Moulding of articles
AssigneeNatural Resources (2000) Limited
InventorsAnthony HARDACRE, Alan SMITH
Life of this patent
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Abstract
A method of forming a molded article includes preparing a fiber suspension by liquidizing fibrous material in a suspending liquid using at least one high shear mixer. The fiber suspension is fed to the molding surface of a porous mold. The suspending liquid is removed via the pores of the porous mold to deposit suspended fibers on the mold surface as a molded article. Removing the suspending liquid is achieved by pressing a bladder formed of a flexible impermeable membrane against the article using pressure applied behind the membrane. The molded article is removed from the porous mold dried using microwave radiation generated using at least one magnetron. A molding apparatus is use in the method and a molded article is produced by the method.
Claims16
A method of forming a moulded article (32) comprising:
- preparing a fibre suspension (22) by liquidising fibrous material (12) in a suspending liquid (14) using at least one high shear mixer (16, 18);
- feeding the fibre suspension (22) to the moulding surface of a porous mould (26);
- removing said suspending liquid (14) via the pores (44) of said porous mould (26) to deposit suspended fibres on said mould surface as a moulded article (32), the step of removing said suspending liquid (14) comprising pressing a bladder (34) formed of a resilient flexible impermeable membrane against the article (32) using pressure (35) applied behind the membrane;
- removing the moulded article (32) from the porous mould (26);
- and
- drying the moulded article (32) using microwave radiation generated using at least one magnetron (48).
A method of forming a moulded article (32) as claimed in either one of the preceding claims, wherein the or each magnetron (48) operates at a power rating of less than 5 kW.
A method as claimed in any one of the preceding claims, wherein a plurality of magnetrons (48) arranged in an array (50) are used.
A method as claimed in any one of the preceding claims, wherein the magnetrons (48) have individually controllable power outputs.
A method as claimed in any one of the preceding claims, wherein the microwave radiation is transmitted from the magnetron(s) (48) to the moulded article (32) without use of a wave guide.
A method as claimed in any one of the preceding claims, wherein the bladder (34) is used to transport the moulded article (32) from the porous mould (26) for drying.
A method as claimed in any one of the preceding claims, wherein no hot air or infra-red radiation is used in drying the moulded article (32).
A method as claimed in any one of the preceding claims wherein no drying takes place in the porous mould (26).
A method as claimed in any one of the preceding claims, wherein the fibre suspension (22) is prepared in two stages using a first high shear mixer (16) followed by a second high shear mixer (18).
A method as claimed in any one of the preceding claims, wherein the high shear mixer(s) (16, 18) comprises rotors rotating at 1000-4000 rpm.
A method as claimed in any one of the preceding claims, wherein the porous mould (26) is formed of bonded particles and/or is formed using an additive manufacturing technique.
A moulding apparatus (10) for use in a method as claimed in any one of the preceding claims, comprising:
- a porous mould (26);
- at least one high shear mixer (16, 18) connected to supply a fibre suspension (22) to a moulding surface of the mould (26);
- and
- a bladder (34) formed of a resilient flexible impermeable membrane advanceable into the moulding surface;
- a magnetron (48) which is a source of microwave radiation.
Dependencies are inferred from the claim text.