Printer tearing troubles and solutions

In the production process of each printing factory, the phenomenon of hand-off tearing is common. The occurrence of such failure not only brings certain troubles to the operators, but also affects the quality of the products. Tear-off faults are sometimes simpler, and adjustments will soon be resolved, sometimes more complicated, and can be resolved through exploration. In order to prevent operators from taking detours when troubleshooting paper tears, we will now introduce our approach as follows.

Our factory has a J2108 offset press that does not tear paper when printing 100g/m2 or more paper, and tear paper when printing 80g/m2 or less; it tears paper at high speed and does not tear paper at low speed. After this situation appeared, it added a lot of trouble to maintenance personnel. Before it appeared, due to the better accuracy of the machine, it was mainly used for the printing of covers, color photos, maps and other fine products. With the increase in the number of years of use, the accuracy has dropped, and the printer has been changed to print and print. In the printing process, tearing occurred. At the beginning of the inspection, it was considered that after the machine was used for several years, the tooth pads of the pads were seriously worn, the height was unbalanced, the strength of the crepe paper was inconsistent, and the size of the open teeth was uneven. Therefore, we replaced and adjusted the accessories, but after the test machine, the failure has not been resolved. It seems that the problem is not on the gripper, will it be related to the handover time?

Observed by the low-speed operation, the paper runs straight, the time before reaching the front gauge is appropriate, the swing arm grippers open the teeth in a uniform manner, the amount of paper pick-up is 7 mm, and the pick-up force is not small. The swing arm tooth and the embossed tooth have a smooth transition, the time is right, there is no tearing paper. There is no abnormality when the embossed and delivery teeth are transferred. After repeated presses to move the machine, it was found that there was a take-up tooth row at the time of hand-over. He could hear the sound of hanging paper and there were several small tears in the mouth. Based on this situation, we conducted an analysis and concluded that there was an error in the delivery time between the delivery tooth row and the embossed gum, that the delivery teeth were closed somewhat earlier, that the time between two teeth transfer to catch the paper was short, and the embossed teeth were short When the teeth have not been opened yet, the receiving tooth row has moved forward with the paper, and grabs paper, so it will tear the paper. According to the principle of transfer of the printing press, the paper needs to be accurate and smooth during the handover, that is to say, there is a period of constant speed operation after the two rows of teeth catch the paper, which is about 2°~3°, and the embossed crepe paper only opens the teeth. , To receive the paper teeth can be carried away paper, time can not be too early nor late, otherwise it is not like the above-mentioned tear paper, or the transfer of instability, the emergence of air throwing paper, paper inconsistent or falling paper.

Why does thick paper do not tear thin paper tear, high-speed tear paper does not tear paper at low speed? Because the thick paper is more than the wood pulp, the tensile strength is great, the toughness is good, and it is not easy to tear the paper. Thin paper, on the other hand, is inferior to thick paper and wood pulp in terms of paper quality, poor in toughness and pulling force, relatively brittle, and easy to be torn. The high-speed tearing of the printing press does not tear the paper at a low speed. The main reason is that during high-speed operation, the vibration makes the running smooth, the delivery time is short and fast, there is a great impact force and inertia, and slight discomfort at the time of the handover will tear the paper; The low-speed operation is smooth, there is no inertia and impact force, and the handover time is slow and long, so it is not easy to tear.

Based on the above analysis, to determine the problem is on the opening plate of the delivery roller, open the dental plate should be adjusted to delay the opening teeth teeth, but the open plate has been adjusted to the limit. We will remove the open plate, press the direction of adjustment, the hole with a round cymbal 6mm long, increase the adjustment margin, after the transformation of the open sprocket installed on the machine, debug tear paper troubleshooting, operation good.