Rapid and Precise Manufacturing of Special Involute Gears for Prototype Testing
Due to the steadily increasing demands on the power density of mechanical transmissions, gears with special geometries are increasingly coming into focus and therefore the need for short-term availability of prototypes. Such special gear designs are e.g. asymmetrical gears with different normal pressure angles on the drive and coast flank. These are particularly suitable for use in gearboxes with preferred driving direction, whereby the loaded flank can be optimized with regard to load carrying capacity. While for symmetrical gears with normal pressure angles in the range of an = 20° standardized calculation methods for gear design have been available for decades, mainly theoretical numerical investigations have been carried out on asymmetrical gears so far. For the qualification of any such designed asymmetrical gear geometry with increased load carrying capacity potential for use in industrial practice, however, reliable load carrying capacity values are required. Therefore, according to the current state of the art, prototype tests are indispensable to determine the actual gear strength. At the Gear Research Centre (FZG), such load capacity investigations are carried out using back-to-back test rigs and pulsator test rigs. The design and procurement of special tools for the production of such prototype gears is often time-consuming and expensive. In this paper, an alternative method for a fast and cost-efficient production of asymmetric gears for prototype tests is presented. The focus is on the grinding process from a full blank test specimen. This process was applied at the FZG in cooperation with Liebherr-Verzahntechnik GmbH in order to produce asymmetrical test gears for experimental investigations of the tooth root bending strength. Very good results were achieved with regard to gear quality and shape accuracy, especially in the tooth root area, which is then investigated. The results of this paper show therefore a suitable method for the fast, precise and cost-efficient production of special gears for prototype tests.
Authors: Christian Weber, M.Sc., Dr.-Ing. Thomas Tobie, and Prof. Dr.-Ing. Karsten Stahl,
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