Böhmermann, Florian
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Böhmermann, Florian
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Böhmermann, Florian
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Item type:Publication, Development and application of a test rig for tribological investigations under impact loadsThe investigation and the understanding of frictional mechanisms occurring between forming dies and work pieces in tribological contact is the prerequisite for the development of novel, dry bulk metal forming processes such as dry rotary swaging. The capability to conduct tribological investigations within the actual forming processes, however, is strongly limited, e.g. due to the limited accessibility of force measurement equipment. This work presents the development and application of a tribological test rig mimicking typical contact geometries and high impact loads associated with infeed rotary swaging for process-independent tribological investigations. The development comprises the designing process based on rotary swaging process simulations, setup assembly, and calibration procedure. Subsequently, the functionality of the test rig was demonstrated successfully, determining the distinct frictional properties under lubricated and dry conditions of various samples with structured surfaces representative for rotary swaging dies.journal articleBand:19118 93 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Abrasive Particle Generation in Dry Rotary Swaging(2017); ; 463 105 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tribological Performance of Textured Micro Forming Dies(2016); ; Riemer, OltmannAim of this work is the tribological investigation of micro structured surfaces generated by micro milling and the performance testing of a micro structured micro deep drawing die. Three samples exhibiting different micro structured surfaces with arithmetical mean heights Sa in a range of 148 nm to 741 nm were manufactured by micro milling. The surface texture is determined by the process parameters of the micro milling operation. Tribological properties of the micro structured surfaces were investigated by means of a ball-on-plate micro tribometer and compared to those of a polished reference sample (Sa = 24 nm), a clear dependence of the frictional properties on the surface roughness was found. Lowest friction μ =0.26 was achieved for the sample with a roughness Sa = 148 nm. Surfaces with higher or lower roughness provoked increased friction in tribological testing being associated with an interlocking of surfaceâ s asperities or dominant adhesion, respectively. Subsequently, micro structures were machined into the surface of a micro deep drawing die for drawing of rectangular micro cups. The performance of this die was tested in deep drawing experiments against a polished reference die by means of achievable drawing ratio. At this stage the full advantage of the micro structuring of die surfaces was not achieved, yet. Still particular challenges within the micro regime, e.g. alignment of punch and die as well as blank positioning, have to be improved.journal articleBand:Volume 2600 159 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Potentials of Dry Rotary SwagingInfeed rotary swaging is an appropriate cold massive forging technology for the manufacture of cylindrical shaped components made of iron or aluminum base alloys. The process is focused on reducing the cross-section of full profiles or tubes and is e.g. widely used in automotive industry. The design of swaged hollow components can easily be adapted to the external load in such a way, that the wall thickness is partially reduced and the material cross-section is increased where needed. The above-mentioned advantages result in a high potential for light-weight production while the produced components exhibit high geometric accuracy and surface quality. However, an excellent CO2 balance is yet limited due to high demands for lubricants significantly increasing the number of process steps for further component refinement. In order to increase the overall process efficiency, a changeover to a dry process design becomes necessary. A dry processing will cause high die wear and deterioration of workpiece quality. The most important functions of the lubricant have to be substituted by other approaches and strategies. Development and removal of heat, generation and discharge of wear debris and, above all, die wear and the resulting workpiece quality have to be considered. The effective tribological friction conditions have to be adjusted by means of geometric adaptations of the active die surfaces to realize good workpiece qualities at comparable cycle times. This paper gives a review of the state-of-the-art in dry rotary swaging. Extensive experiments in laboratory scale as well as application tests were performed with various die setups. The most important findings regarding wear, wear minimization, process kinematics, workpiece quality, FEM simulation are presented. The overarching goal is to achieve a longterm stability for the successful dry processing.journal article738 596