DEVICE FOR APPLYING A SEALANT TO THE EDGE OF A COMPOSITE MATERIAL PART

Description

[0001] The invention relates to a device for applying a product to the edge of a part made of fiber-reinforced composite material.

[0002] Parts made of a composite material reinforced with electrically conductive or semi-conductive fibers, when assembled within a structure with other materials, in particular metals such as aluminum alloys or steels, carry the risk of triggering galvanic corrosion phenomena, when electrical contact exists between said fibers and said metallic materials. If on the surface of composite parts, the fibers are electrically insulated from the outside, because they are embedded in the resin constituting the matrix, this is not the case for all the edges of the part, or surfaces that have undergone machining such as trimming or drilling. On these surfaces, the ends of the fibers are exposed and likely to come into electrical contact with other parts during assembly. This is the case, for example, of a metal rivet inserted into a hole made in the composite part.

[0003] In order to avoid this phenomenon, particularly in the field of aeronautical applications, an operation called "edging" is generally carried out ( edge sealing in English) of the live edges of these parts. This operation consists of depositing on the live edges of the parts in question, for example by means of a brush, a layer of electrically insulating material, most generally but not exclusively an epoxy resin. This operation is generally carried out manually, it being difficult to automate.

[0004] There figure 1 relating to the prior art, represents the appearance of the edge of a part (100), after carrying out an edging operation with a brush. The resin layer (110) covers the edge of the part well, thus ensuring the electrical insulation of the ends of the reinforcing fibers. For this electrical insulation to be effective, the resin layer thus deposited must reach a minimum thickness at all points, generally greater than 0.2 mm, but must remain below a maximum thickness, of the order of 0.5 mm, so as not to hinder the assembly of the part and also, in the case of aeronautical applications, in order to limit the added mass. The application of such a layer with traditional means, such as a brush or a mini painter's or model roller, results in the formation of a bead (111) extending over the surfaces (101, 102) delimiting said edge.This bead poses difficulties during assembly operations involving the surfaces (101, 102) in question, so that it must be eliminated. The elimination of the bead (111) is also a manual operation, relatively tedious and time-consuming, carried out by scraping using a sharp tool. Thus, it is not uncommon for this scraping operation to account for two-thirds of the total time of an edging operation. Taking the example of a single operator carrying out both the application of the resin on the edge and the scraping of the excess, using a two-component resin, following the initial mixing of the two components, the polymer gradually crosslinks, and this polymerization continues during the scraping operation of a first part, so that when the resin is applied to the second part, the viscosity of the resin has changed and the application conditions are different from one part to another.Thus, the results are not reproducible and a significant amount of resin is wasted because: . not usable beyond a certain stage of polymerization; removed during the scraping operation.

[0005] Document US 4,951,849 describes a device, adaptable to an automatic drilling or riveting unit, for applying a sealing mastic to the edges of a countersink receiving the head of a rivet, more particularly to avoid galvanic couplings between said rivet and the parts thus assembled. The applicator consists of a rigid conical application head, in the shape of the countersink, used coaxially with the drilling axis, which comprises a plurality of radial orifices through which the sealing mastic is dispensed under pressure by means of a peristaltic pump. After drilling and countersinking the hole, the applicator is positioned against the countersink, the sealing mastic is injected through the orifices of the application head and deposited on the edges of the countersink, then the application head is withdrawn. This device requires precise positioning of the head relative to the hole.The application method is only applicable to internal edges forming a closed perimeter, and cannot be used for applying a product to the external edges of a part.

[0006] US 3,904,718 describes a variation of the previous system, and includes a rotating application head driven by a motor. The head first picks up a quantity of sealant by contact and then deposits it on the surfaces to be treated, the rotation of the head allowing for a uniform application of the sealant. This device is effective for treating a small area, such as a countersink, but is not suitable for treating the outer edges of a composite part.

[0007] Document US 2014 / 0263480 describes a device for applying a sealant to the edges of a countersunk hole, comprising a cylindrical applicator provided with means for connecting it to a cartridge containing sealant. The applicator comprises at its end a rigid cylindrical application head comprising radial orifices through which the sealant is delivered. The head is introduced into the bore, the sealant is injected into the orifices, and to ensure uniform distribution of the sealant, the operator rotates the head, over a portion of a revolution, in the bore. Like the other devices presented above, this device is not suitable for treating the outer edges of a part.

[0008] Document JPH 105648 describes a device for the automatic application of a primer to the edge of a substantially rectilinear part, comprising a roller comprising a plurality of discs stacked and threaded onto an axis which is mounted to rotate freely on an articulated arm.

