Benedict Stampfer, M.Sc.
Forschungs- und Arbeitsgebiete:
- Surface Engineering bei der Zerspanung von 42CrMo4 QT
- Modellbildung, Multisensorik und Prozessregelung
- Kühlschmierstrategien in der Zerspanung
- Kryogene Zerspanung mit flüssigem Stickstoff
- Zerspanung von Ti-6Al-4V
- Zerspanungssimulation mittels der Finite-Elemente-Methode (FEM)
- Organisationstätigkeit im DFG SPP 2086
- DFG: Vermeidung thermisch bedingter Verzüge bei der Zerspanung von Ti-6Al-4V durch lokale kryogene Zerspanung
- DFG SPP 2086: Prozessintegrierte Softsensorik zur Oberflächenkonditionierung beim Außenlängsdrehen von 42CrMo4
|[ 1 ]|| Stampfer, B.; Zanger, F. & Schulze, V. (2018), In-Process Analysis of Minimum Quantity Lubrication during Drilling of AISI 4140. Advances in Production Research, Hrsg. Schmitt, R. & Schuh, G., S. 541-550.
Minimum quantity lubrication (MQL) is an established concept to meet high ecological and economical demands in metal machining. Compared to flood cooling, MQL massively reduces the efforts associated with the supply and disposal of the lubricants and the handling of emulsion contaminated chips. At the same time, MQL can reach a similar tool life. The mechanisms that have an influence on this effect are a matter of ongoing research. For this work, aerosol was generated by a 1-channel MQL system and supplied to a drilling process with AISI 4140 specimen. The drilling torque, feed force and workpiece temperatures are evaluated under different MQL air input pressures and tool cooling channel lengths. The results are interpreted by the help of flood cooling reference tests and high speed camera recordings, which reveal the open-jet atomisation of lubrication ligaments at the tool exit, arising from different MQL operation parameters.
|[ 2 ]|| Stampfer, B.; Golda, P.; Zanger, F.; Schießl, R.; Maas, U. & Schulze, V. (2019), Thermomechanically coupled numerical simulation of cryogenic orthogonal cutting. 17th CIRP Conference on Modelling of Machining Operations (17th CIRP CMMO), Hrsg. Ozturk, E.; Mcleay, T. & Msaoubi, R., S. 438-443.
During machining of Ti-6Al-4V, high thermal loads arise, which demand for advanced cooling concepts, such as the application of liquid nitrogen. An efficient approach to analyze the thermomechanical mechanisms which influence the tool life and the workpiece distortions is the usage of coupled numerical simulations. In this work, the Finite -Element-Method was used to simulate the tool-workpiece-interaction and the chip formation, whereas the detailed treatment of the nitrogen fluid flow and its heat transfer is solved by an in-house program using the Finite-Difference-Method. Both simulations are coupled by appropriate boundary conditions, which are updated iteratively during the calculation.
|[ 3 ]|| Stampfer, B.; Böttger, D.; Gauder, D.; Zanger, F.; Häfner, B.; Straß, B.; Wolter, B.; Lanza, G. & Schulze, V. (2020), Experimental identification of a surface integrity model for turning of AISI4140. Procedia CIRP 87, S. 83-88.
In this work an experimental study of the turning of AISI4140 is presented. The scope is the understanding of the workpiece microstructure and hardness-depth-profiles which result from different cutting conditions and thus thermomechanical surface loads. The regarded input parameters are the cutting velocity (vc = 100, 300 m/min), feed rate (f = 0.1, 0.3 mm), cutting depth (ap = 0.3, 1.2 mm) and the heat treatment of the workpiece (tempering temperatures 300, 450 and 600?C). The experimental data is interpreted in terms of machining mechanisms and material phenomena, e.g. the generation of white layers, which influence the surface hardness. Hereby the process forces are analyzed as well. The gained knowledge is the prerequisite of a workpiece focused process control.
|[ 4 ]|| Stampfer, B.; Golda, P.; Schießl, R.; Maas, U. & Schulze, V. (2020), Cryogenic orthogonal turning of Ti-6Al-4V, The International Journal of Advanced Manufacturing Technology, Band 111, S. 359-369. 10.1007/s00170-020-06105-z [30.11.-1].
Cooling of machining operations by liquid nitrogen is a promising approach for reducing cutting temperatures, increasing tool life and improving the workpiece surface integrity. Unfortunately, the cooling fluid tends to evaporate within the supply channel. This induces process variations and hinders the use of nitrogen cooling in commercial applications. In this work, the coolant is applied via the tool?s rake face during orthogonal turning of Ti-6Al-4V. The effect of a nitrogen supply pressure adjustment and a subcooler usage ? proposed here for the first time for machining ? is analyzed in terms of process forces, tool temperatures and wear patterns, taken dry cutting as a reference. Thereby, reliable cooling strategies are identified for cryogenic cutting.
|[ 5 ]|| Golda, P.; Schießl, R.; Stampfer, B.; Schulze, V. & Maas, U. (2020), Experimental determination of the cooling performance of liquid nitrogen for machining conditions, International Journal of Heat and Mass Transfer, Band 164, S. 120588 (1-11). 10.1016/j.ijheatmasstransfer.2020.120588 [30.11.-1].
This paper presents an experimental investigation of cryogenic cooling with liquid nitrogen. A thermal imaging camera is used to measure the temperature distribution of a pre-heated titanium alloy (Ti-6Al- 4V) specimen interacting with a flow of liquid nitrogen. The main objective of this work is to determine the surface heat transfer in a robust way. A new method, the so-called inverse global integration method (IGIM), is introduced which allows the calculation of the heat transfer from a solid body to the cryo- genic medium using all available pixel points of a thermogram. Reproducible and accurate results could be achieved by ensuring well-defined initial and boundary conditions during the execution of the exper- iment. The parameters with the highest impact on the heat transfer are the surface temperature, nozzle distance, as well as the working pressure in the nitrogen tank. The work is completed by performing curve fitting on the experimental results in order to compare the cooling performance and to simplify the technical application.