Patent Description:
In some manufacturing steps of a composite parts, the parts must be subjected to a homogeneous pressure during the application.

Current devices for applying vacuum pressure to an assembly provide a support on which a composite part or assembly may be arranged, a vacuum bag to be applied over the support and composite parts, said vacuum bag being sealed to the support, and a port in the vacuum to apply a vacuum source to a volume comprised between the support and the vacuum bag.

Such devices do not provide an optimal extraction of gases comprised between the support and the vacuum bag.

<CIT> discloses a non-metallic vacuum probe for elevated temperature service having a probe body portion for coupling to a vacuum line. The probe body portion is coupled through a washer shaped low friction bearing surface and gasket for sealing to a probe flange portion. Interconnection of probe body portion and probe flange portion is provided through lug and ramp means. The probe flange portion includes vacuum channels on the bottom major surface region for vacuum bag and blanket curing of plastic components or panels in autoclaves or ovens.

<CIT> discloses an apparatus for forming fiber reinforced resin structures In detail, invention includes a fluid impervious outer first sheet. A mold surface is includes upon which can be supported a lay-up of at least one layer of fibrous material, and over which can be placed the first fluid impervious outer sheet and its edges marginally sealed upon the mold surface to form a chamber. A first vacuum port for drawing a vacuum upon the chamber is located in proximity to the lay-up. A first distribution medium is positioned between the fabric lay-up and the fluid impervious outer sheet for distributing resin into the lay-up. A second fluid impervious sheet is located between the first distribution medium and the first impervious sheet. A resin inlet port extends from the exterior of the chamber through the first and second impervious sheets and is in communication with the first distribution medium. A second distribution medium is located between the first and second impervious sheets for providing a flow path from the lay-up to the outlet port. A second vacuum port extends from the exterior of the first impervious sheet to the chamber and in communication with the second distribution medium.

The invention aims to provide an efficient vacuum device and method.

The invention particularly aims to provide an efficient vacuum device and method for the manufacturing of composite parts.

The invention aims to provide a vacuum device and method which provide composite parts of high quality.

The invention aims to provide a vacuum device and method with improved effectiveness.

The invention also aims to provide an economical device.

The invention proposes a device for the manufacturing of composite parts as defined in claim <NUM>.

In the whole text, the term 'vacuum' is used in relation to a lower pressure than an ambient pressure where the device according to the invention is placed. In particular, in usual condition, the device will be at atmospheric pressure, and a vacuum will be a very low pressure compared to atmospheric pressure, such as for example a pressure of between <NUM> and <NUM> milliBars.

The vacuum film (also sometimes called `vacuum bag') is an airtight film adapted to be sealed to the support with a seal so as to form an airtight chamber. The vacuum film transmit a pressure differential between its outer face and its inner face to composite parts placed in the vacuum chamber when vacuum is applied in the vacuum chamber.

The seal may be adapted for sealing a periphery of the vacuum film to the support so as to form an airtight chamber.

The vacuum distribution device is placed between the support and the vacuum film, in the vacuum chamber. The vacuum distribution device is adapted to, at least locally, maintain the vacuum film at a predetermined distance from the support.

The vacuum distribution device comprises a distribution base adapted to be hydraulically connected to the vacuum port.

More particularly, the distribution base is adapted to be hydraulically connected to the hydraulic connection of the vacuum port.

The distribution base may comprise at least three distribution ports. Each distribution port is adapted to be hydraulically connected to the vacuum port through at least one channel in the distribution base.

Each distribution port is hydraulically connected to the hydraulic connection of the vacuum port.

The distribution base may comprise one or two distribution ports. The inventors have determined that at least three distribution ports, for example four distribution ports may be beneficial in some embodiments. The distribution base may have more than four distribution ports.

The distribution ports open between the vacuum film and the support.

The distribution base may be adapted to form a mechanical keyed connection with the vacuum port, at least when a vacuum is applied through the vacuum port.

When a vacuum is applied through the vacuum port, the vacuum port is brought towards the support. The distribution is placed between the vacuum port and the support. The vacuum port and the distribution base engage in a keyed connection when the vacuum port is maintained against the distribution port.

