WO2019179960A1

WO2019179960A1 - Device for applying a sealing product to the edge of a part made from composite material

Info

Publication number: WO2019179960A1
Application number: PCT/EP2019/056738
Authority: WO
Inventors: Claire Dumas; Julie VAUDOUR; Guenael ESNAULT; Sébastien PASQUIER
Original assignee: Daher Aerospace
Priority date: 2018-03-17
Filing date: 2019-03-18
Publication date: 2019-09-26
Also published as: FR3078903B1; FR3078903A1; MA52068A; EP3768437A1

Abstract

A tool (200) suitable for manually or automatically applying a polymerisable sealing product to the edge of a composite part (100), said tool comprising: a. a fixed gripping portion (210) defining a grip orientation axis (201); b. an application portion (250), linked to the gripping portion so as to be able to pivot about an axis parallel to the grip orientation axis (201), and freely rotate with respect to the gripping portion, and comprising a rod (230) extending along the axis of rotation (201) of the link; c. characterised in that it comprises a cylindrical application pad (240) made up of a tubular foam sleeve (240) threaded onto the rod (230), constituted by a polyolefin foam comprising cells (241) open on the surfaces of the sleeve, capable of absorbing a product and of depositing in on a surface by contact with said surface.

Description

DEVICE FOR APPLYING A SEALANT ON THE SINGING OF A COMPOSITE MATERIAL PART

The invention relates to a device for applying a product to the edge of a piece of composite material with fibrous reinforcement.

Parts made of a composite material reinforced with electrically conductive or semiconducting fibers, when assembled within a structure with other materials, cause metals such as aluminum alloys or steels, risks of triggering galvanic corrosion phenomena, when an electrical contact exists between said fibers and said metallic materials. If on the surface of the composite parts, the fibers are electrically insulated from the outside, because embedded in the resin constituting the matrix, it is not the same for all the songs of the room, or surfaces having undergone such machining than 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 in a hole made in the composite part.

In order to avoid this phenomenon, especially in the field of aeronautical applications, it is generally carried out an operation called "edge sealing" (English edge sealing) of the live edges of these parts. This operation involves 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 performed manually, it being difficult to automate.

Figure 1 relating to the prior art, shows the appearance of the edge of a workpiece (100), after performing a brush edging operation. The resin layer (110) covers the edge of the part well, thus ensuring electrical insulation of the ends of the reinforcing fibers. For this electrical insulation to be effective, the resin layer thus deposited must reach at all points a minimum thickness, generally greater than 0.2 mm, but must remain within 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, to limit the mass added. The application of such a layer with conventional means, such as a brush or a mini roller painter or model, causes the formation of a bead (1 1 1) extending on the surfaces (101, 102 ) delimiting said song. This bead poses difficulties during assembly operations involving the surfaces (101, 102) in question, so it must be eliminated. The elimination of the bead (1 1 1) is also a manual operation, relatively tedious and long, achieved by scraping with a sharp tool. Thus, it is not unusual for this scratching operation to account for two-thirds of the total time of a border operation. Taking the example of a single operator performing both the application of the resin on edge and scraping the excess, using a two-component resin, following the initial mixing of the two components, the polymer crosses progressively 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 the first one. one room to another. Thus, the results are not reproducible and a large quantity of resin is wasted because:

- not usable beyond a certain stage of polymerization;

- removed during the scratching operation.

The document US Pat. No. 4,951,849 describes a device, adaptable to an automatic drilling or riveting unit, for applying sealant to the edges of a countersink that receives 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 form of milling, used coaxial with the drilling axis, which comprises a plurality of radial orifices through which the sealant is dispensed under pressure by means of a peristaltic pump. After drilling and milling the hole, the applicator is positioned against the countersink, the sealant is injected through the holes of the application head and deposited on the edges of the countersink, then the application head is removed. . This device requires precise positioning of the head relative to the hole. The method of application is only applicable on internal edges forming a closed perimeter, and is not usable for the application of a product on the outer edges of a room. US 3,904,718 discloses an alternative of the previous system, and includes a rotational application head driven by a motor. The head first recovers a quantity of sealant by contact and then deposits it on the surfaces to be treated, the rotation of the head allowing uniform application of the sealant. This device is effective for treating a small area, such as milling, but is not suitable for treating the outer edges of a composite part.

