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GB2095606A - Forming a reinforced plastic sheet using a flexible membrane as carrier - Google Patents

Forming a reinforced plastic sheet using a flexible membrane as carrier Download PDF

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Publication number
GB2095606A
GB2095606A GB8109794A GB8109794A GB2095606A GB 2095606 A GB2095606 A GB 2095606A GB 8109794 A GB8109794 A GB 8109794A GB 8109794 A GB8109794 A GB 8109794A GB 2095606 A GB2095606 A GB 2095606A
Authority
GB
United Kingdom
Prior art keywords
membrane
mixture
shaped support
figures
reinforced plastics
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
GB8109794A
Other versions
GB2095606B (en
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.)
Hepworth Plastics Ltd
Original Assignee
Hepworth Plastics 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 Hepworth Plastics Ltd filed Critical Hepworth Plastics Ltd
Priority to GB8109794A priority Critical patent/GB2095606B/en
Publication of GB2095606A publication Critical patent/GB2095606A/en
Application granted granted Critical
Publication of GB2095606B publication Critical patent/GB2095606B/en
Expired legal-status Critical Current

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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
    • B29C70/00Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28Shaping operations therefor
    • B29C70/40Shaping or impregnating by compression not applied
    • B29C70/42Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/44Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
    • 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
    • B29C41/08Coating a former, core or other substrate by spraying or fluidisation, e.g. spraying powder
    • 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
    • B29C70/00Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06Fibrous reinforcements only
    • B29C70/08Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
    • 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
    • B29C43/00Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/10Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
    • B29C43/12Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using bags surrounding the moulding material or using membranes contacting the moulding material

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Moulding By Coating Moulds (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Abstract

A reinforced plastics article is manufactured by applying a curable reinforced plastics mixture 12 on to a flexible membrane 11, then deforming the membrane 11 to urge the mixture 12 against a shaped support 13, and allowing or causing the mixture to cure. By applying the mixture, (e.g. by spraying) to the membrane, instead of directly to the support, the mixture can be applied while the membrane has a simple, easily sprayable shape, it being the subsequent deformation of the membrane towards the support which causes the mixture to be compacted and to conform to the final desired shape. <IMAGE>

