METASTABLE STRUCTURE OF AUSTENITIC MANGANESE ALLOY AND PROSPECTS FOR CREATION OF PARTS BASED ON IT

Comparative microstructural studies and mechanical tests of an experimental austenic manganese alloy and typical structural materials have been carried out. As a result of the research, relative data have been revealed, indicating high mechanical properties of the experimental alloy, which makes it possible to recommend it for machine parts operating at high load-speed operating conditions and temperature exposure up to 700 0C.

Controlling the Stress State of the Coating during Plasma Spraying

Coatings obtained by spraying materials with a high-temperature gas jet onto a substrate followed by thermal treatment of the deposited materials (thermal gas coatings) are increasingly being used. The practical experience of using thermal spray coatings, accumulated over the past 20–30 years in industries, shows that in this way it is possible, as a rule, to reduce the wear of machine parts operating under various conditions by a factor of 2–5. The effectiveness of the technology has also been proven in the protection of products from corrosion and thermal damage. The efficiency of the applied materials is determined by their structure, which largely depends on the choice of the composition of the material, the method, and modes of application. A comprehensive solution to these issues with the study of the mechanism of the processes of formation of thermal gas coatings will create a scientific basis for the technology for its successful implementation in production. At the same time, the importance of studying the processes and optimizing the technological parameters of spraying and subsequent coating treatment increases. Optimization is carried out, as a rule, according to the results of experiments. Let us consider the study on the example of the development of wear-resistant composite coatings with solid lubricant inclusions with the substantiation of the technique and criteria for optimizing technological parameters taking into account the most important properties of sprayed protective coatings.

Theoretical Justification of Coating Adhesion during Gas-Thermal Spraying

The article provides a brief overview of modern methods of thermal spraying. Particular attention is paid to high-speed flame spraying. The theoretical substantiation of the adhesion of coatings formed on machine parts using the methods of thermal spraying is presented.

Energy-efficient omd processes with complex local loading for the production of machine parts with a given level of properties

The article discusses some new energy-efficient metal forming processes (PMD) with complex local loading of the deformation zone for the production of machine parts with a given level of properties. The place of such processes in the aggregate of all OMD technologies is shown, and their classification is given. The initial data of numerical mathematical modeling of the specified class of processes for a particular case are given, the features of the stress-strain state of the metal in the deformation zone are revealed. In the study, from a theoretical point of view, one of the important practical aspects of these technologies is considered: the effect of the value of axial compression on the shape and size of the deformation zone arising from the action of local loading of the workpiece.

Application of computer technologies for calculation of gears at studying of a course " Details of machines"

The computer program GearKURT has been created to calculate mechanical gears. The program allows you to calculate gears: - closed cylindrical spur gear - closed cylindrical helical gear - open cylindrical spur gear - Novikov's gear - closed bevel spur gear - closed bevel gear with indirect teeth - open bevel gear - worm-gear. The computer program has a dialog interface written in the object-oriented programming language Delphi and compiled into an exe-file. The program allows you to choose the necessary material and method of heat treatment for the manufacture of gears, to calculate the optimal geometric dimensions and transmission parameters, to determine the design of gears. The program provides all the necessary reference materials in the form of tables and graphs, which must be used to select the coefficients and other values necessary for calculations. The program provides access to the theoretical material of the course "Machine Parts" and the ability to save the results of calculations in a separate file. Recommendations for using this program are given.

RESEARCH AND EXPERIMENTAL STUDIES OF STRESS-STRAIN STATE OF DISCRETE-CONTINUAL HARDENED MACHINE PARTS

Research and experimental studies of stress-strain state of discrete-continual hardened machine parts are presented in this work. This hardening method is distinguished by incorporation of numerous hard spots into the surface layer of one of the bodies. Meanwhile the other part is covered by a continuous corundum layer. Correspondingly, a network of microchannels for lubricant is formed between the bodies. Furthermore the contact loads are intensified in the vicinity of the harder material in the discrete zones. As a result the strength and durability of the loaded parts is increased. The technological parameters of the hardening process have great impact on the resulting characteristics. In particular, this concern the shape of the discrete hardening zones and the material properties of the corundum layer. These factors were varied in stress-strain analyses of the contacting bodies. The dependence of the stress-strain state characteristics on the varied parameters was established. The justified recommendations regarding the technological parameters of the discrete-continual hardening have been developed. Keywords: stress-strain state, discrete-continual hardening, contact interaction, finite element method, contact pressure, machine parts

