Patent Description:
Fibre reinforcement material can be laid up with continuous tape using a placement machine and consolidating with a roller or manually by picking up and placing whole pre-cut plies and consolidating under vacuum after a specified number of plies until a pre-form is formed. The pre-form is placed in an autoclave, which cures the pre-form under pressure and heat.

<CIT> discloses an installation comprising a forming die, a gripping tool capable of being mounted, for example, on the articulated arm of a robot. The forming die comprises a flexible membrane, equipped with suction suckers which grip pre-cut elementary layers. A vacuum circuit enables the membrane to be pressed up against a counter-shape placed behind the latter, in order to shape the elementary layer picked up. When the tool is brought onto the die, a pressure source acts on the membrane in order to compact the elementary layer on the die. A suction system keeps this layer on the die, after releasing the suction via the suckers.

According to a first aspect, there is provided a lay-up apparatus for laying up fibre reinforcement material, the lay-up apparatus comprising: a lay-up tool defining a lay-up surface; and a placement head having a flexible membrane which is conformable to the lay-up surface, and a membrane vacuum port extending through the membrane and configured to hold a ply against the membrane when suction is applied through the membrane vacuum port; wherein the placement head is configured to cooperate with the lay-up tool to form an airtight chamber between the membrane and the lay-up tool when a ply is held against the membrane (i.e. between the membrane, an opposing surface of the lay-up tool and side walls of the placement head); and wherein the lay-up tool comprises a consolidation vacuum port configured to permit evacuation of the airtight chamber to cause the membrane and ply to move towards the lay-up surface.

The membrane may be configured to seal with a ply of fibre reinforcement material around the vacuum port, when suction is applied through the membrane vacuum port.

The membrane vacuum port is moveable relative a support structure of the placement head from a ply holding position to a consolidation position, such that the moveable membrane vacuum port further permits the membrane and the ply to conform to the lay-up surface as they move towards the lay-up surface during evacuation of the chamber, when the placement head cooperates with the lay-up tool. When the placement head cooperates with the lay-up tool, and the vacuum port is in the holding position, the membrane and ply may be spaced apart from the lay-up surface with the airtight chamber disposed between them.

The placement head may comprise a port guide to guide movement of the moveable membrane vacuum port from the ply holding position to the consolidation position. The moveable membrane vacuum port may be biased to the ply holding position. The membrane vacuum port is controllably moveable between the ply holding position and the consolidation position to mechanically clamp the ply between the membrane and the lay-up tool in the consolidation configuration.

The lay-up apparatus may comprise a controller configured to control a lay-up operation. The controller may be configured to control movement of the placement head between picking up a ply and cooperating with the lay-up tool.

The controller may be configured to control suction through the membrane vacuum ports to control picking up and holding of a ply against the membrane. The controller may be configured to control evacuation of the airtight chamber through the consolidation vacuum port.

The lay-up tool may comprises heaters for heating the lay-up surface.

The lay-up apparatus may comprise a pick-up tool configured to receive a ply to be picked up by the placement head, and wherein the placement head is configured to cooperate with the pick-up tool so that the membrane of the placement head is in contact with the ply on the pick-up tool.

According to a second aspect, there is provided a method of laying up fibre reinforcement material with a lay-up apparatus of the first aspect, the method comprising: picking up and holding a ply against the membrane of the placement head by applying suction through the membrane vacuum port; moving the placement head to position the ply over the lay-up surface of the lay-up tool, whereby the placement head cooperates with the lay-up tool to form an airtight chamber between the lay-up tool and the membrane; and evacuating the airtight chamber through the consolidation vacuum port in the lay-up tool such that the membrane and the ply conform to the lay-up surface to compact the ply against the lay-up surface.

The method comprises controlling movement of a membrane vacuum port to the consolidation position to mechanically clamp the ply between the membrane and the lay-up tool after moving the placement head to the lay-up tool and before evacuating the airtight chamber.

The method may comprise heating the lay-up surface during evacuation of the airtight chamber.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which:.

