Wyniki 1-10 spośród 14 dla zapytania: authorDesc:"Ľudovít PARILÁK"

The application of PVD coating for tools used at tube straightening

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Straightening is a technology that is used to remove undesirable distortions. Curvature of the product axis arises as a result of the production technology [1]. Straightening leads to the elimination or reduction of curvature in the metal products using external forces. In practice, the tube runs between the straightening rolls that are rotated to the direction of straightening at an angle (Fig. 1). The roll’s profile is not the tube’s radius. The profile is hyperbolic; the contact roll touches the tube at just three points (Fig. 2). The tube rotates as it passes through the straightening machine. While passing through the machine, the tube is subjected to two specific straightening forces: 1. Pressure straightening. Each pair of rolls can be adjusted so that the gap between them is slightly smaller than the outside diameter of the tube. As the tube passes through this restricted gap, it is subjected to pressure which, if sufficient, will cause the tube walls to be strained past their elastic limit, thereby causing some straightening of the tube. If this ability to squeeze the tube is used correctly, the tube will be "rounded up," removing some or all of its ovality (Fig. 3) [2]; 2. Bend, or offset, straightening. One or more pairs of rolls can be adjusted to cause the tube to follow a curved path through the machine (F[...]

Optimalization of tempering parameters for 15313 steel grade DOI:10.15199/24.2015.9.7


  Tube production range in Železiarne Podbrezová involves a wide range of heat resistant steels for high-temperature applications up to 650°C. The tubes produced are being delivered to the customers as rolled and heat treated. Upon the costumer request they could be further processed as precision cold drawn tubes. The aim of our experiment is to provide more precise chemical composition, technological parameters of tube production and optimization of heat treatment. In this paper, results obtained for 15 313 steel grade are presented. This steel grade belongs to the class of heat resistant hot-rolled steels with guaranteed creep resistance up to 560 °C. To meet the required values of strength, plastic- ity, and creep resistance the ferritic-bainitic microstructure is required. In this paper, the influence of heat treatment on the microstructure and mechanical properties is investigated. The result of this analysis is the optimization of microstructure, expressed as a volume fraction of bainite and also a ferritic grain size. This can be linked to optimal conditions for normalizing using rapid quenching and subsequent temper- ing. The presented results allow us to optimize the chemical composition of 15 313 steel grade and the heat treatment parameters so to obtain the optimal ferritic-bainitic microstructure for safe, long-term and trouble-free applications in power industry. Zakres produkcji rur w przedsiębiorstwie 􀃤eleziarne Podbrezová obejmuje szeroki wybór stali żaroodpornych do użytku w wysokich tempe- temperaturach, aż do 650°C. Rury produkowane tutaj są dostarczane do klientów po walcowaniu i obróbce cieplnej. Na życzenie klienta mogą one być poddane dalszej obróbce, takiej jak precyzyjne ciągnienie rur na zimno. Celem naszego eksperymentu jest ustalenie bardziej precyzyjnego składu chemicznego, technologicznych parametrów produkcji rur oraz optymalizacja obróbki cieplnej. Niniejsza praca prezentuje otrzymane rezultaty dla typu [...]

The application of CVD coatings for cold forming tools

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The cold forming tools of axis symmetrical faces are subject to abrasion, and the high demands of cohesive strength of operating surface are required. The paper deals with the possibilities of usage of CVD coatings on chosen tooling materials with the view of lifetime and reliability increase. After the tooling material was chosen the conditions of two-layers coating (TiC +TiN) were optimized[...]

Analysis of deformation in precision seamless tubes during cold drawing DOI:10.15199/24.2015.9.12


  This paper deals with the analysis of deformation in precision seamless tubes during cold drawing. The tubes were cold-drawn in five technological sequences, undergoing seven drawing passes in total. After each sequence the intermediate annealing took place. The main goal of the experiment was to evaluate the initial stage of the drawing process for E235 hot-rolled steel tube in Železiarne Podbrezová tube drawing plant, going from ∅ 31.8 × 2.6 mm to the final dimension of ∅ 6 × 1 mm while using specified reductions according to technological standards. The influence of selected reductions and the drawing technology on deformation of tubes was evaluated. The experiment described in this article is a part of the research project aimed at whether it is possible to determine the input technological parameters so that the resulting effect makes the tube production more effective. W artykule przedstawiono analizę odkształcenia precyzyjnych rur bez szwu podczas ciągnienia na zimno. W ramach pięciu ciągów zrealizowano łącznie 7 przejść. Po każdym ciągu następowało międzyoperacyjne wyżarzanie. Głównym celem eksperymentu była ocena wstępnego etapu procesu ciągnienia rur ze stali E235 w ciągarni rur 􀃤eleziarne Podbrezová. Walcowane na gorąco rury wsadowe w rozmiarze ∅ 31,8 × 2,6 mm ciągnięto do uzyskania końcowego rozmiaru ∅ 6 × 1 mm, stosując wielkości redukcji przekroju w kolejnych przepustach dobrane zgodnie z normami technologicznymi. Dokonano oceny wpływu wybranych wielkości redukcji przekroju i technologii ciągnienia na odkształcenie rur. Eksperyment przedstawiony w artykule jest częścią projektu badawczego, który ma wskazać, czy możliwe jest określenie wejściowych parametrów technologicznych umożliwiających bardziej efektywną produkcję rur. Key words: reduction, tube drawing, plastic deformation Słowa kluczowe: redukcja przekroju, ciągnienie rur, odkształcenie plastyczne.Introduction. Cold drawing technology used f[...]

