Research On Control System For Stranded Wire Helical Spring Automatic NC Machine Tools

Stranded wire helical springs are cylindrical springs wound by stranded and multi-layered steel wires. Compared with ordinary helical springs, stranded wire helical springs have advantages of strength, fatigue life, damping, impact resistence, etc. With many structural parameters and complex process conditions, the processing requirements of stranded wire helical springs cannot be met by domestic existing machine tools. The accuracy of tension control and specified relieving twist ratio cannot be achieved. Under the principle of making springs with a spindle, a different diameter spindle is needed to meet a different diameter spring, and the processing length is limited by the length of the spindle. Besides, fixing the head of spring and shear needs to be done by hand. Consequently, to improve processing efficiency and accuracy, reduce costs, and develop high efficiency and accuracy machine tools has great significance. Based on the comprehensive analysis of the processing characteristics and existing problems, feasibility and implementation of stranded wire helical spring automatic NC machine tools control system was focused researched. The main research works in the dissertation are as follows:(1) The overall framework of control system is designed and completed in details under analysis of machine structure, working principle and system requirements. Architecture of control system is proposed by dividing control system into man-machine interaction system, servo drive control system, and tension control system.(2) The main hardware selection and circuit design of control system is completed under the control requirements of control system. Meanwhile, communication structure of each system is under research.(3) Man-machine interaction system including master interface, tension display interface which achieved ploting tension, and manual control interface is completed based on the study of function needs and mathematical model in machining process.(4) Control circuit and power supply circuit of servo drive control system is developed according to motor speed relationship. Besides, control program of PLC(Programmable Logic Controller) is developed with ladder programming to achieve seven-axis and two-cylinder linkage control.(5) The design of structure, circuit and program of tension control system is completed based on structural characteristics of the system. A compound control algorithm based on SVR(Support Vector Regression) with PID(Proportion Integration Differentiation) compensation is proposed to improve modeling accuracy and achieve real-time precise control of tension.