Journal of Machinery Manufacture and Reliability最新文献

A technology for repairing hydrotreating reactors at an oil refinery using a robotic automated welding/cladding complex is proposed. The technological process of surfacing by means of a robotic welding complex is described for the example of repair of a hydrotreating reactor operated at oil refineries. One of the features of the proposed technology is the use of modern video cameras with laser illumination and liquid cooling. An algorithm for controlling a welding robot based on machine learning methods and fuzzy logic is presented. The technology described contributes to a significant increase in the service life of hydrotreating reactors due to timely repair in the shortest possible time, as well as to an increase in the efficiency of the repair operator’s work by limiting the influence of the human factor.

It is proposed to use the language of mathematical logic (predicate logic) to construct models. Examples of the verbal descriptions of the proposed models for diagnostic processes are presented. In this paper the role played by logical simulation in the analysis of technological systems is considered. In addition to the practical application of this method for an automated technological system of operations (ATSO), the interactions between the components of this system are considered.

In this article, the use of seismic monitoring methods is proposed to solve the problems of automated detection and evaluation of the characteristics of moving railway trains, as well as real-time analysis of the condition of tracks and roadbeds. A mathematical model of the seismic signal from moving railway transport has been developed, with the help of which the modeling of the characteristic impulse arising during the passage of a two-axle wheeled railway bogie was carried out. It was tested using the developed model of the railway transport monitoring system.

Random loading processes in parts of transport and technological machines in operation have a wide range of properties and can also be classified and processed in different ways. Useful tools for analysis, generalized in this article and developed for the first time, were applied to processes of different types. It is shown that transforming a non-Gaussian process to a Gaussian one gives comparable results.

Methods for predicting the sealing integrity of “tube-to-tube sheet” rolled joints in heat exchanger systems are explored, the mechanisms of elastoplastic deformation during the formation of rolled joints are investigated, and the main parameters of the mechanical processes of tube expansion that determine the sealing integrity and reliability of the joint components are established. It is demonstrated that the functionality and sealing of the connections formed by mechanical rolling are conditioned by the level of contact stresses in the zone of plastic deformation of the elements. Finite element modeling of the tube rolling process into tube sheet holes with two annular grooves was performed, providing an analysis of the stress–strain state of the interaction zone after contact formation and under operational loads. The key adverse factors affecting the sealing and strength of the rolled joint were identified.

The results of research into the properties of grain and development of a crushing method that ensures effective grain milling by optimizing the parameters of the grain grinder are presented. The main characteristics of the structural and mechanical properties of barley grain harvested on the plain of Belgorod oblast of the Central Federal District of the Russian Federation and the methods of its milling are studied. Recommendations based on a mathematical model are given for obtaining the required quality of finished products of grain crops processed in conical mills. An installation reproducing real processes of grain grinding in conical mills, with the ability to adjust the process accurately and to output the obtained data to a computer, is proposed.

The modes of electroplastic deformation of the titanium alloy VT6 using three-point bending with subsequent application of the found modes for deformation of the implant blank are examined. The influence of the current density and the pulse duration at a constant duty cycle is estimated. To evaluate the electroplastic effect, the thermal contribution of the current was compared with heating from an external source.

The effect of aging on antiwear properties of lubricants based on solutions of zinc and molybdenum dithiophosphates in oils such as I-20A, PAO-6, and VHVI-6 (viscosity grade 32 by ISO) is studied. Zinc dithiophosphate is known as an antiwear and antioxidative agent, and molybdenum dithiophosphate is a high-temperature antifriction agent. Antiwear and antiscuffing properties have been estimated by GOST 9490-75 using a four-ball testing machine. During the first test, fresh lubricants are used; then they are aged by high-temperature catalytic oxidation using technique no. 42/607 dated May 10, 1983, by VNII NP, and the second test is carried out. According to comparison of the tribological test results for fresh and aged lubricants containing the DF-11 antioxidative agent, the acid number does not increase in some cases, which is caused by the introduction of antioxidation additives in such compositions.

An analysis of the influence of the direction of reinforcement in a composite material relative to the cyclic load on the heterogeneity of the distribution of local elastic strains measured by the thermal method of nondestructive testing is presented. In this study, the possibility of assessing the local distribution of stresses (strains) in the test object is demonstrated using the thermoelastic effect. The temperature field of the thermogram depends linearly on the stresses and strains at local points of the test object. Thermograms of laminates made of composite material with different arrangements of fibrous filler (fiberglass) with an epoxy matrix under cyclic loading were studied. To analyze the differences in the local distribution of strains, statistical data were used and variation coefficients were calculated. To visualize the strain levels, the clustering method and averaging of the temperature distribution values over the length of the laminates were used. The numerical characteristics of local temperature distributions were obtained, which showed a more uniform distribution when reinforcing the material in the direction of loading of the part.

The challenge of selecting sets of technological bases in the design of manufacturing processes for casing parts using multifunctional CNC machining centers is addressed. Through analysis, a graph representing the relationship of part surfaces was selected to depict the linear dimensions, orientation, and position tolerances, as well as runout. Furthermore, the selection criteria for the set of bases were established to include considerations of “impractical” bases, basing errors, the area and stability of the primary base, standardization of basing surfaces, alignment with typical basing schemes, and auxiliary time for mounting and dismounting the workpiece. Thus, considering these criteria, a methodology for selecting the optimal set of technological bases has been developed for the routing process of machining casing parts on CNC machining centers.