From the point of view of the purpose of designing super large modified gear (medium hard tooth surface and medium precision), because the machining accuracy of profiling method is low, which affects the performance of transmission, no matter how the marking accuracy of gear is, profiling method should not be used, envelope method should be used, so that the quality of tooth surface and cutting efficiency are also high. If conditions permit, the comb method should be used. Because the gears with medium hard tooth surface (330 ~ 420 HB) are made of high speed steel tools, the comb method is relatively easier than the hobbing method. Because the comb teeth are processed tooth by tooth, the machine can be stopped and the tools can be sharpened in the cutting process, giving full play to the advantages of the comb technology.
In addition, the use of positive rake hob can significantly improve the cutting performance and durability of the cutting tool, increase productivity, and consume less power and tooth surface roughness.
In order to further improve the durability or cutting performance of hobs, hobs made of high-performance materials can be used, such as cryogenic treatment, surface or edge strengthening treatment, etc.
From the above discussion, this paper clarifies the “focus” of the problem caused by hobbing super large modified gear with standard hob, so as to realize that this kind of gear can be processed by all methods of involute gear, because the modification coefficient is particularly large, it will bring some special personality, and pay attention to the difference of segmented Hobbing with standard hob with insufficient cutting edge length, which is the same as hobbing other gears, so it is necessary to save time It reduces the cost of expensive cutting tools, and is easy to operate, but it has low efficiency and certain economy.