Um den Abschreckvorgang von Stahlwerkstücken in einem Ölbad sowohl zeitlich als auch räumlich aufgelöst erfassen zu können, wurde ein Ultraschall-Messsystem entworfen und aufgebaut. Es basiert auf der Amplitudenerfassung der vom Bauteil reflektierten Ultraschallechos und ermöglicht es, den Übergang zwischen verschiedenen Siedephasen zu detektieren. Der Vergleich mit Kameraaufnahmen zeigt nur geringe Abweichungen, sodass das Verfahren zur Beurteilung von Abschreckprozessen eingesetzt werden kann.
This paper presents an ultrasonic method to measure the movement of workpiece surfaces during quenching processes in liquids in order to estimate the time-dependent in-process distortion of the workpiece. The movement is determined by the time-of-flight of the ultrasonic signals from the transducer to the surface and back again (impuls-echo-method). As the simulation of quenching processes depends on several assumptions of the model parameters and almost no experimental intermediate geometry data for quenching processes exist, the in-process-measurements of the surface movement can be used to improve the simulation models and also to extend the knowledge about model parameters. The paper shows an analysis of the ultrasonic data for measurements on cylindrical discs of 20MnCr5 steel and compares the ultrasonic in-process results with simulated data. Additionally, coordinate measurements carried out before and after the heat treatment are presented as a reference and the uncertainty of the ultrasonic measurements is discussed.
Laser chemical machining (LCM) is intentionally limited in its removal rate to avoid disturbing boiling bubbles in the process fluid. To overcome this limitation, an enhanced material removal model is required based on surface geometry and temperature in-process data. For this purpose, fluorescence measurements and confocal microscopy are combined to enable in-process experiments in LCM environment. Derived from fluorescence effects, the geometry and surface temperature are indirectly determined under LCM-equivalent conditions such as thick fluid layers and gas bubbles in the beam path.
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