The design parameters of gear hobbing hob for automobile gear processing are complex, mainly including outer diameter, total length, inner diameter, addendum height coefficient, addendum arc radius, contact angle thickness and height of gear hobbing hob, excessive tooth shape angle, addendum fillet, front angle, side edge back angle, hob straight diameter, hob head number, hob groove number, hob length, etc, According to the importance and experience of practical use, this chapter discusses six aspects: front angle, rear angle of side edge, hob diameter, hob head number, hob groove number and hob length.
According to the processing characteristics of automobile gear products, the influence of gear hobbing hob design parameters on automobile gear processing efficiency and processing quality is studied. The main work is as follows:
- Based on the calculation of the designed back angle of the top edge and the radial back amount of the gear hobbing hob, in order to improve the chip removal effect and improve the gear hobbing accuracy, this paper puts forward the hob angle design principle that the designed back angle of the top edge of the gear hobbing hob is 10 ° ~ 12 ° and the back angle of the side edge is not less than 3 °;
- The influence of gear hobbing hob diameter on cutting efficiency, cutting stroke and tool grinding times is studied, and the comparative cutting test of gear hobbing hob diameter is carried out. The results show that with the cutting speed of 100M / min, the machining efficiency of gear hobbing hob with diameter of 80mm is 28% higher than that of gear hobbing hob with diameter of 100mm;
- The research and test on the influence of the number of gear hobbing hob heads on the cutting efficiency show that the multi head gear hobbing hob is not suitable for using a large axial cutting amount. With the increase of the number of gear hobbing hob heads, the cutting load of the cutter teeth increases, so a small cutting amount should be used; Under the condition of high-speed cutting, the use of multi head gear hobbing hob is a way to improve efficiency, but the use of multi head gear hobbing hob will increase the pitch error;
- The research on the groove number of gear hobbing hob shows that using multi groove gear hobbing hob can significantly improve the tooth profile accuracy of the cut gear, increase the groove number of gear hobbing hob by one time, and reduce the theoretical envelope tooth profile error of multi groove gear hobbing hob by 3-4 times. Based on this, the design principle of groove number of gear hobbing hob is put forward;
- The length of gear hobbing hob in hobbing pre machining area and generating area is studied, and the calculation method of working length and tool shifting length of gear hobbing hob is put forward.