A special cause of poor paper receiving of the hot

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A special reason for poor paper receiving of the paper receiving tooth row

the Beijing People's printing press purchased by our factory in 1996 can automatically return after the experiment is completed; Recently, the yp4a-1 offset printing machine with 4-color folio produced by the machinery factory often has the problem of poor paper receiving of a row of paper receiving teeth. After others made adjustments and repairs such as tightening the chain, the old disease recurred after less than 10h of normal work

its fault is that when the printing speed is below 6000, there are only oneortwo teeth at one end of the tooth row operation surface, and sometimes they don't pick up the paper. After the printing speed is slightly increased, the whole tooth row almost doesn't pick up the paper, and there is no rule

when I started the maintenance, the operator once warned that the paper receiving tooth row's paper opening plate shook significantly with the passing of each opening roller. It was found that the fastening nut of the fixed rod of the die plate outside the machine wall panel had fallen into the oil. However, after fastening it, the poor paper delivery of the toothed row did not improve. Although there is no fundamental change in adjusting the balanced gripping force of this row's teeth at the paper receiving table several times, even if it is adjusted to be as consistent as possible with other normal tooth rows, the paper receiving effect is still different

so where is the root cause of the fault? After analysis, I think that some teeth of this tooth row can't hold the paper in their mouths, and the connection with the roller is finally successful. The poor aluminum alloy paper for electrical purposes is related, while the other five rows of teeth are basically good, indicating that the handover time is basically normal. In this case, the problem must lie in this tooth row

later, during a tooth adjustment and counting at the paper receiving table, I occasionally heard a slight irregular creak when the tooth row turned around the curve on the paper receiving sprocket. After repeated comparison and audition, there was no such slight abnormal sound in other dental rows. This indicates that there is abnormal friction in the tooth row during running and steering, which may be due to some obstacles in the movement of the tooth row on the chain. So I decided to take the tooth row off the chain for inspection

click and move the tooth to the upper part of the inclined part of the paper receiving drum, that is, the appropriate place where the flat guide rail of the chain is connected with the downward inclined guide rail. On the transmission surface, retreat the tooth row shaft head cover and the threaded long pin shaft connected with the chain to be flush with the chain, and then take out the tooth row shaft head cover at this end diagonally above, and then pull the tooth row towards the transmission surface, so as to pull out the shaft head cover of the operation surface from the threaded long pin shaft and take the tooth row off the machine

after cleaning both ends of the tooth row, it was found that there were obvious friction marks on the outer end face of the shaft head cover of the two tooth bar relative to the rivet head of the chain link pin located in the middle of the shaft head cover. This proves that the tooth row does have irregular friction stagnation when it is connected with the drum every time

in this regard, I use an angle grinding wheel to properly grind off the rivet head of the relevant chain link pin shaft under the condition of ensuring fire safety

after assembly, when the test print runs to 7000 prints/h (because the speed limit is 7000, its second, gathering 400+ industry elites, and third and fourth parts are printed/h by the classification method through fire resistance test), the paper delivery of this tooth row is completely normal

the above description shows that the root cause of the poor paper receiving failure of the toothed row originally lies in the irregular friction stagnation of the toothed row when the chain runs and turns

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