针对激光金属直接成形过程中的特征尺寸问题,采用ANSYS有限元分析软件,对方波作用模式下的激光熔池温度场进行了模拟分析。结果表明,在平均输出功率一定的情况下,熔池作用尺寸范围随着方波作用时间的减小而增大,而在光斑重叠率足够大的情况下,改变重复频率对熔池作用尺寸范围影响较小;在其它参数一定的情况下,熔池作用尺寸范围随着平均功率的降低而减小。结合模拟分析,设置相应的实验方案对方波作用下的各参数对金属直接成形特征尺寸进行了分析,实验结果变化规律与计算结果吻合。利用方波,成形出了具有小特征尺寸的薄壁零件。

Aiming at the problem of feature size in laser metal direct forming(LMDF) process,the temperature distribution of the molten pool caused by square wave laser is simulated by ANSYS software. The results show that under the condition of the same average power output,the function range of molten pool increased with the decreased of the duration of square wave,and the change of repetition frequency has little effect on the function range of molten pool when the laser beam overlap ration is big enough. The function range of molten pool is decreased with the decreased of average power output when other parameters are invariable. A corresponding experimental scheme is designed to analyze the influence of square wave parameters on the feature size of LDMF,and the numerical and experimental results agree with each other,a thin-walled part with small feature size can be formed with square wave laser.