The dissertation was performed at the Department of Machines and Units of Printing Production of the Publishing and Printing Institute of the National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, under the guidance of Doctor of Technical Sciences, Professor Kirichko P.A.
The work is the result of independent research by Shostachuk O.P., provided by the chosen topic. In the course of research, the author for the first time substantiated and developed a method for determining the stiffness of the printing apparatus, namely the deformation of printing and forming cylinders, investigated the physical and mechanical properties of corrugated cardboard and flexographic forms. Theoretical developments of technological process of printing on sheet flexographic machines are analyzed and generalized, the factors influencing printing process and quality of printed production are defined, the analysis of interrelation between properties and parameters of components of technological process and quality of passing of printing process during which can arise various defects.
The printing equipment, its specifics and features are analyzed and presented. The main components of flexographic printing machines for corrugated cardboard were identified and systematized, and on the basis of the obtained data a method was chosen for further analysis of the designs of sheet flexographic equipment. The technical and operational properties characterized by the suitability of printing equipment for its effective use, determination of its technical condition, efficient operation with the approved system of maintenance and repairs are considered.
Analyzing the factors influencing the quality of printing, it was determined that the rigidity of the printing apparatus is one of the most important characteristics. The deflection of the cylinders leads to the need to increase the pressure on the elastic flexographic printing plate to ensure its working deformation. This causes a deterioration in print quality and the appearance of such defects as compression, blurred contours, deformation of corrugated cardboard.
To determine the deflection of the geometric axis of the cylinder, a formula was calculated that allows the most accurate determination of deflections in an analytical way. Also typical defects as the press on a corrugated cardboard has many features which are caused by conformity of requirements to quality and components of technological process, and also a design and a technical condition of the printing device. Researches in the conditions of production process on test forms with special elements are carried out.
Experimental studies of the physical and mechanical properties of corrugated cardboard and flexographic printing plates in the process of printing on sheet flexographic machines were carried out. The essence of the method is to apply a destructive force during compression. Tables of values were compiled for each sample, which allowed to qualitatively and quantitatively assess the deformations, the factors influencing their physical and mechanical properties under planar compression were determined, indicators, dependences of deformation values on applied loads were investigated. To control the quality of flexographic products, the influence of environmental parameters (humidity, temperature, static load, etc.), the printing process itself and the technical condition of the printing apparatus is systematized.
A step-by-step scheme of deformation of corrugated cardboard and flexoforms depending on pressure is developed, which allows to determine the maximum pressure values for different types of corrugated cardboard and flexographic forms. According to the results of the research, corrugated cardboard is classified depending on its construction.
