摘要
滚珠丝杠单元热特性仿真建模是精密机床直线进给系统热平衡优化设计与热误差抑制方法的基础.目前的建模方法中,对于滚珠螺母副的相对运动环节多采取不同程度的简化措施,这是造成现有模型仿真精确性欠佳的关键原因.本文在充分考虑丝杠螺母副相对移动效果的基础上,构建出一种精密滚珠丝杠单元瞬态热平衡-温升特性有限元仿真模型.首先,利用APDL定义了滚珠螺母与丝杠的位移-时间关系,从而在瞬态仿真建模中实现了滚珠螺母-丝杠结构的往复线性相对运动效果;其次,综合考虑了滚珠螺母-丝杠摩擦生热、滚珠-螺母与滚珠-丝杠间接触热阻及中空循环液-丝杠螺母副的流-固耦合换热效应等因素,构建起精密滚珠丝杠螺母副的热平衡-温升特性仿真模型;基于该模型重点研究了精密滚珠丝杠单元在不同循环换热条件下循环冷却液换热功率与丝杠螺母副生热功率的平衡匹配特性,及其对滚珠丝杠螺母副温升特性的影响.最终,通过对比试验验证了该仿真建模方法的准确性.研究结果表明:循环冷却液换热量不仅来源于螺母副生热,也来源于丝杠其他结构;只有当循环液换热功率增大至螺母副生热功率的1.5倍左右时,螺母副生热才可能被冷却液完全吸收,其温度值开始低于环境温度.该结论可以为滚珠丝杠单元的热平衡优化设计提供理论依据.
The simulation and modeling of the thermal characteristics of ball screw units form the basis of thermal balance optimization design and thermal error suppression for linear feed systems of precision machine tools. In current modeling methods,the relative motion of a ball-nut pair is simplified to various degrees,which is the key reason for the inaccuracy of the existing model simulation. In this study,a finite element simulation model of the transient thermal equilibrium-temperature rise characteristics of a precision ball screw unit was constructed based on the relative movement effect of the screw-nut pair. First,the displacement-time relation between the ball nut and screw was defined using the ANSYS parametric design language(APDL)to realize the reciprocating linear relative motion effect of the ball nut-screw structure in the transient simulation modeling. Second,the friction heat generation factors between ball nut and screw,contact heat resistance between ball nut and screw,and fluid-solid coupling heat transfer effect of hollow circulating liquid-screw nut pair were considered to construct a simulation model of the thermal balance temperature rise characteristics of a precision ball screw-nut pair. Based on this model,the balance matching characteristics between the heat transfer power of the recirculating coolant and heat generation power of a nut pair in a precision ball screw unit under different heat transfer conditions were studied. The influence of matching characteristics on temperature rise characteristics of a ball screw-nut pair was also studied. Finally,the accuracy of the simulation modeling method was verified via comparative experiments. Results show that the heat transfer of the circulating coolant not only results from the heat generated by the nut pair,but also from other structures of screw. Further,the generated heat of nut pair can be fully absorbed by the coolant only when the heat transfer power of circulating fluid increases to 1.5 times of the heat generation power of nuts,thereby decreasing the nut pair temperature below the ambient temperature. This study can provide a theoretical basis for the optimum design of thermal balance of a ball screw unit.
作者
商鹏
高长建
韩忠建
刘腾
高卫国
张建军
张大卫
Shang Peng;Gao Changjian;Han Zhongjian;Liu Teng;Gao Weiguo;Zhang Jianjun;Zhang Dawei(School of Mechanical Engineering,Hebei University of Technology,Tianjin 300130,China;Equipment Design and Manufacturing Technology Tianjin Key Laboratory,Tianjin University,Tianjin 300350,China)
出处
《天津大学学报（自然科学与工程技术版）》
EI
CSCD
北大核心
2019年第7期725-732,共8页
Journal of Tianjin University：Science and Technology
基金
国家自然科学基金资助项目(51775375)
天津市自然科学基金重点项目(18JCZDJC38700)
国家科技重大专项项目(2018ZX04031002)~~
关键词
滚珠丝杠
螺母副
接触热阻
流-固耦合
ball screw
nut pair
thermal contact resistance
fluid-solid coupling
