脉冲激光相变硬化中的二维点阵光强分布设计

激光强度空间分布是影响脉冲激光相变硬化效果的重要因素。现有的二维点阵光束按强度均匀分布设计,不能完全满足应用要求。为此提出基于有限元(FE)分析的光强空间分布逆向设计思路,并给出了实现方法。建立脉冲激光相变硬化有限元模型,考虑了材料热物性参数随温度的变化和相变过程,并用实验进行校核。研究了二维点阵分布参数对温度场的影响,从目标温度场和硬化层形貌出发对二维点阵的分布参数进行调整,获得优化的强度空间分布。针对汽车冲压模具表面强化的工艺要求,应用此方法设计出具有实用价值的激光强度空间分布。

Intensity Distribution Design of Two-Dimensional Spot-Array for Pulsed Laser Transformatoon Hardening

Spatial intensity distribution is a critical factor of pulsed laser transformation hardening.The existing two-dimensional spot-array designed as uniform density distribution cannot satisfy application requirements completely.A reverse method was proposed to design the intensity distribution based on finite element(FE)analysis.A FE model for simulating pulsed laser transformation hardening was established.In the model,temperature-dependent thermo-physical properties of material and transformation were taken into account.Temperature field and shape of predicted hardening calculated from the model was verified with experimental results.Research on relationship between distribution parameters and temperature field was carried out.With the validated FE model,the target temperature field or shape hardening layer was achieved by adjusting distribution parameters of the spot-array,and the optimal design of the intensity distribution was subsequently obtained.Aiming at surface hardening requirements of automobile's stamping die,the method had been applied to gain an intensity distribution design with application value.The results showed that the method was feasible and capable of providing bases for designing shaping lens and making the design more predictable.