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Hydraulic Rolling Mill Electric Drive and Automation System（Drive&PLC）
1. Characteristics of electric drive system of hydraulic rolling mill
1.1 The drive control system used in all of Germany's SIEMENS 6RA80 full digital control device or AC frequency conversion device, which can realize four quadrant control, above base speed automatic weak magnetic speed, using the incremental pulse encoder as the speed detection devices, in order to improve the accuracy of speed control. In all digital control systems, the dynamic performance of the system is improved through current regulating loop controlled by adjusting angle. The shortest of the logical no circulation switching is 2-3ms. The pulse symmetry is good because of the formation and control of the digital trigger pulse. The full digital control also includes the EMF calculation and the magnetic field characteristic test, and the automatic optimization of the current loop and the speed loop can be realized. The system has more than 80 kinds of fault self diagnosis function. The parameters of the system are not affected by the change of temperature and time. Therefore, it has many advantages, such as convenient debugging, parameters suitable for quantification and preservation. Through the PROFIBUS-DP network communication with the first level automation system, the speed setting and the acquisition of the actual value of speed, voltage and current are realized on the network.
1.2 The system adopts SIEMENS full digital DC speed regulation or AC speed regulating device, so that all the indexes of the system have reached the advanced level of the same kind of rolling mill at home and abroad.
1.3 Using SIEMENS 6RA80 speed regulating device, the speed range can be more than 100 times. The device has automatic optimization function. By automatically optimizing the function, the main drive can achieve high speed control precision in the whole range. The precision of steady speed control is within ±0.1%.
1.4 By setting parameter, system running by setting the acceleration deceleration curve, and the acceleration of the system for real-time by point to point way to the uncoiler and coiler coiling, uncoiling, on the basis of dynamic compensation, which can follow the mill system, greatly reduced the deceleration when the belt may be dynamic rolling mill
1.5 The speed, current, magnetic field and friction torque are optimized to find the best regulator parameters to keep the rolling mill in good running state.
1.6 In the first few passes of rolling process, the rolling moment is larger, and the system is constant torque speed regulation. After several times, the torque decreases and the rolling speed increases. The system belongs to constant power speed regulation. So the electric drive adopts the non independent weak magnetic system with adjustable voltage and magnetic regulation. The motor is constant torque speed regulation below the base speed, and the speed is constant at the base speed.
1.7 In the weak magnetic and high speed running, the parameters of the motor change. In this change, the system also has the corresponding adaptive ability. The system is equipped with the magnetization curve to automatically generate the pre control function of the excitation current, which can ensure the speed of the magnetic field adjustment.
1.8 In the previous rolling process, the load torque fluctuates greatly because of the large blank thickness tolerance and the change of physical characteristics. In this regard, the system has strong anti-interference ability.
1.9 By setting the brake running curve and setting the corresponding current rising rate, the impact of the mechanical equipment can be effectively prevented and the life of the mechanical equipment can be extended.
1.10 In the high-speed operation, the deterioration of motor commutator commutation characteristics, through the current setting and speed related range, prevents motor speed when the fire ring, to ensure the reliable operation of the motor.
1.11 Between rolling mill drive and coiling drive, PLC automation device and upper management machine, the transmission of parameters and control instructions is realized by data communication.
1.12 The system has fast stopping function when it is broken down or other emergency faults to avoid damage to mechanical equipment.
2. Electric drive topology diagram of rolling mill
3. Automatic PLC system for rolling mill
Automatic rolling control adopts two level network control system, the transmission level uses SIEMENS 6RA80 full digital AC drive device or configuration, communication between boards, and basic automation level using the PROFIBUS-DP network data communication, basic automation level and upper level data communication through the MPI network, which can improve the control level of the whole system and can reduce the cable laying amount, to facilitate on-site maintenance. The process control is completed by SIEMENS S7-400PLC. The whole process control of rolling mill is realized.
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