Patent ID: 12226964

DETAILED DESCRIPTION OF DRAWINGS

FIG.1shows a spreading apparatus1for fibre-reinforced composite tapes, according to an example embodiment. The spreading apparatus1is useful for spreading fibre-reinforced composite tapes, such as carbon fibre-reinforced prepreg tapes used in ATP manufacturing processes. The spreading apparatus1comprises an input side to receive an incoming tape to be spread, and an output side from which tape is delivered after spreading. The apparatus further comprises a tape heater150on the input side to in use apply heat to a tape, and a tape spreader100on the output side to in use to apply contact pressure to the heated tape to thereby spread the tape. The tape heater150applies heat to the incoming tape in order to raise its temperature and render it more easily deformable under contact pressure from the tape spreader100.

Contact pressure from the tape spreader100reduces the in-plane thickness of the tape, spreading the tape out so that it is of larger width when delivered from the output side of the spreading apparatus1, as compared to the width of the tape received at the input side. By controlling the spreading apparatus to spread the tape to different widths, the incidence of gaps, overlaps and wrinkles in composite components that are manufactured from the tape, such as through an ATP process, can be reduced. This is particularly advantageous, as described in more detail later, when the tape is used in the manufacture of composite components comprising at least one curved surface.

The tape heater150comprises a platen160which is heated with three heater cartridges171,172,173. In the tape spreader1ofFIG.1the heater cartridges171,172,173are electrical heating elements, controlled to maintain the temperature of the platen160at a sufficiently high temperature that tape received at the input side is heated as it moves across the platen160, reaching the melting point, or other suitable predetermined temperature according to the nature of the matrix material of the composite tape, by the point at which the tape spreader100applies contact pressure thereto. For example, the tape may comprise a thermoplastic resin matrix comprising PEEK, and in this case the tape heater150is arranged so that the heater cartridges171,172,173maintain the platen160at 343° C., corresponding to the melting temperature of PEEK.

The tape spreader100comprises a compaction shoe110that is movable in to and out of contact with sections of tape as the tape passes across the platen160, between the input side of the tape spreading apparatus1and the output side. The compaction shoe110is of fixed geometry, in the example embodiment ofFIG.1comprising a cylindrical form that is arranged generally perpendicular to the direction of movement of tape through the spreading apparatus1. The platen160is generally planar, providing a smooth, uninterrupted surface over which the tape passes, is heated by, and against which it is pressed by the compaction shoe110. The compaction shoe110is aligned parallel to the surface of the platen160to enable an even pressure to be applied across the width of the tape. The pressure applied to the tape by the tape spreader100is controlled by applying different weights to the top of the compaction shoe110.FIG.1shows part of a weight112.

In order to reduce the chance of damage to the fibres in the tape as the tape is spread, the surfaces of the tape spreader100that contact the tape comprise polished H13 tool steel. A layer of non-stick coating applied thereto serves to further reduce problems associated with the tape sticking to the surfaces of the tape spreader100. It will be appreciated that the platen160and tape-heating surface may comprise a single piece of material.

By conservation of volume of material, the reduction in thickness of the tape caused by the pressure from the compaction shoe110and the platen160on the top and bottom sides thereof results in a reduction in in-plane thickness of the tape, and therefore an increase in width of the tape as the tape is spread. As will be appreciated, by controlling the temperature, amount of pressure and the time over which pressure is applied as the tape passes between the input side and the output side of the tape spreading apparatus1, it is possible to control the amount of spreading that takes place, including such that a tape of constant width and thickness received at the input side of the tape spreading apparatus may be delivered from the output side with varied width and thickness along its length.

FIG.2shows a spreading apparatus2for fibre-reinforced composite tapes according to another example embodiment. The spreading apparatus2comprises a tape heater250on the input side to in use apply heat to a tape, and a tape spreader200on the output side to in use to apply contact pressure to the heated tape to thereby spread the tape, these components generally corresponding to the equivalent components shown inFIG.1. The tape heater250comprises a heat source incorporated with the platen260, the platen providing a heating surface which raises the temperature of incoming tape as the tape passes over it. The tape spreader200, however, comprises two spreading stages. An actuator unit220enabling the amount of contact pressure and the way that the pressure is applied to be more readily controlled as tape passes through the spreading apparatus2. The tape spreading apparatus2comprises an actuator clamp arrangement222to stabilize the actuators of the actuator unit220.

