Tool for pressurizing working region of part made of composite material, robot equipped with such tool, and method for repairing part made of composite material using such tool

Abstract

The invention relates to a pressurizing tool (3) for pressurizing a working area (2) of a part (1) made of a composite material, the composite material comprising a fibrous reinforcement densified by a resin, in which working area (2) pre-impregnated fibres (22) are applied, and which pressurizing tool (3) is configured to be removably mounted on a robot, the pressurizing tool (3) comprising: an articulated skeleton (11), which is arranged on the working area (2), the hinged framework is constructed to be matched with the shape of the part (1) around the working area (1); at least one expandable membrane (15) fixed to the skeleton (11) and configured to apply a predetermined and uniform pressure to the working area (2) in an expanded state.

Description

Technical Field

[0001] The present invention relates to the repair or manufacture of parts made of composite materials comprising fiber reinforcements, in particular fibers pre-impregnated with resin. Background Art

[0002] The prior art includes documents US-A1-2011 / 259515, US-A1-2021 / 379845 and US-B1-6318433.

[0003] Many parts used in different fields such as the automotive and aerospace industries include parts made of composite materials. Composite materials enable the production of lightweight parts with high mechanical properties. When fiber reinforcements are made of fibers pre-impregnated with resin, these fibers can be used to produce parts of any size and with complex three-dimensional shapes.

[0004] Parts made of composite materials are sometimes damaged during manufacturing, operation, maintenance or storage, for example due to impact. Parts made of composite materials can be repaired when the damaged area is limited. The same type of material is used, in particular fibers pre-impregnated with resin or dry fibers impregnated by hand.

[0005] The densification of the resin-impregnated fibers requires a polymerization phase, which is generally carried out in an autoclave. In fact, the autoclave makes it possible to apply heat and pressure cycles whose purpose is to compact the fibers in order to keep them in place on the part made of composite material to be repaired, to gel the resin impregnating the fibers and to obtain a good resin / fiber ratio. The autoclave is a large and expensive tool installed in workshops for the manufacture and / or repair of parts made of composite materials.

[0006] One disadvantage is that the parts must be disassembled and transported to these shops. Also, not all shops are equipped with large, expensive autoclaves, so some cannot accommodate very large parts.

[0007] It is possible to repair parts made of composite materials while still assembled on the equipment, i.e. without the need for an autoclave. During this repair, fibers pre-impregnated with resin are placed over the damaged area and covered with a bladder which is connected in a sealed manner to the part made of composite materials and which enables the damaged area to be evacuated. However, it is not possible to reach pressure parameters that allow obtaining parts with high mechanical strength, since the vacuum of the bladder limits the pressure of the atmospheric pressure applied to the area where the repair is to be carried out and the capacity of the vacuum pump used. For example, the pressure applied to the pre-impregnated fibers is less than 1 bar, which is insufficient to achieve the required thermomechanical properties of the part.

[0008] There is a need to address some or all of the above disadvantages. Summary of the invention

[0009] The object of the present invention is to provide a solution for autonomously and quickly polymerizing parts made of composite materials anywhere with at least sufficient pressure.

[0010] According to the invention, this is achieved by a pressing tool for pressurizing a working area of ​​a part made of composite material, the composite material comprising a fiber reinforcement densified by a resin, pre-impregnated fibers being applied in the working area, and the pressing tool being configured to be removably mounted on a robot, the pressing tool comprising an articulated skeleton and at least one inflatable membrane, the articulated skeleton being configured to adapt the shape of the part around the working area, the at least one inflatable membrane being fixed to the skeleton and being configured to apply a predetermined and uniform pressure to the working area in an inflated state.

[0011] This solution therefore makes it possible to achieve the above-mentioned objectives. In particular, the use of such a tool makes it possible to apply a specific and uniform pressure to the entire working area of ​​a part made of composite material. The construction of this tool means that it can be used in any workshop with all the characteristics of an autoclave, even under the wing of an aircraft. This reduces the need to transport parts from one place to another and means that energy and human resources are spent only on what is needed. In addition to this, such a tool makes it possible to meet ecological challenges by avoiding the transportation of bulky and fragile parts for repair and avoiding waste by repairing damaged parts.

[0012] The pressurizing tool may also include one or more of the following features, taken alone or in combination:

[0013] - The pressing means comprises a heating system mounted on the expandable membrane to apply a predetermined temperature.

[0014] - The articulated frame comprises a plurality of segments articulated together.

[0015] - The inflatable membrane is connected to an inflation fluid supply.

