The present invention relate to the field of involute gears. Disclosed are a gear-cutting hob and a designing method therefor, and a non-fully-symmetric involute gear and a machining method therefor. In an axial tooth profile of a gear-cutting hob (100), an involute segment AB and an involute segment FE are non-fully symmetric about an axis III, the radius of curvature of a tooth-root curving segment is not equal to the radius of curvature of a tooth-root curving segment EG, and the tooth-root curving segment BG and the tooth-root curving segment EG are asymmetrically arranged about the axis III. In a rolling-cut gear (390) and a non-fully-symmetric involute gear (300) manufactured by machining using the gear-cutting hob (100), left and right tooth-root curving segments of a tooth profile of an end-face tooth space of the gears also have different radii of curvature and are asymmetrically arranged about the axis III. Different high tooth-root curvature strengths can be obtained at left and right sides of teeth of the non-fully-symmetric involute gear (300), and the non-fully-symmetric involute gear (300) is quite suitable for respectively meshing with two different gears by means of left and right tooth surfaces.
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