高速电主轴热态性能及其影响

Thermal Properties of High Speed Motorized Spindle and Their Effects

高速电主轴作为高速机床的核心部件,其热稳定性影响着机床的加工精度。为有效预测并控制电主轴运转过程中的热态性能及其对主轴动态特性的影响,建立一种考虑系统热响应和预紧方式影响的角接触球轴承热-机耦合动力学模型,分析运行状态下主轴轴承的摩擦损耗及动态支承刚度,并应用电磁学理论讨论实际输入功率下内置电动机的电磁损耗;确定系统产热和热边界条件后,制定电主轴整体热-机动力学行为计算流程,对120MD60Y6型号电主轴展开温升试验,获取主轴关键部位温度变化规律。同时,理论计算和试验结果表明所建模型及分析流程具有足够的精度;轴承热位移对不同轴承配置的支承刚度和不同工况下系统的固有频率有着不同的影响;进行合理的轴承配置、选择合适润滑油量以及增加冷却水流量均可有效改善电主轴热态性能。

The thermal stability of high speed motorized spindles, which work as core components of high speed machine tools, plays an importants role in machining accuracy. To predict and control the thermal properties of motorized spindles under work condition and their effects on the dynamic characteristics effectively, a bearing thermo-mechanical dynamic model which takes preload methods and thermal responses into account is presented, and then friction loss and support stiffness of the bearing are analyzed. Meanwhile, the electromagnetic loss of built-in motor with actual input power is investigated with the use of electromagnetism. Based on the analyses of heat generation and heat convection boundary condition, a solution procedure is designed to analyze the comprehensive thermo-mechanical dynamic behaviors of the motorized spindle. An overall temperature rise test on a 120MD60Y6-type motorized spindle is carried out to acquire the temperature change law of the key parts. The good agreement between the theoretical results and the experimental data indicates that the proposed models are capable of accurately predicting thermo-mechanical properties of motorized spindles; the thermal displacement of bearing has different influences on support stiffness and natural frequency with various bearing configurations and work conditions respectively; the thermal properties of the system can be improved by selecting appropriate configuration, using proper lubricant oil flow and increasing cooling water flowrate.