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Numerical Modelling and Analysis of Orthogonal Metal Cutting

Agmell, Mathias LU (2015)
Abstract (Swedish)
Popular Abstract in Swedish

De flesta komponenter som används i vårt samhälle har genomgått en bearbetningsprocess i något skede i sin tillverkningscykel. På grund av detta spelar de ekonomiska aspekterna av bearbetningsprocessen en viktig roll i tillverkningskostnaden. Det finns flera skäl till att utveckla ett rationellt förhållningssätt till skärande bearbetning, såsom att förbättra skärteknik, producerar produkter med förbättrad precision och öka produktionstakten. Ekonomin i skärprocessen har gjort detta område till ett av stor betydelse ur både ingenjörsteknisk och ingenjörsekonomisk synpunkt. På grund av detta har analytiska modeller utvecklats i syfte att uppnå en bättre förståelse om de fenomen som förekommer vid... (More)
Popular Abstract in Swedish

De flesta komponenter som används i vårt samhälle har genomgått en bearbetningsprocess i något skede i sin tillverkningscykel. På grund av detta spelar de ekonomiska aspekterna av bearbetningsprocessen en viktig roll i tillverkningskostnaden. Det finns flera skäl till att utveckla ett rationellt förhållningssätt till skärande bearbetning, såsom att förbättra skärteknik, producerar produkter med förbättrad precision och öka produktionstakten. Ekonomin i skärprocessen har gjort detta område till ett av stor betydelse ur både ingenjörsteknisk och ingenjörsekonomisk synpunkt. På grund av detta har analytiska modeller utvecklats i syfte att uppnå en bättre förståelse om de fenomen som förekommer vid skärande bearbetning, så som Ernst och Mechant skjuvvinkelssamband. Den kontinuerliga utvecklingen av numeriska metoder, såsom finita element metoden tillsammans med mer beräkningskapacitet, ger möjlighet att simulera komplexa fysikaliska fenomen involverade i spånbildningsprocessen vid skärande bearbetning.



Forskningsarbetet som presenteras i denna avhandling behandlar utvecklingen av finita element modeller för simulering av svarvprocessen. Numeriska simuleringar har utförts för att få en ökad förståelse av skärande bearbetningsprocessen. En svårighet med att simulera svarvprocessen numeriskt är att den metod som använts här, bygger på att man delar in den geometri som skall analyseras i små element. Dessa element kommer sedan att deformeras eller utsättas för en stor elementförvridning vilket kommer leda till numeriska komplikationer. På grund av detta har två olika formuleringar andvänts den ena bygger på att materialet flödar genom ett fast elementnät på så sätt kringgås helt problematiken med elementförvridningen. Den andra formuleringen bygger på att elementnätet är kopplat till materialet och elementen förvrids när materialet deformeras, här motverkas problematiken med elementförvridningen genom att man uppdaterar elementen kontinuerligt i syfte att minska nätets förvridning. De numeriska modellerna presenterade här kan simulera en mångfald av processparametrar. Med arbetsstycket i fokus har följande processegenskaper studerats; spånbildning, skärkrafter, temperaturfördelning, deformationszoner, ytdeformation och minimal spåntjocklek. Den effekt skärverktygets mikrogeometri har på den maximala huvudspänningen, kraftfördelningen och den maximala effektiva spänningen i skärverktyget har också studerats. Flytspänningsmodellen som används under detta forskningsarbete är så kallade Johnson-Cook modellen. En invers analys har utförts i syfte att förbättra och förutse nya konstanter för denna flytspänningsmodell. Detta uppnås genom att först hitta en koppling mellan experimentellt bestämda parametrar från skärprocessen och konstanterna i flytspänningsmodellen. (Less)
Abstract
Most components in use in our society have undergone a machining process at some stage within its manufacturing cycle. As a result, the economics of the machining process plays an important role in the manufacturing costs. There are several reasons for developing a rational approach to material removal, such as improving cutting techniques, producing products with enhanced precision, and increasing the rate of production. The economics of the cutting process has made this area one of great importance from both the technical and the engineering economics points of view. As a result analytical models have been developed in order to achieve a better understanding about the phenomena occurring in the cutting process such as Ernst and Mechant... (More)
Most components in use in our society have undergone a machining process at some stage within its manufacturing cycle. As a result, the economics of the machining process plays an important role in the manufacturing costs. There are several reasons for developing a rational approach to material removal, such as improving cutting techniques, producing products with enhanced precision, and increasing the rate of production. The economics of the cutting process has made this area one of great importance from both the technical and the engineering economics points of view. As a result analytical models have been developed in order to achieve a better understanding about the phenomena occurring in the cutting process such as Ernst and Mechant shear angle relationship. Continuous development of numerical methods, such as the finite element method together with more computing power, gives the potential to simulate the complex physical phenomena involved in the chip formation of a cutting process.