<FIG> and <FIG> show a lay-up apparatus <NUM> comprising a pick-up tool <NUM>, a lay-up tool <NUM> and a placement head <NUM>.

The pick-up tool <NUM> comprises a pick-up surface <NUM> configured to receive a ply <NUM> to be picked up in a lay-up operation (described with reference to <FIG> below). In this example, the ply <NUM> is a layer of fibre reinforcement material provided with a disposable backing layer, such as a film of plastic. <FIG> shows the pick-up tool <NUM> with a ply <NUM> received on the pick-up surface <NUM>, with the backing layer of the ply <NUM> disposed on an opposing side to the pick-up surface <NUM>. In this example, the pick-up surface <NUM> is planar (i.e. flat) so as to be able to receive a flat ply <NUM> without distorting the ply <NUM>, such as by wrinkling, folding or bridging.

The lay-up tool <NUM> comprises a lay-up surface <NUM> which in this example has a different profile to the pick-up surface <NUM> of the pick-up tool <NUM>. The lay-up surface may have a complex three-dimensional profile. In this example, the lay-up surface <NUM> diverges downwards from a central portion such that the central portion of the lay-up surface <NUM> is higher than outer portions of the lay-up surface <NUM>. In other examples, the lay-up surface may have any three-dimensional profile. The lay-up surface <NUM> is configured to receive a ply <NUM> such that it conforms to the profile of the lay-up surface <NUM>.

The lay-up tool <NUM> comprises a lay-up support <NUM> which encloses the lay-up surface <NUM>, with a consolidation recess <NUM> disposed between the lay-up support <NUM> and the lay-up surface <NUM>.

The lay-up tool <NUM> comprises two consolidation vacuum ports <NUM> which extend from a surface of the consolidation recess though the lay-up tool <NUM>. The consolidation vacuum ports <NUM> are configured to be connected to a vacuum pump or other low pressure source so that air can be drawn from above the lay-up surface <NUM> through the consolidation vacuum port <NUM>. In other examples, there may be more or fewer consolidation vacuum ports, and they may be disposed in any suitable location in the lay-up tool.

In this example, the lay-up tool <NUM> further comprises heaters <NUM> (shown in <FIG>) which are configured to heat the lay-up tool <NUM> to thereby heat the lay-up surface <NUM>. The heaters <NUM> are positioned below the lay-up surface <NUM>. In other examples, the heaters <NUM> may be positioned anywhere on the lay-up tool <NUM>. A heated lay-up surface <NUM> may impart heat to a ply <NUM> laid up on the lay-up surface <NUM>, thereby improving the consolidation of the ply <NUM>, during a lay-up operation.

The placement head <NUM> comprises a support structure <NUM> and a flexible membrane <NUM> which is conformable to a surface. In this example, the support structure <NUM> is in the form of a housing having an open end so as to define a partially-enclosed cavity and be configured to partially receive the pick-up tool <NUM> or the lay-up tool <NUM>. In this simplified example, the housing is generally cuboidal with an upper plate <NUM> and downwardly projecting sides <NUM>, with an open lower end. The support structure <NUM> surrounds the membrane <NUM>, and the membrane <NUM> is attached at its periphery to the sides <NUM> of the support structure <NUM> near to the upper plate <NUM>. In other examples, the support structure may be of any suitable shape.

The membrane <NUM> is elastic and made from silicon. In some examples, the membrane may be made from rubber, or any other elastic material. In other examples, the membrane may not be elastic, and may be merely flexible.

The placement head <NUM> further comprises a plurality of membrane vacuum ports <NUM> which extend through the membrane <NUM>, away from the enclosed space, and through openings in the plate <NUM> of the support structure <NUM>. In this example, there are three membrane vacuum ports <NUM> arranged in a line. In other examples, there may be more or fewer membrane vacuum ports, and they may be arranged in any suitable configuration.

