Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming
Abstract
:1. Introduction
2. Experimental
2.1. Development of In-Situ Observation System
2.2. Fabrication of Surface Texturing
2.3. Experimental Conditions
3. Finite Element (FE) Simulation of Contact State
4. FE Based Computational Fluid Dynamics (CFD) Analysis
4.1. Laminar Two-Phase Flow Analysis
4.2. Fluid-Flow Analysis
5. Results
5.1. Contact State Analysis
5.2. In-Situ Observation of Lubricant Flow
5.3. Effect of Micro-Dimple Diameters
5.4. Effect of Lubricant Viscosity
6. Discussion
7. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
List of symbols | ||
b | Pitch | [mm] |
c | Clearance between punch and die | [mm] |
d | Dimple diameter | [mm] |
dp | Punch with | [mm] |
E | Elastic modulus | [GPa] |
hd | Dimple depth | [mm] |
hl | Lubricant film thickness | [μm] |
hs | Maximum stroke | [mm] |
lc | Contact length | [mm] |
np | Number of forming processes | (dimensionless) |
pc | Contact pressure | [MPa] |
rd | Bending die radius | [mm] |
rp | Punch radius | [mm] |
t | Work sheet thickness | [mm] |
T | Temperature | [˚C] |
u | Kinematic viscosity | [mm2/s] |
vp | Punch velocity | [mm/s] |
vw | Sliding wall velocity | [mm/s] |
vf | Flow velocity | [mm/s] |
Vd | Volume of dimple cell | [mm3] |
Vl | Volume of lubricant at pitch area | [mm3] |
w | Width of die gap | [mm] |
Greek letters | ||
µ | Friction coefficient | (dimensionless) |
η | Kinematic viscosity of lubricant | [mm2/s] |
ηlub | Lubricant viscosity | [Pa·s] |
ηgas | Gas viscosity | [Pa·s] |
λ | Dimple aspect ratio | (dimensionless) |
ρ | Mass density of fluid | [kg/m3] |
ρgas | Gas density | [kg/m3] |
ρliquid | Liquid density | [kg/m3] |
ρd | Texture density ratio | (dimensionless) |
σ | Surface tension coefficient | [mN/m] |
σy | Yield stress | [MPa] |
ν | Poisson’s ratio | (dimensionless) |
θ | Contact angle | [degree] |
φ | Level set function | (dimensionless) |
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Texture Density ρd | Aspect Ratio λ | Diameter d [mm] | Depth hd [mm] | Pitch b [mm] |
---|---|---|---|---|
0.1 | 0.1 | 0.1 | 0.01 | 0.18 |
0.1 | 0.1 | 0.05 | 0.005 | 0.09 |
0.1 | 0.1 | 0.01 | 0.001 | 0.02 |
Work Material | Stainless Steel | (JIS:SUS304-H) |
---|---|---|
Sheet thickness t | [mm] | 0.1 |
Bending die radius rd | [mm] | 0.5 |
Punch corner radius rp | [mm] | 0.5 |
Clearance c | [mm] | 0.09 |
Maximum stroke hs | [mm] | 4 |
Punch Velocity vp | [mm/s] | 50 |
Lubricant viscosity η | [mm2/s] | 1.27, 2.53, 4.51 |
Material | Stainless Steel | Silica Glass Die | Tool Steel Die | (JIS:SUS304-H) |
---|---|---|---|---|
Material model | Elasto-plastic body | Elastic body | Elastic body | |
Mass density ρ | [g/cm3] | 7.93 | 2.2 | 7.72 |
Elastic modulus E | [GPa] | 200 | 72 | 206 |
Yield stress σy | [MPa] | 1170 | - | - |
Poisson’s ratio ν | 0.3 | 0.17 | 0.3 |
Mass Density of Lubricant ρliquid | [kg/m3] | 899.8 |
Lubricant viscosity of ηlub | [Pa·s] | 0.04 |
Sliding speed vw | [mm/s] | 50 |
Flow velocity vf | [mm/s] | 50 |
Lubricant film thickness hl | [µm] | 2 |
Density of gas ρgas | [kg/m3] | 1.2 |
Viscosity of gas ηgas | [Pa·s] | 1.8 × 10−5 |
Atmosphere temperature T | [K] | 293.15 |
Contact angle θ | [degrees] | 20 |
Mass Density ρ | [kg/m3] | 899.8 |
Viscosity ηl | [Pa·s] | 0.04 |
Sliding speed vw | [mm/s] | 50 |
Lubricant film thickness hl | [µm] | 0.5, 1, 2 |
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Shimizu, T.; Kobayashi, H.; Vorholt, J.; Yang, M. Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming. Metals 2019, 9, 917. https://doi.org/10.3390/met9090917
Shimizu T, Kobayashi H, Vorholt J, Yang M. Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming. Metals. 2019; 9(9):917. https://doi.org/10.3390/met9090917
Chicago/Turabian StyleShimizu, Tetsuhide, Hiroyuki Kobayashi, Jochen Vorholt, and Ming Yang. 2019. "Lubrication Analysis of Micro-Dimple Textured Die Surface by Direct Observation of Contact Interface in Sheet Metal Forming" Metals 9, no. 9: 917. https://doi.org/10.3390/met9090917