[0016] The inflatable membrane has a height in the inflated state comprised between 2 cm and 5 cm.

[0017] -The fluid supply source is either built into the pressurizing tool or is portable.

[0018] - The electrical energy source is either mounted on the press tool or portable.

[0019] - The pressing tool comprises an attachment system for removably attaching to the robot.

[0020] - The pressure and temperature applied to the working zone are constant during the polymerization phase.

[0021] -The pressure applied to the working area is uniform.

[0022] - The temperature applied to the working area is between 60°C and 180°C.

[0023] The invention also relates to a collaborative robot comprising a chassis, an arm carried by the chassis, and an end effector removably connected to the arm, the end effector being intended to be moved by the arm and formed by a press tool as described above.

[0024] The invention also relates to a method for repairing a damaged area of ​​a part made of a composite material, the composite material comprising a fiber reinforcement densified by a resin, the method comprising:

[0025] - a step of applying pre-impregnated fibers pre-impregnated with resin to the damaged area forming the working area, and

[0026] - a step of evacuating the inner cavity formed by the bladder which covers the preimpregnated fibers in the working area in a sealed manner,

[0027] The method includes:

[0028] - a step of arranging a pressing tool having any of the preceding characteristics relative to the preimpregnated fibers covered by the bladder, and

[0029] - a polymerisation step of polymerising the preimpregnated fibres, wherein at least one sub-step of applying a predetermined and uniform pressure to the bladder covering the preimpregnated fibres by means of an inflatable membrane is carried out.

[0030] The method may further include one or more of the following features and / or steps, taken alone or in combination:

[0031] - The predetermined pressure is between 1 bar and 3 bar.

[0032] - The polymerisation step comprises a sub-step of applying a predetermined temperature.

[0033] - The predetermined temperature is between 60°C and 180°C.

[0034] The method comprises a step of applying a counter pressure to the part made of composite material.

[0035] - The counter pressure is applied by another pressurizing tool.

[0036] The application of the predetermined temperature is performed by two pressing tools arranged on both sides of the part made of composite material.

[0037] - Controlling the pressure and temperature applied to the working area during the polymerization phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention will be better understood and other objects, details, features and advantages of the invention will become clearer by reading the following detailed description of an embodiment of the invention given as a purely illustrative and non-limiting example, with reference to the attached schematic diagram, in which:

[0039] Figure 1 is a schematic side view of an example of a press tool equipped with a collaborative robot according to the present invention;

[0040] Figure 2 is a schematic top view of an example of an embodiment of a component of a pressing tool according to the present invention;

[0041] Figure 3 is a perspective view of two collaborative robots for repairing a part made of composite material according to the present invention. DETAILED DESCRIPTION

[0042] Figure 1 A part made of a composite material is partially shown. The composite material comprises a fiber reinforcement densified by a resin. More specifically, the fiber reinforcement consists of a plurality of plies of fibers pre-impregnated with a resin. The part made of the composite material can be assembled to a motor vehicle, an aircraft, a turbine nacelle for an aircraft, etc.

[0043] exist Figure 1 In the embodiment, the part made of composite material comprises a damaged area which needs to be repaired. The damaged area forms a working area 2. For this purpose, Figure 1 Also shown is a pressing tool 3 which is designed to facilitate the repair of the working area 2 .

[0044] The pressing tool 3 is configured to be equipped with a robot 4, in particular a collaborative robot, which also Figure 1 The collaborative robot is equipped with a detection device 5 and an electronic control system 6, the detection device 5 being connected to the electronic control system 6 so that the electronic control system can move and / or evolve in its working environment. Each robot 4 is designed to perform a specific task alone (autonomously) or in collaboration with one or more operators or with other collaborative robots also operating in the robot's working environment. These tasks are, for example, manipulation, repair, movement or other possibly more detailed tasks. These collaborative robots are also called "cobots".

[0045] Advantageously but not limited to, the detection device 5 can be a presence sensor, a position sensor, a camera, a measuring device, etc., and / or a combination of these devices. The detection device 5 is mounted on different units of the robot 4 .

[0046] Advantageously, the electronic control system 6 is equipped with computing means, memory and information processing means, enabling the robot 4 to act and / or react according to the information received from the detection means 5 .

[0047] The robot 4 includes a chassis 7, an arm 8 supported by the chassis 7, and an end effector 9 detachably connected to the arm 8. The detection device 5 may be mounted on the end effector 9 and / or the arm 8 and / or the chassis 7.

