| The Dummy Block transportation is one of main auxiliary equipments of the 125MN Extrusion Press, undertaking the task of transporting Dummy Block, which mainly includes transportation, lean to vehicle and raise three processes. Before transformation, the control system of raising mechanism (transport car) mainly uses a relay-contactor device to control. Normally this elevator concatenates additional resistance on motor rotor circuit to switch on and modulate speed, and uses the simple hand-controlled electric switch to realize Dummy Block's lean and rise. This control system has such defects as poor reliability, low precision, complex operation, high failure rate, and in efficiency and so on. Therefore, research on the control system of The Dummy Block transportation has practical significance.This paper, considering the above-mentioned questions, applies PLC, variable frequency control technology and electro-hydraulic proportional valve control technology and Profibus-DP network technology to the system, and conducts a deep study on the feasibility.(1) Pads raise transport plane takes the current advanced frequency control program. The system utilizes vector control technology according the working environment. Just the control commands of positive rotation, reversion and multi-speed, and so on, to transducer make the elevator run at the set curve, achieving the steady work requirement. Design and select more power transmission motors and smaller drive ratio transmission equipment, in order to raise the pads transport speed.(2) In lifting mechanism, design and adopt Electro-hydraulic Proportional Directional Control Valve to replace the common valves, and install movement sensor to measure lifting height of the Dummy Block. The control system got feedback of the measured location information in order to control the Proportional Valve's working and improve control accuracy.(3) The system adopted Profibus-DP communication for its simple hardware connection and adopted PLC for control, software flexibility, convenient debugging, little maintenances and high reliability. A reduced intermediate links of relay-contactor control system, a decrease of hardware and control line, and a great improvement of system stability and reliability were the features of the communication mode.simultaneity,which ensure the centralized management and remote control.(4) According to operational features of the Dummy Block transportation, adoption of IPC (Industrial Personal Computer) and touch screen were to supervise the variable frequency control operational condition of the transportation and lifting height. Users would complete works of devices connection, control flow programming, parameters configuration, information statement, and results printing etc. in configuration environment.The operation indicated that, after modifying control system, function improvements in the Dummy Block transportation include speeding-up, promoted accuracy, reliability, convenience, as well as a dynamic display. |
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