Additionally, the spreading apparatus2comprises an incoming guide230and an outgoing guide232that in use respectively guide tape as it is received at the input side of the spreading apparatus2and delivered from the output side of the spreading apparatus2. The incoming guide230is positioned on the input side of the spreading apparatus2and stabilizes the incoming tape, and the outgoing guide232is positioned on the output side of the spreading apparatus2and is configured to stabilize the outgoing tape. The incoming guide230and the outgoing guide232are self-adjusting actuated guides of the type generally known for use in tape handling operations.

The first tape spreading stage comprises a cylindrical roller aligned parallel to the surface of the platen260, but with its axis perpendicular to the direction of movement of tape through the tape spreading apparatus2. The pressure imparted on the tape by the first spreading stage is governed by a first actuator220. The first actuator is pneumatic. The advantage of pneumatic actuators over other governing means such as weights is that pneumatic actuators may vary the pressure applied to the tapes in a consistent and straightforward fashion.

The second tape spreading stage comprises a compaction shoe with a generally planar compaction surface to contact the tape and press it against the platen. The pressure imparted on the tape by the second spreading stage is governed by a second actuator220. The second actuator is pneumatic. The compaction surface of the compaction shoe is arranged generally parallel to the platen. The compaction shoe comprises curved portions alongside the planar surface, curving away from the platen. The curved portions are generally smoothly curved, to reduce the impact that the edges of the planar surface have on the surface of the tape as it is compress, and/or as the compaction shoe is separated from the tape after applying pressure thereto.

As mentioned for the tape spreading apparatus1ofFIG.1, through control of the amount of heating, the amount and way that pressure is applied to the tape to regulate the amount of spreading that takes place in the spreading apparatus2.

The example embodiments may employ sensors and feedback control mechanisms, to ensure a desired amount of spreading is achieved. A controller/processor in the form of a microcontroller enables different settings for the desired amount of spreading to be provided for the spreading apparatus in use as tape passes therethrough. In addition, feedback control variables can also be readily set according to desired operational characteristics such as speed of operation or an acceptable tolerance in the dimensions of the spread tape output from the spreading apparatus. In combination with, or separately from feedback control, empirical techniques may be used to determine the spreading effect of different heating and pressure conditions on different types of tape.

Considering the application of pressure, both a pressure measurement and position measurement for components of the tape spreader, e.g. the position of the compaction shoe relative to the platen, offer a way of regulating the effect of the spreading apparatus on the tape.

Some possible modifications to the spreading apparatuses described herein will now be explained. Whereas the tape spreaders in the example embodiments shown in the Figures have one compaction shoe to press sections of tape against the platen, more than one compaction shoe may be provided. The compaction shoes may have different geometries from one another, according to the amount of spreading to be performed in separate spreading operations. Single roller spreading stages are envisaged as within the present disclosure, as are tape spreaders comprising a plurality of rollers, either in series spreading arrangement to compress the tape against a platen, or opposed rollers to spread the tape as it passes therebetween. The roller options carry with them the risk of damage to the tape by adherence and pulling up of fibres, in a way that is not possible with compression by use of a compaction shoe.

Although heating the tape by contact with a platen enables good stability/temperature regulation at the point at which the tape is spread, other tape heaters/heating methods are also possible, either separately or in combination. For example, a laser and/or infrared heaters, or other radiative heating elements may be used, and/or hot-gas/hot-air. A plurality of heat sources may be used. In one example, the heat source may be configured with a temperature sensor, and the heat source may maintain the heated surface at a steady temperature using feedback control.

The tape heater may comprise a heat source arranged to supply heat indirectly to an incoming tape, for example to heat a surface or thermal mass component that applies heat to the tape. The tape heater may be centrally located between the input side and the output side to in use apply heat to a tape. Application of heat to a tape and application of contact pressure to the tape may occur simultaneously and/or sequentially.

In addition to control, either feedback control or otherwise, of the application of heat and pressure to regulate spreading of tape by the spreading apparatuses described herein, the all embodiments may include a tape feed controller to regulate the movement of tape from the input side of the spreading apparatus to the output side thereof. The tape feed controller may in certain embodiment be configured to move the tape in such a way that no deformation takes place in accordance with the position or movement of the tape. In other embodiments, the tape feed controller may regulate the tension on the tape such that additional elongation takes place. This introduces a further control variable regulating the amount of spreading, as well as improving reproducibility of the tape spreading operation and/or introduces the possibility of changes to fibre orientation being introduced to the tape as part of the tape spreading process.

