At present, new electrical control technologies have been widely used in domestic sheet-fed lithographic printing machines, such as PLCs, touch screens, and frequency converters. These new sheet-fed lithographic printing presses have the advantages of high reliability, energy-saving efficiency, and perfect functions compared with the old-fashioned devices of some years ago. In many current printing companies, the old type sheet-fed lithographic printing machines still have There is a considerable amount. If they are remodeled, all PLCs and touch screens are used, and a large number of lines need to be changed, which is almost equivalent to recreating the electrical control system. If only the main drive part of a sheet-fed lithographic printing press is used to reform the inverter, there will be less line changes and less work. It not only retains the simple and practical features of the original relay contact control, but also gives full play to the advantages of reliable and energy-saving inverter, and the cost-effectiveness of the transformation is high. In the following, we will discuss some applications of frequency converters in the transformation of domestic single-color and single-sheet lithographic printing presses.
1. Process characteristics of the press operation control
To make the inverter-driven variable-frequency motor well applied to the printing press and to meet the requirements of the production process, it is first necessary to understand the process characteristics of the printing press operation control, what kind of requirements it imposes on the function of the inverter, and then what type of model is selected Inverter, and how to specifically modify the original line of docking.
The operation of the sheet-fed lithographic printing press is driven by the motor through a belt drive, a gear drive, and a chain drive, and the rollers, the teeth row, and the mechanism are coordinated by the mechanical connection, so the motor of the main drive is controlled. Control the running status of the whole machine. In the mechanical adjustment, inspection, installation and removal of PS plates and blankets, cleaning the machine, you need to manually control the machine forward and backward mode of operation, about 4r/min speed is more appropriate. During the pause of printing, in order to ensure that the PS plate is not damaged, the ink is not dry, and the machine is to be run at the same speed for a long time. When the machine starts formal printing production, there is an initial speed of about 3,000 rpm. When the paper feeder starts to feed paper, it can speed up, making the machine produce at a higher speed, generally 6,000 to 8,000 rpm. In order to adapt to different production speed requirements, a high speed potentiometer can be used to adjust the high speed, and the actual speed value can be indicated by the speed meter. From the high speed of printing to the initial printing speed, there are two cases. First, the manual button decelerates, and the other is the detection of paper failure during the printing process, such as arrogance, no paper, double sheets, etc., so that the printing press is automatically decelerated and the various parts make coordinated actions accordingly, such as pressure separation and water stoppage. , from the ink, stop the paper and so on. At the end of production, press the stop button and the machine will stop smoothly in freewheel mode. In addition, in order to ensure personal safety, a safety switch or emergency stop button is installed at the dangerous part of the printing press. As long as these switches act, the machine should be stopped immediately regardless of the state of the machine, and the whole machine should be braked.
2. Requirements for the function of the inverter
(1) There must be three speed control and direction control functions to meet the requirements of positive and negative point vehicles, positive low speed, initial printing speed, and high speed; the speed of the machine must be instructed so that the operator can clearly determine the current operating status; The deceleration process should be steady, and the speed should be appropriate. When the speed is changed, it can be smooth and shock-free in time. When the inverter itself has a fault, it must also stop the whole machine.
3. Inverter parameter selection
According to these requirements, the vast majority of inverters can meet, and for the occasions used, select the universal inverter. The voltage capacity is selected according to the power supply used and the motor used in the original machine. 400V class is used here, 5.5kW single-color machine, 11kW inverter used in two-color machine, there are a wide variety of inverters on the market, generally choose the mainstream products with good quality, such as Mitsubishi A540 series, Yaskawa G5, Delta, etc. Although the price of the product is higher, the quality is guaranteed.
1. Process characteristics of the press operation control
To make the inverter-driven variable-frequency motor well applied to the printing press and to meet the requirements of the production process, it is first necessary to understand the process characteristics of the printing press operation control, what kind of requirements it imposes on the function of the inverter, and then what type of model is selected Inverter, and how to specifically modify the original line of docking.
The operation of the sheet-fed lithographic printing press is driven by the motor through a belt drive, a gear drive, and a chain drive, and the rollers, the teeth row, and the mechanism are coordinated by the mechanical connection, so the motor of the main drive is controlled. Control the running status of the whole machine. In the mechanical adjustment, inspection, installation and removal of PS plates and blankets, cleaning the machine, you need to manually control the machine forward and backward mode of operation, about 4r/min speed is more appropriate. During the pause of printing, in order to ensure that the PS plate is not damaged, the ink is not dry, and the machine is to be run at the same speed for a long time. When the machine starts formal printing production, there is an initial speed of about 3,000 rpm. When the paper feeder starts to feed paper, it can speed up, making the machine produce at a higher speed, generally 6,000 to 8,000 rpm. In order to adapt to different production speed requirements, a high speed potentiometer can be used to adjust the high speed, and the actual speed value can be indicated by the speed meter. From the high speed of printing to the initial printing speed, there are two cases. First, the manual button decelerates, and the other is the detection of paper failure during the printing process, such as arrogance, no paper, double sheets, etc., so that the printing press is automatically decelerated and the various parts make coordinated actions accordingly, such as pressure separation and water stoppage. , from the ink, stop the paper and so on. At the end of production, press the stop button and the machine will stop smoothly in freewheel mode. In addition, in order to ensure personal safety, a safety switch or emergency stop button is installed at the dangerous part of the printing press. As long as these switches act, the machine should be stopped immediately regardless of the state of the machine, and the whole machine should be braked.
2. Requirements for the function of the inverter
(1) There must be three speed control and direction control functions to meet the requirements of positive and negative point vehicles, positive low speed, initial printing speed, and high speed; the speed of the machine must be instructed so that the operator can clearly determine the current operating status; The deceleration process should be steady, and the speed should be appropriate. When the speed is changed, it can be smooth and shock-free in time. When the inverter itself has a fault, it must also stop the whole machine.
3. Inverter parameter selection
According to these requirements, the vast majority of inverters can meet, and for the occasions used, select the universal inverter. The voltage capacity is selected according to the power supply used and the motor used in the original machine. 400V class is used here, 5.5kW single-color machine, 11kW inverter used in two-color machine, there are a wide variety of inverters on the market, generally choose the mainstream products with good quality, such as Mitsubishi A540 series, Yaskawa G5, Delta, etc. Although the price of the product is higher, the quality is guaranteed.
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