A Method for Generating Helical Surface of the VPA Hob on a CNC Worm Grinding MachineVan-The Tran, Ruei-Hung Hsu, Shih-Sheng Chen and Yu-Ren WuMATEC Web Conf., 95 (2017) 04002DOI: https://doi.org/10.1051/matecconf/20179504002