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Application of AC Servo System in Heat Seal Cutting Bag Making Machine
Category: Heat Sealing Cutting
Date: 2018-01-09
Click: 886
Abstract: According to the current situation of domestic heat sealing and cutting bag making machine, Xinchuan Co., Ltd. has introduced a special servo control solution and successfully applied in the...

Abstract: According to the current situation of domestic heat sealing and cutting bag making machine, Xinchuan Co., Ltd. has introduced a special servo control solution and successfully applied in the domestic bag making machine equipment industry. The program adopts Xinchuan B series AC synchronous servo drive, 130 series AC permanent magnet synchronous servo motor , Touch screen, PLC, inverter, inverter motor and other major components;


I. Introduction

Shincheon Company introduced a dedicated servo control solution for the domestic situation of heat sealing and cutting bag making machine and successfully applied it in the domestic bag making machine equipment industry. The program adopted Xinchuan B series AC synchronous servo drive, 130 series AC permanent magnet synchronous servo motor, touch screen , PLC, inverter, inverter motor and other major components; according to the equipment process requirements selected high inertia 130 series servo motor as the main movement mechanism to ensure that the sealing bag making machine in the frequent start-up load under the stability of its own movement and Fast response, so that a servo motor feed speed to meet the cutting knife up and down the time required. At the same time, the mechanical mechanism is simplified, and the defects of low efficiency, low positioning accuracy, large energy consumption, low automation level and waste of materials of the original mechanical equipment are solved.

Second, the control principle

The entire equipment production process is divided into knives, positioning, sealing cut three parts. Heat sealing knife and cutter reciprocating up and down by the frequency inverter drive motor control, the long position of the servo drive servo drive control servo motor feed roller control, the other photoelectric sensor (also known as photoelectric eye), thermostat, proximity switch, do For the measurement and control components, responsible for determining the time and control signals issued to the implementation of the timing relationship between devices established. PLC as a carrier of the core program is responsible for sending pulse signals and various control signals conversion and transmission, and ultimately control the operation and coordination of the implementing agencies. Touch screen as a man-machine interface for parameter settings and monitoring of the entire machine health status, through the touch screen can adjust the bag length, reset, reset, jog and other operations; can also display the bag length value and the cumulative number of bags to be processed.

The picture below shows the control principle block diagram of heat sealing and cutting machine:

Third, the workflow

1. The system is powered on

Program initialization, enter the bag length value, adjust the temperature meter, seal knife temperature to seal the needs (sealing knife temperature, should be set according to the main motor speed level to plastic bag seal Department Nara prevail. If the sealing knife temperature is too high, it will cause the plastic bag seal to wear hot, therefore, it should be adjusted according to the main motor speed and the length of the sealing time); enter the manual adjustment mode , Check the mechanical parts, servo system, inverter, etc. can work properly, adjust the color photoelectric eye, it can sense the color scale changes.

Make a bag

Click the touch screen auto-run button, the main inverter motor (1.5KW) work, driven by the mechanical connecting rod seal cutter and cutter up and down reciprocating motion, the cutter every move up, the servo signal on once, sent by the PLC pulse control servo motor (1.5kw). The number of pulses determines the number of turns of the servo motor. The pulse frequency determines the speed of the servomotor. The servo motor drives the feed roller through the timing belt. The servomotor must be lowered to the bearing skin When the cutter and the sealing knife undercut, the plastic bag is formed. When the number of the cut bag reaches the preset number or the emergency stop button is pressed, the machine stops after the current plastic bag is produced, the cutter and the sealing knife Parked in high parking.

