Troubleshooting method for the bite of the sheet-fed offset printing machine
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After the sheetfed offset printing machine has been running for a period of time, due to the different degrees of wear of the various parts, especially the parts of the open cam, the bump, the tooth pad and the socket, the paper transfer during the printing process cannot be performed normally. It is often easy to bite the edge of the paper. After the edge of the paper is bitten and damaged, the pre-specified position is not allowed. The printing sheet has errors in the series of paper transfer from the transfer paper, the drum bite, and the pick-up bite, which causes the overprinting to be inaccurate, the printed product is bitten and the quality of the printed product is affected. influences. In the actual work, the failure of the bite paper edge is formed by many reasons. To eliminate this fault, it is necessary to find the cause and solve the problem from the following points.
1. Under normal circumstances, the bite distance of the size offset printing machine is about 12mm, so that the distance between the drum biting and the paper feeding teeth is too large, so that the biting distance of the receiving tooth is too much, if the biting mouth The continuity of the paper edge is bitten and the position of the bite is unchanged. If such a fault is found, it is necessary to find the cause on the transfer paper and the large tooth of the drum, open the offset press, and carefully check the process of transferring the paper between the transfer paper and the large tooth of the drum, whether it is accurate in place, the tooth is too slow or the tooth is opened. The angle is large, and the paper edge bite is broken. At the same time, the wear of the tooth of the paper tooth is checked. If the cam has serious wear, the repair welding can be performed, or a new piece can be replaced, and the paper is required to be transferred. When the paper is fed to the large teeth of the drum, the paper feed and the large teeth of the drum simultaneously control the paper.
2. In the process of receiving the paper, the offsetting of the biting paper is comprehensively analyzed, and the difference is treated. Carefully check whether the position of the receiving teeth and the tube biting are too close, so that the paper is transferred during the printing process. The edge of the bite of the paper is broken. The solution is to cross it properly.
3. The bite paper edge of the biting row of the offsetting machine of the offset printing machine is bitten by the improperly adjusted bite. Mainly because the height of the teeth of each bite is inconsistent, or the pad is not straight, so that the individual teeth are not enlarged enough, or do not open, thus causing the paper to bite the edge of the paper. The solution is to re-adjust the individual pads of the delivery tray so that it is straight, the height is consistent, and then carefully adjust the bite force. To adjust the teeth of each bite, use a small piece of 80g/m2 kraft paper, put it into the teeth, and pull it out by hand to test the bite force.
4. The position adjustment of the front gauge is not good, so that the distance between the drum biting teeth and the paper is too much, so that the biting distance of the paper receiving teeth is too much, so the paper bite edge is broken during the handover process. The solution is to properly adjust the distance of the front gauge to bite the paper and control the bite distance of 3-5mm.
5, the bite paper edge is bitten, the paper is not broken regularly, and the mouth is wide for a while, narrow for a while, this phenomenon is generally due to the inconsistency of the tape on the offset machine wheel paper, in addition, driving to see the paper line Whether the belt's pressure roller can rotate flexibly. Slowly open the offset printing machine to see if the time for the paper to reach the front gauge is appropriate. Under normal circumstances, the requirement is that when the current gauge reaches the paper receiving position, the distance of the paper side road gauge is 8-10mm.
6. The main reason why the bite paper is bitten is that the delivery position of the paper-carrying teeth and the roller-nose teeth is not on the public normal line, or the parallel connection time of the paper-carrying teeth and the drum-biting teeth is too long, and the first is to adjust their handover. Position, adjust the machine with both hands, carefully check and correct; Second, the parallel timing of the delivery of the paper-carrying teeth and the roller-cutter teeth can be appropriately shortened.
In short, there are three types of failures in the paper feeding process when the bite paper is bitten:
1 The paper bite is bitten and the position is unchanged. The reason for this is that the paper and the roller are not accurate.
2The paper bite is not bitten every single piece, but a few sheets are not bitten, and there is a certain regularity, mainly the problem of the delivery line of the delivery system. Care should be taken to adjust the bite force adjustment of the delivery tray so that all bite forces on the row are uniform.
3 The break of the edge of the paper is large and small, good for a while, bad for a while, and does not have regularity. This phenomenon is generally caused by improper adjustment of the offset printer, or the height adjustment of the front gauge. If it is not appropriate, adjust these two parts separately.
In daily work, all systems from paper feeding, rules, imprinting, and delivery should be properly adjusted. The bite at the bite is closely related to each system. Wearable open cams require welding and replacement of new fittings. There is a problem, do not tamper, avoid a series of process failures after adjusting the disorder, and at the same time, according to the data required in the maneuvering table of the offset printing machine instruction manual. Adjustment, the three major parts of the paper feeding tooth, the roller big tooth, and the delivery paper pad must be adjusted in the same time when the paper is transferred. The paper feeding teeth, the large tooth of the roller, the closing time of the delivery pad, the closing size must be the same, and the handover is accurate. It is a few problems that should be paid special attention during the adjustment process when the bite paper is broken.