SFT method is applicable to the processing of spiral bevel gears with transmission ratio greater than 2.5, which means that the large wheel is processed by forming method and the small wheel is processed by knife inclination method. When machining large wheels by forming method, x, Y axes and workpiece axes do not need to be linked. The machine tool has simple structure and high gear cutting efficiency.
As shown in the figure, the cutter head coordinate system for machining large wheel by forming method is shown, and the blade forming surface equation is:
Where:
( u, θ) —— Determine the parameters of the moving point n on the blade forming surface
RC — radius of cutter head tip, RC = R0 ± W1 / 2, R0 is the nominal radius of cutter head, W2 is the tool tip distance
Am — tooth shape angle, M = (I, e), I represents inner blade, take “+”; E means outer blade, take “-“
The blade tip parameter um0 is:
Where:
Um0 — parameter u corresponding to tool tip point.