MACHINING DEVICE EQUIPPED WITH GUIDE MEANS AND METHOD FOR PRODUCING AN ORIFICE WITH SUCH A DEVICE

Abstract

The invention relates to a machining device (1) for producing at least one orifice (3) in a part (2) made of composite material, the machining device (1) comprising a tool holder (4) and at least one drill bit (5) mounted on the tool holder (4), the drill bit (5) being intended to be driven in rotation about an axis of rotation (10). According to the invention, the machining device (1) comprises a cylindrical guide body (20) coaxial with the axis of rotation (10), mounted on the tool holder (4), and surrounding the drill bit (5), the guide body (20) being intended to bear on the part (2) during the production of the orifice (3) and the drill bit projecting from the guide body (20). Figure for abstract: Fig.1

Description

Title of the invention: MACHINING DEVICE EQUIPPED WITH GUIDE MEANS AND METHOD OF PRODUCTION OF AN ORIFICE WITH SUCH A DEVICE Technical field of the invention

[0001] The present invention relates to a machining device for producing at least one orifice in a part, such as an aircraft turbomachine part. The invention also relates to a method for producing an orifice in a part using such a machining device. Technological background

[0002] Certain turbomachines, in particular double-flow turbomachines with a longitudinal axis, are equipped with one or more acoustic panel(s) which allow noise reduction. These acoustic panels are sandwich structures formed of an acoustic skin (generally a multi-perforated skin), a cellular core in the form of a honeycomb and a solid skin. The acoustic skin is generally in contact with the air flow which passes through the turbomachine so as to attenuate the noise generated by the air flow. The presence of the acoustic orifices increases the roughness of the wall of the vein as well as the pressure losses of the vein.

[0003] Each hole is made by drilling using a drill bit for example. The drill bit generally has a diameter between 1.4 and 2.6 mm. Drilling can be done manually, using a numerical control or by a multi-spindle drilling robot.

[0004] The pressure drop induced by the presence of acoustic orifices depends in particular on the diameter of the orifices and the porosity (density of orifices) of the acoustic skin. All other things being equal, increasing the diameter of the orifices induces an increase in pressure drops and porosity. However, the porosity of the acoustic skin is dictated by the acoustic performance. Reducing the porosity of the acoustic skin cannot actually reduce pressure drops.

[0005] On the contrary, pressure losses can be limited by reducing the diameter of the orifices. The reduced diameter can be, for example, 0.3 mm. This diameter is much smaller than what is currently used on acoustic panels mounted in turbomachine nacelles, or even aircraft. Indeed, the drill with such a reduced diameter can be very sensitive to the angle of attack of the latter on the acoustic panel and can break at the slightest deviation which can occur by its orientation or by its sliding. A "rebound" effect which takes place after the drill has passed through the acoustic panel can also cause the drill bit to break. In particular, once the hole is drilled, the acoustic panel, constrained during the drilling phase, returns to its initial position, which can create a lateral force on the drill bit and cause it to break. Mechanical clamping elements installed around the perimeter of the acoustic panel can minimize the rebound of the acoustic panel. Mechanical clamping elements have the disadvantage in the case of a large part of being ineffective in dealing with the many areas to be drilled and their locations. The same type of disadvantage occurs with a vacuum clamping table. Another type of clamping is the installation of an adhesive strip on the panel to be drilled. However, the adhesive strip tends to stick to the drill bit and cause it to break.

[0006] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0007] The objective of the present invention is to provide a simple, economical and robust solution which makes it possible to improve the performance of a machining device while making it possible to reduce the pressure losses on a part drilled with such a device.

[0008] We achieve this objective in accordance with the invention by means of a machining device for producing at least one orifice in a part made of composite material, the machining device comprising a tool holder and at least one drill bit mounted on the tool holder, the drill bit being intended to be driven in rotation about an axis of rotation, the machining device comprising a cylindrical guide body coaxial with the axis of rotation, mounted on the tool holder, and surrounding the drill bit, the guide body being intended to bear on the part during the production of the orifice and the drill bit projecting from the guide body.

