On-machine quasi-3D scanning measurement of bevel gears on a five-axis CNC machine

Abstract

Most commercialized measuring machines for bevel gears have a four-axis structure plus a 3D scanning probe. Because these probes are highly efficient, a large number of high-precision gear grinding and complex machines now apply them to detect tooth surface contour error. Nevertheless, such probes are still too expensive to implement on a milling machine. This paper, therefore, proposes a quasi-3D probe as a better solution for cost reduction. More specifically, the study develops an on-machine measurement system on five-axis machines which are needed for producing bevel gears. It employs a quasi-3D scanning probe whose sensor can detect in xyz directions while outputting only a one-dimensional (1D) deviation. This novel method enables measurement using solely a four-axis movement, meaning that only four coordinates are needed to measure pitch and topography. These coordinates are derived by first establishing mathematical models of bevel gear measurement. Also developed is an evaluation program that communicates between the PC and CNC controller. The proposed mathematical models are then applied to a five-axis CNC (computer numerical control) machine equipped with a Siemens 840Dsl controller and verified by comparing the results of this measurement and evaluation with the accuracy report for the same gear measured on a dedicated gear measurement machine.