Patent GB-731600-A (GB)
Title: Improvements in or relating to machines for use in the production or covering of tablets and other articles
IPC: B30B11/08
Filed: 1952-01-30
Abstract: 731,600. Moulding tablets &c. HOLROYD & CO., Ltd., J., and STOTT, F. T. Dec. 15, 1952 [Jan. 30, 1952], No. 2464/52. Class 87 (2). A machine for making or covering tablets or other articles by compressing powder in dies in a continually-rotated die table (the powder constituting or covering the tablets &c.) has special means for feeding the powder, this means comprising a device that is continually rotated in one direction and has apertures that rotate therewith and register periodically with the rotating dies, each aperture moving at the moment of registration in the same direction as the registering die and conveying powder, tablets &c. into the die. Figs. 1 and 3 show a machine comprising a table 1 rotating continuously clockwise about a vertical axis 2 and having dies 3 to which powder is fed by a counter-clockwise rotating annular platform 13. The platform forms part of a central boss 22 which is rotated by gearing 15-18 from teeth 19 on table 1, and has circular apertures 14, which are preferably larger in diameter than the dies 3. Powder is fed on to the platform and fills the apertures. The platform rotates at the same peripheral speed as table 1, and as it rotates each aperture registers with a die and powder from the aperture falls into the die. The platform is disposed within and supported by a non-rotatable casing 10 which is slidable on a radial bed 11 against a spring 21, so that in case of obstruction a punch 4 or 7 may push the casing and platform away without damaging it. The punches are raised and lowered by cams, the lower punches having a final upward movement to C, Fig. 1, to discharge pressed tablets, which are swept off the table by an inclined fence 5. In a second machine, Fig. 6 (not shown), three such feeding devices are disposed around the table 1 and feed, one after another, three lots of powder, the lower dies descending in steps to leave room in the die for the powder and the three lots being pressed together as shown in Fig. 11. In a third machine, Fig. 14, for making a three-layer tablet such as is shown in Fig. 11, one rotary platform 38 having powder-filled recesses 50 is used to feed the middle layer and a hopper 40 feeds the top and bottom layers. The powder from the hopper is carried around by the clockwise-rotating table 36 to a filling station 48 where it drops into the die to form the bottom layer, this powder being confined between a stationary barrier 41 and a pillar 42 rotating with the table. The middle layer is then applied by the platform 38 and the top layer by the hopper 40. A fourth machine, Figs. 15 and 16, for coating preformed tablets comprises apertured rotating platforms 61, 63 for feeding powder and a similar platform 62 for feeding preformed tablets, platform 62 having flexible rubber strips 68 which force the tablets into the apertures 65 in the platform. In a fifth machine, Fig. 17 (not shown), similar to the Fig. 14 machine except that the rotating platform feeds preformed tablets instead of powder, encased tablets are made as shown in Fig. 22. In a sixth machine, Figs. 4 and 5, the feeding device comprises a rotating casing 51 having a hopper portion 54 and radial vanes 57 which mix the powder and propel it along a stationary plate 52 until it falls into a die. Passages 60 in the vanes maintain approximate uniformity in the amount contained in the apertures 58 between the vanes. Instead of the radial bed 11 of Fig. 1, an oblique bed 73 is used so that the casing 51 presents less resistance to a raised punch.