[0009] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the guide body makes it possible, on the one hand, to hold the drill bit in position and guide it, and on the other hand to limit or even cancel the rebound effect which appears when the part has been drilled. The guide body makes it possible to apply a force to the part while making an orifice. In this way, it is possible to drill orifices of small diameters which will reduce pressure losses. This solution also presents an economic gain since there is less drill bit breakage and a time saving thanks to the reduction in maintenance.

[0010] The machining device also comprises one or more of the following features, taken alone or in combination:

[0011] - the guide body has a length less than a length of the drill.

[0012] - the guide body is made of metallic material or of an alloy metallic.

[0013] - the tool holder has at least one circular cross-section and the body of guide has an external diameter equal to or less than the external diameter of the tool holder.

[0014] - the guide body comprises a drill guide portion and a portion dust extraction which are arranged along the axis of rotation.

[0015] - the guide portion has an internal diameter which is less than the diameter internal of the suction portion).

[0016] - the guide body comprises a first suction portion and a second suction portion, the guide portion being located between the first suction portion and the second suction portion along the axis of rotation.

[0017] - the guide body comprises a plurality of passages arranged in a thickness of the guide portion and extending along the axis of rotation, each passage opening into at least one suction portion.

[0018] - the guide body is movable in translation along its axis of revolution by relative to the tool holder and the drill, at least a portion of the guide body being guided in the tool holder and in that it comprises an elastic return member which is configured so as to maintain a second surface of the guide body in contact or in pressure with a leading surface of the part.

[0019] - the guide body extends between a first end and a second end along an axis of revolution and in that an intermediate piece is arranged at one of the first end and second end of the guide body, the intermediate piece being made of a material different from that of the guide body.

[0020] — the intermediate part is chosen from the group comprising an element damping, a washer and a sealing member.

[0021] - a guide ring is arranged at the guide portion.

[0022] - a lubrication system is arranged in the guide portion.

[0023] - the machining device comprises several drills which are mounted on the tool holder and which are spaced from each other, several guide bodies being arranged so as to respectively surround a drill bit.

[0024] - the machining device comprises a motor intended to drive one or more drills.

[0025] The invention also relates to a method of machining a part made of composite material, comprising the following steps: - supply of a part in composite material, - supply of a machining device having any of the above characteristics, and - making at least one hole in the part using at least one drill bit.

[0026] According to the method, the composite material comprises carbon fibers and an epoxy-based resin. Brief description of the figures

[0027] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0028] - [Fig.l] illustrates an axial section of an example of a machining device intended for making a through hole in a part according to the invention;

[0029] - [Fig.2] illustrates in axial section another embodiment of a machining device equipped with a movable guide member according to the invention;

[0030] - [Fig.3] represents, in an axial section, another embodiment of a machining device equipped with several machining accessories according to the invention;

[0031] - [Fig.4] is a cross-sectional view of a member of the guide device according to [Fig.3];

[0032] - [Fig.5] illustrates yet another embodiment of a machining device equipped with several machining accessories according to the invention;

[0033] - [Fig.6] illustrates yet another embodiment of a machining device equipped with several machining accessories according to the invention;

[0034] - [Fig.7] is an axial sectional view of another embodiment of a machining device equipped with several machining accessories according to the invention;

[0035] - [Fig.8] is a cross-sectional view AA of a member of the device machining according to [Fig.7]; and,

[0036] - [Fig.9] represents a flowchart of a machining process for a part in composite material. Detailed description of the invention

[0037] In the following description, elements which are identical or substantially identical and / or with the same functions are represented by the same numerical references.

[0038] [Fig.l] partially represents a machining device 1 for a part 2 made of composite material. The machining device 1 is intended to produce at least one orifice 3 in the part 2 made of composite material.

