Wyniki 1-5 spośród 5 dla zapytania: authorDesc:"RÓBERT SOBOTA"

Verification of bulk metal forming numerical model

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Numerical models of metal forming based on finite elements method can lead to excellent results, but it is necessary to verify them by experimental results. The simple way as to verify numerical result is to compare them with experimental result. Bulk forming leads to grain boundaries deformation. The value of strain is very simple to obtain by stereology, more precisely - by measurement of grai[...]

Evaluation of drawing dies wear

  The experiments with pressure drawing dies were carried out on the industrial straight line continuous drawing machine. The steel wires of 2.1 mm in diameter and carbon content of 0.85÷0.87 % were drawn from the wire rod of 5.5 mm in diameter, initially subjected to surface tre- atment with borax. The hydrodynamic lubrication was used to increase production effectiveness, improve wire quality and decrease a number of defective products. As a result of the experiment, the wire were achieved with the diameter and the ovality within the required tolerance and the improved surface quality. Moreover, drawing dies wear was observed. The moment of the dies wear was expressed by a dependence of the drawn wire surface roughness on the drawing process duration. It was found out that when hydrodynamic lubrication was used, dies consumption decreased 4.5 times in comparison to consumption of standard dies. Przeprowadzono eksperymenty ciągnienia drutów stalowych o średnicy 2,1 mm i zawartości węgla 0,85÷0,87% z walcówki o średnicy 5,5 mm poddanej wstępnie obróbce powierzchniowej (boraksowaniu). Próby wykonano na przemysłowej ciągarce liniowej z wykorzystaniem ciągadeł ciśnieniowych. Smarowanie hydrodynamiczne zastosowano w celu poprawy efektywności procesu produkcyjnego, poprawy jakości drutu i zmniejszenia ilości wybraków. W wyniku eksperymentu uzyskano drut o średnicy i owalizacji mieszczących się w granicach tolerancji oraz o podwyższonej jakości powierzchni. Przeanalizowano również zużywanie się ciągadeł. Moment zużycia się narzędzi wyrażono zależnością chropowatości powierzchni drutu od czasu trwania procesu ciągnienia. Próby wykazały, że podczas ciągnienia z hydromechanicznym smarowaniem zużycie narzędzi jest 4,5 razy mniejsze niż zużycie ciągadeł konwencjonalnych. Key words: wire drawing, dies consumption, hydrodynamic lubrication, straight-line drawing machine, surface roughness Słowa kluczowe: ciągnienie drutu, zużycie narzędzi, smarowanie hydro[...]

The Research of Forgeability of Magnesium Alloy at Warm Forming Temperatures DOI:10.15199/24.2016.9.8

  Badania podatności do kucia stopów magnezu w podwyższonych temperaturach The presented contribution is aimed at research of temperature influence on workability of a selected magnesium alloy at temperature interval for warm forming. The magnesium alloy type AZ31 was selected for experimental purposes. The mentioned alloy is used for production of drop forgings. In order to consider forgeability, Židek´s pressure test at warm conditions was selected and used as technological test. The author of mentioned test recommends cylinder shaped test sample with four notches. For magnesium alloy AZ31 hot forming at temperature interval from 250°C to 425°C is recommended. The pressure tests were conducted within the temperature interval of 200-350°C, i. e. at temperatures belonging to lower limit of recommended temperature interval, in order to acquire as much information as possible on behaviour, plasticity and formability of magnesium alloy at lower forming temperatures. Zakres niniejszej pracy dotyczy wpływu temperatury na kowalność stopów magnezu. Wybrany do badań Stop AZ31 jest kształtowany w procesach kucia, czego efektem jest wytwarzanie odkuwek o zróżnicowanych kształtach. Biorąc pod uwagę kowalność do badań, wybrano metodę testu ciśnieniowego w podwyższonej temperaturze. Autorzy tej metody zalecają badania próbek w kształcie walca z czterema karbami. Dla badanego stopu zaleca się temperaturę obróbki plastycznej w przedziale 250°C do 425°C. Test ciśnieniowy przeprowadzono w zakresie temperatury od 200-350 °C, ze względu na analizę zachowania się stopu podczas kształtowania w temperaturze z dolnego zalecanego zakresu przeróbki plastycznej. Key words: warm forming, forgeability, test pressure, magnesium alloy, appearance of cracks in notches Słowa kluczowe: kształtowanie w podwyższonej temperaturze, podatność do kucia, test ciśnieniowy, stopy magnezu, pękanie w karbie Introduction. Drop forgings made of nonferrous metals have been increasingly app[...]

The Influence of Temperature and Strain Rate on Flow Stress of Steel 10CrMo9-10 used for Drawing of Tubes DOI:10.15199/24.2017.8.20

  Introduction. The flow stress curves built by the tensile or pressure tests are important for accurate calculation of forming pressures, forming forces and deformation work in individual moulding operations. The calculated techno lection of suitable forming machines as well as the proper dimensioning of the forming tools. The flow stress curves of the refractory materials su itable for seamless tubes are important for the preparatory phase of computer simulation of the cold drawing process. Correctly selected input parameters of the cold drawing of pipes affect the accuracy of the computer simulation results. It is therefore necessary to constantly complement the si mulation software database of materials with the flow stress curves of the materials used for the production of seamless tubes. Determination of the courses of flow stress curves also allows defining the limit strain by using the Ludwik -Holomon equation [1-4]. Examined material description. Creep-resistant 15 313 steel (10CrMo9-10, W. Nr. 1.7380) is a low-alloy steel cha racterized by both good hot forming and workability. The steel is designed for elevated temperatures at simultaneous higher pressures. It exhibits resis[...]

Research of the dual phase steel DP450 properties from the forming aspects DOI:10.15199/24.2019.1.3

  Introduction. Automotive industry has significant sha􀀐 re on worldwide industrial production. Significantly con􀀐 tributes to research and development of new materials, development of new production methods and production operations. One of steel types developed and used especial􀀐 ly in automotive industry are dual phase steels. Because of this the paper studies plasticity and formability DP 450 dual phase steel with focus on processing by drawing. This steel is used for example for pillar lining and front fender pro􀀐 duction for C3 Picasso car [1, 2]. Studied material. The material DP 450 is dual phase steel, galvanized and cold rolled with thickness s = 1.17 mm. Chemical composition of the steel and required me􀀐 chanical properties are in tables 1 and 2. Microstructure analysis and microhardness measurement of studied material. Optical microscopy was used for basic microstructure analysis of metallographically pre􀀐 pared cross cuts of samples from experimental material. NEOPHOT 30 optical microscope was used for analysis. Metallographic preparation of samples consisted from: - sample extraction - from test sheets samples with length of approximately 15 mm were cut from various lo􀀐 cations, - mechanical grinding - by set of metallographic Table 1. Chemical composition of the DP 450 steel, mass % Tablica 1. Skład chemiczny stali DP 450, % mas. C Mn Si P S 0.05 to 0.10 0.05 to 1.60 < 0.40 < 0.04 < 0.015 Al Nb Ti V Cr 0.02 to 0.08 < 0.01 < 0.01 < 0.01 < 0.80 Table 2. Required mechanical properties of the DP 450 steel Tablica 2. Wymagane własności mechaniczne stali DP 450 Yield strength Rp0,2 [MPa] Tensile strength Rm [MP[...]

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