The membrane vacuum ports <NUM> are configured to be connected to a vacuum pump so that air can be drawn from below the membrane <NUM> (i.e. from the enclosed space side of the membrane <NUM>) through the respective membrane vacuum port <NUM>. The placement head <NUM> is configured to hold a ply <NUM> against the membrane <NUM> when suction is applied through the membrane vacuum ports <NUM>.

The membrane vacuum ports <NUM> are configured so that a seal is formed between a ply <NUM> of reinforcement material and the membrane <NUM> around the membrane vacuum port <NUM> when suction is applied through the membrane vacuum port <NUM>. The seal may be formed between the backing layer of the ply <NUM> and the membrane <NUM> when present, or between the ply and the membrane. This enables the ply <NUM> to be picked up by the placement head <NUM> without the need for suction cups, with the membrane acting to provide more uniform support to the ply than may be provided by spaced apart suction cups alone. In some examples, the membrane vacuum ports may terminate with suction cups configured to form a seal with a ply. In other examples, the membrane vacuum ports may extend through the membrane and terminate with a plate on an inner surface of the membrane. In such examples, the membrane vacuum ports may be configured so that a seal is formed between a ply of reinforcement material and the plate of the membrane vacuum port.

The placement head <NUM> is configured to cooperate with the pick-up tool <NUM> such that the membrane <NUM> comes into contact with the backing layer of a ply <NUM> disposed on the pick-up surface <NUM> of the pick-up tool <NUM>. Therefore, when the placement head <NUM> is cooperating with the pick-up tool <NUM>, it can pick up a ply <NUM> disposed on the pick-up surface <NUM> and hold it against the membrane <NUM> by applying suction through the membrane vacuum ports <NUM>.

The placement head <NUM> is configured to cooperate with the lay-up tool <NUM> by forming a seal between the projecting sides <NUM> of the support structure <NUM> and the lay-up support <NUM> of the lay-up tool <NUM>. Therefore, when a ply <NUM> is held against the membrane <NUM> of the placement head <NUM>, thereby sealing the membrane vacuum ports <NUM> in the membrane <NUM>, and the placement head cooperates with the lay-up tool <NUM>, an airtight chamber <NUM> is formed between the membrane <NUM> and the lay-up tool <NUM> (best shown in <FIG>).

In this example, the membrane vacuum ports <NUM> of the placement head <NUM> are moveable relative the support structure <NUM> between a ply holding position and a consolidation position. The membrane vacuum ports <NUM> may be pivotable within the openings of the plate <NUM> of the support structure <NUM>, and are linearly movable through the openings of the plate <NUM>.

<FIG> and <FIG> shows each of the membrane vacuum ports <NUM> in respective ply holding positions. In this example, each of the vacuum ports is configured that when all of the vacuum ports are in their respective ply holding positions their openings are aligned in a common plane so that they can easily pick up a ply <NUM> from the flat pick-up surface <NUM> of the pick-up tool <NUM>. <FIG> shows each of the membrane vacuum ports <NUM> in respective consolidation positions. The consolidation position of a vacuum port <NUM> is the position when it is compacting a ply <NUM> against the lay-up surface <NUM> of the lay-up tool <NUM>, or against plies laid up on the lay-up tool <NUM>. The consolidation position in this example corresponds to the respective ports not being aligned in a common plane. It will be appreciated that there may be any number of consolidation positions corresponding to the position of respective ports when compacting a ply.

Having a plurality of freely moveable membrane vacuum ports <NUM> allows the membrane <NUM> to more precisely conform to a surface, such as the lay-up surface <NUM>, as the membrane <NUM> is not constrained by its attachment to the membrane ports <NUM>. In this example, all three of the membrane vacuum ports <NUM> are movable relative the support structure <NUM>. In some examples, none of the membrane vacuum ports may be moveable relative the support structure or only some of the membrane vacuum ports may be moveable relative the support structure.

