Key Engineering Materials Vol. 910

Abstract: The article describes studies of the quality of the surface layer of the deposited metal of a cylindrical part when combining the processes of surfacing and milling, as well as subsequent grinding of the deposited metal in hot and cold states. Photos of the surface of the deposited and processed parts are presented, showing the effect of the processing method on the metal structure and data on the distribution of residual stresses in the surface layer of the metal.

Abstract: Experimental work was carried out on the development of variants of additive technologies of layer-by-layer synthesis (FDM, SLA) for the manufacture of aerodynamic models of aircraft intended for testing in wind tunnels. The material of the models is selected, the production modes and design variants of the models of the fairings of space launch vehicles are described.

Abstract: Additive technologies over the past two decades have formed a technological innovation segment of mechanical engineering: world markets for technologies, equipment have been formed, large-scale research and development work is being carried out, standards for product certification are being developed. The article discusses additive technologies and their definition. The main types of these technologies and their classification are understood. Conclusions on positive and negative aspects of each technology are formed.

Abstract: Adaptation of the previously developed methodology for assessing risks and opportunities for assessing risk situations and identifying opportunities during operation of built-up cutting tools is made. The factors influencing performance of built-up cutting tools are analyzed. The article presents an analysis of failures of replaceable inserts of built-up cutting tools when performing face milling operations, the results of which will be taken into account when applying the developed technique.

Abstract: This article describes application of the method of turning the cylindrical surface of the part using the flank surface of the cutting plate. The comparison of classical turning and the use of ‘back turning’ was carried out, the area of rational application was revealed and the combined use of the methods was proposed. A finite element model of the part, tool and equipment was created for calculating deformations in the system and internal stresses. A control program for part machining using a combination of both machining methods was designed.

Abstract: To obtain the desired shape of long panels and sheaths in the aircraft industry, the technology of shot peen forming with subsequent grinding with flap wheels is successfully used. To implement this technology, a special UDF-4 (shot peen forming equipment of the 4th version of modernization) device was designed and manufactured. The last version of this device is equipped with a CNC system and a revolver head with the 4-flap wheels for optimizing the grinding operation. The ability to select the desired flap wheel during the grinding process, depending on the curvature and width of panels or sheaths, has significantly expanded the technological capabilities of this equipment. During grinding with flap wheels of a rectilinear profile, to ensure uniform removal along the cross-section of the part’s curvilinear contour, it is necessary to carry out processing with overlapping previous passages. The need for overlapping passages significantly increases the processing time. At the same time, the calculation of the overlapping width during the changing curvature of the part’s profile is quite a difficult task. This paper presents analytical studies of the use of profiled flap wheels for grinding the part’s surface with a variable radius of transverse curvature, and also proposed the mathematical models for selecting the necessary profiled flap wheels depending on the curvature of the part’s processing surface.

Abstract: The paper presents a developed a technology for producing a new abrasive material, which is a refractory ceramic matrix made of aluminum oxide with embedded diamond particles. The tests have shown its advantage over traditional diamond-bearing materials when processing high-hardness ceramics. To synthesize a new material with a predetermined set of operational parameters, it is necessary to build a wear model of a friction pair composed of diamond-bearing ceramic material and ceramics. After analyzing the results of other authors’ studies and assessing the morphology of the contacting surfaces, it is assumed that the contact of microroughnesses on the friction surfaces of abrasive diamond-bearing ceramic tools is linearly elastic. The model is built within the framework of the basic wear equation. The composite material surface was modeled by a set of same radius spherical segments; diamond grains were distributed in the material with a given bulk density. The paper uses the concept of an equivalent surface with the power law distributed of microroughnesses tops. A theoretical relationship is obtained between the micro-and macrocharacteristics of the wear process of a composite ceramic friction pair. The authors established theoretically and confirmed experimentally that the grinding productivity increases with an increase in sliding speed, applied load and diamond grain size. The diamond concentration has no significant effect on the workpiece wear. The established dependencies can help to achieve high productivity of diamond ceramic tools.

Abstract: A number of parts of roller-screw mechanisms (RSM), which work in aggressive environments, are made of corrosion-resistant stainless steel 40Cr13 (AISI420 analogue). These elements include a screw and rollers. For these parts, it is necessary to have hard surface layers and a soft core. A promising method for obtaining the necessary requirements is surface laser modification. The article investigated the effect of laser surface treatment on the value of the coefficient of elasticity, hardness, coefficient of friction and the amount of wear of products made of stainless alloy steel 40Cr13. For laser processing, the SVAROG-1-5DR laser complex (Russia) was used. Various modes of surface laser modification were set. For this purpose, the power of the laser power, the speed of movement of the laser beam relative to the treated surface, and the focal length were varied. The Vickers hardness and tribological characteristics were measured using a microcombitester and tribometer manufactured by SSM Instruments SA (Switzerland). The Rockwell hardness was measured using a TN 301 hardness tester manufactured by Time Group (China). The structure of the alloy was studied by metallography and X-ray diffractometry. It was found that the indicators of hardness and wear resistance of the surface layers of sctructural 40Cr13 steel strongly depend on the laser treatment modes. These dependencies are extreme, with highs and lows. The paper presents the quantitative values of the hardness and wear resistance indicators before and after laser treatment of the surface of this steel in various modes. The reasons for the change in the hardness and wear of the surface layers of 40Cr13 steel after laser treatment under different modes are established. The results of the work were used to optimize the modes of laser treatment of the surface of 40Cr13 steel in order to obtain the maximum values of hardness and wear resistance.

Abstract: The article describes the design and purpose of a turbopump unit, in particular, the pump body of the liquid rocket engine turbopump unit. The technology and technological equipment for obtaining complex profile holes in the turbopump units body are presented. The design features of technological process and equipment for electrochemical processing are considered. The proposed technology and devices allows to process parts of the liquid rocket engine turbopump unit with special holes.

Abstract: This paper describes the experimental study and modeling of the process of cross wedge rolling workpiece for the stamping of the crankshaft using a tool printed on a 3D printer. The study shows the design and printing features of the tool for cross wedge rolling. A comparison of the experiment and simulation in Qform program.