FR3114259A1 - device for collecting dust generated during counter-drilling or boring operations in a structure - Google Patents

Abstract

Device for recovering dust generated during counter-drilling or boring operations in a structure The invention relates to a device (9,11) for recovering dust generated during counter-drilling and/or boring operations through-holes (8) of panels (3, 4a, 4b) of structure (1). The device (9, 11) comprises at least one cup (10) conforming to be positioned on an internal face of the panel (3, 4a, 4b), in line with at least one of the holes (8) made during the drilling operation on the panel (3, 4a, 4b), the cup being in contact with said panel (3, 4a, 4b). Figure for abstract: Fig. 2

Description

device for collecting dust generated during counter-drilling or boring operations in a structure

Domain

The invention relates to a device for recovering dust generated during counter-drilling or boring operations in a structure.

Some constituent structures of an aircraft are in the form of a closed box. Such boxes are composed of side panels and upper and lower panels also called spars. An aircraft turbojet engine mast is typically such a boxed structure. The various constituent panels of the mast must be pierced with holes used, for example, for fixing supports for hydraulic or electrical systems necessary for the operation of the turbojet engine. These holes can have the desired final diameter or a smaller diameter. In the latter case, they are called front holes. These pilot holes must then be counter-drilled before being reamed so that they have the expected final diameter.

• Etape A : perçage des panneaux et longerons d’avant trous débouchant,
• Etape B : assemblage des panneaux et longerons pour former la structure caissonnée,
• Etape C : contre-perçage des avant trous des panneaux et longerons pour mise au diamètre final des avant-trous,
• Etape D : alésage des trous pour finalisation de la mise au diamètre des trous,
• Etape E : démontage des panneaux et longerons pour nettoyage des panneaux,
• Etape F : ré-assemblage final de la structure caissonnée.

The manufacturing process of these boxed structures involves different stages and in particular:

• Stage A: drilling of the panels and longitudinal beams with through-holes,
• Stage B: assembly of the panels and beams to form the boxed structure,
• Stage C: counter-drilling of the pilot holes of the panels and stringers to adjust the final diameter of the pilot holes,
• Step D: reaming the holes to finalize the setting of the diameter of the holes,
• Step E: dismantling the panels and beams to clean the panels,
• Stage F: final re-assembly of the boxed structure.

The tools (drills) used during steps C and D are cooled by a mixture of pressurized air and lubricating oil brought through lubrication channels in the tools. The document FR287204 presents, for example, a tool equipped with such a lubricating device. The purpose of this lubrication is to limit the heating of the drill bit caused by its friction on the material.

During steps C and D and because the pilot holes are through holes, material shavings and lubricating oil splashes are ejected into the box-section structure, polluting the inside of the structure and making final cleaning mandatory in order to remove any trace of internal pollution.

Finally, the panels and beams can be made from the same material or from different materials. For example, the upper spar can be made up of a stack of a layer of carbon composite material and a layer of titanium. In this case, before assembling the panels and beams (step B), it is necessary to install, on the internal faces of the panels and beams, foams or equivalent material to absorb the carbon dust generated by the counter-drilling and/or reaming pilot holes. This installation is performed between step A and step B.

• nécessité d’installation des mousses d’absorption, ce qui augmente le temps de préparation de la structure caissonnée et de nettoyage en fin de processus,
• imprégnation des mousses par huile de lubrification et poussières de carbone, rendant les mousses inflammables par une étincelle provoquée par le frottement du foret sur la matière lors du contre-perçage ou de l’alésage.

Prior art back-drilling or reaming operations have the following disadvantages:

• need to install absorption foams, which increases the preparation time of the boxed structure and cleaning at the end of the process,
• impregnation of the foams by lubricating oil and carbon dust, making the foams flammable by a spark caused by the friction of the drill on the material during counter-drilling or reaming.

It could be envisaged to install a suction device or an extinguishing device inside the boxed structure, but this additional operation would make the manufacturing process even more complex, both at the level of the installation of such devices only at the level of the complexity of the devices themselves.