The keyed connection is particularly adapted to avoid a relative rotation between the distribution base and the vacuum port. This allows to avoid the formation of crease on the vacuum film, part of which is pinched in between the vacuum port and the distribution base, in particular when vacuum is applied. By having few or no creases on the vacuum film a homogeneous pressure is applied on the composite part and a better vacuum is obtained.

The keyed connection avoids that creases form on the vacuum layer when the vacuum port is connected, in particular when the vacuum port must be connected by a rotational movement. In particular, creases are avoided because the distribution base and the vacuum port do no need relative attachment such as screwing.

At least a first of the vacuum port and the distribution base may comprise at least one groove and a second of the vacuum port and the distribution base may comprise at least one complementary rib.

The vacuum port and the distribution base comprise complementary shapes. In particular at least a first of the vacuum port and the distribution base may comprise one or more groove and a second of the vacuum port and the distribution base may comprise one or more rib complementary for being engaged with a groove of the first of the vacuum port and the distribution base. In some embodiment the distribution base comprises a plurality of ribs on a face arranged to be placed toward the vacuum port, and the vacuum port comprises complementary grooves on a face arranged to be placed toward the distribution base.

The vacuum distribution device comprises at least two elongated distribution branches.

Said distribution branches are adapted to distribute the vacuum at one or more points, distant from the distribution base, so as to reach areas of the vacuum chamber that are remote from the distribution base and vacuum port. The number of vacuum ports may thus be limited, while reaching a homogeneous vacuum in the vacuum chamber.

The distribution branches comprise a distribution conduit along at least part of its length.

The distribution conduit may be arranged to be hydraulically connected to a distribution port of the distribution base.

The distribution port may be an opening with a shape and size adapted to receive an end of the distribution branch.

The distribution port may be used with or without a distribution branch attached to it. The distribution base may be used with a lower number of distribution branches than its number of distribution ports. Thereby the configuration of the vacuum table may be adapted depending on where the distribution base is placed and depending on the size and shape of the composite part.

The distribution branches comprise one or more suction ports along its length.

The distribution of the suction ports along the distribution branch may be chosen according to a predetermined pattern. The pattern may vary based on the composite parts to be manufactured.

The envelope of the distribution conduit may intersect at least one face of the distribution branch at one or more section of said face, so as to form suction port(s).

The distribution conduit may be open on its entire length on a face of the distribution branch so as to form an elongated suction port.

The vacuum may thus be distributed along the whole length of the distribution branch. Besides, the manufacturing of such distribution branch may be particularly cheap. The distribution branch may be a profile part. In particular, the distribution branch may have a constant cross-section.

The distribution branches may be extruded components.

A device according to the invention may further comprise at least two distribution bases, and at least one distribution branch, said distribution branch comprising a first end hydraulically connected to a first distribution base, and a second end hydraulically connected to a second distribution base.

The distribution branches comprise a distribution conduit open to the first end of the distribution branch and to the second end of the distribution branch such that the two distribution bases are in fluid connection.

A device according to the invention may further comprise a breathing layer arranged between the vacuum film and the support, with the distribution device arranged between the vacuum film and the breathing layer.

The invention also extends to a method for applying pressure to a composite part, as defined in claim <NUM>.

Said breathing layer may be adapted to provide a fluid connection both transversally and longitudinally to its thickness.

More particularly the breathing layer is arranged between the composite part and the vacuum film.

In such method, a breathing layer may be arranged between the composite part and the vacuum film, and the distribution device may be arranged between the breathing layer and the vacuum film. The distribution device may be placed between the breathing layer and the vacuum film in areas where there is no composite part.

In a method according to an embodiment of the invention, a vacuum source is connected to the vacuum port. Upon activation of the vacuum source, the gases contained between the vacuum film and the support are sucked up the distribution device, the vacuum port and the vacuum source.

Some specific exemplary embodiments and aspects of the invention are described in the following description in reference to the accompanying figures.

In <FIG>, a sub-assembly of a device according to the invention is represented. It comprises a vacuum distribution device <NUM> and a vacuum port <NUM>.

