Schemes and methods of manufacturing parts such as disks from square blanks obtained by stamping are studied. The possibility of controlling boundary conditions, creating various schemes of stress-strain state in local zones, changing the nature of metal flow, providing relatively low levels of residual stresses and anisotropy of mechanical properties in the longitudinal and transverse directions, allowing to stamp rolling workpieces. It is shown that in the technological process of stamping by running-in of annular workpieces of parts from a square workpiece, a metal displacer passes in different axial directions of the workpiece through three stages of forming. Deformation resistance throughout the volume of the part is also different. As a result, there are additional stresses: on the outer surface - compressive, as each inner layer restrains the movement of the neighboring outer, and in the inner - stretching, as each outer layer, moving faster than the neighboring, captures it. The device of manufacturing of details of type of disks from square preparations is offered in work. The principle of operation of this device is that the original workpiece with a square cross section before installation in the matrix is pre-fixed relative to its angles. As a result of stress equalization, there is a zone of inner layers with additional radial stress, which increases to the outer. The use of the device proposed in the work makes it possible to stamp parts without waste, to expand the range of products obtained, as well as to reduce the cost of manufacturing the product by facilitating the flow of metal. The calculation formula for determining the size of the original square workpiece is proposed. The choice of the sizes of initial preparations according to the calculation formula simplifies their preparation by felling, facilitates centering at stacking in a stamp, and the main thing provides high accuracy of the size on height and absence of anisotropy unlike the circles cut out from a sheet.
The reliability of automotive internal combustion engines is a function of the reliability of their mechanisms and systems. For many years, domestic and foreign engineers have tested many auto-tractor internal combustion engines and it has been proven that if mathematical models reliably describe physical phenomena, cycles or processes that take place in engines, then the theory of small deviations for theoretical research is much better than any experiment on control characteristics and many second parameters The theory of small deviations for fuel equipment of autotractor diesel engines is considered in the article. The method of transition from the ordinary differential equations describing the quality of diesel fuel spraying to the equations in small deviations. Equation of kinematics and hydrodynamics of precision pairs of fuel equipment in small deviations. Consumption characteristics of fuel in the process of injection in small deviations. Methods of similarity, dimension theory, mathematical statistics, and probability theory, which are used in determining the resource and predicting the operation of tractor engines. It is shown that the most practically accepted method for determining the residual life of autotractor engines is the method of mathematical statistics and probability theory. The role of mathematical modeling in determining the residual life of fuel equipment of autotractor diesel engines is established. It is also noted that it is advisable to use the small deviation method to accurately describe the processes in the fuel equipment of autotractor diesel engines. The mathematical model is based on the known physical laws that describe the interdependencies of the two groups of parameters, control and operational, both within and between groups. The transition of the classical differential equations describing the processes of fuel supply and injection, taking into account fuel leaks in precision pairs, into equations with small deviations of parameters, is shown. The relationship between injection, fuel supply and fuel leakage is analyzed and the most influential parameters found. Impact coefficients are found and their dependencies are plotted on their corresponding parameters. Using the obtained dependencies, the influence of the technical condition of precision pairs on the effective performance of the engine is characterized. Dependences of change of injection characteristics on small deviations of parameters characterizing the technical condition of precision pairs of fuel equipment are also established.
On the basis of the engineering practices of the last 3-4 decades, it is known, tested and proven that, while mathematical models provide reliable descriptions of processes, cycles or physical phenomena, in theoretical research the theory of small deviations is comprehensively preferable to any experiment on regulating characteristics. Considering the fact that all parameters and characteristics are sometimes interconnected by nonlinear dependences, it is impossible to distinguish the influence of a specific parameter on the sought-for value, and can be even hazardous if the determinant argument or its derivative has extreme values. The role of mathematic simulation to determine the residual lifetime of the fuel injection equipment of diesel engines was established. It was also noted that for a reliable description of the processes going on in the fuel injection equipment it is advisable to use the method of small deviations. The mathematical model is based on the known physical laws that describe the interdependence of the two groups of parameters: engine variables and performance parameters - both within the groups and between them. The transition of classical differential equations describing the processes of fuel supply and injection taking into account fuel leaks in precision pairs to the equations with small deviations of parameters is shown. An analysis of correlations between the parameters of injection, fuel supply and fuel leakage was carried out and the most influential parameters were found. The influence coefficients are found and correlations between the influence coefficients and the corresponding parameters are constructed. We used the correlations found to describe the influence of the technical condition of precision pairs on the engine performance indicators. The correlations between the change in injection patterns and small deviations of the parameters describing technical condition of precision pairs are also established.
A technological passport of the alloy steel material has been formed, from which a piston-connecting rod pair of an axial-rotor piston pump is made in the form of functions: flow curve, plasticity diagram, Bauschinger curve, calibration graph. Using the approximation of the neck contour by the Gaussian function at any moment of deformation of a cylindrical specimen in the supercritical region, the main parameters used in engineering calculations are related: the minimum diameter of the specimen, the current diameter of the specimen with a given coordinate, the relative (absolute) elongation and contraction with the parameters referred to the moment of rupture sample. In addition, the elongation and contraction of the sample after fracture are unambiguously associated. The approximation avoids the inconvenient and relatively expensive video filming for studying the history of deformation. It is shown that the effect of heat treatment on the mechanical properties of these steels is not the same for different stress state schemes. The tensile strengths of these steels are close as delivered. The plasticity characteristics of steel 30Kh3MFA exceed the plasticity of steel 38Kh2MYuA by 1.5 times. The flow curves of the steels under consideration have the following tendency: so the coefficient of approximation of the flow curve for 38Kh2MYuA steel in the delivery state exceeds its value in relation to steel 30Kh3MFA by 1.23 times. After heat treatment of these steels, the value of the approximation coefficient increases: for steel 38Kh2MYuA by 1.11 times, for steel 30Kh3MFA by 1.46 times. The results obtained make it possible to control the mechanics of the technological operation of rolling the piston-connecting rod pair and create a process control mechanism in order to prevent rejects during the rolling process, which manifests itself in the form of going beyond the tolerance field for the axial clearance of the piston-connecting rod pair, as well as destruction during rolling of the inner part of the piston.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.