@article{TroeberHacklLeitneretal.2023, author = {Tr{\"o}ber, Philipp and Hackl, Alfred and Leitner, Harald and Welm, Markus and Demmel, Peter and Golle, Matthias and Volk, Wolfram}, title = {On the Sensitivity of a Tool-Workpiece Thermocouple to Chemical Composition and Microstructure}, volume = {94}, pages = {2200456}, journal = {Steel research international}, number = {4}, publisher = {Wiley}, address = {Weinheim}, issn = {1869-344X}, doi = {https://doi.org/10.1002/srin.202200456}, year = {2023}, abstract = {Meeting the increasing demands on part quality and profitability of manufacturing processes despite difficult-to-machine materials is only possible with a deep understanding of the process. Herein, knowledge about the process temperature is of critical importance since it affects the material properties, such as hardness or forming behavior, as well as the chemical and physical interactions between the tool, workpiece, and lubricant. A proven thermoelectric method of temperature measurement in machining, forming, and blanking is a tool-workpiece thermocouple. Herein, instantaneous measurement of the temperature development is allowed in this setup during the manufacturing process in situ at the contact area of the tool and workpiece. The accuracy of this method is dependent on the calibration of the thermocouple, for which the Seebeck coefficients of the tool and workpiece material have to be determined. Usually, material samples from different batches are used for this purpose, although the resulting measurement errors due to slight changes in material properties are hardly known. The effects of small changes in the chemical composition and the transformation of the crystal lattice due to hardening on the Seebeck coefficient are investigated for the first time to allow precise quantification of the measurement error resulting from the calibration process.}, language = {en} } @article{WelmKindsmuellerTroeberetal.2023, author = {Welm, Markus and Kindsm{\"u}ller, Alexander and Tr{\"o}ber, Philipp and Dr{\"o}se, Lukas and Volk, Wolfram}, title = {Stresses between die and slug in blanking and their significance for slug pulling}, volume = {17}, journal = {Production Engineering: Research and Development}, number = {6}, publisher = {Springer}, address = {Berlin}, issn = {1863-7353}, doi = {https://doi.org/10.1007/s11740-023-01202-w}, pages = {875 -- 882}, year = {2023}, abstract = {The primary goal when manufacturing components in a blanking process is a high output to achieve good cost efficiency. Therefore, availability needs to be as high as possible. However, several process disturbances like slug pulling increase downtime and thus counteract this aim. Slug pulling is influenced by different forces that trigger the slug being pulled and those that hamper this effect. The predominating hampering force is friction between the slug and the die. Consequently, the influencing factors for this force have to be understood to reliably prevent slug pulling. In this publication, the influence of the die channel geometry on the occurring frictional forces and the part quality when blanking the non-alloy quality steel 1.0338 are investigated. Therefore, experiments with a variation of die channel geometry and punch diameter combined with force measurement are performed. Furthermore, a numeric simulation model based on the experimental results is used to investigate various die channels. The results enhance the knowledge about correlations between process parameters, slug properties, like slug deflection, and frictional forces and help to reliably prevent slug pulling.}, language = {en} } @article{PaetzoldTroeberWelmetal.2022, author = {P{\"a}tzold, Isabella and Tr{\"o}ber, Philipp and Welm, Markus and Volk, Wolfram}, title = {Blanking of Stainless Steel}, volume = {2022}, pages = {012030}, journal = {IOP Conference Series: Materials Science and Engineering}, number = {1238}, publisher = {IOP}, address = {Bristol}, issn = {1757-899X}, doi = {https://doi.org/10.1088/1757-899x/1238/1/012030}, year = {2022}, abstract = {Slug pulling, adhesion formation and edge fracture are major challenges in the sheet metal processing industry. They lead to a strong reduction in part quality, process stability as well as profitability. In this study, investigations are carried out on stainless steel X5CrNi18-10 to address the previous mentioned challenges. While slug pulling and edge fracture strongly depend on the geometric characteristics of active elements as well as the selection of process parameters, adhesion formation is mainly determined by temperature and thermoelectric currents. In this publication, the influence of the die channel geometry on the slug pulling effect and the part quality is investigated. Furthermore, the temperature profile over the shear cutting process as well as the resulting thermoelectric currents are determined for the test material. The relationship between edge crack sensitivity, shear cutting parameters and strategies is examined. These investigations thus form the basis for an improved understanding of the shear cutting of stainless steel.