GB836406A - Improvements relating to flexible tubing - Google Patents

Abstract

836,406. Corrugated flexible tubing. HOOVER Ltd. Jan. 19, 1956 [Jan, 31, 1955], No. 1912/56. Class 99(2). In a flexible extensible corrugated hose particularly for a suction cleaner the resilient helical reinforcing coil is bonded to the tube wall of thin elastomeric material over a part of the length of the hose. The hose is generally similar to those described in Specifications 784,060 and 800,371 and may be manufactured in a generally similar manner. In the Figures the reinforcing coil 11 is bonded to the hose 10 of thermoplastic elastomeric material such as polyvinyl chloride over the end portions B (one end only shown) but is not bonded to it over the major part A of the hose length. The coil 11 is of spring wire 12 sheathed or coated in a covering of thermoplastic elastomeric material 13 preferably the same material as the hose 10. The coil 11 is prestressed so as to tend to close up when free to do so. The mandrel on which the stretched coil is placed may be inflated to clamp the coil in position with the turns distributed either uniformly or non uniformly. Prior to positioning of the radially stretched thermoplastic tube 10 over the coil appropriate areas of the coil are coated with a solvent for the material of the sheath and tube. The solvent or a cement for the thermoplastic material may be sparingly applied to the reinforcing element so as to be confined to the areas to be bonded. Alternatively the hose carcase may be retained in its stretched condition until the solvent or cement has had an opportunity to evaporate or dry. Specification 836,407 also is referred to.