The invention discloses a novel method for
machining a last blade lock notch groove through a planing and slotting
machine, relates to the technical field of
machining of rhombic lock notch grooves of
steam turbine rotors, and aims to solve the problems that according to an existing last blade lock notch groove method, when an
acute angle is machined, a tool is prone to breakage, so that the lock notch groove is punctured, and the perpendicularity of the lock notch groove is poor. The method comprises the following steps that firstly, a to-be-machined lock notch rhombus and
quadrilateral CAD drawing is drawn and comprises to-be-machined parts at the left end and the right end of a lock notch and a feed space, and each to-be-machined part is divided into an acute triangle part, a rectangular part and an obtuse triangle part; 2, a tool is selected, and a rough slotting tool is selected as the tool; the
machining method is used for machining the locking groove of the
tail blade of the
steam turbine rotor, the machining allowance is sequentially reduced through rough machining, semi-finish machining and finish machining, the machining efficiency is ensured, and the possibility that the cutter is broken when the
acute angle is machined is also prevented.