[0039] The composite material comprises reinforcing fibers densified in a matrix. The fiber reinforcement is made by weaving, superimposing sheets with fibers oriented in different directions, or is made from several plies of fibers pre-impregnated with a resin. The reinforcing fibers may be carbon fibers, glass, ceramic, Kevlar®, polyamide, etc. or a mixture of these fibers. Advantageously, but not limited to, the fibers are made of carbon.

[0040] The matrix is ​​preferably an organic matrix and may be a thermoplastic resin or a thermosetting resin. The resin may advantageously be an epoxy-based resin. In the present description, the terms "resin" and "matrix" are equivalent.

[0041] The part 2 made of composite material may be a turbomachine part which is not shown. The turbomachine is intended to be mounted on an aircraft such as an airplane. The turbomachine may be a turbojet such as a turbofan, a turboprop equipped with at least one unducted propeller (known by the English expression “open rotor” or “unducted fan”) or a turboshaft engine.

[0042] An example of a part 2 made of composite material for a turbomachine is an acoustic panel centered around a longitudinal axis of the turbomachine. The acoustic panel can equip a fan casing or a nacelle of the turbomachine.

[0043] Of course, the part 2 made of composite material with through holes obtained by drilling can be another part of a turbomachine or can even be applicable to other types of field, for example automotive.

[0044] With reference to [Fig.l], the machining device 1 comprises a tool holder 4 and a machining accessory 5. The machining accessory is intended to drill a wall and is here a drill bit. The tool holder 4 is intended to be mounted on an arm of a robot, in particular a 5-axis type robot (not shown).

[0045] The tool holder 4 has a generally cylindrical shape with an axis of revolution 6. The tool holder 4 comprises an external cylindrical surface 7 which is connected to a receiving surface 8. The latter is defined in a plane which is perpendicular to the axis of revolution 6 of the tool holder 4. The receiving surface 8 is delimited by an annular shoulder 9 centered on the axis of revolution 6. The tool holder 4 moves in a translational movement away from or towards the part 2 to be drilled. Advantageously, the tool holder 4 can be equipped with a mechanical slide system allowing this movement.

[0046] The drill bit 5 extends along an axis of rotation 10. The drill bit 5 is mounted in rotation, along the axis of rotation 10, on the tool holder 4. The tool holder 4 is fixed in this case relative to the drill bit 5.

[0047] The machining device 1 comprises for this purpose a drive system 11 for rotating the drill 5. The drive system 11 comprises a motor 12 which is shown schematically in [Fig.l]. The drive system 11 comprises a drive shaft (not shown) which is coupled on the one hand to the motor 12 and on the other hand to the drill 5. The tool holder 4 makes it possible to keep the drill 5 coaxial with the axis of rotation of the motor 12.

[0048] The drive system 11 with the motor 12 can alternatively be integrated into the tool holder 4 as shown in [Fig. 3]. According to another alternative, the motor 12 is arranged in the robotic arm.

[0049] Advantageously, the tool holder 4 is equipped with detection means 16 which are configured to detect and transmit information relating to the position of the tool holder 4 or the drill 5. The detection means 16 may be a presence sensor, a position sensor, a contact sensor or a combination of these sensors. The detection means 16 are connected to an electronic control unit 17 shown schematically. The latter is provided with calculation means, memories, and information processing means allowing the machining device 1 to act and / or react according to the information received from the detection means 16. The electronic control unit 17 may be mounted in the tool holder 4 or in the robotic arm. The motor 12 may be connected to the electronic control unit 17.

[0050] The drill 5 extends in particular between a proximal end 5a and a distal end 5b. The drill 5 has a cross-section to the axis of rotation 10 which is here circular or generally circular.