Description

the concavity of the membrane shown in Figures 2 and 3 is less than that required to accommodate the shaped support, but if the membrane was deformed fully to the final shape, it would be more difficult to spray.
The mixture is illustrated in Figure 3 by reference numeral 12.
The next stage is to remove air from between the membrane and the housing to deform the membrane, and the mixture applied thereto, into the shape shown in Figure 4. In this position the concavity is deeper than that required to accommodate the shaped article, so that the shaped article can readily be lowered into the housing as shown in Figure 5.
In this particular embodiment the shaped article comprises a moulded plastics skin 13. The free edge 15 of the plastics skin is clamped to the rim 1 6 of the housing 10 in an airtight manner but the apparatus has means (not shown) for exhausting air from the space between the skin 13 and the membrane 11.
In the next stage, shown in Figure 6, the space between the membrane 1 1 and the housing 10 is connected to atmospheric or higher pressure and air is removed from the space between the membrane 1 1 and the skin 13. This causes the membrane to be sucked tightly against the underside of the skin, compacting the plastics mixture against the underside of the skin. The plastics mixture is then left to cure at least partially under the conditions shown in Figure 6.
After curing has taken place, the clamps are removed, the space between the membrane 1 1 and the skin 13 is opened to atmosphere, and air is removed from the space between the housing 10 and the membrane 1 This pulls the membrane away from the cured plastics mixture, leaving the plastics mixture adhering to the underside of the skin as shown in Figure 7.
The completed bath is then removed from the housing as shown in Figure 8, and the membrane is then returned to the position shown in Figure 1 ready for the manufacture of a further article.
It will be appreciated that the apparatus can be used to manufacture reinforced plastics articles other than bathtubs, and furthermore the same apparatus can be used to produce a variety of different reinforced shapes, since the precise shape is dependent upon the shape of the plastics skin or other article which is fitted into the housing. Thus, for example, the apparatus could be used to produce several different designs of reinforced bathtub, having the same general overall dimensions.
When manufacturing reinforced plastics articles other than bathtubs, some other body or component may have the mixture compacted against it, instead of the moulded plastics skin 1 3.
With such an arrangement the method will initially be exactly as shown in Figures 1 to 4, and subsequent steps will be as shown in Figures 9 to 12. Figures 9 to 12 correspond exactly to Figures 5 to 8, except that a male mould 17 is used instead of the plastics skin 13.
Turning now to Figures 13 to 19, these show how the invention may be utilised to apply a reinforced plastics mixture to a generally concave or female surface.
The apparatus shown in Figure 13 comprises a base 18 and an air impermeable membrane 19 clamped thereto around the periphery of the base by a rim 20. The apparatus has means not shown to apply air to, and remove air from, the space between the base 18 and the membrane 19.
The first step in the method is to apply a pressure differential to deform the membrane into the position shown in Figure 14. In this position the membrane has been deformed into a simple shape which can easily be sprayed but has not been deformed to a sufficient height to completely fill the shaped support which is to be applied later.
The next stage is to spray on the mixture 21, as shown in Figure 15. The female shaped support 22 is then placed in position as shown in Figure 16, and is clamped to the base in an airtight manner, although there is means not shown to apply air to and remove air from the space between the mould 22 and the membrane 19.
As shown in Figure 17, air is then removed from the space between the mould 22 and the membrane 19, the pressure between the membrane 19 and the base 18 being atmospheric or higher. Thus the membrane compacts the mixture against the shaped support 22 and the mixture is allowed at least partially to cure under these conditions.
As shown in Figure 18, the membrane is then returned to its flat condition, pulling it away from the at least partially cured mixture.
The apparatus can then be separated as shown in Figure 19 and the at least partially cured mixture 21 can be removed from the shaped support 22.
With the method described with reference to Figures 13 to 19, the shaped support 22 comprises a female mould which can be repeatedly re-used. However it is also possible that the shapedrsupport 22 may comprise a component of the finished article, which remains bonded to the mixture 21, in the same way that the plastics skin 13 becomes bonded to the mixture 12 in the earlier embodiment.
The invention is not restricted to the details of the foregoing embodiments. For example, the plastics mixture may be applied to the membrane when it is in the flat condition if the shaped support does not have any pronounced concavities or convexities and the mixture is not therefore going to have to undergo a substantial change in area after application.
The mixture may be applied by means other than spraying.
Although the membrane has been deformed in the foregoing embodiments by means of differences in air pressure, it is also possible to deform the membrane by means of liquids, and water pressure may for example be used where it is desired to have close control over the temperature of the mixture. Water at a controlled SPECIFICATION Reinforced plastics articles and methods and apparatus for manufacturing them The invention relates to reinforced plastics articles and to methods and apparatus for manufacturing them.
It is known to manufacture a reinforced plastics article by spraying a mixture of curable liquid plastics material and reinforcing fibre on to a shaped support and compacting the mixture e.g.
by hand rolling. The support may be a mould which is subsequently removed after curing of the plastics material, or it may be a plastics moulding or other component which forms part of the finished article, reinforced by the plastics material sprayed on to it.
It is also known to compact the plastics material against the mould or plastics moulding by means of a membrane urged against the plastics material by vacuum and/or pressure.
It is however difficult to spray liquid plastics material and reinforcing fibre efficiently on to intricately shaped articles or articles having pronounced concave or convex regions. It is therefore difficult to automate the spraying process and the mixture may have to be applied by hand. It is even more difficult to automate the compaction process.
We have now discovered a method which enables reinforced plastics material to be applied to and compacted against a wide variety of desired shapes in a simple and easily automated manner.
Accordingly the invention provides a method of manufacturing a reinforced plastics article comprising applying a curable reinforced plastics mixture on to a flexible membrane, then deforming the membrane to urge the mixture against a shaped support, and allowing or causing the mixture to cure.
By applying the mixture (e.g. by spraying) to the membrane instead of to the shaped support, the mixture can be applied while the membrane has a simple, easily sprayable shape, and it is the subsequent deformation of the membrane towards the shaped support which causes the mixture to conform to the desired shape.
The mixture may be applied when the membrane is in a flat condition, but it is preferred that the membrane is initially deformed to a shape which approaches that of the shaped support, thus reducing the extent to which the surface area of the mixture has to change after application.
When the shaped support is of a generally convex or male configuration, the membrane may be initially deformed, e.g. by means of a pressure differential, into a concave shape shallower than that necessary to accommodate the shaped support, and thus easier to spray, then be further deformed, after the mixture has been applied, to a depth greater than that required to accommodate the shaped support, the shaped support then being inserted into the concavity and the membrane being deformed in the opposite direction to urge the mixture against the shaped support.
When the shaped support is of a generally concave or female configuration, the membrane may initially be deformed into a convex shape of insufficient height to completely fill the shaped support, the mixture is applied while the membrane is in this condition, the shaped support is then placed over the membrane, and the membrane is further deformed in the same direction to urge the material against the shaped support.
The invention includes apparatus for carrying out the method according to the invention, the apparatus comprising a flexible membrane, means to deform the membrane, and means to apply a curable reinforced plastics mixture to the membrane.
The invention includes a reinforced plastics article when manufactured by the method or apparatus according to the invention.
The article may comprise a bath.
The shaped support may comprise a moulded plastics skin which will form the visible surface of the finished bath.
The plastics skin may be moulded from acrylic plastics material.
By way of example, specific embodiments of the invention will now be describe i with reference to the accompanying dr.~ Jings. in which:~ Figures 1 to 8 are diagrammatic cross-sections through an embodiment of apparatus according to the invention and illustrating successive stages in the manufacture of a reinforced plastics article according to an embodiment of the invention; Figures 9 to 12 are Figures corresponding to Figures 5 to 8 but illustrating an alternative embodiment of the invention; and Figures 13 to 19 are diagrammatic crosssections through another embodiment of apparatus according to the invention illustrating successive stages of yet another embodiment of method according to the invention.
The apparatus shown in the Figures 1 to 8 is for use in applying a reinforced plastics mixture to a generally convex or male support, for example the underside of a bathtub. The apparatus comprises a housing 10 slightly larger than the largest shaped article which it is desired to manufacture, and stretched across the top of the housing is a flexible air impermeable membrane 1 1.
The apparatus has means to exhaust the air from within the housing and from the starting position shown in Figure 1 the first step is to partially remove the air causing the membrane to deform to the concave shape shown in Figure 2.
The next stage, shown in Figure 3, is to spray on to the concave surface of the membrane a mixture comprising chopped glass fibre, plastics resin, and a catalyst to cause the resin to cure. The mixture is sprayed with the membrane in this shape, rather than in the shape shown in Figure 1, because this reduces the extent to which the mixture has to stretch after spraying. The depth of temperature may be used.
The invention is of course equally applicable to plastics mixtures which include fillers and/or foaming agents.