In this example, the support structure <NUM> comprises a port guide <NUM> which is configured to guide the central membrane vacuum port <NUM> to constrain it to linear movement. The port guide <NUM> comprises linear protrusions from the plate <NUM> and a guide bar coupled to the central membrane vacuum port <NUM> and cooperating with the linear protrusions. In some examples, there may be more than one port guide, or the port guide may be omitted. In other examples, a port guide may be coupled to any one or to more than one of the membrane vacuum ports.

In this example, the port guide <NUM> also comprises driving means (not shown) to controllably move the central membrane vacuum port <NUM> between its ply holding position and the consolidation position. The controllable movement of the membrane vacuum port <NUM> enables the placement head <NUM> to mechanically clamp a ply <NUM> between the membrane <NUM> and the lay-up surface <NUM> of the lay-up tool <NUM>, when the placement head <NUM> is cooperating with the lay-up tool <NUM> (as shown in <FIG>). In some examples, the membrane vacuum port may be controllably moved to clamp a ply between the membrane and the pick-up tool to pick up a ply from the pick-up tool. In other examples, there may be no driving means.

In this example, the movable membrane vacuum ports <NUM> are biased to the ply holding position, so that when they are induced to move away from the ply holding position by an external force, they return to the ply holding position once the external force is removed. The vacuum ports may be biased by virtue of being coupled to the membrane, which may be an elastic material biased to return to a substantially planar form when returned in the placement head.

In this example, lay-up apparatus <NUM> further comprises a controller <NUM>. The controller <NUM> is configured to control movement of the placement head <NUM> and to control suction through the consolidation and membrane vacuum ports <NUM>, <NUM>. The controller <NUM> also controls movement of the driven membrane vacuum port <NUM> (i.e. the central membrane vacuum port in this example) to mechanically clamp a ply layer <NUM> between the membrane <NUM> and the lay-up surface <NUM>.

<FIG> is a flow chart showing steps of a method <NUM> of performing a lay-up operation to lay up fibre reinforcement material using the lay-up apparatus <NUM>.

At the beginning of the lay-up operation, a ply <NUM> is disposed on the pick-up surface <NUM> of the pick-up tool <NUM> with the backing layer disposed on the surface opposing the pick-up surface <NUM>. In box <NUM>, the method includes moving the placement head <NUM> to cooperate with the pick-up tool <NUM> as shown in <FIG>. As explained above, when the placement head <NUM> cooperates with the pick-up tool <NUM>, the membrane <NUM> is in contact with the backing layer of the ply <NUM>.

In box <NUM>, the method comprises applying suction though the membrane vacuum ports <NUM> so that a seal is formed between the backing layer of the ply <NUM> and the membrane <NUM> around each of the membrane vacuum ports <NUM>. The seal ensures that a vacuum is formed between the ply <NUM> and the membrane <NUM> around the vacuum ports <NUM>, such that the ply <NUM> is held against the membrane while suction is applied through the membrane vacuum ports <NUM>.

In box <NUM>, the method comprises moving the placement head <NUM> to cooperate with the lay-up tool <NUM> as shown in <FIG>. Since the ply <NUM> is held against the membrane <NUM> by the suction through the membrane vacuum ports <NUM>, the ply <NUM> is carried with the placement head <NUM> to the lay-up tool <NUM>.

When cooperating with the lay-up tool <NUM>, with a ply <NUM> held against the membrane <NUM>, the placement head <NUM> forms an airtight chamber <NUM> between the membrane <NUM> and the lay-up tool <NUM>. The projecting sides <NUM> of the support structure <NUM> form a seal with cooperating surfaces of the lay-up tool <NUM> with an O-ring or other suitable seal, to thereby form the airtight chamber <NUM>.

In box <NUM>, the method comprises driving the central membrane vacuum port <NUM> to move from the ply holding position to the consolidation position, such that it clamps the ply <NUM> between the membrane <NUM> and the lay-up tool <NUM>, as shown in <FIG>.

