Vacuum press device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN AEROSPACE COMPOSITES
- Filing Date
- 2023-08-18
- Publication Date
- 2026-06-24
AI Technical Summary
Existing vacuum press devices are not efficient in removing trapped air from prepreg plies, leading to porosity in the final cured material, which weakens the structure and reduces its quality.
A vacuum press device with a vacuum distribution pad comprising a first and second porous anti-adhesive sheet and a stack of breather mesh layers, which evenly distributes vacuum pressure to improve compaction and reduce porosity.
The improved vacuum distribution pad ensures even vacuum pressure distribution, enhancing the compaction of prepreg plies and reducing the risk of porosity, thus producing higher-quality composite structures.
Smart Images
Figure US2023030621_27022025_PF_FP_ABST
Abstract
Description
TITLE : VACUUM PRESS DEVICEField of the invention
[0001] The present invention relates to a vacuum press device and a process for the compaction of a product.Background of the invention
[0002] It is known to use a vacuum press device, comprising at least: a support having a first element; a cover that is movable between a first position in which it is applied onto the first element, and a second position in which it is remote from the first element; at least one vacuum source connected to at least one vacuum port of said support; and a control unit connected to the at least one vacuum source and configured to actuate a vacuum between the first element and the cover when the cover is in its second position.
[0003] Such a device is for example a debulking table configured for compacting a product such as for example, and without limitation, a stack of prepreg plies. Prepregs are serving as the basic building block to fabricate high-performance composite structures used for example in the fields of automotive, aerospace, etc. Prepregs are laminate composites of fiber sheets that are impregnated with resins that have not been fully cured. Fiber sheets are often made of glass fibers, carbon fibers, or polyaramid (Kevlar) fibers.
[0004] Prepregs may be made by creating layered soft and flexible sheets or plies of materials.
[0005] The layering of plies can leave air trapped between the layers of plies of the prepreg materials. If this air is not removed before the curing process of the material, it may create defaults such as for example porosity in the final cured material or part. These defaults may weaken the structure made from the defect prepregs or reduce its quality.
[0006] A vacuum press device as described above is used to remove such trapped air. However, the debulking or compaction process applied with such device on the prepregs plies is often not efficient for removing all the trapped air.
[0007] It may be desired to provide a vacuum press device where the compaction of product such as prepregs plies is improved.Summary of the invention
[0008] To this end, it is proposed a vacuum press device, the vacuum press device comprising at least : a support having a first element; a cover that is movable between a first position in which it is applied onto the first element, and a second position in which it is remote from the first element; at least one vacuum source connected to at least one vacuum port of said support; and a control unit connected to the vacuum source and configured to actuate a vacuum between the first element and the cover when the cover is in its second position ; wherein the vacuum press device further comprises: a vacuum distribution pad comprising at least:• a first porous and anti-adhesive sheet having a peripheral edge ;• a stack of layers of breather mesh disposed on top of the first porous sheet; and• a second porous and anti-adhesive sheet disposed on top of the stack of layers of breather mesh; said second and anti-adhesive porous sheet having a peripheral edge; and the peripheral edges of the first and second porous and anti-adhesive sheets being connected one another so as to embed the stack of layers between the first and second porous and anti-adhesive sheets ; said vacuum distribution pad laying onto the first element so that : the first porous and anti-adhesive sheet comprises a lower face applied onto an upper face of the first element and covering said at least one vacuum port, and the second porous and anti-adhesive sheet comprises an upper face which faces a lower face of the cover when the cover is in its second position, said upper face of said second porous and anti-adhesive sheet and said lower face of said cover being suitable to sandwich a product to be compacted.
[0009] According to the invention, a porous sheet is a sheet of a material containing void space(s) or pore(s) in which fluids (for example gas, air, ...) may be absorbed or discharged.
[0010] According to the invention, an anti-adhesive sheet is a sheet that prevents adhesion.
[0011] According to the invention, a stack of layers of breather mesh is a pile of layers of a porous material that allow air to flow away from a product being pressed and towards a vacuum port for example.
[0012] According to the invention, prepregs or prepreg plies are laminate composites of fiber sheets that are impregnated with resins that have not been fully cured. Fiber sheets are often made of glass fibers, carbon fibers, or polyaramid (Kevlar) fibers. The prepregs may be in the form of a stack of sheets.
