Cooling effect and temperature regulation of oil cooling system for ball screw feed drive system of precision machine tool

In order to investigate the cooling effect of forced fluid circulation on the ball screw feed drive system of a precision boring machine tool, theoretical modeling of and experimental study on temperature control of screw shaft along with heat generation and dissipation interactions are focused in this paper. Thermal behavior measurements are conducted on the machine tool to detect the temperature of the feed drive system equipped with oil cooling circulation real-timely. Based on the heat generation and forced convention analysis of ball screw system, temperature distribution of screw shaft in the axial direction is modeled mathematically. Relationship between the heat convection coefficient and cooling system parameters is established to formulize the surface temperature distribution considering the flowing speed of cooling medium as time-invariant. Numerical simulation was conducted showing that the geometric dimension of flow passages and the speed of cooling flows significantly influences the thermal behavior. The fuzzy PID control strategy is employed to regulate the temperature of screw shaft with the flow rate of cooling fluid adjusted by a valve controlled hydraulic system. The relations between temperature rise and flow rate are formulated indirectly while taking the heat generation under the no-cooling working condition as disturbance. Measurements with feed drive system operating at different feed rates are preformed and the proposed temperature regulation method proves to reduce about 3 degrees C in temperature variation through experimental results based control system simulation.