The vacuum port <NUM> comprises a body <NUM> with a connector <NUM> adapted for being connected to a vacuum pipe <NUM> (not represented on this figure). The vacuum port <NUM> further comprises a external clamp <NUM> for being placed on the external side of a vacuum film <NUM> (not represented on this figure). It also comprises a internal clamp <NUM> for being placed on the internal side of a vacuum film <NUM>. The body <NUM>, the clamps <NUM>, <NUM> and the connector <NUM> of the vacuum port <NUM> are all adapted to form a fluid connection between a vacuum pipe <NUM> and the internal side of a vacuum film <NUM> when assembled together as represented on <FIG>. In particular the body, and the clamps <NUM>, <NUM> comprise at least one vacuum conduit.

The vacuum distribution device <NUM> comprises a distribution base <NUM> and a distribution branch <NUM>.

In this embodiment, the distribution base <NUM> comprises four distribution ports <NUM> as may also be seen on <FIG>. The distribution base is adapted to provide a fluid connection between a port <NUM> on its upper face <NUM> and the distribution ports <NUM>. The upper face <NUM>, represented on <FIG>, is adapted to be connected with the internal clamp <NUM> of the vacuum port <NUM> so as to ensure a fluid connection between the port <NUM> of the distribution base <NUM> and the vacuum pipe <NUM> through the vacuum port <NUM>.

As can be seen on <FIG>, the distribution branch <NUM> and the distribution ports <NUM> have complementary shapes such that an end of the distribution branch <NUM> may fit in the distribution port <NUM> of the distribution base <NUM>. In this embodiment, the distribution branch <NUM> has a constant cross-section. The distribution branch <NUM> may be obtained by extrusion. The distribution branch <NUM> comprises a distribution conduit <NUM> all along its length. In the embodiment presented in <FIG>, the distribution conduit <NUM> is so that is open on its whole length on a face of the distribution branch <NUM>. The distribution conduit <NUM> is open on a face, later referred as lower face, of the distribution branch <NUM> adapted to be placed against a breathing layer <NUM> as may be seen on <FIG>. A distribution device <NUM> according to the invention, and in particular the distribution branch <NUM>, ensures a function of distributing the vacuum along its length under the vacuum film, such that the vacuum is not applied at the one or more punctual locations of the vacuum ports, but rather along distributed lines. The distribution branch provides an elongated suction port.

With the distribution branch <NUM> mounted with one end in a distribution port <NUM> of the distribution base <NUM> as shown on <FIG>, the distribution conduit <NUM> opens at one end of the distribution branch <NUM> into the distribution port <NUM> of the distribution base <NUM> such that the distribution conduit <NUM> provides a fluid connection between the elongated suction port that its distribution conduit <NUM> form along the lower face of the distribution branch and the distribution port <NUM> of the distribution base <NUM>.

The distribution branch <NUM> has a substantially triangular external cross-section. The lower face of the distribution branch <NUM> is generally flat, except for the opening of the distribution conduit <NUM>. However, in some other embodiments, the lower face of the distribution branch <NUM> may not be flat, for example it may be corrugated. The upper side of the distribution branch <NUM> form a rounded transition from one of its side face to the other of its side face, so as to not damage the vacuum film <NUM> which will be applied against the distribution branch <NUM> upon application of vacuum at the vacuum port <NUM>.

In this embodiment, the upper face <NUM> of the distribution base <NUM> is generally round, as represented on <FIG>. It comprises a hole acting as a port <NUM> in its center for connecting the distribution ports <NUM> to the vacuum port <NUM>. The upper face <NUM> comprises three radial ribs <NUM>. <FIG> also shows the lower face of the internal clamp <NUM> of the vacuum port <NUM>. The internal clamp <NUM> has a round shape and comprises a hole <NUM> in its middle for connecting the port <NUM> of the distribution base to the vacuum conduit in the body <NUM> of the vacuum port <NUM>. The internal clamp <NUM> and the distribution base <NUM> are adapted to be assembled together so that the hole <NUM> of the internal clamp <NUM> and the port <NUM> of the distribution base <NUM> are and remain aligned when assembled, and in particular when vacuum is applied. To ensure the centering of the internal clamp <NUM> on the distribution base <NUM>, the lower face of the internal clamp <NUM> comprises three radial grooves <NUM> complementary to the radial ribs <NUM> of the upper face <NUM> of the distribution base <NUM>. The relative rotation of the internal clamp <NUM> and the distribution base <NUM> is also prohibited by this rib and groove assembly, in particular under application of vacuum which tends to press the internal clamp <NUM> against the distribution base <NUM>.

