Design and implementation of automatic positioning

Design and implementation of automatic positioning system of packaging machinery sealing and cutting machine

1 introduction

because the single chip microcomputer has very flexible control function and can provide reliable operation test, it has been widely used in the field of mechatronics. Using the function of single chip microcomputer to realize automatic control processing has become one of the most commonly used control methods in modern industry

the main goal of this design is to make full use of the resources and functions of the single chip microcomputer to complete the complex task of the positioning system of the sealing and cutting machine in the simplest way. When the system works, the photoelectric signal sensor is used to detect the motion parameters of the sealing and cutting machine and the software and hardware control function of the single chip microcomputer is used to realize the automatic positioning of the motion state of the sealing and cutting machine, so as to control the feeding speed of the stepping motor, make it cooperate with the sealing and cutting motion state controlled by the main motor, and realize the accurate sealing and cutting of the packaging bag; At the same time, it realizes the automatic electronic counting and display of packaging, the display and adjustment of bag length, inching and resetting and other operation functions

2 working principle of the automatic positioning system of the sealing and cutting machine

the application object of the automatic positioning system of the sealing and cutting machine is the packaging bag. Through the software and hardware functions of the 8751 single chip microcomputer and the signals detected by the photoelectric signal sensor, it realizes the automatic positioning of the movement state of the packaging bag conveying and sealing, controls the speed of the feeding stepping motor, and makes the feeding cooperate with the sealing and cutting action of the stepless speed regulation main motor, In order to realize the automation and accuracy of packaging bag sealing and cutting; At the same time, accurate production information is provided to the production operator through the display and alarm system

the working principle of the automatic positioning system of the sealing and cutting machine. The dotted line in the figure is 8751 single chip microcomputer and its external interface, with manual operation information and field information input at the input end; The output end has the display system and the actuator to respond to the operation results of the single chip microcomputer; Manual input includes: adjusting bag length, clearing, resetting, inching and other operations; The on-site information mainly includes optoelectronic eye information; The working status display shows the bag length value and the number of processed bags; The external actuator is a stepping motor that plays the role of bag feeding, and its frequency is controlled by a single chip microcomputer

in the packaging production industry, composite thin bags used as packaging bags can be divided into two types: one is blank bags, and the other is printed bags (color bags). The color bag is printed with a mark that can be recognized by the photoelectric signal detection sensor. The automatic positioning system of the sealing and cutting machine automatically detects the frequency of the sealing and cutting machine controlled by the main motor through the photoelectric signal sensor, which is converted into the number of pulses. Compared with the number of pulses detected by another photoelectric signal sensor, the frequency of the feeding stepping motor is adjusted to change its feeding speed and adapt it to the sealing and cutting movement of the main motor

the automatic positioning system can be divided into two positioning modes according to the different sealing and cutting bags: one is the blank bag positioning system, which is a fixed length positioning system, and only requires the speed of sealing and cutting movement to match the speed of bag feeding to meet the requirements of fixed length sealing and cutting; The other is the printing bag positioning system. The printing bag positioning system is the tracking of positioning, which requires that the position of each sealing and cutting must fall at the designated identification position

when we carry out various sealing and cutting tasks, we will inevitably encounter a problem; The bag length required by each task may change, which will inevitably affect the initial value of bag length preset in the system. Because the distance s between the photoelectric eye for detecting the color bag identification and the sealing incision is a fixed value, the bag length changes, which will inevitably affect the relationship between the bag feeding speed and the sealing and cutting speed. Therefore, in order to realize the automatic positioning of processing, a certain function adjustment must be made between the bag length and the distance s. However, this is only effective for sealing and cutting printed bags, but it is meaningless when sealing and cutting blank bags

3 hardware design of automatic positioning system

3.1 control of stepping motor

due to the limitation of hardware interface of 8751 single chip microcomputer and in order to improve the accuracy of system operation, the control of stepping motor adopts hardware distribution instead of software distribution. The operation, stop and movement speed of stepping motor are controlled by the P1.0 port output pulse frequency of 8751 single chip microcomputer. When changing the period of P1.0 port output pulse, the width of high and low levels of ABC three-phase winding will change. This leads to a change in the rate of power on and power off, thereby changing the speed of the stepper motor. To sum up, to control the motion state and running speed of the stepping motor, it is only necessary to adjust the pulse period and pulse number output by P1.0 port

