Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/305—Spray-up of reinforcing fibres with or without matrix to form a non-coherent mat in or on a mould
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/06—Fibrous reinforcements only
  • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
  • B29C70/12—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of short length, e.g. in the form of a mat
  • B29C70/14—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of short length, e.g. in the form of a mat oriented
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING 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
  • B29K2307/00—Use of elements other than metals as reinforcement
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING 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
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
  • B29K2995/0008—Magnetic or paramagnetic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING 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
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
  • B29K2995/001—Electrostatic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
  • B29L2031/3055—Cars
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2904—Staple length fiber
  • Y10T428/2907—Staple length fiber with coating or impregnation

Definitions

• the present invention relates to a method of producing a moulded product.
• the method is particularly, but not exclusively, for use in the production of a structural product.
• Such products may, for example, be structural components for use in the automobile or other industries.
• the material to be used in the method is advantageously carbon fibre, but other suitable fibres may be used.
• Carbon fibre has the advantage that it combines high strength with light weight.
• a carbon fibre matt is produced. This matt comprises a multiplicity of carbon fibres aligned in the direction in which the maximum strength of the component is desired.
• the matt may be woven or non-woven. In the former, wefts maintain fibre warps aligned and in the latter the aligned fibres may be maintained in position by transverse extending fibres wrapped around the aligned fibres.
• pre-preg The carbon fibre matt so produced, or "pre-preg” as it is sometimes called, is cut to the desired shape and then laid in the moulding tool. Resin is then applied and subsequently cured to produce the moulded product to the desired shape.
• the initial step of producing the matt and then cutting to shape is wasteful in time, energy and materials. It is an object of the invention to eliminate or mitigate these disadvantages.
• a method of producing a moulded product including the steps of supplying fibre to a robot delivery head, cutting/shearing the supplied fibres in lengths, delivering the pre-defined shortened lengths of fibre to a moulding tool so that the fibres are aligned or substantially aligned in a desired direction, and required number of layers to establish the designed thickness and strength, applying resin to the aligned fibres and curing the resin to form the moulded product.
• a moulded product comprising fibres cut to a shortened length which are aligned or substantially aligned in the same direction and coated with a cured resin.
• a continuous length of fibre is cut/sheared into shorter lengths and covered, advantageously fully encased and bonded together by resin.
• the length of the shortened fibres may vary between 10mm and 120mm.
• Preferred shortened lengths are 14mm, 28mm, 58mm and 115mm.
• the amount of fibre applied per unit area may vary between 400 and 4000 grams per square metre (gsm). Preferred rates are 1500 gsm and 2500 gsm. These preferred fibre lengths and deposition rates are based on present equipment, but may be changed to suit any given application.
• the moulding tool surface is partially evacuated to retain the fibres in the desired orientation.
• the fibre is carbon fibre it may be electro-statically charged and the moulding tool surface earthed so that mutual attraction occurs.
• the carbon fibre may be impregnated or coated with ferric powder and the moulding tool surface effectively (electro) magnetized.
• the carbon fibre may be coated with a compatible crystalline epoxy powder and the moulding tool surface heated so that on deposition, the carbon fibre is retained at the surface and the process of moulding started prior to the full application and curing of the bonding resin.
• a mist layer of compatible epoxy is applied in front of the shortened lengths of deposited carbon fibre. It is then retained at the surface and the moulding process started prior to the full application and curing of the bonding resin.
• Figure 1 diagrammatically shows a floor pan/platform for an automobile
• Figure 2 shows a section of aligned fibres produced during the method for producing the floor pan.
• Figure 3 shows a diagrammatic side elevation view in section of one form of the apparatus according to the invention. For simplicity only one set of air outlet jets are shown and in the correct relationship relative to the motion of the robot head;
• Figure 4 is a diagrammatic underplan view of the apparatus.
• Figure 5 is a perspective view to a larger scale of part of the apparatus of Figures 3 and 4.
• FIG. 1 Such a floor pan 1 is illustrated in Figure 1 and as can be seen has a complex shape.
• a continuous length of carbon fibre (not shown) is fed to a robot head at which it is cut/sheared into predetermined lengths, aligned and sprayed into a moulding tool.
• the position and angle of the head in relation to the moulding tool cavity may be varied as desired so that the individual shortened fibres are laid in the moulding tool cavity at the desired position and to the desired density and thickness.
• the fibres are preferably substantially aligned although full alignment is not necessary to achieve significant strength.
• Figure 2 diagrammatically shows a layer 30 of fibres 31 in a moulding tool.
• the surface is partially evacuated.
• Mechanical methods work with long fibres and fibre alignment reduces tow size effects. Increasing alignment enables the reduction of deposition rates which in turn leads to both process and cost savings.
• the fibres are covered and fully encased with a layer of curable resin, preferably epoxy.