As tapes are spread and the thickness reduces, fibres within the tape slip with respect to each other and realign accordingly. The spreading apparatus has the ability to vary tape width during the production process of a component from fibre-reinforced tape. Accordingly, the performance benefits of either lighter or stronger/stiffer structures may be realized by tailoring thickness distributions to meet specific performance requirements, including tuning thickness and fibre orientation independently of each other. Additionally, the performance benefits either lighter or stronger/stiffer structures are realized by minimizing stress and strain concentrations due to local fibre cuts (ply drops) thereby improving strength and damage tolerance properties. Spreading also allows tapes to be more spread over doubly curved surfaces (non-zero Gaussian curvature) without the gaps and overlaps associated with laying constant width tapes on doubly curved surfaces. Example applications include (but are not limited to) nacelles, radomes, twisted fan blades, aircraft wing surfaces and wind turbine blade surfaces. These issues are illustrated inFIGS.3and4.FIG.3shows related steered carbon fibre tows with gaps in between.FIG.4shows an example of a composite component which varies in width from base to tip over a doubly curved surface that is difficult to produce to high quality using related tape placement methods.

FIG.5shows a flowchart of a method of spreading fibre-reinforced composite tapes, according to an example embodiment.

As shown, at step S502, the method comprises receiving an incoming tape to be spread. At step in S504, the method comprises a step of applying heat to the tape. At step S506, the method comprises applying contact pressure to the heated tape, thereby spreading the tape. As shown in S508, the method further comprises a step of outputting spread tape.

It will be appreciated, by this method of a fibre-reinforced tape has its in-plane thickness reduced, but its width is increased. Applying heat to the incoming tape in order to raise its temperature renders the tape more easily deformable under contact pressure. Suitably, applying heat may be performed by conduction, radiation or a combination of both, such that a predetermined temperature is reached, according the materials from which the tape is made.

It will be also appreciated that the step of applying heat to a tape and the step of applying contact pressure to the heated tape, thereby spreading the tape may occur simultaneously and/or sequentially. Furthermore, the step of applying contact pressure to the heated tape, thereby spreading the tape may occur more than once, i.e. a plurality of compression operations are envisaged to achieve the desired spreading effect. The spreading apparatus of any embodiment described herein may be used to perform the above-described method of spreading.

The methods and apparatus described are particularly suited to spreading fibre-reinforced composite tapes in which the tape includes a matrix of thermoplastic resin material. The tapes may also comprise carbon fibre, such as prepreg resin-carbon fibre composite tapes. Examples of relevant fibre-reinforced materials those including fibres of carbon, glass and aramid. Thermoplastic resin materials that are relevant include thermoplastic polymers such as PEEK, PEKK, PPS, PP and PA (Nylon). Suitable heating and pressuring of fibre-reinforced tapes in which the tape includes a thermosetting component, such as a thermosetting polymer matrix are also envisaged as providing a tape spreading benefit.

FIG.6shows a schematic of a spreading apparatus for fibre-reinforced composite tapes, according to an example embodiment, as part of the ATP process. The apparatus comprises an input side to receive an incoming tape to be spread, and an output side from which tape is delivered after spreading. The apparatus comprises a tape heater650to in use apply heat to a tape, and a tape spreader600to in use to apply contact pressure to the heated tape to thereby spread the tape. A spreading apparatus as described herein may be attached to the ATP apparatus in the manner shown. Accordingly, ATP apparatus for in-situ consolidation of fibre-reinforced composite tapes may comprise the spreading apparatus of any preceding embodiment. The skilled person will appreciate that the spreading apparatus of any preceding embodiment may be used in any of Advanced Fibre Placement (AFP) and ATP processes. An example of an ATP process is Laser-Assisted Tape Placement (LATP). ATP processes referred to generally in this document suitably also include processes known as Automated Tape Laying, Automated Fibre Placement, Assisted Tape Placement or Automated Tow Placement.

FIG.7shows an Automated Tape Placement apparatus that comprises a spreading apparatus for fibre-reinforced composite tapes, according to an example embodiment. The ATP apparatus for in-situ consolidation of fibre-reinforced composite tapes comprises a tape spool unit720, a controller unit and a head unit722. The spreading apparatus of any preceding embodiment is attachable to the head unit722of the ATP apparatus. Accordingly, the ATP apparatus with the spreading apparatus as described herein are operable to form a composite component. The method of forming a composite component comprises spreading a fibre-reinforced composite tape prior to consolidation in the ATP process using the ATP process apparatus with a spreading apparatus as described herein.

Although the exemplary embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.