Abstract: In view of manufacturing problem of the spatial spiral tooth surface of the planar enveloping toroidal (TP) worm, a method of accurately turning TP worm using the standard slotting cutter on a general NC lathe was proposed. According to gear meshing principle and NURBS surface modeling, the digital tooth surface of TP worm was derived and reconstructed accurately. The spatial spiral trajectory was constructed by discretizing the tooth surface uniformly. The discrete points of the tooth surface were transformed into the turning plane with a rotational matrix, and the cutter location was obtained by offsetting the radius of tool tip along the normal direction of tooth profile. The precision turning program of TP worm was compiled according to the cutter location data and thread turning instruction. Finally, the feasibility of the method is verified through simulation cutting experiments. The research results show that the TP worm simulation machining using this method and the corresponding tooth surface discrete data has uniform tooth surface error and high precision, and the average absolute value of the machining error is about 0.14μm and 1.2μm; this method has high efficiency and high machining accuracy. It has higher guiding value for mass production of plane envelope toroidal worms.
Key words:  planar enveloping toroidal worm; reconstruction of tooth surface; NC turning; universal CNC lathe

TIAN Qian-hu, DING Shuang. Precision turning method of TP worm based on general NC lathe［J］.Journal of Mechanical & Electrical Engineering, 2021,38(10):1361-1366.