An example of ink bar exclusion of the most popula

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One case of ink bar exclusion of offset printing products

our factory purchased a second-hand imported Heidelberg four-way monochrome Offset printing machine from other places a few years ago, and the printing effect was still relatively ideal at that time. But recently, we found that the ink bar will appear when printing the full page on the spot with this machine, and the ink depth is inconsistent. At first, I thought it was too heavy to roll the plate, After inspection, it is found that the two cylinders of the four landing rollers have the same force (the width of the first three landing rollers is 4mm, and the width of the fourth ink receiving pressure bar is 3mm. The product meets the relevant requirements of the tensile stress relaxation test of steel at room temperature in the standards of gb/t 10120 (1) 996 metal stress relaxation test method and ASTM E328 (2) 008 material and structure stress relaxation test method and gb/t20065 (2) 006 rib reinforcement for prestressed concrete). Then, we took down all the four landing rollers and checked the bearings of the shaft sleeves at both ends. It was found that the bearings in three shaft sleeves at the flywheel end were worn out, and almost all the needles in them fell out, leaving only the needle clamp and the shell. We thought we found the problem, but after replacing one of the three shaft sleeves, the printing effect was still not improved

then, we can use medium ink in all the investment scope of "uniform ink". The existing two ink string rollers have radial runout during operation, but the effect is still not improved after replacing their bearings

the factor of ink roller is basically eliminated, so it is natural to suspect the water roller. First of all, take down the two inking rollers, lift the four inking rollers to the position close to the plate, and let the printing plate cylinder run for a few weeks. At this time, we found that the printing plate not only has uniform ink color, but also has no trace of ink bars. After further inspection, it was found that the water string steel roll had obvious radial runout. Measured with a dial indicator, the radial runout was as high as 1.02mm. Finally, we loosened the fastening screws at both ends of the water string roller for recalibration, and finally the fault was completely eliminated

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