Bag machine generally has two kinds of sealing and cutting methods: blank bag fixed-length sealing and cutting and cutting, when the choice of blank bag fixed-length sealing and cutting color photoelectric eye does not work, PLC program according to the bag length, mechanical transmission ratio, servo drive Electronic gear ratio, the number of servo motor encoder and the perimeter of the feed roller to calculate the number of pulses required for positioning the servo system, and then driven by the servo drive servo motor feed roller rotation sent a certain length of the plastic bag, so as to achieve a white bag Fixed length sealing; When the choice of cutting seal, the process is as follows, the servo start signal is on, the servo motor in accordance with the PLC program pre-set motion curve for accelerated movement, constant speed movement, deceleration movement, low speed chase color, as shown in Figure 3 As shown, when the PLC receives the chasing signal, it immediately stops the servo motor through the interrupt mode. General chase color length of 10mm, and the pursuit of chase signal can only play a role in chasing the color range, other areas need to shield its interference signal. Chase color cutting debugging, the man-machine interface set the servo motor constant speed, first acceleration time, deceleration time set long, and then adjust the speed chase color, as much as possible to improve the speed chase color to chase color stable , Accurate to prevail. After adjusting the chase color speed, re-adjust the acceleration time, deceleration time, shorten the acceleration and deceleration time as much as possible to the plastic bag and the discharge roller does not occur relative sliding and chase color stable prevail. PLC program chase color sealing, the chase color signal count, three consecutive failed to detect, PLC stop the motor running, and drive alarm alarm. At the same time PLC program batch counting, when the batch reaches the early warning value, PLC drive alarm alarm.

Search speed curve



Fourth, servo system profile

This machine uses the servo system by the United States TI's latest digital signal processor DSP-driven. Adopting Mitsubishi industrial intelligent power module (IPM), IPM is higher than other servo products of the same type in China. It has the advantages of large capacity, strong anti-interference ability, large starting torque and fast dynamic response. It supports multiple communication methods, Standard full isolation RS485 communication module, RS422 / RS485 optional; inverter position control, speed control, torque control of these three control methods into one, and can control the dynamic switching mode, the use of more flexible and flexible; with Speed protection, overcurrent, overload, overheating, overvoltage, undervoltage, mains code error, communication error, abnormal PID feedback signal protection and abnormal display, the control process at a glance. The motor is a three-phase permanent magnet synchronous servo motor with three times the overload capacity, rated speed of 2500 rev / min, line encoder resolution of 2500.

Mechanical parameters:

Mechanical transmission reduction ratio of 1: 3

Cots diameter: 66 mm

Accuracy: bag length accuracy of less than 0.5mm, servo motor encoder pulse number 2500P / R, through the four frequency conversion, the resolution accuracy of 10000p / r, v servo = 360 ° / 10000 = 0.036 °, the motor output as feed The roll reduction ratio is 3: 1, the actual detection accuracy reaches: v roll = 360 ° / 10000 × 3 = 0.012 °, the corresponding bag length resolution precision is: vl roll = πD × (0.012 ° / 360 °) = 207.24 × 0.000033 = 0.006839mm

So their error is far less than 0.5mm, the real cause of positioning error is due to the servo motor start-stop is not smooth enough, when parking jitter, it is necessary to start and stop the servo motor speed control the appropriate speed loop, the position loop gain and Acceleration and deceleration time, the debugging process is as follows:

(A) Set the position loop gain to a lower value first and then gradually increase the speed loop gain to the maximum without generating abnormal noise and vibration.

(B) Slow down the speed loop gain and increase the position loop gain. With no overshoot in the entire response, there is no vibration with the position loop gain set to maximum.

(C) The speed loop integral time constant depends on the positioning time, and should be minimized if the mechanical system is free of vibration.

(D) Fine tune the position loop gain, speed loop gain and integral time constant to find the best value.

(E) Correctly adjust the first-order filter time constant of the position command.

Five, concluded

The heat sealing and cutting bag making machine is based on the traditional old equipment and is transformed from Xinchuan servo control system. It has the advantages of high efficiency, low energy consumption, high yield, good sealing precision, convenient and quick debugging, stable operation process and simplified Mechanical structure and other characteristics, with high technical content and better cost-effective for enterprises to create more benefits.

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