The Change of Mechanical Properties of Material Using Various Reductions by Cold-Drawn Precision Seamless Tubes DOI:10.15199/24.2016.8.11


  Zmiana właściwości mechanicznych materiału dla różnych etapów redukcji przekroju poprzecznego w procesie ciągnienia na zimno precyzyjnych rur bez szwu The production of cold-drawn precision seamless tubes has an old tradition in Železiarne Podbrezová a.s. The production itself consists as a final operation of two previous operations, namely: steel plant - production of continued casting billet and hot-rolling plant - production of hot-rolled tubes. At steel plant, steel is produced in electric arc furnace with following continuous casting. The final product is biller with dimensions 200 × 200 × 400 mm. At hot-rolling plant, hot-rolled tubes serve as feed stock for cold-drawing. A hot-rolled tube can be adjusted to feed stock of cold-drawing plant from the material as well as from dimensional point of view. Based on these possibilities, technological process of production - number of passes, heat treatment and percentage of reduction can be altered by technologists. In this paper, we dealt with number of operations in technological processes of cold-drawing plant. As we have already mentioned, passes, reductions and heat treatment can influence the final tube in terms of mechanical properties (Rp0,2, Rm, A5, HV) and microstructural states. W hucie Žleziarne Podbrezová[...]

Numerical simulation of cold drawing of multi-rifled seamless steel tubes DOI:10.15199/24.2016.9.1


  Symulacja numeryczna ciągnienia na zimno rur stalowych bez szwu z wewnętrznym żebrowaniem Multi-rifled precision seamless steel tubes are produced by cold drawing technology, utilizing multiple drawing sequences with intermediate heat treatment. In this paper, numerical simulation of multi-rifled tube drawing is compared with the experiment regarding the dimensions of grooves on the inner surface of the tube. For numerical simulation, DEFORM-3D software was utilized. The numerical model considered drawing of a hollow feedstock with dimensions ∅ 36 mm × 8 mm into the multi-rifled tube with dimensions ∅ 28.6 mm × 6.3 mm. The analysed numerical results turned to be consistent with the dimensions of grooves obtained experimentally and measured by optical 3D scanning. Based on the validated model, further optimization of various technological parameters can be made, providing an effective method for enhancing product quality and lowering production costs. Precyzyjne rury bez szwu z wewnętrznym żebrowaniem są wytwarzane w procesie wielooperacyjnego ciągnienia na zimno z międzyoperacyjną obróbką cieplną. W artykule przedstawiono porównanie wymiarów rowków na wewnętrznej powierzchni rury uzyskanych eksperymentalnie z wynikami symulacji numerycznej przeprowadzonej w programie DEFORM 3D. Symulacja została przeprowadzona dla ostatniej operacji procesu ciągnienia rury żebrowanej o wymiarach ∅ 28,6 mm × 6,3 mm z rury o gładkich powierzchniach i wymiarach ∅ 36 mm × 8 mm. Analizowane wyniki symulacji numerycznych okazały się zgodne z wymiarami żeber uzyskanych eksperymentalnie, które zmierzono metodą przestrzennego skanowania optycznego. Zweryfikowany model może być wykorzystany do optymalizacji różnych parametrów technologicznych, stanowiąc efektywną metodę poprawy jakości wyrobów oraz zmniejszenia kosztów produkcji. Key words: seamless steel tube, FEM, numerical simulation, multi-rifled tube, cold drawing Słowa kluczowe: stalowa [...]