In <FIG> a detail of the vacuum port <NUM> is represented with the body <NUM> and external clamp <NUM> on one side and the internal clamp <NUM> seen from above on the other side. The external clamp <NUM> and the internal clamp <NUM> are adapted to clamp a vacuum film <NUM> between them, as can be seen on <FIG>.

The upper face of the internal clamp <NUM> comprises concentric grooves and ribs <NUM> around its central hole <NUM>, so as to avoid a relative displacement between the external clamp <NUM> and the internal clamp <NUM>. Indeed a relative movement of the external clamp <NUM> and the internal clamp <NUM> may induce creases on the vacuum film which may in turn lead to a lower vacuum quality under the vacuum film <NUM> or to a non-homogeneous pressure on the composite part under the vacuum film. The external clamp <NUM> and internal clamp <NUM> are thus locked when pressed against each other upon application of vacuum, such that no crease may form on the vacuum film clamped between them. The lower face (not represented) of the external clamp <NUM> may comprise grooves and ribs complementary to those of the upper face of the internal clamp <NUM>. In other embodiments, the external clamp <NUM> and internal clamp <NUM> may also comprise complementary radial ribs and/or grooves respectively on their lower face and upper face.

In <FIG> a complete vacuum device <NUM> according to an embodiment of the invention is represented. Such device is also sometimes called vacuum table. A detail of the device is shown on <FIG> , such that both figures will be described concurrently in the following text.

The device <NUM> comprises an airtight support <NUM>, an airtight vacuum film <NUM> placed over the support <NUM>, and an airtight seal <NUM> running all around the periphery of the support <NUM> and vacuum film <NUM> so as to airtightly seal the vacuum film to the support <NUM>. In between the vacuum film <NUM> and the support <NUM>, a breathing layer <NUM> is placed. The breathing layer ensures a distribution of vacuum along its whole surface by allowing air and other gases to circulate between it fibers, while the fibers maintain a minimum distance between the vacuum film <NUM> and the support <NUM>.

The device further comprises vacuum ports <NUM> - in this embodiment two vacuum ports <NUM> - connected to vacuum pipes <NUM> on one side and on the other side to vacuum distribution devices <NUM>. The vacuum pipes are connected to a vacuum source.

The vacuum ports <NUM> and vacuum distribution devices may be of the type presented in relation to <FIG>. The distribution device <NUM> most at the forefront of <FIG> comprises two distribution branches <NUM> connected to two different distribution ports of a distribution base. In this embodiment, some distribution branches <NUM> are connected by a first end to a distribution device <NUM> connected to a vacuum port <NUM>, and by a second end to a connector <NUM> which is not connected to a vacuum port, and only acts as a connector <NUM> between two distribution branches <NUM> so as to form angles along the suction port provided by the distribution branches <NUM>. The connector <NUM> may be obtained by using a distribution base <NUM> of a distribution device <NUM>. A distribution branch <NUM> may, as shown on <FIG> be installed between two connectors <NUM>.

The distribution devices <NUM>, including the distribution base <NUM> and distribution branches <NUM> are installed between the breathing layer <NUM> and the vacuum film <NUM>. The distribution branches <NUM> comprise distribution conduits <NUM> similar to those presented in relation to <FIG>, such that an elongated suction port is provided along a linear profile on the breathing layer. This distribution of the suction port along one or more lines on the breathing layer improves significantly the vacuum attained by a device according the invention.

In this embodiment of a device <NUM> according to the invention, only one vacuum port <NUM> is used. The risk and amount of vacuum leaks due to vacuum ports is thereby also limited. Thanks to the distribution devices <NUM> according to the invention, the vacuum port <NUM> provides a vacuum as good as or better than the vacuum obtained with six vacuum ports when no distribution devices according to the invention are used. Therefore in a device according to the invention, the manufacturing of composite parts is simplified and made cheaper. The manufacturing is also of a better quality, because a limited number of crossings of the vacuum film <NUM> by vacuum ports <NUM> allows to have less vacuum leaks and less creases on the vacuum film.

