Journal of Machinery Manufacture and Reliability最新文献

Various types of expansion joints are used to compensate for thermal and force movements of equipment and pipelines. At gas pumping stations and power plants and in transport, expansion joints simultaneously provide vibration isolation of equipment from pipelines, foundations, and the environment. Reduction of vibration and noise transmission is necessary in the frequency range from infrasound to a thousand hertz or more. This article considers the features of thin, elastic rubber–metal elements proposed by the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) as elastic elements for a new type of expansion joint that improved vibration pipeline isolation by two orders of magnitude compared to commercially available expansion joints in the frequency range up to 1600 Hz. The article shows the feasibility of further improving the operational and vibration-insulating properties of expansion joints with thin rubber–metal elements due to the design and changes in the formulations of rubber, adhesives, and reinforcement material of expansion joints.

The article addresses the issue of selecting the optimal composition and production technology for the charge used in sealing rings of gas engine compressors. These rings are made from a composite based on fluoropolymer F-40 with the addition of graphite and copper-plated graphite. It is demonstrated that the properties of the resulting material depend significantly on the dispersion of the fluoropolymer particles. The study proves that heterogeneity caused by manual or mechanical mixing leads to a sharp decrease in material strength as the graphite content increases. It is established that the highest compressive strength of the composite material is achieved when the fluoropolymer particle size is within the range of 50–150 μm and the components are mixed uniformly. Furthermore, as counterpressure and surface cleanliness increase, the friction coefficient of all tested materials initially reaches a minimum and then gradually begins to rise.

A scientific and methodological approach to the construction of professional risk management (PRM) models during the construction of facilities for the oil and gas chemical industry from the standpoint of human–machine (ergatic) systems, which are considered as generalized models of organizational and technical structures of various management levels, is described. Occupational safety in such systems is based on the identification of hazards, assessment and management of risks caused by a set of parameters of the working environment and work process, and the influence of the human factor. A conceptual expert system developed by PJSC Gazprom Neft for assessing the level of funding for professional risk management activities was developed, which took into account the provision of material motivation of contractors fulfilling contractual obligations in the field of industrial and environmental safety, labor protection, and civil defense.

The possibility of using deep neural network models, in particular the U-Net architecture, for automated detection of the profile of a worn part is examined. Wear of working elements, especially in agricultural machinery, sharply reduces the efficiency of the equipment and increases the costs of its maintenance. Traditional diagnostic methods have a number of limitations, including subjectivity of assessments, the need to stop equipment, and the low accuracy of quantitative assessment of wear. A method of semantic segmentation of images using the U-Net neural network is proposed, which allows for the automatic formation of a profile of a worn part. The stages of data preparation, model training, and image analysis are described, which ensures accurate obtaining of the part profile. The effectiveness of the method was confirmed experimentally using a deep-ripping chisel as an example.

The methodology of stochastic modeling of industrial networks based on GERT networks, which eliminates the limitations of classical PERT and CPM methods by taking into account probabilistic operations, alternative paths, and feedback is discussed. A mathematical apparatus has been developed that combines graph and probability theory, as well as a modified Monte Carlo algorithm for analyzing time parameters. The Python implementation includes simulation, 3D visualization, and IoT integration. Practical tests have confirmed an increase in resource efficiency by 15–20%. The research prospects are related to the integration of GERT networks and AI to create digital twins. The results are relevant for specialists in the field of industrial engineering and management of complex systems.

An analytical model for calculating the temperature under dry external friction in conditions of longitudinal rolling (passage through one stand) of a thin strip is presented. Graphs of the calculated temperature dependences on the speed, rolling, time, and depth for a 12X18H9T steel strip are given.

The process of metal layer deposition on a horizontal surface of a steel plate up to 5 mm thick using a bulk material in the form of an aluminothermic charge is studied. A mathematical model is constructed using the Prandtl–Reuss model as an example, in which Hooke’s law is replaced by the Duhamel–Neumann law, and the von Mises condition takes into account the properties of a viscous metal. The elastic moduli and yield strength are assumed to be temperature-dependent. The calorific value of the aluminothermic, which affects the process of metal deposition and slag crust formation, is calculated. The ratios of the width and height of the charge layer are determined using the example of a plate made of cold-resistant steel 20A, the use of which will guarantee the melting of the metal surface without the formation of a through burn.

The electroplastic effect during tension and rolling was investigated in a high-strength overstoichiometric coarse-grained alloy based on the TiNi intermetallic compound. A comparison of deformability during cold flat rolling with and without a pulsed electric current was also conducted. It was shown that the increase in deformability under a current during rolling is mainly associated with the athermal electroplastic effect.

The results of working surface heating simulation during friction stir welding (FSW) are presented. The thermal cycles of tool shoulder and working surface contact points are plotted. The effect of friction coefficient, tool rotational velocity and preheating temperature on the process of welding heating is examined. Probability of the liquid lubricant film formation at the moment of FSW process starting is evaluated.

Working machines play an important role in modern industrial production. In this regard, the analysis and synthesis of generalized structural schemes of machines play a fundamental role. Currently, the main focus is on the synthesis of structural and kinematic schemes of mechanisms, while the issues of rational selection of the structural schemes of machines receive less attention, although it is precisely the study of generalized machine schemes at higher hierarchical levels that can yield significant benefits. This article addresses the issues of analysis and synthesis of generalized structural schemes of working technological machines based on a morphological approach. Using a set of machines for additive technologies as an example, various sets of technical solutions are considered, up to the examination of individual schemes. In conclusion, the prospects of using the morphological approach for the chosen topic are discussed.