Fatigue Analysis of CVC Type Rolling Mill Rolls. Authors: Yukio Shigaki (CEFET MG) Eduardo Araujo (ESSS)

Transcription

1 Fatigue Analysis of CVC Type Rolling Mill Rolls Authors: Yukio Shigaki (CEFET MG) Eduardo Araujo (ESSS)

2 PRESENTATION TOPICS Introduction Description of the Problem Methodology Conclusion and Next Steps

3 Introduction The Federal Centers of Technological Education (Portuguese: "Centro Federal de Educação Tecnológica", shortened CEFET) are Brazilian educational institutes which are directly linked to the Ministry of Education. They are focused on high school, technical high school and academic degrees linked to technology.

4 Introduction This work is part of a research program in progress by CEFET-MG by the Applied Computational Mechanics Research Group (MeCA)

5 Description of Problem Motivation: More investment and more development in efficient manufacturing equipment has been done due to the increasing demand from different industries for flat steel production, as well as, other rolled products. Among other aspects, one expects to have a steel strip with uniform thickness, as well as, a transversal uniform profile along the length of the strip.

6 Description of the Problem

7 Description of the problem New types of rolling mills have been developed to guarantee flatness and thickness of the product. Among them, the CVC (Continously Variable Crown) rolling rolls were developed by SMS Siemag.

8 Description of the problem Crown of the plate/strip C j : C j h c ' '' ( h h ) j 2 j h c : thickness of the strip at center h j : thichnesses of the strip at position j

9 Description of the Problem

10 Description of the problem Out of flatness:

11 Description of the problem Support rolls bi-directional axial displacement Intermmediate rolls bi-directional axial displacement Working rolls bi-directional axial displacement

12 Description of the problem Simulation may be used to study the behavior of different aspects of working of equipment. This work presents a stress analysis and fatigue life estimation of working rolling roll.

13 Methodology: Finite Element Method

14 Methodology: Finite Element Method

15 Methodology: Finite Element Method Table 1 Dimensions of rolls Working Roll Length (desk) Intermediate Roll Length Intermediate Roll Diameter Support Roll Diameter mm mm 300 mm 800 mm

16 Methodology : Loading Function Loading p depends on the reduction of thickness of strip, roll diameter, material and friction. Equation of Loading Bland-Ford solution

17 Methodology: Iterative Method i One applies a uniformily distributed loading on the working roll; ii Vertical displacement are extracted from the central contact line between working roll and strip; iii Based on this results, the strip profile is generated; iv Assuming a tolerance and a previous iteration, the generated profile (iii) is compared with a previous obtained profile. In case they are equal or differences are within tolerance, a solution is achieved. Otherwise proceed to item v; v One may obtain the thickness reduction in the strip with the profile calculated in (iii); vi Re-calculate rolling loading with this new thickness reduction profile; vii Aplply these loadings (item vi) on the finite element model and proceed to item ii;

18 Methodology: Iterative Method Current model and loading were obtained from [1]. 3 iterations were performed to achieve results. Ansys 14.5 was used to perform the stress analysis. Reduction applied: 4.5 to 3.0 mm Width of the strip: 1500 mm Material of the strip: mild steel

19 Methodology: Iterative Method

20 Methodology: Iterative Method Iteration 1: Vertical displacement on contact center line

21 Methodology: Iterative Method Iteration 2: Vertical displacement on contact center line

22 Methodology: Iterative Method Iteration 3: Vertical displacement on contact center line

23 Methodology: Iterative Method Iteration 3: Equivalent Stresses

24 Methodology: Iterative Method Iteration 3: Equivalent Stress of Working Roll

25 Methodology: Iterative Method Iteration 3: Y Displacements

26 Methodology: Iterative Method Fast convergence of the model:

27 Fatigue Analysis A Fatigue analysis was performed regarding: Stresses and Strain from structural analysis 3rd Interaction Material of the rolls: steel with UTS 400 MPa (steel) Geometry: BUR_roll and CVC_roll were included in the analysis Loading: constant amplitude loading. It corresponds to one complete rotation of the roll. S-N method was used to estimate life

28 S-N Curve UTS 400 MPa Extracted from ncode Material Library

29 E-N Curve UTS 400 MPa Extracted from ncode Material Library

30 Fatigue Analysis : Ansys Design Life Model

31 Fatigue Analysis: Estimated Life

32 Fatigue Analysis: Estimated Life

33 Conclusions and Next Step Estimated Life is Infinite Next steps: One can include a notch or a chamfer in the roll. The presence of a notch will reduce the life of the roll. Apply other shifts on the work roll Compare with industrial results

34 References [1] Yukio Shigaki DESENVOLVIMENTO DE UM MODELO MATEMÁTICO-NUMÉRICO PARA SIMULAÇÃO DE LAMINADORES DE PRODUTOS PLANOS COM CILINDROS COM PERFIS CVC Presentation performed on 49º Rolling Seminar Processes, Rolled and Coated Products (2012) [2] ncode - DesignLife Worked Examples: 3 AN-NC-DL-WE HBM UK Ltd [3] Ginzburg,V. Azzam, M. Selection of optimum strip profile and flatness technology for rolling mills

35 Used Software 1. Ansys Mechanical Design Life - GlyphWorks V8.0 ISR3 Release Build 125

36 Aknowledgment The authors thank the support from CEFET-MG and ESSS.

37 OBRIGADO!! THANK YOU