The Establishment of Positionning Errors Influence of the Parallel Hobbing Cutter on the Machining Accuracy of the Spur Wheels

In this paper the influence carried out by the descentration errors of the parallel hobbing cutter on the machining accuracy of the spur wheels is presented. These errors lead to an incorrect position and setting of the parallel hobbing cutter on chuck. It Is due mainly to the too large hole tolerances of the parallel hobbing cutter and of the cutter arbor producing lots of errors of the teeth shape of the spur wheels. Researches carried out by the authors allowed the establishment of the shape and the value of these errors which are transmitted to the carried-out spur wheel. The errors of the tooth shape with pointed tips of the spur wheel lead to the increase of wear and noise on gear wheels. Owing to the fact that the value of these errors depends mainly on the dimensions of the parallel hobbing cutter, the results of the researches led to the conclusions that the parallel hobbing cutter with small diameters is more recommended because the descentration errors produce smaller errors at the machining of the spur wheels. At the same time the parallel hobbing cutters having diameters much smaller than those recommended by standards have got better performances.