SUMMARY

An object of the present invention is to solve all or part of the drawbacks of the prior art mentioned above

The object of the present invention is in particular to provide a solution to these problems. It relates to a device for recovering dust generated during operations of counter-drilling and/or boring of through-holes of panels of box-section structure, said device being remarkable in that it comprises at least one cup conforming to be positioned on an internal face of the panel, in line with at least one of the holes made during the drilling operation on the panel, the cup being in contact with said panel.

Such a device makes it possible to eliminate the internal pollution resulting from the counter-drilling or reaming of through-holes or pre-holes thanks to the recovery of dust due to their counter-drilling and/or reaming. Thanks to this device, we observe a better evacuation of the polluting elements (chips of material, carbon dust and lubricating oil) because the pressurized air used for the lubrication of the drilling or boring tool is blocked by the presence of the cup and is returned to the outside of the structure, evacuating with it the polluting elements generated by the counter-drilling and/or the bore. It is also observed that the drilling or boring tools are better cooled, the lubricating oil stagnating longer in the hole before being evacuated outside the hole or the pilot hole. This has the effect of increasing the life of the tools. Finally, the presence of the cup prevents chips and lubricating oil (possibly carbon dust) from falling inside the boxed structure. The cleaning operation following step E of the prior art is then no longer necessary. In the case of the presence of carbon composite material, it is no longer necessary to install foam beforehand to absorb the carbon dust generated by the counter-drilling and/or the reaming. The counter-drilling and/or reaming process is therefore simplified and faster.

• la coupelle est intégrée sur une première face d’une plaque perforée, en vis-à-vis d’au moins une perforation de ladite plaque, la seconde face de la dite plaque étant apposée directement contre la face interne lors de l’opération de contre/perçage et/ou d’alésage ;
• la coupelle comprend un rebord recouvert d’un matériau adhésif ;
• la plaque comporte au moins un bras flexible ajustable sur lequel est fixée la coupelle ;
• la plaque comprend une face recouverte d’un matériau adhésif ;
• La plaque est réalisée dans un matériau en caoutchouc ;
• la plaque comporte des découpes pour faciliter sa mise en place ou son retrait.

According to particular embodiments, the device comprises other remarkable characteristics taken separately or in combination:

• the cup is integrated on a first face of a perforated plate, facing at least one perforation of said plate, the second face of said plate being affixed directly against the internal face during the operation of counter/drilling and/or boring;
• the cup comprises a rim covered with an adhesive material;
• the plate comprises at least one adjustable flexible arm on which the cup is fixed;
• the plate comprises a face covered with an adhesive material;
• The plate is made of a rubber material;
• the plate has cutouts to facilitate its installation or removal.

• Mise en place d’un dispositif selon l’invention, comportant au moins une coupelle,
• Positionnement d’au moins une coupelle en vis-à-vis d’au moins un trou débouchant,
• Contre-perçage et/ou alésage dudit au moins un trou débouchant,
• Retrait dudit dispositif en fin de contre-perçage ou d’alésage.

The invention relates to a method for recovering dust generated during counter-drilling and/or boring operations of through-holes of panels of box-section structure, said method being noteworthy in that it comprises the following steps:

• Installation of a device according to the invention, comprising at least one cup,
• Positioning of at least one cup facing at least one through hole,
• Counter-drilling and/or reaming of said at least one through hole,
• Withdrawal of said device at the end of counter-drilling or boring.

The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended drawings in which:
represents an exploded view of a structure on which a device according to the invention can be applied.
shows an enlarged view of part of the box-section structure shown in Figure 1.
schematically represents a sectional view of a boxed structure panel equipped with a device according to a first embodiment of the invention.
schematically represents a sectional view of the device according to a first embodiment of the invention.
schematically represents a front view of the device according to a first embodiment of the invention;
schematically represents a sectional view of a boxed structure panel equipped with a device according to a second embodiment of the invention;
schematically represents a front view of the device according to a second embodiment of the invention;
schematically represents different stages of a process for recovering the dust generated during operations of counter-drilling and/or boring of through-holes of panels of box-section structure according to the invention.

