Functional requirements for the inverter of the ho

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At present, the new technology of electrical control has been widely used in domestic sheet fed lithographic printing machines, such as PLC, touch screen, frequency converter and so on. Compared with the old type of equipment a few years ago, these new sheet fed lithographic printing machines have the advantages of high reliability, energy saving and high efficiency, and perfect functions. However, in many printing enterprises at present, the old type of sheet fed lithographic printing machines still have a considerable number. If they are transformed and PLC and touch screen are all used, a large number of lines need to be changed, which is almost equivalent to remaking the electrical control system. If only the main drive part of the sheet fed lithography press is transformed with frequency converter, the line change is small and the workload is small. It not only retains the simple and practical characteristics of the original relay contact control, but also gives full play to the advantages of the frequency converter in reliability and energy saving, and the cost performance of the transformation is high. The following is about the application of frequency converter in the transformation of domestic single and double color sheet fed lithography press

1. Process characteristics of printing machine operation control

in order to make the development of frequency converter driven testing machine, the frequency conversion motor can be well applied to the printing machine and meet the requirements of production process, we must first understand the process characteristics of printing machine operation control, what requirements it puts forward for the function of the frequency converter, and then choose what kind of frequency converter with high elasticity and no hair number in vacuum, and how to concretely transform and connect the original circuit

the operation of the sheet fed lithographic press is driven by the motor through belt drive, gear drive and chain drive. The action of each drum, tooth row and mechanism is coordinated by mechanical connection. Therefore, the motor that controls the main drive controls the piston to rise by a certain distance to achieve the operation state of the whole machine. During mechanical adjustment, inspection, installation and disassembly of PS version and blanket, and cleaning of the machine, it is necessary to control the forward and reverse operation of the machine by manual car counting. The speed of about 4r/min is more appropriate. During the printing pause, in order to ensure that the PS version is not damaged and the ink is not dry, the machine should be operated at the same speed for a long time. When the machine starts formal printing production, it has an initial speed of about 3000 rpm. When the paper feeder starts to feed paper, it can accelerate to make the machine produce at a higher speed, generally 6000 ~ 8000 rpm. In order to adapt to different production speed requirements, the high speed can be adjusted through a speed regulating potentiometer, and the actual value of the speed can be indicated by the speedometer. There are two situations when the printing speed drops from the high speed of printing to the initial printing speed. One is to slow down the manual button, the other is to detect paper faults in the printing process, such as skew sheet, no paper, double sheet, etc., which makes the printing machine automatically slow down, and all parts make coordinated actions accordingly, such as pressure off, water off, ink off, paper feeding stop, etc. At the end of production, press the stop button, and the machine will stop smoothly in a free stop mode accordingly. In addition, in order to ensure personal safety, safety protection switches or emergency stop buttons are installed in the dangerous parts of the printing machine. As long as these switches act, the machine must stop immediately and the whole machine must be braked urgently no matter what state it is in

2. Requirements for the functions of the frequency converter

(1) there should be three-stage speed control and direction control functions to meet the requirements of positive and negative counting, positive and low speed, initial printing speed and high speed

(2) the speed value of high-speed operation is variable, and it is best to adjust stepless speed through manual potentiometer to meet different process requirements

(3) there should be speed indication for machine operation, so that the operator can know the current operation state

(4) the acceleration and deceleration process of the machine should be stable and the speed should be appropriate, so that the speed change is timely and smooth without impact, and the whole machine should also be stopped in case of failure of the frequency converter itself

3. Parameter selection of frequency converter

according to these requirements, the vast majority of frequency converters can meet. For the occasions used, choose general-purpose frequency converters. The selection of voltage capacity depends on the connected power supply and the motor used by the original machine. Here, 400V grade, 5.5kW frequency converter for monochrome machine and 11kw frequency converter for two-color machine are used. There are a wide variety of heart frequency converters as the main engine in the market. Generally, mainstream products with good quality are selected, such as Mitsubishi A540 series, Yaskawa G5, Delta, etc. Although these products have high prices, their quality is guaranteed

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