Bulletin PNRPU. Mechanical engineering, materials science

The development and application of resource-saving technologies aimed at obtaining metal products and structures with high strength and operational characteristics allows enterprises to obtain a number of competitive advantages. The achievement of such advantages, to a large extent, is facilitated by the possibility of expanding the range of metals and alloys used, as well as the return of materials to the technological cycle. The implementation of these tasks is aimed at using the technology developed at the IMiM FEB RAS for producing durable material deposited on structural elements made of steels with a high carbon equivalent. The strength characteristics of such steels, as a rule, are significantly superior to materials widely used for welding and surfacing, but their use is limited by additional technological requirements. So, for example, for surfacing on steel 45, the use of an arc process with heating and subsequent heat treatment is required. In addition, due to the tendency of this steel to form cracks and pores in the heat affected zone, its traditional use is limited to lightly loaded structures. The essence of the process being developed is to combine the effects of an electric arc and an aluminothermic process on a steel surface. The technical solution is implemented through the use of an automatic arc welding machine under the flux layer of the electrode, made in the form of a flux-cored wire with aluminothermic filler. The filler is a mixture of reducing agent and scale, which is a waste of mechanical engineering. The combined process creates the conditions for introducing additional heat of the exothermic reaction, and also allows to improve the thermal insulation of the deposition zone due to the forming slag. The possibility of using the potential of carbon steels to obtain a strong permanent connection determines the relevance of research in this direction. The influence of the thermal regime on the formation of the strength characteristics of the material deposited on a plate of steel 45 is considered.

Melchior is an alloy of copper and nickel; small amounts of iron and manganese are added to change some properties of this alloy. This alloy is quite well processed in cold and hot conditions, and also has a high corrosion resistance. The color of cupronickel is silver, it is visually difficult to distinguish from silver, due to such a feature of cupronickel, the alloy has been widely used in jewelry de le. It is also used in the manufacture of medical instruments, high-quality parts of marine boats and in precision mechanical products. The strength and corrosion resistance of this alloy increases with increasing nickel content. In the current conditions of industrial production, improvement of the technological and service properties of alloys is possible with the expansion of fundamental scientific research and the development of new technological conclusions based on them. The novelty of the research lies in the development of the original applied direction of materials science in mechanical engineering: the development of recommendations on the temperature-time regime for melting nickel silver MH19 based on the ideas about bringing the melt into a state of kinetic and thermodynamic equilibrium in order to improve and stabilize product quality. The temperature dependences of the structurally sensitive properties of a copper-based liquid alloy are investigated. On polytherms identified special points and sites. New experimental data on the physical properties of nickel silver brand MH19 are obtained. Kinematic viscosity, surface tension, density and electrical resistivity were measured in the temperature range from liquidus with an excess of 300-400 ºС. The polytherms obtained by measuring the kinematic viscosity, electrical resistivity, surface tension and density are constructed and presented. Based on the obtained experimental data, the following recommendations are proposed: minimum heating to a temperature of 1400 ºС, exposure ≈5 min for homogenization of the melt.

An important characteristic that determines the performance properties of a material is the damping. Damping is responsible for noise dampening and vibration dampening occurring in a particular equipment. At the same time the damping properties can be changed using both standard methods of heat treatment and more promising methods - methods of thermomagnetic treatment. This paper studied the effects of the thermomagnetic treatment temperature on the damping capacity, coercive force and the structure of high damping Fe-Cr-Al alloys with a content Cr = 5.2-19.9 %, Al = 0.4-3.8 %, subjected to the pre-annealing. Thermomagnetic treatment was performed at the temperature range 300-850 °C with an alternating magnetic field strength 4A/cm. Damping properties were studied with a reverse torsional pendulum at the cylindrical samples. The used methods: amplitude-dependent internal friction, coercive force and X-ray diffraction analysis. It is shown that thermomagnetic treatment leads to both an increase and a decrease of the damping capacity; it depends on the temperature of the thermomagnetic treatment. It was determined the thermomagnetic treatment temperatures corresponding to the maximum damping alloy capacity, taking into account the influence of two alloying elements Cr and Al. It is shown that while study the damping and magnetic properties of Fe-Cr-Al alloys obtained as a result of thermomagnetic treatment, it is necessary to take into account the processes of phase transformations that affect the formation of the magnetocrystalline structure. The processes depending on the chemical composition of the alloy are the processes of α«γ transformation, formation and dissolution of carbides, segregation of chromium atoms, Fe3Al phases. It is also necessary to take into account the possibility of overlapping these processes.

This article describes the basic problems of FFF / FDM 3D-printing relates to the behavior of plastic melt in the hot part of the extruder. A more mobile and easily accessible technology for printing plastic products of complex geometric shapes based on FDM technology of 3D-printing developed by the scientific team of Perm National Research Polytechnic University is represented. A comparison of a standard extruder developed by the authors of the article is given. It is concluded that FDM technology has not fully revealed its potential due to a wide range of technical problems. The range of issues to be solved for the successful manufacture of plastic products using this technology is considered. Hypotheses and ways of solving problems are being put forward. Prospects of this technology are considered, as well as an assessment of its utility in production and for society. The methodology and results of modeling the behavior of the polymer melt inside the FFF/FDM 3D printer special shape nozzle are presented. SolidWorksSimulation was used as a modeling environment for determining the eveness of heating of the hot-end of a standard extruder and a new type extruder. To calculate the maximum polymer passage through the nozzle of the developed extruder under the condition of even heating of the hot-end (nozzle), an multi-physical axisymmetric mathematical model was constructed in the ComsolMultiphysics package, which containing a thermal and electromagnetic tasks. The simulation results allow to determine the ratio of print speed, length and temperature of the heated part for 2 types of polymer. This dependence can be used to control the temperature of the nozzle and the feed rate of the polymer thread directly during printing. Such regulation will ensure a higher quality of manufactured objects.

The operational properties of gears are largely determined by the accuracy of the manufacture of gear parts and the quality of the working surfaces of the teeth. In order to ensure the operational characteristics of products, a significant place in the technology of manufacturing gears is given to finishing gear processing. The requirements listed above are especially important in the manufacture of a working pair of multi-screw helical gerotor mechanisms of hydraulic downhole motors. To select the optimal process of finishing processing in the manufacture of complex shafts, the classification and analysis of all existing methods and schemes of finishing gear processing, as well as an assessment of their technological capabilities for the accuracy and roughness of the working surfaces, have been performed. From the analysis, it was found that none of the well-known methods for finishing machining gear surfaces can be used to implement the finishing treatment of complex shafts, since a number of methods constructed according to the rolling pattern can be implemented only for involute surfaces, since the tool profile is based on a straight contour gear cutting slats. Finishing methods implemented according to the copying scheme do not provide high degrees of accuracy of gear surfaces. The tooth profile of the rotor of a helical downhole motor has the shape of a shortened epicycloid in the end section and cannot be implemented either according to the kinematic rolling scheme or according to the copying scheme due to the difficulties with the exact manufacturing, editing and control of the tool contour. It has been established that the method of abrasive globoid gear honing, which is easily implemented both according to the kinematic rolling scheme and the free rolling scheme, has the greatest versatility and ease of implementation in the production process. The method has a linear contact in the processing zone, which increases productivity and high processing accuracy due to the features of engagement and averaging of profile errors. With the right choice of characteristics of the abrasive layer of the globoid hone, the processing scheme is easily implemented using the kinematics of existing machines without designing special loading devices.