Similateur

Similateur

• 1.
  ArcelorMittal Research June2008 Optimization of lubrication and cooling in cold rolling from 17 mars to 12 September 2008 - RFCS Optcoolub - Tutor: NGO Quang Tien Project leader : Nicolas LEGRAND
• 2.
  Presentation Name : BOULECHFAR Kamal Age: 26 Nationality : Moroccan. Engineering school: Polytechnic School of the University of Orleans - Polytech’Orléans. “numerical simulation of mechanics “ Graduation : DUT Thermal-Energy Engineering. My aim objective : Researches engineer in energetic-mechanics.
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  Internship : Background This internship is carried out under the project Optcoolub Optimize cooling systems in cold rolling in order to reduce water consumption. Make better lubrication on cold rolling mills
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  Internship : involvement Analysis and optimization of lubrication and cooling system in cold rolling The second aim is: Study of 13 roll cooling trials to understand cooling mechanism in roll and strip ( HTC, Flux, T°).  Brno collaboration. Propose an optimum mill cooling configuration and confirm by pilot trials ARsa. The primary aim is : Developing / completing a modeling of cooling system : simulator Avilès HTCs ( coolant-strip and coolant-roll ) Rheology Identify actions increasing the efficiency of cooling
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  The primary aim: Developing / completing a modeling cooling system : simulator Avilès 1) HTCs 2) Rheology
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  Thermal simulator: HTC(x) strip-coolant Advantage: It takes into account: the parameters: , and  f ( T ) influence of speed V Improvement  H eat T ransfer C oefficient of strip-coolant interface along mill interstand Current situation Weakness: It does not take into account: Strip temperature The water flow “explicitly”.  Not Adapted for high temperatures of strip Forced convection:
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  Thermal simulator : HTC(x)  What happen in a high strip temperature “Typically Ts >100°C at least “ ? Problem the material-coolant interface: vapor ,HTC The first appearance of bubbles promotes the exchange of heat. Higher the temperature higher the agitation of water “convection" 20°C 300°C
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  Thermal simulator: HTC(x) Improvement When T°<100°  : natural convection When T°>100°  : Hodgson model Weakness: “ to verify” It does not take into account: influence of speed V Advantage: It takes into account: Strip temperature The water flow . example of strip temperature evolution
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  Thermal simulator: Rheology Current situation Strip heat transfers in the roll bite: strip plastic yield stress We use the SMATCH law  Weakness: “ to verify” Does not take into account The strain rate Temperature Plastic deformation Frictional heat Heat conduction
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  Thermal simulator: Rheology Problem : the graphics show that strip rheology depends on the strain rate We made those experiences for 3 steel grades of AVILES.  To validate the LUCY-BALISTIK model. Influence of speed Our experiment Influence of temperature Literature data
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  Thermal simulator: Rheology Advantage  predicting precisely the evolution of metal hardness along the rolling mill Improvement  Integrate LUCY-BALISYIK model in our simulator:
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  Second aim is: Study of 13 roll cooling trials to understand cooling mechanism in roll and strip ( HTC, Flux, T°). Propose an optimized mill cooling configuration and confirm by pilot trials ARsa.
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  Conditions defined forrealization at stand #4 of Aviles TDM2 Brno has characterized 13 roll cooling configurations for Optcoolub project
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  Method of operatingresults Heat flux variation as a function of time A specific program was developed to extract Flux and temperature measured under the direct spray during the tests. Time Temperature study area
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  AV13-4 Evolution ofFlux and HTC with a temperature of the cylinder HTC mesuré et HTC Loi en fonction de la température moyenne de surface de cylindre 0 5000 10000 15000 20000 25000 0 50 100 150 200 250 300 Température moyenne de surface cyl °C HTC ( w / m ² K ) HTCmoy w / m ² K Flux dependency to roll surface temperature is higher
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  Results withour analysis Results with Brno analysis ±500 : 13- 12- 8- 6 - 11 HTC average for each configuration “ position 4” at T water = 0°c Results obtained with Brno analysis Results with Brno analysis ±200 : 13- 6- 8- 12 - 9 Configuration common among all tests: 13-6-12 HTC average for each configuration
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  If we usethe flux as an indicator of the efficiency of cooling, somme differences in the classification are obtained (compared to classification with HTC) However, we can conclud that config. N°6 is a good configuration as already concluded by Brno Average flux for each configuration 0 200 400 600 800 1000 1200 1400 1600 1800 Flux moy (w/m²) AV4-1 AV4-2 AV4-3 AV4-4 AV4-5 AV4-6 AV4-7 AV4-8 AV4-9 AV4-10 AV4-11 AV4-12 AV4-13 Mean heat Flux for each test. Sensor n°4 Phi moyenne
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  N°13 Uniformity ofHTC with distribution of flow Conclusions : globally, when the flow is strongly heterogeneous, the HTC seems heterogeneous also, but HTC does not follow irregularities of the flow HTC w/m²°C
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  Conclusion 1 er aim : thermal simulator Improvement of inter-stand heat transfer model The rheology experiments have been done 2 nd aim : optimized mill cooling configuration Analysis of 13 roll cooling trials. Experiment planning has been done.
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  In Progress…….. Achievementof simulator The second aim: # To find out an optimized mill cooling configuration “pilot experiment” .  Comparison of 6 roll cooling configurations: 1test with HTRC 6 test with nozzles The test plan : ready Monitoring and analysis of tests : begin next week Synthesis of testes and conclusion: next weeks