基于复杂移动热源模拟的激光自熔覆试验研究

Experimental study on laser self-cladding based on simulation of complexmoving heat source

激光自熔覆是一种利用激光进行特定材料表面强化的工艺,在激光自熔覆系统中,获取移动热源的复杂轨迹点是至关重要的.工程应用中,工件表面的激光自熔覆往往涉及复杂的三维路径,复杂路径所产生的三维坐标点不能使用通常的二维函数来简单表达.本研究通过有限元模拟激光自熔覆工艺过程,先用建模软件根据实验试样建立自熔覆轨迹复杂的三维模型,导入到有限元软件中进行分析,然后针对工业生产中常用的汽车模具材料GGG70L(德标球墨铸铁)建立逼近真实的有限元模型,提出线性插值方法并运用在移动热源子程序中,实现了复杂三维自熔覆轨迹的模拟.采用激光光斑20 mm,激光扫描速率8 mm/s,激光功率2800 W,将有限元模拟形变量的实验与工程实验进行对比分析,结果表明两者的平均误差约为0.7%,误差范围在实际工程可接受的范围之内,说明有限元模型和模拟结果可靠,可在一定程度上代替工程实验,从而提高激光淬火实验的效率并节省成本.

Laser self-cladding is a process for surface strengthening of specific materials by laser.In the laser self-cladding system,it is very important to obtain the complex path points of the moving heat source.In the actual scenario,the laser self-cladding on the surface of the workpiece often involves complex three-dimensional paths,and the three-dimensional coordinate points generated by the complex paths cannot be simply expressed by the common two-dimensional function.In this paper,the process of laser self-cladding was simulated by finite element method(FEM).Firstly,a three-dimensional model with complex self-cladding paths was established according to the experimental sample by modeling software,and then it was imported into the finite element software for analysis.Secondly,a finite element model close to the real one was established for GGG70L(german standard ductile iron),which was a commonly used by automobile die material in industrial production.A linear interpolation method was proposed and used in the subroutine of moving heat source,and the simulation of complex three-dimensional self-cladding paths was implemented.The laser spot was 20 mm,the laser scanning rate was 8 mm/s,and the laser power was 2800 W.The results show that the average error is about 0.7%,which is within the acceptable range of the actual engineering,indicating that the finite element model and simulation results are reliable.It can replace the engineering experiment to a certain extent,thus improve the efficiency of laser quenching experiment and save the cost.