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The structure of finished leather and semi-finished products differ in physical and mechanical parameters. To obtain the properties of elasticity, pliability, and viscosity required in leather production, it is necessary to ensure their values that guarantee the high quality of the resulting product. In this article, a model for finished leather is obtained based on combining the viscoelastic Kelvin model with the deformationinert Khusanov model and the Bingham–Shvedov viscoplastic model. This model makes it possible to improve the elastic-viscous plastic deformation of a fibrous material (leather). The possibility of clarifying the pattern of change in the deformation curve depending on the time the fibrous material is loaded by a certain force was explored. The aim of refining the deformation curve is that in known models, at the initial moment of loading, deformation occurs instantly up to a certain value, which does not fully describe the real physical process of deformation of the material. Consequently, in the proposed refined model, the deformation is fixedat zero value, which provides a real physical pattern of deformation of the fibrous material. The refined model will serve designers of technological machines to develop parameters of deformation during the mechanical processing of elastic-viscous plastic materials.

In this article, the influence of the force pulling the base plate of the vertical shaft machine up along the chain on the pair of compression shafts and the dependence of the moisture squeezed from the semi-finished product being processed on the diameter of the shafts are experimentally studied. The scientific novelty of the research is the development of an improved experimental design of a vertical type shaft machine that flattens the folded areas of wet semi-finished products and compresses excess moisture. The practical significance of the results of the research is explained by the development of an improved vertical type shaft machine for the mechanical processing of the semi-finished products with improved quality indicators of semi-finished products, energy saving, increasing productivity. In experimental studies, a regression equation was developed that determines the amount of excess liquid squeezed out of the semi-finished product during vertical transmission, depending on the diameter of the compression shafts, traction force and transmission speed. Based on the obtained results, graphs were constructed and analyzed. Currently, worldwide attention is being paid to improving the quality of leather products by using energy and resource-saving technologies. As can be seen from the above review, the quality of the processed material is influenced by many parameters of technological machines. Therefore, we believe that an experimental study of the parameters of a vertical roller machine on the properties of the processed leather semi-finished product is relevant.

The effect of varying the number of layers of a semi-finished product, that is, its thickness, and the pressing force between the working rolls on the breakaway force of a multi-layer package of semi-finished products is experimentally investigated in the article. The dependence of the required breakaway force of the working rolls on the change in the number of layers of semi-finished products supplied for mechanical processing between the working rolls at different pressure forces was experimentally determined. The values of the required breakaway force for the working rolls at the established values of the pressing force of the working rolls for packages consisting of five, ten, and sixteen layers of semi-finished products were obtained.

The main parameters of the contact curve of each roll are its shape and length, and the extent of the slip and no-slip zones. Analytical dependencies were obtained that determine the parameters of the contact curves of the rolls of technological machines. It was revealed that at the beginning of the contact zone the skin points are distant from the roll covering point, in the zone at the end of the contact zone it is ahead of it. At the end of the contact zone, the angle between the corresponding points of the skin layer and the roller coating is equal to the modulus of the difference between the lag and advance angles.

Mathematical models of the shape of roll contact curves and patterns of distribution of contact stresses in the roll module of a leather squeezing machine were developed. It was revealed that the shapes of the roll contact curves depend on the deformation and geometric parameters of leather and cloth, as well as the coefficient of friction between leather and rolls. It was established that normal stresses change from zero at the beginning and end of the roll contact zone to a maximum at the point of maximum deformation of leather located in the compression zone; shear stresses change their signs at the neutral point, which in the drive roll is located in the compression zone.

The study is devoted to the analytical description of the residual moisture of leather (semi-finished leather product after dyeing) taking into account the deformation and filtration properties of the semi-finished leather product at this stage. Mathematical models of changes in the removed fluid, hydraulic pressure in the area of leather squeezing, and residual moisture content are determined. The study of the squeezing process based on these models makes it possible to determine with sufficient accuracy the appropriate parameters for roller squeezing of leather, necessary for the rational design and operation of squeezing machines. A condition was established for obtaining minimum residual moisture during roller squeezing, which allows for an increase in the efficiency of roller squeezing of leather.

