1. The composition of the transmission system of the paper cutter.
The drive of the paper cutter consists of an arc-shaped roller, a longitudinal cutter, a conveyor belt, a paper feeding roller and a cutter. The arc-shaped roller is mainly used to stretch the paper sheet and prevent wrinkling, so its speed is synchronized with or slightly faster than that of the paper industry; the longitudinal cutter generally needs to be about 1.2 times faster than the paper speed; the conveyor belt mainly drives the finished paper sheet to form a stack. Therefore, the four drive points control requirements are relatively low can be used frequency conversion drive open-loop control mode, and the main drive to form a speed chain type speed difference control, can meet the requirements.
Two. The basic control system structure of the paper cutter (as shown):
RS485 communication mode is used between PLC and frequency converter, AC servo control is used for paper feeding roller and paper cutter, and touch screen is used for operation control of paper cutter. The control between the feed roller and the cutter of the paper cutter is actually a high precision speed ratio control. We only need to control the cutting length within the error range. It's not like printing presses that require precise position control. Therefore, the high-precision position control mode is adopted for the control of the feeding roller and the paper cutter, and the high-speed pulse is output by the PLC as a given.
Three, servo control design the basic way of servo control.
It is mainly divided into speed mode, torque control and position control.
1. Speed mode: through the input of analog signal or the frequency of pulse, the rotational speed can be controlled, but it can not be directly controlled by positioning. The outer-loop PID control which needs an external position control device can also be positioned, but the position signal of the motor or the position signal of the direct load must be fed back to the upper-level for operation. It can also be widely used in speed regulation of transmission system. Since the control between the feeding roller and the cutter of the paper cutter is actually a high precision speed proportional control, the paper cutter control can also be used.
2. Torque control: Torque control is to set the output torque of the motor shaft through the input of external analog or the assignment of direct address. The set torque can be changed by changing the setting of analog instantly. This mode is mainly used in winding and unwinding which have strict requirements for material force. In the device.
3. Position control: Position control mode is generally through the external input pulse frequency to determine the size of the rotational speed, through the number of pulses to determine the rotation angle, but also some servos can be directly through communication speed and displacement assignment. Because the position mode can control the speed and position very strictly, it is generally used in the positioning device. Application areas such as CNC machine tools, printing machinery and so on.
Because the control between the feeding roller and the cutter of the paper cutter is in fact a high precision speed proportional control, position control is generally adopted, but the high precision speed control mode of position control is applied. In the control of the paper cutter, the position command is used as the given input for the AC servo system, and the digital frequency of the general servo unit is used. Given, you can use PLC to give or track encoder signals. The speed of the motor can be controlled by controlling the frequency of the given signal.