Gear shaping, a widely used machining method for circular gears, was generalized to noncircular gears in recent works using a 3-linkage machine tool. As the pitch curve normals of noncircular gears change constantly in processing, angles may exist between the pitch curve normals and the cutter relieving direction, bringing in turn cutter retracting interference.
Regarding this, the paper proposes a 4-linkage shaping method. Through linkage motion of 4 machine tool axes, noncircular gear pitch normals are along the cutter relieving direction, avoiding completely cutter retracting interference. On such basis, a mathematical model is first established, the cutting process is then discussed and a cutting experiment is finally carried out, proving the validity of the proposed method.