Talk about the length of the print in front and in the direction of the print is not consistent with the film

In the case of ignoring paper deformation, when the plate cylinder diameter (printing plate and liner thickness) is equal to the impression cylinder diameter (plus paper thickness), the size of the imprint on the plate is equal to the size of the imprint on the paper. For Heidelberg presses, the diameter of the plate cylinder liner is generally fixed (sometimes 0.30 mm thickness is used) so that when the thickness of the printing paper changes, the print size in the front and rear direction of the print will be Changes occur when the impression cylinder diameter (plus paper thickness) is different from the plate cylinder diameter (printing plate and lining). The print on the print will deviate from the length of the print on the plate.

Plate cylinder and impression cylinder rely on gear transmission, so in the printing area, the rotation angle of the two rollers is always equal, if Ri>Rp (Ri: radius of impression cylinder after adding paper; Rp: radius of plate cylinder), The length of the print on the paper is greater than the length of the print on the plate; if Ri

Therefore, when changing the thickness of the paper, the print on the print cannot completely be required to completely coincide with the print on the plate (on the film).