Two rollers contact each other under the normal load,and when the driving roller rotates,it drives the driven roller rotate by the tangential force on contact area.Finite Element Method analysis and experimental analysis are adopted to research the motion mechanism of two rollers which elasticity has big difference both on the condition of direct contact and indirect contact.From the analysis it is achieved that the relative sliding between the two rollers is due to the tangential force on the contact area and the radial compression deformation of the soft roller which has greater elasticity.For the condition of indirect contact in which a layer of inter-medium exists between the two rollers,the relative sliding is greater than that on the condition of direct contact,and the hardness of the intermedium layer affects the relative sliding between the two rollers.And for the condition of multiple rollers in the state of pressing contact,the number of contact areas on the soft roller also affects its motion characteristics.
In the inking system of an offset printing press,a vibrator roller distributes ink not only in the circumferential direction but also in the axial direction.In the control process,if ink amount is determined only by the dot area coverage without considering the impact of vibrator roller's oscillation,the printing colour quality will be reduced.This paper describes a method of calculating the impact factor of vibrator roller' s oscillation.First,the oscillation performance is analyzed and sample data of impact factor is got.Then,a fuzzy controller used for the calculation of the impact factor is designed,and genetic algorithm is used to optimize membership functions and obtain the fuzzy control rules automatically.This fuzzy controller can be used to calculate impact factors for any printing condition,and the impact factors can be used for ink amount control in printing process and it is important for higher printing colour quality and lowering ink and paper waste.
Ink layer thickness on the printing plate greatly influences uniformity of ink transferred to the substrates,which is an important indicator of printing quality,so the study of ink layer and its thickness is important for improving the quality of printing products. Ansys CFX is used here to build a model of ink fluid adhering to lower vibrator roller,form inking roller,and printing plate for analyzing ink transferring in inking process. Ink layer thickness on each position of the model is acquired to analyze the forming mechanism of ink layer on printing plate,as well as the influence of oscillation speed of lower vibrator roller and dot area percentage of plate on ink layer thickness of printing plate. It can be concluded that,in the case of fixed ink supplying amount,ink layer thickness increases along with the increasing of oscillation speed,and decreases when the dot area percentage is getting larger and the minimum is got when the dot area percentage is 100%. At last,experiment of plate inking on print ability tester verifies the correctness of the simulation analysis.
