Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Michal KÁN"

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, [...]

The influence of technological parameters for the manufacture of precision seamless tubes for automotive industry DOI:10.15199/24.2019.8.5

  Introduction. On the basis of the increasing demand of tubes for the automotive industry, which in recent years once with the requested commodities of each company is also Zeleziarne Podbrezová (ZP) market needs for this industry. Due to the very specific and complicated production with the need to observe high standards, whether it is a tolerance of geometric dimensions, or compliance with material properties, it is necessary to ensure, during the production itself, mapping of the entire technological flow. In this paper, we looked at two different technologies of pulling and comparing them in terms of geometric accuracy. The first method consisted of draws on mandrel and the second method being a hollow sinking. In these processes, due to the need to know the parameters affecting the drawing itself, we have measured the temperature of the tube surface just behind the tool working surface. The other parameters analysed were the properties of the material itself, which, both at the input and output, greatly affect the forming process itself. The technically cold drawing process of the tubes is shown in Fig. 1 and consists of several technological nodes. Due to the drawing process, it is necessary to properly set the parameters of these technological nodes, such as heat treatment, which must ensure good formability of the material. It is important to ensure the correct chemical treatment which reduces the coefficient of friction and thus also the actual drawing temperature. Other parameters th[...]

Microstructure aspects and comparison of mechanical properties of cold drawn precision seamless tubes DOI:10.15199/24.2019.8.8

  Introduction. In this paper, we focused on a detailed mapping of the selected cold drawing of tube production technology, which is commonly used in cold-drawn tube factory. Its essential foundation is to emphasize the input material with a view to microstructure and mechanical properties, emphasizing the possibilities of the following forming process. In previous experiments, a methodology for determining intense tensile strength by mechanical properties was proposed. Given the economic and technological savings, it is important to propose adjustments that modify the process while not compromising the microstructural properties of the material, necessary to apply additional limit deformations in the process itself. The whole technological process consists of individual technological nodes (Fig. 1), which must meet the necessary standards resulting from the set technological process. By modifying a specific technological node in this case of the drawing process, it allows for the omission of the entire process, which has an economic benefit and, last but not least, saving time and performance for individual employees. To meet these conditions, it is necessary to observe the conditions of the input material properties (Fig. 2) and this is in our case a rolled tube. This paper describes the first course of selected tube drawing technology in terms of microstructure and mechanical properties. In the first run, the starting material and two consecutive strokes are described without intermediate annealing and subsequent heat treatment [3]. Experimental material. The experimental material was selected on the basis of the ZP production portfolio. Considering the extensive experiments that were conducted to innovate [...]

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