[0013] It has been found by the inventors that the lack of compacting force on some portions of a product such as a stack of plies or prepreg plies, was causing the porosity between the plies after a curing process. The inventors also found out that this lack of compacting force was due to a non-uniform distribution of the vacuum pressure inside the vacuum press device. The second porous and anti-adhesive sheet allows the air to flow inside the pad and provides a non-adherent surface for the stack. The inventor also found out that the structure of the vacuum distribution pad, as described in the present application, makes it possible to evenly distribute the vacuum pressure on the surface of the first element. Consequently, the improve of the compaction of a stack of plies is improved and the risk of occurrence of porosities is reduced. Thus, the vacuum press device as described in the present application may be suitable, for example, for the debulking of prepreg plies prior to a curing process.
[0014] Moreover, the vacuum pad of the invention does not need to be replaced between applications and may be reused multiple times. This allows to reduce the ecological footprint, while allowing a gain in energy and material resources by reducing, for example, the manufacture or the maintenance of a stack or prepreg plies.
[0015] Some further optional features of the vacuum device according to the invention which can be used together or separately are listed below: the stack of layers of breather mesh comprises at least two layers; the first and second and anti-adhesive sheets are made of PTFE;the peripheral edges of the first and second porous and anti-adhesive sheets are connected together by a flexible tape; the flexible tape is made of PTFE; the first element forms an angle between 0 and 90° with respect to a horizontal plane; the support comprises at least one vacuum port provided on at least one side of said support and communicating with the vacuum port on the first element; the vacuum press device comprises a plurality of vacuum sources and / or a plurality of vacuum ports, the vacuum ports being uniformly distributed on the first element and / or on at least one side of the support; the support is a table; the first element is a plate; the cover is a plate;
[0016] The invention also relates to a system comprising: the vacuum press device as described in the present invention; and a stack or prepreg plies which is sandwiched between said upper face of said second porous and anti-adhesive sheet and said lower face of said cover.
[0017] The invention also relates to a method for compacting a stack or prepreg plies, the method comprising at least the following steps: positioning a stack or prepreg plies in a vacuum press device as described in the present application, said stack or prepreg plies being sandwiched between said upper face of said second porous and anti-adhesive sheet and said lower face of said cover; and actuating the vacuum source so as to compact the stack or prepreg plies
[0018] Some further optional features of the method according to the invention which can be used together or separately are developed below: a) positioning the stack or prepreg plies in the vacuum press device on to the vacuum pad; b) compacting the stack or prepreg plies; c) removing the compacted stack or prepreg plies from the vacuum pad; d) positioning another stack or prepreg plies in the vacuum press device on top of the vacuum pad;e) repeating the steps b), c) and d)Brief description of the drawings
[0019] The present invention will be described more specifically with reference to the following drawings, in which: figure 1 is a perspective view showing an example of a vacuum press device according to the prior art; figure 2 is another perspective view of the vacuum press device of figure 1 according to the prior art; figure 3 is a perspective view showing an example of a vacuum press device according the invention; figure 4 is a schematic view of a vacuum distribution pad according the invention, figure 5 is a schematic cross-section view of a portion of the vacuum press device of figure 3, in which a product in positioned; and figure 6 is a schematic view of a process for compacting a product according the invention.Detailed description of the preferred embodiments
[0020] Referring to figure 1 , an example of vacuum press device 100 as found in the prior art will now be described. The vacuum press device 100 is for example, and without limitation, a debulking table or any device that needs to apply vacuum to a surface.
[0021] The vacuum press device 100 comprises a support 102. In this example, the support 102 is, without limitation, a table as for the other figures (figures 1-5) of the present application representing the vacuum press device 100.
[0022] The support 102 may comprise at least a base 103 and legs 122 fixed to the base 103. The support 102 may further includes a first element 104 that is in general horizontal and fixed on top of the base 103. The first element 104 comprises an upper face S101 configured for bearing at least a product or a stack of plies of a product such as for example, and without limitation, prepreg plies of a composite material.
