Abstract
This work aims to improve the technology and equipment for forming shoe upper blanks on a last. One of the significant drawbacks of forming shoe uppers using the covering tightening method on ZNK-type machines is the uneven distribution of deformations across the toe-tuft portion of the upper blank. Specifically, the vamp exhibits the greatest transverse deformations along the contours of the forming surface of the last in its peripheral areas, where the elongation of the blank is greatest and can exceed the deformation values in the central part of the vamp by 3-4 times or more. Furthermore, the blank exhibits the greatest average (over the vamp width) transverse elongations in the toe area, which also decreases several times as it approaches the tufts. The existing uneven distribution of elongation across the upper blank area during the covering- tightening forming method results in the leather's valuable properties not being fully utilized in areas of the upper blank with insufficient stretch. This article is based on the authors' research into developing new methods and improving devices for stretch-stretch operations in footwear production. To more evenly distribute deformations across the toe-tuft portion of the upper blank, an improved insole stop design is proposed, providing additional stretching of the vamp in the tuft zone. Uniform stretching of the upper blank along the contours of the forming surface of the last (punch) is achieved through new methods of uneven heating of the blank and uneven moistening of the forepart of the upper blank. The aim of this study is to improve the dimensional stability of manufactured footwear and reduce the consumption of upper leather by using scientifically substantiated dimensions of the initial blank area, taking into account rational deformation, the configuration of the enveloping contour of the forming surface of the shoe last (punch), etc. This study was conducted using a computational and analytical method based on advanced methods and equipment for implementing the technological process of forming shoe upper blanks on a last (punch). The results of this study will improve the quality of manufactured footwear, reduce their cost through scientifically substantiated design of rational dimensions and area of the initial upper blank, and improve the equipment for forming shoe upper blanks on a last.