New Possibilities of Tooth Cutting by Running Cutter Heads

Abstract

The traditional method of worm and spiroid gearwheel tooth machining is both convenient and understandable for manufacturers and hard-to-improve with regard to increasing its production efficiency, control of contact localization, terms and cost of production preparation, and limitations of making gears with the relatively small gear ratios. The manuscript considers the possible alternative—tooth cutting by multi-tooth flying (running) cutter that is proposed to be made assembled, equipped with carbide inserts and called the running cutter head. In order to provide this possibility, it is proposed to calculate the machine-tool setting by the method well acknowledged to be applied for designing machine-tool settings for hobs with the small number of threads. It is noted, that the most general relative arrangement of the machine-tool and operating meshes is used in this method; it gives possibility to change parameters and the level of surface modification within a wide range. In order to provide the application of the multi-cutter running head, it is proposed to increase the number of threads of the generating worm as compared to the gear worm and increase the tool diameter. The performed numerical calculations showed that for the case of the worm gear this approach can be applied with minimum limitations; and for the case of the spiroid one the limitations are unfavorable tooth modifications and tooth undercut. To overcome the first limitations, it is proposed to apply the tool feed with the variable velocity. It is easily arranged for CNC machine-tools; and it allows for applying the method not only for multi-thread gears, but for the single-thread ones (therefore, for any type). The second limitation can be lowered by choosing the parameters of the conjugate gear with a certain reserve for the undercut. Due to a number of advantages, the proposed method can become competitive, especially, for worm-type gears with the relatively small gear ratios and for bevel gears produced in low series.