With reference to , there is shown, in an exploded view, a turbojet engine mast which secures the turbojet engine of an aircraft under its wing. This mast 1 is made up of a primary structure 2, two side panels 3, an upper spar 4a and a lower spar 4b. The primary structure 2 is made of titanium in order to absorb the forces linked to the weight of the turbojet engine as well as the thrust forces which it generates during its operation. The side panels 3, the upper spar 4a and the lower spar 4b are used to close the mast into a box-section structure 1 and serve as a support for the hydraulic and electrical systems necessary for the operation of the turbojet engine. These elements are usually made of titanium, steel or carbon composite material.

The panels 3 and the beams 4a, 4b are pierced with pilot holes or holes for fixing the system supports to which reference has previously been made. When the thickness and the material of the panels 3 and side members 4a, 4b allow it, the holes are made directly to the correct diameter. However, it sometimes happens that the drilling means are not powerful enough to drill the hole directly to the right diameter in a single pass. Under these conditions, the panels and beams are pre-drilled with holes (we then speak of pre-holes) before counter-drilling these pre-holes to the final diameter. This counter-drilling can be carried out by an automatic drilling unit, once all the constituent elements of the mast 1 have been assembled together. A final boring operation is then carried out to finalize the adjustment to the final diameter of the hole.

For the sake of lightening the mast 1, the upper spar 4a can be made of carbon composite material. In this case, the upper part 7 of the upper spar 4a is special in the sense that the pilot holes 8 made in this zone are made both in the carbon composite material of the spar 7 and in the titanium of the upper part 2a of the primary structure 2. Counter-drilling and boring operations are used to finalize the diameter of the pilot holes. Before carrying out these operations, it is necessary to install, on the internal faces of the panels 3 and the longitudinal members 4a, 4b, foams or equivalent material to absorb the carbon dust generated by the counter-drilling or the boring of the holes. . The installation of these foams generates the disadvantages mentioned above.

The device 9 according to the invention makes it possible to dispense with the installation of such foams as well as tedious and long cleaning operations.

The device 9, according to a first embodiment of the invention, is represented on and [Fig. 4]. It comprises a plate 12 comprising a first face 12a, a second face 12b, four cavities 12c. These cavities can open out, in which case a cup 10 is associated with each of the cavities 12c, in order to close the cavity.

In a variant embodiment, the cavity 12c may not open out. In this case, the cup is formed by the wall of the second face 12b of the plate 12.

The number of cups 10 depends on the number of holes 8 drilled in a panel 3, 4a or 4b of the box-section structure 1. It has moreover been shown, on and by way of non-limiting example, 5 cavities 12c into which 5 cups 10 will be integrated.

In order to ensure the position of the plate 12 of the device 9 during all the counter-drilling and/or boring operations, the face 12a of the said plate affixed against the internal face 42 of a panel 4a of box-section structure is covered of an adhesive material. In this way, it remains attached to the place where it was placed, thus ensuring that the cups 10 remain opposite the holes 8.

Plate 12 can be made of a rubber material. Its flexible texture thus allows it to adapt to any geometry of the panel 3, 4a, 4b on which it must be affixed. It is easily manipulated by an operator.

Plate 12 may have notches and protrusions 12d as shown in . These notches and protrusions 12d allow the operator better grip of the plate 12, in particular during its removal. It will then be easier for the operator to unhook the plate 12 from the panel 3, 4a or 4b.

schematically represents the application of the device 9 on a boxed structure panel 1, as in this example the spar 4a. The first face 12a is applied to the internal surface 42 of the spar 4a. The device 9 can obviously be applied to any panel 3, 4a, 4b of a box structure 1.

