机械加工过程中刀具的切削颤振是影响加工质量和加工精度的关键因素。为了提高孔的加工质量,设计出一种新型抗振镗杆——约束阻尼型镗杆,该镗杆由镗刀头、基体层、阻尼层和约束层组成。针对约束阻尼型减振镗杆,首先从切削稳定性角度分析,增大镗杆的固有频率、静刚度及阻尼比,能有效提高镗杆的减振性能;其次利用ANSYS有限元分析软件得到各材料层厚度参数对镗杆减振性能的影响因子大小;随后对各参数进行优化分析获得优化的减振镗杆,优化减振镗杆的固有频率和阻尼比均大于普通镗杆,且相同激励下减小振幅可达34%;最后通过实际切削实验检验所设计镗杆的抗振性能,在相同切削条件及刀具悬伸长径比(L/D=6)下,优化减振镗杆所得到的表面粗糙度值较普通镗杆降低50%以上,由此说明约束阻尼型减振镗杆具有更好的抗振性能。
Cutting chatter is a key factor which influences the quality and accuracy in machining.In order to improve the machining quality of holes,a novel boring bar with constrained damping is designed and manufactured.It is made up of four modules,the cutting head,substrate layer,damping layer and constraining layer.First,the damping performance of the boring bar is effectively improved through increasing the natural frequency,static stiffness and damping ratio for cutting stability.Secondly,ANSYS is used to calculate the impact factor of the material substrate layer thicknesses for damping performance.The optimized damping boring bar is obtained by parameters optimization.The results show that both the natural frequency and the damping ratio for the damping boring bar are higher than those for a traditional boring bar.It is also shown that the amplitude of the optimized damping boring bar has decreased 34%than that of the traditional boring bar at the same exciting frequence.Finally,the damping performance of the designed boring bar is validated by practical cutting experiments.Experimental results show that the surface roughness of the damping boring bar is 50%lower than that of the traditional boring bar for the same cutting conditions and the same ratio of length to diameter(L/D=6).It demonstrates that the constrained damping boring bar has better anti vibration performance.