Our factory introduced a German Heidelberg 102F five-color offset press in 1992. The aircraft's advanced performance and quality are still good, but there are also some problems in use, affecting the safety of equipment and printing quality, the most prominent of which is the bumper problem affecting the safety of equipment. I am engaged in the installation and use of the machine. I am now talking about the reasons for the problem and the improvement of my experience. I will talk about my personal views for my colleagues.
In 1994, a five-color offset press was introduced by a brother factory in Liuzhou. One of the bumpers was pressed out of the roller during the operation of the equipment, causing pressure marks on the pressure roller. The accuracy was severely degraded and could not be used. Repairs required huge amounts of money and time. Only four of them can be used.
In 1995, a similar accident took place in our factory's machinery. The bumper fell off between the pressure roller and the transfer roller. Even though the machine was shut down in time, the bumper was still pressed in 2/3, leaving a 10mm x 3mm on the right side of the cylinder. 1.5mm dents, pressure roller buckling teeth deformation, dental dentition 7 only to varying degrees of cracks, cavities 5 only damage. We spent a lot of effort to remove the scrapped bumper. Check the accuracy of each roller, basically unaffected. After repairing the obviously damaged parts, they continued to use them and gradually found that the overprint was not allowed or unstable. After consultation by experts, it was found that the handover angle was affected and changed.
After analysis, the cause of the accident is that the inner threaded plastic sleeve at both ends of the insurance box is broken due to aging, resulting in the loss of the support and falling off of the bar, and pressing into the roller, causing the cylinder indentation and accuracy to reduce. The bar body is a φ18mm×1080mm brass tube, and the double wall thickness is 4mm, and the extrusion becomes 2.8mm. It can be seen that the roller bears a great pressure load. At the same time causing indentation and precision damage is also the top of the bar head, the head is M10 hexagonal screw, is a hard steel. According to the analysis of the impression on the surface of the impression cylinder, the head is the root cause of the 10mm x 3mm x 1. 5mm dent and the damage of the dental pedestal, the acetabular axis, and the decay of the acetabulum, and the change in the angle of the transfer of the cylinder.
Treatment method: Since the dent of the drum is not too large, it is processed by supplementing it. The specific approach is: First use gasoline to fill the place, then clean it with acetone, and then use a hard cast iron piled up in the pit, need to be about 0.4mm above the cylinder surface, squeeze 502 glue, dry 2min, After 30 minutes, use a fine-grain trowel to smooth the surface, and then use a 400-gauge sandpaper to smooth. If the indentation is large and deep, use the "Wanda" high-performance structural adhesives of the components A and B of Shanghai Kangda Chemical Plant, adjust the amount of A and B components 11 and immediately add the appropriate amount (about 55%) of iron. Mix thoroughly and fill in the cleaned wells. 10min dry, 60min after the flat, light can be. It should be noted that the proportion of glue should be accurate so as not to be too hard or too soft.
The bumper improvement method: The problem that is easy to bump the bumper. We have improved the bumper. First of all, the original steel bar of φ18mm×n2mm×1080mm is replaced with a copper pipe of φ18mm×0.8mm×l080mm so that its weight is similar to that of the original steel pipe. At the edge of the pressure roller and the transfer roller, the copper pipe was flattened into a plate with a thickness of 0.6 mm, and the roller was not damaged. Change the plastic threaded sleeve at the two ends of the bar to brass (H62) and tightly fit into the bar body. The heads of the screws at both ends were changed to copper heads, which were pressed into a plate with a thickness of 1.2 mm at the ends of the rollers. The rollers were not damaged. The improved bumper has been installed in the equipment and has not failed for one and a half years of use.
Some factories have also achieved good results by adopting this method. Now we are reminding our brother factories that have not taken measures to prevent future problems.