We specify here that the inner surface 42 of the spar 4a is the surface directed towards the inside of the box-section structure 1. The outer surface 41 is, for its part, the surface of the spar 4a directed towards the outside of the box-section structure 1 .

An operator sets up the device 9 by applying it to the internal surface 42 of the spar 4a. He will ensure that the cups 10 are arranged opposite the holes 8.

When all the necessary devices 9 have been put in place by the operator, the drilling and/or boring tool 14 is positioned and the counter-drilling and/or boring operations can begin.

During these operations, the pressurized air used for the lubrication of the drilling and/or boring tool 14 is sent through the tool 14 and is blocked by the presence of the cup(s) 10 It then evacuates to the outside of the hole 8, outside the structure, at the same time evacuating the polluting elements generated by the counter-drilling or the bore. As a reminder, these polluting elements consist of carbon dust and/or titanium shavings from the material which is removed for the tool 14 as well as the lubricating oil from the said tool.

The shape of the cups provides clearance for tool 14 when it reaches the end of counter-drilling and/or boring. Thus, the tool 14 has the necessary space to complete the operation in progress (counter-drilling and/or reaming) without damaging the cups 10.

Some titanium shavings, carbon dust and lubricating oil may not be evacuated to the outside of the holes 8, in particular at the end of counter-drilling or boring, when the tool 14 reaches the end of its stroke . This has no consequence, these elements being captured by the cups 10. They remain trapped in said cups and are removed at the same time as the device 9, when the latter is removed.

represents a second embodiment of a device 11 in accordance with the invention. In this figure, the elements common to the first embodiment retain the same references.

The device 11 according to the invention comprises a plate 16 comprising a first face 16a and a second face 16b. Cups 10 are fixed on the second face 16b of the plate 16 by means of adjustable flexible arms 16c.

The device 11 is affixed to a boxed structure panel 1, for example the spar 4a. The first face 16a is applied to an internal surface of a panel close to the holes 8. This panel may be the one for which the device 11 is used. It could also be a panel adjacent to or opposite the panel on which the device 11 is affixed, as shown in .

As for the first embodiment, the device 11 can be used on any panel 3, 4a, 4b of a box structure 1.

When the device 11 is applied to the internal surface of the primary structure 2, an operator manipulates the flexible arms 16c so as to arrange the cups 10 opposite the holes 8. The arms 16c are for example composed of a flexible metal tube allowing them to be oriented according to any angular position and height. Thanks to this flexible structure, the arms 16c can bend and unfold quickly to facilitate the installation of the cups 10.

When all the necessary devices 11 have been put in place by the operator, the cups 10 covering all the holes 8, the drilling and/or boring tool 14 is put in place and the operations of counter-drilling and/or or boring can start.

The presence of cups 10 prevents titanium shavings, carbon dust and lubricating oil from penetrating inside the boxed structure 1, thus avoiding pollution of said structure.

The shape of the cups 10 provides clearance for the tool 14 when the latter reaches the end of counter-drilling and/or boring. Thus, the tool 14 has the necessary space to complete the operation in progress (counter-drilling and/or reaming) without damaging the cups 10.

Some titanium shavings, carbon dust and lubricating oil may not be evacuated to the outside of holes 8, in particular at the end of counter-drilling and/or boring. As for the first embodiment of the invention, these elements are captured by the cups 10. They remain trapped in the cups 10 and are removed at the same time as the device 11, when the latter is removed.

In order to ensure the position of the device 11 during all the counter-drilling and/or boring operations, the face 16a of said plate affixed against the internal face of the primary structure panel 2 is covered with an adhesive material. In this way, it remains fixed in the place where it was placed, thus ensuring that the plate 16 remains in position during all the operations of counter-drilling and/or reaming.

This plate 16 can be made of rubber. Its flexible texture thus allows it to adapt to any geometry of the panel 3, 4a, 4b on which it must be affixed. It is easily manipulated by an operator.

