GB2275015A - Destructible hollow formers for manufacture of hollow composite articles - Google Patents

Destructible hollow formers for manufacture of hollow composite articles Download PDF

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Publication number
GB2275015A
GB2275015A GB9402377A GB9402377A GB2275015A GB 2275015 A GB2275015 A GB 2275015A GB 9402377 A GB9402377 A GB 9402377A GB 9402377 A GB9402377 A GB 9402377A GB 2275015 A GB2275015 A GB 2275015A
Authority
GB
United Kingdom
Prior art keywords
tool
former
hollow
compound
destructible
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9402377A
Other versions
GB2275015B (en
GB9402377D0 (en
Inventor
Richard Brian Tomkinson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FPT Industries Ltd
Original Assignee
FPT Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by FPT Industries Ltd filed Critical FPT Industries Ltd
Publication of GB9402377D0 publication Critical patent/GB9402377D0/en
Publication of GB2275015A publication Critical patent/GB2275015A/en
Application granted granted Critical
Publication of GB2275015B publication Critical patent/GB2275015B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C53/00Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
    • B29C53/80Component parts, details or accessories; Auxiliary operations
    • B29C53/82Cores or mandrels
    • B29C53/821Mandrels especially adapted for winding and joining
    • B29C53/822Single use mandrels, e.g. destructible, becoming part of the wound articles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/38Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/44Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
    • B29C33/448Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles destructible
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/04Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C69/00Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore
    • B29C69/02Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore of moulding techniques only
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/44Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
    • B29C33/52Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2021/00Use of unspecified rubbers as moulding material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/08Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
    • B29K2105/0809Fabrics
    • B29K2105/0845Woven fabrics

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Moulding By Coating Moulds (AREA)

Abstract

A destructible hollow former for use in the manufacture of a hollow article from composite materials is produced by rotational moulding a hot melt/cold set compound which is frangible and/or water soluble in a solid state. After lay-up and cure of the hollow article the former may be destroyed by breaking it into pieces sufficiently small for removal through an aperture in the article. Alternatively it may be destroyed by dissolution in water.