[0023] The Vacuum press device may further comprise a cover 106. The cover may be a part of the support 102 and therefore, considered as a second element of the support 102. The cover 106 is movable between a first position PQ in which it is applied onto the first element 104, and a second position Pi in which it is remote from the first element 104. Figure 1 illustrates the vacuum press device wherein the cover 106 is in the second position P-i. A situation wherein the cover 106 is in the first position Po is illustrated for example in figure 2.
[0024] The cover 106 is fixed or mounted at one end of the base 103. More precisely, the cover 106 is pivotally fixed or mounted relative to the base 103 or the first element 104. As illustrated on Figure 1 or figure 2, the support 102 may comprise a pivot axis A parallel to the junction between the cover 106 and the base 103 of the support 102. The cover 106 comprises a lower face S102 facing the upper face S101 of the first element 104.
[0025] In some embodiments, the vacuum press device may comprise a metal plate or a silicone membrane disposed on top of the first elementl 04 of the support 102.
[0026] Still referring to figure 1 , the vacuum press device 100 may further comprise a vacuum source 110 including at least a pipe 112 for connecting the vacuum source 110 to the support 102. The vacuum source 110 is configured for applying a vacuum pressure on the upper surface of the first element 104 facing the cover 106. To this aim, the first element 104 may comprise vacuum port 108 to which an extremity of the pipe 112 of the vacuum source 110 may be connected.
[0027] The support 102, may also comprise a third element 116 disposed under the first element 104 and configured to receive the vacuum source 110. The third element may be a plate. The third element 116 is fixed or related to the legs 122 of the support 102.
[0028] The vacuum device 100 further comprises a control unit 114 that may be connected to the vacuum source 110. The control unit 1 14 is configured to actuate a vacuum between the first and covers when the cover is in its second position Pi, that is when it is remote from the first element 104.
[0029] The vacuum source 110 is thus used to apply vacuum on the stack or product 1 by evacuating the air out the encased stack or product.
[0030] When the vacuum pressure has been applied, the cover is moved from the second position P-i to the first position Po so as to compact the stack of plies or product.
[0031] In some embodiments, the vacuum press device 100 may further comprise a vacuum bag 2 (see figure 4), for example and without limitation a silicone membrane, configured to be placed on top of the product 1 or a stack of plies of the product before applying vacuum pressure.
[0032] The vacuum press device 100 may also comprise a flexible sealant material 3 (see figure 4) used to seal the vacuum bag 2 to the support 102 or a tooling on which the stack of plies or the product 1 may be disposed.
[0033] Referring to figure 3, a vacuum press device according to the present invention is described. The vacuum press device 100 of the present invention includes at least all the above-mentioned features.
[0034] Thus, the vacuum press device 100 comprises at least: a support 102, which may be for example, and without limitation, a table comprising a base 103, legs 122 which are fixed to the base 103.
[0035] The support 102 comprises a first element 104 positioned or mounted on top of the base 103; a cover 106 pivotally mounted about a rotation axis A relative to the base 103 or the first element 104 and moving between a first position Po in which it is applied onto the first element 104, and a second position Pi in which it is remote from the first element 104.
[0036] The first element 102 forms an angle between 0 and 90° with respect to a horizontal plane. Preferably, the first element is horizontal, that is to say parallel to the horizontal plane.
[0037] In a variant, the angle is preferably between 0 and 45° and preferably 30°.
[0038] The first element may also be flat or have a curved shape or a complex shape depending on the type of shape required for the structure to be produced from the stack or product to be compacted. For example, and without limitation, the structure may be an annular component, such as a carter of an airplane. In this example, the first element may be flat or curved.
[0039] The support 100 may also comprise a third element 116, fixed or related to the legs 122 and, disposed under the first element104 and configured to receive at least one vacuum source 110. The third element is preferably a plate. The at least one vacuum source is connected to at least one vacuum port of the support 102.
[0040] The at least one vacuum port 108 is provided on the first element.
[0041] The support may also comprise at least one vacuum port provided on at least one side of said support and communicating with the vacuum port disposed on the first element 104.
