Gear hobbing is processed by the principle of generating method. It can be used to process spur gear, helical gear, worm gear, spline or other special gears. In addition, the module range of gear hobbing processing is large. Gears with module less than 0.1 used in the instrument and gears with module greater than 40 can be processed by gear hobbing. The same hob can process gears with any number of teeth with the same modulus. The pitch accuracy of the gear cut by the hob is high, because each tooth of the gear is cut by the same cutter tooth of the hob, so the pitch error of the hob does not affect the pitch accuracy of the workpiece (but the indexing error between the heads of the multi head hob will affect the pitch error of the gear).
Most gears in machinery are machined by gear hobbing, or supplemented by other finishing methods. In principle, gear hobbing is equivalent to the spatial close meshing of a pair of staggered shaft helical gears. The micro research on the cutting mechanism of gear hobbing is not perfect. In the past, it only stayed at the level of experimental research. The main reasons are as follows:
(1) The cutting process of gear hobbing is very complex. Not only the cutting state of each tooth of hob varies greatly from each other, but also the cutting state of the same tooth changes greatly at different moments;
(2) The gear hobbing process is very sensitive to the influence of external conditions (including cutting specifications and various error factors). In the gear hobbing process, various errors from cutting tools, machine tools, fixtures and gear blanks are reflected on the processed gear to varying degrees, and the sources and action laws of various influencing errors are different, This brings some difficulties to the detailed study of gear hobbing cutting mechanism, and these conditions affect the accuracy of gear hobbing machining to varying degrees;
(3) The shape and structure of hob are different from general tools. It is the most complex of all cutting tools, and its cutting characteristics and wear characteristics are also different from general tools. In-depth research in the actual production of the factory has a very effective guiding significance for improving efficiency and reducing costs.