Journal of Machinery Manufacture and Reliability最新文献

This paper is devoted to the important problem of increase in the wear resistance of a radial bearing that operates in the hydrodynamic mode due to applying an antifriction polymer composite coating with an axial groove, which has truly viscous properties, on a nonstandard bearing bush adapted to friction conditions. The dependence of the rheological properties of a lubricant under turbulent friction on the pressure and temperature is considered. As a result, the velocity and pressure fields in the axial groove and on the surface of the polymer antifriction composite coating have been determined, as have the load capacity and friction force, which make it possible to increase the load capacity, reduce the friction coefficient (increase the wear resistance), and also increase the duration of the hydrodynamic mode. The results of numerical analysis of theoretical models and experimental study of the suggested design are presented to verify and confirm the effectiveness of the models obtained.

The operation of the executive bodies of soil and soil-cultivating equipment (for example, the teeth of excavator buckets) is often accompanied by the formation and development of local wear, which is the cause of destruction. Meanwhile, well-known theoretical studies devoted to the study of working conditions and forecasting the resource of such parts are few and are of a private nature, stipulated by the solution of specific problems. This article deals with cantilever-fixed parts in the case of prevailing wear in local areas of the working surface. A rectangular cantilever fixed beam subjected to bending with a section where a groove simulating wear is located is considered as a calculation model. It has been established that the working state of a cantilever-fixed part with the presence of local wear is determined by a system of inequalities relating its geometry to the allowable stresses and pressure of the wear medium. A mathematical model has been obtained facilitating prediction of the resource of a part as its wear develops.

Based on the principles of elasticity theory, an assessment of the adhesion for bodies stuck together has been carried out by the example of a “particle of sprayed powder–metal substrate.” Relationships for determining the shear stresses and separation stresses are obtained. The comparison of the theoretical values of shear stresses and separation stresses with experimental data confirms the validity of using adhesion theory for calculation of the adhesion strength for coatings obtained by means of thermal spraying. The developed theoretical principles make it possible to choose a suitable fraction of the deposited powder material, which can provide the required strength of adhesion between the main coating layer and the metal substrate or sublayer in the course of thermal spraying.

The analysis and relevance of the application of innovative technological processes in the treatment of gas turbine engine blades is considered. The technological processes of producing such blades play a decisive role in providing the reliability, performance, service life, and operation time of gas turbine engines in general. An analysis of the technological processes making it possible to increase the productivity and quality of machined blades is presented. The advantages and disadvantages of some technologies have been compared. Particular attention is paid to the technological processes of restoring worn blades for gas turbine engines. The development of intelligent process control systems in manufacturing gas turbine engine blades is one of the main directions for improving technological processes at the present time.

High-density silicon carbide ceramic materials with enhanced physical and mechanical characteristics are obtained by selecting the particle size of the furnace charge and reactive sintering (siliciding). Various mechanical properties of silicon carbide materials are analyzed depending on the content of the core silicon carbide fiber.

This article discusses the issues for ensuring high technical and economic indicators of automated technological complexes through simulation modeling and optimization of workpiece maintenance discipline. An example of simulation modeling of a flexible automated production site for a group of parts of the housing type in the AnyLogic software environment is given. As a result of simulation modeling, regression dependencies were obtained that made it possible to determine the optimal parameters for the workpiece maintenance discipline, ensuring a minimum volume of work in progress. At the same time, boundary conditions were taken into account: load factors of equipment and industrial robots, as well as the productivity of automated technological systems (complexes).

The experimental results of the influence of an elastic vibration limiter on the dynamics of a prototype of a vibrating machine with self-synchronizing unbalanced vibration exciters when excited in the resonant frequency range are presented. The prototype is made according to the scheme of a single-mass vibration machine with plane oscillations of the working body (platform), which are excited by two unbalanced asynchronous vibration exciters. The vibration amplitudes of the platform and the mutual phase of rotation of the vibration exciters as a function of excitation frequency were obtained for various weights of the loads installed on the platform. It is shown that contact with an elastic limiter leads to an expansion of the frequency range in which synchronous rotation of vibration exciters with the required mutual phase is ensured, as well as to a decrease in the resonant frequency ranges of the sensitivity of the vibration amplitudes of the platform to changes in the weight of the system. The results confirm the previous results of theoretical analysis.

The existing technologies for production of elastic goods using 3D printing are discussed. The drawbacks and limitations of the known 3D printing technologies in the production of elastic goods are considered. A novel 3D printing technology is suggested for the production of silicon and polyurethane elastic items; the prospects of its application and development are given, as are examples of the products obtained.

In the system of maintenance and repair of machines, many elements are regulated by standards and technical conditions. Establishing a correspondence between the reliability of restored parts and connections with the reliability of machines is of scientific and practical interest. The economic feasibility of restoring parts is usually assessed by comparing the cost of a new part and the cost of repairing a worn one.

This article provides and considers an analysis of technologies aimed at forming shaped regular surface textures.