EP0416791A2
Expired / Lapsed
EP
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Method and apparatus for compression moulding with dielectric heating
Assignee: Motors Liquidation Co
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Filing: 1990-08-24
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Granted: —
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Expires: 2010-08-24
Abstract
Abstract A compression mould for polymer parts has telescoping mould parts (10,20) with a dielectric shear edge (16) for electrical isolation of the mould parts (10,20) and an RF source (22) is connected across the mould parts (10,20) to provide dielectric heating to the charge in the mould cavity (18). By charging the mould cavity (18) with thermoplastic or thermosetting resin, preferably re-inforced with a fibre roving, and applying an RF field to the mould parts (10,20), the charge is heated rapidly and uniformly. The mould is also heated either conventionally or by including a lossy dielectric material on the mould face for heating by the RF field. Multiple mould cavities may also be used.
Inventors
- 👤 Gerard Wladyslaw Malaczynski
- 👤 Claude Anthony Di Natale
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 02:25
CPC Classifications
B; B30; B30B; B30B15/00; B30B15/34; B29; B29C; B29C33/00; B29C33/02; B29C33/08; B29C43/00; B29C43/32; B29C43/52; B29C33/0022
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
131 words
Apparatus for compressing and curing a resin object comprising: a pair of co-operating mould parts (10,20) for imparting a shape to a body of resin material to form the object, a pair of electrodes associated with the mould parts (10,20), and means (22) for applying radio-frequency (RF) power to the electrodes to establish an electrical field between the mould parts (10,20) sufficient to dielectrically heat said body of material between the electrodes to curing temperature, characterised in that each mould part (10,20) includes a conductive portion to serve as one of said electrodes, and at least one of the mould parts (10) has a shear edge (16) formed from a dielectric material, whereby the mould parts (10,20) can come into close contact whilst maintaining electrical isolation of the conductive portions thereof.
Claim 2
Dependent Claim
131 words
Apparatus for compressing and curing a resin object comprising: a pair of co-operating mould parts (10,20) for imparting a shape to a body of resin material to form the object, a pair of electrodes associated with the mould parts (10,20), and means (22) for applying radio-frequency (RF) power to the electrodes to establish an electrical field between the mould parts (10,20) sufficient to dielectrically heat said body of material between the electrodes to curing temperature, characterised in that each mould part (10,20) includes a conductive portion to serve as one of said electrodes, and at least one of the mould parts (10) has a shear edge (16) formed from a dielectric material, whereby the mould parts (10,20) can come into close contact whilst maintaining electrical isolation of the conductive portions thereof.
Claim 3
Dependent Claim
29 words
Apparatus according to claim 1, in which the mould parts (10,20) are heated by auxiliary means (14) to prevent cooling of the object surface during curing of the object.
Claim 4
Dependent Claim
52 words
Apparatus according to claim 1, in which the mould parts (10,20) comprise male and female mould parts, each having steel bodies and shaped to co-operatively form a cavity (18) for moulding said object, the female mould part (10) having said shear edge (16) in telescoping relation to the male mould part (20).
Claim 5
Dependent Claim
40 words
Apparatus according to any one of claims 1 to 3, in which the dielectric material of the shear edge (16) is a lossy material subject to heating by the electrical field to impart heat to the edges of the object.
Claim 6
Dependent Claim
48 words
Apparatus according to claim 3, in which the cavity-forming surfaces of the male and female parts (10,20) have respective layers (30,32) of lossy dielectric material adjacent the object which are subject to heating by the electrical field to maintain a desired temperature at the object surface during moulding.
Claim 7
Dependent Claim
90 words
Apparatus according to claim 1 or 2, in which the mould parts (10,20) define a shape of non-uniform thickness, and at least one of the mould parts has a face portion adjacent the cavity comprising a dielectric material having substantially the same dielectric constant as the material of the object and is shaped to compensate for object thickness variations so that all electrical field paths include substantially equal thicknesses of dielectric materials and all parts of the object are subject to the same degree of heating by the electrical field.
Claim 8
Dependent Claim
171 words
Apparatus according to claim 1, for simultaneously compressing and curing a plurality of polymer composite parts, said apparatus comprising: a female mould part (40) having two opposed faces (46) and a plurality of cavities (48) arranged side by side on each face (46), each cavity (48) being edged by electrically-insulating shear edges (50) and being adapted to receive material to be moulded; two male mould parts (54) on opposite sides of the female mould (40), each of which is registered with one of said faces (46) and having a plurality of cores (56), each of which slides between adjacent shear edges (50) into a respective cavity (48) to compress said material within the cavity (48), and means for coupling a source (60) of radio frequency energy to the mould parts (40,54) with one polarity on the female mould part (40) and the other polarity on the male mould parts (54) so that said electric field is established between the female mould part (40) and each of the male mould parts (54).
Claim 9
Dependent Claim
95 words
A method of compression-moulding a polymer or polymer composite material in a mould according to claim 1, characterised in that the method comprises the steps of: compressing a charge of polymer material in a mould cavity (18) by telescopically moving mould parts (10,20) together under pressure, dielectrically heating the charge by applying a radio-frequency voltage across the mould parts (10,20) whilst maintaining the mould parts (10,20) electrically isolated from one another to establish a radio-frequency field through the charge, and maintaining the charge under pressure at least until curing of the polymer is partially completed.
Claim 10
Dependent Claim
68 words
A method of compression-moulding a polymer or polymer composite material in a mould according to claim 8, in which the polymer material comprises a thermoplastics coating on a fibre roving (52), and the step of maintaining the charge under pressure comprises applying the pressure until the thermoplastics material is fused to consolidate the charge and the thermoplastics material is then allowed to cool and at least partially solidify.
Claim 11
Dependent Claim
57 words
A method of compression-moulding a polymer or polymer composite material in a mould according to claim 8, in which the polymer material comprises a thermosetting material re-inforced by fibre roving (520, and the step of maintaining the charge under pressure comprises applying the pressure until the thermosetting material is at least partially cross-linked to consolidate the charge.
References Cited (Backward Citations)
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