[0009] Document JP 2011 005363 describes a roller for the automatic application of a coating on a surface of complicated shape such as a mechanically welded assembly. Said roller comprises a plurality of stacked porous discs, and a plurality of brushes positioned between said discs. Said discs and brushes are mounted on a hollow shaft. Said hollow shaft is fixed in complete connection to a fixing device, itself capable of being connected to a servo-motor carried by a robot to be driven in rotation

[0010] The invention aims to resolve the drawbacks of the prior art and to this end relates to a tool suitable for the manual or automatic application of a polymerizable sealing product to the edge of a composite part, in accordance with claim 1.

[0011] Thus, the product is applied to the edge of the part by rolling the pad previously impregnated with the product over said edge, but unlike a painter's roller, where the axis of rotation of the application pad relative to the gripping part is perpendicular to the orientation of the gripping, the parallel arrangement of this axis of rotation allows precise control of the application of the product, in particular the application pressure, by keeping the tool as close as possible to the application area, whether the application is carried out manually or using a robot, thus avoiding the formation of a bead. The diameter of the pad is adapted to the thickness of the edge and the intended application, making it possible in particular to apply the product in areas with a small radius. However, the same diameter of applicator pad can be used for a wide variety of contours.

[0012] The invention is advantageously implemented according to the embodiments and variants set out below, which are to be considered individually or according to any technically effective combination.

[0013] According to one embodiment, suitable for manual application of the product to the edge of the part, the sleeve is made of a closed-cell polyolefin foam, the surface cells of which are open due to the process of cutting the sleeve. This embodiment prevents the formation of air bubbles in the applied product when it is taken by contact and applied to the edges of the treated part.

[0014] According to one embodiment, suitable for automatic use of the tool which is the subject of the invention, the sleeve is made of an open-cell foam, and the rod comprises an orifice for injecting the product applied into the foam sleeve.

[0015] Advantageously, the rod is made of polytetrafluoroethylene (PTFE) and its outside diameter is greater than the inside diameter of the tubular sleeve. The low coefficient of friction of this material facilitates the installation and replacement of the sleeve, in particular when the applied product begins to polymerize or is polymerized. The tensioning of the foam sleeve when it is slipped onto the rod ensures its retention on the latter, and promotes the uptake and transfer of the applied product, in particular by opening the cells of the foam, on the surface or throughout its thickness depending on the embodiment.

[0016] Advantageously, the rod has a protrusion shape for axial positioning of the sleeve on said rod.

[0017] According to an embodiment suitable for manual use of the tool which is the subject of the invention, the gripping part is suitable for holding in the hand, the application part being coaxial with the gripping part.

[0018] According to a particular embodiment, preferably adapted to automatic use of the tool, the gripping part is fixed to means fixed in space, and the application of the product is carried out by moving the part relative to the tool.

[0019] The invention is set out below according to its preferred embodiments, which are in no way limiting, and with reference to the figures 1à 5 , in which: there figure 1 relating to the prior art represents, in a partial sectional view, an example of the result of the edge edging treatment of a part made of composite material using the tools of the prior art; figure 2 shows an exemplary embodiment of a tool which is the subject of the invention according to a longitudinal sectional view; the figure 3 shows in a front view another exemplary embodiment not forming part of the invention; the figure 4 is a partial AA sectional view defined figure 3 , of an example of implementation of the application part; and the figure 5 represents, in a front view, an example of the use of the tool which is the subject of the invention in a fixed position.

[0020] Figure 2 , according to an exemplary embodiment, preferably but not exclusively adapted to manual use, the tool (200) which is the subject of the invention comprises a gripping part, comprising a handle (210) defining a gripping axis (201). Said handle is made of an aluminum alloy tube. An axis (220) is guided in pivot connection in said handle (210), for example by means of PTFE bearings (212) crimped into the internal passage of the handle at each of its ends. A rod (230), for example made of PTFE, is centered at the end of the axis (220) and fixed to it, for example, by means of an elastic pin (232) passing through said rod (230) and the axis (220), so that the rod is also in pivot connection, and free to rotate relative to the handle (210).

[0021] The gripping part is, according to exemplary embodiments, adapted to be held in the hand in the case of a tool adapted for manual application. In this case the diameter of the tubular part (210) is between 8 mm and 20 mm without these values ​​being limiting, so that said handle is held in the hand like a pen.

[0022] According to exemplary embodiments, the external shape of the tubular part is not of circular section, but of elliptical, polygonal or other section, for better gripping ergonomics.

