Research On The Influence Of Contact State Between Flexographic Plate And Substrate On Printing Quality

In the process of flexographic printing,appropriate printing pressure is required to obtain high-quality post-press products.To determine the appropriate printing pressure,multiple factors need to be considered.During the pressing process,the flexplate will deform,and the ink between the flexplate and the substrate will be completely squeezed out under excessive printing pressure,resulting in poor contact and insufficient ink transfer rate when the printing pressure is low.The purpose of this thesis is to explore the process of squeezing the printing plate cylinder by the imprinting cylinder,as well as the contact state and deformation between the flexible plate and the substrate.By establishing the contact mechanics model of the plate cylinder and the impression cylinder,the influence of the combined pressure on the deformation of the substrate,flexo plate and plate mounting tape was analyzed.And through calculation examples,it was found that during the printing process,the adhesive tape for plate mounting suffered significant deformation,while the deformation of the flexible plate was relatively small.Through a flexible plate roughness measuring instrument,it was found that both the surface of the flexible plate and the substrate have roughness,and roughness can have a significant impact on printing quality.Through mechanical modeling,the deformation of the surface roughness of the flexible plate under different pressure levels was calculated.It was found that under larger pressure levels,the roughness of the surface image and text of the flexible plate would be squeezed and flattened,causing more ink to accumulate towards both ends of the line.If the printing pressure is small,Causing insufficient contact between ink and substrate on the flexographic plate,affecting ink transfer.In order to analyze the impact of superelasticity of flexographic plates and adhesive tapes on printing quality,compression tests were conducted on the flexographic plates and adhesive tapes.The flexographic plates were represented by the Mooney Rivlin model and the adhesive tapes were represented by the Yeoh model.And using the finite element method,the influence of superelasticity on the variation of line width was analyzed.It was found that the variation of line width in the superelasticity model was significantly greater than that in the linear model.By correcting the surface roughness deformation,compared with the linear model,it was found that in actual printing,a smaller pressing amount would cause the roughness to be squeezed flat,and the ink would accumulate towards both ends.Finally,through flexographic printing experiments,it was shown that the trend of the experimental results is consistent with the calculation and simulation results of the hyperelastic theoretical model,and under high printing pressure,it is obvious that there is a blank part in the middle of the line.Under low printing pressure,the ink transfer effect is poor.