GB547751A - Improvements in method and apparatus for making corrugated tubes - Google Patents

Abstract

547,751. Flexible tubes. UNITED STATES RUBBER CO. April 22, 1941, No. 5164. Convention date, May 29, 1940. [Class 99 (ii)] [Also in Group V] A stretchable circumferentially-corrugated mandrel 10 is stretched as shown in Fig. 3, a plain rubber or other tube 24 is telescoped over the mandrel, the mandrel is allowed to contract, whereby the tube is folded to form corrugations, as shown in Fig. 8, and the contracted mandrel with the (rubber) tube thereon, is put into a vulcanizing chamber. After vulcanization, the mandrel-tube assembly, mounted on the rod 11, is replaced in the position shown in Fig. 3, the rod being secured in a support 13, the assembly is stretched, and the tube is pulled off. To facilitate telescoping of the plain tube over the stretched mandrel, the (interiorly-and-exteriorlytalc-dusted raw rubber) tube 24 may first be placed within a canvas retaining tube 23, a compressed air nozzle 27 being inserted within one end of the tube 24, the other end of the tube being fitted over the mandrel (Fig: 5) and compressed air being admitted between the tube and mandrel, the tube sliding along the cushion of air thus formed ; holes in the mandrel permit air to escape. A similar procedure is adopted when removing the vulcanized tube from the mandrel. A stockinette tube may be placed on the tube 24 before it is shaped on the mandrel 10, the tube 24 being previously coated exteriorly with a rubber adhesive on which is dusted zinc stearate which renders the adhesive temporarily non-tacky ; during vulcanization the stearate melts and is absorbed by the rubber, and the. stockinette becomes permanently bonded to the rubber. In a modification, the tube 24 is coated exteriorly with rubber adhesive or zinc stearate, the stockinette tube is slipped over it, and the compound tube is collapsed on and removed from the mandrel, and vulcanized in a mould by the "partly moulded and blown" process, in which the compound tube is enclosed within a corrugated mould, and compressed air is blown into the tube to press the tube against the mould corrugations. The mandrel may be made of rubber composition, rubberized fabrics, or copper, and may be solid.