[0051] Generally, the drill 5 comprises a first portion 13 which is smooth and a second portion 14 which comprises cutting edges or lips 15. In [Fig.l], the cutting lips 15 are arranged in a helical manner around the axis of rotation 10. However, these could be straight or have any type of shape or arrangement. The cutting lips 15 extend from the first portion 13 to the distal end 5b which is free. The first portion 13 and the second portion 14 of the drill 5 here have an identical diameter. Of course, the diameters of the first and second portions 13, 14 could be different. The proximal end 5a of the drill bit 5 is coupled to the motor 12 via the drive shaft of the motor 12. The drill bit 5 is typically secured to the drive shaft via a collet (not shown) and a nut (not shown). Other coupling means may be considered for securing and rotating the drill bit 5.

[0052] The drill bit 5 projects from the receiving surface 8. The drive shaft and the drill bit 5 are coaxial. We understand that there is a single motor 12 and a single drill bit 5.

[0053] The distal end 5b is intended to come into contact with an attack surface 18 of the part 2 and to pass through the part 2 during the production of the orifice 3 by drilling. Advantageously, but not limitingly, the orifice 3 passes through the thickness of the wall of the part 2 on either side.

[0054] In the present example, the drill 5 is made of a metallic material or a metallic alloy. An example of a metallic material is steel. In a manner alternatively, the drill 5 is made of a ceramic material. The ceramic may be alumina (A12O3) or Zirconia (Zr02) or a mixture of at least one of these two compounds.

[0055] As illustrated in [Fig.l], the machining device 1 comprises a guide body 20. The guide body 20 is intended to bear on the part 2 during machining, and in particular during the production of the orifice 3. Advantageously, the guide body 20 is cylindrical and is mounted on the tool holder 4. The guide body 20 has an axis of revolution 21 which is coaxial with the axis of rotation 10 of the drill 5. In particular, the guide body 20 extends between a first end 20a and a second end 20b along the axis of revolution 21. The guide body 20 has a section here which is constant circular along its axis of revolution 21. Of course, the guide body 20 may have a different section.

[0056] In the present embodiment, the guide body 20 has an external diameter DI equal to or less than the external dimensions (here diameter D2) of the tool holder 4. This makes it possible not to impact the dimensions of the machining device 1 and to avoid the latter being bulky.

[0057] Advantageously, the guide body 20 is hollow and has a longitudinal cavity 22 which opens at the first end 20a and at the second end 20b. The guide body 20 is arranged so as to surround the drill bit 5. In other words, the drill bit 5 is engaged inside the longitudinal cavity 22 of the guide body 20 and passes through it on either side along the axis of revolution 21. Advantageously, but not limitingly, the longitudinal cavity 22 has a circular section. In the exemplary embodiment, the longitudinal cavity 22 has different diameters.

[0058] Still with reference to [Fig.l], the first end 20a of the guide body 20 is fixed to the receiving surface 8 of the tool holder 4. This fixing can be achieved by means of a magnetic system. The first end 20a and the receiving surface 8 are equipped for this purpose with magnets which are opposite each other and in contact to ensure holding. Alternatively, the fixing is achieved by screwing. For example, the first end 20a comprises a screw thread on its external surface cooperating with a tapped surface carried by the shoulder 9 of the tool holder 4. According to another example, the screwing is achieved by “quarter turn” type elements. The fixing can also be achieved advantageously, but not limited to, by clipping elements. In this case, the first end 20a of the guide body 20 and the tool holder 4 comprise complementary members to achieve this type of fixing.

[0059] The second end 20b has a flat surface in complementary contact with the attack surface 18 of the part to be drilled. Alternatively, the second end 20b has a curved surface complementary to the attack surface 18 of the part 2.

[0060] The guide body 20 has a length L1 less than the useful length L2 of the drill 5. The length L1 of the guide body 20 is measured between the first end 20a and the second end 20b. The useful length L2 of the drill 5 is measured between the receiving surface 8 and the distal end of the drill 5.

[0061] Advantageously, the guide body 20 is mounted in a removable manner. This makes it possible to replace the guide body 20 in the event of damage or to replace the drill 5 with another drill of a different diameter, for example.

