Research On Positioning System Of Multi-spots Revolving Bending Press

Revolving bending press is an automated production equipment applied to mold the knee-piece, it inherits conventional processes of knee-piece-making which are "seven suppression of molding the knee-piece". According to the differences of power sources, the bending press in Fenjiu Daqu workshop divides into two types. One kind is motor driven chain transmission bending press, another kind is hydraulic motor driven bending press. The former determines the position of mold box with geneva mechanism. The latter determines the position with electrical open-loop control. Both adopt chain transmission. Because the chain transmission has a polygon effect, it is difficult to realize the accurate positioning and the noise is bigger. Regular adjustment of the chain tensioning device and more maintenance are required.Aiming at braking impact of chain transmission bending press making braking distance non-controllable and. the effects of load disturbance on positioning precision of mold box, revolving bending press is designed. The revolving bending press uses the rotation platform which is connected with mold box through rigid coupling to instead of the chain transmission. And the rotation platform is directly driven by the hydraulic rotation equipment. Meanwhile,the electro-hydraulic speed servo control system is proposed to reduce the braking impact and mechanical correction device is equipped to eliminate positioning accumulative error. The mathematical model of rotation platform is set up. According to the mathematical model, the control system block diagram is constructed. The rationality of the system is verified through the simulation analysis.The three-dimensional model of rotation platform mechanical system is established, its kinematics and dynamics simulation is carried out by the ADAMS software, and speed and the driven torque curve is obtained in order to determine the required flow rate and pressure in the hydraulic system. Comparation between the open-loop control hydraulic rotation platform and PID with torque compensation are made by the AMESim software. Finally, PID with torque compensation is selected to overcome positioning error brought by the load disturbance.Finally, a series of experiments on positioning system of the revolving bending press are given in this paper.The results show that the effects of load disturbance on positioning precision and brake impact is reduced,rotation platform positioning accuracy has improved significantly.