40Cr圆棒低应力剪切的激光旋切 环形槽理论与试验研究
Theoretical and Experimental Study on Laser Rotary Grooving for 40Cr Bar Low-Stress Shearing

针对传统剪切工艺存在的断面质量差、精度低等问题,提出了一种用于金属圆棒低应力剪切的激光旋切环形槽方法,并以40Cr圆棒为例,建立了40Cr圆棒激光旋切环形槽的数学模型;利用L25(56)正交试验对激光器参数(峰值功率Pk、脉宽τ、脉冲频率f)和加工参数(加工转速n、离焦量s、重复圈数N)等影响因素进行了研究,通过方差及槽型分析得到了各影响因素的主次关系及最优工艺参数范围,并对采用最优工艺参数旋切环形槽的40Cr棒料进行了剪切试验。研究结果表明:影响40Cr圆棒激光旋切环形槽深度h的各因素的主次顺序为N、s、Pk、f、τ、n,其中N和s的F值分别为11.925和5.268,大于F的临界值4.11,具有显著影响;最优工艺参数范围为峰值功率Pk≥9.6 kW,脉宽τ≥0.3 ms,重复圈数3≤N≤10,加工转速10 r/min≤n≤25 r/min,离焦量s=0 mm;40Cr圆棒激光旋切环形槽的理论深度和试验深度的误差平方和为0.112 mm2,表明理论槽深的计算公式误差小、准确度高;应用该技术的40Cr圆棒剪切断面平整,断面倾斜度仅为0？？3°,比传统剪切工艺的精度提高了12倍以上,剪切质量公差仅为0.35％,比传统剪切工艺的精度提高了6倍以上。
A laser rotary grooving method on metal bar for low？？stress shearing was developed to improve the precision of billets. A mathematical model was established through theoretical analysis on the laser rotary grooving process of 40Cr bars, and then L25(56) orthogonal tests were conducted to study the influence of factors including the laser parameters such as peak power (Pk), pulse width (τ) and pulse frequency (f), and the processing parameters such as processing speed (n), defocusing amount (s) and repeat turns (N). The influence order and optimum range of these factors were obtained by means of ANOVA analysis, and further shearing experiment was carried out on 40Cr bars. The results indicate that the influence order of the factors is N>s>Pk>f>τ>n, and the F values of N and s are 11.925 and 5.268 respectively, both of which have remarkable effects. The optimum ranges of these influencing factors are: Pk≥9.6 kW, τ≥0.3 ms, 3≤N≤10, 10 r/min≤n≤25 r/min, and s=0 mm. The sum of squares of errors (ε) between theoretical depth and real depth is 0.112 mm2 which proves that the calculation formula of theoretical groove depth h is accurate. Compared with the 40Cr billets processed by traditional shearing, the sheared surface inclination is 0.3°, and the weight tolerance is only 0.35％, resulting in an accuracy improvement of more than 13 times and 8 times, respectively