Precise control of printing presses using Mitsubishi PLC

1 the introduction

In printing Precise PLC recent printing Precise PLC years, with the improvement of automation technology in China, factory automation also on a new step. Controller of PLC as an emerging industry, with its small volume, complete functions, low price, high reliability, has a unique advantage, won a wide application in all fields.

As the nation's largest printing machine manufacturer - northerners group company, in order to make our products stable performance, easy to maintain, we adopted PLC as the control scheme of the host controller. Due to the double color printing machine requirements is easy to operation, high accuracy, so its input and output points more, thus adopted double machine communication. Upper machine adopt mitsubishi FX2N - 80 - Mr 32 ex 4 d/A, mainly responsible for the control of main drive, each unit of the clutch pressure control, as well as the air pump, valve control, etc. A machine under the mitsubishi FX2N - 64 Mr 4 a/D, mainly responsible for the control of water roll motor, main drive speed output, adjustable version of motor data acquisition. Chose a mitsubishi 5.7 -inch touch screen, at the same time is mainly responsible for water roller, according to the motor speed adjustable version, and the machine fault display, etc. The system reliable operation, convenient maintenance, simple and intuitive operation, greatly improve the level of the offset press, is well received by users.

Among them, the upper machine and lower machine adopted RS485 communication, communication is convenient, and reliable. For multi-color machine, safety factor is very important. In the design, each unit should not only consider the safety control, including the standard unit of scram, security button; Consider convenient operation, each unit shall have excellent, including the button. Therefore, on the one hand, the input point increases a lot; On the other hand, walk line also is not very convenient. Adopts double machine communication, is a good way to solve this problem, the unit can get the line according to the principle nearby, the ark into closer to its control, saves walk the line, is also convenient for control.

Since the printing press is a high mechanical precision, the stand or fall of printed matter is on the one hand, the precision of machining and installation, on the other hand, also depends on the waterway, the balance of ink road, and the accuracy of the pressure. Each color group, two-color machine, there is water and ink device. In order to facilitate water roller speed regulating, each root water roll with a frequency converter control, at the same time, also need inverter to adjust the main motor speed. Therefore, in order to achieve the multi-channel speed regulation, we adopt mitsubishi 4 d/A d/A converter, it would give the digital quantity of PLC, according to the corresponding algorithm, converted into 0 ~ 10 v dc voltage output, well realize the multi-channel speed regulation requirements.

In the process of printing, the version is a more complicated process. Especially for multi-color machine, the accuracy of each version for can produce great influence to printing quality. If misregister, print will appear literally overlap or image is not clear. Generally speaking, the plate axial adjustment range is - 2 mm ~ 2 mm, weeks to adjust the range of 1 mm ~ 1 mm. If you are using a manual version, will waste a lot of time, and the accuracy is not high. In order to realize the automatic version, we installed in the version of the roll potentiometer, through the potentiometer to send 4 analog a/D, through PLC processing, version roller rotation accuracy can be well controlled within the scope of the play version.

Touch screen as a new man-machine interface, emerged from a concern, it's easy to use, powerful features and excellent stability makes it very suitable for the industrial environment. User can freely combination of text, button, graphics, digital, etc to handle or monitoring management information may change at any time. With the rapid development of machinery and equipment, the former interface needs to be operated by a skilled operator, unable to improve efficiency. But using a computer interface, can clear instructions and inform the operator of machine equipment's current situation, make the operation simple and vivid. Use the touch screen, still can make machine wiring standardization, simplification, at the same time also can reduce the I/O points required for the PLC control, reduce production cost, is also relatively increase additional value of the whole equipment. Mitsubishi touch screen and mitsubishi PLC has good generality and can on-line monitor and modify the program, don't have to be repeated plug interface of trouble.

 3 software design

3.1 paper design

Press the overall electrical design is more complex, is also very strict with time. In many parts of the machine is equipped with proximity switch, used to detect the different time points. In the process of printing, paper feed quality is an important part of affecting the quality of machine. So-called paper go good or bad, is no slanting, double the phenomenon such as zhang, if there were crooked, double Zhang Xianxiang, under the condition of high speed, paper will go bad, involved in the machine, to destroy the rubber, bring a lot of damage to the user

In the experiments, we found that the program compiled according to the above process, the low speed there is no problem, but after speed increased to 7000 r/h, can appear crooked Zhang Suo phenomenon. Investigate its reason, mainly because of baldheaded reaction time and the magnet action time lag. Procedure in the process of execution, the circular scanning mode, in order to let the electromagnet output in advance, in the design, I used the interrupt and input/output refresh command, mitsubishi programming instructions make the electromagnet output executed immediately, ahead of the action time of the electromagnet, even under the speed of 12000 r/h, also can be a very good lock the defective paper, solved a big problem to the paper.

3.2 clutch pressure design

Away from the pressure, or pressure in the printing has the very important role. The accuracy of the clutch pressure, has a direct impact on print quality. Pressure early, will be dirty embossing roller, bring a lot of inconvenience to the operating; From early, will make the last on a piece of paper to print is not a complete pattern, resulting in waste of paper.

Printing, the version of the rollers and rubber roller pressure, first the rubber roller and embossing roller pressure. In our machines, pressure all adopt pneumatic device, each cylinder has an action of time. Because the printing speed is more quick, between 3000 ~ 12000 r/h, according to user needs to choose a different speed. The action time of the cylinder is certain, however, gear turning Angle is certain, therefore, the machine speed is not at the same time, the pressure time is also different. In order to solve this problem, we according to the theoretical calculation values, find out the different machine speed, the delay time of the machine. USES the comparison order, when the machine speed and the theoretical value is equal, delay the corresponding time, make the embossing roller and rubber roller accurate pressure. After many experiments, away from the pressure, the pressure is no problem.

3.3 the man-machine interface design

In human-machine interface, designed the picture 7, including the overall graphics, fault, according to the machine speed and counter, water roller speed display, monitoring, etc. Fault display using indicator, to stand out components flashing effect can be realized, it is convenient for operator know failure parts, integral feeling is very good. In water roller speed display, designed a histogram, can display the water increase the size, just press the histogram, can add to the amount of water, but also easy to monitor

4       The conclusion

Press a set of electrical design belongs to the system design, including hardware, software design, has a wide scope. Here, I only introduce one of the more important parts, there are still many other detail, here no longer list. Use mitsubishi a set of control system, the feeling is reliable, convenient, in the process of machine batch production, found no big problem. Its PLC functional, reliable, durable, instruction is concise, compared with other products, feel mitsubishi whole software system interface is friendly, to the user programming, maintenance has brought great convenience. Its touch screen and PLC has good generality,] through the touch screen monitor and modify the program, it is not horse and other products. Anyhow, mitsubishi industrial control components for designers and users around the world has brought a lot of convenience.