• the resin is substantially cured and the finished product removed from the mould.
• a piece of material made of carbon fibre is first produced. This material may be woven or non woven but in either case it is necessary to cut the material, usually using an existing pattern before placing it in and fitting it to the moulding tool.
• This dual step of first of all producing a piece of woven/non-woven material and then subsequently cutting it to a desired shape is wasteful not only in time and effort but also in material waste. Both of these steps are effectively eliminated in the method of the invention. This can lead to a reduction in material wastage approaching 40%.
• the length of the cut/sheared fibres can be varied as desired.
• Exemplary fibre lengths are 115mm, 58mm, 28mm and 14mm.
• the superficial fibre density may also be chosen as desired.
• Exemplary fibre densities are 1500gsm (grams per square metre) and 2500 gsm.
• Tests may be carried out on products made in accordance with the above process to determine:-
• Volume fraction with respect to filamentisation Volume fraction with respect to density per unit area (effect of nesting).
• the apparatus comprises a housing 1.
• This has a downwardly divergent shape in side elevation and a lozenge shape in cross section (as can be seen from Figure 4).
• the proportions of the housing 1 contribute to the consistent and smooth distribution of shortened fibres.
• the lozenge shape outlet/delivery slot in cross section (as shown in Figure 4) determines the principal alignment of the alignment of the shortened fibres when deposited into the moulding tool.
• the lozenge shape comprises two parallel sides 2 and 3 joined at opposite ends respectively by semi-circular portions 4 and 5.
• a cutting/shearing head 6 is disposed within the housing 1.
• the head 6 comprises two rollers 7 and 8 defining a nip 9 therebetween.
• Roller 7 is a pressure roller and comprises a cylindrical tyre 10 mounted on a cylindrical support 11.
• the tyre is made of rubber or other suitable material.
• Roller 8 is a blade housing roller. This comprises a cylindrical housing 12. Blades are retained in the blade housing roller 8 which is made from hard but resilient material such as rubber The diameter of the two rollers 7 and 8 is the same.
• Housing 12 is formed with a number of through elongate slots 13 extending axially of the cylinder of the housing and disposed at circumferentially spaced intervals around the cylinder.
• a cam 14 mounted on a camshaft 15 via splines (not shown). The camshaft is disposed to be driven by a stepper motor (not shown) at one of a range of speeds.
• a plurality of blades 16 (only one shown) is associated with respective slots 13, and are disposed to be extended through their corresponding slots 13 sequentially by the action of the cam as it is rotated within the housing 8 by means of the camshaft 15 driven by the stepper motor in order to cut/shear fibre passing through the nip formed between the rollers 7 and 8.
• the resilience of the rubber of the housing 8 allows that blade to return to its retracted inoperative position.
• the number of slots 13 and blades 16 may be varied as desired.
• the cam lift provided by the cam 14 is circa 2 to 3mm but again this may be varied as desired.
• the diameter of the rollers 7 and 8 is circa 30mm but this may also be varied as desired.
• the cam has a single lobe but multi lobe cam may be used if shorter fibre lengths are desired.
• the cam lift for the cutting blade must be sufficient to cut through the fibre and have accommodation of circa 0.2mm in the pressure roller (7).
• rollers (7) and (8) can be adjusted so that the nip on the chosen fibre diameter is adequate to ensure consistency and meet the cutting control criteria described above.
• the rollers 7 and 8 are driven at the same speed which is independent of the camshaft speed.
• the circumferential speed of the surfaces of the rollers determines the rate of feed of fibre fed through them.
• the precise length of fibre fed between the rollers and cut/sheared by the cam actuated blades extending through their corresponding slots is determined.
• the rollers 7 and 8 project the shortened lengths towards the delivery slot.
• the air jets through apertures 20 are activated as trailing elements relative to the movement of the robot head and the air jets through the apertures 21 are activated on the leading face of motion.
• the purpose of the air jets through apertures 20 is to spread the lengths of fibre. This spreading action starts whilst the fibres are still partially retained by the rollers and prior to them being cut and free from the roller nip and projected towards the delivery slot.
• Apertures 21 are disposed at a lower level than apertures 20.
• the purpose of the air jets through apertures 21 is to rotate and align the shortened lengths of fibre to the direction of and within an outlet slot 22 which is defined between parallel walls 2 and 3.
• the carbon fibre may be impregnated or coated with ferric powder and the moulding tool surface (electro) magnetized.
• the carbon fibre may be coated with a compatible crystalline epoxy powder and the moulding tool surface heated so that on deposition, the carbon fibre is retained at the surface and the mould integration started prior to the full application and curing of the bonding resin.
• a mist layer of compatible epoxy is applied in front of the shortened lengths of deposited carbon fibre. It is then retained at the surface and the moulding process started prior to the full application and curing of the bonding resin.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Moulding By Coating Moulds (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Citations (3)

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• 2006
  • 2006-11-18 GB GBGB0623047.8A patent/GB0623047D0/en not_active Ceased
• 2007
  • 2007-11-16 CN CN2007800501357A patent/CN101588914B/zh not_active Expired - Fee Related
  • 2007-11-16 WO PCT/GB2007/004392 patent/WO2008059273A1/en not_active Ceased
  • 2007-11-16 US US12/515,307 patent/US8591781B2/en active Active
  • 2007-11-16 JP JP2009536796A patent/JP5416592B2/ja not_active Expired - Fee Related
  • 2007-11-16 EP EP07824611.3A patent/EP2125340B1/en not_active Not-in-force

Patent Citations (3)

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