3D model for gears
Holistic characterization of helical machine elements
Gears and screw threads of the most varied types are important components in all areas of mechanical engineering. Tight manufacturing tolerances define the requirements placed on the measuring equipment used for quality assurance purposes along the entire scale of quantities and across diverse sectors. To ensure that the evaluation of a component’s quality is reliable and relevant to its function, the measurement processes used must be not only fast and accurate, but also, and most importantly, holistic. This means for one thing that the geometry must be acquired along all function surfaces and, for another, that all characteristics be evaluated in a single geometry element based on only one reference coordinate system.
Modern coordinate measurement systems provide areal information fast and reliably with regard to the dimension, form and position errors of helical machine elements. Up to now, however, standard evaluation procedures required reducing this data to individual lines. A major share of the data points thus had to be discarded. The new procedure enables the evaluation of areal measurement data distributed anywhere along the entire external surface. This procedure is based on a universal 3D model that allows helical machine elements to be described by means of a unique set of geometry parameters. The model is best-fitted into the data point cloud using a foot-point iteration algorithm. The actual values of the geometry parameters yielded in this way can then be converted into the determinants already established in conventional procedures.
It is planned to enhance this new procedure to characterize additional types of machine elements (such as those of bevel gears). Moreover, we are working to incorporate the procedure into standards in order to promote its use in industry.
Contact
Martin Stein
Department 5.3
Coordinate Metrology
Phone: +49 531 592-5335
martin.stein(at)ptb.de
Scientific publication
M. Stein, F. Keller, A. Przyklenk: A unified theory for 3D gear and thread metrology. Appl. Sci. 11, 7611 (2021)