The device <NUM> also comprises a vacuum sensor <NUM> for measuring the vacuum attained in the vacuum chamber <NUM> formed between the vacuum film <NUM> and the support <NUM>.

In <FIG>, a cross-section of a device of the type presented in relation to <FIG> is represented. It shows a composite part <NUM> placed on a support <NUM>. The device comprises a seal <NUM> around the periphery of the support <NUM>. A breathing layer <NUM> is arranged over the composite part <NUM> and support <NUM>. A vacuum film <NUM> is arranged over the breathing layer <NUM> and is sealed to the support <NUM> by the peripheral seal <NUM>. Between the breathing layer <NUM> and the vacuum film <NUM> a distribution base <NUM> and a distribution branch <NUM> may be seen on the left side of the composite part, while a distribution branch may be seen on the right side of the composite parts. All distribution branches are directly, or indirectly through a connector <NUM> hydraulically connected to a distribution base and a vacuum port. The distribution base <NUM> is connected to a vacuum port <NUM>, itself connected to a vacuum pipe <NUM>.

The breathing layer allows an air and gas circulation in all parts of a vacuum chamber <NUM> formed by the airtight support <NUM>, the airtight seal <NUM> and the airtight vacuum film <NUM>. In particular the breathing layer allows an air and gas circulation from the composite part towards the distribution conduits <NUM> of the distribution branches. The proximity and length of the distribution conduits <NUM> to the composite parts allow a good vacuum distribution in the vacuum chamber <NUM>.

In <FIG>, steps of a method of manufacturing according to an embodiment of the invention are represented.

In a first step <NUM>, one or more composite parts <NUM> are placed on an airtight support <NUM>.

In a second step <NUM>, a seal is arranged at the periphery of the support <NUM>.

In a third step <NUM>, a breathing layer <NUM> is arranged over the composite parts <NUM> and support <NUM>.

In a fourth step <NUM>, one or more distribution devices <NUM> are arranged on the breathing layer. In particular, at least one distribution base <NUM> and one or more distribution branches <NUM> are arranged on the breathing layer. The distribution devices <NUM> may be arranged on the breathing layer avoiding the areas of the breathing layer directly over the composite parts <NUM>.

In a fifth step <NUM>, a vacuum film <NUM> is arranged over the breathing layer <NUM> and the seal <NUM>.

In a sixth step <NUM>, the vacuum film <NUM> is sealed to the support <NUM> with the seal <NUM>, for example by applying pressure to the film <NUM> along the seal <NUM>, so as to form and airtight chamber between the support <NUM>, the seal <NUM> and the vacuum film <NUM>.

In a seventh step <NUM>, a vacuum port <NUM> is hydraulically connected to each distribution device <NUM>, in particular to each distribution base <NUM>. The vacuum film <NUM> may be opened at this step between the vacuum port and the distribution base, so as to cross the vacuum film <NUM>. The vacuum film may alternatively be opened in advance at the locations of the vacuum ports. The internal clamp of the vacuum port may also be placed on the distribution base before the step <NUM>, so that this clamp is already on the internal face of the vacuum film.

Claim 1:
Device (<NUM>) for the manufacturing of composite parts (<NUM>) comprising:
- an airtight support (<NUM>) for supporting one or more composite parts (<NUM>),
- an airtight vacuum film (<NUM>),
- at least one vacuum port (<NUM>) adapted to provide a hydraulic connection between a first face of the vacuum film (<NUM>) and a second face of the vacuum film (<NUM>),
- an airtight seal (<NUM>) for sealing at least a portion of the vacuum film (<NUM>) to the support (<NUM>) so as to form an airtight chamber (<NUM>),
- a vacuum distribution device (<NUM>):
∘ adapted to be hydraulically connected to the vacuum port (<NUM>) and placed between the support (<NUM>) and the vacuum film (<NUM>),
∘ comprising a distribution base (<NUM>) adapted to be hydraulically connected to the vacuum port (<NUM>),
iaracterized in that the vacuum distribution device (<NUM>) further comprises:
- at least two elongated distribution branches (<NUM>),
- a connector (<NUM>) which is not connected to a vacuum port, for hydraulically connecting two distribution branches (<NUM>).