Description

Description of Invention TITLE: DESTRUCTIBLE HOLLOW FORMERS FOR MANUFACTURE OF HOLLOW COMPOSITE ARTICLES This invention relates to hollow composite articles and is more particularly concerned with production of destructible hollow formers on which composite materials are laid up and cured in manufacture of such hollow articles.
At the present time flexible fuel tanks such as may be used in aircraft and which may be self-sealing in the event of puncture, are manufactured by laying up sheets of fuel resistant rubber and layers of reinforcing fabric on a metal jig. The jig must be robust in order to withstand the pressures that have to be applied to form the materials around any section changes of a tank during curing of the rubber. After the rubber has been cured the jig must be disassembled and extracted through a convenient access hole in the tank, such as a hole for attachment of a fuel filler pipe. This is a difficult and time consuming operation particularly when small tanks are being manufactured.
A similar problem exists in manufacture of hollow articles from fibre reinforced composite materials, for example glass or carbon fibre reinforced thermosetting or thermoplastic materials, particularly when the article is small in size and has section changes. It is known to manufacture destructible formers or mandrels for use in the production of such articles from cold setting thermoplastic or eutectic salt materials.
Such materials are frangible and water soluble in their solid state so that the former may be broken into pieces or dissolved after the resin system used in the manufacture of the hollow article has set.
One known method of manufacturing a destructible former from these materials is to cast the molten material in a mould having an internal shape which corresponds with the internal shape of the hollow article that it is required to produce. The molten material in contact with the wall of the mould solidifies first and when sufficient of the material is judged to have hardened, the surplus molten material in the centre of the mould can be poured out to leave a hollow former that is removed by splitting the mould. A former made by this technique has considerable wall thickness so that it is not easily broken up for extraction from the interior of a hollow article after the article has been cured and an extensive time is required for its removal by dissolution in water.
Another method used to manufacture destructible formers is so-called "slush moulding".
A quantity of molten material is introduced into a mould which, after being closed, is sloshed about so that the molten material comes into contact with all of the internal surface area of the mould. This results in a hollow former having uneven wall thickness that may be difficult to break into small pieces. Also, being of uneven wall thickness, it does not lend itself to the provision of a uniform temperature if the materials used to produce an article by laying up on the former are required to be heat cured.
In its broadest aspect the present invention overcomes the aforementioned disadvantages by a method of manufacturing a destructible hollow former from a hot melt/cold set compound which is frangible and/or water soluble in a solid state, comprising rotationally moulding the former in a rotational moulding tool.
Preferably, the hot melt/cold set compound is introduced into the rotational moulding tool in powder form and heated in the tool to a temperature at which the powder becomes molten. However, if desired the compound may be in the form of small fragments of solid material or it may be melted and poured into a pre-heated tool.
Rotational moulding a destructible hollow former in accordance with the present invention minimises the quantity of material required to produce a former having a wall thickness dimension necessary to give the former adequate strength to withstand the pressures to which it will be subjected during production of a hollow composite article, whilst ensuring the former wall is of substantially uniform wall thickness throughout.
In another aspect the invention provides a destructible hollow former for use in manufacturing a hollow article from composite materials, the former being rotationally moulded from a hot melt/cold set compound which is frangible and water soluble in a solid state.
The hot melt/cold set compound may be a suitable thermoplastic or it may be a eutectic salt.
In a further aspect the present invention provides a method of manufacturing a hollow article from composite materials comprising the steps of: a. charging a rotational moulding tool having an internal shape corresponding with an external shape of a destructible hollow former to be produced in the tool with sufficient quantity of a hot melt/cold set water soluble compound as is required to coat internal surfaces of the tool to a desired thickness; b. fixing the tool on a rotatable member of a rotational moulding machine; c. switching on the machine to rotate the tool; d. moving the tool into a heated oven whilst continuing rotation; e. rotating the tool in the heated oven for sufficient time to permit the compound to become molten and coat all internal surfaces of the tool; f. removing the tool from the oven and continuing rotation of the tool to allow the tool to cool to a temperature at which the compound hardens; g. switching off the machine, opening the tool and removing a rotationally moulded destructible hollow former; h. laying up on the former a required combination of materials; i. curing the combination of materials on the former; j. destroying the former to obtain the hollow article.
In step j. the former may be destroyed by impacting it with a hard instrument, such as a hammer, to break it into pieces sufficiently small for removal from the finished article through a convenient aperture in the article.
Alternatively, in step j. the former may be destroyed by dissolution in water.
The compound may be introduced into the moulding tool in powder form or as small fragments and heated in the tool until it is molten.
Alternatively, the compound may be introduced into the tool in molten form in which case it is preferable to pre-heat the tool.
Any suitable combination of materials may be used to manufacture a hollow article on a former produced by rotational moulding in accordance with the present invention.
For example, in manufacture of a flexible tank for containment of fuel or other liquid, layers of sheet rubber interspersed with woven nylon fabric may be laid up on the former and the rubber cured at temperature and under pressure. As another example, layers of glass fibres or carbon fibres pre-impregnated with a desired epoxy resin system may be laid up on a destructible former and the resin may be cold cured or cured at temperature depending upon its curing requirement.
Two suitable compounds for use in the manufacture of destructible hollow formers by rotational moulding in accordance with the present invention are a hot melt/cold set water soluble compound sold under the trade name "TEMPLEMAN 4150 SYSTEM" by Templeman Industries (U.K.) Limited, Unit 10, Tower Square, St. Peters Road, Huntingdon, Cambridgeshire, England; and a hot melt/cold set water soluble compound sold under the trade name "PARAPLAST" by Mason Chemicals Limited, Carolyn House, Dingwall Road, Croydon, England.
The manufacture of a destructible hollow former by rotational moulding will now be described by way of example only and with reference to the accompanying drawing of which: Figure 1 is a perspective view of a destructible hollow former produced in a first rotational moulding test; Figure 2 is a side elevation of a destructible hollow former produced in a second rotational moulding test; and Figure 3 is a view in plan of the former shown in Figure 2.
In a first rotational moulding test aimed at producing a simple destructible hollow former 10, reference Figure 1, a rotational moulding tool (not shown) was charged with 3 kilograms of a hot melt/cold set water soluble compound in powder form, in this test the compound being that sold by Mason Chemicals Limited under the trade name "PARAPLAST 33". The rotational moulding tool was fixed to a rotatable table on a rotatable boom of a rotational moulding machine (not shown). The machine was switched on and the tool was rotated by the table at 8 r.p.m. and by the boom at 4 r.p.m. about two orthogonal axes. Whilst continuing rotation the machine was moved into a heated oven which was maintained at 1900C for 1 hour.The machine was then removed from the oven and rotation was continued for a further 45 minutes to allow the tool to cool and the PARAPLAST material to harden. The machine was then switched off and the tool allowed to cool to ambient before the tool was opened and the former removed.
In a second rotational moulding test a former 20, reference Figures 2 and 3, was produced in similar manner to that described for manufacture of the former 10 shown in Figure 1, except that in this second test a rotational moulding tool (not shown) was charged with 5.2 kilograms of fragmented cold "PARAPLAST" broken up into approximately 25 mm cubes.
The tool was then fixed to the table of the rotational moulding machine which was switched on to rotate the tool about two orthogonal axes. The machine was moved into a heated oven which was maintained at a temperature of 2500C for 1 hour whilst rotation was continued. The machine was removed from the oven and rotation was continued for a further 45 minutes to allow the tool to cool and the PARAPLAST to harden. The machine was then switched off and the tool was allowed to cool to ambient before the former was removed.
Thereafter the former 10 was used in the manufacture of a hollow composite container.
Sheets of uncured rubber and woven nylon fabric cut to requisite shapes were laid up around the former and after curing the rubber at temperature and under pressure, during which curing cycle the fabric became embedded in the rubber, the former was destroyed by impacting it with a hammer at an aperture in the container wall. The broken pieces of the former were removed from the container through the aperture. It is to be appreciated, of course, that when the configuration of an article manufactured on a former is such as not to provide an aperture of sufficient size to permit the former to be broken up, the former may be removed by dissolution in water.

