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The thermal conditions like the temperature distribution and the heat fluxes during metal cutting have a major influence on the machinability, the tool lifetime, the metallurgical structure and thus the functionality of the work piece. This in particular applies for manufacturing processes like milling, drilling and turning for high-value turbomachinery components like impellers, combustion engines and compressors of the aerospace and automotive industry as well as energy generation, which play a major role in modern societies. However, numerous analytical and experimental efforts have been conducted in order to understand the thermal conditions in metal cutting, yet many questions still prevail. Most models are based on a stationary point of view and do not include time dependent effects like in intensity and distribution varying heat sources, varying engagement conditions and progressive tool wear. In order to cover such transient physics an analytical approach based on Green’s functions for the solution of the partial differential equations of unsteady heat conduction in solids is used to model entire transient temperature fields. The validation of the model is carried out in orthogonal cutting experiments not only punctually but also for entire temperature fields. For these experiments an integrated measurement of prevailing cutting force and temperature fields in the tool and the chip by means of high-speed thermography were applied. The thermal images were analyzed with regard to thermodynamic energy balancing in order to derive the heat partition between tool, chips and workpiece. The thus calculated heat flow into the tool was subsequently used in order to analytically model the transient volumetric temperature fields in the tool. The described methodology enables the modeling of the transient thermal state in the cutting zone and particular in the tool, which is directly linked to phenomena like tool wear and workpiece surface modifications.
Stagnation Flow and Heat Transfer From a Finite Disk Situated Perpendicular to a Uniform Stream
(2020)
Boiling heat transfer on large diamond and SiC heaters: The influence of thermal wall properties
(2011)
Production technology is a highly interdisciplinary field of research. It comprises different production domains (cutting, welding, forming, assembly, etc.), industry-sectors, materials and scales. Moreover, production has strong interdependencies with other scientific disciplines such as product development, materials engineering, business economics, information and communication technology, social science and natural science. Integrative Production Technology aims to develop a deep technology spanning perception to offer products matching customer and societal demands at competitive prices and to quickly adapt to market and societal changes while assuring constant and predictable product properties. The Cluster of Excellence (CoE) “Integrative Production Technology for High-Wage Countries” has initiated this special issue to present some of the newest results in the field.
Numerical Model of the Railway Brake Disk for the Temperature and Axial Thermal Stress Analyses
(2022)
Optimal control problems with delays in state and control and mixed control-state constraints"
(2009)
Confined Boiling Heat Transfer, Two-Phase Flow Patterns, and Jet Impingement in a Hele-Shaw Cell
(2017)
Experimental results are presented of a test of the theory of local turbulent heat transfer measurements proposed by Mocikat and Herwig in 2007. A miniaturized multi-layer heat transfer sensor was developed and employed in this study. The new heat transfer sensor was designed to work in air and liquids, and this capability enabled the simultaneous investigation of different Prandtl numbers. Two basic configurations, namely the flow past a blunt plate and the flow past an inclined square cylinder, were investigated in test sections of wind and water tunnels. Convective heat transfer coefficients were obtained through conventional testing (i.e., employing thoroughly heated test objects) and using the new miniaturized sensor approach (i.e., utilizing cold test objects without heating). The main prediction of the Mocikat-Herwig theory that a specific thermal adjustment coefficient of the employed actual miniaturized heat transfer sensor should exist in the fully turbulent flow regime was proven for developed two-dimensional flow. The observed effect of the Prandtl number on this coefficient was in good agreement with the prediction of the asymptotic expansion method. The square cylinder results indicated the inherent limits of the local turbulent heat transfer measurement approach, as suggested by Mocikat and Herwig.
Influence of Thermophysical Wall Properties During Pool Boiling on Large Diamond and SiC Heaters
(2014)
Numerical Calibration of Three-Dimensional Printed Five-Hole Probes for the Transonic Flow Regime
(2021)