, and has become the main assembly process of autobody parts, such as backplane, side, frame, roof, door and large covers and so on. On the other hand, laser welding technology has obvious advantages in welding of the automotive steel sheets as galvanized steel sheet, high-strength galvanized steel sheet and aluminum alloy, and increasingly replaced the resistance spot welding in body-in-white(BIW) assembly which open a new era of welding technology. Adopting laser welding technology has not only reduced the consumption of autobody's materials and weight, but also enhanced the strength, stiffness and safety of autobody. In this paper, the control system of production line of laser welding BIW was analyzed and designed, and the characteristic of laser welding with spot welding was compared.Firstly, according to the common characteristics of laser welding technology and autobody lap-welding process, the unit design method of the whole control system has been proposed. The basic control principle were that:with PLC as the control core and the industrial-computer as the assisted control core respectively; the touch screen implements monitoring and input operation, which is to communicate with the welding robot and optical fiber laser in time, and also monitors the welding fixture, gas roads, waterways and security doors. And then connect all the components mentioned above into the whole control system through the network communication technology and host computer system technology.Secondly, the control system of production line of laser welding BIW has been analyzed and designed. The main contents as shown below:analysis of overall control theory and function; design of control flow, electrical control principle, PLC control system hardware, PLC control system input circuit, PLC control system output circuit, PLC control system anti-jamming design, PLC control system programming, PLC control system program flow and production line network.Finally, this paper has made an example of welding the door by changing the weld parameters, and compared laser welding with resistance spot welding. The welding results showed that the flexibility, efficiency and quality of laser welding method were both higher than resistance spot welding. This provides a new welding production line technology for the development of miniaturization and lightweight, as well as improving comprehensive mechanical properties in atuobody structure. |
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