Patent GB-420970-A (GB)
Title: Improvements in the forming of thick paper articles such as barrels, tubs, plates and the like
IPC: D21J5/00
Filed: 1933-05-05
Abstract: 420,970. Moulding pulp. WILSON, R. P., 28, Grosvenor Place, London. May 5, 1933, No. 13084. [Class 87 (ii)] Articles, such as barrels, tubs or plates, are moulded from paper pulp by sucking a layer of pulp from stuff water onto a sieve and couching, the couching being effected by a flexible body to which the formed layer of material is transferred and by which the layer is removed from the sieve. A number of layers are successively formed on the sieve by suction, each layer being couched onto the layers previously formed and transferred onto the flexible body, the layers being finally further united by pressing. Apparatus for carrying out the process comprises outer and inner forms a, b, Fig. 1, the outer form being provided with a spaced inner wall c of wire gauze, felt or the like, and the inner form having a waved, corrugated or grooved surface and being surrounded by a water and air tight bag h which is flexible but not elastic, the bag being formed for example of rubber with a canvas insertion and covered on the outside with paper maker's felt. The space d between the walls of the outer form is connected to suction through pipes e, f and a valve g, an air pipe f controlled by a valve f<2> opening into the pipe f. The inner form is carried by a piston i working in a cylinder k provided at the upper part with an annular passage k<1> connected through a pipe m and valve m<1> with a supply of stuff water. The cylinder k and the space between the bag hand the form b are connected to an air or low pressure water supply through pipes k<2> and h<3> respectively, to which pipes high pressure water may be admitted through a pipe h<5> and a non- return valve h<7>. The valves k<3>, h<4> on the pipes k<2>, h<3> are connected to a common outlet k<33> controlled by a valve k<44>, the outlet k<33> being connected through a non-return valve h<33> to a constant-head tank h<44>. The outer form a is raised by a screw, winch &c., or by hydraulic means comprising for example rams n<1>, n<2>, Fig. 8, which act upon a saddle p<2> carrying an eye p<1> which engages automatically with a hook on the frame when the form is in the raised position. The form a is bolted to a member q through which pass bolts q<2> suspended from the saddle p<2> and provided with lifting plates q<3>. The form a is secured in the lowest position by locking members p<3>, which on the lifting of the saddle p<2>, are disengaged by the plates q<3> before the plates engage beneath and lift the member q. In operation, the stuff water admission valve m<1> and the suction valve g are opened and a layer of pulp is formed on the sieve c. Water at 4-5 atmospheres pressure is then admitted first through the pipe k<2> to raise the piston k, thereby cutting off the admission of stuff water through the passage k<1>, and then through the pipe h<3> to inflate the bag h. The suction valve g is next closed, air is admitted through the valve f<2>, the water exhausted from the bag, which deflates taking the layer of pulp with it, and the valve h<4> is opened so that the piston falls. After closing the air valve f<2> and reopening the suction valve g, the series of operations is repeated, the successive layers of pulp formed being in turn transferred to the layers already upon the bag. When the material is of sufficient thickness, the piston is raised and the bag inflated by low pressure water, after which the valves k<3> and h<4> are closed and high pressure water is admitted through the pipe h<5> to consolidate the layers. The valves h<6>, g and k<44> are then closed and the valves k<3> and h<4> opened to the common exhaust pipe k<33>, whereby the cylinder and bag are exhausted to the tank h<44>, the pressure in which is sufficient to maintain the piston raised and the bag inflated. Finally, the air inlet valve f<2> is opened to release the article from the sieve, the outer form is raised, the bag deflated and the piston allowed to fall, whereupon the article is removed. The various valves may be operated in sequence either by hand, by cams, or automatically, either mechanically, pneumatically, or electrically.