[0062] The guide body 20 is made of a so-called “hard” material or a so-called “soft” material. The material of the guide body 20 is hard or soft relative to the material of the drill bit. The material of the drill bit 5 in the present invention is considered to be canonical. In particular, the guide body 20 is made of a metallic, ceramic, and / or carbide material. An example of a metallic material is steel, aluminum, bronze, brass. Hard materials are steel, carbide while soft materials relative to hard materials are aluminum, bronze, or brass.

[0063] With reference to [Fig. 1], the guide body 20 comprises a guide portion 23 for the drill 5. This guide portion 23, as its name indicates, makes it possible to guide the drill 5 and to maintain the drill 5 along its axis of rotation 10 during the rotation thereof and in particular during the drilling of the part 2. The guide portion 23 is located towards the second end 20b of the guide body 20.

[0064] The guide body 20 also comprises a suction portion 24 which makes it possible to evacuate, for example, chips or dust from the material of the part 2 during the machining thereof. This also prevents the drill 5 from becoming clogged and an increase in the temperature of the material thereof.

[0065] The suction portion 24 is located towards the first end 20a of the guide body 20. The suction portion 24 and the guide portion 23 are arranged along the axis of revolution 21 of the guide body 20. In particular, the suction portion 24 opens into the first end 20a while the guide portion 23 opens into the second end 20b.

[0066] Advantageously, but not limitatively, the guide portion 23 has an internal diameter which is smaller than the internal diameter of the suction portion 24. The internal diameter of the guide portion 23 allows better guidance of the drill 5 while the internal diameter of the suction portion 24 allows efficient evacuation of the chips or dust from the attack surface 18 of the part 2.

[0067] [Fig.2] illustrates another embodiment of the guidance device 1. This embodiment embodiment differs from that of figure 1 in that the guide body 20 is movable relative to the drill 5 and also relative to the tool holder 4. In the present example, the guide body 20 slides along its axis of revolution 21. At least a portion of the guide body 20 is guided in the tool holder 4. For this purpose, the tool holder 4 comprises a groove 34 centered on the axis of rotation 10 of the drill 5 and which opens onto the receiving surface 8 of the tool holder 4. The groove 34 is intended to receive at least the first end 20a of the guide body 20. In this way, the guide body 20 moves inside the tool holder 4 as the drill 5 passes through the part 2 to be drilled. The guide body 20 is always in contact with the leading surface 18 of the part 2.

[0068] Furthermore, an elastic return member 32 is configured so as to maintain the second end 20b of the guide body 20 in contact or under pressure with the attack surface 18 of the part 2. The elastic return member 32 is preferably arranged between the guide body 20 and the tool holder 4. Advantageously, but not limitingly, the elastic return member 32 is a compression spring 36. The guide body 20 comprises for this purpose at least one groove 33 in which the compression spring 36 is housed. In the present embodiment, the groove 33 is annular and centered on the axis of revolution 21 of the guide body. A single compression spring 36, centered on the axis of revolution 21, is housed in the groove 33. The compression spring 36 extends between a first end 36a and a second end 36b.The first end 36a is in contact with the bottom of the groove 34 formed in the tool holder 4 and the second end 36b is in contact with the bottom of the groove 33 made in the guide body 20. The attack surface 18 is here flat but it could have one or more curvatures as explained previously.

[0069] [Fig. 3] illustrates another embodiment of the guide device 1. This embodiment differs from that of [Fig. 1] in that the guide body 20 comprises two suction portions 24, called first suction portion 24a and second suction portion 24b. The guide portion 23 is located between the first suction portion 24a and the second suction portion 24b along the axis of revolution 21 of the guide body 20.

[0070] With reference to Figures 3 and 4, the guide body 20 comprises one or a plurality of passages 25 which are arranged in a thickness of the guide portion 23. Each passage 25 extends along the axis of revolution 21 (i.e. along the axis of rotation in the installation situation). The passages 25 are regularly distributed around the axis of revolution 21. Each passage 25 opens into both the first suction portion 24a and the second suction portion 24b. In the example shown, there are four passages 25. However, the number of passages 25 can be between 2 and 8. We can also see that each passage 25 also has a curvature around the axis of revolution 21.

