Double herringbone gear in-phase processing method

The invention discloses a method for preparing double cross gear, belonging to mechanical process technology. Said double cross gear is formed with left-and-right involutes helicoids, the cross gear center is the cross point of left gear central line and the right one; if the two cross gear is the same phase, the cross gear center 3 on graduated cylinder gear 1 and cross center 4 on gear 2 are at the same bus wire; and if projected on gear graduated circumference, the two cross gear center 3 and 4 are at the same circumferential position; and if the cross gear center 3 and 4 are at different phase, the cross gear 1 and 2 are at the same phase, then s1 equals to s2, and the center distance of left gear and right gear of two cross gears are equal, 11=12; clamping double cross gear blank on digital control milling machine for preparation.