Scientific schools and developments of the department

FOUNDER OF NEW SCIENTIFIC DIRECTIONS

Based on the department of technological systems of repair production more than 70 dissertations were prepared and successfully defended, the partial list of which is given below

NEW SCIENTIFIC DEVELOPMENTS OF THE DEPARTMENT “TECHNOLOGICAL SYSTEMS OF REPAIR PRODUCTION” IN THE FIELD OF “MECHANICAL ENGINEERING”

The activity of the department “Technological systems of repair production” is generalized. For 25 years of research and educational activities at the department developed the latest technologies in 6 areas of research, which were used in the educational process and implemented in production.

The research work of the department “Technological systems of repair production” was based on the priority areas of science and technology development, which correspond to the innovative activity and scientific school of employees.

This became possible due to creative cooperation with specialists of various metallurgical and machine-building enterprises, as well as – Kharkiv region, which includes the plant. V.O. Malysheva, HTZ, National Research Center “Kharkiv Institute of Physics and Technology” (NRC KIPT) and the company LLC “Special Scientific Developments”.

The main areas of research were conducted to improve the quality of products with different approaches. These include the following

1) production of new types of forming tool for hire of different assortment;

2) new technological processes in mechanical engineering by strengthening with highly concentrated energy sources – laser, plasma, electro spark, radiation methods;

3) creation of new equipment and technologies for the restoration of parts (hydrogen-oxygen flame, coating with dosed impurities, heat treatment, special deformation, etc.);

4) to save energy and materials, developed technologies for the restoration of parts using secondary raw materials, as well as new approaches to their use;

5) development and implementation of nanotechnologies for strengthening and restoration of parts and products for various purposes;

6) development of effective directions of quality control with the use of new non-destructive methods.

This set of innovative areas of research was made possible by the equipment of the department, which includes not only special equipment for research activities at the first stage of development but also computer classes, 3D printer, which allowed to conduct theoretical research, model processes, and develop a set of optical and mathematical methods for estimating the phase composition and the ratio of structural components with different methods of hardening and stages of operation.

Thanks to such approaches in the scientific activity of the department for 25 years of its work in the institute “Technical service” 24 candidates and 3 doctors of technical sciences were prepared, and only 2 of them were not employees of the university.

The developed developments are innovative and this is confirmed by references in Scopus (59 publications) and h = 4.

The main staff of the department is stable and trained specialists of the highest qualification successfully work in other institutes of KNTUA. P. Vasilenko. Currently, the department “Technological systems of repair production” researches by 6 candidates for the degree of candidate of technical sciences and 4 – doctor of technical sciences.

Let’s briefly consider each area of ​​research performed during this period by specialists of the department. According to the first direction, new technologies of production of rolled and flour-rolling rolls from high-carbon alloys which differ in the increased level of operational properties are developed. This is their casting by centrifugal casting on machines with vertical and horizontal axes of rotation. To ensure the required quality and increase their operational stability used additional alloying, modification with various impurities (secondary raw materials – slag, coal ash, modifiers of different generations, including Supersized, Resid, which appeared in production only in recent years). For their use, special technological processes have been developed, which have provided stable properties of alloy modification. The efficiency of liquid state treatment processes was solved by adjusting the crystallization rate of the working layer by special pre-treatment of equipment, for example, heating the metal casting to a temperature that provides the necessary parameters of phase transformations in the temperature range 700 → 500 ° C and 200 ° C (magnetic transformation of carbide phase). , or 400-450ºС – for the high-alloy tool (high-chromium cast iron). With such production parameters, the tool may not be heat treated because it has minimal stresses and provides a maximum decomposition of residual austenite, which significantly reduces its susceptibility to chipping during operation. This production technology, depending on the material of the rolls provides an increase in their life by 7.7-17.0%. Methods of out-of-furnace treatment of liquid metal in ladles by vacuum and gas purging also make a significant contribution to improving the quality of high-carbon roll materials.

New energy-saving technologies for the production of tools for metal forming (rails, grades, sheets – thick and thin, for agricultural machinery) have been developed on the subject of scientific activity of specialists. These are products weighing from 1.0 kg to 36 tons.

Based on theoretical researches, calculation of a thermal condition of working rolls, and a rolling strip the technique of designing the cooling system is developed. It is effective for hot rolling mills: 1700, 2800, and 3000. The new technology provides energy and resource savings and reduces by 25% the need to cool the rolls during operation, as well as reduces the pressure of metal on the rolls in the busiest aisles, increases the flatness of the metal, reduces the need for a forming tool by 10% by optimizing the thermal mode of operation at the mill.
Забезпечення високою плоскостності металу сприяє підвищенню якості виготовлених деталей штампуванням у машинобудуванні, а також при виробництві гнутих профілей.

The authors of the presented work also performed modeling and then obtained a special deformed bent profile for 180˚. Its deformable state is investigated. Effective energy parameters of roll deformation of long-dimensional products with long-formed corrugations are developed. Factors of low-quality formation of corrugations are revealed and the substantiated parameters of their reception by the manufacturer are given.

