Перегляд за Автор "Molnar, Viktor"
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Документ Analysis of the Sbi and Svi functional indices in hard machining(Національний технічний університет "Харківський політехнічний інститут", 2022) Molnar, ViktorThe functional requirements of precision machined parts can be expressed among others by topography parameters. In the automotive industry there is an increased need for the application of high-accuracy quantifying parameters. In this study wear resistance and the fluid retention ability-related 3D surface texture parameters are analyzed based on hard turning and grinding experiments. The less frequently applied functional parameters (Sbi and Svi) are compared to the high-accuracy volume parameters (Vmp and Vvv) to obtain information about the reliability of the former ones. It was found that the correlation between the two types of parameters are quite weak.Документ Analyzing surface integrity elements of hard turned 16MnCr5 steel(Національний технічний університет "Харківський політехнічний інститут", 2023) Molnar, ViktorSurface integrity plays a determinant role in the functional requirement of precision machined parts. In the automotive industry billions of components are manufactured by using case hardened steels. In this study some surface integrity elements, such as surface roughness or residual stress are analyzed based on systematic machining experimental plan to optimize the applied cutting parameters. Recommendations are made for these parameters based on the measurement data and some widely used functional requirements.Документ Decision support method for the applicability of hard turning(Національний технічний університет "Харківський політехнічний інститут", 2022) Kundrak, Janos; Deszpoth, Istvan; Molnar, ViktorIn this study the applicability of hard turning is analyzed in the case of disc-shaped parts (gear wheels). The relevance of such parts has been increasing in the automotive industry; therefore, the efficiency of large series or mass production has high priority. The novelty of this paper is the collection of factors that has to be considered in preparation for applicability decisions of hard turning in order to ensure efficient machining. This can be the basis of the IT support, i.e. an automation solution for technologists. The introduced process is elaborated on the basis of theoretical considerations and production shop-floor experience.Документ Designation of evaluation area in measuring 3D surface roughness(Національний технічний університет "Харківський політехнічний інститут", 2020) Molnar, ViktorIn the automotive industry surface topography is an important issue. The working surfaces of the components require high precision machining. In this paper the minimum 3D roughness evaluation areas were determined to decrease the time and cost of measuring the components.Документ Increasing productivity of combined procedure by reducing grinding allowance(Національний технічний університет "Харківський політехнічний інститут", 2019) Kundrak, Janos; Deszpoth, Istvan; Molnar, ViktorExperiments were carried out to determine the minimal extent of acceptable grinding allowance on case-hardened workpieces machined by combined procedure. The extent of acceptable or unacceptable allowance was determined by a “painting” method. After bore grinding tests for 2D roughness, roundness and 3D topography measurement were carried out. It was found that a 0.03 mm allowance in the bores of gearbox wheels of cars is satisfactory and also necessary to obtain the required level of topography when combined machining was applied and when no white layer formed in the turning procedure. This is a significant finding, because the usual allowances of 0.05 mm or higher (in many cases significantly higher) can be decreased to 0.33 mm and the machining time of bore grinding can be reduced in proportion to this extent.Документ Joint machining: hard turning and grinding(Національний технічний університет "Харківський політехнічний інститут", 2019) Kundrak, Janos; Molnar, Viktor; Markopoulos, Angelos P.The manufacturing of increasingly complex components and, at the same time, production of parts of superior quality is a growing trend in industry today. This tendency is realized through advanced machining processes that take advantage of the capabilities of the new machine tools, the properties of cutting tools and the advancements in control and CAD/CAM/CAE systems available today. However, productivity is important and it is not always possible to reduce machining times, while difficult-to-cut materials, successive processes and tool replacements hinder the desired goal. However, ready-machining of the components is a feasible way to achieve the aforementioned requirements. A possibility for this is machining the workpieces on one machine tool, with only one clamping. The fulfilment of the processing and finishing of parts with one clamping and the application of several processes, i.e. hard turning and grinding, in one machine tool is called joint or combined machining. There are several advantages to this arrangement in manufacturing processes, which are discussed in this paper.Документ Lead time reduction in manufacturing process of toothed parts(Національний технічний університет "Харківський політехнічний інститут", 2019) Molnar, Viktor; Deszpoth, Istvan; Kundrak, JanosIn manufacturing automotive industrial components, the reduction of machining time and operation spare time detected in the cutting operations can be realized by the modification of technological parameters. However, reduction in the total component manufacturing lead time can be realized to a great extent by re-organization of the production process to eliminate unnecessary waiting periods (e.g. storage, in-process storage, etc.). In our study the total lead times of two different types of components were analyzed by mapping the process in a detailed way. The rate of waiting time within the lead time was analyzed; the theoretical and the measured lead times were compared and the effect of operation sequence on lead time was analyzed. Using these calculations and also measurements the problematic operations were identified and suggestions for process improvement were made.Документ Tribology and topography of hard machined surfaces(Національний технічний університет "Харківський політехнічний інститут", 2021) Molnar, ViktorIn machining automotive industrial parts by hard machining procedures, the topographic characteristics of high accuracy surfaces have high importance. In this paper 2D and 3D surface roughness features of gear bores machined by hard turning and grinding are demonstrated. The 3D roughness parameters, which are considered as more exact than the 2D parameters, were compared to the 2D ones, which are used more widely in industrial practice. The analyzed machining procedure versions were ranked based on the topographic parameters determining the tribological (wear and oil-retention capability) characteristics of the different surfaces.Документ Wear resistance of hard turned surfaces(Національний технічний університет "Харківський політехнічний інститут", 2022) Molnar, ViktorThe quality of working surfaces plays an important role in automotive industrial components. One of the main characteristics of such surfaces is their wear resistance. In this study external cylindrical surfaces were analyzed. A Design ofExperiment methodology was applied and hard turning experiments were carried out to analyze the effects of the cutting parameters on the 3D surface roughness values of reduced peak height, skewness and kurtosis. The study confirmed earlier findings that at lower feed the wear resistance is higher based on the analyzed roughness parameters. The cutting speed and the depth-of-cut do not influence these parameter values significantly.