[0023] The gripping of this gripping part is, according to an embodiment implementing automated edging of the part, carried out by a robot by means of a gripper or any other effector ensuring such gripping. By extension, it can be fixed by fixing means to a fixed part of the robot, maintaining the pivot connection of the axis (220) and the rod (230) relative to this gripping part.

[0024] In all cases, the rod and the sleeve are in pivot connection with an axis parallel to the cylindrical axis of the sleeve relative to the gripping part.

[0025] According to an exemplary embodiment, the axis of the pivot connection of the rod relative to the handle is coaxial with the gripping axis (201). The rod (230) ends in a protrusion shape (235), according to this exemplary embodiment, with a double-chamfered shoulder to allow easy installation and removal of a sleeve on the rod.

[0026] A tubular foam sleeve (240) is slipped onto said rod (230), it is stopped and positioned axially on the latter against the protrusion shape (235). The rod (230) and pad (240) assembly constitutes the application part (250) of the tool which is the subject of the invention.

[0027] The inner diameter of the foam sleeve (240) when not installed on the rod (230) is less than the outer diameter of said rod, so that once threaded, the sleeve is in tension and firmly held on the rod.

[0028] By way of non-limiting example, the inner diameter of the tubular sleeve in the free state is 5 mm while the outer diameter of the rod (230) is 8 mm. According to a detailed view, the sleeve is, according to this exemplary embodiment, made of a closed-cell foam.

[0029] However, the sleeve cutting process reveals open cells (241) on its surface. For example, the foam used for the sleeve is a polyolefin foam with a density of 29 kg / m 3< with closed cells, with an average cell diameter of 0.65 mm.

[0030] The foam sleeve constitutes a pad for applying the product to be applied to the edge of the part (100). The purpose of said product is to ensure the sealing of the edge of the part and in the case where the reinforcement used in the composite part is electrically conductive, for example carbon fibers, to ensure the electrical insulation of the end of said fibers.

[0031] For this purpose, the applied product is a polymerizable product, generally a two-component product such as an epoxy resin or a sealant. Such products generally have a high viscosity which also evolves as the product polymerizes during its open application time.

[0032] In order to carry out this application, in the case of manual application, the said pad is first loaded with product by contact, by rolling the sleeve, mounted on the tool, on a surface coated with the product to be applied, like a painter's roller. In the case of a two-component polymerizable product, the sleeve is loaded with the two components previously mixed.

[0033] The product penetrates into the open porosities (241) on the surface of the sleeve, by capillarity, without creating air bubbles. Once the sleeve is coated, the product is deposited on the edge of the part (100) to be treated by rolling the sleeve on said edge under slight pressure.

[0034] The product is thus deposited uniformly on the edge of the part without creating air bubbles or bulges. The coaxial positioning of the sleeve's rotation axis and the gripping orientation axis ensures fine control of the pressure exerted during application of the product as well as the trajectory followed with the tool.

[0035] The nature of the foam constituting the sleeve is adapted according to the nature of the product applied. The example of foam presented above is more particularly adapted to the deposition of a two-component product comprising a modified epoxy base and an amine-type catalyst, for a viscosity between 10 Pa.s and 500 Pa.s, with an open application time of the order of 90 minutes. The sleeve is thus changed approximately every hour to allow it to retain its flexibility.

[0036] Advantageously, the rod (230) is made of or is coated with a suitable material, such as polytetrafluoroethylene (PTFE), preventing the sleeve loaded with the product applied to the said rod from sticking and facilitating its replacement.

[0037] Figure 3 , according to another exemplary embodiment suitable for automated use not forming part of the invention, this comprises a gripping part comprising a coupling form (310) with the effector holder of a robot or a machine tool spindle and thus defining a gripping axis (301). According to this exemplary embodiment, not forming part of the invention, the tool (300) comprises two application parts (352, 353) each in pivot connection, free to rotate, relative to the gripping part, along axes (302, 303) parallel to the gripping axis (301). Each of the application parts is of a structure similar to that of the previous exemplary embodiment ( figure 2 ) and comprises a PTFE rod onto which is slipped a tubular foam sleeve (342, 343), acting as an application pad.

[0038] According to this embodiment example not forming part of the invention, the two application parts (352, 353) are of different diameters and allow, for example, for one (352) of larger diameter, to treat edges extending over significant distances, and for the other (353), of reduced diameter, to treat areas where the edge of the part follows tight radii of curvature. The selection of one or the other of the application parts is carried out, according to this embodiment example, by a 180° rotation of the gripping part around the gripping axis (301).