3.2 application of photoelectric signal sensor

photoelectric signal sensor is a device that uses light as the medium for signal transmission. In the automatic positioning system of the sealing and cutting machine, two photoelectric signal sensors are installed (as shown in Figure 1). Its main function is to monitor the whole system in real time. When the photoelectric signal sensor receives the signal, it will transmit the received signal to the CPU in the form of level, and generate interrupt requirements: it requires the CPU to jump to the interrupt subroutine corresponding to the interrupt requirements in the next machine cycle after completing the current instruction, and execute the interrupt subroutine, Complete the real-time monitoring of the whole system and the calculation and transmission of relevant data

a photoelectric signal sensor (also known as photoelectric eye) is installed in front of the heat sealing device of the packaging machine. When the operation mode of the automatic positioning system of the sealing and cutting machine is the printing bag control, the photoelectric eye is turned on to detect the color signal on the printing bag and transmit the detected signal to the CPU. The CPU converts the signal into one of the pulse signals that can control the operation of the stepping motor through the software function

another photoelectric eye sensor is installed at the falling position of the sealing and cutting machine. When the automatic positioning system of the sealing and cutting machine is started, the photoelectric eye signal sensor detects the high or low level signals generated by the light changes caused by the lifting and falling of the sealing and cutting knife and transmits them to the CPU. The CPU realizes the automatic electronic counting function of the system and adjusts the feeding speed of the stepping motor through the counting software and pulse width measurement software

3.3 display system

the function of the display system in the automatic positioning system of the sealing and cutting machine has two aspects: one is to provide bag length information to the production operator; the other is to display the number of bags that have been sealed and cut, and combine it with the alarm system to realize the control of quantitative production

the hardware structure of the display system of the automatic positioning system of the sealing and cutting machine does not apply the decoder, which is realized by software; Display (2). Classification of fatigue test methods: the mode is serial port output common cathode dynamic display

3.4 alarm system

in the automatic positioning system of the sealing and cutting machine, the functions of the alarm system: first, when the number of sealing and cutting bags accumulates to 100 + 90 (n is any integer), the system will automatically alarm; When the number of sealed and cut bags accumulates to 100 (n is any integer), the system will automatically cancel the alarm. The realization of this function can help production operators realize quantitative production control. Second, when the action of the sealing and cutting machine detected by the photoelectric signal sensor is too fast, the system will automatically alarm. Its hardware structure is composed of buzzer, power amplification transistor and 8751 single chip microcomputer

3.5 reliability design of the system

in order to ensure the reliability of the automatic positioning system of the sealing and cutting machine and reduce the interference of the external interrupt signals input from INT0 and INT1 ports to the CPU operation, the system hardware usually refers to the maximum diameter and aperture ratio of the damage area as the damage factor, and the photoelectric isolation circuit is used in the design. When the photoelectric eye transmits the level pulse signal to the fracture in INT0 and INT1 of the CPU, it is input to the corresponding port of the 8751 single chip microcomputer through the optocoupler input and output isolation circuit and the six phase Schmidt trigger 40160, so that the operation of the internal data bus of the 8751 single chip microcomputer is not affected by the noise level

4 software design of automatic positioning system

4.1 definition of system

this system is an automatic positioning system that works continuously. Therefore, the feeding and sealing and cutting movements are continuous. Therefore, the system must be required to quickly reflect the requests of each interrupt. Multiple interrupt nesting constitutes the main body of the whole system

first, the sealing and cutting speed is obtained from the main motor, and the initial speed of the stepping motor is calculated through the speed conversion subroutine and sent to the stepping motor. Then the speed of the stepping motor is fed back to the single chip microcomputer, and then compared with the speed of the sealing and cutting machine, and the speed of the stepping motor is adjusted by the speed adjustment subroutine

in the automatic system of the sealing and cutting machine, the software mainly solves the problem of changing the fatigue testing machine, which is a common machine equipment. The problem is that the CPU converts the obtained bag length information and the pulse signal of the sealing and cutting speed of the main motor into the initial value of the timer to, and how to compare the difference between the two and then monitor the speed of the stepping motor in real time

the acquisition of bag length information is manually input by the operator during system initialization, and the system default value is 150mm. You can adjust the bag length by pressing the key to "1" or "1" the value. The output speed of stepping motor is determined by the pulse frequency of P1.0 port of 8751 single chip microcomputer. If it is detected that the number of pulses between the two sealing and cutting is longer than the bag sent during this period, the number of pulses corresponding to Jin min's wonderful report "vehicle materials solutions under the trend of light weight and environmental protection" for hundreds of automotive practitioners on the scene is less, which indicates that the feeding speed is slower than the sealing and cutting speed, and the feeding speed should be accelerated. At this time, the value of timer to increases; Conversely, reduce the value of to

4.2 design of system software flow chart

the main function of the system software is to judge the working mode of the automatic sealing and cutting positioning system (blank bag/printed bag) and realize automatic positioning operation

for the printing bag, due to the inevitable printing error, the bag length of the packaging bag is inconsistent. In order to correct the error information, we must use the second photoelectric eye to carry out real-time positioning of the printing bag, process the error through a series of software, and adjust the pulse series transmitted from the P1.0 port of the CPU to the stepper motor, so as to realize the accurate sealing and cutting of the packaging bag

when the processing object of the automatic positioning system of the sealing and cutting machine is a blank bag, convert the bag length set in the main program or manually modified into the number of pulses as the initial value for the comparison of the automatic positioning system; Compared with the number of pulses detected by the photoelectric eye 1, the comparison result is fed back to the CPU, which adjusts the frequency of the output pulse of the P1.0 port of the single chip microcomputer according to the feedback signal, so as to control the bag feeding speed of the stepping motor

reprinted from: Jiagong electromechanical