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The application of mechanical and electrical products in automatic pillow packaging machine

pillow packaging machine is a kind of packaging machine widely used in food, medicine and other packaging industries. A large number of daily necessities and food packaging used in daily life are mostly packaged by pillow packaging machine. With the rapid development of China's economy and the improvement of people's living standards, it has brought good development opportunities to the packaging machine industry, and the scope of application is becoming wider and wider. At the same time, it also puts forward higher requirements for the quality and production efficiency of packaging machines

the traditional pillow packing machine mainly adopts the structure of differential gear box, which has the advantage of stable operation; The disadvantage is that the noise is large, the machinery is easy to be damaged, and the adjustment of packaging accuracy is very troublesome. With the development of microelectronics technology, computer technology and sensor technology, PLC technology is becoming more and more mature and widely used. The main machine system of the packaging machine adopts PLC as the core of the control system, which can make the packaging speed high, the positioning accurate, the system more reliable and stable, and meet the development requirements of packaging now

system composition

pillow packaging machine mainly completes the functions of molding, positioning, packaging and sealing. It mainly includes the following system parts:

sealing and cutting system: the sealing and cutting system of pillow packaging machine is composed of horizontal sealing knife (upper and lower) and vertical sealing knife (left and right), which is used to seal the packaging horizontally and vertically

heating system: the system needs to heat the horizontal sealing knife and the vertical sealing knife, and control the temperature. The thermometer is used to collect and control the temperature of the sealing knife

frequency conversion speed regulation system: the frequency converter drives the cross cutter to achieve the purpose of sealing and cutting, and its speed determines the packaging speed of the packaging machine. Longitudinal sealing and feeding system: the longitudinal sealing and feeding system is coordinated by the servo driven feeding roller and the transverse feeding system for the next 1 or 2 months. According to the bag length and other technical indicators of the packaging film, it can accurately feed the film and meet the requirements of accurate sealing and cutting (transverse cutting to the color code position of the packaging film)

electrical control system: the power supply adopts single-phase 220V/50Hz power supply. The electrical system of the host is mainly composed of PLC, frequency converter, servo system, man-machine interface, etc. A proximity switch is installed on the horizontal sealing knife shaft, and the position is the transverse tangent point; Install a photoelectric switch on the film feeding shaft, which works when the black cursor passes on the packaging film; A 360 line encoder is installed on the spindle of the longitudinal sealing and feeding system to count the bag length (through PLC high-speed counting)

electrical control principle system

set the bag length (the distance between the two cursors of the packaging film) through the corresponding marking on the human-machine interface, and the bag length setting can also be achieved by starting the automatic side measurement of the bag length of the system. When pressing the automatic bag length measurement button, the servo system starts at a fixed speed to drive the longitudinal sealing system to feed. When the photoelectric switch detects the first cursor of the packaging film, it starts to count the length. When it runs to the next cursor, it stops counting the length, and the length calculated by spelling is displayed on the human-machine interface

when the storage button is pressed, the length is sent to the PLC as the length of the film for optimizing the production efficiency of the enterprise during the current sealing and cutting. The system adopts PLC communication mode to collect the command frequency f and output frequency h of the regulation No. 10/2011 on plastic materials and products in contact with food issued and implemented by the European Commission on March 24, 2014, and takes the average value of these two frequencies (so as to avoid the delay when collecting a single output frequency) as the current frequency of the frequency converter. The current running speed V of the motor is obtained through calculation. According to the transmission ratio of the mechanical structure, the current rotation speed r (R/min) of the Crosscutter can be calculated as the basis for the speed of film feeding

control system design

the control part of the system adopts PLC, and integrates man-machine interface, servo, frequency converter, etc. to realize the feeding and accurate packaging of the packaging machine

among them, PLC is the core of the whole system, which processes signals and data, and its performance determines the quality of the whole system. Dvp-20eh is selected as the system. This model has three channels of AB phase high-speed counting (two channels of single-phase bandwidth of 200K) and two channels of high-speed pulse output (bandwidth of 200K). It has powerful floating-point operation function and rich peripheral instruction set. The man-machine interface is used for parameter input and control command sending. The system adopts dop-a57gstd, which has 16 gray-scale display and high-speed hardware structure. It can realize/offline simulation and present users with a really easy-to-use and programmable input interface

encoder is used to provide feedback signal of position and form a closed-loop control system with frequency converter, servo system and PLC. Automatic cross cutting position alignment: by inching (inching the cross cutting knife and longitudinal sealing feeding respectively), cut the cross cutting knife exactly at the cursor position of the packaging film, then press the teaching mode start button, and the servo system starts at a fixed speed to drive the longitudinal sealing system to feed. At the same time, PLC starts to count the length. When it runs to the cursor position, the servo film feeding stops, and the current length data is sent to the current page of the human-machine interface. When the relative position storage is pressed, the PLC packs with the current relative position. Manual crosscutting position alignment: during manual operation, you can directly input the relative position on the human-machine interface of the test equipment that needs to be subversive; During operation, the cutter position can be directly adjusted through the left and right shift value input buttons in the operation screen. Sealing and cutting tracking function: when the equipment is running, the tangential point proximity switch will be interrupted once outside the PLC every week when the crosscutting knife runs, collect the current encoder count value, compare it with the relative position stored in the PLC, and calculate the frequency of the command pulse sent by the PLC according to the size and positive and negative of the difference. Other functions: start, stop, feeding inching, cutter inching, whole machine inching and other functions can be realized through the panel or human-machine interface. During operation, the current running speed can be detected, the processing quantity can be recorded, and zero clearing can be realized

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