The technology of cold drawing of seamless steel tubes using numerical simulation DOI:10.15199/24.2017.8.17


  Introduction. At Zeleziarne Podbrezova a. s. (ZP), the drawing process of precision seamless steel tubes has a long tradition. Already in 1968, the construction of a new tube plant began. The tubes have been produced at ZP by draw􀀐 ing technology since 1971. After long time, this process has undergone great changes. Today, ZP is a major European producer of hot-rolled and cold-drawn seamless steel tubes. At present, it is possible to talk about high-tech technology. The drawing plant is equipped with 14 drawing benches with drawing force from 250 to 1000 kN. These devices enable to produce tubes with dimensions: outer diameter from Ø4 to Ø120 mm, with a wall thickness of 0,5 - 11mm and length from 2 - 16mm. The tubes are drawn to the final dimensions according to the customer´s requirements. For this particular technology, a hot rolled seamless steel tube serves as a feedstock for multiple cold drawing opera􀀐 tions with intermediate heat treatment. The reduction of the outer diameter and wall thickness must be set correctly for every pass. The aim is determine the lowest number passes because of low economy costs. In this technology, drawing with plug and hollow sinking are used. In the first passes, where the outer diameter and wall thickness is reduced, the drawing with the fixed plug is used. The fixed cylindrical or fixed conical plug is utilized depending on the wall thickness of input feedstock. The conical plug enables to use higher drawing velocity thanks to its geometry which provides better flow of material. Hollow sinking is a final process in which the wall thickness stays the same and the outer dimen􀀐 sion is reduced [1-3]. In general, the drawing process is determined by the mate􀀐 rial properties of the tube being drawn, the lubrication, and the tool ge[...]

Measurement of roll temperature in stretch reducing mill DOI:10.15199/24.2017.8.24


  Introduction. During rolling of seamless steel tubes in a stretch reducing mill (SRW) the tubular feedstock passes several 3-roll stands with circular/oval rolling gap without any internal tool. The input feedstock of a mod erate length is usually stretched many-folds, depending on the final tube dimensions [1]. In this paper, we focused on the cooling effect of water sprayed onto the roll sur face during stretch reducing of various tube dimensions. In Železiarne Podbrezová tube rolling plant the thin- -walled tube dimensions appear to be critical for maintain ing sufficiently high rolling exit temperature (Tdov > Ar3). To solve this problem we must first measure the actual temperature of the rolls in order to decide whether there is a margin for further lowering of the water flow rate; too little cooling could be detrimental to the life span of the rolls. For this, two different approaches to temperature mea surement can be adopted. In 2016, roll temperature mea surements were carried out periodically using MICRO-EP SILON thermoME-TER LS portable laser pyrometer (Fig. 2) with spectral sensitivity (8 ÷ 14) μm and 200ms sensing period (time constant of the device is 150 ms). However, we were not measuring the working surface temperature direct ly; the measurements were carried out on the oxidized side surface of the rolls. In addition, test measurements of the glossy working surface of the rolls were performed, too, but the glossy nature of the surface with very small emisivity rendered these measurements unreliable. Next to the con tactless measurement method we also carried out contact measurem[...]

The influence of reduction on the surface temperature in the process of drawing tubes DOI:10.15199/24.2019.8.12


  Introduction. Cold drawing technology used for manufacturing of precision seamless steel tubes in Železiarne Podbrezová depends on many factors, two of which are the initial and the final tube dimensions[1-4]. The proper selection of area reductions is therefore a crucial task as the improper reduction sequence may lead to excessive straining, possibly causing cracks or even material failure[1-3]. In plug drawing technology, the inner diameter of the tube takes the exact dimension while the wall thickness is being reduced. Cold drawing using a fixed plug is a versatile technology, sporting high productivity and relatively low demands on drawing tools. As the main tool, the reducing die is being used[1-3]. A cylindrical plug is inserted into the die orifice, being fixed on a mandrel. The proper alignment of the die and the plug is necessary for attaining correct dimensions of the tube after drawing and also for drawing in general, see Fig. 1 [1-3]. The drawing technology. The process of a tube cold drawing is schematically depicted in Fig. 2. The main production steps are as follows [2-4]: - feedstock pre-processing, - cold and hot pointing of tube ends, - chemical treatment of the tube (pickling, phosphating, lubrication), - cold drawing, [...]

Compare of the Dies and They Influence of Geometry Precision of the Cold Drawing Tubes with Small Dimensions DOI:10.15199/24.2017.8.22


  Introduction. The article deals with production of seam less precision cold drawing tubes drawing without plug and the influence of technological parameters with effect on the mechanical properties of the tubes. The aim of the ex􀀐 periment is to verify the possibility of drawing hot rolled tubes by one pass technology from dimension 18 × 0.9 m with tempering after drawing to dimension 6 × 1 mm by selected reductions which abide by the factory conditions of Železiarne Podbrezová a.s.. At the End of the article is comparison of both of these dies on geometry and mechani cal properties (Rp0.2, Rm, A5.65). Next is the same com parison in software DEFORM 3D. With consideration of specialization on production seamless precision tubes in Železia[...]

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