[0042] The vacuum press device 100 may further comprise a control unit 1 14 connected to the vacuum source 110 and configured to actuate a vacuum between the first element 104 and the cover 106 when the cover 106 is in its second position P< a vacuum bag 2 to cover the product to be compacted, a flexible sealant material 3 used to seal the bag 2.
[0043] In some embodiments, the vacuum press device 100 may comprise a plurality of vacuum sources and / or a plurality of vacuum ports. The vacuum ports may be uniformly distributed on the first element 104 and / or on at least one side of the support so as to improve the compaction of the product.
[0044] In another embodiment (not represented), the support 102 comprises the above-mentioned features, wherein the base 103 includes a housing configured for fixing or mounting the first element. In this case, the first element 104 may also be configured to be mounted or fixed by interlocking in the provided housing of the base 103. Thus, depending on the application and the type of shape of the stack or product, the appropriate first element (with a flat, curved or complex shape) may be chosen and fixed or mounted on the base 103.
[0045] Therefore, those skilled in the art should understand that the vacuum press device 100 may be in the form of a kit comprising at least the above-mentioned features.
[0046] In addition to the previously described features, the vacuum press device of the present invention further includes a vacuum distribution pad 120, laying onto the first element 104.
[0047] The vacuum distribution pad 120, as illustrated in figure 4, has a parallelepipedal shape. The vacuum distribution pad 120 comprises a first porous and anti-adhesive sheet having a peripheral edge PEi. The peripheral edge PE-, comprises two short sides and two long sides (compared to said short sides). The first porous sheet may be for example, and without limitation, made of polytetrafluoroethylene (PTFE) The first porous sheet has a thickness between 20pm and 30pm, preferably 25pm.
[0048] The first porous and anti-adhesive sheet 200i comprises a lower face S201 applied onto the upper face S101 of the first element 104 and covering an opening of the at least one vacuum port.
[0049] The vacuum distribution pad 120 further comprises a stack of layers of breather mesh 204 disposed on top of the first porous sheet 200i . The stack of layers of breather mesh 204 comprises at least two layers. In the example illustrated by figure 4, the stack of layers comprises two layers 204.
[0050] In some embodiments, the stack of breather mesh 204 may comprises a plurality of layers. As mentioned above, a breather mesh is a porous material that allows air to flow away from a product being pressed and towards a vacuum port. The material may be natural fibers, metal mesh or any other substrate that allows a fluid to flow through it without resistance. Preferably, each breather mesh has a thickness around 25pm.
[0051] In some embodiments, the number of breather mesh layers may be increased so as to improve the distribution of vacuum pressure in the vacuum press device 100. Therefore, the vacuum distribution pad 120 may comprise more than two layers of breather mesh 204.
[0052] The vacuum distribution pad 120 further comprises a second porous antiadhesive sheet 2OO2 disposed on top of the stack of layers of breather mesh 204. Similarly to the first porous sheet 200-,, the second and anti-adhesive porous sheet has also a peripheral edge PE2. The second porous sheet has a thickness between 20pm and 30pm, preferably 25pm.
[0053] The second porous and anti-adhesive sheet 2OO2 comprises an upper face S202 which faces the lower face S102 of the cover 106 of the support 102 when the cover 106 is in its second position Pi. The upper face S202Of the second porous and anti-adhesive sheet 2OO2 and the lower face Sio20f the cover 102 are suitable to sandwich a product, for example a stack of prepreg plies, to be compacted. The second porous sheet 2OO2 may also be for example, and without limitation, made of PTFE.
[0054] The peripheral edge PE1, PE2, respectively of the first and second porous sheets 200i , 2OO2 are connected one to another so as to embed the stack of layers 204 between the first 200i and second 2OO2 porous and anti-adhesive sheets.
[0055] The peripheral edges PE1, PE2, of the first and second and anti-adhesive sheets 200i, 2OO2 may be connected by a tape 202. Preferably, the tape is flexible so that thevacuum distribution pad 120 can expand and compress during the compaction of the product.
[0056] The tape 202 may further comprise an anti-adhesive surface. Like the first and second porous sheets 200i, 2002, the tape 202 may also be for example, and without limitation, made of PTFE.