[0048] Advantageously, the chassis 7 is mounted on a moving device (not shown) so that the robot 4 can move autonomously in its working environment. Alternatively, the chassis is configured so that it can be fixed to a working support.

[0049] Advantageously, but not limited to, the arm 8 comprises a plurality of parts 10a, 10b, 10c articulated to one another by, for example, pivot connections or ball-and-socket connections with different axes, such that the end effector 9 can be easily manipulated in a plurality of directions.

[0050] The end effector 9 is designed to perform the various tasks for which the robot 4 is used. The end effector 9 represents the head of the robot and is advantageously formed here by the pressing tool 3.

[0051] Reference Figure 1 and Figure 2 , the pressing tool 3 comprises an articulated frame 11 which is configured to adapt to the shape of the working area 2. The term "articulated frame" refers to an organ composed of a plurality of elements articulated together, such that the organ is deformable.

[0052] In this example, the skeleton 11 comprises a plurality of segments 12 articulated together along at least one joint 13. The joint 13 may be at least one pivot link. In particular, the segments 12 are arranged to form a grid and at least one end 12a, 12b of each segment 12 is articulated to one end 12a, 12b of an adjacent segment. The segments defining the perimeter may form a square, a rectangle or any other shape that enables the segments to articulate and that enables the skeleton 11 to deform relative to the working area of ​​the part.

[0053] An advantageous but non-limiting feature is that each joint 13 can be locked in position to hold a membrane 15, described later, in a compressed state.

[0054] The pressurizing tool 3 further comprises a membrane 15, which is configured to apply a predetermined and uniform pressure to the working area 2. The membrane 15 is expandable. The membrane 15 is adapted to occupy a deflated state and an expanded state. The expandable membrane 15 is Figure 11 is shown in its expanded state. Advantageously, the membrane 15 is fixed to the skeleton 11 to make it easier to handle the tool 3 and save repair time. Advantageously, a predetermined pressure is applied in the expanded state so that the pressure in the membrane is uniform.

[0055] To this end, the inflatable membrane 15 is connected to an inflation fluid supply 20 . Figure 2 Schematically shown in FIG. 2 is a supply source 20. The inflation fluid may be air or oil or any other liquid or gaseous fluid. The fluid supply source 20 may include a pump or a compressor. Similarly, the fluid supply source 20 may be mounted on the pressurizing tool 3 and / or the collaborative robot 4. In this way, the supply source 20 may be easily moved with the pressurizing tool and / or the collaborative robot so that the repair may be performed anywhere, for example, under the wing (in the case of aircraft parts) or in a workshop.

[0056] Advantageously, but not limited to, the membrane 15 has an outer surface whose perimeter is substantially equal to the perimeter of the skeleton 11, so that the pressure is better distributed over the entire wall of the membrane 15. In particular, the membrane 15 has a first wall 16 and a second wall 17 opposite each other. The two walls 16, 17 are connected by a peripheral edge 18 that defines the perimeter of the membrane 15. The first wall 16 is connected to the skeleton 11. The connection can be made by gluing or any other means. The second wall 17 is designed to face the working area 2.

[0057] The predetermined pressure is usually between 1 bar and 10 bar. Preferably, the predetermined pressure is 2.5 bar.

[0058] An advantageous feature is that, in its expanded state, the membrane 15 has a height h1 typically comprised between 2 cm and 5 cm. The membrane 15 may also have a height greater than this value. The height h1 is measured between the first wall 16 and the second wall 17 .

[0059] The expandable membrane 15 is advantageously made of a flexible material and / or soft material. For example, the material may be a polymer such as polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), an elastomer, or the like.

[0060] Also in Figure 1 In the example, the pressing tool 3 comprises a heating system 30 mounted on the expandable membrane 15 in order to apply a predetermined temperature. Preferably, the heating system 30 is attached to the expandable membrane. In this example, the heating system 30 comprises a plurality of heating members 31a, 31b, ..., which are distributed over the entire second wall 17 of the expandable membrane.

[0061] Advantageously but not limited to, the heating members 31a, 31b have a height h2 between 1 mm and 5 mm and preferably between 1 mm and 2 mm. The heating system 30 is connected to an electrical energy source 32. Like the fluid supply source, the electrical energy source 32 can be carried on the press tool 3 and / or the collaborative robot, or can be easily transported to facilitate repairing parts made of composite materials anywhere.

[0062] The predetermined temperature is advantageously between 60°C and 180°C.