Document US 2014/0263480 discloses 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 putty. 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 a portion of a turn of the head in the bore. Like the other devices presented above, this device is not suitable for treating the outer edges of a room.

The aim of the invention is to solve the disadvantages of the prior art and for this purpose concerns a tool adapted to the manual or automatic application of a polymerizable sealant to the edge of a composite part, which tool comprises:

at. a gripping portion, fixed, defining an axis of orientation of the gripping;

b. an application portion, in pivot connection with the gripping portion, along an axis parallel to the axis of orientation of the grip, and free in rotation with respect to the gripping portion and comprising a rod extending according to the axis of rotation of the pivot connection;

vs. characterized in that it comprises a cylindrical applicator pad consisting of a sleeve of tubular foam threaded on the rod, consisting of a polyolefin foam comprising cells open on the surfaces of the sleeve, able to absorb a product and to the deposit on a surface by contact with said surface. Thus, the product is deposited on the edge of the piece by rolling the pad previously impregnated with the product on said edge, but unlike a painter's roll, where the axis of rotation of the application pad with respect to the gripping portion 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, including the application pressure, keeping the tool as close to the application area, whether the application is done 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, allowing in particular to apply the product in areas of small radius. However, the same applicator pad diameter is usable for a wide variety of contours.

The invention is advantageously implemented according to the embodiments and variants described below, which are to be considered individually or in any technically operative combination.

According to one embodiment, suitable for manual application of the product on the edge of the workpiece, the sleeve consists of a closed-cell polyolefin foam, the cells at the surface thereof being open due to the cutting process of the muff. This embodiment avoids the formation of air bubbles in the product applied during its setting by contact and its application on the edges of the treated part.

According to one embodiment, adapted to an automatic use of the object of the invention, the sleeve consists of an open cell foam, and the rod comprises an orifice for injecting the product applied into the sleeve of foam.

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, especially when the applied product begins to polymerize or is polymerized. The tensioning of the foam sleeve when it is threaded on the rod, ensures its maintenance on the latter, and promotes the setting and the transfer of the applied product, in particular by opening the cells of the foam, on the surface or in any its thickness according to the embodiment. Advantageously, the rod has a protrusion shape for the axial positioning of the sleeve on said rod.

According to an embodiment adapted to a manual use of the object of the invention, the gripping portion is adapted to a grip, the application portion being coaxial with the gripping portion.

According to a particular embodiment, preferably adapted to an automatic use of the tool, the gripping portion is fixed to fixed means in space, and the product is applied by moving the piece relative to the tool .

The invention is explained below according to its preferred embodiments, in no way limiting, and with reference to FIGS. 1 to 5, in which:

FIG. 1 relating to the prior art represents, in a partial sectional view, an example of the result of the edging treatment of the edge of a piece of composite material by means of the tools of the prior art;

- Figure 2 shows an embodiment of a tool object of the invention in a longitudinal sectional view;

- Figure 3 shows in a front view another embodiment of the tool object of the invention;

- Figure 4 is a partial sectional view AA defined in Figure 3, an exemplary embodiment of the application portion;

and FIG. 5 represents, in a front view, an example of the use of the tool which is the subject of the invention in stationary position.

2, according to an exemplary embodiment, preferably but not exclusively adapted to manual use, the tool (200) object of the invention comprises a gripping portion, comprising a handle (210) defining a gripping axis (201) . By way of non-limiting example, 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 bushings (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 that, 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 in rotation relative to the handle (210).

