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Time-varying reliability prediction modeling of positioning accuracy influenced by frictional heat of ball-screw systems for CNC machine tools
Precision Engineering ( IF 3.6 ) Pub Date : 2020-04-14 , DOI: 10.1016/j.precisioneng.2020.04.002
Tie-jun Li , Jia-hui Yuan , Yi-min Zhang , Chun-yu Zhao

Thermally induced elongation of a screw is the primary cause of deterioration in the positioning accuracy of half-closed-loop screw systems in machine tools. The failure mode of ball-screw feed-drive systems in relation to the positioning accuracy is defined as the response error of the carriage exceeding the axial tolerance. It is still challenging to accurately predict the thermal errors using conventional methods because the randomness of the influencing factors is not considered. This paper presents an improved random thermal network model subjected to dynamic thermal excitation for calculating real-time transient temperatures of ball-screw systems. Furthermore, a time-varying reliability model is proposed for estimating the gradual reliability of the thermally induced positioning accuracy of ball-screw systems with random thermal boundary parameters using the random thermal network. A ball-screw system of a computerized numerical controlled lathe is used as an example to show the practical application of the proposed model. Repeated experiments demonstrate the accuracy retaining ability and robustness of this method. This work provides the theoretical and practical method for real-time monitoring of the positioning accuracy reliability index for ball-screw systems and it has high accuracy considering the random parameters.



中文翻译:

数控机床滚珠丝杠系统摩擦热对定位精度的时变可靠性预测建模

螺钉的热诱导伸长是机床中半闭环螺钉系统的定位精度下降的主要原因。滚珠丝杠进给驱动系统相对于定位精度的故障模式定义为滑架的响应误差超过轴向公差。由于未考虑影响因素的随机性,因此使用常规方法准确预测热误差仍然具有挑战性。本文提出了一种经过动态热激励的改进的随机热网络模型,用于计算滚珠丝杠系统的实时瞬态温度。此外,提出了一个时变可靠性模型,利用随机热网络来估计具有随机热边界参数的滚珠丝杠系统的热诱导定位精度的逐步可靠性。以计算机数控车床的滚珠丝杠系统为例,说明该模型的实际应用。重复的实验证明了该方法的精度保持能力和鲁棒性。这项工作为实时监测滚珠丝杠系统的定位精度可靠性指标提供了理论和实用的方法,并且在考虑随机参数的情况下具有很高的精度。重复的实验证明了该方法的精度保持能力和鲁棒性。这项工作为实时监测滚珠丝杠系统的定位精度可靠性指标提供了理论和实用的方法,并且在考虑随机参数的情况下具有很高的精度。重复的实验证明了该方法的精度保持能力和鲁棒性。这项工作为实时监测滚珠丝杠系统的定位精度可靠性指标提供了理论和实用的方法,并且在考虑随机参数的情况下具有很高的精度。

更新日期:2020-04-14
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