GB127589A - Improvements in and relating to Grinding Machines. - Google Patents

Abstract

127,589. Smidth & Co., F. L. May 30, 1918, [Convention date]. Ball-and-ring mills.-In mills in which grind. ing-members are arranged between two or more grinding-rings, one of which is divided into sections and is under pressure in order to increase the grinding action, the ground material is removed hy an air-current which passes between the grinding-members and the casing of the mill. In the arrangement described, balls c are located between an outer, preferably stationary, ring d and an inner ring c which is divided into radially movable sections carried by a rotating shaft a. The sections of the inner ring are mounted on loading-blocks f which can move radially under the action of centrifugal force in a holder b fixed on the shaft a. The balls e are arranged loosely in a holder h having a boss which surrounds' the hub of the holder b, adjacent balls being separated by arms i. Below the grinding-members is a bottom plate j which rotates with the holder b and has blades l on its underside so as to form a blower which draws in air through openings n in the mill casing k and forces a current of air between the casing and the outer ring d. The material to be ground is fed in through a central pipe p and is thrown by centrifugal force against the outer ring d, then falling between the rings and the balls. On reaching the plate j, the material is thrown against the casing k and is carried up by the air current over the grinding-members, on to which the coarser particles again fall, the finer material being carried hy the air current through an outlet q. The Specification as open to inspection under Sect. 91 (3) (a) states also that the grinding-rings may have relative movement in a vertical direction to secure uniform wear, and the outer ring may be slightly conical, so that a slight rotation about an horizontal axis is imparted to the balls. The loading-blocks f may be replaced by other means for producing radial pressure, viz. mechanical loading of various kinds, spring loading, tightening-devices, and means for creating pressure by air or liquid, and such means may act on either the outer or the inner ring, or on both. More than two grinding-rings may be used, and the inner ring. instead of being in sections, may be a single ring cut at one point only. The material may be raised from the plate j by centrifugal force, the plate then having a conical edge. This subject-matter does not appear in the Specification as accepted.