Patent GB-1093182-A (GB)
Title: Mills for comminuting material
Inventor: BICK DAVID EWART
IPC: B02C17/24
Filed: 1964-05-01
Abstract: 1,093,182. Tube mills. DOWTY ROTOL Ltd. April 28, 1965 [May 1, 1964], No. 18199/64. Heading B2A. [Also in Divisions F1 and G3] A tube mill comprises a liquid pulse generator, a liquid pulse receiver, a connecting means to permit liquid pulses to be transmitted from the generator to the receiver, a container 11, Fig. 3, for the material to be comminuted, moved by the receiver by each liquid pulse, and a fluid compression device viz. a further generator and receiver to return the container to a position from which it is movable by the receiver. As described the mill cylinder 11 is supported in a mounting member 12 by sets of horizontal and vertical springs 13, 14, Figs. 2, and actuated by four liquid pulse receivers including cylinders 17, 18 on a vertical axis. Pistons 19, 21..23 are mounted in the cylinders and connected by units 24.. 27 to flanges surrounding the mill. Vibratory movement is imparted by a pulse generator unit which comprises a block 32 having bores 34.. 37 around a motor driven shaft, and containing pistons 38, 39, 41, 42, Fig. 4. The pistons engage a swash plate 43 pivoted to the shaft and angularly adjustable by movement of a spring-loaded piston 54 and co-operating linkwork. Pulses are generated sequentially so that a gyratory motion is applied to the cylinder 11. A priming pump 66 maintains positive pressure in the interconnecting pipes 62.. 65. The system is tuned to resonance by variable capacity chambers 72. .75 connected to the pipes 62.. 65, and containing pistons 76. .79 actuated by threaded rods 81..84 turned by a gear motor 85. The amplitude of movement of the mill cylinder 11 in the direction of the axis of the cylinders 15, 16 is sensed by a device including an annular pumping chamber 88 between the cylinder 16 and piston 21; an inlet 89 and an outlet valve 92 discharging to a pressure signal pipe 93 which discharges via a restrictor 94 to a low pressure pipe 91 connected to a reservoir 67. Pressure in the pipe 93 is a function of the amplitude. A similar device for sensing amplitude on the other axis comprises a chamber 96, an inlet valve 97 connected to the pipe 91, an outlet valve 98 discharging to a second pressure signal pipe 99, a restrictor 101 ganged to the restrictor 94 together with an accumulator 102. The signal pipes 93, 99 are connected to chambers 104, 105 at opposite ends of a valve 106. The spool 107 of this valve is centred by springs and moved under a predominating pressure in the chamber 104 or 105 to control operation of the gear motor 85. If the inertial reaction or mass of the charge in the mill cylinder changes during continued operation, the devices generate signals in the pipes 93, 99 to restore the system to vibrations of equal amplitude in both directions. The signal pipes also control the piston 54 to vary the angle of the swash-plate 54 and thus the amplitude of movement of the mill. In a second embodiment a mill cylinder 121, Fig. 8, which may be supported on a vertical or horizontal axis is gyrated by a pulse generator 124, hydraulic cylinders 138, 139, 143, 144 and pistons 141, 142, 145, 146 and the capacity chambers 133.. 136 which are constructed as an assembly without connecting pipes. The amplitudes of movement of the mill cylinder in perpendicular directions are sensed by accelerometers 152, 153, Fig. 9 and a difference signal derived, amplified at 162 and used to control the speed of the drive motor 122, so that the amplitudes of movement of the mill cylinder are restored to equality. The signals are also amplified at 169 and operate an electromagnetically controlled valve 174 from which a line 177 supplies fluid to actuate a piston 179 which controls the angle of the swashplate of the generator and thus limits the amplitudes of movement of the mill cylinder. The mill may be modified by being actuated on one stroke only, by providing only two cylinders in the pulse generator. There may also be three generators operating receivers arranged on axes mutually inclined at 120.