Stoffmuehle

1,123,486. Defibrating apparatus. BELOIT CORP. 21 Jan., 1966 [4 Feb., 1965], No. 2874/66. Heading B2A. Defibrating apparatus 10, Fig. 1, for wood, sugar cane, straw, prairie grass, waste paper or rags, comprises a housing 13 containing horizontal upper and lower spaced defibrating discs 17, 18, which are arranged to have a prebreaking zone defined by ridges on the discs, an intermediate defibrating zone defined by intermediate annular portions and a final defibrating zone defined by outer ridges on facing surfaces of the discs. As described, the upper disc is fixed and the lower disc 18, rotated by a shaft 23 and an induction motor 11. Fibrous material is supplied via an open trough 19 through an inlet 15 and a chemical dilution agent may be supplied via a pipe 27, under control by a valve 28 which may be manually controlled or regulated automatically in response to a signal from a quality-sensing device or a horsepower-measuring device connected to the drive motor. Steam is permitted to escape without interfering with the feed of raw material by providing an annular chamber 30, Fig. 3, directly over the inlet 15, with its upper part closed by a ring 31. Steam accumulating in the chamber 30 escapes via a duct 33 into a hood 34. The material fed in is distributed by a member 36 having vanes 38, to the prebreaking zone. The lower disc has grooves which fill with fibrous material in operation, so that it presents alternating metal and fibrous surfaces to the upper disc 3 and are also of twice the width of the respective surfaces of the upper disc. The grooves of the upper disc are of uniform cross-sectional area and dams 69, Fig. 7, are provided to retain fibrous material, having a substantially less height than the grooves 60. The dimensions of the grooves and ridges of the upper plate in the final zone 70, Fig. 8 are equal to those of the grooves and ridges in the intermediate zone 54 and are of constant height, as are the ridges on the outer annular portions 72 of the lower plate 43. As the material leaves the final defibrating zone it is thrown outwards by impellers 83 to an exit port 22, Fig. 2. The shaft 23 is mounted in bearing assemblies 24, 25 formed by two pairs of ball bearings 87, 88, which are secured in axially movable upper and lower housings 89, 90. To axially displace the rotor 18 for adjustment of the refining gap 21, the lower bearing assembly is connected to a motor-driven screw jack 96 by a shaft 97. The refining gap 21 is manually adjust