The frequency conversion control system in the wire drawing machine is currently the double frequency conversion system, one of which is used as the main drawing machine and the other is used for the take-up control; the small (fine) drawing machine currently has a single frequency conversion control system.
1 System configuration: The main pull is 37kW, and the take-up line is 11kW.
2 Process requirements:
(1) The highest take-up speed is 1200m/min;
The maximum operating frequency of the main drawing and take-up frequency converter can be calculated from the highest take-up speed required by the process. The main drive wheel diameter is 280mm, the initial diameter of the winding drum is 280mm, and the final diameter is 560mm. During the initial winding, the diameter of the reel is the smallest, and the speed requirement is the highest: 1200m/min, N0 = 1363r/min, so that the highest output frequency of the take-up frequency converter can be deduced as 45.4Hz. Therefore, the maximum frequency of the take-up frequency converter can be set to 50Hz to ensure that its maximum take-up speed is ≥1200m/min. The maximum frequency of the main drive inverter is calculated according to the transmission ratio to be 75Hz (the diameter of the winding drum is taken as the middle value of 420mm); the upper limit frequency is 45.4Hz (guaranteed the maximum is 1200m/min), and the debugging is basically set to 50Hz.
(2) Processing varieties: 2.8mm → 1.2mm, 2.5mm → 1.0mm, 2.0mm → 0.8mm.
(3) The tension swing rod is stable during the whole operation.
3 Control principle
In fact, the main drive inverter is only used for a simple speed regulation, which is used as a reference for the winding speed. The take-up frequency converter performs PID fine-tuning to control the operating frequency according to the signal feedback from the tension swing rod to ensure that the take-up speed is constant, and in a sense, it also ensures the constant tension of the take-up and take-up.
4 Debugging instructions and the advantages of non-inductive vector;
When debugging, firstly debug the open loop vector mode of the main pulling and rewinding inverter normally. Calculate the maximum operating frequency required by the winding inverter according to the maximum linear speed required by the process, and then correspond to the maximum frequency of the main pull according to the actual transmission ratio to ensure that the linear speed difference between the front and rear stages is not very large. Therefore, when PID adjustment is used to control the winding inverter according to the feedback value of the pendulum potentiometer, the linear speed synchronization of the front and rear stages can be well controlled. In addition, the acceleration and deceleration time of the main drive inverter is as long as possible (usually 40-60s), and the acceleration and deceleration can be carried out smoothly. The non-inductive vector inverter is used whether it is empty disk, full disk, or low speed, medium speed, or high speed. Ensure that the wire drawing machine starts smoothly, runs smoothly, and has a constant tension, realizing that the non-inductive vector inverter automatically detects the speed and diameter of the wire drawing. It completely replaces the traditional PLC and PID control mode.