Claims (4)

1. A method of manufacturing a destructible hollow former from a hot melt/cold set compound which is frangible and/or water soluble in a solid state, comprising rotationally moulding the former in a rotational moulding tool.
2. A method as claimed in Claim 1, further comprising the steps of introducing the hot melt/cold set compound into the tool in powder form and heating the tool to a temperature at which the powder becomes molten.
3. A destructible hollow former for use in manufacturing a hollow article from composite materials, the former being rotationally moulded from a hot melt/cold set compound which is frangible and water soluble in a solid state.
4. A method of manufacturing a hollow article from composite materials comprising the steps of: a. charging a rotational moulding tool having an internal shape corresponding with an external shape of a destructible hollow former to be produced in the tool with sufficient quantity of a hot melt/cold set water soluble compound as is required to coat internal surfaces of the tool to a desired thickness; b. fixing the tool on a rotatable member of a rotational moulding machine; c. switching on the machine to rotate the tool; d. moving the tool into a heated oven whilst continuing rotation; e. rotating the tool in the heated oven for sufficient time to permit the compound to become molten and coat all internal surfaces of the tool; f. removing the tool from the oven and continuing rotation of the tool to allow the tool to cool to a temperature at which the compound hardens;
GB9402377A 1993-02-10 1994-02-08 Destructible hollow formers for manufacture of hollow composite articles Expired - Fee Related GB2275015B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB939302647A GB9302647D0 (en) 1993-02-10 1993-02-10 Disposable formers for manufacture of hollow composite articles

Publications (3)

Publication Number Publication Date
GB9402377D0 GB9402377D0 (en) 1994-03-30
GB2275015A true GB2275015A (en) 1994-08-17
GB2275015B GB2275015B (en) 1996-09-04

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Family Applications (2)

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GB939302647A Pending GB9302647D0 (en) 1993-02-10 1993-02-10 Disposable formers for manufacture of hollow composite articles
GB9402377A Expired - Fee Related GB2275015B (en) 1993-02-10 1994-02-08 Destructible hollow formers for manufacture of hollow composite articles

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GB939302647A Pending GB9302647D0 (en) 1993-02-10 1993-02-10 Disposable formers for manufacture of hollow composite articles

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1010513A2 (en) * 1998-12-15 2000-06-21 United Technologies Corporation Foam mandrel for a filament wound composite casing
EP1676694A1 (en) * 2004-12-30 2006-07-05 The Goodyear Tire & Rubber Company Degradable sipe blade for tire curing molds

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021105844A1 (en) * 2021-03-10 2022-09-15 Fit Ag Process for the production of an elastically deformable molded part

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1015125A (en) * 1961-10-16 1965-12-31 Goodyear Tire & Rubber Polyurethane structure
GB1114651A (en) * 1964-08-18 1968-05-22 Technigaz Improvements in or relating to method of and machine for manufacturing tanks for the storage of products under pressure, and tanks thus obtained
US5076871A (en) * 1990-01-11 1991-12-31 The Boeing Company Method of forming composite prepreg articles utilizing heat-shrinkable braided sleeves

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1015125A (en) * 1961-10-16 1965-12-31 Goodyear Tire & Rubber Polyurethane structure
GB1114651A (en) * 1964-08-18 1968-05-22 Technigaz Improvements in or relating to method of and machine for manufacturing tanks for the storage of products under pressure, and tanks thus obtained
US5076871A (en) * 1990-01-11 1991-12-31 The Boeing Company Method of forming composite prepreg articles utilizing heat-shrinkable braided sleeves

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1010513A2 (en) * 1998-12-15 2000-06-21 United Technologies Corporation Foam mandrel for a filament wound composite casing
EP1010513A3 (en) * 1998-12-15 2001-02-28 United Technologies Corporation Foam mandrel for a filament wound composite casing
EP1676694A1 (en) * 2004-12-30 2006-07-05 The Goodyear Tire & Rubber Company Degradable sipe blade for tire curing molds
US7468153B2 (en) 2004-12-30 2008-12-23 The Goodyear Tire & Rubber Co. Degradable blading for tire curing molds

Also Published As

Publication number Publication date
GB2275015B (en) 1996-09-04
GB9302647D0 (en) 1993-03-24
GB9402377D0 (en) 1994-03-30

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20120208