Journal of Machinery Manufacture and Reliability最新文献

The nonisothermal elastohydrodynamic problem for an oil film journal bearing is considered. The mathematical bearing model is presented. A method for joint numerical solution of nonisothermal lubrication equations and contact deformation equations is presented. The results of numerical calculations are compared with known experimental data on the minimum thickness of the lubricating layer and the maximum temperature in the lubricating layer.

The results of a feasibility study on the effectiveness of using various flange lubricators are presented using the example of equipping VL-80 electric locomotives with contact and liquid flange lubrication. The effect-forming factors obtained during the use of flange lubricators and the distribution of effects between the Traction Directorate and the Service Company that provides servicing of locomotives with installed flange lubricators are determined. A comparative analysis of two scenarios is performed, using contact and liquid type flange lubricators and a comparison of the main indicators determining their technical and economic efficiency.

The vibrations of a three-section boom of a concrete pump in the vertical plane on a three-mass dynamic system are considered separately from the torsional vibrations of the boom and its vibrations in the horizontal plane. The differential equations are based on the generalized Hooke law. The values of the periods of natural oscillations of the boom T₁ = 1.33 s, T₂ = 0.32 s, and T₃ = 0.132 s and the corresponding forms of these vibrations are given. It has been shown that when the pump performance is close to the maximum, resonance at a low frequency is possible. Some positions and modes of operation of the boom are considered, in which significant additional dynamic loads may arise in its middle section. Recommendations are given on ways to reduce the dynamics of a concrete pump boom in the vertical plane.

The results of a comprehensive study of temperature modes of bearing units of drive shaft joints under rated loads. Based on experimental studies and modeling of temperature fields, a scientific and methodological basis has been developed for the practical support of automatic thermal diagnostics of moving bearing units during noncontact measurement of their temperature in motion.

This paper provides the results of fatigue strength tests of structural materials including grade St45 steel and VCKh60-2 high-strength cast iron with plasma coatings. These coatings have a relatively large thickness and consist of the powder composition of EP-109 (KhN56VMKYu) heat-resistant nickel alloy and Al–Mg powder. Experiments have allowed deriving mathematical models to describe the patterns of the influence of the plasma spraying process modes on the fatigue strength of the tested structural materials.

The scientific results of modeling a production manipulator are presented. Modeling a production manipulator makes it possible to study its operation in a virtual environment, to optimize the production processes of finished products, and to achieve maximum efficiency in the operation of a machine-building enterprise. The production manipulator is a multipurpose complex device due to the replaceability of the gripper module. The production manipulator was simulated using the Siemens software product NX version 10.

Hydrodynamic processes in a pipeline were studied, and a mathematical model was developed using the finite element method in the Ansys Workbench mathematical modeling package. A mathematical model of the process of gradual opening of a pipeline valve has been developed, which provides a detailed understanding of the flow dynamics and allows us to draw conclusions about the effect of the valve opening on the pressure distribution inside the pipeline.

The elements of kinematic pairs most often used in the design of mechanisms are considered. Possible primary errors for a point, line, plane, spherical pair, sliding pair, and turning pair are presented. The number of primary errors of a connecting rod with elements of two rotational pairs are calculated. Calculation of a cam mechanism is carried out. Recommendations for identifying primary errors in the mechanisms of robotic systems are presented.

The code requirements on drawing up construction design documents do not provide any method of evaluating the mechanical facilities for compliance with the requirements of a construction project. This work is aimed at determining the effective excavator radius, which ensures compliance with the process cycle set by the project. The effective radius of an excavator is the base for designing the excavator working face. A digital model describing each excavator process cycle on one extraction site (working face) has been used as the research tool. Mathematical expressions have been obtained for determining the duration of each excavator process cycle for operation on one extraction site (working face). An area for further studies is identified that consists in theoretically underpinning the position of a bucket discharge point.

In this paper, internal resonances appearing in mechanical systems with several degrees of freedom, when the ratio between the frequencies of their oscillations represent integers, are studied. As specific examples, such systems with two degrees of freedom like a double mathematical pendulum and a double physical pendulum are considered. The relationships for the oscillation frequencies of each of these systems are presented in dimensionless form depending on two dimensionless parameters characterizing the ratio between the weights of the end loads or weighty links, as well as the ratio between the lengths of the links. The conditions that should be imposed on these dimensionless parameters in order to provide for the appearance of internal resonances have been revealed. The obtained solutions are presented graphically in the form of curves on the plane of dimensionless parameters corresponding to internal resonances. In addition, a detailed investigation into the nature of these curves is presented, too. The results found upon analyzing the two problems are compared with each other. The obtained relationships have fundamental theoretical significance, which could be useful for the case of different technical applications.