Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Pavol MAŤAŠ"

Analysis of eccentricity hot rolled tubes DOI:10.15199/24.2016.8.16

  Analiza mimośrodowości rur walcowanych na gorąco The production programme of ironworks Železiarne Podbrezová a.s. deals primarily with the production of seamless steel tubes rolled from billets from company’s foundry. This paper deals with the study of the transverse defects causes of tubes, especially eccentricity that is evaluated at each technological node separately. The problem of tube eccentricity is considered as a p rimary factor of geometrical deviation. The current method of eccentricity evaluation has been examined. Part of the paper comes up also with the continuous evaluation of tube eccentricity in real production runs. This evaluation takes place once a month, with 98% of seamless tubes produced with eccentricity not exceeding 5%. Conclusions in this paper are decisive for taking preventive measures for eccentricity to occur and also for fixing the measurement methodology for eccentric tubes. Program produkcji huty Železiarne Podbrezová a.s. obejmuje głównie wytwarzanie rur stalowych bez szwu walcowanych z wlewków pozyskanych z własnej odlewni [...]

The comparison of cooling efficiency of twoo types of nozzles for roll cooling on selected stands in stretch reducing mill DOI:10.15199/24.2018.9.7

  Introduction. Stretch reducing mill (SRW) is a hot rolling mill for manufacturing of seamless tubes. Here, the final tube dimensions and final mechanical properties of hot rolled tubes are achieved after cooling [1-5]. During rolling of tubes in SRW the tubular feedstock (“the hollow") of a moderate length passes several stands with circular or oval rolling gap without using any internal tool. During stretch reducing the diameter and wall thickness of the hollow are changed, depending on the final dimensions. The stretch reducing mill can be used [1-9]: - To extend the production range of tubes of small dimensions, - To produce the tubes with small and medium diameter, - To reduce the production costs. Condition of the rolls in SRW stands are of vital importance for obtaining the final diameter and surface quality of the tube. Thus it is necessary to focus on the surface temperature of the hollow and optimal surface temperature of the rolls. Therefore, decision has been made to optimize the roll cooling process by means of a new set of nozzles with smaller nominal flow rate [1-10]. Methodology and instruments for temperature measurement. When choosing the appropriate methodology of temperature measurement, two basic methods were at our hand: contact and contactless. The contact method proved to be more suitable for measuring the surface temperature of the roll [9-14]. Contactless measurement would be very difficult to use for several reas[...]

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