Patent GB-957869-A (GB)
Title: Tablet press
IPC: B30B11/12
Filed: 1960-12-29
Abstract: 957,869. Tablet presses. PROCTER & GAMBLE Ltd. Dec. 29, 1960 [Dec. 31, 1959], No. 44668/60. Heading B5A. A press for making tablets e.g. detergent tablets, comprises a drum 17 rotatably mounted in a frame with its axis horizontal, and having a plurality of radially extending bores 34, each with a piston 35 located so as to leave a die cavity 83 in the drum, a hopper 82 to fill the die cavities, and a plurality of outer dies 89 mounted to close the die cavities during compression of the material therein, the pressure being applied by outward movement of the pistons 35 caused by engagement of cam rollers 42 on a stationary central cam 46, the pistons and outer dies being rotated slightly, about the axes of the bores 34, during and after compression to free the moulded tablet. The drum of Fig. 4 is rotated in a clockwise direction on a hollow shaft 14, and starting from position A the end of the piston 35, which is fitted with a die 36, is held below the outer surface 29 of the drum 17 by a return cam roller fitted in an inward extension (not shown) of the piston and engaging on the inside of a cam 53 and a cam link 54. The die cavity 83 is filled with powdered material G as it passes under the hopper 82, a wall 85 preventing escape of material which works back under the wall 84. The piston is raised slightly as it passes under a wall 85a of the hopper by engagement of the roller 42 with a slidable cam piece 58, to level off the charge in the die cavity. The cam piece 58 is adjustable vertically to control the size of the die cavity 83 by rotation of a hand wheel (not shown) fixed to the end of a shaft 72, which causes rotation of a screw threaded sleeve on the inside of a gear-wheel 74 through a worm 71, which in turn'moves a shaft 76 up or down. The return cam roller then engages a cam 59 which retracts the piston 35 slightly and excess material is removed by a suction pipe (not shown). A plurality of outer dies 89 are mounted on roller chains 90, passing round sprockets (not shown), the path of the chains being shown in Fig. 4. An outer die engages with each die cavity 83 and is held in contact therewith by engagement of rollers 98 with a fixed plate 101. The material in the die cavity 83 is compressed, as the cavity passes between positions B and C of Fig. 4, by radial outward movement of the piston 35 on the cam 46. The compression pressure may be adjusted by rotation of a hand wheel (not shown) attached to the end of a shaft 64, causing rotation of a threaded shaft 67, through a worm 63 and a gear-wheel 66, which moves the part 48 of the cam 46 about a pin 49. The tablet T is ejected on to a conveyer (not shown) by a hump on the cam 46 at the position D of Fig. 4. Just before reaching position C of Fig. 4 the piston 35 is rotated slightly about its axis by engagement of a shaft 45 fitted at its lower end (Fig. 6) with a cam 111 on the shaft 14. The piston is returned to its original position by a cam 113, just after passing the position C of Fig. 4. The outer dies 89 are rotatable in their carriages, rotation being effected by cams (not shown) fixed to the plate 101, at the same time as but in the opposite direction to the rotation of the pistons 35 (Figs. 7 and 8, not shown). The roller chains 90 are driven by sprockets fitted on each side of the drum 17 (Fig. 1, not shown). Specification 957,868 is referred to.