Patent GB-1285457-A (GB)
Title: Method and apparatus for forming a tubular fibrous body
IPC: F16L59/02
Filed: 1969-12-05
Abstract: 1285457 Making fibrous tubes; spigot and socket joints OWENS-CORNING FIBERGLAS CORP 5 Dec 1969 [6 Dec 1968] 59601/69 Headings F2P and F2G A tube is formed by winding fibres treated with an uncured binder on to a mandrel and then curing the binder. The tube (32, Fig. 17, not shown) is preferably formed from a plurality of convolutions of resin impregnated glass-fibre mat, and has spigot (400) and socket (395) portions, compressed to a greater density than the rest of the tube. The surface of spigot (400) carries embossments (401) to provide a firm joint. A thermosetting phenolformaldehyde or polyester resin is preferred, although a thermoplastic binder may be used instead. In a preferred embodiment the mandrel 24, Fig. 1, is perforated (see Division B3) and is connected by ducts 30 and 288 to air blower 290 which produces a partial vacuum inside the mandrel thereby assisting the winding on of the resin impregnated mat 44, and by ducts 30 and 270 to hot air blower 272 which supplies hot air to the mandrel 24 to produce curing of the binder. The interior of the mandrel 24 is fitted with a series of baffles, shown in Fig. 7, to distribute the hot air substantially uniformly over the surface of the mandrel. Baffles 305 and 309 inside the dutc limit the flow of hot air during the initial curing period to prevent the fibres being blown off the mat. The resin impregnated fibre mat 44 is pulled from the cylindrically-shaped package 46 by endless belt 42 through feed rollers 50, 52 and pressed on to mandrel 24 by open mesh metal belt 125, the pressure being exerted over an arc of less than 180 degrees. The belt 125 is carried by rollers 130, 133, 158 and 154 supported in a carriage 110 mounted for movement in frame 10, the carriage being shown in its standby position in Fig. 1 and its operative position in Fig. 2. A smaller open mesh metal belt 127 applies additional pressure to one end of the mat as it is applied to the mandrel 24, thus producing a strongly compressed spigot portion (400) of the tube. The other end of the mandrel is provided with a sleeve (392, Fig. 7, not shown) so that the mat 44 pressed over sleeve (392) by belt 125 forms the greatly compressed socket portion (396) of the resin bonded fibre tube (32). The tension in belts 125 and 127 is controlled by hydraulic cylinders. The belts 125 and 127 are maintained at a constant temperature within the range 150‹ to 400‹ F. by hot air from blower 272 conveyed by duct 284 and/or by a radiant gas heater 311. After the required length of mat 44 has been delivered to the mandrel, as determined by counter (103, Fig. 3, not shown), which counts the revolutions of axle 37 which carries rollers which support endless belt 42, the movement of belt 42 and feed rollers 50 and 52 is stopped, thus tearing the fibre mat 44. This tear produces a smooth external surface on the fibre bound tube (32), and a smooth interior surface for the next tube to be produced. The tension in belts 125 and 127 is reduced whilst the resin is cured by hot air blown by blower 272 through perforations in mandrel 24. Cutters 222 are then lowered to trim the rotating tube by cutting off the end portions. The production of the ducts is automatically controlled by timers TR, limit switches LS, solenoid valves SV, and counter 103, the electrical and hydraulic circuits being given (in Figs. 14-16, not shown).