The gripping portion is, according to embodiments adapted to a grip in the case of a tool adapted to a manual application. In this case the diameter of the tubular portion (210) is between 8 mm and 20 mm without these values being limiting, so that said handle is taken in hand in the manner of a pen.

According to exemplary embodiments, the outer form of the tubular portion is not of circular section, but of elliptical, polygonal or other section, for better ergonomics of grip.

The gripping of this gripping portion is, according to one embodiment using an automated edge of the workpiece, performed by a robot by means of a clamp or other effector ensuring such a gripping. By extension it can be fixed by fixing means to a fixed part of the robot, retaining the pivot connection of the shaft (220) and the rod (230) relative to this gripping portion.

In all cases, the rod and the sleeve are in pivot connection axis parallel to the cylindrical axis of the sleeve relative to the gripping portion.

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) terminates in a protrusion form (235), according to this embodiment, by a doubly chamfered shoulder to allow easy installation and removal of a sleeve on the rod.

A tubular foam sleeve (240) is threaded onto said shaft (230) and is stopped and axially positioned thereon against the protrusion form (235). The rod (230) and buffer (240) assembly constitutes the application portion (250) of the tool that is the subject of the invention.

The inner diameter of the foam sleeve (240) when it is 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 maintained on the stem.

By way of non-limiting example, the inside 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 embodiment, constituted of a closed cell foam.

However, the method of cutting the sleeve reveals open cells (241) on its surface. By way of example, the foam used for the sleeve is a polyolefin foam with a density of 29 kg / m ³ closed cell, with a cell average diameter of 0.65 mm.

The foam sleeve is a product application buffer to be applied to the edge of the piece (100). Said product is intended to seal 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 said fibers.

For this purpose, the applied product is a polymerizable product, generally a bicomponent product such as an epoxy resin or sealant. Such products generally have a high viscosity which is further progressive as the polymerization of the product during its open time of application.

In order to achieve this application, in the case of a manual application, said buffer is first loaded in product by contact, by rolling the sleeve, mounted on the tool, on a coated surface of the product to be applied, at the way of a painter's roll. In the case of a bicomponent polymerizable product, the sleeve is loaded with the two components previously mixed.

The product enters the open pores (241) at the surface of the sleeve, by capillarity, without creating air bubbles. Once the sleeve coated, the product is deposited on the edge of the workpiece (100) to be treated by rolling the sleeve on said edge under a slight pressure.

The product is thus uniformly deposited on the edge of the piece without creating an air bubble and without creating a bead. The coaxial positioning of the axis of rotation of the sleeve and the axis of orientation of the grip provides a fine control of the pressure exerted during the application of the product and the path followed with the tool.

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

Advantageously, the rod (230) is constituted or is coated with a suitable material, such as polytetrafluoroethylene (PTFE), avoiding the bonding of the loaded sleeve of the product applied to said rod and facilitate its replacement.

3, according to another exemplary embodiment adapted to an automated use of the tool object of the invention (300), the latter comprises a gripping part comprising a coupling form (310) with the effector gate of a robot or a machine tool spindle and thereby defining a gripping axis (301). According to this exemplary embodiment, the tool (300) which is the subject of the invention comprises two application parts (352, 353) each in pivot connection, free in rotation, with respect to the gripping portion, along axes (302 , 303) parallel to the gripping axis (301). Each of the application portions is of similar structure to that of the preceding embodiment (FIG. 2) and comprises a PTFE rod on which is threaded a sleeve of tubular foam (342, 343), acting as a buffer of application.

According to this embodiment, the two application parts (352, 353) are of different diameters and make it possible, for example, for one (352) of greater diameter, to treat songs extending over large distances, and for the other (353), of reduced diameter, to treat areas where the edge of the piece follows tight radii of curvature. The selection of one or other of the application parts is effected, according to this embodiment, by a 180 ° rotation of the gripping portion around the gripping axis (301).

