How to eliminate the comprehensive fault of the analytical offset press
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1. The partial overprint caused by the paper path is not allowed. Partial overprinting does not mean that the local position of the paper is relatively slippery during the printing process.
(1) When there are only two pre-specified positions, when the paper arrives at the front gauge, the middle portion protrudes forward, and the softer the paper, the more prominent the situation. Reduce the speed or increase the number of front gauges. So that the paper is accurately positioned in the rules before the day.
(2) The bite force of the individual cavities on the paper feed tooth is insufficient, so that the first four positions of the paper are changed to increase the pressure or replace the tooth pad.
(3) The amount of bite paper in the transfer paper is uneven, and there are many ones, and the side is small, and the portion where the amount of the paper is small is likely to be relatively slipped. Adjust the front gauge to make it evenly.
(4) The bite force of individual teeth on the impression cylinder is insufficient to replace the tooth pad or increase the bite force.
(5) The partial printing pressure is too large, causing the resistance of the paper to advance to increase, thereby causing the paper at the place to be checked to check the blanket and the pad, and re-printing the printing pressure.
(6) The uneven distribution of the surface of the printing plate is unreasonable. The paper is prone to relative sliding, adding ink or reducing printing pressure.
(7) The paper swells through the water, causing the second half of the paper to be conditioned before the paper is printed.
2. The seal caused by water and ink road is not allowed.
(1) Plate loosening Due to the looseness of the printing plate, the position of the print is changed during the printing process, so that overprinting is impossible. Adjust the fastening screw and tighten the plate.
(2) The lining under the printing plate is not suitable, so that the embossing becomes larger or smaller, so that the overprinting is not allowed to re-detect the thickness of the lining, and the lining is re-padded according to the technical specification.
(3) The loosening of the rubber market Because the blanket is loose, the position of each print is changed, resulting in inaccurate overprinting.
(4) The amount of water is too large, so that the tension of the paper becomes small, and the paper is easily subjected to tensile deformation to reduce the amount of water.
(5) The amount of ink is too large, causing the paper to slide in the cavities to lower the viscosity of the ink.
3. The overprinting caused by the plate making part is not allowed.
(1) When the imposition is not allowed to print, the cross line or the angle line is used as the reference line, and the imposition type is also based on the cross-line moving average. If the positional alignment between the graphic and the rule line is inaccurate, it is extremely difficult, and sometimes impossible, to overprint accurately when printing. Therefore, the precision of imposition should be maximized.
(2) If the drying is not allowed, it is generally not a problem. It is easy to have such problems when the two are exposed to the sun or two. Therefore, you should avoid the sun and the sun as much as possible. If you must do this, you should first use the paper.
(3) Deformation of the plate when the plate is pulled Due to the poor resistance of the plate to deformation, it is prone to deformation after being subjected to a large force, and sometimes even a crack may occur. Therefore, it is not advisable to use too much force when pulling the plate. If you can't pull it, you should look for the reason carefully.
(4) Overprinting caused by process layout is not allowed
1 Multi-color overprinting is prone to overprinting. The more times the overprinting is, the more likely the error is. Therefore, the number of overprinting should be minimized. 2 The anti-white characters or lines of multi-color overprinting are most likely to be overprinted. In these cases, special colors should be used instead of overprinting. In addition, a reasonable process can be used to minimize the number of overprints and minimize the possibility of errors.
1. The paper path will cause the body to be inaccurate.
(1) Inaccurate positioning of the rules Check the working conditions of the front gauge and the survey gauge carefully. When the paper is positioned beforehand, when the paper is positioned, adjust it according to the requirements of the manual. At the same time, it is necessary to pay attention to whether the height of the front gauge and the gauge meet the requirements.
(2) Inaccurate paper feeding
1 The paper is shaken when the paper is picked up, causing the transfer to be unstable: the plug of the transfer paper is adjusted to keep it stationary on the paperboard, and the transition is the most gentle;
2 axial movement of the paper feed paper when picking paper: adjust the axial lock nut so that it has a 0.03mm series movement amount;
3 The bite force of the paper tooth is insufficient, the paper slides: increase the bite force, especially at high speed, this should be noted (mainly caused by the inertia of the paper);
4 The timing of opening and closing the teeth of the paper is not accurate: re-adjust the opening and closing time.
(3) Inaccurate coordination between the transfer paper and the rule
1 When the paper is not taken, the paper has been released from the rule: the adjustment rule has a common handover time between the paper and the rule;
2The rule has not been positioned yet: the paper is taken from the paper, and the above adjustment is made;
3 When the paper feed paper is removed from the paperboard, the rules have not been placed: the adjustment rules are made to release the paper in advance;
4 The height of the upper paddle is not suitable: it is too low, it is easy to impact the paper and make the paper shift; too high, the paper will be pulled up when the paper is fed, and the position of the paper will change. The height position on the cardboard should be carefully checked. Generally, the height should be: paper thickness +0.2mm, which is consistent with the height of the front and side gauge plates.
(4) Inaccurate handover between the transfer paper and the front transfer cylinder (or impression cylinder)
1 handover time is too short: adjust the position of the corresponding opening and closing cam; 2 the distance between the pads is not suitable: re-adjustment, so that the distance is: paper thickness +0.2mm. However, this distance is generally not suitable for adjustment.
(5) The bite force of the impression cylinder is insufficient, and the paper slides in the impression cylinder
1 The pressure of the tooth piece is too small: increase the pressure of the tooth piece;
2 The friction coefficient of the dental pad is too small: replace the dental pad;
3 The viscosity of the ink is too large, and the viscosity of the ink is reduced by adding an ink or a debonding agent;
4 The surface of the blanket is sticky: replace the blanket;
5 printing pressure is too large: reduce printing pressure.
(6) The bite force of the rear paper feed roller is insufficient, and the paper slides in the teeth. Since the rear transfer roller on the general machine participates in the printing process of the latter half, it is required to be the same as the impression cylinder. The troubleshooting method is the same as above.
(7) The bite force of other roller teeth is insufficient. The troubleshooting method can be carried out by referring to (4) and (5).
(8) The bite force of the delivery chain is insufficient. The troubleshooting method is the same as (6).
(9) The axial movement of all the rollers will cause the overprint to be inaccurate. The axial movement of the rollers is generally a double nut mechanism. If it is found that the axial movement amount exceeds the specified requirement (>0.03mm), adjust the lock nut, generally it should be fully locked, then reverse one-third turn. After adjusting, be sure to lock the nut. Axial thrust bearing wear will also cause axial movement of the drum, and should be replaced if worn. More precisely, it can be detected with a dial indicator.