The control system of the hottest corrugated paper

The control system of the corrugated printing machine

the shaftless rotation corrugated printing control system uses PLC as the main control system. The printing plate roller, ink roller, paper feeding roller and electronic cam are all servo driven, the stepping motor adjusts the gap, the human-machine interface is monitored centrally, the field bus collects and transmits signals, and then combines with high-precision reducer, coupling, encoder, slide guide screw, synchronous belt and other mechanisms, Realize the speed synchronization and phase synchronization of each roller under high-speed operation. The vacuum adsorption electronic cam paper feeding mechanism ensures fast and accurate paper feeding. The phase adjustment function of the system makes the adjustment simple and easy. All these greatly improve the production speed, overprint accuracy and simplicity of operation

system composition

the system is composed of a paper feeding part and a four-color printing part. The paper feeding part mainly includes an electronic cam vacuum adsorption paper feeder. Therefore, the distance between the marking lines is also different from the structure and the paper feeding roller. The electronic cam vacuum adsorption paper feeding mechanism uses the negative pressure generated by the fan to tightly adsorb the paperboard on the paper feeding platform. Two electronic cam servo motors drive the paper feeding platform to move back and forth synchronously between the upper and lower positions of the paper feeding, and cooperate with the paper feeding roller and the paper feeding roller to complete the sequential transmission of the paperboard. On the basis of stable roller friction coefficient and paperboard pressure, the timing of paper feeding is related to the position and production speed of the one color printing plate. At a certain speed, when the one color printing plate turns to one position, the paper feeding starts, and when it turns to another position, the paper feeding stops, so as to ensure that the printing plate can accurately print the drawing on the corresponding position of the paperboard every time. For different sizes of paperboard, the timing of paper feeding/stopping also changes accordingly. The operator only needs to adjust the material number on the human-machine interface, and the system will automatically adjust it immediately to ensure the accuracy of the printing position. The action, speed and rotation angle of the two electronic cam Motors should be completely consistent, so as to ensure the continuous and stable operation of the motor and mechanism and the straight and straight delivery of the paperboard. Here, we use the two axis simultaneous linear compensation function to realize the real-time synchronization of the two axes. In addition, the cam motor also needs to meet the needs of long-term and frequent reciprocating forward and reverse operation. The system is required to select a servo system with high response, and adjust the servo parameters in combination with the load, give full play to the high-speed and high response characteristics of the servo system, and minimize the delay of transmission links and each link. At the same time, the system heating and recovery protection issues should be fully considered to make the motor work in a light load state (the schematic diagram of equipment and system composition is as follows)

after the cardboard is sent out, it enters the four-color printing section. The control of each color section is jointly completed by the printing plate roller, ink roller, paper supporting roller, paper pulling roller and air cylinder. Each roller is directly or indirectly driven by servo. At the same time, a stepper motor cooperates with the encoder to adjust the roller gap and position

the shaft diameter of the printing plate roller is usually large, the operation speed is very fast, and the printing overprint accuracy is required to be high, so the small speed difference between the printing plate rollers will cause overprint in a very short time. Let the speed difference between any two printing plate rollers in any period be △ V, and the system speed ring will adjust the speed difference within △ t time. Because the delay of the transmission mechanism is very small, set it to 0, then set the deviation generated by the speed difference △ V within △ t time as, and the formula can be summarized as follows:

= 0 △ t △ VDT

it can be seen that the smaller the speed difference △ V between loads, the faster the system response (i.e., the shorter △ T), the smaller the overprint deviation. This requires on the one hand to improve the mechanical accuracy, such as better installation concentricity, uniform load inertia, etc; In addition, when selecting the system, we should fully consider the matching with the load, and provide sufficient response capacity while providing sufficient load torque. At the same time, the debugging work is also very important. We should combine the load to make the system give full play to the optimal performance. In this regard, the automatic detection function of the servo system can be used to detect the load condition first, and then match the parameters according to the actual needs (such as improving the response or reducing the overshoot, etc.), and further fine tune until the conditions are met. At the same time, because each load and its transmission mechanism are different, the parameters of each servo will also be slightly different. The difference of mechanical transmission coefficient of load should be compensated electrically

