Expanding device for flexible gear inner hole and clamping method thereof

The invention discloses an expanding device for a flexible gear inner hole and a clamping method thereof, and particularly relates to the technical field of machining assistance of a flexible gear of a harmonic reducer. The invention discloses the expanding device for the flexible gear inner hole and a clamping method thereof. A lead screw assembly comprises a lead screw and a lead screw nut arranged on the lead screw; a tensioning assembly comprises a step mandrel and a tensioning sleeve assembly, wherein the step mandrel is provided with at least two step shafts with different diameters, and the step mandrel is sleeved with a tensioning sleeve assembly; the tensioning sleeve assembly comprises an expansion sleeve and an elastic ring, wherein the expansion sleeve is composed of a pair of semicircular expansion sleeves which are separated from each other; the step mandrel is sleeved on the lead screw nut, and the semicircular expansion sleeve is sleeved on a step shaft of the step mandrel through the elastic