Journal of Machinery Manufacture and Reliability最新文献

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.

This study is devoted to the development of a mathematical model of the rolling friction process of elastic bodies. It is shown that rolling friction has a dual character, since it depends on the microslip forces of the contacting surfaces and on the adhesion forces on the contact surface. The influence of adhesion forces on rolling resistance prevails in cases where the line of contact of bodies is close to a straight line, for example, when a roller rolls on a plane or when two identical balls roll, and the forces caused by microslippage of surfaces prevail with a curved line of contact, for example, when a ball rolls on a narrow groove. The results of modeling are compared with the results of experimental studies previously carried out by Pinegin, who confirmed the adequacy of the mathematical model.

The tribotechnical properties of alcohol–water lubricating compositions are investigated. The use of alcohol–water lubricating oils represents a promising direction for enhancing environmental friendliness and improving reliability in mechanical engineering. The tribotechnical properties of the lubricating compositions were studied, including friction coefficients, changes in the width of the friction track, changes in the wear spot area, and the dependence of temperature increase over time. The research results show that aqueous lubricating compositions can provide acceptable tribotechnical parameters comparable to those of traditional petroleum-based lubricants, confirming their competitiveness in the market. Thus, the main focus of this study reflects important aspects of combining the efficiency of lubricating materials with environmental safety and stimulates further scientific research and practical developments in this field.

The issues of development and study of new highly efficient porous molybdenum powder friction coatings for operation in oil with an increased friction coefficient and wear resistance, obtained by plasma spraying, with respect to gearbox synchronizer cones as well as friction and brake unit disks are considered. The characteristics of the developed porous powder molybdenum friction coatings and the technological parameters of their production for friction devices of tracked vehicle transmissions with high specific power are presented.

A method for force analysis of a precessing gearbox is presented. A design is shown that is not inferior to known promising analogues. The development is based on internal bevel gearing, characterized by high quality indicators. It is noted that the precessing gearbox can be widely used as a step-down gear in various equipment.

This article is devoted to the study of the most important parameters of coatings formed by the high velocity oxygen fuel process. The surface microgeometry, the structure of internal regions, and the transition zone between the coating and the substrate, as well as the microhardness, largely determine the main physical characteristics of the applied coatings. It is shown that the microstructure and microhardness of coatings formed by the high velocity oxygen fuel process depend on the compositions of the powder materials and the application modes. It was established that when forming coatings from the WC–Co–Cr 86–10–4 powder material, their maximum microhardness is about 1475 HV; when using the PR Kh14N7S3R3 powder, it is 927 HV; and when spraying the experimental WC–Co–Cr 64–23–10 powder, it is approximately 1154 HV.

Diagnostic criteria applicable for the implementation of digital thermal diagnostics technology for bearing units are proposed. The temperature state of the bearing units of the truck rear axle, typical for normal operating modes, is studied. The possibility of using automatic temperature diagnostics of the studied bearing units is confirmed.