Foam plastics manufacturing method and machine
AssigneeCannon Viking Limited
InventorAnthony Charles Murray Griffiths
Life of this patent
Estimating the term…
Abstract
Production of foamed materials in a horizontal machine, and said machine itself, reactants being fed to a conveyor at one end of the machine and foam produced being removed at the other end, wherein the foam is generated in an expansion chamber defined at its inlet by a closed reactant feed zone, at its outlet by a body of foam already expanded or partly expanded, and laterally and vertically by travelling webs, the webs giving a diverging cross section to the chamber.
Claims24
Production of foamed slabstock in a horizontal machine, reactants being fed through a reactant feed zone to a conveyor at one end of the machine and foam produced being removed at the other end, wherein in order to support and constrain the rise profile of a body of expanding foam while in the fluid state:
- the reactant feed zone is closed, with no exposure of reactants to the atmosphere,
- the foam is generated in an expansion chamber closed at its inlet by the reactant feed zone, at its outlet by a body of foam already expanded or partly-expanded, at top sides and bottom by travelling webs,
- the chamber has a cross-section area that progressively increases in the direction of production,
- the base of the expansion chamber is not inclined forwards or is so inclined by no more than 10 degrees to the horizontal.
Production of foam according to any preceding claim, wherein at least an initial section of the conveyor and thus at least part of the base of the expansion chamber slopes backwards in the production direction at up to 30° to the horizontal, optionally at up to 15° to the horizontal, the foam leaving this section having reached at most 60%, optionally no more than 20 to 30%, of its full-rise volume, whereby the body of foam produced does not have to change direction after it has ceased to be fluid.
Production of foam according to any preceding claim, wherein the feed zone is the exit from a trough sealed against the webs and itself fed with reactants, expansion of the foam optionally starting in the trough.
Production of foam according to any preceding claim, wherein the reactants are initially in the form of a froth produced by release of pressure on a dissolved gas.
Production of foam according to any preceding claim, wherein movable sidewalls allow the cross-machine width of the expansion chamber and hence the block width produced to be varied.
Production of foam according to any preceding claim, wherein the webs are guided to a circular cross section while the foam is still fluid, to give round block for peeling.
Production of foam according to any preceding claim, wherein the top face of the expanding foam is fully constrained centrally but only by a web at the sides, whereby the foam can displace the web to rise at the sides above the general plane of the top face, obviating the formation of rounded block shoulders and minimising trimming waste in forming square-cornered block.
Production of foam according to any preceding claim, wherein a top web is retained on the block produced but is lifted temporarily at or around full rise to allow outgassing.
Production of foam according to any preceding claim, wherein the foam machine is in an enclosure wherein the pressure can be maintained at a value above or below atmospheric pressure to influence the final foam density, the enclosure being provided with appropriate air lock to enable removal of foam blocks to atmosphere without significantly influencing the pressure inside the enclosure.
Production of foam according to any preceding claim, wherein the hot foam blocks produced are conveyed through a forced-cooling station where air is drawn though the foam blocks to cool them.
A horizontal machine for the production of foamed materials, wherein in use reactants are fed through a reactant feed zone to a conveyor at one end of the machine and foam produced is removed at the other end, and in order to support and constrain the rise profile of a body of expanding foam while in the fluid state:
- the reactant feed zone is closed, with no exposure of reactants to the atmosphere,
- the foam is generated in an expansion chamber closed at its inlet by the reactant feed zone, at its outlet by a body of foam already expanded or partly-expanded, at top sides and bottom by travelling webs,
- the chamber has a cross-section area that progressively increases in the direction of production,
- the base of the expansion chamber is not inclined forwards or is so inclined by no more than 10 degrees, to the horizontal.
18 Machine according any one of claims 13 onwards, having means to feed reactants initially in the form of a froth produced by release of pressure on a dissolved gas.
Dependencies are inferred from the claim text.