IMPROVING THE PERFORMANCE CHARACTERISTICS OF MACHINE PARTS BASED ON THE COMBINED INFLUENCE OF STRONG MAGNETIC FIELDS

Magnetic treatment is a promising method of hardening. Metal exposed to alternating magnetic fields changes the performance properties of the surface layer of a combination of magnetic and ultrasonic effects, provides a combined method of processing and strengthening surfaces of machine parts, which eliminates the main disadvantages of magnetic and electrical hardening — instability of physical and mechanical properties of this layer with detail. The purpose of the work is to investigate the possibility of improving the performance of machine parts based on the combined effect of strong magnetic fields. The study of the use of a uniform flux of magnetic fields generated by powerful permanent magnets was performed to affect the material volume of non-grinding plates of the cutting tool CNMG_120508E-M. The effect of uniform magnetic flux is initiated as a result of resonant oscillations of the sample caused by broadband exposure of equal amplitude by means of a "white noise" generator and a piezo emitter. The authors found that as a result of volumetric strengthening of non-grinding plates of carbide cutting tools, by exposure to polyfrequency oscillations in the form of a broadband frequency spectrum of equal amplitudes, a significant reduction in dimensional wear of the plates is achieved. Adding mechanical vibrations to the samples in a uniform constant magnetic field allowed to achieve volumetric hardening of the samples from 150 HB to 240 ÷ 250 HB, ie 60 ÷ 65% in 10—12 minutes, which is the hardening of the samples by 5—6% in one minute. The work on determining the relationship of changing properties with processing time, frequency range, amplitude and other modes to find the optimal values ​​of processing parameters, has great prospects for the ability to obtain a set of performance characteristics, control external and internal properties of products.

Investigation of frictional impact on polyester yarn during knitting

The usage of polyester (PET) in fabrication is increasing day by day due to its properties, ease of physical and chemical modification. The aim of this work is to understand the effect of temperature on Polyester (PET) during knitting. For checking the rise of temperature Infrared (IR) camera is used. Microscopic images are used for studying the effect of temperature on fibre/yarn structure. Morphological analysis is also done by X-ray diffraction (XRD) which shows disturbance of polymeric chains, causing change in crystal size due to elevated temperature. The beads formation and filament breakage are clearly seen in images. Due to this knitting fault, shade variation after dyeing occurred. It is concluded that structural morphology of polyester yarn changes due to friction of yarn with knitting machine parts. Fabric appearance and fabric quality also disturbed which leads to rejections and high losses.

Cloud system for decision supporting of technological process of restoration of surfaces of structures and machine parts

The object of research is the process of decision support of the technological process. The subject of the research is the decision support system of the technological process of restoration of surfaces of structures and machine parts in the form of cloud service. The purpose of the work is to develop a decision support system for the technological process of restoration of surfaces of structures and machine parts in the form of cloud service, which will further optimize high-tech processes of enterprises of various scales using cloud information technology. As a result of the research, the difficulties of automating the design of technological processes are analyzed, mainly due to the fact that the tasks of technological process design do not currently have formal methods of solution. Therefore, for the implementation of technological design, the development of formalization of technology (or part of it), ie the replacement (transformation) of meaningful proposals by the mathematical apparatus. As a result of this formalization, a scheme of information flow in the process of process optimization is proposed. the model of realization of structure of technological process for which the basic input parameters are defined is developed: the list of parameters influencing process. The structure of the expert system for optimization of technological processes was also proposed, the methods of knowledge presentation were analyzed and the scheme of information flows during the implementation of this expert system was developed accordingly. Based on the considered and developed methods and mechanisms used for the development of technological processes, the structure of the information cloud decision support system for automation of the creation of optimized technological processes has been developed. Using the developed methods and models, as a result of the process of process optimization according to acceptable heuristic rules, it was possible to obtain a set of chains of separately optimized technological processes, from which multicriteria selection that meets the optimization requirements. The user of the system can receive in return both one card of technological process, and some best. Conclusions. The developed approaches to the optimization of technological processes were applied to solve the problem of optimization of the technological process of electric arc processing. First, the technological process of electric arc processing was formalized. After that, the formation of heuristic rules and knowledge base of the structure of the technological process of electric arc spraying and accordingly developed the structure of the knowledge base of this technological process and a diagram of the use of the developed information system in the form of cloud service.

Extreme Clusters of Grains in Random Microstructures of Polycrystals

It was experimentally observed that in polycrystalline materials under low macro loading of the specimen the first sites of failure initiation take place in the specific clusters of few grains. In some grains of these extreme clusters, the local (meso-) strains and stresses are high enough to cause first damages or plastic slips. In the stochastic microstructure of polycrystals, the formation of an extreme cluster is random and rare. Nevertheless, they govern the failure process initiation and can severely affect the reliability of polycrystalline machine parts. It is time and resource consuming to search and investigate extreme clusters on the real specimens of polycrystalline materials experimentally. A theoretical tool is desirable. Here we present the powerful computational method to look for extreme clusters, to investigate their possible patterns, and to evaluate the absolute maximums of local strains/stresses that can be achieved in these clusters. The experimentally observed clusters consist of few (3-4) preferably oriented neighboring grains or even of one big supergrain. The strain and stress bursts arise due to an interaction of the grains. One can expect that in bigger clusters, larger local bursts of fields can be generated. We found the typical forms of the extreme clusters (small and big) in four different polycrystals with grains of a weak and strong anisotropy for the case of uniaxial tension. In all regarded cases, the extreme clusters have the forms of the symmetrical patterns. In big clusters of highly anisotropic grains, the maximum of mesostrain exceeds the macrostrain by several times. In clusters of weakly anisotropic grains, the local strain concentration is rather moderate (tens of percents).