scholarly journals A Study of Interface Heat Transfer Coefficient Between Die and Workpiece for Hot Forging

2005 ◽  
Vol 14 (5) ◽  
pp. 460-465 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Forging ◽  
Interface Heat Transfer Coefficient ◽  
Interface Heat Transfer ◽  
Interface Heat

Determination of the Interface Heat Transfer Coefficient for Non-Isothermal Bulk-Forming Processes

1987 ◽  
Vol 109 (1) ◽  
pp. 49-57 ◽  
Author(s):  
S. L. Semiatin ◽  
E. W. Collings ◽  
V. E. Wood ◽  
T. Altan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Transfer Coefficients ◽  
Interface Heat Transfer Coefficient ◽  
Bulk Forming ◽  
Interface Heat Transfer ◽  
Aluminum Alloy 2024 ◽  
Interface Heat

Experimental and analytical techniques have been developed for the determination of the interface heat transfer coefficient for nonisothermal bulk-forming processes. A fixture consisting of two flat IN-100 alloy dies was instrumented with high-response thermocouples. With this tooling, heat-transfer experiments were conducted in which (1) the two dies were heated to different temperatures and brought together under varying pressure levels and (2) the two dies were heated to the same temperature and were used to upset an aluminum alloy 2024-0 ring specimen heated to a higher temperature. Data from both sets of tests were analyzed to determine heat-transfer coefficients by using calibration curves derived from analytical and finite-difference method solutions. By this means, the effects of interface pressure, deformation, and deformation rate on the heat-transfer coefficient were established.

The Effect of Air Gap between Casting and Water-Cooled Mold on Interface Heat Transfer Coefficient

2017 ◽  
Vol 893 ◽  
pp. 174-180 ◽  
Author(s):  
Yi Dan Zeng ◽  
Qing Hu Yao ◽  
Xia Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Solidification Process ◽  
Casting Process ◽  
Air Gap ◽  
Gap Formation ◽  
Interface Heat Transfer Coefficient ◽  
Interface Heat Transfer ◽  
Interface Heat

Water-cooled casting is a new casting process. It allows even large castings to solidify rapidly, thereby reducing segregation and grain refinement. It has drawn the attention of both domestic and foreign businesses. Heat transfer at the casting/water-cooled mold interface controls the cooling rate of the casting. During the solidification process, because of the contraction that takes place during casting, an air gap can form between the casting and the water-cooled mold. This air gap hinders heat transfer between the casting and the mold, leading to a rapid drop in the interface heat transfer coefficient (IHTC). The purpose of the present study was to assess the effects of the width of the air gap and the duration of gap formation on IHTC. During the experiment, the casting temperature curve was determined in the presence of the interface air gap, and then inverse calculation was performed using PROCAST software to determine the IHTC of casting/water-cooled mold. Results showed that, after the formation of the air gap, IHTC first exhibited a rapid decrease, followed by an increase and then another decrease; IHTC was found to decrease as gap width increased and as the duration of gap formation increased.

Numerical Simulation and Process Optimization of Investment Casting of the Blades for High Nb Containing TiAl Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 105-110 ◽  
Author(s):  
Liang Yang ◽  
Li Hua Chai ◽  
Lai Qi Zhang ◽  
Jun Pin Lin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Investment Casting ◽  
Casting Temperature ◽  
Interface Heat Transfer Coefficient ◽  
Preheating Temperature ◽  
Interface Heat Transfer ◽  
Porosity Defects ◽  
Interface Heat

Low pressure turbine blades (LPT) made by investment casting from intermetallic titanium aluminide alloys for aero-engine applications have about 50% weight saving compared with that from nickel-based counterparts. Investment casting process of the low pressure turbine blades for high Nb containing TiAl alloy was simulated by Procast. The height of the blade is about 125mm and the thinnest part of it is about 6mm. Compositions of the cast and mould are Ti-45.5Al-8Nb (at %) and Zircon sand, respectively. The simulation result showed that there were porosities appearing in the centre of blades, which may be due to the formation of isolated liquid. In this work, the simulation, analysis and comparison of different casting ways were carried out. The result showed that compared with top and bottom casting, blades made by side casting have less porosity defects. And then the casting temperature, casting velocity, mould preheating temperature and interface heat transfer coefficient were optimized based on orthogonal design. The result also indicated that the influence of process parameters to porosity defects of blades can be ranked from strong to weak as follow: casting temperature>shell mould preheating temperature>casting velocity>interface heat transfer coefficient. When the casting temperature was 1700, the mould preheating temperature was 500, the casting velocity was 0.5 m·s-1, and the interface heat transfer coefficient was 500 W·m-2·K-1, the volume of porosity defects was the smallest.

An investigative study of the interface heat transfer coefficient for finite element modelling of high-speed machining

2008 ◽  
Vol 222 (11) ◽  
pp. 1405-1416 ◽  
Author(s):  
S A Iqbal ◽  
P T Mativenga ◽  
M A Sheikh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Metal Forming ◽  
Machining Process ◽  
Interface Heat Transfer Coefficient ◽  
Metal Machining ◽  
Interface Heat Transfer ◽  
Set Up ◽  
Interface Heat

This paper is concerned with the development of an experimental set-up and finite element (FE) modelling of dry sliding of metals to estimate the interface heat transfer coefficient. Heat transfer between the chip, the tool, and the environment during the metal-machining process has an impact on the temperatures and on the wear mechanisms, and hence on the tool life and on the accuracy of the machined component. For modelling of the metal-machining process, the interface heat transfer coefficient is an important input parameter to quantify the transfer of heat between the chip and the tool and to predict the temperature distribution accurately within the cutting tool. In previous studies involving FE analysis of the metal-machining process, the heat transfer coefficient has been assumed to be between 10 kW/m2 °C and 100 000 kW/m2 °C, with a background from metal-forming processes (especially forging). Based on the operating characteristics, metal-forming and metal-machining processes are different in nature. Hence there was a need to develop a procedure close to the metal-machining process, to estimate this parameter in order to increase the reliability of FE models. To this end, an experimental set-up was developed in which an uncoated cemented carbide pin was rubbed against a steel workpiece while the later was rotated at speeds similar to the cutting tests. This modified pin-on-disc set-up was equipped with temperature and force-monitoring equipment. An FE model was constructed for heat generation and frictional contact. The experimental and modelling results of the dry sliding process yield the interface heat transfer coefficient for a range of rubbing speeds.

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