Patent GB-291952-A (GB)
Title: Improvements in or relating to machinery for grinding, mixing and like operations
IPC: B02C15/02
Filed: 1927-06-07
Abstract: 291,952. Wood, J. H. J. June 7, 1927. Roller-and-ring mills and apparatus; ball-andring mills; conical mills. - A method of and means for grinding and/ or mixing wet or dry materials comprises a machine having an annulus between stator and rotor elements, the latter having freely housed grinding members subject to centrifugal force, the volume of material treated and its degree of levigation being a function of the width of the annular space and length of grinding members. The stator 1 is cylindrical and the rotor 5 is mounted on a shaft 5 supported by bearings 3. The grinding rods or bars 7 are housed in recesses in the rotor and are capable of outward movement under centrifugal force. The material to be ground or admixed is fed into a hopper 11 having a controlled outlet formed on the cover plate 2 and is automatically drawn into the machine by fan-shaped projections 13 which force the material through apertures 12 cut obliquely in the periphery of the rotor flange 8 the effect of the entrance of the material being to depress the rods or rollers at that end so that they take up the inclined position shown in dotted lines in Fig. 1, the material as it is crushed being fed forward by the oncoming material, the air draught induced by rotation and also by the angle of the grinding bars; and the crushing or grinding effect is proportioned automatically to the particle size of the previous grinding result. The ground material is discharged through the orifice 19. The rotor may be cooled by passing a fluid through a pipe 17 affixed to a fluid tight gland 16 screwed to the casing and communicating with a centrally bored hole 14 in the shaft 4, the liquid passing into the rotor and out through a similar hole bored in the opposite end of the shaft 4. The stator may also be provided with a water jacket. In a modification applicable to grinding paint &c. the inlet hopper is attached to one end of the cylindrical cover 1 and the rotor is adapted to be reciprocated by a cam and cam race operated by gearing driven by the rotor shaft. The bars 7 may be of various shapes, for coarse and dry material a round rod is preferred whilst for wet grinding as for enamels an edged bar 7a or 7b is employed, Fig. 4. The material entering the slot housing the bar 7 suffers a supplementary grinding action and the sides of the slot may be made to converge toward the bottom, the point of convergence being eccentric to the centre of the shaft. In Fig. 6, the rotor 5 and stator 1 are tapered as also are the slots 29 and grinding elements 7, the machine being used in the vertical position for powdering coal, coke &c. In some forms an additional air stream may be introduced to the dry grinding mill, either at the feed end or intermediate thereto. and the outlet, and to prevent choking at the inlets rotary feeding devices may be inserted in the hopper. The volume of the material treated depends on the width of the annulus between the stator and rotor, and where the material merely requires to be broken down, such as in the case of moulding sand, the annulus width may be increased with corresponding increase in output. Where fine grinding and mixing is required the width of the annulus is diminished, further, the length of the grinding member determines to some extent the fineness of the material after treatment and the time period over which the treatment takes place. The first Provisional Specification states that a slot may be made in the ribs or bars and that they may have a pitch and be pivoted on the periphery. The second Provisional Specification states that plates and balls may he used instead of bars. The rotor may be partly cylindrical and partly tapered and either or both parts may be roughened. The balls, plates &c. may vary in size.