[0063] Reference Figure 2 , the pressing tool 3 is equipped with an attachment system 14 which enables the pressing tool to be removably attached to the robot arm.

[0064] The pressing tool 3 is particularly suitable for repairing damaged areas of parts made of composite materials and also for producing parts made of composite materials.

[0065] A method for repairing a part made of a composite material will now be described. The method comprises the following steps:

[0066] - pre-impregnated fibers 22 with resin applied in the working area,

[0067] - evacuating the inner cavity 23 formed by the bladder 24 which covers the pre-impregnated fibers 22 in the working area in a sealed manner,

[0068] - positioning the portable press tool 3 opposite the pre-impregnated fibres covered by the bladder, and

[0069] - a step of polymerizing the preimpregnated fibers, wherein at least one sub-step of applying a predetermined and uniform pressure to the bladder covering the preimpregnated fibers is performed by means of an inflatable membrane.

[0070] Reference Figure 1 , the method comprises a step of preparing a working area 2 before applying the preimpregnated fibers. The working area 2 is located on a first surface 25 of the part made of composite material. The part made of composite material comprises a second surface 26 opposite to the first surface.

[0071] The preparation step consists in removing the plies and / or fibers that are no longer cohesive with the other plies and / or fibers of the part made of composite material from the work area 2. In other words, this preparation step consists in cleaning the work area 2.

[0072] In the step of applying the resin pre-impregnated fibers 22, the fibers are applied in the form of a plurality of plies one after another. Advantageously, but not restrictively, the plies can be produced using two-dimensional (2D) weaving. The pre-impregnated fibers include, for example, fibers made of carbon, glass, polyamide, Kevlar, ceramic, copper, bronze or a mixture of these materials.

[0073] The fibers are pre-impregnated at an early stage (the fibers are already pre-impregnated when supplied), or the fibers are dried and impregnated with resin before being arranged on the work area. Thus, the term "pre-impregnated" refers to fibers that have been impregnated with resin before the step of applying the fibers.

[0074] The resin is able to withstand high temperatures, in particular temperatures exceeding 120° C. This type of resin makes it possible to obtain composite materials having high mechanical properties. Examples of resins are epoxy-based thermosetting resins or phenolic resins, such as polybismaleimide (BMI).

[0075] The method includes the step of positioning a bladder 24 to cover the pre-impregnated fibers 22 in a sealed manner. The bladder 24 forms an inner cavity 23 in which the pre-impregnated fibers 22 are located. The bladder 24 also covers a portion of the first surface 25 surrounding the pre-impregnated fibers. The bladder 24 is in the form of a soft and flexible skin. The bladder 24 is removably attached to the first surface in a sealed manner. In particular, the bladder 24 has an edge attached to the first surface 25. The attachment is performed by any means that enables the bladder to be sealed, installed, and easily removed.

[0076] Advantageously but without limitation, a gasket 27 is provided at the attachment to prevent air or other fluids from entering the inner cavity 23 formed by the bladder 24 and the first surface 25 of the part made of composite material. Advantageously, the gasket 27 is made of a deformable material.

[0077] The evacuation step of the bladder 24 is performed by evacuation means 28 which enable extraction of the air or gas present in the inner cavity 23. The bladder 24 in fact comprises a suction orifice 29 connected to the evacuation means 28. The suction orifice advantageously comprises a vacuum pump or a compressor.

[0078] The polymerization step comprises applying at least one predetermined and uniform pressure through the inflatable membrane 15. To apply this pressure, the membrane 15 is inflated with an inflation fluid. The skeleton 11 pressing on the inflatable membrane 15 enables the inflatable membrane 15 to distribute the pressure uniformly over the entire working area 2. The pressure is Figure 1 The plane shown is oriented in a direction parallel to the vertical axis. Here, this direction is parallel to the axis 35 of the attachment system 14 of the tool 3. The pressure is directed towards the working area 2. Advantageously, the (controlled) pressure is constant during the polymerization phase.

[0079] During the step of positioning the tool 3 opposite the working area and the preimpregnated fibers, the articulated skeleton 11 is positioned at a distance from the preimpregnated fibers, in particular the bladder, so that when the membrane 15 is expanded, the membrane 15 is in contact with the bladder 24. The predetermined distance from the first surface 25 is between 1 cm and 3 cm. The heating members 31a, 31b of the heating system 30 are positioned between the expandable membrane 15 and the bladder 24.

[0080] The polymerisation step also comprises applying a predetermined temperature to the pre-impregnated fibres. This temperature is applied by a heating member 31. During the polymerisation phase the predetermined (controlled) temperature is also constant.

