Talking about the timing adjustment of the side gauge and the transfer paper from the overprinting fault
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When operating the J2205 offset press, sometimes it encounters such a fault: the paper feed distance of the side gauge is very limited, and usually the paper conveyed by the paper feeder, the off-side prescribed baffle must be within 4 mm to be pulled in place, if the paper is fed With a slight deviation, it is easy to produce the phenomenon of pulling out or pulling over the head. At the same time, it is accompanied by a vertical overprinting fault that is not in place.
At first, it was suspected that there was a problem with the pull gauge. After inspection, the pull gauge was not abnormal, and when the empty car was opened, the paper strip was placed under the pull paper wheel and the maximum pull distance could reach 11 mm. After eliminating the pull gauge problem, the next step is to check the transfer paper. The distance between the dental pad and the paper feed table is appropriate. The force of each tooth is even and the action is the same. When the car is driven to 77°, the roller is opened and closed. Disengaged from the closed jaw, it corresponds to the pull-up time.
Finally, we put a whole printed sheet on the paper positioning table of the paper feeding table, and slowly clicked on the car to check it repeatedly. Finally, we found that the paper feeding paper was holding the paper in advance, and the advance amount was as much as 5°. After discovering the problem, we made a more elaborate adjustment to the handover time of the pull gauge and the transfer paper. In order to ensure that the paper is able to accurately position and transport the paper while the pull gauge is lifted, firstly, when adjusting the lifting time of the pull gauge, the car is pulled to 77°, and the printed sample is torn into a paper strip. Under the paper pull roller, adjust the cam that controls the swinging movement of the paper feed roller so that the paper pull roller has no pressure on the paper; then loosen the fastening screw of the paper cutter closing claw, rotate the position of the bump, and simultaneously use The strip test detects the condition of the paper, so that the paper has just caught the paper; finally, the fastening screw of the bump is locked. After repeated adjustments, the printed matter is printed accurately and the fault is completely eliminated.
After troubleshooting, we analyzed and summarized the problem.
1. Whether the time transfer relationship between the side pull gauge and the transfer paper teeth is coordinated and accurate is the key to ensure accurate overprinting. The adjustment should be absolutely accurate, ensuring that the side gauge pull time and the paper feed time do not interfere with each other.
2. Adjust the timing of the paper-cutting teeth when the paper is actually just holding the paper. We have previously adjusted the timing of the closing of the delivery paper. The conventional adjustment method will produce a large error. The reason is that during the process of closing the gums of the transfer paper, when the open roller moves away from the high point of the closed jaw, the two total springs of the transfer shaft push the dental shaft and the upper teeth toward the tooth. The pad rotates in the direction. When the tooth is pressed against the paper between the tooth and the pad (ie, the paper has just exerted force on the paper), the roller does not leave the closed bump, but only from this point on. The force of the closed teeth on the roller begins to gradually decrease, and the tension of the total spring of the two transfer shafts passes through the dental shaft and the braces. Small springs and teeth, and finally applied to the paper. The force on the pad begins to increase gradually. Only when the force of the closed teeth on the roller is gradually reduced to zero, the tension of the total spring of the transfer shaft acts on the paper. When the force on the pad reaches a maximum, the opening and closing of the tooth roller begins to leave the closed tooth bump. From the beginning of the transfer of the paper, there is a force to hold the paper, and the process of the roller leaving the closed jaw (the maximum force of the paper) reaches 3°. If the force of the paper is too large or the force of each tooth is uneven, the movement will be inconsistent and the process will be longer.
3. Because the printed paper has a certain thickness, the accurate time for picking up the side gauge should tear the printed paper into a paper strip and put it under the paper pull wheel for testing. The paper pull roller should have no pressure on the printed sheet, and should not be used. The knurling wheel below the pull paper wheel and the pull paper wheel is just off.
The above viewpoint is a problem that must be paid attention to when adjusting the time handover relationship between the side gauge and the transfer paper.