In box <NUM>, the method comprises applying suction through the consolidation vacuum port <NUM> of the lay-up tool <NUM> to evacuate the chamber <NUM>. Since suction is still being applied through the membrane vacuum ports <NUM>, the ply <NUM> is sealed against the membrane <NUM>. Therefore, the membrane <NUM> is forced to deform and move towards the lay-up surface <NUM> to conform with the lay-up surface, thereby forcing the ply <NUM> to conform with the lay-up surface <NUM> as shown in <FIG>. In this example, the membrane vacuum ports <NUM> move freely to a consolidation position under force of the vacuum (i.e. through the consolidation vacuum port) to permit more precise conformance.

The membrane <NUM> therefore compacts the ply <NUM> against the lay-up surface to de-bulk the ply <NUM>. In some examples, the lay-up surface may be a top layer of a ply or of a plurality of plies which have already been laid up.

In box <NUM>, during evacuation of the chamber <NUM>, the heaters <NUM> heat the lay-up tool <NUM> so that the lay-up surface <NUM> is heated, thereby transferring heat to the ply <NUM> on the lay-up surface <NUM>. This improves consolidation of the ply <NUM> on the lay-up surface <NUM>.

In box <NUM> the method comprises stopping applying suction through the consolidation and membrane vacuum ports <NUM>, <NUM> when the ply <NUM> has been compacted. Stopping applying suction through the membrane vacuum ports <NUM> breaks the seal between the ply <NUM> and the membrane <NUM> such that the ply <NUM> is no longer held against the membrane <NUM>.

Stopping applying suction through the consolidation vacuum port <NUM> permits venting of the chamber <NUM> so that air may re-enter the chamber <NUM> (i.e. through the port or an alternative passageway, which may be selectively opened). The membrane vacuum ports <NUM> are biased to the ply holding position, and therefore return to the ply holding position when the vacuum in the chamber <NUM> is released.

The placement head <NUM> can now be moved away from the lay-up tool <NUM>, and the backing layer can be removed from the ply <NUM>. The lay-up operation <NUM> may then be repeated as many times as necessary to form a pre-form, and to de-bulk each ply layer <NUM> which is applied to the lay-up tool <NUM>.

When the last ply <NUM> is laid up and the pre-form is formed, the lay-up tool <NUM> may be placed in an oven or autoclave to cure the pre-form.

Claim 1:
A lay-up apparatus (<NUM>) for laying up fibre reinforcement material, the lay-up apparatus (<NUM>) comprising:
a lay-up tool (<NUM>) defining a lay-up surface (<NUM>); and
a placement head (<NUM>) having a flexible membrane (<NUM>) which is conformable to the lay-up surface (<NUM>), and a membrane vacuum port (<NUM>) extending through the membrane (<NUM>) and configured to hold a ply (<NUM>) against the membrane (<NUM>) when suction is applied through the membrane vacuum port (<NUM>);
wherein the placement head (<NUM>) is configured to cooperate with the lay-up tool (<NUM>) to form an airtight chamber (<NUM>) between the membrane (<NUM>) and the lay-up tool (<NUM>) when a ply (<NUM>) is held against the membrane (<NUM>);
wherein the lay-up tool (<NUM>) comprises a consolidation vacuum port (<NUM>) configured to permit evacuation of the airtight chamber (<NUM>) to cause the membrane (<NUM>) and ply (<NUM>) to move towards the lay-up surface (<NUM>); and
wherein the membrane vacuum port (<NUM>) is controllably moveable relative a support structure (<NUM>) of the placement head (<NUM>) from a ply (<NUM>) holding position to a consolidation position, such that the moveable membrane vacuum port (<NUM>) further permits the membrane (<NUM>) and the ply (<NUM>) to conform to the lay-up surface (<NUM>), as they move towards the lay-up surface (<NUM>) during evacuation of the chamber (<NUM>), when the placement head (<NUM>) cooperates with the lay-up tool (<NUM>), and to mechanically clamp the ply (<NUM>) between the membrane (<NUM>) and the lay-up tool (<NUM>) when the placement head (<NUM>) cooperates with the lay-up tool (<NUM>).