摘要
高进给速度精车大螺距螺杆加工过程中,随着旋转螺纹件与刀具相对接触关系的实时变化、刀具磨损量的动态演变和工件材料去除导致的质量变化,加工系统的动力学特性呈现时变特性,研究其稳定性也就具有重要意义。首先结合精车削大螺距螺杆动力学模型,分别利用频域法和全离散时域法,提出一种适用于大螺距螺纹件的车削稳定域预估方法,并进行实验验证;然后在时域法基础上,考虑过程阻尼的影响,研究了不同刀具磨损情况对精车大螺距螺杆切削加工稳定性的影响,并验证测量结果与预测规律相吻合。研究结果表明:精车大螺距螺杆稳定性预测优先选用时域法;极限切深随后刀面磨损量增大而呈现出上升的趋势;选用转速分别为10r/min和25r/min,切深8mm,轴向进刀量0.05mm加工参数进行加工时,能获得基本符合工程实际要求的成品件。本文研究成果为高进给车削工艺参数优选奠定理论基础,同时丰富和发展以大螺距螺杆为代表的大型装备关键零部件的高进给加工理论并推进其工程应用。
In high-feed turning process,the dynamic characteristics of the machining system exhibit time-varying with real-time changes in the relative contact relationship between the rotating workpiece,the dynamic evolution of the tool wear and the cutting tool,and the quality change caused due to material removal.Combined with the dynamic model of large-pitch thread,using the zero-order frequency domain method and the improved full-discrete time-domain method,a cutting stability prediction method for turning large-pitch thread was proposed and experimentally verified.Based on the time-domain method,considering the influence of process damping,the influence of different tool wear conditions on the cutting stability of the large-pitch thread during finish turning process was investigated in this study,and consistency of the experimental measurements with the predicted results was verified.It is concluded that the ultimate cutting depth increases with the increase in tool wear;the machining parameters,such as the spindle speed is in the range 10-25 r/min,cutting depth is 8 mm,and axial feed amount is 0.05 mm,which should be given priority in the process planning of trapezoidal screw with large pitch.The results obtained provide the theoretical basis for the optimization of large-pitch thread turning process parameters.The enhancement and advancement of highspeed feed processing theory and high-efficiency machining technology is of great importance for the development of large equipment key components represented by large-pitch thread.
引文
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