电主轴单元热误差半闭环主动控制方法

Semi Closed Loop Active Control Method for Thermal Error of Motorized Spindle Unit

作为影响数控机床精度稳定性的关键因素,电主轴末端热误差不仅由主轴轴承、电机生成热量引起,更与加工环境温度不稳定性密切相关。为在机床加工状态下并行抑制上述热干扰因素以保证主轴精度稳定性,构建了一种面向电主轴单元热误差的半闭环主动控制方法,该方法基于模糊神经网络-PID主动控制策略对电主轴单元内置循环液供液温度进行动态调整,以实现电主轴单元结构温度稳定性控制与热误差半闭环主动抑制。通过试验证明:该方法可以在22℃~18℃温度缓降工作环境中,将电主轴单元结构温升幅度控制在±0.5℃以内;并且相比于传统循环冷却控制方法,该方法可有效抑制各项主轴热误差(降低比例δx为57.1%,δy为56.9%,δz为34.7%),并放宽了电主轴单元精度稳定性维持对恒温加工环境的要求。

As a key factor affecting the accuracy stability of CNC machine tools,the thermal error at the end of motorized spindle is not only caused by heat generated at the spindle bearing and the motor,but also closely related to the instability of processing environment temperature.In order to suppress the above thermal interference factors in parallel and ensure the accuracy stability of the spindle,a semi closed-loop active control method for the thermal errors of the motorized spindle unit is constructed in this paper.The method adjusts dynamically the temperature of the circulating liquid in the motorized spindle unit based on the Fuzzy Neural Network-PID active control strategy,to realize the structure temperature stability control and thermal error semi closed loop active suppression of motorized spindle unit.The experimental results show that this method can control the temperature rise range of motorized spindle unit within±0.5℃in a working environment with 22~18℃variable temperature;and compared with the traditional circulating cooling control method,this method can effectively restrain the spindle thermal error(the reduction ratiosδx,δy,δz are 57.1%,56.9%,34.7%respectively),which can relax the requirement of constant temperature processing environment for accuracy stability of motorized spindle unit.