During gear hobbing, the gear hob axis and workpiece axis must conform to a certain axis intersection angle. Therefore, the installation angle of gear hob should be adjusted γ When installed at an appropriate angle, the size of the installation angle is determined by the size and direction of the spiral angle between the gear hob and the workpiece.
When the gear hob processes the straight cylindrical gear, the installation angle of the gear hob is the spiral rise angle of the hob, that is:
When machining helical cylindrical gear with gear hob:
Where:
γ 0 – spiral rise angle of gear hob (RAD);
β — Helix angle of indexing circle of machined gear (RAD)
When machining helical cylindrical gear with gear hob, when the helical direction of gear hob is consistent with that of helical gear, take “-” sign in the formula; When the helical direction of gear hob and helical gear is opposite, take “+” in the formula. The installation angle of gear hob shall be compatible with the size and direction of spiral angle of workpiece indexing circle.