30 lines
2.8 KiB
TeX
30 lines
2.8 KiB
TeX
% !TeX root = ../dissertation.tex
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\chapter{Process Charcterization}
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\label{cha:process_charcterization}
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Induction heating, despite all its positive aspects, is a difficult process to control due to it's multi-physical nature.
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Annika Eggbauer described in her PhD\cite{eggbauer2018inductive} the influence of heating speed on the resulting quenched microstructure, on top of austenitization temperature, hold time, and quenching parameters.
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This influence of the full heating curve compounds with the fact that every the heat generation of an induction setup are unique to each pairing of material and inductor geometry.
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As such, heavy instrumentation would be required to collect adequate physical data as input for a full process simulation:
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Precise voltage or current measurements for the electro-magnetic simulation of heat generation, as well as detailed termaertaure measurements at several key points of the volume to easily verify the simulation.
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Many industrial induction ovens are however not instrumented beyond a power meter, and even that will not record information about the transformer's efficiency and output waveform.
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For this reason, the \emph{Material Center Leoben} (MCL) commissioned an induction heating teat rig equipped with a bank of thermocouple endpoints.
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This machine has a maximum power of <??>, supplied by a <??> transformer, and can be run in constant-voltage, constant-current, and constant-power mode.
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A series of induction experiments was conducted by our research group to obtain data on a induction hardening procedure, whose temperature curve closely imitated that of the industrial prcess we aimed to simulate in part~\ref{part:crankshaft}.
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The material chosen for these experiments was 50CrMo4 steel whose chemical composition is close to that of the proprietary C38p Steel used in the crankshafts of part~\ref{part:crankshaft}.
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The experiments on rod samples done on the MCL in-house induction test rig were well instrumented and published under J\'aszfi \emph{et al.}\cite{jaszfi2019influence, jaszfi2022indirect, jaszfi2022residual}
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The induction test rig was configured to approximate a linear temperature increase up to the assumed maximum of \qty{1050}{\degreeCelsius}?? which was held for \qty{10}{\s}, after which quenching fluid was injected in between the induction coil to achieve a cooling coefficient of $\lambda = 0.1$ or \qtyrange{500}{300}{\degreeCelsius} in \qty{10}{\s}??.
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The rod samples had holes drilled for thermocouples at center height of the coil at \qtylist{0.5;10.5}{\mm} depth.
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A procedure for characterizing the electrical signal that drives the induction coil is given in appendix~\ref{apx:pub1}.
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That article defines a cutoff up to which harmonic solutions to the electromagnitc simulation (see section~\ref{sec:the_finite_element_method}) are viable.
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