The research work presented in this dissertation concerns the development of finite element models of the turning process. The finite element method has been used to gain better understanding of the cutting process. Both the updated Lagrangian- and the arbitrary Lagrangian-Eulerian formulation have been applied. For the time integration both the explicit and implicit time scheme have been used. The finite element models presented here is able to simulate a diversity of process parameters. Considering the workpiece the following process characteristics are investigated chip formation, cutting forces, temperature distribution, deformation zones, sub-surface deformation, stagnation zone and minimal chip thickness. For the cutting tool the affect micro-geometry has on the maximal principal stress, force distribution and the maximum effective stress is studied. The flow stress model used during this research is the Johnson-Cook model. An inverse analysis has been performed in order to enhance and predict new constants of this flow stress model. This is achieved by experimentally determined parameters from the turning process and then an inverse analysis is conducted by the use of a Kalman filter. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Prof Nicolescu, Mihai, KTH, Royal Institute of Technology, Stockholm
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Metal Cutting, Finite Element Method, Deformation Zones, Sub-surface Deformation, Tool Stress, Inverse Analysis, Kalman Filter, Minimum Chip Thickness
pages
206 pages
publisher
Lund University (Media-Tryck)
defense location
Lecture hall M:E, M-building, Ole Römers väg 1, Lund University, Faculty of Engineering, LTH.
defense date
2015-12-11 10:15
ISBN
978-91-7623-559-1
language
English
LU publication?
yes
id
d89c2288-4367-4e94-9244-c1dec83fa364 (old id 8169130)
date added to LUP
2015-11-17 08:52:08
date last changed
2016-09-19 08:45:12
@misc{d89c2288-4367-4e94-9244-c1dec83fa364,
  abstract     = {Most components in use in our society have undergone a machining process at some stage within its manufacturing cycle. As a result, the economics of the machining process plays an important role in the manufacturing costs. There are several reasons for developing a rational approach to material removal, such as improving cutting techniques, producing products with enhanced precision, and increasing the rate of production. The economics of the cutting process has made this area one of great importance from both the technical and the engineering economics points of view. As a result analytical models have been developed in order to achieve a better understanding about the phenomena occurring in the cutting process such as Ernst and Mechant shear angle relationship. Continuous development of numerical methods, such as the finite element method together with more computing power, gives the potential to simulate the complex physical phenomena involved in the chip formation of a cutting process. <br/><br>
<br/><br>
The research work presented in this dissertation concerns the development of finite element models of the turning process. The finite element method has been used to gain better understanding of the cutting process. Both the updated Lagrangian- and the arbitrary Lagrangian-Eulerian formulation have been applied. For the time integration both the explicit and implicit time scheme have been used. The finite element models presented here is able to simulate a diversity of process parameters. Considering the workpiece the following process characteristics are investigated chip formation, cutting forces, temperature distribution, deformation zones, sub-surface deformation, stagnation zone and minimal chip thickness. For the cutting tool the affect micro-geometry has on the maximal principal stress, force distribution and the maximum effective stress is studied. The flow stress model used during this research is the Johnson-Cook model. An inverse analysis has been performed in order to enhance and predict new constants of this flow stress model. This is achieved by experimentally determined parameters from the turning process and then an inverse analysis is conducted by the use of a Kalman filter.},
  author       = {Agmell, Mathias},
  isbn         = {978-91-7623-559-1},
  keyword      = {Metal Cutting,Finite Element Method,Deformation Zones,Sub-surface Deformation,Tool Stress,Inverse Analysis,Kalman Filter,Minimum Chip Thickness},
  language     = {eng},
  pages        = {206},
  publisher    = {ARRAY(0x5a6ff68)},
  title        = {Numerical Modelling and Analysis of Orthogonal Metal Cutting},
  year         = {2015},
}