Patent ID: 7044691

Claim:
A forming method for milling teeth of variable tooth worms, comprising the following steps: on a multi-axis simultaneously-working CNC machine-tool, a first moving coordinate system {σ 1 (φ 1 )[O 1 ; i 1 (φ 1 ); j 1 (φ 1 ), k 1 (φ 1 )]} is correlated to the worm blank of the VTW worms, wherein the worm blank of the VTW worms rotates around k 1 (φ 1 )-axis at angular speed |ω 1 |; a second moving coordinate system {σ 2 (φ 2 )[O 2 ; i 2 (φ 2 ); j 2 (φ 2 ), k 2 (φ 2 )]} is correlated to the milling cutter, wherein the milling-cutter rotates around k 2 (φ 2 )-axis at angular speed |ω 2 |, |ω 1 |/|ω 2 |=i 12 and i 12 is a constant; the feed motion of the milling cutter comprises the radial shift along the i 2 (O 2 )-axis and the peripheral shift around the k 2 (φ 2 )-axis; the equations of each cutting edge of the milling cutter are given as follows: x 2 =u y 2 =r b −v sin β z 2 =v cos β where, u, v are the parameters of a generatrix plane Σ of the variable tooth worms tangent to an imaginary cone; β is the inclination angle of the generatrix plane Σ relative to the axis of the imaginary cone; r b is the radius of the main basic circle of the cutter body; x 2 , y 2 , z 2 are the coordinate values of the cutting edge on the generatrix plane, in which when the center distance between the worm blank and the milling-cutter is from 80 mm to 500 mm, the value of u is from 51 to 378, the value of v is from ±19.4 to ±122, and the value of r b is from 19 mm to 173 mm; and βis greater than 0° and less than or equal to 30°; and shifting of a cutting edge of the cutter on the inclined generatrix plane in spatial locations about the milling cutter forms a cutter that will form the tooth flank of the variable tooth worms in the worm blank.