Self-centering dimensional clamping tool and clamping method for large conical surface rotary body part

The self-centering shape-maintaining clamping tool is structurally characterized in that a workpiece (4) is clamped between a cover plate (3) and a base (6), the lower end of a rotatable threaded rod (9) is sleeved with a machine tool centering shaft hole (7), the upper end of the rotatable threaded rod (9) penetrates through the cover plate (3), and a compression nut (1) is installed at the end of the rotatable threaded rod (9); the base (6) penetrates through the rotatable threaded rod (9) to be fixed to a machine tool table top, the brittle and hard pin bush (8) is arranged between the rotatable threaded rod (9) and the base (6) in a sleeved mode, an inner cylinder wall is arranged at the position of a center hole of the shape maintaining centering plate (5), and the inner cylinder wall is rotatably placed in the brittle and hard pin bush (8). The rotatable threaded rod (9) is connected with a center hole of the shape-maintaining centering plate (5) in a reverse-rotation threaded mode, and the compression