Post on 26-Jul-2020
Coupled experimental-numerical analysis of wear
in hot-rolling rolls
L.G.D.B.S. Lima(1), A. Gonçalves(2), A.P.V. Braga(2), R.M. Souza(1), M. Boccalini Jr. (2)
(1) Surface Phenomena Laboratory, Department of Mechanical Engineering, Polytechnic School, University of São Paulo, Brazil (LFS-USP)
2 Institute for Technological Research, São Paulo, Brazil (IPT)
lima.luiz@usp.br
10th International TOOL Conference 2016 - 05/10/2016
Motivation
Project: Advanced system for design of alloys for hot forming tools
Partnership:
Support:
Scope: Development of a numerical system to allow alloy selection based on analysis of damage on micro scales.
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
FORGING ROLLING INJECTION
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Summary
Specific objectives: development of a numerical subsystem capable of predicting wear in hot rolling
based on general process parameters and material modeling
In this presentation:
• Description of the pilot scale mill in operation
• Description of the numerical model developed to reproduce pilot scale rolling
• Comments on preliminary results and improvement of the models
• Discussion of current results
• Next steps in this subject
• Main conclusions
310th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Experimental setup – pilot scale mill
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Experimental setup – pilot scale mill
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Experimental setup – pilot scale mill
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Experimental setup – pilot scale mill
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Instrumented, pilot-scale mill
Roll data:
–AISI H13, quenched and tempered to 46 HRC
–Dimensions (mm): Ø 126.77 x 203 (working region)
–Angular velocity: 27 RPM
Slab data:
–AISI 1045
–Dimensions (mm): 19.05 (thickness) x 92 x 280
– Initial temperature: 1300ºC
Process data:
–5 passes, alternate
–Reduction per pass: 15%
–Time between sucessive slabs: ~ 120 seconds
–Alternate cooling, always on exit side, water
–No descaling
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Experimental setup – pilot scale mill
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Measurements:
• Rolling loads (load cells)
• Temperature (thermocouples on surface and at several depths)
• Wear (roll profile after rolling campaings)
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Numerical model
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Software ABAQUS/Explicit
• 2D, plane strain conditions (central cross-section)
• Thermal and mechanical results, coupled
• Roll material data measured
• Slab material data obtained from manufacturer and literature
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Numerical model
Wear estimation:
• During each time increment of the numerical analysis, wear is calculated locally, based on a
modified Archard equation:
Where
• dt is the local thickness of material removed
• k is the adimensional wear coefficient
• p is the local contact pressure
• dl is the local sliding between roll and slab
• H(T) is the roll hardness, function of local roll temperature
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Numerical model
Wear estimation:
• The local values for each time increment are integrated over the whole slab rolling, resulting in wear
thicknesses per slab rolled, for every position in the roll surface
• As it is impracticable to perform a simulation covering the whole experiment (~1600 slabs), wear is
calculated on a group of slabs basis – values for a single slab are multiplied by a given number of
slabs.
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Wear ismultiplied by N slabs
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Preliminary results - temperatures
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Numerical Experimental
1st rolling pass
Preliminary results – rolling loads
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
1st pass2nd pass
3rd pass
4th pass5th pass
Numerically calculated temperatures and forces are in accordance with measured values. However...
Preliminary results – wear
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Measured Comparison
... values obtained by the numerical models are far higher than the measured in the roll, demanding
further investigation.
Improved model
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Wear coefficient is not a constant k = k(P,N)
Solution Investigation of wear evolution in a reciprocating machine with different normal loads
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Current results
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
Numerical procedure for wear shown before updated with values of k
Results:
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Next steps
• Correction of slab properties to fine tune rolling loads:
• Incorporation of other wear mechanisms apart from abrasion:
– Thermal fatigue
– Adhesion
– Oxidation
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br
Conclusions
• Good results were obtained using a local approach for wear calculation in hot rolling using numerical
models.
• This strategy also allows the identification of the wear intensity in different moments of the process.
• Selection of wear coefficient is critical to the accuracy of the procedure.
• Results are closer for the first group of slabs, after which other mechanisms seem to compete with
abrasion in damaging the rolls.
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Motivation > Summary > Experimental setup > Numerical model > Preliminary results > Improved model > Current results > Next steps > Conclusions > End of presentation
10th International TOOL Conference 2016 – 05/10/2016 Luiz Lima – lima.luiz@usp.br