Metric Buttress Thread Milling and Turning on CNC Machines

Abstract

Present-day catalogues of tool manufacturers do not contain information on milling cutters for planetary milling of metric buttress threads with nominal pitches on computer numerical control (CNC) machines. This paper presents the results of theoretical and experimental investigation of buttress threads cutting on 3-axis CNC machines. The theoretical investigation is based on the kinematic method of envelope determination. This analytical solution has been verified by the solid modelling method and experiments. It has been proven that standard metric buttress threads with nominal pitches cannot be cut by planetary milling on the 3-axis CNC machines. At the same time, metric buttress threads with small pitches can be produced; such cases are described in this paper. However, thread surface quality after planetary milling is problematic. The technology of initial productive thread milling followed by final thread turning is suggested to obtain metric buttress thread using a new type of milling- turning cutters. The results of this investigation can be useful for industrial plants if buttress thread milling on 3-axis CNC machines is necessary.