GB691529A - An improved method for the manufacture of moulded articles of fibrous aqueous pulp - Google Patents

Abstract

691,529. Moulding hollow articles of fibrous material. MULLER, K. June 17, 1949, No. 16173/49. Class 87 (ii). A hollow fibrous moulded article of cylindrical prismatic or slightly conical shape, which has been deposited from fibrous aqueous pulp on a moulding sieve with rapid removal of water by the use of pressure, is subjected, on or off the moulding sieve, to a preliminary drying which reduces the water content to 30-70 per cent. by weight. It is then removed from the e moulding sieve, if this has not been done, and 'compressed to one half or less of its original thickness and simultaneously subjected to final drying, this simultaneous action being effected by causing the article to be gripped or squeezed in a heated pressing device, the gripping or squeezing progressing along the tubular part of the article until finally substantially the whole of the tubular part is under compression. The simultaneous compression and heating may be effected by using the device shown, which comprises a die a, on which the preliminarily-dried article d is placed, and a hollow plunger b which descends to compress the article, gradual compression being effected by the conical edge c on the plunger. The die and plunger are heated by bands e, f. Steam escapes through passages g in the die. Similar passages may be provided in the plunger b. A sharp edge h on the die co-operates with the edge c to trim the edge of the article. The heating may be such that the drying progress from one side of the article to the other, e.g. one of the two pressing tools is not heated or only slightly heated. The edge e may be separately heated. The conical edge c may be not on the plunger but on the die. The deposition on the moulding sieve may be effected under super-atmospheric pressure, the pulp being admitted to the sive from a closed supply container or from a pump; when a pump is used its piston may be formed as a moulding stamp which presses and moulds simultaneously. Alternatively, the deposition may be effected by pressing the pulp on to the sieve by means of a moulding sieve. The preliminary drying may be effected by hot air applied to the article either before or after it has been removed from the sieve. Reference has been directed by the Comptroller to Specification 671,692.