[0039] As for the previous example of realization ( figure 2 ) the application of the product on the edge to be treated is carried out by rolling one or other of the application parts (351, 352) on the edge to be treated and under slight radial pressure. According to implementation variants, this application is carried out while the part to be treated is fixed in a suitable assembly and the robot, the manipulator or the machine tool moves the tool relative to the part, or, the part is also supported by a robot or a manipulator and the movement of the tool relative to the part is obtained by the combination of the movements of the two robots or manipulators.

[0040] The loading of the pad with product to be applied is, according to an exemplary embodiment, obtained as in the case of manual application by rolling the application part (352, 353) on a surface coated with the product to be applied, this operation being carried out by the robot or the manipulator.

[0041] Figure 4 , according to another embodiment, the rod (430) supporting the foam sleeve (342) comprises a central channel (431) and radial orifices (432) opening under the foam sleeve (342), and through which the product to be applied is injected at a controlled flow rate. The injection of product is carried out, for example, by means of a peristaltic pump (not shown) or any other means making it possible to avoid the creation of air bubbles in the product during said injection.

[0042] In the case where the applied product is a two-component product, the said components have been mixed, prior to injection.

[0043] In this case, the sleeve is made of open-cell foam, in order to allow the injected product to travel to the outer surface of the sleeve (342, 343). The principle of applying the product to the part to be treated remains the same.

[0044] Figure 5 , according to another example of implementation, the gripping part (510) of the tool (500) which is the subject of the invention is fixed to a fixed station. The characteristics of the application part (550) remain the same, with means for injecting the product to be applied under the foam sleeve as shown figure 4 , and a sleeve made of an open-cell foam. The principle of application of the product remains the same but is obtained by moving the part to be treated, for example by means of a robot, relative to the application part (550). Alternatively, the part is moved manually opposite the tool (500) at a fixed position.

[0045] The above description and the examples of embodiment show that the invention achieves the intended purpose and simplifies the process of edging the edges of a part made of a fiber-reinforced composite material, while improving quality. Thus, compared to edging techniques using prior art tools, such as a brush or modeling roller, the use of the tool that is the subject of the invention, in its manual version, makes it possible to very significantly reduce the time of the edging operation, by reducing the application time and eliminating scraping operations. Indeed, it is noted that the use of the tool that is the subject of the invention virtually eliminates the need for bead scraping operations, thereby also reducing the risk of accidents at work during this operation. Adaptation of personnel is also very rapid and training time is reduced.In automatic use, programming is simplified and allows the use, for example, of the generated trajectories for part routing programs in milling, by simply changing the values ​​of the tool offsets.

Claims

1. A tool (200, 500) adapted to a manual or an automatic application of a polymerizable sealant on an edge of a composite part (100) characterized in that it comprises: a. a grip portion comprising a handle (210), defining an orientation axis (201) of the grip, the handle consisting of an aluminum alloy tube and an axis (220) coaxial with the orientation axis (201) and pivotally guided about the orientation axis (201) in the handle (210, 510); b. an application part (250), comprising a rod (230, 430) centered at an end of the axis (220) and attached to that so that the rod is also in pivot link and free to rotate with respect to the handle (210); C. a cylindrical application pad (240) consisting of a tubular foam sleeve (240) slept onto the rod (230,430), made of a polyolefin foam comprising open cells on a surface of the sleeve, configured ti absorbing a product and depositing it on a surface by contact with the surface, by rolling the sleeve, attached to the tool, on the surface.

2. The tool according to claim 1, adapted to the manual application of the sealing product, wherein the foam of the sleeve (230) comprises open cells (241) on the surface and closed cells in a thickness of the sleeve.

3. The tool according to claim 1, adapted for the automatic application of the sealant, wherein the sleeve is made of an open cell foam, and wherein the rod (430) comprises an orifice (432) for injecting the sealant to be applied into the foam of the sleeve.

4. The tool according to claim 1, wherein an outer surface of the rod in contact with the sleeve is made of polytetrafluoroethylene (PTFE)with an outer diameter greater than an inner diameter of the tubular sleeve.

5. The tool according to claim 1, wherein the rod comprises a protruding shape (235) for an axial positioning of the sleeve on the rod.

6. The tool according to claim 2, wherein an outer diameter of the handle (210) is comprised between 8 mm and 20 mm such that the handle is grasped in the manner of a pen.

7. The tool according to claim 3, wherein the grip portion (110) is configured for gripping by a robot or manipulator.

8. The tool (500) according to claim 3, wherein the grip portion (510) is attached to means fixed in space, and wherein the application of the product is carried out by moving the part relative to the tool.