Troubleshooting of vacuum pumping failure of the h

2022-08-11
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Troubleshooting of vacuum pumping failure of offset printing machine

the most common failure of offset printing machine is that the vacuum pump pumping is not strong, resulting in the PS plate and film, sulfuric acid paper carbon powder contact is not close and does not match when printing. There are many reasons for the formation. When encountering faults in this area, we should comprehensively analyze the causes of the faults and treat them differently, so as to eliminate the problem of insufficient vacuum pumping

1. There are two types of vacuum devices. First, the vacuum device of the plate printer includes a high-speed direct connected vacuum pump and a motor, that is, the motor and the vacuum pump share a rotor, and the speed of the motor is synchronized with the speed of the vacuum pump. Second, there is a device that separates the motor from the vacuum pump, and the energy of the motor is transferred to the vacuum pump by the V-belt. The offset press has been used for a long time, and the V-belt is damaged, relatively easy to slip, and the V-belt is elongated and deformed, which will affect the transmission of power. The decrease of the rotating speed of the vacuum pump per minute will 3. Click to rise to make the piston (workbench or upper beam) rise by 5 10mm, which will affect the size of the vacuum degree. The air extraction volume is small, the suction is not solid, and the print quality is poor during measurement

2. All gas circuits should be kept clean, and the inner wall of the pipeline should be free of dust, which can meet the experimental requirements required by customers, and the existence of fibers, sundries and foreign matters, so as to prevent blocking the gas circuit and affecting the extraction, so as to maintain the smoothness of the pipeline. In the process of vacuum pump pumping, the inner wall of the gas path is easy to be blocked by debris. During maintenance, it is necessary to take out the dirt with thin iron wire in time, so as to cultivate civilized production, cleanliness and hygiene as a good habit

3. The rubber cloth pad of offset printing machine and the rubber around the edge frame of elastic sealing rubber are aging, damaged and air leakage, resulting in inaccurate air extraction. The rubber cloth pad and elastic sealed rubber frame of the printing machine will have the disadvantages of aging, cracking and desulfurization when the rubber products encounter light, heat, acid and alkali, and chemicals. Any article also has a service life. In daily work, if the rubber cloth pad and elastic seal rubber frame are damaged and cracked, we can use rubber adhesive (to repair the rubber adhesive in the tires of cars and bicycles). First, grind the damaged rubber with a wooden file, remove the oil stain, and then apply a layer of rubber adhesive at the damaged grinding place. After compaction with heavy objects for a period of time and bonding firmly, It can be used for printing

4. The pipeline of the plate printer, especially the rubber pipe closest to the air outlet of the vacuum pump, is most likely to be sucked by the vacuum pump, causing the damage of the air pipeline. The effective way to prevent the rubber pipe from being sucked is to install several springs with the same diameter as the air pipeline in the rubber pipe. In this way, whether the rubber pipe is pumped by vacuum pump or the rubber pipe bends at the corner, it will not be sucked, deformed, damaged or leaked

5. The rotation direction of the vacuum pump motor should be the same as the direction of the arrow on the air pump. The wrong rotation direction of the motor is caused by the reverse phase of the three-phase power connection. As long as the line position is changed, the rotation direction can be changed. The rotation in the same direction as the arrow direction of the vacuum pump is air extraction, and the reverse direction is air blowing. Avoid the phenomenon of vacuum pump blowing when printing. The blowing is easy to make the suction between the film and the photosensitive film of PS version not solid and tight, and there is a gap, resulting in quality problems

6. Selection of vacuum degree of air extraction. When the vacuum pump pumps air to the selected value, the vacuum pump automatically stops pumping. When the vacuum degree in the air chamber decreases, the vacuum pump automatically starts pumping air to a certain value of vacuum degree. When the negative pressure gauge (vacuum pressure gauge) reaches the range of 300 ~ 650mm/hg, the gallium iodide lamp can be opened for exposure. If the negative pressure gauge is broken, it should be repaired and replaced to ensure that the indicator needle is sensitive, accurate and properly programmed

source: packaging and printing

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