Finite Element Simulation of Induction Hardening in Saw ...
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Finite Element Simulation of Induction Hardening in Saw Blades for Food Processing H. Torres 1 , F.A. Pérez-González 1, , N.F. Garza-Montes-deOca 1, , O. Zapata-Hernández 1, I. Felde 2 , T. Réti 2 , M. Réger 2 and R. Colás 1 1 Universidad Autónoma de Nuevo León 2 Obuda University, Hungary.
Transcript of Finite Element Simulation of Induction Hardening in Saw ...
Finite Element Simulation of Induction Hardening in Saw Blades for Food Processing
H. Torres1, F.A. Pérez-González1,, N.F. Garza-Montes-deOca1,, O. Zapata-Hernández1, I. Felde2, T. Réti2, M. Réger2 and R. Colás1
1Universidad Autónoma de Nuevo León2 Obuda University, Hungary.
• Introduction
• Experimental procedure
• Model preparation
• Results
• Conclusions
• References
• Introducción
• Procedimiento experimental
• Preparación de modelo
• Resultados
• Conclusiones
• Referencias
Optimization of induction hardening process by FEM. SISAMEX, UANL, GH Induction.
Induction hardening patterns prediction by FEM. SISAMEX.
INTRODUCTION
AbstractSaws for food are expected to have a goodresistance wear during service; these arecomponents that are subjected to inductionhardening process. This process offers goodindustrial advantages since heating is done atspecific regions during very short times withoutheating al l volume.
The scope of this work is to simulate inductionhardening processing using Finite Element Method(FEM) to solve heat transfer problem, andBoundary Element Method (BEM) to solveelectromagnetic problem. A coupledelectromagnetic-thermal-structural model wascreated in DEFORM 3D to model heating andquenching stages considering phasetransformation. Altogether to the finite elementsimulation, experimental tests were made to theaim to use the same conditions and validate theresults from FEA and experimental process.
Samples characterisation was carried out by SEMand micro-hardness.
ResumenLas sierras de corte para alimentos soncomponentes los cuales se espera tengan unabuena resistencia al desgaste durante su servicio,estas son sometidas al proceso de endurecimientopor inducción. Este proceso ofrece grandesventajas industriales desde realizar elcalentamiento en zonas especificas durantetiempos muy cortos sin calentar todo el volumen.
EL alcance de este trabajo es realizar la simulacióndel proceso de calentamiento por inducciónutilizando el Metodo de Elemento Finito pararesolver el problema de transferencia de calor, y elMetodo de Elemento Frontera para solucionar elproblema electromagnetico. Un modeloelectromagnetico-térmico-estructural acoplado fuecreado in DEFORM 3D para modelar las etapas decalentamiento y enfriamiento considerando latransformación de fase.
La caracterización de muestras fue realizada pormicroscopia electronica de barrido (SEM) ymicrodureza.
Introduction High carbon steels are used in the manufacture of cutting tools due to its capacity todevelop a high hardness structure made of tempered martensite. Respect to theheat treatment, as well-known, the hardening and tempering process of the steelconsists of the steps of austenitizing, quenching and tempering: the first two arecharacterised by the formation of austenite and its full transformation to hardmartensite, while the third is performed to restore toughness.
Figure 1. Saw blade for food processing.Figure 2. CCT diagram for 0.44 % carbon steel
*Source: After "Einführung in die Werkstoffwissenschaften"; ed. W. Schatt, 7th edition 1991.
Induction hardening
• Some of the advantages ofinduction hardening are: heatingis very fast, it is a very efficientprocess, and it has the ability ofheating locally.
Endurecimiento por inducción
• Algunas de las ventajas delendurecimiento por inducciónrespecto a los tratamientostérmicos tradicionales son:calentamiento rápido, procesoeficiente, tratamiento localizado,entre otras.
Introduction
Figure 3. Induction heating applications
Introduction
Specifications:• Polished high carbon steel• Hardened, ground teeth• Laser-etched blade for easy identification
Meat types:• Meat with bones or boneless,
thawed or frozen• Fish
Saw blades in food processing are tools that are used tocut meat and bones, and they are found in butcheries,slaughter houses, and super markets.
Induction hardened zone
Bone
Figure 4. Saw blades during cut of meat with bones.
Objective• Simulate induction hardening
processing of saw blades usingFinite Element Method (FEM) tosolve heat transfer problem, andBoundary Element Method(BEM) to solve electromagneticproblem.