The plate 16 may have notches and protrusions 16d similar to the notches and protrusions 12d of the plate 12 of the first embodiment ( ). These notches and protrusions 16d allow the operator better grip of the plate 16, in particular during its removal. The operator can more easily unhook the plate 16 from the panel 3, 4a or 4b.

In order to ensure that the cups 10 remain positioned vis-à-vis the holes 8 during all counter-drilling and/or boring operations, the cups comprise a rim 10a which can be covered with an adhesive material . The cups will therefore remain in place regardless of the movements (vibrations for example) applied to the panels.

Finally, the invention relates to a method 18 for recovering dust generated during counter-drilling operations and/or boring of through-holes of panels of box-section structure shown in .

The method 18 comprises a first step of positioning E1 of a device 9, 11 on the internal surface 42 of a panel 3, 4a, 4b of a boxed structure 1. The second step corresponds to the positioning E2 of at least one cup 10 facing at least one hole 8. This step E2 can be performed simultaneously with step E1 if the device according to the invention corresponds to the first embodiment. Indeed, the positioning of the plate 12 causes the automatic positioning of the cups 10 vis-à-vis the holes 8. As regards the second embodiment, an operator will have to manipulate the flexible arms 16c in order to place them opposite holes 8.

When all the cups 10 have been placed opposite the holes 8 requiring a recovery of their diameter, step E3 of counter-drilling and/or boring is launched.

Finally, when all the counter-drilling and/or reaming operations have been carried out, the operator can proceed to step E4 of removing the device 9, 11.

The example that has been given relates to a turbojet mast 1 comprising an upper spar 4a made of carbon composite material. However, the method according to the invention applies to all boxed or non-boxed structures in which counter-drilling or boring operations are necessary, whatever the material of the panels.

Claims (9)

Device (9,11) for suppressing the internal pollution generated by the counter-drilling and/or the boring of through-holes (8) of the panels (3, 4a, 4b) of the structure (1), characterized in that it comprises at least one cup (10) compliant to be positioned on an internal face of the panel (3, 4a, 4b), in line with at least one of the holes (8) made during the drilling operation on the panel (3 , 4a, 4b), the cup being in contact with said panel (3, 4a, 4b). Device (9, 11) according to Claim 1, characterized in that the at least one dish (10) is integrated on a first face (12b) of a perforated plate (12), facing at least a cavity (12c) of said plate (12), the second face (12a) of said plate being affixed directly against the internal face of the panel (3, 4a, 4b) during the counter/drilling operation and/or bore. Device (9, 11) according to Claim 1, characterized in that the at least one cup (10) is fixed to a plate (16) by means of an adjustable flexible arm (16c). Device (9,11) according to claim 1 or 3 characterized in that the cup (10) comprises a rim (10a) covered with an adhesive material. Device (9,11) according to Claim 5 or 6, characterized in that the plate (12, 16) is affixed against an internal face of at least one panel (3, 4a, 4b) of the structure (1). Device (9,11) according to claim 2, 3, 4 or 5 characterized in that the face (12a, 16a) of the plate (12, 16) affixed against the internal face of at least one panel (3, 4a , 4b) of the structure (1) is covered with an adhesive material. Device (9,11) according to claim 2, 3, 4, 5 or 6 characterized in that the plate (12, 16) is made of a rubber material. Device (9,11) according to claim 2, 3, 4, 5, 6 or 7 characterized in that the plate (12, 16) has cutouts (12d, 16d) to facilitate the fitting or removal of the plate (12, 16). Method for recovering dust generated during counter-drilling and/or boring operations of through-holes (8) of panels (3, 4a, 4b) of structure (1), characterized in that it comprises the following steps :

• Positioning (E1) of a device (9, 11) according to any one of Claims 1 to 8,
• Positioning (E2) of the at least one cup (10) facing at least one through hole (8),
• Counterbore and/or bore (E3) of said at least one through hole (8),
• Withdrawal (E4) of said device (9, 11) at the end of counter-drilling and/or boring.