the system uses the motion control function of PLC to control the servo system in real time, adopts a separate high-speed processor, and the operation is independent of CPU. Combined with the servo system, it meets the requirements of high precision and fast response. In addition, the encoder signal at the end of the load shaft is collected to detect and correct the running condition of the load, so as to eliminate the influence of transmission error and help analyze and find problems

the linear speed between the rollers should be consistent to avoid the slip of the cardboard. At the same time, the ink on the ink roller will be uniform and free of color patches. In addition, the action of the ink roller cylinder is also very important. When starting to feed paper, the cylinder drives the ink roller to fall in turn to ink the printing plate; When the paper feeding is stopped, the ink rollers are lifted in turn to avoid too deep inking of the printing plate. The timing of falling and lifting is determined by the position of the printing plate, so as to ensure the inking position and amount of the ink roller on the printing plate, so as to ensure the printing quality

because there are many specifications and models of paperboard, the printing process and control of paperboard with different specifications should be adjusted accordingly; At the same time, equipment cleaning, maintenance, plate hanging and other work are often carried out, which will inevitably cause human errors. It is necessary to adjust the phase of the printing plate roller from time to time. These are all realized in the program. The operator only needs to adjust the whole material number and correction value in the human-machine interface without making any changes to the equipment. The operation is simple, which greatly improves the work efficiency and flexibility

in addition, in the process of practice, we have summarized a set of simulation registration test methods to cooperate with the commissioning work. The servo feedback extruder is used as an important processing equipment and encoder signal through PLC detection. Through statistical analysis of it, the phase difference (pulse value) of each printing plate roller at any time can be calculated, and then converted into length (mm), the mechanical registration accuracy can be measured without inking and paperboard, which saves a lot of materials and shortens the debugging time

performance and characteristics

1. Due to the use of servo drive, its high-speed, high-precision and high response characteristics greatly improve the production speed. The maximum production speed of traditional equipment is usually 80 pieces/minute. This system can double the production speed of the equipment to 160 pieces/minute

2. the closed-loop design and rapid response ability of the system enable the equipment to maintain high control accuracy under high-speed production, with overprint deviation of 0 4mm (depending on the mechanical condition)

turn more than 80000 employees into more than 2000 self operated "small Haier" modes. 3. The electronic cam vacuum adsorption paper feeding mechanism changes the traditional push back paper feeding method, which will not cause the paperboard to bend or even fail to feed. It can also avoid the inaccurate positioning of the paperboard, so as to ensure the overprint accuracy. On this basis, it also greatly improves the paper feeding speed. In addition, the application of electronic cam makes the transformation production very simple without adjusting any equipment

4. the adaptive synchronization control of the system only needs to change the speed of the paper feeding roller or any printing plate roller, and the rest of the rollers automatically follow up to keep the line speed and phase synchronization all the time. The paper feeding frequency and the paper feeding/stopping time also change accordingly to ensure the overprint accuracy and position

5. The electronic cam and formula function make the transformation production very simple, without adjusting the mechanical mechanism, as long as the production part number is changed on the human-machine interface, it can be easily realized

6. before each operation of the equipment, the initial phase of the printing plate roller must be found. Traditional equipment usually uses a high-precision encoder to locate. This system can save this input, and simplify this work through the program. The operator only needs to operate according to the prompts on the human-machine interface. In addition, the initial phase offset caused by plate hanging or installation and maintenance can also be adjusted freely on the human-machine interface without shutdown or power failure

7. The application of fieldbus system saves a lot of tedious installation and wiring work and occupied space, ensures the stability, speed and accuracy of signal transmission, and enhances the maintainability of the system

conclusion

because the system has the above characteristics, especially its advantages of high efficiency, high precision and high flexibility, it has attracted the attention of many packaging and printing enterprises after being applied to the equipment. However, at present, only a few domestic companies adopt such technologies, and most of them are imported or joint venture technologies. There is no independent knowledge. There are two gripper property rights on the movable gripper seat. Its high price also discourages many enterprises, especially small and medium-sized enterprises. Therefore, we hope to promote the promotion of this technology in China and create better benefits for more enterprises