The Navier-Stokes equation has been solved numerically along with the two equations eddy diffusivity k-e turbulence model in a continuous galvanizing bath of industrial size taking the details of the sink and the guide rolls into account where the strip speed and the width were kept constant. The main objective of the work was to eliminate the vortex formed between the strip and the sink roll, due to the movement of the strip over the sink and the guide rolls. This vortex feeds the dross particles back to the flow again so that the strip could pick up the dross over the time thus spoiling its own quality. Two alternative arrangements of placing a plate baffle (parallel and perpendicular) near the strip were tried, which could eliminate the vortex completely near the strip. The parallel plate baffle could eliminate the vortex as well as the perpendicular plate baffle but the flow field due to the perpendicular plate baffle seems to be more attractive than the one created due to the parallel plate baffle. So the choice of implementation remains with the plant personnel depending on the ease of fitting the plate to the galvanizing/zinc bath.KEY WORDS: flow barrier; vortex removal; galvanizing bath; mathematical model; CFD analysis; dross pickup.width but not with the line speed and the temperature distribution, although uniform in general, to be affected by charging of cold zinc alloy ingots directly into the bath.An extensive work has been done by Ajersch and the group [5][6][7][8] over last ten years to determine the 3-dimensional velocity and temperature fields and to find the effects of various parameters such as line speed, strip width, strip temperature, inductor mixing and ingot addition on them. They have also found that the line speed does not change the global flow pattern but modifies the velocity field in the snout, near the strip, and near the sink and guide rolls. The inductors, when operated at the maximum capacity during ingot melting, have an effect of induced mixing and the density variation due to the thermal effect alter the flow near the inductors and the ingot and never in the entire flow field which is mostly governed by strip motion only. They have also tried to find the transient aluminum distribution in the bath and correlated the results to predict the generation and movement of intermetallic dross particles within certain region in a zinc pot. 8) In physical models studies, Toussaint et al. used an experimental device to determine the circulation pattern of molten zinc whereas others have used scale-down water models with the help of hot-wire anemometry and LDV (Laser Doppler Velocimetry) techniques, 10) and PIV (Particle Image Velocimetry) technique. 11,12) From the literature survey it has been clear that the objective of many researchers has been to study to the flow field inside the galvanizing bath because this probably can give a clue to control dross pick up. The flow field is normally very complicated inside the bath and the movement of the dross particles, which vary possibly fr...
Thermal drilling is a novel sheet-metal-hole-making technique that utilizes the heat produced at the interface of the rotating conical tool and workpiece in order to soften the workpiece and pierce a hole into it. In this work, experiments with thermal drilling of galvanized steel were conducted based on the Taguchi L27 orthogonal array. Significant process parameters such as rotational speed, tool angle and workpiece thickness were varied during the experimentation. In thermal drilling, the thermal-drill tool pushes aside a large amount of workpiece material to form a sleeve, which is often referred to as the bushing length. A predictive model for the bushing length was developed using a feed-forward artificial neural network based on experimental data. As the bushing length is closely associated with the tapping process, the influences of the input process parameters play a vital role in fastening galvanized steel with threaded fasteners in diverse engineering applications. The optimization problem was solved by implementing a genetic algorithm under constraint limits to maximize the bushing length. Further, a confirmation test was conducted with the intention to compare the optimum value and its corresponding bushing length predicted by the genetic algorithm. Good agreement was observed between the predicted and the experimental values. Keywords: thermal drilling, artificial neural network, genetic algorithm, galvanized steel, bushing length Termi~no vrtanje je nova, za vrtanje lukenj v plo~evino, uporabljena tehnika, ki izkori{~a toploto, proizvedeno na povr{ini vrte~e se konice orodja na obdelovancu z namenom, da ga zmeh~a in vanj naredi luknjo. V delu so bili izvedeni preizkusi na osnovi metode Taguchi L27 z ortogonalno matriko s termi~nim vrtanjem galvaniziranega jekla. Pomembni parametri postopka, kot so: hitrost vrtenja, kot orodja in debelina obdelovanca, so se med eksperimentiranjem spreminjali. Pri toplotnem vrtanju, vrtanje orodja potisne stran ve~materiala obdelovanca tako, da se tvori navarek (rokav) okoli luknje, ki se pogosto omenja kot dol`ina {ablone. Napovedni model za dol`ino {ablone, je razvit z uporabo umetne nevronske mre`e, ki temelji na znanstvenih podatkih. Ker je dol`ina {ablone precej povezana s procesom izdelave navoja, vplivi teh vhodnih procesnih parametrov igrajo klju~no vlogo pri pritrditvi galvaniziranega jekla z navojem pritrdilnih elementov v razli~nih in`enirskih aplikacijah. Problem optimizacije je bil re{en z implementacijo genetskega algoritma na podlagi omejitev za pove~anje dol`ine {ablone. Ugotovljeno je bilo dobro ujemanje med napovedano in eksperimentalno vrednostjo. Klju~ne besede: termi~no vrtanje, umetna nevronska mre`a, genetski algoritem, galvanizirano jeklo, dol`ina {ablone
In the present work a three dimensional finite element thermal analysis of friction stir welding has been carried out in Comsol Multiphysics software. In the present model only heat generation due to friction is considered. The thermal profile obtained from the simulation has shown good agreement with the previously published experimental results. Three factors viz. axial force, welding speed and rpm each having three different levels was studied. The optimization of the process parameters for maximum temperature has been carried out by Taguchi method based on Taguchi's L9 orthogonal array. In this approach, each response ie. Temperature is transferred to corresponding signal to noise ratio by using Taguchi's larger the better criterion (LBT). The optimum welding parameters obtained after the analysis are F=5000N, S=80 mm/min and N= 1600 rpm. A conformation test is conducted by using these process parameters. The maximum temperature obtained was 590.62⁰C which is 89.4 % of melting temperature of the material.
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