GB1396153A - Variable nip press having rolls maintained on parallel axes - Google Patents

Abstract

1396153 Pressing out moisture IMPROVED MACHINERY Inc 26 May 1972 [22 June 1971] 24987/72 Heading F4G [Also in Division B1] Liquid is removed from suspensions such as pulp and effluent sludge by forcing it through a plurality of pipes 20 (Fig. 4) and vat 10 between two porous rolls 40, 42 which are rotated in opposite directions about parallel axes, the hubs 56 of roll 40 being mounted on slidable blocks 62 (Fig. 3) and the hubs of roll 42 being mounted on fixed blocks 64. The liquid is pressed through the circumferential walls of the rolls, and the filtrate drains through conduits 58 at each end of the rolls. The pressed solid material is removed from the rolls by doctor blades 46, 48, and discharged from conduit 24 by rotary screw 26. Tubes 70, which are filled with pressurized air from source 74, exert constant biasing forces through blocks 62 on the ends of roll 40 to hold the latter spaced away from roll 42 by nip 44. Blocks 62 are connected by tie rods 66 to a pair of platens 68 and link (lever) systems 82, 84, each comprising four links, the links 86 (Fig. 5) of the two systems being rigidly connected by a rod 166, and the arrangement being such that, when the device is actuated by the action of compressed air from tank 138 on pistons 128 in cylinders 126, the rolls 40 and 42 are urged towards one another but the axes of the rolls are maintained parallel. In the event of the passage of foreign (tramp) material longitudinally offcentre through nip 44, the movement of the end of roll 40 most adjacent to the tramp material away from roll 42 automatically causes commensurate movement of the links of system 82 or 84 which immediately actuates the rod 166 to provide identical movement of the other system. If extremely large tramp material enters the nip 44, the switch 160 (Fig. 3) is tripped by the third link 98 whereby solenoid-operated valve 152 is shifted by spring 156 to exhaust air from the tank 138 through conduit 142 so that roll 40 moves away from roll 42 and substantial damage is prevented.