Patent GB-556608-A (GB)
Title: Improvements in and relating to the production of seamless hollow bodies of felted fibrous material
IPC: D21J3/00
Filed: 1942-03-06
Abstract: 556,608. Moulding hollow articles from pulp suspensions. PAPERCRETE, Ltd., and NEWBOULD, M. G. R. March 6, 1942, No. 2971. [Class 87 (ii)] Pulp is deposited, preferably by suction, against the outer surface of a n-shaped foraminous core 8a, compressed by contraction of a flexible, non-foraminous #-shaped outer mould or sleeve 21a, and expanded by compressed air to free it from the core ; the sleeve is then lifted, together with the pulp body, out of the pulp chamber 1 to a drying or other station where the body is freed from the sleeve. The core comprises bars 6 and annular members 7 covered with wire gauze 8 having a perforated plate reinforcement (not shown). To reduce the free space within the core, an inner annular vessel 4 is disposed therein. The sleeve comprises rubber layers 19, 19a which cover steel slots 21 bearing pins 30 which are received loosely in slots 29 in the inner ends of levers 42 fulcrummed at 23 on a casing 12 which surrounds the sleeve. The outer ends of the levers are connected to a ring 25 rotatably mounted on the casing and connected to rams 26 operating in cylinders 27 connected with a reservoir (not shown) through a pipe 28 having a valve 28a. Operation.-(1) The sleeve, with its connections, being raised, pulp suspension is introduced through pipe 2 to fill chamber 1 to a predetermined height, pipe 10 being kept closed. Water separates from the pulp, passes through the core 8a, and fills vessel 4, which thereafter functions as a solid body. (2) Pipe 10 is opened, water is sucked away, and suspension is supplied until the desired thickness has been built up on the gauze. Excess suspension escapes through pipe 11. (3) The supply is stopped, residual water is sucked away, and air is sucked through the accreted pulp. (4) The sleeve is lowered into the position shown, and locked by means of toggle links 33, blocks 35 and recesses 36. (5) Air under pressure is introduced through pipe 16a to the space 20 between casing 12 and sleeve 21a, whereby the sleeve contracts to an extent corresponding with the lost motion between pins 30 and slots 29. The levers 22, and hence the ring 25, thus rotate clockwise and the rams 26 move to the position shown in Fig. 2b, whereby the cylinders 27 fill with water. (The valves 28a are open during this step.) (6) The valves 28a are closed. (7) The air pressure in space 20 is released. (8) Air under pressure is introduced into the core through pipe 31, whereby the hollow pulp body and the sleeve are expanded to the extent permitted by the above-mentioned lost motion. The body is thus separated from the core. At the same time, suction is applied via pipe 16a to the space 20 and via pipe 16 through a gauze layer 15b covering the top of the sleeve. (9) The casing 12, sleeve 21a and hollow pulp body are lifted by a crane connected to a rod 32, and the body is placed on a drying frame. (10) The valve 28a is opened and, suction being applied to the space 20, the body is detached from the sleeve. The core is washed by water introduced through pipe 37 to distributer 38. Porosity-reducing or waterproofing materials may be added to the pulp suspension.