Unstable paper feeding machine failure and troubleshooting

Paper feeders are an indispensable part of modern sheetfed offset presses. Its performance is related to the machine's running speed and the overprint accuracy of the product to some extent. The paper feeder shall ensure that the paper is separated smoothly and accurately, conveyed to the positioning mechanism, and then input into the printing device. Due to the blind pursuit of output by some printing manufacturers, the equipment (paper feeder) is not well-maintained, and with the long time of use of the machine, paper feeders often have problems with paper feed instability. The following analysis of some of the problems encountered by the author at work is as follows for your reference.
First, the cardan shaft is faulty. Because some printing machine cardan shaft fork exposed, making paper powder and other fine particles easily stay in the cardan shaft fork and the connection between the ball, over time, resulting in two fork wear, with As the gap increases, vibration will occur during transmission, which will result in chattering on the paper, resulting in unstable paper feeding.
Solution: Replace the worn cardan shaft yoke and connecting ball. When replacing the cardan shaft fork, pay attention to make the fork at both ends into a plane, otherwise it will generate a new vibration source.
Second, the miscellaneous valve maintenance is not a good cause of hidden troubles because often paper powder, sand suction nozzle suction valve, over time, intensified the wear of the valve body and valve housing, plus some operators improper operation, damage the valve body The wind slot makes the feed nozzle work to the extreme position. When the take-up roller is pressed down, the suction nozzle still has suction force, and the paper feeding process generates a pause. This phenomenon has a great influence on the accuracy of overprinting of products, which seriously plagues operators.
Solution: Remove the valve, observe the valve body of the wind groove, if the wear is serious, you can wash the wind tank, use the electrode to fill the tail of the wind tank about 2-4mm (according to the pause time and length) .
Third, the wear of the gear and the break of the pin A pair of bevel gears on the side of the clutch, because the whole gear is exposed, the working environment is rather harsh. If the improper maintenance, it is easy to make the tooth surface wear worse, and the bevel gear and the inside of the key The coordination relationship becomes a gap fit, resulting in a series of unsteady phenomena such as paper movement jitter. Sometimes due to long-term lack of oil rust rust or other parts of the valve caused by the failure of excessive force caused by a pin break, causing the host and the feeder with the wrong time, causing trouble printing.
Solution: If the gear or square key is worn, replace it. If the pin is broken, you should find out the reason of the break and carefully check whether the pin has any heat or iron powder. It should be eliminated according to the actual situation. .
Of course, in addition to the above-mentioned factors that cause the paper to move unevenly, brake spring pressure springs are too loose, the bearing of the paper feed roller is turbulent, and the separation head is worn into the bolts of the connecting rods. Again one by one.