[0057] Figure 5 shows an example of a disposition of a product 1 in the vacuum device 100. The product 1 is positioned onto the vacuum distribution pad 120 prior to the compaction. In this example, a vacuum bag 2 is used to cover the product 1 and the vacuum bag is sealed to the first element 104, which in this example is a plate, by a sealant material or tape 3. The internal surface SVb of the vacuum bag 2 and the external surface of the S101 of the first element define a volume Vo which contains air which must be evacuated through the vacuum port 108 of the first element 200i by means of the vacuum source 110 (air flow F in figure 4).
[0058] The weight of the product constrains the second porous and anti-adhesive sheet 2OO2 which in turn constrains the stack of layers of breather mesh 204. The constraint exerted by the weight of the product is evenly distributed over the surface S202 of the second porous and anti-adhesive sheet 2OO2. Thus, when the air is evacuated from the volume Vo, through the vacuum port 108, the vacuum pressure P generated by the evacuation of the air will evenly apply on an upper surface So of the product facing the internal surface SVb of the vacuum bag 2.
[0059] The air flow F passes through the second sheet 2OO2 which is porous. The air flow F is evenly evacuated, by the layers of breather mesh 204, through the vacuum distribution pad 120 due to the evenly applied constraint. Since the first porous and anti-adhesive sheet 200i is also porous, the air flow F is evenly evacuated on the surface portion of the first element on which the vacuum pad is positioned. In other words, the pressure is uniformly or evenly distributed over the surface of the first element 104.
[0060] The vacuum pad may be configured to support a maximum vacuum pressure around 1 bar, preferably 1 bar.
[0061] Advantageously, it should be understood that in the case wherein the product is a stack of plies, such as for example a stack of prepreg plies, the vacuum pressure on the stack will evenly evacuate the air located between the plies in such a way that after compaction, no air will remain trapped in an area between the plies. Therefore,the compaction of the product is improved using the vacuum press device 100 as described in the present application.
[0062] A better compacted stack or prepreg plies will have a lower chance to present trapped air between plies prior to a curing process for example. Consequently, this will prevent the cured material to present for example voids or porosities. Therefore, advantageously, the vacuum press device 100 also prevents defaults such as those mentioned above after a curing process.
[0063] Moreover, since the surface S202 of the second porous sheet 200? is antiadhesive, a resin cannot adhere to the vacuum distribution pad 120. Therefore, it should be understood that the vacuum distribution pad 120 as described in the present application may be reused multiple times. This means that the present vacuum press device 100 has an advantage of reducing ecological footprint while allowing a gain in energy and material resources by reducing, for example, the manufacture or the maintenance of a stack or prepreg plies.
[0064] Indeed, the maintenance of devices or parts of a device, such as for example a turbomachine, made from a product, a stack or prepreg plies compacted with the vacuum press device as described in the present application is improved. Thus, the compaction as described reduced the risk of defaults and consequently the maintenance of the devices of parts of the device.
[0065] Referring to figure 6, the invention also comprises a method for compacting a stack or prepreg plies by using the vacuum press device as described in the present application.
[0066] The method comprises at least a step 400 of positioning a stack or prepreg plies in a vacuum press device. The stack 1 or prepreg plies are disposed on the vacuum distribution pad, more precisely on top of the upper face of the second porous and anti-adhesive sheet 200?. As mentioned above, the stack or prepreg plies are covered by a vacuum bag 2 and sealed to the first element by a sealant tape 3, as illustrated in figure 4. The stack 1 or prepreg plies, covered by the bag 2, are sandwiched between the upper face of the second porous and anti-adhesive sheet 2OO2 and the lower face S102 of the cover 106 of the support 102.
[0067] The method further comprises actuating the vacuum source 110 so as to compact the stack or prepreg plies using the control unit 114 connected to the vacuum source 110. In this stage, after the actuation of the vacuum source and the applicationof the vacuum pressure, the cover is moved from the second position Pi to the first position Po so as to compact the stack of plies or product.
[0068] In some embodiments, the method may further comprise at least the following steps: a) positioning the stack or prepreg plies in the vacuum press device on to the vacuum distribution pad; b) compacting the stack or prepreg plies; c) removing the compacted stack or prepreg plies from the vacuum pad; d) positioning another stack or prepreg plies in the vacuum press device on top of the vacuum distribution pad; e) repeating steps b), c) and d)
[0069] The vacuum pad may be removed from the first element 104 between applications or stay in position on the first element 104.