As for the previous embodiment (FIG. 2), the application of the product to the edge to be treated is achieved by rolling one or other of the application portions (351, 352) over the edge to be treated. and under a slight radial pressure. According to alternative embodiments, this application is performed while the workpiece is fixed in a suitable mounting and that the robot, the manipulator or the machine tool move the tool relative to the workpiece, or, the workpiece 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.

The loading of the product buffer to be applied is, according to an example of embodiment, obtained as in the case of the manual application by rolling the application part (352, 353) on a coated surface of the product to be applied, this operation being performed by the robot or the manipulator.

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 is injected the product to be applied at a controlled rate. Product injection is performed, for example, by means of a peristaltic pump (not shown) or any other means to prevent the creation of air bubbles in the product during said injection.

In the case where the applied product is a two-component product, said components have been mixed before injection.

In this case, the sleeve consists of an open cell foam, to allow the flow of the injected product to the outer surface of the sleeve (342, 343). The principle of application of the product on the workpiece remains the same.

Figure 5, according to another example of implementation, the gripping portion (510) of the tool (500) object of the invention is fixed to a fixed position. The characteristics of the application portion (550) remain the same, with means for injecting the product to be applied under the foam sleeve as shown in FIG. 4, and a sleeve consisting of an open cell foam. The application principle of the product remains the same but is obtained by moving the workpiece, for example by means of a robot, relative to the application portion (550). Alternatively, the workpiece is moved manually facing the tool (500) stationary.

The above description and the exemplary embodiments show that the invention achieves the intended purpose, and makes it possible to simplify the process of edge-edging the edges of a piece made of a composite material with fiber reinforcement, while improving the quality. . Thus, compared to the techniques of bordering using the tools of the prior art, such as brush or roller model, the use of the tool object of the invention, in its manual version, can significantly reduce the time of the border operation, reducing the application time and eliminating scraping operations. Indeed, it is noted that use of the tool object of the invention virtually eliminates the need for scratching operations of the bead, thereby also reducing the risk of accident at work during this operation. The adaptation of the staff is also very fast and the training time is reduced. In automatic operation, the programming is simplified and allows to use, for example, the trajectories generated for the routing programs of the milling part, by simply changing the tool offset values.

Claims

A tool (200, 300, 500) adapted for manual or automatic application of a polymerizable sealant to the edge of a composite workpiece (100), which tool comprises:

at. a gripping portion (210, 310, 510), fixed, defining an orientation axis (201, 301) of the grip;

b. an application portion (250, 352, 353, 550), in pivot connection with the gripping portion, along an axis (302, 303) parallel to the orientation axis (301, 301) of the grip, and free in rotation with respect to the gripping portion and comprising a rod (230, 430) extending along the axis of rotation (201, 302, 303) of the connection;

vs. characterized in that it comprises a cylindrical applicator pad (240, 342, 343) consisting of a tubular foam sleeve (240, 342, 343) threaded onto the stem (230, 430), consisting of a foam polyolefin composition comprising open cells (241) on the surfaces of the sleeve, able to absorb a product and deposit it on a surface by contact with said surface.

A tool according to claim 1 adapted for manual application of the sealant, wherein the foam of the sleeve (230) comprises open cells (241) at the surface and cells closed in the thickness of the sleeve.

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

4. Tool according to claim 1, wherein the outer surface of the rod in contact with the sleeve is made of polytetrafluoroethylene (PTFE) and its outer diameter is greater than the inside diameter of the tubular sleeve.

5. Tool according to claim 1, wherein the rod has a protrusion shape (235) for axial positioning of the sleeve on said rod.

6. Tool according to claim 2, wherein the gripping portion (110) is adapted to a grip, the application portion (250) being coaxial with the gripping portion.

The tool of claim 3, wherein the grip portion (1 10,

310) is adapted to a grip by a robot or a manipulator.

8. Tool (500) according to claim 3, wherein the gripping portion

(510) is fixed to fixed means in space, and where the application of the product is made by moving the workpiece relative to the tool.