Inverse evaluation of equivalent contact heat transfer coefficient in hot stamping of boron steel

2016 ◽  
Vol 87 (9-12) ◽  
pp. 2925-2932 ◽  
Author(s):  
Min Wang ◽  
Chun Zhang ◽  
Haifeng Xiao ◽  
Bing Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Stamping ◽  
Boron Steel ◽  
Contact Heat ◽  
Contact Heat Transfer

Development of Estimation Procedure of Contact Heat Transfer Coefficient at the Part–Tool Interface in Hot Stamping Process

2011 ◽  
Vol 32 (6) ◽  
pp. 497-505 ◽  
Author(s):  
Bakri Abdulhay ◽  
Brahim Bourouga ◽  
Christine Dessain ◽  
Gilles Brun ◽  
JoËL Wilsius
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Stamping ◽  
Estimation Procedure ◽  
Contact Heat ◽  
Contact Heat Transfer ◽  
Stamping Process

Augmentation of Direct-Contact Heat Transfer to Drops with an Intermittent Electric Field

1980 ◽  
Vol 102 (1) ◽  
pp. 32-37 ◽  
Author(s):  
N. Kaji ◽  
Y. H. Mori ◽  
Y. Tochitani ◽  
K. Komotori
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Electric Field ◽  
Transfer Coefficient ◽  
Direct Contact ◽  
Silicone Oil ◽  
Duty Ratio ◽  
Contact Heat ◽  
Contact Heat Transfer ◽  
Water Drops

The characteristics of the augmentation technique previously proposed by the authors has been studied experimentally with water drops 3.9 to 5.9 mm in diameter rising in methylphenyl silicone oil. Each drop is subjected to an intermittent electric field applied periodically perpendicular to its trajectory, and the drop responds by periodic elongation in the direction of the field. The dependence of heat transfer coefficient on the strength, frequency and duty ratio of the field is presented and discussed.

High Temperature Heat Transfer During Hot Forming Die Quenching of Boron Steel

2013 ◽  
Author(s):  
Etienne Caron ◽  
Kyle J. Daun ◽  
Mary A. Wells
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling Rate ◽  
Hot Stamping ◽  
High Strength ◽  
Hot Forming ◽  
Boron Steel ◽  
Steel Blank ◽  
Die Quenching

Distributed mechanical properties can be obtained in ultra high strength steel parts formed via hot forming die quenching (HFDQ) by controlling the cooling rate and microstructure evolution during the quenching step. HFDQ experiments with variable cooling rates were conducted by quenching Usibor® 1500P boron steel blanks between dies pre-heated up to 600°C. The heat transfer coefficient (HTC) at the blank / die interface, which is used to determine the blank cooling rate, was evaluated via inverse heat conduction analysis. The HTC was found to increase with die temperature and stamping pressure. This heat transfer coefficient increase was attributed to macroscopic flattening of the boron steel blank as well as microscopic deformation of surface roughness peaks. At the end of the hot stamping process, the HTC reached a pressure-dependent steady-state value between 4320 and 7860 W/m2·K when the blank and die temperatures equalize.

Influence of Surface Roughness on Contact Heat Transfer

2010 ◽  
Author(s):  
V. A. Ustinov ◽  
R. Kneer ◽  
F. Al-Sibai ◽  
S. G. Schulz ◽  
E. El-Magd
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Contact Area ◽  
Real Contact Area ◽  
Contact Heat ◽  
Real Contact ◽  
Contact Heat Transfer ◽  
Contact Pressures

Almost all technical devices in use today are assemblies of individual pieces. For all force-based assembly methods, such as bolting or press-fitting, the thermal behavior is influenced by the contact resistance at the joint surface. For metal pieces in contact with each other, the authors have developed a measurement method and analysis tools enabling the determination of the contact heat transfer coefficient. Previously published results [1, 2, 3] have shown the dependence of the contact heat transfer coefficient on surface structure, contact pressure and material properties. The present work provides experimental and analytical data for the contact heat transfer coefficient and also proposes a model for calculating the real contact area of two surfaces which are placed under different contact pressures. Experiments were conducted for two material combinations with three different surface structures, while varying the contact pressures from 7 MPa to 230 MPa. When selecting average surface roughness (Rz) as a characterizing parameter for surface structure, the results did not show a consistent trend. Thus, in this paper Rz was replaced by the real contact area between the two surfaces of interest. This area was determined by applying a refined method based on surface roughness measurements. The experimental data show a better consistency, when plotting the contact heat transfer coefficient relative to real contact area (Fk) rather than the previously used Rz–values.

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