Claims
CLAIMS[1] A vacuum press device (100), the vacuum press device (100) comprising at least: a support (102) having a first element (104); a cover (106) that is movable between a first position (P0 in which it is remote from the first element (104), and a second position (P2) in which it is applied onto the surface (104); at least one vacuum source (110) connected to at least one vacuum port (108) of said first element (104); and a control unit (1 14) connected to the at least one vacuum source (110) and configured to actuate a vacuum between the first element (104) and the cover (106) when the cover (106) is in its second position (P2); wherein the vacuum press device (100) further comprises: a vacuum distribution pad (120) comprising at least:• a first porous and anti-adhesive sheet (200i) having a peripheral edge (PEO ;• a stack of layers of breather mesh (204) disposed on top of the first porous sheet (200i); and• a second porous and anti-adhesive sheet (2002) disposed on top of the stack of layers of breather mesh (204); said second and anti-adhesive porous sheet (2002) having a peripheral edge (PE2); and the peripheral edges of the first and second porous and anti-adhesive sheets (200i, 2002) being connected one another so as to embed the stack of layers (204) between the first and second porous and antiadhesive sheets (200i, 2002) ; said vacuum distribution pad (120) laying onto the first element (104) so that : the first porous and anti-adhesive sheet (200i) comprises a lower face (S2oi) applied onto an upper face (S«i) of the first element (104) and covering an opening of said at least one vacuum port (108), and the second porous and anti-adhesive sheet (2002) comprises an upper face (S202) which faces a lower face (S102) of the cover (106) when the cover (106) is in its second position (P2), said upper face (8202) of said second porous and anti-adhesive sheet (2OO2) and said lower face (S102) of said cover (106) being suitable to sandwich a product (1 ) to be compacted.[2] The vacuum press device (100) according to claim 1 , wherein the stack of layers of breather mesh (204) comprises at least two layers.[3] The vacuum press device (100) according to claim 1 or 2, wherein the first and second and anti-adhesive sheets (200i, 2OO2) are made of PTFE.[4] The vacuum press device (100) according to any of claims 1 to 3, wherein the peripheral edges (PE1, PE2) of the first and second porous and anti-adhesive sheets (200i, 2OO2) are connected together by a flexible tape (202).[5] The vacuum press device according to claim 4, wherein the flexible tape (202) is made of PTFE.[6] The vacuum press device according to any of claim 1 to 5, wherein the first element (102) forms an angle between 0 and 90° with respect to a horizontal plane.[7] The vacuum press device according to any of claim 1 to 6, wherein the support (102) comprises at least one vacuum port (108) provided on at least one side of said support (102) and communicating with the vacuum port (108) on the first element (104).[8] The vacuum press device according to any of claim 1 to 7, wherein it comprises a plurality of vacuum sources (110) and / or a plurality of vacuum ports (108), the vacuum ports (108) being uniformly distributed on the first element (104) and / or on at least one side of the support (102).[9] A system comprising at least: the vacuum press device (100) according to any of claims 1 to 5; and a stack or prepreg plies which is sandwiched between said upper face (S202) of said second porous and anti-adhesive sheet (2OO2) and said lower face (S102) of said cover (106).[10] A method (300) for compacting a stack or prepreg plies, the method comprising at least the following steps: positioning (400) a stack or prepreg plies in a vacuum press device (100) according any of claims 1 to 5, said stack or prepreg plies being sandwiched between said upper face (S202) of said second porous and anti-adhesive sheet (2OO2) and said lower face (S102) of said cover (106) ; andactuating (402) the vacuum source (110) so as to compact the stack or prepreg plies[11] The method (300) according to previous claim, further comprising at least the following steps: a) positioning the stack or prepreg plies in the vacuum press device (100) onto the vacuum distribution pad (120); b) compacting the stack or prepreg plies; c) removing the compacted stack or prepreg plies from the vacuum pad (120); d) positioning another stack or prepreg plies in the vacuum press device (100) on top of the vacuum distribution pad (120); e) repeating steps b), c) and d).