When feeding paper, the paper will be paused regularly during the process from the paper feed roller to the paperboard. We call this phenomenon a paper feed pause. If this pause is too obvious, it will affect the positioning accuracy of the paper at the front gauge, resulting in inaccurate overprinting.
Cause Analysis
There are three main reasons for the occurrence of paper feed pauses.
(1) The paper machine camshaft is not working properly. The structure of the paper feeder includes two camshafts, one is a small camshaft that controls the operation of the paper feeding mechanism, and the other is a long camshaft that controls the operation of the paper-feeding mechanism. During the operation of the paper machine, the linear speeds of the two camshafts running one week are not uniform and are constantly changing. Since the cam positions on the camshaft are different, the resulting linear velocity is different. When the cam facets are turned to the cam face (ie, from the cam low point to the cam high point), there is a resistance to the camshaft movement, and vice versa. There will be a boost to the camshaft movement. In the process of paper feeding, this process appears as a slight pause, and when this phenomenon is too obvious, it will cause paper feeding failure.
(2) The matching precision of the parts and gears of the paper feeder is low (such as the meshing accuracy of the gear, the matching precision of the Feida valve, the shaft and the shaft hole, etc.). In addition, if these parts are too tight at a certain position, it will cause the paper machine to pause when it is turned to this position.
(3) The delivery time of the paper feed nozzle and the paper feed roller is incorrect. For example, after the paper feed nozzle is closed to the limit position, there is still residual suction, so that when the paper take-up wheel transfers the paper to the paperboard, the paper feed nozzle will bring back the paper, causing the paper to stop.
Troubleshooting
For paper stalls, we can take the following measures to eliminate them.
1. Ensure the matching precision of the various parts and gears of the paper feeder The operation of the conveyor system of the paper feeder mainly relies on the universal coupling of the paper feeder to drive the gears of the paper feeder to rotate. The paper machine gear is connected with each function shaft to drive the paper feeder to complete the paper feeding movement. The transmission accuracy of the gear directly affects the movement of the relevant components, and the matching accuracy of each component also affects the normal transmission of the gear. In general, the possibility of gear influence is not great unless the gear is damaged. During the routine maintenance and maintenance of the equipment, the gears of the paper feeder should be inspected regularly. If there is any damage, it must be replaced in time to ensure the normal operation of the paper feeder.
2. Adjusting the delivery time of the paper feed nozzle and the paper feed roller The paper transfer mechanism is mainly composed of a transfer cam, a connecting rod and a transfer nozzle. There are many reasons for the incorrect timing of the transfer of the paper feed nozzle and the paper feed roller. The appropriate adjustment can be used to reduce the hidden troubles, thus ensuring smooth production.
(1) Adjusting the suction of the transfer nozzle The adjustment method of the suction of the transfer nozzle is the same as the adjustment method of the suction of the separation nozzle, that is, adjusting the valve of the right side of the feeder, and rotating the counterclockwise to increase the suction. The amount of gas, and vice versa, reduces the amount of inhalation. In addition, the transfer nozzle and the separation nozzle should be cleaned frequently to keep the air passage clear.
(2) Adjustment of the height of the transfer nozzle The adjustment of the overall height of the two transfer nozzles (ie, the height of the link) can be achieved by changing the relative fulcrum position of the transfer shaft link by the round screw on the link. Under normal circumstances, the height of the paper-feeding nozzle should be about 15mm from the paper surface. If it is too high, it is not easy to pick up the paper. If it is too low, it will easily wipe the image.
(3) Adjusting the working time and position of the platen roller Adjust the falling and lifting time of the platen roller by the platen cam. When the transfer nozzle delivers the paper to the paper feed shaft, the platen roller should drop to hold the paper and feed the paper together with the paper feed shaft. The paper roller is pressed down, and after the paper advances 3 to 6 mm, the paper nozzle can continue to feed the paper. Under normal operation, the transfer speed of the transfer nozzle is synchronized with the paper feed shaft, so there is no paper grab. However, if the equipment is used for a long time, the paper feed nozzle will control the cam wear, so that the paper feed nozzle paper speed is lower than the paper feed shaft feed speed. At this point, the paper feed nozzle should first put the paper, then press the paper roller to press the paper, so as to avoid the phenomenon of paper grabbing, causing the paper feed to stop.
(4) Adjusting the pressure of the paper feed roller The paper feed roller is generally made of hard rubber or nylon. The pressure of the left and right paper feed rollers should be adjusted to ensure the smooth conveyance of the paper. Under normal circumstances, the greater the pressure adjustment of the paper feed roller, the greater the friction, the more the paper can move at the same speed as the paper feed shaft; the smaller the pressure of the paper feed roller is adjusted, the smaller the friction, which may result in The amount of paper slippage increases, so that the paper cannot move at the same speed as the paper feed shaft, and the paper skew occurs. Therefore, the pressure of the pickup roller is very important and should be carefully adjusted.
After the adjustment is completed, the correct transfer of the paper feed nozzle and the paper feed roller should be: the paper feed roller falls in contact with the paper feed shaft. After the rotation is 1~2mm, the paper feed nozzle stops inhaling, puts the paper and starts to move backward. The paper nozzle must be placed before the return stroke, that is, a unit action is completed, and then the repetitive motion is entered so that the paper is always in a controlled state during the handover process.
　　 The above content is selected from the third issue of 2011, Printing and Printing , Packaging and Decoration, and more journal content. Please pay attention to the journal channel.
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