Patent GB-761212-A (GB)
Title: Reinforced flexible conduits and method for manufacturing same
IPC: B29D23/18
Filed: 1954-11-25
Abstract: 761,212. Flexible tubes. DAYTON RUBBER CO. Nov. 25, 1954 [Dec. 14, 1953], No. 34146/54. Class 99(2) In a hose including a helical reinforcing member 44 which has at least the surface thereof made of flexible material such as natural rubber, synthetic rubber-like compositions, or plastic material, and which is surrounded by a tube 41 of the same material, the tube is corrugated between the convolutions of the member and together with the latter provides a smooth cvlindrical inner hose surface composed of alternating surface sections of the tube and the member. The preferred materials are natural rubber, the various synthetic rubber-like compositions such as polychloroprenes known as neoprene, the butadiene-styrene copolymers known as Buna-S or GR-S (Registered Trade Marks), the butadiene-acrylic nitrile copolymers referred to a Buna-N or GR-A, the various polysulphides known as Thiokol (Registered Trade Mark), Butyl rubber, the various mouldable thermoplastic materials such as vinyl copolymers, the cellulose compounds, and polyethylene, or a mixture or combination of any of these materials. As shown in Fig. 7, the reinforcing member 44 comprises a helically wound wire 45 uniformly coated with a plastic material 46 having a flat surface 48; alternatively, the member consists of plastic material, or the plastic coating of the wire is extruded and triangular in cross-section, Fig. 8 (not shown), to present a flat surface at the interior surface of the hose. In constructing the hose a reinforcing member 10, Figs. 2 and 3 is placed on a perforated, hollow mandrel 13. closed at each end by a plug 20, and, if required, held in the desired position by friction tape, end reinforcements 16, 17 of rubberized fabric, which may be incorporated in the hose, being placed at each end of the mandrel before or after positioning the member. A tube 19 of plastic material having an internal diameter less than the external diameter of the mandrel is positioned over the member 10 to extend beyond the ends of the member and cover all the perforations 18 in the mandrel, the elastic nature of the tube causing the tube to draw inwardly and to firmly grasp and coalesce with the member. The ends of the tube are bound with friction tape as shown at 21 and 21a to more effectively, seal the interior of the mandrel from the surrounding atmosphere, and an adhesive may be applied between the member and tube; alternatively, the mandrel is provided at one end with a valve and the interior of the mandrel is subjected to a vacuum so that the tube 19 is forced by the surrounding atmosphere inwardly and around the member 10 and against the mandrel to form corrugations in the wall of the hose. The corrugations can be formed by winding a cord or cable about the tube and between the convolutions of the member 10. The completed hose assembly is placed in a curing chamber 33, Fig. 5, provided with inlet or outlet means 34, or both, through which heated air or steam under the desired pressure conditions may be introduced into the chamber. The mandrel is supported on blocks 35, 36. When the hose is made according to method described with reference to Fig. 3 the pressure in the chamber is such as to force the tube 19 inwardly and around the convolutions of the member 10 to obtain a corrugated exterior surface. The interior of the mandrel may be subjected to a vacuum while in the chamber. In an alternative method of curing the hose, each end of the wire helix is connected to a source of electric current the heating effect of which causes curing of and coalescence between the member 10 and tube 19. In order to enhance the flexibility of the hose, the hose may be axially compressed after the initial corrugating step and partial curing.