Development of a novel instrument for measuring helix deviations of spur gear artefact to submicron accuracy

Dalian University of Technology, China (DLUT) successfully developed class-1 spur gear artefacts. However, the expanded uncertainty U-95 of the existing instrument for measuring gear helix deviations is more than 1/3 of the class-1 gear helix tolerances, which cannot meet the measuring requirements of the helix deviations for the class-1 spur gear artefacts. In order to solve these problems, the influences of the mandrel locating error on the gear helix deviations are analysed, and a novel instrument for measuring spur gear helix deviations to submicron accuracy is designed. The instrument is optimized for the measurement of specific gear types (external teeth, medium module, with through-hole, reference diameter <= 126 mm). The expanded uncertainties U-95 of the instrument for measuring the total helix deviation F-beta, the helix slope deviation f(H beta) and the helix form deviation f(f beta) are 0.23 mu m, 0.20 mu m and 0.18 mu m respectively. This is less than 1/3 of the class-1 gear helix tolerances (the total helix tolerance F-beta T, the helix slope tolerance f(H beta T) and the helix form tolerance f(f beta T) are 2.4 mu m, 1.6 mu m and 1.8 mu m respectively: ISO 1328-1:2013). Verification measurements with a calibrated measurement standard show the proficiency.