精密镗床进给轴差异化主动冷却方法

A Differentiated Active Cooling Strategy for Feed Axis of Precision Boring Machine

针对精密镗床双驱丝杠进给轴连续运行时发热严重导致热误差较大的问题,提出了进给轴热源的差异化主动冷却方法。首先,确定了进给轴主要热源部位为轴承、电机和丝杠螺母副,分析了进给轴热源生热和散热机理,确定了关键边界条件,建立起主动冷却下的热流固耦合仿真模型;然后,设计了内置流道的冷却板并安装于热源处,每一冷却板分别设置冷却回路并通入4号主轴油作为冷却剂,每一冷却回路单独配置油箱进行独立调温;最后,建立了进给轴的轴承、电机及丝杠螺母等热源生热模型,精确匹配各热源生热率来控制冷却系统中进出口冷却液的温度,从而差异化地带走不同热源处所产生的热量以控制各部位温度,减小热误差。实验结果表明:与进给轴无冷却时对比,采用差异化主动冷却方法,最大热误差下降了58.56%以上;与恒温冷却方法相比,最大热误差下降了34.55%;同时缩短了热误差的稳定时间,表明该进给轴主动冷却方法能有效减小进给轴热误差。

A differentiated active cooling method for the heat source of the feed axis is proposed to solve the problem of serious heat generation during continuous operation of the double-drive screw feed axis of a precision boring machine,which results in a large thermal error.Firstly,the main heat source parts of the feed shaft are determined to be bearings,motors,and screw nut pairs.The heat generation and heat dissipation mechanisms of the feed shaft heat sources are analyzed.The key boundary conditions are determined,and a thermo-fluid-structure coupling simulation model under active cooling is established.Then,cooling plates with built-in runner are designed and installed at the heat sources,and each cooling plate is respectively provided with a cooling circuit and through the No.4 spindle oil as the coolant.Each cooling circuit is equipped with a separate oil tank for independent temperature adjustment.Finally,heat generation models of heat source for the bearing,motor and screw nut of the feed shaft are established to accurately match the heat generation rate of each heat source to control the temperature of the inlet and outlet coolant in the cooling system,so as to differentially take away the heat generated by the different heat sources to control the temperature of each part and reduce the thermal error.Experimental results show that when the differential active cooling method is used,the maximum thermal errors decrease by more than 58.56%and 34.55%,respectively,compared with the feed axis without cooling and the constant temperature cooling method.At the same time,the stabilization time of thermal error is shortened.These results indicate that the active cooling method of the feed axis can effectively reduce the thermal error of the feed axis.