Truncated cone-shaped sleeve dip pipe for RH vacuum finery

The invention discloses a truncated cone-shaped sleeve dip pipe for a RH vacuum finery, belonging to the technical field of external refining of molten steel. The truncated cone-shaped sleeve dip pipe comprises a riser and a downcomer; the area of the upper bottom surface of the riser is greater than the area of the lower bottom surface of the riser, and the areas of horizontal cross sections of the riser gradually increase from bottom to top along an axial direction; an outer sleeve is a truncated cone-shaped hollow pipe, and the area of the upper bottom surface of the outer sleeve is greater than the area of the lower bottom surface of the outer sleeve; the top of a central pipe is fixedly connected with the outer sleeve via a fixed beam, and the central pipe and the outer sleeve have a same axial center; the central pipe is the riser and is a truncated cone-shaped hollow pipe, and the area of the upper bottom surface of the central pipe is greater than the area of the lower bottom surface of the central pi