GB1142006A - Method of and apparatus for making an elongated tubular object - Google Patents

Abstract

1,142,006. Moulding tubular objects. FABRIEK EN HANDELSBUREAU "NEDERLAND". 13 May, 1966 [26 May, 1965], No. 22373/65. Heading B5A. In the moulding of preferably non-circular section e.g. hexagonal, octagonal or elliptical, tubular objects from glass fibre reinforced polyester resin e.g. road lighting columns, sign posts, signal posts or beacons, the glass fibre reinforcement 19 is applied as one or more mattings or layers adjacent the interior surface of a vertical mould 11 which is provided with external steam or electrical heating coils 20 and to the lower end 11a of which is connected an inflatable tube 12 e.g. of rubber, and into which lower end e.g. via an inlet 18, a synthetic resin is admitted whereby, with a pressure difference created between the inflatable tube 12 and the interior of the mould 11, the inflatable tube 12 is caused to progressively inflate into the interior of the mould 11 by feeding the pinched end thereof through rolls 25 into the mould, to press the resin upwardly into the reinforcement. The pressure difference is created by a vacuum connection 15 into the upper end of the mould 11 or, alternatively or in addition thereto, pressure may be applied to the interior of the inflatable tube 12 inside the mould, via a casing 16 enclosing the lower part of the mould and the rolls 25. The resin may be admitted to the interior of the mould before, during or after the pressure difference is applied, either by means of the vacuum in the mould, and/or it may be pumped in. Preferably the pressure difference is maintained until the resin has hardened or cured, which may be effected by the heating coils 20. Preferably a thin tubular protective sleeve 21 e.g. of p.v.c., is inserted between the inflatable tube 12 and the mould and is connected at its other end on a tube 22 to the vacuum connection 15; a hole 23 in the tube 22 balances the pressure on both sides of the sleeve 21 and connects the interior of the mould to the vacuum connection 15. The sleeve may be drawn through and secured in the mould 11 after the reinforcement has been placed in the mould or, alternatively, the reinforcement may be applied about the sleeve 21 supported on a temporary mandrel which is withdrawn after the sleeve 21 has been secured at its upper end to the tube 22. Longitudinally extending metal reinforcing bars 24 may be located in the mould e.g. between two layers of glass fibre. The mould 11 is preferably provided with an overflow 26 at its uppermost end to receive excess resin. The mould may be in a single-piece, or may be a multi-piece mould whereby local bulges or side branches are moulded.