Adjustment skills of teeth in the most popular off

2022-08-14
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Adjustment skills of the teeth of the offset press

get out of the misunderstanding of the teeth adjustment of the offset press

the operator of the printing press knows that the adjustment of the teeth of the offset press is one of the work often carried out in the printing production. However, in the process of adjustment, there are some misunderstandings to varying degrees. Next, the author gives a brief introduction to the correct adjustment of the teeth of single (double) color machine and four-color machine

single (double) color machine

single (double) color machine (taking J2108 machine and J2205 machine as an example) is divided into paper delivery teeth, embossing cylinder teeth, and paper feeding chain teeth. In the printing process, thin paper (such as 52g/m2 paper) is often folded at a tooth of the impression cylinder, or rubberized when printing coated paper. At this time, the operator will often stop the machine, debug the small spring of the tooth separately, tighten or loosen the small spring, and sometimes even remove a tooth piece from the tooth seat, but these practices are incorrect. Excessive stiffening will make the small spring lose elasticity and cause dead teeth; Too much looseness will cause the small spring to fall off and press on the impression cylinder, damaging the impression cylinder. The correct adjustment method is as follows:

Step 1: move the offset press to a place convenient for operation, find the positioning block and positioning screw of the toothing shaft, and pad in a piece of paper with a thickness of about 0.4mm

step 2: loosen the fastening screws of all grippers so that they are not closed

step 3: make the tooth piece lean against the tooth pad and make it have a certain pressure, then tighten the fastening screw, and put a 0.1mm thick kraft paper strip between the tooth piece and the tooth pad to measure its gripping force

step 4: adjust the small springs and screws one by one so that all the kraft paper strips held by the teeth are used to encourage the spring * mass components; The other is that the average load hydraulic cylinder applied to the test piece has roughly the same tension, and at the same time, adjust the same gap between each gripper and the tooth base to make the opening time of the gripper consistent

step 5: remove the paper between the positioning screw and the positioning block, so that all teeth can increase the same gripping force

in this way, the overall adjustment of the gripper is not only faster, but also the gripping force of all the grippers is the same, which avoids frequent shutdown caused by adjusting a certain gripper alone, so as to avoid the phenomenon of tissue change and repeated debugging caused by heating of the sample. The adjustment of the paper delivery teeth of J2108 machine is basically the same as that of the teeth of the imprint cylinder, but it should be noted that the paper between the positioning block and the positioning screw should be thinner during adjustment

in actual printing, it often occurs that a gripper on the chain row does not put paper at the paper receiving table and takes away the paper. Some operators suddenly press the stop button during the normal printing process of the printing machine, trying to find the teeth without paper. But doing so will not only damage the printing press, but also make it difficult to find the faulty tooth, which is labor-consuming and time-consuming. The correct way is to shut down the machine first, put a 0.25mm gasket into the contact between the toothing block of the chain row and the toothing pad shaft, loosen all the toothing fastening screws to make the tooth piece and the tooth base close together, then tighten the screws, put a 0.1mm thick paper piece between the tooth piece and the tooth pad, adjust the screws to make all the teeth have the same gripping force, and then take out the gasket. Adjust all chain rows like this and start printing again. The phenomenon that the chain row does not put paper in its teeth can disappear

four color machine

the imprint cylinder and paper transfer cylinder of the four color machine are generally double diameter cylinders, on which there are two rows of teeth, so the adjustment is more complex. However, it is not correct to adjust the tooth holding spring alone or to adjust the tooth holding of an imprinting cylinder alone in order to save time. Because the four-color machine generally has four embossing cylinders, and each embossing cylinder has two rows of teeth. For example, the horizontal tensile testing machine. If the technical parameters of the horizontal tensile testing machine are only adjusted for a certain cylinder or a certain row of teeth, it is easy to cause the uneven force of the teeth of the embossing cylinder, resulting in inaccurate four-color overprinting or image and text ghosting, which seriously affects the quality of printing products. The correct method is to adjust 8 rows of teeth at the same time. Now take Shanghai Gauss four-color machine as an example

step 1: open the protective cover of the embossing cylinder, jog the machine, and expose the teeth of the embossing cylinder

step 2: loosen the screw on the roller controlling the opening and closing of the gripper on the gripper shaft with a 5mm Allen wrench, and then rotate the roller shaft by about 60 with a monkey wrench. At this time, all the gripper pieces are about 0.05mm away from the tooth pad

step 3: loosen all the fastening screws of tooth gripping, make the tooth piece leave the tooth pad, and clean the dirt on the tooth piece and the tooth pad

step 4: put all teeth on the tooth pad, tighten the fastening screws of each tooth, and then put a 0.05mm thick steel sheet between the tooth pad and the tooth pad, adjust the small spring on the tooth base, and pull the steel sheet, so that the steel sheet can be pulled and has a certain resistance

step 5: after adjusting all grippers, turn the opening and closing gripper rollers back to their original positions and tighten the fastening screws. In this way, all grippers will increase the same gripping force to ensure the accuracy of overprint of printed matter

in general, the tooth adjustment of offset press mostly follows the same rule. That is, first make the tooth piece leave the tooth pad a certain distance through a certain structure (different structures of printing machines), and then make unified adjustment to the teeth, so that the force of each tooth holding small spring is uniform, and then make the teeth hold the same pressure by fixing the large spring or torsion spring on the tooth holding shaft. Remember not to monotonously increase the pressure by holding the small spring on the tooth. In this way, we can get out of the misunderstanding of adjusting the tooth shaft of offset press and improve the quality of printing products

relying on the statement of aluminum processing projects such as An'an precision aluminum, Chenlong aluminum and Shenwei Electronic Industrial Park:

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