The conditions for the free flow of the squeezed fluid from a wet semi-finished product along an inclined feed conveyor are studied in the article. The condition of fluid flow against the movement of the feed conveyor is determined. The average rate of fluid flow along the conveyor is determined depending on the thickness of the fluid layer. The dependence of the angle of fluid flow off on the lifting angle and inclination angle of the feed conveyor is determined analytically. The results obtained in the study contribute to the choice of geometric parameters of the transporting device, taking into account its rational lifting angle and inclination angle. Using a numerical method, a graph of the dependence of the angle of the fluid flow along the conveyor on its lifting angle and inclination angle was obtained.

The article examines the movement of semi-finished products in the field of covering with rotating working shafts. As a result of the research, it was determined that in order to improve the quality of processed ore semi-finished products, it is necessary to increase the coverage angle and reduce the radius of the working shafts accordingly. In order to maintain the natural quality of the semi-finished ore product being processed, it is known and justified that if the value of the external pressure force is increased, the radii of the working shafts should also be increased accordingly.

The article presents the results of experimental studies of the process of extracting excess liquid from a water-saturated hide. The experiments were conducted in two options: using a rigid base plate and a cermet base plate for the feed mechanism of the roller machine. In the study, samples of a wet hide on rigid and cermet base plates were pulled between rotating squeezing rollers using conveyor chains. Mathematical dependences of the amount of liquid removed from a wet hide on its feed rate and the pressure of the squeezing rollers were obtained for two special options. The experimental results showed a significant increase in the efficiency of the squeezing process of a wet hide due to the use of a cermet base plate in comparison with a rigid base plate.

The non-homogeneity in mass and geometrical parameters of leather of one type and one manufacturing method is experimentally investigated and analyzed. Experimental studies were conducted on semi-finished cattle products of a combined batch and chrome kips from one technological batch. The results of the experiments showed that with a combined batch, between the mass and thickness of the leather semi-finished product, there is a moderate correlation between the studied physical parameters and the average error of the correlation coefficient of the leather. It is determined that high correlations are expressed between the mass and area of the leather, and between the thickness and area of the leather, respectively. It was revealed that the samples of leathers selected for experiments (kips), depending on their type, weight and area, have a higher correlation. So, between the mass, thickness and area at the standard point of the kip, there is a higher correlation between the studied physical parameters of the semi-finished leather samples. The results obtained provide an opportunity to influence the properties of leather for further creation of methods of controlling the relevant devices and equipment at various stages of production processes.

The conditions for the vertical pulling of a semi-finished leather product laid bent on a transporting base plate between rotating squeezing rollers are theoretically investigated in the article for the first time. At that, an important role is played by the value of the radii of the squeezing rollers, installed in one row in the horizontal plane, and the value of the corner radius of the front part of the transporting base plate. If the value of the corner radius and the thickness of the base plate are large, then when it contacts the squeezing rollers, a significant frontal resistance arises. Thus, to derive the conditions for gripping the semi-finished leather product between the rotating squeezing rollers, the pulling-in force of the traction chains, the normal pressure force of the squeezing rollers, the coefficient of friction between the rotating squeezing rollers and the leather semifinished product are taken into account. The condition for the vertical pulling of the semi-finished leather product laid on the base plate is determined, taking into account the coefficient of friction between the semi-finished leather product and the squeezing rollers when they come into contact.

The article presents the results of experimental studies to substantiate the performance of the method of simultaneous extracting excess moisture from wet leather semi-finished products. In the experiment, the influence of the feeding speed, the pressing force of the squeezing rollers on the amount of moisture removed from two layers of the leather semi-finished product after their squeezing was determined. The experiment was conducted using a moisture-removing material - a BM brand monchon, laid on a guide bar, on which two layers of the wet leather semi-finished product were previously folded. A monchon of the LASCH brand is folded between the layers of a semi-finished leather product. Due to the flexibility of the monchon, the displacement of semi-finished leather products movement path along the conveying device is reduced.

The paper provides fluid receding from moisture cloth in taking account geometry of contact zone, it is considering the moving between rotating rollers, when rollers have equal radiuses. It's defined location of the cloth element statement center with taking into account changes of pores and fluid capacities in element of cloth. [ABSTRACT FROM AUTHOR]