Relationship in between compression of the rollers and contact area width and the clamp force
Abstract: In an offset printing machine the rollers (ink unit) and the cylinders (printing unit) are in contact in a lot of places. The contact surfaces comprise a metal surface and a rubber surface. As appears from findings based on the professional literature and experience of people working in printing houses the issue of contact between ink rollers and printing cylinders in an offset printing machine is of great importance. It has impact on the quality of printouts (generation of printouts errors), consumption of energy, time of making the printing machine ready for operation, wear of the machine’s components and related consumables like ink, dampening solution, paper, ink rollers, plate. During the theoretical studies, the equations were derived to show how the rollers compression depends on the contact area width and clamping force. The equations involve Young’s modulus and Poisson’s ratio of rollers’ materials. The difference between these equations and the so far existing equations has resulted from changing the place of applying the clamping force and involving Poisson’s ratio. The paper includes the comparison of the aforesaid new equations and those known from the literature. Moreover, the relationship in between the contact area width and the compression of metal roller and rubber-covered roller was subject to experimental attempts aimed at verification of the equation presented. In order to measure the rollers compression a clock sensor was used, and for measurement of the contact area width – a device called Roller Nip Control. The results of these measurements are presented in this paper and are compared with the results obtained from the equation derived in the course of theoretical studies using the analytical method.
Keywords: contact problem, offset, blanket cylinder, rubber blanket
Area: Mechanics, Automation and Robotics
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