Patent GB-867008-A (GB)
Title: Improvements in or relating to pressure containers and to methods and apparatus for making same
Inventor: FISHER WILLIAM THOBY
IPC: B29C53/60
Filed: 1956-01-20
Abstract: 867,008. Making pressure-resistant vessels. BRISTOL AEROJET Ltd. April 23, 1957 [Jan. 20, 1956], No. 2077/56. Class 87(2). [Also in Group XXV] A pressure vessel having a spherical casing formed from filament bonded with thermosetting resin is made by winding on to a spherical former a multiplicity of great circle turns of filament by rotating the former simutaneously and at related speeds about the polar axis and another diametral axis and during the course of the winding operation changing the angle between the axis either continuously or stepby-step. A hollow spherical former 7 is cast from a readily fusible material, e.g. Wood's metal, and provided with aligned bores 9 into each of which fits a spigot 10 on a polar spindle fitting 11. The fittings 11 are screw threaded internally at 12 and externally at 13 and 14 to engage respectively flanged polar fittings 2 and a spacer tube 15. The winding machine is provided with externally threaded spindles 17 to engage the screw threads 12 of the spindle fittings. From Fig. 1 it is seen that the former 7 is supported by the polar spindles 11 on two arcuate arms 19 and 20, the end of arm 19 remote from the spindle 11 being supported by three rollers 21 in a crosshead 22 fixed to a shaft 23 journalled in bearings 24 and 25. Similarly the corresponding end of arm 20 is connected to a shaft 28 which runs in bearings 29 and 30. The mounting of the former thus allows for rotation about three axes passing through the centre of the former : (i) about the polar axis, i.e. spindles 11, (ii) about the axis of shafts 23, 28, the winding axis, and (iii) about an axis perpendicular to (i) and (ii) by the running of the arcuate arms 19 and 20 on the rollers 21 and 26, the polar tilt axis. As a strip 77 of filaments, composed e.g. of strands 78 of loosely twisted glass filament yarn, is wound on to the former 7, it is impregnated with a liquid thermosetting resin mixture, e.g. polyester or epoxy resin with suitable catalyst and/or accelerator. Before commencing winding, the former may be coated with a layer of impervious material such as rubber which overlaps the inwardly directed surfaces of the flanges 5 of the polar fittings 2. In practice it is found satisfactory for the ratio of the polar speed to the winding speed to be between a half and twice the ratio of the width of the strip material to half the equatorial circumference of the former. The winding first passes over the flanges 5 of the polar fittings 2 with sufficient overlap to provide the necessary strength and then the angle of polar tilt is gradually increased until the whole of the strip material to be used has been wound on to the former when the polar tilt is about 65 degrees as indicated by the dotted line in Fig. 1. When the container has been completely wound, the supply of strip material is cut off and a casing in two halves containing electrical or other heating elements is placed around the former, the assembly being heated to cure the resin. After curing, steam is passed into the former which is fused. It is at this stage that the impervious layer 6 may be applied by pouring a setting liquid such as latex into the container instead of prior to winding. Reference has been directed by the Comptroller to Specification 770,036.