Patent GB-260362-A (GB)
Title: Method and apparatus for forming products from pulpy mass
IPC: D21J5/00
Filed: 1925-08-05
Abstract: 260,362. Buel, H. Aug. 5, 1925. Moulding pulp.- Consists in forcing pulp under a pressure of 40 lbs. per square inch or more into a mould to form a coating thereon and subsequently forcing a heated gas against the inner surface of such coating under pressure while subjecting the exterior to vacuum; the heating is preferably effected by highly heated inert gas under a pressure sufficiently high to prevent charring e.g. over 275‹ F. and 75 lbs. per square inch. Figs. 1 and 4 show an apparatus comprising a mould 1 having perforated walls 2 supporting gauze &c. 3, the mould being in two parts adapted to be opened and closed by #-members 71 furnished with pins engaging cam slots. Pulp is supplied from a tank through pipes 28, 26 and valve 29 to the mould under a pressure of 75-125 lbs. per square inch, the expressed water discharging through an outlet 6 preferably directly into a drain &c. When the requisite amount of pulp has entered the mould, the valve 29 is closed and compressed gas is introduced through a pipe 43 fitted with admission and check valves 44, 45<a>. The gas pressure may be applied intermittently to cause felting of the pulp. Heated gas is next introduced through a pipe 45 fitted with admission and check valves and vacuum is applied to the outlet 6. The gas is heated by an electric heater 48. After drying, a filling-material may be introduced through a valved pipe 53, being preferably dissolved in a volatile solvent which is removed by heat and vacuum and recovered in a condenser. Finally the article is cooled by a non-oxidizing gas and discharged by opening the mould. Fig. 8 shows an arrangement of apparatus. Pulp is contained in tanks 27, 57 connected by pipes 28, 58 to the valve 29. Each tank is fitted with stirring-apparatus 30 and is connected by a pipe 31 to a suitable supply tank, the supply being maintained by a pump 32 driven by an electromotor 33 controlled by a switch 40 actuated by a spring piston 34 under gas pressure within the tank. The mould outlets 6 are adapted to connect with a branched pipe 7 leading to a header 9 connected through a condenser 10 and scrubbers 12, 13 to a vacuum pump 8 discharging into a tank 16 from which the gas is passed through a charcoal &c. burner 19 to remove oxygen, then through a cooler 21 to a storage tank 24 connected by pipes 41, 42, 46 to the pipes 43, 45. Filling material is contained in a vessel 50 fitted with a supply pipe 51. The apparatus is operated automatically through cams &c. Layers of different classes of pulp may be deposited successively. Fig. 11 shows a modification comprising a three-part mould composed of sections 13<1> moved inwardly against the action of springs 26<1> by pistons 19<1> operated by fluid from a tank 22<1> subjected to compressed air controlled by a valve 24<1>. A top mould section 14<1> is carried by a plunger 27<1>. Pulp is supplied to the mould from a tank 1<1> through a conduit 6' fitted with valves 39<1>, 40<1>; and compressed air from a tank 41<1> associated with a heating-coil 42<1>. An example of the process, using air, is also described.