}, language = {en} } @article{TroeberWelmWeissetal.2019, author = {Tr{\"o}ber, Philipp and Welm, Markus and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {The influence of process parameters and sheet material on the temperature development in the forming zone}, volume = {6}, pages = {9}, journal = {Manufacturing Review}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {2265-4224}, doi = {https://doi.org/10.1051/mfreview/2019005}, year = {2019}, abstract = {Cold metal forming is a fast and economical way of producing a wide range of precise components. Its profitability mainly depends on part quality, process stability, and service intervals of tools. As these factors are all determined by tool wear, detailed process knowledge is indispensable to maximize profitability by minimizing wear. One of the most crucial factors in this context is temperature. During every forming process, a temperature rise occurs between tool and workpiece due to frictional heating and a large part of plastic work dissipating into heat. This phenomenon affects the whole forming process but especially tool wear. Currently, there is little solid information about temperatures occurring during forming operations. Therefore, the temperature was measured based on varying process parameters, sheet materials, and thicknesses in several embossing and blanking examinations. The use of a tool-workpiece thermocouple enabled accurate and instantaneous measurement during the process. The results presented show the strong influence of process and material parameters on temperatures in the forming zone.}, language = {en} } @article{WelmTroeberWeissetal.2020, author = {Welm, Markus and Tr{\"o}ber, Philipp and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {Thermoelectrically Based Approaches to Reduce Adhesive Wear During Blanking}, volume = {72}, journal = {JOM}, number = {7}, publisher = {Springer}, address = {New York}, issn = {1543-1851}, doi = {https://doi.org/10.1007/s11837-020-04191-8}, pages = {2525 -- 2535}, year = {2020}, abstract = {Almost every metal mass product goes through a blanking process. Especially when processing aluminum, adhesive wear is the main determinant of cost efficiency. Many investigations on wear-influencing factors have been conducted so far, but one major determinant is almost unnoticed, thermoelectric phenomena. Due to the Seebeck effect, thermoelectricity arises in every blanking tool. Recently published investigations show that the combination of tool and workpiece materials has a strong influence on occurring thermoelectric currents and thus on adhesive wear development. This can be traced back to dependence of the current strength and direction on the material-specific Seebeck coefficient. This article addresses the same phenomenon for a new parameter spectrum. Blanking experiments with aluminum EN AW 5083 were performed, investigating both thermoelectric currents and the amount of adhesive wear. Furthermore, the impact of external currents influencing the naturally occurring thermoelectricity on wear is shown. Improved measurements with a laser confocal microscope reveal a close correlation between the thermoelectric current profiles and adhesive wear pattern on the lateral surface of the punch. Together with a variation of tool material among high-speed steel 1.3343, stainless steel 1.4301 and cemented carbide CF-H40S, a strong relation between the Seebeck coefficients, electrical currents and tool wear could be found. Therefore, the actual findings confirm, deepen and extend previous results concerning thermoelectricity and adhesive wear.}, language = {en} } @inproceedings{WelmTroeberWeissetal.2020, author = {Welm, Markus and Tr{\"o}ber, Philipp and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {A Thermoelectrically Based Approach to Reduce Adhesive Wear During Blanking}, booktitle = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-36298-0}, doi = {https://doi.org/10.1007/978-3-030-36296-6_183}, pages = {1993 -- 2007}, year = {2020}, language = {en} } @article{TroeberWelmWeissetal.2021, author = {Tr{\"o}ber, Philipp and Welm, Markus and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {Temperature, thermoelectric current and adhesion formation during deep drawing}, volume = {2021}, pages = {203839}, journal = {Wear}, number = {477}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0043-1648}, doi = {https://doi.org/10.1016/j.wear.2021.203839}, year = {2021}, language = {en} }