激光熔化切割中切面上部条纹产生机理的分析

Analysis of the Formation Mechanism of the Upper Striation on the Cutting Surface During the Laser Fusion Cutting Process

条纹是切面上决定切割质量的主要结构,切口上部条纹的主要特征是:固液边界清晰,表面上几乎没有二次凝固相,厚度方向上近似垂直。文中提出了瞬时去除模型,并给出了具体的数学公式表示,通过变量替换将方程求解大幅简化,并采用差分法对其进行了数值求解。通过该模型分析了条纹形状随着Peclets数、熔融层厚度、激光功率等参数变化的规律。最后通过氧助激光切割碳钢实验对上述分析结果进行了验证。结果表明,条纹形状与文中的分析结果极为类似,二者随着切割速度的变化趋势的不一致主要来自氧化反应的影响和分析中参数单独变化的假设。

Striation is main structure on the cutting face which determines the resultant cut quality. The main characteristics of the upper striation are absent of re-solidified material, distinct solid-liquid interface and nearly perpendicular surface. One detailed mathematical model of the instantaneous remove model is given. With the appropriate variable transformation the simplified differential equations and boundary conditions is transformed to one which can be solved with the common finite difference method. Through this model the effects of Peclet number, melt thickness, laser power on the striation shape and linear size be given. Finally the present model is validated with the oxygen assisted laser cutting mild steel experiment. The similarity of the striation shape and real kerf can be observed from the results. The disagreement on the behavior under different cutting speed originates from the effect of oxidation and simplified parameter change assumptions in the analysis.