[0081] The pressure required for polymerization is provided by a single pressurizing tool (the head of the collaborative robot) comprising at least one inflatable membrane 15 that enables uniform and consistent application of pressure. The temperature and pressure enable the layup of preimpregnated fibers to densify.

[0082] The method described can also be used to produce parts made of composite materials.

[0083] Figure 3 Another embodiment of a method for repairing or manufacturing a part made of composite material is shown. This embodiment is implemented in particular in the context of a very flexible part made of composite material. In this embodiment, the method comprises a further step of applying a counterpressure to the part made of composite material. More specifically, the counterpressure is applied to the second surface 26 in the working area. This configuration ensures that the part is held in place and prevents deformation of the part made of composite material. Advantageously, but not exclusively, the counterpressure is implemented by another pressurizing tool 3'. This other pressurizing tool will preferably be carried by another collaborative robot 4'.

[0084] In one embodiment, the predetermined temperature is applied by two pressing tools 3, 3' arranged on both sides of the part 1 made of composite material. This ensures good heat diffusion and distribution in the case of thick parts made of composite material. The fact that the part is so thick means that the part is not soft and there are temperature diffusion problems. The polymerization of the preimpregnated fibers is uniform and therefore accelerated.

Claims

1. A pressing tool (3) for pressing a working area (2) of a part (1) made of composite material, the composite material comprising a fiber reinforcement densified by resin, pre-impregnated fibers (22) being applied in the working area (2), and the pressing tool (3) being configured to be removably mounted on a robot, the pressing tool (3) comprising: - an articulated frame (11) configured to adapt the shape of the part (1) around the working area (1), and - at least one inflatable membrane (15) fixed to the frame (11) and configured to apply a predetermined and uniform pressure to the working area (2) in an inflated state.

2. Pressing tool (3) according to the preceding claim, characterized in that The pressing tool comprises a heating system (30) mounted on the expandable membrane (15) to apply a predetermined temperature.

3. A pressing tool (3) according to any one of the preceding claims, characterised in that The articulated frame (11) comprises a plurality of segments (12) articulated together.

4. A pressing tool (3) according to any one of the preceding claims, characterised in that The inflatable membrane (15) is connected to an inflation fluid supply (20).

5. Pressing tool (3) according to any one of the preceding claims, characterized in that The inflatable membrane (15) has a height (h1) in the inflated state between 2 cm and 5 cm.

6. Pressing tool (3) according to any one of the preceding claims, characterized in that The press tool comprises an attachment system (14) for removably attaching to a collaborative robot (4).

7. A collaborative robot (4), comprising a chassis (7), an arm (8) carried by the chassis (7), and an end effector (9) removably connected to the arm (8), the end effector (9) being intended to be moved by the arm (8) and being formed by a pressurizing tool (3) according to any one of the preceding claims.

8. A method for repairing a damaged area of ​​a part (1) made of a composite material, the composite material comprising a fiber reinforcement densified by a resin, the method comprising: - a step of applying pre-impregnated fibers (22) pre-impregnated with resin to the damaged area forming the working area (2), and - a step of evacuating the inner cavity (23) formed by a bladder (24) which covers the pre-impregnated fibers (22) in the working area (2) in a sealed manner, Characterized in that the method comprises: - a step of arranging a pressing tool (3) according to any one of claims 1 to 6 opposite the preimpregnated fibers covered by the bladder (24), and - a polymerization step of polymerizing the preimpregnated fibers (22), wherein at least one sub-step of applying a predetermined and uniform pressure to the bladder (24) covering the preimpregnated fibers (22) is performed through the expandable membrane (15).

9. Repair method according to the preceding claim, characterized in that The predetermined pressure is between 1 bar and 3 bar.

10. The repair method according to claim 8 or 9, characterized in that: The polymerizing step comprises a sub-step of applying a predetermined temperature.

11. Repair method according to the preceding claim, characterized in that The predetermined temperature is between 60°C and 180°C.

12. Repair method according to the preceding claim, characterized in that The repair method comprises the step of applying a counter pressure to the part (1) made of composite material.

13. Repair method according to the preceding claim, characterized in that The counterpressure is applied by another pressure means (3').

14. Repair method according to the preceding claim, characterized in that The application of the predetermined temperature is performed by two pressing tools (3, 3') arranged on both sides of the part made of composite material.

15. The repair method according to claim 10, characterized in that: The pressure and temperature applied to the working zone are controlled during the polymerization step.

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