Specific products and parts used and developed for various industries are reflected in the areas of mechanical engineering (transport, heavy, agricultural, processing, and food industries).

Several products supplied by the metallurgical industry are particularly responsible for the transportation of goods and the functioning of Ukraine . These are such as rails and rail linings because they are responsible for the movement of rail transport, traffic safety. In this area of ​​research, the latest technologies were based on a detailed study of the primary structure of the ingot of rail steels (made by traditional methods and blanks of continuous casting) to- and eutectoid content, the quality of various heat treatment technologies. The influence of chemical composition and properties of metal on operational stability of rails and formation of contact-tired defects, fractures are established. Based on research, the use of microalloying impurities – vanadium, is recommended, due to which high-strength rails were obtained in steels with a higher fraction and.

Recommendations on the equipment and technological parameters of annealing of HDTV rails (high current) and substrates – electronic radiation are developed. Developments are the latest and implemented and are used at the metallurgical plant of PJSC MK “AZOVSTAL”, where 3 lines of rail annealing machines operate.

Much attention was paid to the influence of profile forming and heat treatment technologies on the liquidation of components in the rails, which harm the formation of the structure, which is not allowed by the current regulatory and technical documentation. To do this, special approaches have been developed to detect such a structure (bainite, martensite) by the optical-mathematical method.

The introduction of new technologies for the production of rails was carried out on a special track with load control and changes in ambient temperatures. Failure factors were evaluated and the quality of the metal was adjusted by doping, microalloying, modification, and pre-annealing treatment to obtain a spheroidal structure of perlite.

The results of the developments were implemented at the Lutuhyn Research and Production Plant of Rolling Mills, as well as by metallurgical enterprises of Ukraine, CIS countries and far abroad (China, Germany, Poland, India, Mexico, Romania, Czech Republic), to which the products were supplied.

According to the second area of ​​research related to mechanical engineering, they were based on many years of experience of the team, which confirmed that the effectiveness of restoration of equipment depends on the quality of metal and the use of new, innovative technologies.

In this regard, the department has performed a series of works, which includes interrelated areas based on experimental, theoretical, industrial research, and implementation in production.

New research methods (according to coercive force, the optical-mathematical method for estimating metal structure, special measurements of micro- and nano hardness, elasticity, wear resistance, etc.) were developed, which were used to assess the degree of stresses, mechanical properties, the decay of residual austenite during heat treatment, installation quality of the applied coverings, and also for detection of defects in castings, at stamping and changes of their structural condition of metal before and after the operation. This was used to adjust technologies that provided optimal production parameters. Special stands were created to test the latest restoration technologies.

The success of the creative team in the field of mechanical engineering is as follows. Based on the study of specific operating conditions of parts with an assessment of the factors of their failures, with the establishment of stages of mental degradation and the behavior of conjugations, attention was paid to the search for new technologies to improve operational stability. The processes of friction and wear were modeled on special equipment in experimental conditions, theoretical calculations in different tribosystems. Such developments were the basis for providing recommendations for use in production. To ensure increased operational stability, special effective impurities to lubricating media were used and recommended. As shown by complex studies, the components of impurities together with oxygen create a film protective coating and significantly increase wear resistance. The thickness of these film coatings is not uniform and varies on the friction surface from 300 to 700 nm. It is established that the most effective impurities to lubricating media are those that contain enough oxygen. Therefore, mixtures obtained by the detonation method from secondary raw materials, which are saturated with this component, were effective. For the first time, studies were conducted to assess the effective use of the detonation charge obtained from the disposal of ammunition. It was divided into composition and fractions: magnetic and non-magnetic. The latter contains nanodiamonds and graphite, which were used not only as an impurity to reduce wear, the coefficient of friction in the couplings, but also – a modifying component of the liquid state in the restoration of parts by surfacing.

Based on the behavior of conjugations in operation, assessment of the degree of wear and degradation of metal parts, methods for their restoration (surfacing with additional alloying or modification, use of nanocoatings, strengthening by plastic deformation) have been developed.

Maintenance of the required technical condition and indicators of reliability and efficiency of machines, units, equipment was provided by their timely maintenance, repair, and restoration of parts using the latest technologies, which increased their stability to 40%.

Particular attention was paid to the calculation of parameters of restoration and strengthening of parts at the enterprises for the repair of equipment. For this purpose, a special classification of parts has been developed, according to the choice of the method of their effective restoration. It is based on the surface of the parts, which is planned for restoration and is divided into 11 classes. These are details of the type of bodies of rotation and those that are not. The classification includes the main areas of recovery. Recommendations for the use of the equipment and new recovery technologies are provided.

Developments of restoration of details with the use of highly concentrated energy sources were effective. This is the restoration of shafts for various purposes by electro spark and plasma methods, electrolytic coatings of piston rings with subsequent treatment with low-temperature plasma to heal defects – pores, cracks, and other defects strengthening of long parts by the laser beam and rail substrates – electronic.

According to the third area of ​​research, the department has improved and created new equipment for testing and implementation of new technological processes. These include equipment for welding by various methods (use of laser and plasma complexes, created auxiliary devices for innovative technologies for the restoration of parts of different shapes and weights).

