Determination of the actual deckle contact area and the actual pressure in the printed area

Abstract

The article determines the effect of micro-roughening of the surface roughness of the printing plate on the deformation of the deck. To study the effect of printing plate surface roughness on the actual contact area of the deck in the printing area, the interaction of the roughness microroughness with the surface of the softer material of the deck was considered. A review and discussion of the results of studies on contact problems was made. To determine the actual contact area from the applied load, the distribution of micro protrusions of the surface roughness of the printing plate is taken into account. A method has been developed for calculating the actual deckle contact area and the actual pressure in the printing area, taking into account the surface roughness of the printing plate. According to the proposed method, the values of the actual deckle contact area and the actual pressure in the printing zone were calculated. It has been established that with an increase in the normal load, the actual deckle contact area increases. Also, an increase in the normal load leads to an increase in the actual pressure. The set values of the actual contact area and the actual pressure contribute to the formation of an elastic saturated contact of the deckle, which ensures high quality prints. The results obtained by the developed method are compared with calculations based on known dependencies. In calculations, the number of protrusions crossed by the average level and the number of protrusion tops located above the midline in the area corresponding to the base length are determined, respectively, by the average roughness step and by the average step between adjacent roughness protrusions. The research results make it possible to make the right choice of printing plates and decals when adjusting and operating a printing machine, as well as to set the actual pressure value, which ensures high quality prints.

Development of a scheme for the distribution of contact areas between the plate and offset cylinders

“…The distortion of the image caused by the deformation of the platen press depends on the load during printing [3][4][5]. For this purpose, new methods for estimating the real contact area depending on the normal load are presented [2,[6][7][8][9][10][11]. Mutual contact of parts occurs along the roughness peaks and ledges, on which real contact is made [12,13].…”