基于热传导方程的长脉冲激光打孔效能比分析

Analysis of energy efficiency ratio for long-pulse laser drilling based on the heat conduction equation

研究了脉宽为ms的长脉冲激光打孔的效能比,即打孔深度与激光能量之比。首先,测量了脉宽为1 ms、不同能量密度的长脉冲激光打孔深度,结果表明,激光打孔的效能比随着激光能量密度的增加而下降。根据长脉冲激光功率密度低、脉冲波形近似为矩形的特点,建立了稳态一维热传导模型,得到了打孔深度与Al板表面温度之间的关系。然后,将实验中测量得到的打孔深度作为边界条件,代入到上述关系式中,计算得到了不同能量密度下激光作用过程中的Al板表面温度,进而计算得到了气化损失率。计算结果表明,激光的能量密度越高,Al板的表面温度就越高,气化损失率就越大。最后,结合文献报道的实验结果,对相同能量密度、不同脉宽的长脉冲激光打孔深度的不同进行了讨论。所得到的结果均与文献报道结果吻合。

Energy efficiency ratio is studied for long pulse laser where the pulse width is millisecond order drilling. First of all, the different energy density long pulse laser drilling depths are measured. In the ex- periment, the pulse width of laser is 1 millisecond and then the energy efficiency ratio is obtained. The re- sults show that the energy efficiency ratio of the laser drilling decreases as the laser energy density in- creases. Due to long-pulse laser power density is low and the shape of pulse is approximately rectangu- lar,the one-dimensional steady-state heat conduction model is established, and the relationship between drilling depth and the surface temperature is obtained. Then, the drilling depth is measured in experiment as a boundary condition,and substituted into the above formula,and the surface temperature of the alu- minum plate and gasification loss rate are calculated during the laser irradiation. The results show that the higher the energy density of the laser, the higher the surface temperature of the aluminum plate and the greater the gasification loss rate. The obtained results are consistent with the reported ones in the lit- erature.