Creation of equipment for electrolytic coating by chromium plating and iron use with the use of nano purities, which are uniformly distributed during crystallization.

Such equipment allows developing optimal technological processes of strengthening and restoration of working surfaces with the dosed introduction of modifying impurities and to control their influence with the use of metallographic methods of researches, physical and mechanical tests, modeling of the optical and mathematical description of phase structure and their ratio on photos of microstructures. At the same time, the technology of reducing pore formation and cracks during chromium plating with low-temperature plasma treatment of such a coating on piston rings has been developed. Equipment for hydrogen-oxygen welding has been created, which significantly reduces the use of energy.

When conducting experimental research, modeling of technological processes, the specialists of the department cooperate with well-known researchers of the Kharkiv region: the plant named after V.O. Malysheva, HTZ, UFTI, KhPI, and others.

In the fourth area of ​​research to save energy, materials, new approaches are used, which relate to effective methods of hardening special conditions for adjusting the parameters of casting, plastic deformation of products during their crystallization, hardening, and modification of new generations of impurities and secondary raw materials.

To save energy consumption of high-alloy products, special methods of cyclic low-temperature heat treatment of high-mass castings for the most complete decomposition of austenite have been developed.

The introduction of modifying impurities has increased the physical and mechanical properties and their operational stability.

The novelty of such developments lies in the methods of introduction of impurities, ensuring their uniform distribution, achieving the required level of properties, reducing the tendency of restorative coatings to pore formation, increasing adhesion to the substrate. Such technical solutions allowed to introduce not only dosed alloying components but also nanodiamonds, which do not dissolve, do not aggregate and ensure their uniform distribution, do not settle in a liquid solution. The new approach to hardening with the use of a special device for surfacing significantly provide increased hardness, wear resistance, reduction of grains in the structure of the restored layer, the high-quality connection of the coating with the base.

According to the fifth area of ​​research, related to the development and implementation of nanotechnology, nano-coating reinforcement was developed for thin-walled knives for chopping nuts. At the same time, design solutions, the use of various components of coatings, and the optimal thickness of the layer were introduced. The possibilities of overheating of thin-walled products during hardening, as well as one-time achievement of not only hardness indicators but also such as fatigue strength, self-sharpening, susceptibility to corrosion, which is important for the food industry, were taken into account. The strengthened tool not only provided an increase of durability, but also the safety of use (excluded a possibility of destruction at operation with a hit of metal in production).

For the first time, special devices have been developed for a one-time hardening of 16 knives with adjustment of the coating thickness from 900 nm to 4 μm without overheating of the cutting edge of the tool with a thickness of 0.1 μm. At the same time strengthening from only one surface of a knife was used that provided its self-sharpening at operation. Pre-RF treatment of the cutting tool reduced the susceptibility to corrosion, which also contributed to the cleaning and smoothing of pores on the surface of the source metal.

The thickness of the coatings up to 4 μm without overheating was provided by the cyclic application of nanolayers. Such a comprehensive solution to the problem was achieved based on theoretical calculations of temperature fields, evaluation of the diffusion of carbon and alloying components, identification of the nature of the formation of zones of deformation and stress. The quality of the tool during manufacture, hardening, and operation was evaluated by specially developed methods of non-destructive testing.

The new tool hardening technology was developed together with UFTI specialists and implemented at PJSC Kharkivkyanka Confectionery Factory. The wear resistance of knives significantly depends on the coating thickness and the initial quality of their metal. With the improvement of the quality of cold-rolled metal knives and their hardening to 4 μm, the resistance increases from the processing of nuts from 0.9 tons to 200 tons when using one set of tools. This technology is the latest and its use for thin-walled tools has been developed and implemented for the first time.

Creative cooperation of scientists with specialists of LLC “Special Scientific Developments” has made a significant contribution to the creation and adjustment of new production technologies, strengthening, operating conditions on the level of coercive force, which reflects changes in structural condition and stress levels of products during their operation. . Such developments belong to the sixth area of ​​research.

Using the method of non-destructive quality control for products and parts of different shape and content of components, based on many years of research, which allowed setting a timely task in each case of measurement specialists in the development of devices.

Studies have shown:

• the degree of influence on the measurement of the shape of the product or part (the degree of contact of the transducers with the surface being evaluated);
• the degree of influence of the phase composition of the metal (especially the proportion of austenite);
• the degree of influence of stresses in the products during their production, heat treatment, hardening (depending on the methods of production and quality of the metal);
• the degree of change in the cross-section of the working layer of the product depending on the hardening technology (single use of magnetic transducers of different sizes).

the degree of influence on the measurement of the shape of the product or part Such equipment is particularly effective for use in assessing the degradation of metal structures in the period before their destruction with the prevention of hazards. New equipment and measurement technologies are specially developed for the use of coatings from nano- to macro-thicknesses.

Developments using equipment and measurement technology are reflected in the prepared standard SOU 29.32.4-37-532; 2006 “Non-destructive magnetic quality control during maintenance and repair” and were marked as “The best domestic product of 2014.” (degree of contact of transducers with the surface being evaluated);