Patent GB-761178-A (GB)
Title: Improvements in grinding apparatus for particularly for fibrous materials
IPC: B02C7/14
Filed: 1954-07-09
Abstract: 761,178. Disc mills. AKTIEBOLAGET DEFIBRATOR. July 9, 1954 [July 15, 1953], No. 20117/54. Class 59 [Also in Group XXXIV] A grinding apparatus for breaking up fibrous and other material and comprising a stationary grinding disc 24 and a rotatable grinding disc 22 carried by an axially-displaceable shaft 12 includes a pressure fluidactuated motor 98 comprising a stationary casing 100 and an axially-displaceable piston 102 to produce a compressive pressure acting on the grinding disc 22 while relieving the shaft 12 for a substantial part of its length between the motor and the grinding disc 22 from said pressure. The shaft 12 is coupled at 18 to a co-axial motordriven shaft and is supported by bearings 14, 16 which are axially displaceable together with the shaft. The bearing 14 is adapted to absorb radial load and the bearing 16 to absorb both axial and radial loads. The bearing 16 is kept under continuous axial pressure by means of an axial thrust bearing 60 the outer ring 68 of which contacts a stationary ring 54 through a pre-compressed conical cup spring 70 and a sleeve 72. The piston 102 has secured thereto an externally screwthreaded sleeve 120 which has threaded thereon an axially-movable annular member 122 which abuts an annular member 140 provided in a cover 134 sealing the slidable housing 73 of the bearing 16. The sleeve 120 also has threaded thereon a ring 130 from which an annular plate 128 is spaced axially. A number of circumferentially-spaced bolts 132 pass with play through the ring 130 but are threaded into the plate 128 and into the cover 134. The bolts 132 compress springs 136 abutting against the ring 130 thus eliminating the effect of play between the threads connecting the members 102 and 134. An annular spacing member 58 is located between the bearing 16 and a shoulder 56 on the shaft 12. A manually-operable traverse shaft 148 is provided with a worm 146 co-operating with a worm wheel 144 rigidly secured to the piston 102. By turning the shaft 148, the piston 102 is rotated to displace the member 122 axially and the latter member in its movement entrains the bearing housing 73 and the grinding disc 22 connected thereto. The axial movement of the grinding disc 22 is indicated by a measuring instrument 156. The grinding discs 22, 24 are bolted respectively to a rotor disc 78 and to a stationary member 88 to which members are also bolted grinding discs 82, 90 located within the discs 22, 24. The grinding discs are enclosed by a casing 96 comprising central parts formed integrally with the member 88 and upper and lower covers bolted to the central parts. In operation, material to be ground is supplied to the grinding discs through a channel 94 and pressure oil is fed into the chamber 106 through an inlet 112. The oil pressure acts on the piston flange 104 and is transmitted through the parts 120, 122, 140, 134, 73, 16, 58, 78 and the grinding disc 22 to the material. If hard objects should find their way between the grinding discs, the piston 102 is'moved to the left by admitting pressure oil to the inlet 114. Specifications 706,384 and 761,179 are referred to.