Design Of A Fault Test Bench And Its Measuring And Control System For Ball Screws

As common feed systems, ball screws are widely used in CNC machine tools, industrial robots and other equipment, which are one of the key components that influence the machining accuracy of CNC and motion accuracy of industrial robots. Therefore, it is necessary to monitor and identify condition of ball screws to ensure the normal operation of equipment. In this paper, a fault test bench and its measuring and control system (MCS) are designed to monitor the operating status of ball screws.First of all, combined with the size and operating parameters of ball screws, the overall conceptual design of a ball screw test bench is given. At same time, according to requirements of fault simulation and mechanism research for ball screws, the general scheme of MCS is designed to achieve the motion control of the test bench and vibration signals acquisition, including the architectures of hardware and software.Secondly, a dual motor synchronization control method based on fuzzy PID was designed and implemented. The synchronization control scheme of master-slave is confirmed. The fuzzy PID control algorithm is used to adjust the real-time synchronous speed of dual-motors. The fuzzy relationships among the three parameters of PID, error and error rate are analyzed, and the fuzzy rules are formulated to achieve fuzzy inference and tune the PID control parameters. The results of simulation and experimental analysis indicate that the proposed method can regulate the synchronization of dual motors effectively.Thirdly, the detailed design of hardware and software of MCS are given. The hardware is consisted of the DSP peripheral circuit module, the data acquisition module, the communication management module, the power management module, CPLD module and motor control module. The software of the MCS is divided into software of an upper computer and a lower computer. The serial port and Ethernet are used as the communication tools by the upper and lower computers, which achieve the transmission of motor control instructions and vibration signals.Finally, the test plans of the bench and MCS of ball screw are constructed, and MCS is developed. The testing results indicated that the developed MCS can implement the motion control of the bench and the acquisition of vibration signals. The feature extraction method based on AR model and power spectrum is researched, the analysis results show that the method can further extract the feature of vibration signals of ball screws. Meanwhile, the analysis results of localized defects of ball screw show that the system can meet fault simulation and test analysis of the ball screws.