Patent GB-695665-A (GB)
Title: Improvements relating to the formation and filling of plastic capsules
IPC: G08B5/36
Filed: 1951-05-17
Abstract: 695,665. Moulding capsules: gelatine compositions. AMERICAN CYANAMID CO. May 17, 1951 [May 26, 1950]. No. 11542/51. Classes 70 and 87 (ii). A capsule making machine in which cavities are formed by suction in a gelatine strip 21, Fig. 4, filled with material, sealed by a gelatine strip 78, Fig. 5, and the capsules cut out simultaneously with the sealing operation, has a nozzle 53 for feeding liquid to the capsule and a roller 58 having cavities 57 for feeding a measured quantity of powder 52 to the capsule. The liquid or both the liquid and the powder feeds may be disconnected. The strip 21. Fig. 1, is fed over an oiling roller 22 which gives the outer surface of the strip a coating of a mineral oil which may be thinned with a solvent such as ligroin. The inner surface is given a protective coating of a gum or shellac in a solvent such as chloroform, ether, carbon tetrachloride, petroleum and ether, or ligroin by a roller 26. The strip is then drawn into the cavities in a roller 29, and the liquid is fed by a gear pump 55 which may be of the kind described in U.S.A. Specification 1,785,386 into the cavities. The pump is driven through a variable drive and a clutch from the machine drive. Powder in a hopper 59 is agitated by members 60 and a stream of gas which is supplied through a pipe 61. Suction is applied to the cavities 57 through filters 62, Fig. 4, to draw the powder into the cavities. A doctor at the front of the hopper smooths the powder. The hopper is provided with felt and nylon fabric seals at its roller engaging edges. When the powder charge reaches D, compressed air is supplied to the cavity 57 and the powder charge is blown into the capsule cavity. The cavities 57 are cleaned by compressed air and the particles are removed by suction through a shield 68 (see Figs. 8 to 10, not shown). As the roller 29 rotates, the filled capsule cavities engage the gelatine strip 78 which may be held on a sealing roller 70 by suction. This roller is pressed against the roller 29 by a spring 73 and is heated by thermostatically controlled electric elements 75. An indicator is provided to show when the roller is being heated. The temperature of the roller 70 is generally higher than that of the rest of the machine. The roller may have depressions to provide room for relief of the capsule contents during sealing. The strip 78 may be coated similarly to the strip 21. The cutting out rim around the capsule cavities seals the strips together and cuts out the now completed capsule. During sealing, the suction is released to prevent strains in the strips. After sealing the suction is again applied and the residual strips are drawn off by rollers 80, 81, Fig. 1. When the now completed capsule reaches a shield 82, the suction is released and the capsule ejected by a plug 33, Fig. 4. A rotating fabric stripper 83 aids in the removal of the capsule. The capsules are carried off by a pneumatic conveyer 85 (see Fig. 16, not shown) which may discharge the capsules in either of two directions. The air helps to tumble, cool and dry the capsules and thus prevent them from sticking to each other. The capsules may be discharged into a drying pan. The application of suction and compressed air to the rollers 29, 58 is controlled by valve plates 38, 64 which may be adjusted by screws 51, 52 and 65. In a modification Fig. 13 (not shown), the powder roller 58 is smaller than the roller 29 and the liquid may be fed into the cavities before or after the powder or both. The cavities may be tapered to facilitate the discharge of the capsules. The gelatine strip may be pre-stretched to alter the final shape of the capsules which may be elliptical, round or oval (see Figs. 7, 14 and 15, not shown). A transparent finger guard may be placed near the bite between the rollers 29, 58 and 29, 70. The capsule may be completely filled or the sealing area may be surrounded with an inert gas, if the filling is sensitive to air. The gelatine strip may be made from gelatine plasticized with polyethylene oxide with or without glycerine. In an example 48 parts by weight of gelatine, 18 parts of glycerine and 36 parts of water are chilled and then mixed together.