Application of Electromechanical Products on Automatic Pillow Packaging Machine

Pillow type packaging machine is a kind of packaging machine widely used in packaging industry such as food, medicine, etc. In daily life, a large number of daily products and food packaging are mostly packaged in a pillow type packaging machine. With the rapid development of China’s economy and the improvement of people’s living standards, it has brought good opportunities for development to the packaging machine industry, and the scope of application has become wider and wider. At the same time, higher requirements have been placed on the quality and production efficiency of packaging machines. .

The traditional pillow packing machine mainly adopts the structure of a differential gear box, and has the advantages of stable operation; the disadvantage is that the noise is large, the machinery is easily damaged, and the adjustment of the packaging accuracy is very troublesome. With the development of microelectronics, computer technology, and sensor technology, PLC technology has become more mature and its applications have become more extensive. The packaging machine host system adopts PLC as the core of the control system, which can make the packaging speed high, positioning accuracy, the system more reliable and stable, to meet the development requirements of the current packaging.

System composition

Pillow type packaging machine mainly completes the functions of forming, positioning, packaging and sealing. It mainly includes the following system parts:

Sealing and Cutting System: The sealing and cutting system of the pillow packing machine is composed of horizontal sealing knife (upper and lower) and vertical sealing knife (left and right). Its role is to horizontally and vertically package the packaging.

Heating system: The system needs to heat the horizontal sealing knife and the vertical sealing knife and control the temperature. The temperature meter is used to collect and control the temperature of the sealing knife.

Variable frequency speed control system: The inverter drives the cross cutter to achieve the purpose of sealing and cutting, and its speed determines the packing speed of the packaging machine. Vertical sealing feeding system: vertical sealing feeding system is composed of servo driven feeding roller and cross cutting feeding system. According to the technical indicators such as bag length of packaging film, it can accurately deliver the film, and can achieve accurate sealing (cross-cutting to the position of the packaging film color code ) Requirements.

Electric control system: The power supply adopts single-phase 220V/50Hz power supply. The host's electrical system is mainly composed of PLC, frequency converter, servo system, human-machine interface and so on. A proximity switch is installed on the transverse sealing cutter shaft, and the position is a crossing point; a photoelectric switch is mounted on the film feeding shaft and functions when a black cursor passes through the packaging film; a 360-line code is installed on the spindle of the longitudinal sealing and feeding system The controller measures the length of the bag (by PLC high-speed counting).

Electrical control principle system

The length of the bag is set by the corresponding facet on the man-machine interface (the distance between two cursors of the packaging film), and the bag length setting can also be achieved by starting the automatic length of the system bag length. When the automatic bag length measurement button is pressed, the servo system starts at a fixed speed and drives the vertical sealing system to feed. When the photoelectric switch detects the first cursor of the packaging film, the length is counted. When the next cursor arrives, the length is stopped and the calculated length of the sliver is displayed on the man-machine interface.

When the store button is pressed, the length is sent to the PLC as the length of the packaging film at the time of the current seal cut. The system adopts PLC communication mode to collect the command frequency F and output frequency H of the frequency converter. By calculating the average value of these two frequencies (to avoid the delay when acquiring a single output frequency), the current frequency of the frequency converter is used. By calculating the current running speed V of the motor, according to the transmission ratio of the mechanical structure, the current rotation speed R (rev/min) of the transverse knife can be calculated, which is used 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 and inverter to achieve the feeding and accurate packaging of the packaging machine.

Among them, PLC is the core of the whole system, carries on the signal, the data processing, its performance has determined the entire system quality. The system selects DVP-20EH. This model has three-way AB-phase high-speed counting (including two channels with single-phase bandwidth of 200K) and two high-speed pulse outputs (with a bandwidth of 200K), with powerful floating-point arithmetic functions and richness. Peripheral instruction set. The man-machine interface is used to input parameters and issue control commands. The system selected DOP-A57GSTD, which has 16 gray-scale display, high-speed hardware structure, can achieve online / offline simulation, presented to the user a really easy to use, programmable input interface.

The encoder is used to provide the position feedback signal and forms a closed-loop control system with the inverter, servo system and PLC. The realization of the function automatic cross-cut position alignment: by jogging (respectively for the cross-knife and longitudinal seal feeding point) the cross-cutting knife is just cut at the packaging film cursor position, and then presses the teaching mode start button, the servo system to The fixed speed starts and drives the vertical sealing system to feed. At the same time, the PLC starts to calculate the length. When it reaches the cursor position, the servo feeds the film to stop and sends the current meter length data to the current page of the man-machine interface. When the relative position storage is pressed, the PLC is packaged with the current relative position. Manual cross-cutting position alignment: In the manual operation, the relative position can be directly input on the man-machine interface. When running, the position of the cutter can be adjusted directly by moving the numerical input buttons left and right in the operation screen. Sealing and cutting tracking function: When the equipment is running, each time the cross cutter runs for one week, the tangential proximity switch is interrupted once through the PLC external, and the current encoder count value is collected and compared with the relative position stored in the PLC, according to the size of the difference. And positive and negative, to calculate the frequency of the command pulse issued by the PLC. Other functions: Through the panel or human-machine interface can start, stop, feed inching, cutter kinematic, machine inching and other functions, in the running, you can detect the current operating speed, record the number of processing, and can achieve clear zero.