激光弯曲成形是利用激光束的能量修整板材曲率的一种新型柔性无模成形加工方法。为探索激光弯曲三维成形的机制以及成形过程中的物理现象, 对1Cr18Ni9Ti正方形薄板采用交叉线扫描策略激光弯曲三维成形制备了球冠面, 利用显式动态有限元方法分析了正方形薄板在激光扫描过程中的温度、应力、应变、节点加速度与速度以及形变的变化情况, 在二维激光成形温度梯度机制基础上探讨了激光弯曲三维成形中存在的物理现象。在扫描过程中, 薄板整体的温度随着激光扫描逐渐增加, 在任意时刻任意位置的加热都会造成整体薄板应力作用方向和大小的改变, 应力变化是形成圆周线的趋势, 由于扫描路径时空的变化导致正方形薄板四角的变形量有所不同。

Laser forming is a technique of using the energy from a laser beam to modify and adjust the curvature of sheet metals or hard materials. In order to explore the mechanism and physical process of three-dimensional (3D) laser forming of square sheet, spider scanning path was used to transform the thin square 1Cr18Ni9Ti sheet to the spherical dome by 3D laser forming. And dynamic analysis on 3D laser forming was studied. On the base of temperature gradient mechanism of two-dimensional (2D) laser forming, depending on the geometry and the thermo-physical properties of stainless steel 1Cr18Ni9Ti, the mechanism for 3D laser forming of thin square sheet to the spherical dome was developed. This paper discusses the interaction between the moving laser beam and the sheet, the temperature field on the sheet, and the step transition of strain, stress, acceleration, velocity and deformation of the nodes in laser forming. The temperature of the whole sheet is increasing during laser scanning. The heat at any time or position can cause the change of stress which shapes the circles line. But the deformation of the four corners are different from the scanning difference.