Patent GB-1267943-A (GB)
Title: Improvements in or relating to a hollow reinforced plastics container and a process and an apparatus for making the same
Inventor: REEVES JOHN FREDERICK
IPC: E04C2/20
Filed: 1969-04-09
Abstract: 1,267,943. Moulding fibre reinforced containers. LITEWATE TRANSPORT EQUIPMENT CORP. 9 April, 1969 [29 May, 1968], No. 18159/69. Heading B5A. [Also in Divisions B3, B7, B8 and F4] A glass fibre reinforced thermally insulating plastics container, e.g. a refrigerated cargo container, truck or trailer body, is moulded within a cavity 20 defined by a female mould, the open top end whereof is closed by an upper hydraulically displaceable male mould member 34, and through an open side whereof an expansible mandrel is insertable. After waxing, and then coating the cavity defining surfaces with a liquid parting compound, successive layers of finishing glass fibre matt 48, coarser chopped strand mat 50 and woven roving 52 are laid around the base and sides of the female mould. Pre-cut insulating slabs 60 of prefoamed rigid urethane foam, or alternatively of balsa wood, which are partially encased with glass fibre reinforcing 62, are then placed vertically around the sides of the mould cavity, and then across the base which defines the roof of the container. Additional layers of woven roving 66, coarse mat 68, and finishing mat 70 are then laid around the base and sides of the cavity with sufficient excess to lap over and cover the upper surface of the mandrel, after it is inserted through the open side of the cavity 20, and across which upper surface is then laid further rigid polyurethane insulating slabs 72, completely encased by glass fibre reinforcing 73, which are then covered by overlapping the excess of the reinforcing layers 48, 50, 52. After lowering the male mould member 34 into the cavity partially towards its final position, liquid polyester resin is pumped through member 34 followed by the remainder of the resin through the base of the cavity 20, or of the mandrel, excess resin flowing upwardly past a clearance around the cavity 20 and the member 34 into a gutter 86 around the latter to form a head whereby, when the member 34 is lowered to its final position and the mandrel expanded, air bubbles may escape from the cavity 20 and be replaced by resin. The mandrel comprises exterior sheets, e.g. of -inch aluminium, provided on the interior with spaced vertical "I"- beams along the side and end walls and along the bottom and top walls with similar spaced horizontal beams 92, 94 but which are braced by vertical support columns 96 to withstand the pressures generated by the male member 34. The side walls of the mandrel are slightly expanded, e.g. by -inch, by lower and upper manually actuated jacks 98 and 100, and the end wall by a similar amount by upper and lower jacks (102, Fig. 4, not shown), acting against the posts 96, the lower jacks 98, (102) preferably being actuated before the upper jacks 94, (102) to cause an upward squeezing action on the liquid resin. In an alternative construction of similarly vertically braced mandrel (not shown), this is pneumatically or hydraulically expanded. The configuration of the glass fibre reinforcing 62 and 73 around the insulating slab 60 and 72, respectively, produces "C"- and "I"- beam reinforcements in the walls of the container, and it is stated that these may alternatively be of the nature of "hat", "Z", or "box"- beam constructions. The urethane slabs 60 and 72 extend in the direction of the major axis of their elongated cells, whereby they exert the maximum resistance to bending stress in the walls. In the manufacture of van container trailers (see Division B7) provision for the attachment of accessories and fixings is made by incorporating metallic back-up plates either along, or in a recess along, the insulation slabs, e.g. 72, in the container walls, and which may be drilled and tapped into. Metallic plates providing anchorages for the attachment of accessories may be affixed to the plastics surface by adhesive bonding and riveting, by cutting away the resin/glass fibre wall and welding to a back-up plate (see Division B3), threaded engagement with a rivet nut secured to a back-up plate, or by riveting to the back-up plate, Fig. 14 (not shown). Alternatively accessories may be attached to a threaded bolt, Fig. 9 (not shown), located in a keyhole slot cut in the resin/glass fibre wall. Electrical wiring for the trailer lights and air lines for brakes may be moulded into the container, preferably leading to break-out holes in the urethane core material, or alternatively, conduit may be moulded into the container. An "L"- beam may be moulded-in around the container opening to provide attachment for the hinges of moulded doors. A plurality of flat door panels 140 for use with the moulded containers and truck or trailer bodies may simultaneously be moulded in a mould comprising a portion 220 having hingedly attached to the base thereof a mould portion 222. Urethane foam panels wrapped with glass fibre reinforcement, in turn wrapped with surface layers of glass fibre, which may incorporate metallic back-up plates for the attachment of accessories and fixings, are located in the mould between vertical mould spacer plates 226 having projections 228 therearound which define door panel flanges 224 to which an insulating gasket is subsequently attached. Gasketing 232 is provided around the sides and bottom at the junction of the mould 220, 222. The mould portion 222 is partially closed before liquid resin is injected into the cavity at inlet 230, whereafter the portion 222 is fully closed to progressively force resin upwardly through the mould under the hinged closing action and form a head above the panels to facilitate release of entrapped air.