Claims (15)

1. A method of manufacturing a reinforced plastics article comprising applying a curable reinforced plastics mixture on to a flexible membrane, then deforming the membrane to urge the mixture against a shaped support, and allowing or causing the mixture to cure.
2. A method as claimed in Claim 1, in which the mixture is applied when the membrane is in a flat condition.
3. A method as claimed in Claim 1, in which the membrane is initially deformed to a first position in which it receives the mixture, and is subsequently deformed to another position in which the mixture is urged against the support.
4. A method as claimed in Claim 3, in which, in the first position, the membrane is deformed to a shape which approaches that of the shaped support, thus reducing the extent to which the surface area of the mixture has to change after application.
5. A method as claimed in Claim 4, where the shaped support is of a generally convex or male configuration, in which the membrane is deformed in the first position into a concave shape which is shallower than that necessary to accommodate the shaped support, and thus easier to spray, and is then further deformed, after the mixture has been applied, to a depth greater than that required to accommodate the shaped support, the shaped support then being inserted into the concavity and the membrane being deformed in the opposite direction to urge the mixture against the shaped support.
6. A method as claimed in Claim 4, where the shaped support is of generally concave or female configuration, in which the membrane is deformed in the first position into a convex shape of insufficient depth to completely fill the shaped support, the mixture is applied while the membrane is in the first position, the shaped support is then placed over the membrane, and the membrane is further deformed in the same direction to urge the mixture against the shaped support.
7. Apparatus for use in carrying out the method claimed in Claim 1, comprising a flexible membrane, means to deform the membrane, and means to apply a curable mixture to the membrane.
8. Apparatus as claimed in Claim 7, in which the means to deform the membrane comprises means to apply a pressure differential across the membrane.
9. A reinforced plastics article when manufactured by the method claimed in any one of Claims 1 to 6 or using the apparatus of any one of Ciaims 7 to 8.
10. A reinforced plastics article as claimed in Claim 9, comprising a bath.
11. A reinforced plastics article as claimed in Claim 10, in which the shaped support comprises a moulded plastics skin which will form the visible surface of the finished bath.
12. A reinforced plastics article as claimed in Claim 11, in which the plastics skin is moulded from acrylic plastics material.
13. A method of manufacturing a reinforced plastics article substantially as herein described with reference to Figures 1 to 8 or Figures 9 to 12 or Figures 1 3 to 19 of the accompanying drawings.
14. Apparatus for use in manufacturing a reinforced plastics article, constructed and arranged substantially as herein described, with reference to Figures 1 to 12, or Figures 13 to 19 of the accqmpanying drawings.
15. A reinforced plastics article constructed and arranged substantially as herein described, with reference to Figures 1 to 8, or Figures 9 to 12, or Figures 13 to 1 9 of the accompanying drawings.
GB8109794A 1981-03-28 1981-03-28 Forming a reinforced plastic sheet using a flexible membrane as carrier Expired GB2095606B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8109794A GB2095606B (en) 1981-03-28 1981-03-28 Forming a reinforced plastic sheet using a flexible membrane as carrier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8109794A GB2095606B (en) 1981-03-28 1981-03-28 Forming a reinforced plastic sheet using a flexible membrane as carrier

Publications (2)

Publication Number Publication Date
GB2095606A true GB2095606A (en) 1982-10-06
GB2095606B GB2095606B (en) 1985-03-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8109794A Expired GB2095606B (en) 1981-03-28 1981-03-28 Forming a reinforced plastic sheet using a flexible membrane as carrier

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2195945A (en) * 1986-08-29 1988-04-20 Kelly Tarlton S Underwater Wor Improvements in shaping

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2195945A (en) * 1986-08-29 1988-04-20 Kelly Tarlton S Underwater Wor Improvements in shaping
GB2195945B (en) * 1986-08-29 1990-01-24 Tarlton Kelly Underwater World Improvements in shaping
US5084226A (en) * 1986-08-29 1992-01-28 Tarlton Aquastar Limited Partnership Method of shaping sheets using gravity
AU622607B2 (en) * 1986-08-29 1992-04-16 Tarlton Aquastar Limited Partnership. Forming thick thermoplastic material by bending

Also Published As

Publication number Publication date
GB2095606B (en) 1985-03-20

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PCNP Patent ceased through non-payment of renewal fee