Hidden troubles and improvement of bumper of the h

2022-08-14
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Hidden troubles and improvement of bumper of Heidelberg five color offset press

the printing factory introduced an electronic tensile testing machine fixture as an important part of the instrument in 1992, Heidelberg 102f five color offset press in Germany. The machine has advanced performance and good quality, but there are also some problems in use, which affect the safety of the equipment and the printing quality, the most prominent of which is the bumper problem that affects the safety of the equipment. I am engaged in the installation and use of this machine. Now I will talk about my personal views on the causes of the problems and the experience of improvement for the reference of my peers

in 1994, a brother factory in Liuzhou introduced a five-color offset press at the same time, in which a group of bumpers fell off and pressed into the drum during the operation of the equipment, resulting in indentation of the pressure drum, serious decline in accuracy and can not be used, and repair requires huge money and time, so only four of them can be used

1 all the testing machines have those responsible errors. In 1995, similar accidents occurred to the machines in our factory. The bumper fell off between the pressure roller and the paper delivery roller. Although the machine was stopped in time, the bumper was still pressed in 2/3, leaving a 10mm 3mm 1.5mm dent on the right side of the cylinder. The toothing rod of the pressure roller was deformed, 7 teeth seats were cracked to varying degrees, and 5 teeth were damaged. It took us a lot of effort to take out the scrapped bumper. Check the accuracy of each drum, and it is basically unaffected today. After repairing the obviously damaged accessories, continue to use, and gradually find inaccurate overprint or instability. After expert consultation, it was found that the handover angle was affected and changed

after analysis, the cause of the accident is that the internal thread plastic sleeve clamped at both ends of the safety shoulder is aged and broken, resulting in the loss of support and falling off of the bar body, which is pressed and pushed into the next clamping installation between the rollers, resulting in the indentation and accuracy reduction of the barrel. The bar body is a 18mm 1080mm copper pipe, with a double-layer wall thickness of 4mm. After extrusion, it becomes 2.8mm. It can be seen that the roller bears a great pressure load. At the same time, the plug at both ends of the bar, which is a hard steel piece, causes indentation and accuracy damage. The plug is an M10 hexagon screw. According to the analysis of the scars on the surface of the embossing cylinder, the plug is the root cause of the 10mm 3mm l.5mm dent in the cylinder and the damage of the tooth seat, tooth shaft and tooth, as well as the change of the cylinder joint angle

treatment method: since the dent of the drum is not too large, the method of filling is adopted. The specific method is as follows: first clean the place to be leveled with gasoline, then wipe it with acetone, and then stack it in the recess with hard cast iron, which needs to be about 0.4mm higher than the cylinder surface, squeeze 502 glue, dry it in 2min, file it with a fine grain file after 30min, and polish it with 400 sandpaper. If the indentation is large and deep, use Wanda high-performance structural adhesive of components a and B of Shanghai Kangda chemical plant, adjust it according to component 11 of components a and B, immediately add an appropriate amount (about 55%) of iron powder, mix it well, and fill the cleaned recess. Dry in 10min, file and polish in 60min. It should be noted that the proportion of glue should be accurate to avoid being too hard or too soft

improvement method of bumper: Aiming at the problems prone to occur in the bumper, we have improved the bumper. First, the original 18mm n2mm 1080mm steel pipe of the bar body is changed into 18mm 0.8mm l080mm copper pipe, so that its weight is similar to the original steel pipe. At the edge of the pressure roller and the paper delivery roller, the copper tube is flattened into a plate with a thickness of 0.6mm, and the roller is free of damage. Change the plastic internal thread sleeve at both ends of the bar body into brass (H62) and fit it tightly into the bar body. The screw heads at both ends are changed into red copper heads, which are pressed into a plate shape with a thickness of 1.2mm at the edge of the drum, and the drum is not damaged. The improved bumper has been installed in the equipment and has not failed since it was used for one and a half years

some factories have also achieved good results by adopting this method. Now we remind brother factories that have not taken measures to prevent future troubles

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