According to the stress analysis of gear hobbing hob, further analyze the stress of gear hobbing hob shaft, as shown in the figure. From the stress of gear hobbing hob shaft, it can be seen that all parts of the torque on the gear hobbing hob shaft at a certain moment are the same. Therefore, the instantaneous torque on the shaft can be measured to determine the instantaneous force of the acting force on the shaft.
The cutting load of each row of cutter teeth of gear hobbing hob is different at different moments, and the area moment reflects the circumferential force borne by each row of cutter teeth:
(1) From the curve, the following rows of cutter teeth bear large torque, and on the whole, the change of torque borne by each row of cutter teeth is not great;
(2) For each row of cutter teeth, there is a large cutting load in the cutting angle range of about 10 ° ~ 23 °, and the curve drops sharply to zero in the range of 26 ° ~ 24 °. This shows that when the cutting angle is about 0 ° ~ 10 °, the cutting amount of gear hobbing hob is small and mainly completes the work of enveloping tooth profile. Remove a small amount of metal, and within the range of 10 ° ~ 23 °, the gear hobbing hob will cut most of the allowance, while within the range of 24 ° ~ 26 °, it is the time when the cutter teeth exit the cutting state, so the load decreases sharply;
(3) The whole cutter presents small periodic changes in 360 ° angle, the cutting load increases continuously, then maintains a high load state, and finally drops sharply and exits the cutting state;
(4) In the process of gear hobbing, the wear condition of gear hobbing hob teeth depends on the distribution of tool tooth load. Due to the uneven cutting load and bad cutting shape of each tool tooth during gear hobbing, the wear condition of each tool tooth of gear hobbing hob is very different. The chip shape formed during gear hobbing cutting makes those cutter teeth that are most unfavorable to cutting wear first, and other cutter teeth often wear very little;
(5) In gear hobbing machining, the main errors affecting the cut gear are the manufacturing and grinding errors of gear hobbing hob;
(6) When machining small module gears, the left and right tooth profiles are often asymmetric, which is caused by the non tangent of the axial position of the gear hobbing hob;
(7) The original tooth profile error of gear hobbing hob is produced by the manufacturing of gear hobbing hob, which has a great impact on the cut gear, because the tooth profile of the cut gear is mainly enveloped by the side edge of gear hobbing hob;
(8) The cumulative error of the chip holding groove and the non axial error of the rake face of the gear hobbing hob cause the change of the axial tooth pitch of the gear hobbing hob, resulting in the tooth shape error of the cut gear.
The comprehensive action curve of gear hobbing machining error is sinusoidal distribution, which is mainly due to the large radial runout of the indexing cylinder to the axis of the inner hole during the manufacturing of gear hobbing hob, resulting in eccentric installation or large runout error of the tool shaft itself.