The principle of gear hobbing process is to mesh the gear workpiece with the hob. The gear hobbing hob is grooved in the direction perpendicular to the spiral groove to form several cutting edges, and its normal section has the shape of rack. Therefore, when the gear hob rotates continuously, the cutter teeth can be regarded as the movement of an infinite rack. At the same time, the cutter teeth are cut from top to bottom to maintain the meshing relationship between the rack (gear hobbing HOB) and the gear blank, and the gear hobbing hob can process the involute tooth shape on the gear blank. The ideal gear hobbing processing is that the gear hobbing hob makes pure rolling meshing with the gear, continuously cuts the gear, and finally processes the ideal gear; In the actual machining process, the gear hobbing cutter does not cut the gear workpiece continuously, but cuts intermittently, which leads to the sawtooth profile error caused by intermittent cutting in the gear hobbing process.
The machining principle error of gear hobbing machining and the influence of the factors affecting the error on the error are analyzed.
The mapping relationship between gear hobbing principle error and gear machining accuracy is studied. In the process of gear hobbing, the gear machining error caused by the gear hobbing principle is analyzed; The gear hobbing principle error is modeled, the mapping relationship between gear principle error and gear machining error is obtained, the relevant factors affecting gear machining error are found out, and the influence of various factors on gear hobbing machining accuracy is discussed. Increasing the number of gear teeth and increasing the number of cutting edges of gear hobbing hob can increase gear machining accuracy and reduce tooth profile error.
The influence of the number of gear teeth on the tooth profile error is shown as an inverse function image. To a certain extent, increasing the number of gear teeth will reduce the tooth profile error and increase the gear accuracy. However, when the number of teeth is about 45, increasing the number of teeth is not so obvious for the tooth profile error; From the influence curve of cutting edge on gear machining accuracy, it can be seen that increasing the number of cutting edges of gear can effectively and significantly improve gear hobbing accuracy within a certain range, but when the number of cutting edges increases to 20, the influence on tooth profile error is not so obvious.