Self-centering device for grinding drum brake and using method thereof

The invention relates to the field of brake grinding equipment, in particular to a self-centering device for grinding a drum brake and a using method thereof. The self-centering device comprises positioning seats, positioning rings, spring pressing plates, springs, bolts and a grinder; the grinder is provided with a hydraulic pulling rod, conical shaft heads and a pressing plate, and the positioning seats are mounted on the conical shaft heads of the grinder in a sleeving mode; each positioning ring is integrally composed of a first cylinder section on the upper portion and a conical section on the lower portion; second cylinder sections matched with the inner diameter faces of the positioning rings are finish-machined on the outer diameter faces of the positioning seats, positioning shoulders are formed on the outer diameter faces of the positioning seats, longitudinal through holes are formed in the positioning shoulders, and the bolts penetrate into the through holes to be in threaded connection with threa