Patent GB-221743-A (GB)
Title: Improvements in or relating to pulverising mills
IPC: B02C15/02
Filed: 1924-03-18
Abstract: 221,743. Imray, O. Y., (International Combustion Engineering Corporation). March 18, 1924. Roller-and-ring mills.-In a mill with rollers operating within and against a stationary ring and having ploughs rotating over the bottom of the mill to deliver material between the. rollers and ring, an air draught passing through inlet ports below the ring and upwardly through the mill to remove pulverized material, the bottom of the mill between the air ports and ploughs and under the ploughs is sloped downwardly toward the centre of the mill. The air ports 13, Figs. 1 and 2, are formed between webs connecting the base member 10 and the annular member 11 to which the grinding-ring 18 is secured and the bottom surfaces 31 of the parts are sloped inwardly and downwardly. Preferably the bottom surface 16<a> of the circular air trunk 16 to which the air is returned from the separator by a pipe 17 is also sloped downwardly towards the ports 13. The ploughs 23 which revolve with the, pulverizing-rollers 19 travel over a path at some distance within the inner ends of the ports 13, and the portion 32 of the bottom member 10 is also preferably inclined. The surface 33 between the ploughs 23 and the ports 13 is also inclined downwardly and inwardly, and may be given a sharper pitch than the surfaces 31. 32. The webs 12 are arranged obliquely to the radial lines of the mill and formed so that the inner portions of the ports 13 are of substantially uniform Gross-section while the outer portions or mouths are flared outwardly. The annual portion 11 of the base casting is of smaller diameter than the bottom member 10, and the webs 12 project diagonally from the member 11 downwardly and outwardly to the edge of the member 10. The ring 18 has a wedging fit with the member 11 and is secured in place by wedgeblocks 38 arranged between the upper surface of the ring 18 and a ring 39 bolted to the member 11, the blocks 38 being drawn back by bolts 41. The upper casing 14 to which the outlet pipe 15 is connected is bolted to a flange on the ring 39. One side face of each web 12 lies in an oblique plane and slants forwardly and upwardly in the direction towards the air current passing through the trunk 16, and the angle between this face and the surfaces 31, 32 is preferably slightly less than a right-angle. The other side of the web is formed with two surfaces making an obtuse angle to each other, the inner surface being parallel with the surface of the adjacent, web while the other surface slants away in the direction toward the outer edge of the member 10. The air passing through the trunk 16 impinges upon the surfaces of the webs and is crowded through the narrowed inner ends of the ports 13 in streams which tend to keep the parts cleared of loose material. The trunk 16 has a maximum height at the place where, the air enters through the pipe 17 and is of progressively diminishing height for the rest of its circumference. The ploughs 23 are secured to a sloping flange 52 at the bottom of a sleeve 53 which is secured by its flange 54 to a flange 55 on the roller carrier 21 keyed to a. vertical shaft 22 driven by bevel gearing 29, 30 from the driving-shaft 27. The body 58, Fig. 7, of each plough is bolted to an inclined peripheral projection 56 on the apron 52, a recess 60 in the body fitting over a rib 61 on the projection. Each plough has a removable hard-steel share 62 secured by screws passing through flanges 64, 65 on the plough body and share. The plough has a curved rib 66 at its outer edge and a short rib 67 at the upper end of its inner edge. The feed-shoot 68, Fig. 1, delivers the material above the carrier 21, and at one side of the shaft 22, and shoots 72 lead from the openings 71 between the forked arms 70 to which the roller journad housing 20 are pivoted, towards the ring 18. The shaft 22 is supported on a thrust bearing comprising a casing 74, ball races 75, 76, and balls 77, and the bottom of the casing has a socket 79 to receive a ball 80 on the end of an adjusting-screw 81 threaded into a member 82 supported in a socket 84 in a plate 85 secured to the foundation 86.