Reasons and solutions for the bite of the edge of the offset bite

After a sheet-fed offset press runs for a period of time, the various parts have different degrees of wear, especially the open cams, bumps, tooth pads, and tooth bases. When the paper is printed, the transfer cannot be performed normally, and it is often easy to bite. The paper edge was bitten, causing overprinting inaccuracies. The edge of the paper edge was inaccurate. The printed product was torn and unsightly, and the quality of the printed product was affected.
1. In the process of the delivery of the offset printing machine, the failure of the bite edge of the paper should be comprehensively analyzed. The difference should be treated carefully. Check the delivery bite too close to the position of the roller teether, and make the paper in the printing paper transfer process. The bite of the mouth bite broken, the solution is to properly cross open.
2. Under normal circumstances, the size of the impression roller and delivery teeth of the offset press is about 12mm. The distance between the roller and the delivery paper cannot be too large, so that the bite of the delivery teeth is too large. The continuity of the paper edge was broken and the position remained unchanged. Found that such failures are to find the cause in the paper-feeding teeth and drum teeth, will slow the offset press, carefully check the paper-feeding teeth and the transfer of paper teeth, the process is accurate in place, the teeth are too slow or the angle of the teeth Large, but easily lead to paper edge bite broken, check the paper feed teeth cam teeth wear, if the cam wear is serious, repair welding or replacement of new parts may be required. It is required that the paper feeding teeth and the large roller teeth control the paper at the same time when the paper feeding teeth hand the paper to the impression roller.
3. The teeth of the bite cut caused by the improper adjustment of the teeth of the bite row in the offset part of the offset printing are inconsistent with the level of the teeth of the teeth, or the pad is not straight, so that the individual teeth are not open enough, or not Zhang closed. Therefore, papermaking paper bite the edge of the paper. Solution: Reposition the tooth pads of the delivery bite row to make it straight and uniform, and then carefully adjust its bite force. Adjusting the bite force of each bite can use a 80g/m2 kraft paper, extend into the teeth, pull it out by hand, and test the size of the bite force.
4. The front gauge position adjustment is not good, so that the roller bite bite the paper too much, so that the bite distance of the delivery teeth is too much, so the paper will bite the edge of the mouth during the handover process. Solution: Adjust the distance between the front regulation paper and control the 3-5mm bite distance.
5. The edge of the offset nip paper is bitten, the paper breaks irregularly, and the break is wide for a while and becomes narrow again. This phenomenon is generally caused by the inconsistent elasticity of the tape on the sheet feeder. In addition, when the paper is turned on, it can be seen whether the pressure roller of the feed line can rotate flexibly. Turn off the offset press to see if the time for the paper to reach the front gauge is appropriate. Under normal circumstances, it is advisable that the current gauge has a distance of 8-10 mm. If it is not appropriate, adjustments are needed.
6. The main point of biting the edge of the mouth is that the delivery position of the delivery teeth and the roller teeth is not on the public line, or the delivery time of the delivery teeth and roller teeth is too long. Solution: First, adjust the position of their transfer, use the hands to move the machine during the adjustment, check and give corrective action; second, shorten the delivery parallel time of the delivery teeth and roller teeth.
7. The edge of the paper caused by the paper is broken. In the papermaking process, the paper is formed of fibers that are intertwined with each other, resulting in uneven density. There are many trachomas and voids in the structure, and the paper surface is uneven. Therefore, a certain amount of fillers, rubber compounds, color materials, etc. must be added to improve the surface of the paper. Smoothness, reduce paper transparency, reduce paper absorbency, increase paper toughness, etc. If the paper is too dry, poor fiber toughness, crisp, loose paper, poor flatness and other reasons, it will easily cause the paper to break in the process of paper feeding, short gauge, and embossing.
In summary, there are three forms of failures that occur when the edge of the mouthpiece is bitten during the offset printing process:
1 The paper bite was broken continuously and the location of the damage was not changed. This reason is that the transfer teeth and roller teeth are not properly connected or the teeth and drum teeth are improperly adjusted.
2 Not all of the edges of the paper are bitten, but instead of being bitten and partially broken, they have regularity. This is mainly due to the reason that the paper collection system is receiving the paper. Pay attention to adjust the bite force of the delivery bar.
3 When the jaws of the paper break, they are big and small, good for a while, bad for a while, and not regular. This phenomenon is generally due to the improper adjustment of the offset press feeder, or the improper adjustment of the height of the front gauge. These two parts must be adjusted separately.
In the daily work, offset printing, rules, stamping, and paper collection must be properly adjusted. The edges of the seams are punctured and related to the components. The worn open teeth require welding and replacement. The accessories should not be tampered with after malfunctions occur, avoid disturbances, and bring a series of process failures. It is necessary to make reasonable adjustments according to the data required in the maneuvering relationship table of the offset press manual, to deliver paper teeth, drum teeth, and delivery teeth. The level of the three big bite paper conveying parts of the pad must be adjusted to be consistent. The closing time and the closing size of the three parts of the paper handing tooth, the roller tooth and the receiving tooth pad must be the same, and the handing over is accurate and in place. Some problems that should be paid attention to during the adjustment process should be taken care of.

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