Development of a quick test method for the characterisation of the in-process properties of conventional grinding tools
Final Report Abstract
Recent conventional grinding wheels present capable solutions for efficient high-tech manufacturing tasks. The performance of this tool category depends substantially on the grinding wheel specification, the used raw materials and the conditions at the wheel manufacturing process. Until now, the selection of conventional grinding wheels for specific manufacturing processes is mostly based on long lasting experiences and implicit knowledge. In this project investigations were carried out with the objective of developing a technological testing method, which allows an explicit systematic appraisal of the grinding performance of test wheels related to a reference wheel with well-known operational behaviour. At first established physical and technological testing methods were analyzed. It was found, that physical testing does not allow for detecting the influences of the used abrasive grain material. In technological testing with threshold methods concerning material removal and material removal rate a small selectivity appeared and inappropriate work piece qualities occurred. Therefore a test strategy was elaborated which allows a differentiate analysis of the grinding wheel properties under grinding conditions similar to reality. For this purpose a simple profile element in hardened steel rings is machined by a cylindrical plunge grinding process. Compared with the state of the art, the developed testing method combines roughing and finishing steps without intermediate dressing. In doing so, the profile properties as well as the smoothing properties of a test wheel can be reliable evaluated by comparing the achieved work result with the derived characteristic values of the reference wheel. In technological investigations various grinding wheels were tested and appraised concerning the achieved work result. Thereby different sintered corundum abrasive grains types in different percentages as well as different fused corundum grain types were used and different volumetric specifications were analyzed. Furthermore force measurements were carried out to deepen the understanding of the acting principles at grinding with different sintered corundum abrasive grain types. It was ascertained that the grinding forces depend mainly on the type of sintered corundum grain. In addition, the influences of the sintered corundum percentage and the Norton hardness on the grinding behaviour were analyzed. In continuation of the achieved results further technological investigations at different process parameters were carried out. It was found, that under the defined test conditions a technological working point for any test wheel can be reliably identified by a three stage variation of the specific material removal rate Q’w. Based on machine and tool cost a practical oriented wheel appraisal can be conducted. Finally a simulation tool for predicting the grinding wheel radial wear at different process parameters depending on the sintered corundum percentage was developed. At higher material removal rates the simulated values show a high compliance with the experimental data. Thus the working principles at grinding with SK-wheels can now be explained based on deepened knowledge.
Publications
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Grain mill test for sintered microcrystalline aluminum oxide abrasive grains. Production Engineering - Research and development, 5 (2011), pp. 523 - 529
Uhlmann, E.; Hasper G.
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Influence of different microcrystalline Al 2O3 on thermal damage and profile accuracy of the workpiece in cylindrical plunge grinding. In: Proceedings 21st International Congress of Mechanical Engineering, Natal (Br) 24.-28. October 2011
Weingaertner, W. L.; Uhlmann, E.; Hasper, G.; Benini, L.
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Vergleichende Bewertung der Bruchmechanik mikrokristalliner Sinterkorundkörnungen anhand von Mahlkraftanalysen und Untersuchungen zum Außenrundeinstechprofilschleifen. In: 65. Jahrbuch Schleifen, Honen, Läppen und Polieren, Verfahren und Maschinen. Hoffmeister, H. W.; Denkena, B. Essen: Vulkan, (2011), pp. 61 - 73
Uhlmann, E.; Hasper, G.
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Wear prediction at grinding with sintered corundum grinding wheels, Technical Contribution 62nd CIRP General Assembly, Hong Kong, 19.-25.08.2012
Uhlmann, E.; Hasper, G..; Heitmüller, F.
