The Design Of The Dynamic Detection System For The Ball Screw’s Friction Torque

With the development of CNC machine tools to high speed and high precision, accuracy requirements of the ball screw have also increased. The friction torque is an important index to ball screw. In our country, the detection of friction torque is still in a relatively backward stage, small and medium-sized enterprises determine whether the friction torque is in accordance with the standard by workers feel mostly. So this thesis developed a set of ball screw friction torque dynamic detection system with the existing equipment in Nanjing ChangQing precision screw manufacturing Co., Ltd, it realizes the measuring process autoimmunization.In this paper, with the introduce of the transmission characteristics of ball screw, the generation mechanism of ball screw friction torque has been analyzed. Based on the pre-load mode of ball screw and Hertz contact theory, the effect of pre-load on the friction torque can be found. By using a simplified mechanical model of return system in ball screw, the influence of collisions between ball and return tube on friction torque has been analyzed. At last, these constitute the theoretical guidance part to the design and verification of the whole system.In the hardware part, based on requirements of the system, the overall design of the system has been done. Then this these introduced the design of the motion control system, servo system, data acquisition system, electrical control system. Through the selection of the motion control card, servo motor, data acquisition card, electrical components, semi closed loop motion control system, structure design of data acquisition system, and circuit design of power distribution system have been completed.In the software part, with the use of Visual Basic language, the software has a very good man-machine interface. According to the modular program design method, the software is divided into four modules:parameter input module, motor control module, data acquisition module, data playback/storage module.Through the use of dynamic link library of Motion control card and data acquisition card, the system realizes the automatic detection.Finally, in the actual detection part, axial velocity of the nut has been validated with the actual data, and by using the FFT Fourier transform to the actual data, the friction torque fluctuation has been analyzed. The actual data and calculation results are consistent with the theory, this verify the function and the stability of the detection system.