Heidelberg K series offset press failure and elimination (3)

2 Unstable delivery drive
A. Reasons of the above example 5
B. The footprint is larger in area and the ink layer is thicker, resulting in a greater force required to strip the blanket when the sheet is peeled off. When the end of the sheet is still printing, the impression cylinder has handed the paper to the receiving tray for teething due to delivery. It is impossible to completely synchronize the movement of the teeth with the roller.
In particular, when the delivery bite row moves away from the sprocket for linear trajectory movement, the speed is significantly reduced, so that the printed sheet is not tightly wrapped around the impression cylinder, but the printing paper must be attached to the rubber cylinder and the printing is completed. The dry imprint is facing the delivery lever and it is very easy for the tail of the sheet to be contaminated due to the fact that the impression roller has not bitten the paper.
Ghosting, wrinkling, and coiling (printed sheets are wound on a high-speed rotating blanket cylinder under the effect of ink adhesion, and it is estimated that the maximum adhesive force on a sheet with a width of 700 mm can reach 70 kg), or the overprinting of the tail is not allowed; The reason for this failure is difficult for users to eliminate. The fundamental reason is that the design of the machine structure is irrational and the drum is not properly arranged (only from the overprinting process on the one hand);
3 Roller lining bad, improper printing pressure;
4 The blanket is not tensioned or slanted;
Exclusion: 1A. Repair the left and right fixed guide rails, repair the worn surface, especially the top and bottom dead points of the guide rail are the most severely worn. The brush plating method is used for on-site operation, and then grinding, convenient and quick, saving labor and materials;
B, replace the needle roller bearing, specifications 12X15X10, if not purchased, can be processed on behalf of the roller, the outer quenching HRc40-45;
C. Surveying and processing sector gears, or replacing spare parts;
D, if the Liao 8 taper pin is broken soon after it was discovered, the shaft has not been worn, then only need to remove the broken pin, re-enter the new pin positioning; if found, the shaft has worn, only brush plating Axis, reaming, you can do more with less.
To avoid the troublesome disassembly and installation, if the bearing fails to use domestic 20 bearing alternatives;
2A. Same as above method 5
B. Thinning the ink layer, lowering the viscosity, improving the printability of the paper, or considering it from the process and production arrangements. In short,
All this is to try to reduce the release force of the sheet from the rubber roller;
C. The solution to this problem is to improve the structural design of the printing press. When the paper is bitten as much as possible, only a small part of the paper tail is still in printing, and a three-drum must be completed before the straight-line movement of the receiving teeth. Equal-diameter offset presses meet this requirement. Of course, large-scale improvement designs only make sense for printer manufacturers. Not to mention that the K-series machines are the early products of Heidelberg, and they are transitional products from the letterpress to the offset. I must do it for nothing.