Adjustable stiffness compensation for monolithic high-precision mechanisms. - In: Proceedings of the 22nd International Conference of the European Society for Precision Engineering and Nanotechnology, (2022), S. 67-68
An enhanced mechanism for a Kibble balance at the National Institute of Standards and Technology. - In: Proceedings of the 22nd International Conference of the European Society for Precision Engineering and Nanotechnology, (2022), S. 55-58
Aerostatically sealed chamber as a robust aerostatic bearing. - In: Tribology international, ISSN 1879-2464, Bd. 173 (2022), 107614, S. 1-10
Aerostatic bearings are typically used in ultra precision and high speed applications in controlled environments. The present study expands this operating domain. The present study experimentally investigates the performance and feasibility of a novel design for a robust air bearing consisting of an aerostatically sealed pressurized volume. A suitable operating domain for the bearing system was characterized based on measurements of the load capacity, friction moment, chamber flow, and seal flow rate at various opposing surface run-outs and supply pressures. The highest measured load capacity was 18.86 kN at 0.330 mm run-out, and decreased to 12.22 kN load at 3.804 mm run-out. The study provided corroborative evidence on the feasibility of the proposed chamber based bearing design.
https://doi.org/10.1016/j.triboint.2022.107614
Adjustment concept for compensating for stiffness and tilt sensitivity of a novel monolithic electromagnetic force compensation (EMFC) weighing cell. - In: Journal of sensors and sensor systems, ISSN 2194-878X, Bd. 11 (2022), 1, S. 109-116
This paper describes the new adjustment concept of novel planar, monolithic, high-precision electromagnetic force compensation weighing cells. The concept allows the stiffness and the tilt sensitivity of the compliant mechanisms that are dependent on the nominal load on the weighing pan to be adjusted to an optimum. The new mechanism is set up and adjusted according to the developed mechanical model. For evaluation of the concept the system is tested on a high-precision tilt table and under high vacuum conditions in the environment of a commercially available mass comparator.
https://doi.org/10.5194/jsss-11-109-2022
On the influence of geometrical deviations of flexure hinges on the trajectory behaviour of straight-line compliant mechanisms for ultra-precision applications :
Zum Einfluss von geometrischen Abweichungen von Festkörpergelenken auf das Bahnverhalten von nachgiebigen Geradführungsmechanismen für Ultrapräzisionsanwendungen. - In: Achte IFToMM D-A-CH Konferenz 2022, (2022), insges. 2 S.
https://doi.org/10.17185/duepublico/75447
Investigations on low-friction kinematic couplings based on compliant mechanism. - In: Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, (2021), S. 517-518
Traceable 5D-nanofabrication with nano positioning and nano measuring machines. - In: Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, (2021), S. 333-336
Today, besides the ongoing progress in the reduction of feature sizes, the measuring and fabrication of freeform surfaces with nanometre uncertainty, e.g. for aspheric lenses or structures with high aspect ratios, are a challenging task. Usually, dealing with such objects is limited by the local tilt angle between the object surface and the tool axis. There are different approaches to perform such measurements. In this paper, an extension of the Nano Measuring Machine NMM-1 with two rotational axes is described. With the proposed setup, it is possible to orientate the tool-axis perpendicular to the sample in every position, allowing larger angles to be measured / structured and minimising the uncertainty of the process e.g. due to the tilt dependency of the tool. Various machine designs are investigated and finally a solution with one rotary and one goniometer stage is integrated, preserving the existing machine infrastructure and allowing the addressability of a full hemisphere without limiting the measuring volume. As the tool centre point maintains its position during tool rotation, the Abbe principle is still fulfilled in every angular orientation. Emphasis was put on the metrological traceability of the whole system, including linear and rotary axes as well the tool itself. This was achieved by using a reference hemisphere, compensating the trajectory errors of the rotational axes. For the developed arrangement, the measurement uncertainty was investigated and several strategies for an in-situ-calibration of the additional axes are described. Finally, nanofabrication on large slopes is demonstrated.
On the development of five-axes nanopositioning machines for measurement and fabrication purposes based on Cartesian systems. - In: Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, (2021), S. 213-216
Behaviour of porous aerostatic bearings with various restrictor permeabilities. - In: Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, (2021), S. 115-118
Aerostatic bearings are externally pressurized gas lubricated bearings. Aerostatic bearings are used in high speed and precision motion applications due to low friction and high accuracy. They use a restrictor to limit the flow of the gas into the bearing gap. The presence of the restrictor increases the stability of the bearing against self-excited vibrations. This study focuses on porous graphite restrictors and the effect of permeability on the behaviour of the bearing. The bearings were studied both experimentally and with a simulation model. Flat bearing pads with 37 mm diameter and different restrictor bulk permeability were manufactured and tested. Experimental measurements were conducted on a test setup allowing loading of the bearing against a ground steel plate. The load was supplied with a series of weights. The air gap was measured with a linear length gauge, measuring the displacement of the air bearing. The pressure was controlled with a regulator and the flow rate into the bearing was measured. In order to build an accurate simulation model, the permeability of the used material was calculated from the measured short circuit flow through each 4.5 mm thick sample. The flow in the porous material and in the restrictive layer follows Darcy's law, the flow in the air gap is described by the Navier-Stokes-equation. The simulation model was validated with experimental results. Measurement and simulation results include the air gap height, load and flow rate at a supply pressure of 0.4 MPa. According to previous research and preliminary results the surface restrictor layer has increased the resistance of the bearing to self-excited airhammer vibration, leading to a higher load capacity.
Torque-compensating adjustment drive for mechanically sensitive devices. - In: Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, (2021), S. 113-114