Justification of Technological Conditions for High-Quality Folding and Bonding of Integral Cover Flaps

The object of the study is the processes of folding and gluing of flaps and edges of integral covers within a single technological cycle of their forming. The purpose of the work is to substantiate the technological conditions for ensuring geometric accuracy and reliable bonding of the structural elements of integral covers based on controlling contact interaction in the folding zone. It has been established that the bonding quality is determined by the accuracy of spatial alignment of the elements, which is formed at the folding stage. For quantitative assessment of geometric quality, linear and angular alignment criteria in the form of deviations Δx and Δφ are proposed, and their permissible ranges are substantiated for different quality requirement levels of integral covers. Based on the analysis of experimental observations and geometric generalization of deviations, typical defects of integral covers are systematized, and their cause-and-effect relationship with dominant contact factors in the folding zone is established. It is shown that most defects are caused by peaks of contact stresses, unstable sliding, and violation of the repeatability of bend formation. The folding process is considered from the standpoint of a differential description of contact interaction, which made it possible to substantiate the influence of the geometry of folding plate profiles and the microgeometric condition of their working surfaces on stress distribution, friction, and elastic recovery of the material. It is shown that the use of profiles with a smooth curvature variation combined with controlled formation of a strengthening microrelief on the working surfaces of the plates ensures stabilization of contact conditions, reduction of peak loads, increased repeatability of folding, and compliance with geometric tolerances of bonding. The practical significance of the obtained results lies in the possibility of using the proposed criteria and recommendations for the design and manufacture of folding plates with enhanced geometric stability, which ensures predictable quality of integral covers in mass production.