J2108, J2203 old offset press pressure

In printing, the printing pressure is very important, if the pressure is not adjusted properly, it is difficult to print the perfect product. The service life of the offset press has been long, and the shoulder iron of the printing cylinder has been corroded by the potion, and the wear between them has become a benchmark for printing pressure adjustment. So how do you properly adjust the printing pressure between them and make the pressure between them similar to the new factory machine?

Our thoughts and practices are as follows: The pressure cannot be adjusted based on the shoulder roller of the tick roller. The adjustment should be based on the working surface of the printing roller. As long as the distance between the rollers after the printing cylinder is pressed is determined, and the feeler is used to adjust, the desired printing pressure can also be obtained.

From the manuals of the J2108 and J2203 offset presses, it is not difficult to know the diameter of each roller. As shown in the figure, the shoulder diameter of the plate cylinder is φA=299.8 mm, the shoulder radius of the blanket cylinder is φB=300 mm, and the shoulder iron diameter of the impression cylinder is φc=299.5 mm. The diameter of the working surface of the plate cylinder is φ1 = 299mm, the diameter of the working surface of the blanket cylinder is φ2 = 293.5mm, and the diameter of the working surface of the impression cylinder φ3 = 300mm. It is also known that the gap between the drums of such machines is CA=CB=0.2mm after the pressurization. The center distance between the plate cylinder and the blanket cylinder after pressing can be determined as F1=1/2(φA+φB)+CA+1/2(299.8+300)+0.2+300.1(mm). The center distance after the blanket cylinder and the impression cylinder are pressed is F2=1/2(φB+φC)+CB=1/2(300+299.5)+0.2=299.95(mm). Then, the gap between the platen and the blanket cylinder after the pressure is pressed can be determined as the gap M1=F1-1/2(φ1+φ2)=300.1-1/2(299+293.5)=3.85(mm). The gap between the blanket cylinder and the impression cylinder after the pressure is pressed is M2=F2-1/2(φ2+φ3)=299.95-1/2(293.5+300)=3.2(mm).

Through the above calculations, the pressure gap of the working surface of each roller has been known. When the pressure is adjusted, the rubber and the printing plate are removed, the working surface is cleaned, and the feeler is used to measure the pressure between the impression roller and the rubber roller. , Adjusted to the pressure gap is M2 = 3.2 mm; then between the blanket cylinder and the printing plate face, adjust the pressure gap to M1 = 3.85mm. After adjusting the pressure, the lining of each roller is the same as the original one. The pressure adjusted by this method is more accurate, and it can also print quality products.