Papers by Keyword: Energy Parameters

Abstract: The results of the development and manufacturing of a unique research complex for investigating fast-flowing processes of heat and mass transfer during arc welding with a melting electrode are presented. The advantages of the developed complex over traditionally used ones are shown using cinema and video cameras by shadowing the image of heat and mass transfer of a metal. Studies of fast processes using high-speed video recording require powerful backlighting, such as a scattered laser beam, which enhances the visualization of the observed object, namely, the process of melting and transferring each electrode metal droplet under conditions of intense light emission from the electric arc. The article contains explanatory diagrams, control algorithms, video frames of a separate welding microcycle, and examples of recorded oscillograms and the graphical representations of the changes in their quantitative values.

Abstract: The features of the formation of the structure and physical and mechanical properties of all-in-one compounds of low-alloy steels are studied. It is shown that the quality and strength properties of permanent joints depend on the energy parameters of the technological process of their manufacture. The technological process is accompanied by melting, transfer and crystallization of the weld metal from the melt, which has a dominant effect on the structure, indicators of static and dynamic strength of welded joints. The ranges of welding modes that have the greatest impact on the structural and mechanical properties of the zone of permanent joints in the temperature range from +20 degrees to minus 60 degrees Celsius. The results of the research can be widely used in the practice of repair and installation works of structures of the Northern design, working in conditions of naturally low climatic temperatures.

Abstract: The paper presents results of experimental studies on the effect of non-uniform temperature distribution over the metallic charge length on the energy parameters change during round bars rolling process. Experimental tests were conducted on the D370 Continuous Shape Mill in industrial works. From the tests carried out, it has been found that the main cause of occurrence of the non-uniform distribution of temperature over the charge length is the process of heating the metallic charge in the walking beam furnace. During rolling of bars from metallic charge with non-uniform temperature distribution over its length, changes in friction conditions in the zone of contact between the band and the rolls and in the plastic properties of steel being rolled occur. For decrease temperature during metallic charge rolling process about 100 °C (Fig. 2) in walking beam furnace, increase of rolling torque and total rolling power about 30% during rolling process metallic charge in first continuous shape mill stand was observed.

Abstract: The paper presents the results of the theoretical analysis of the asymmetric plate rolling process conducted in the plate finishing mill. The purpose of the work was to determine the influence of working rolls velocity asymmetry on the value and direction of the bending radius of strip flowing out from the deformation zone. The variable parameters of the process were: rotational speed asymmetry factor, a_v ; strip shape factor, h₀/D; and cross-sectional area reduction ε. For the theoretical study, a commercial computer program, FORGE 2008^®, was employed. Working rolls of a diameter of 1100 mm and a constant lower working roll rotational speed of n = 80 rpm were assumed for the study. The asymmetric rolling process was achieved by varying the rotational speed of the upper roll, which was lower than that of the lower roll. The range of variation of the roll rotational speed asymmetry factor, a_v, was 1.01÷1.20. On the basis of the conducted theoretical analysis, the influence of the speed asymmetry factor (a_v = 1.00÷1.20) on plate curvature upon exit from the deformation zone was determined, and the distributions of strip velocity.

Abstract: The paper presents results of theoretical and experimental studies on the influence of strip temperature reduction at the final stage of the normalizing rolling process in a continuous bar rolling mill on the energy and force parameters. The studies were carried out for 38 mm-diameter round bars of constructional steel S355J2G3 (St52-3 acc. to DIN). At the first stage, numerical modelling of the rolling process was performed for the conditions of the currently used rolling technology. The aim of this stage of the work was to determine the distribution of strip temperature during the rolling process and of strip temperature after the rolling process. The obtained computation results were compared with the measurement results recorded during the actual rolling process using a thermovision camera. A computer program designed for three-dimensional modelling of metal flow during rolling in passes was used for the determination of the distribution of strip temperature during rolling. The second stage of the studies included modelling of the bar rolling technology modified by applying normalizing rolling after introducing accelerated strip cooling at the final stage of rolling. The aim of this stage of the work was to establish the influence of reduced strip temperature on the change in the values of the energy and force parameters of the process. By comparing the computed values of rolling power with those of the permissible power it was found that these values were lower than the permissible power of the rolling machine’s main drives installed in the Rolling Mill under analysis. Thus, it was demonstrated that it was possible to implement the process of normalizing rolling in the conditions of the Shape Mill under study.