Research On Laser Bending Mechanism And Forming Process Plan For 3D Curved Plates

Forming parts account for much bigger proportion in the fields of the aerospace, shipbuilding, automobile and microelectronics. However, due to complex process, various products and low volume production and difficult to form materials like titanium alloy, nickel alloy, etc, the traditional whole heat forming needs a large number of high temperature resistant dies, which leads to a high expense and long times. In addition, some workpieces can not be processed because they are confined by the size of heating furnace. Laser forming is a flexible forming technology which forms sheet metal by means of laser-induced non-uniform thermal stress. As a forming method of hot accumulation, in comparison with conventional metal forming process, it requires no dies and external forces, especially, it is suitable for the hard and brittle materials forming and low volume production.In order to solve the associated problems in the process planning of complicated shape workpiece, the forming mechanism, the temperature and deformation rules, the method of forming accuracy control as well as process planning of complex shapes in the laser forming process are studied profoundly in the dissertation by experiment, numerical simulation and theoretical analysis. These investigations can provide theoretical basis for the rapid and precise forming of metal plate on the basis of the research of deformation behavior of plate under the different process parameters. The main research contents and original findings are as follows:(1) Research on forming mechanisms and the bending direction of plate. Firstly, the bending deformation and upsetting of plate under the temperature gradient mechanism, buckling mechanism and upsetting mechanism are analyzed. According to the strain field requirement of complicated shape forming, the temperature gradient mechanism and the upsetting mechanism are discussed further based on the strain distribution after laser forming, under which the plate produce the bending strain and plane strain, respectively. At the same time, a new mechanism, named as the coupling mechanism by the author is proposed, which is the combination of the temperature gradient mechanism and the upsetting mechanism. Moreover, it can be observed that the plate bends not only about the x-axis but also about the y-axis under the process conditions of the temperature gradient mechanism, the buckling mechanism and the coupling mechanism. To achieve the precise control of bending direction...