• Simular el proceso deendurecimento por inducción desierras de corte para alimentosmediante el metodo de elementosfinitos y metodo de condiciones defrontera, con el fin de resolverproblemas de transferencia decalor y electromagneticos,respectivamente.
Objetivo
PhysicalSystem
Model
FEM
Validation
Modify of system
Prediction
Experimental procedureA company of cutting tools for industrial foodapplications provided saws of commercial highcarbon steels. To the aim to improve a goodinduction heat treatment and increase themechanical behaviour of the saw, in specificthe teeth’s was design and manufacture aninduction coil as can be appreciated in Figure5, where is observed the coil and the sawmodelled in a CAD program.
The parameters used for this study are thesame in the simulation and experimentalprocess (voltage was considered to be 8 kVand frequency has a value of 27 MHz,processing time is 13.5 ms) in order tovalidate the simulation with experimentalvalues.
Figure 5. Coil and saw system.
Tooth
Model preparation (FEM)The geometry of the saw was simplifiedsince heat only concentrates on the tooth. Aheight of 5.6 mm, which is 10 times thethickness of the sheet, was considered.General purpose commercial finite elementsprograms are used very frequently to modelinduction hardening processes. These kindof programs offer high capability of handlingcomplex geometries and deal with verycomplex phenomena. Therefore, computersimulation was used to obtain thetemperature distributions on the saw duringinduction hardening process. This was doneusing DEFORM 3D software, as can beobserve in Figure 6. Figure 6. Finite element mesh of the system.
*Note. The total number of elements was 47692and 13389 for saw and coil, respectively
Model preparation (FEM)Boundary conditions are show in Figure 7. The base ofthe saw was fixed and a translational velocity of 1.3m/s was assigned to the coil. It is important to noticethat in the real process the coil is fixed. Assigning thisvelocity to the saw will require a very highcomputational time for the calculation because of theLagrangian formulation for the elements of the saw.The initial temperature of the saw is 20 °C.
Thermal properties for austenite and martensitephases were considered to be temperature dependentand they are shown in Figure 8, where thermalconductivity and specific heat capacity are plotrespect to the temperature for each phase.
Figure 7. Boundary conditions.
Figure 8. a) Thermal conductivity, b) Specific heat of steel.
Model preparation (FEM)Electromagnetic properties for austenite andmartensite phases were considered the same.Electrical resistivity is shown in Figure 9.
For the coil the electrical resistivity and therelative magnetic permeability wereconsidered to be 2.5x10-6 W-m, and 1,respectively. Thermal expansion coefficient wasnot assigned in this model since there was nocalculation of thermal stresses due to phasetransformation although usually are developedduring quenching.
Figure 9. Electrical resistivity of steel.
ResultsIn this figure is possible to observe the temperature distribution on the saw. Themaximum temperature is localized in the tip of tooth (1200 °C), where ismandatory to promote the phase transformation.
Figure 10. Temperature distribution in the saw.
1200
ResultsMeasurement of temperatures during this process is very difficult since in the real processthe saw is moving. In this simulation velocity boundary condition was applied to the coil toreduce computational time.
Figure 11. Temperature evolution during simulation in different regions of the saw.
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ResultsMicrograph of the saw blade after the surface hardening, in this figure is possible to observe atypically gap or layer of phase transformation, where this layer is a fine-grain martensitic onspecific areas of the saw.
Figure 12. Microstructure evolution after heat treatment of the master material.
ResultsMicro-hardness test were carried out on different samples to the aim to measure themechanical properties on the induction-hardening zone of the saw.
Figure 13. Hardness evolution on the saw
Results
Figure 14. a) Finite element simulation of martensite transformation, b) Metallographic examination of the saw.
Phase transformation using the specialized software and micrograph by SEM. In this figure ispossible to observe that the layer or gap of phase transformation on software and micrographis similar, because the layer of fine martensite on tooth are the same for both analyses, but insmall zones this layer by FEM is different respect to micrograph .
~840 µm~860 µm
Conclusions• A coupled electromagnetic-thermal-structural with phase transformation models
packages was successfully implemented. The gap or layer of full phase transformation tomartensite in the material was very similar for both, Finite Element and micrographicanalyses. Using Finite Element Analysis is possible to obtain the optimal parameter todo a good heat treatment, respect to the deep of tempering on the material.
• Distance between coil and sample has to be considered in the design of the process, tothe aim to have an uniformity of the temperature in the material or study zone.Otherwise, the geometry and orientation of the coil respect to the work specimen is veryimportant too, due to these variables have a high consequence in the surface hardeningprocess.
Current process Optimized Process
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