[0071] The passages 25 could also be provided in the guide portion of the guide body 20 which comprises a single suction portion.

[0072] This embodiment also differs from the previous one in that the guide device 1 comprises several drills 5. In this example, the drills 5 are spaced apart from each other. The proximal end 5a of each drill 5 is received in a housing of the tool holder 4. Each drill 5 is enveloped or surrounded by a guide body 20. The first end 20a of each guide body 20 is secured to the tool holder 4 and the second end 20b bears against the part 2. In this way, pressure is applied to the part 2 so as to avoid the effects of rebound thereof. The smaller outside diameter DI of each guide body 20 compared to the outside diameter D2 of the tool holder 4 allows the arrangement of several guide bodies 20 next to each other.

[0073] Here, each drill 5 comprises different diameters. In particular, each drill 5 comprises at its proximal end 5a a first diameter D3 which is greater than a second diameter D4 of the drill 5 at its distal end 5b. The first diameter D3 extends over the entire height of the first part 13 which is smooth and which serves to guide the drill 5. The second diameter D4 is applied to the second part 14 which is cutting. The diameter of the drill 5 at its proximal end 5a being greater, this makes it possible to maintain greater rigidity in each drill 5. Of course, at least one of the drills 5 could have only one diameter along its entire length.

[0074] According to an advantageous, but non-limiting, characteristic of this embodiment, at least one of the drills 5 slides along the axis of rotation 10. Advantageously, each drill 5 slides respectively along the axis of rotation 10 and independently of the other drills 5. Such a configuration allows the drills 5 to adapt to the attack surface 18 which would be convex or concave or which would have different curvatures.

[0075] Advantageously, but not limitatively, the drive system 11 of the drills 5 comprises at least one motor 12. In the present case, it is a single motor 12. Each drill 5 can be coupled directly to the drive shaft via the collet / nut system. Alternatively, the collet / nut system can be provided at the output of a gearbox (not shown). The gearbox would comprise an input connected to the single motor and several outputs rotated by gear sets. Alternatively, the drive system comprises several motors 12 which each drive a drill 5.

[0076] [Fig. 5] illustrates another embodiment of the guide device 1. This guide device 1 comprises several drills 5 and several guide bodies 20. Each guide body 20 comprises two suction portions 24a, 24b and a guide portion 23 equipped with passages 25.

[0077] This embodiment differs from the embodiment of [Fig. 3] in that it comprises an intermediate piece 26 which is arranged at one of the first end 20a and second end 20b of the guide body 20. The intermediate piece 26 is an added piece. The intermediate piece 26 is made of a material different from that of the guide body 20. It is advantageously fixed to one of the ends 20a, 20b so as to facilitate its installation. The fixing is carried out for example by gluing, welding, hooping or other suitable means at one of the ends.

[0078] In this embodiment, the intermediate part 26 comprises a damping element 27 which is arranged between the receiving surface 8 of the tool holder 4 and the first end 20a of each guide body 20. The damping element 27 can be made of an elastomer. Such a material has a high capacity for deformation, compression and / or damping. In this way, when the tool holder 4 is brought close to the part 2 and the guide body 20 is in contact with the leading surface 18 of the part 2, each damping element 27 is compressed. The damping element 27 makes it possible to limit the impact of the guide body 20 being placed in abutment or pressed against the part 2.

[0079] Advantageously, but not limitatively, the damping element 27 has an annular shape and is arranged over the entire surface of the first end 20a. This makes it easier to mount the damping element 27.

[0080] [Fig. 6] illustrates yet another embodiment. This machining device 1 comprises several drills 5 and several guide bodies 20. Each guide body 20 comprises two suction portions 24a, 24b and a guide portion 23 equipped with passages 25. This embodiment differs from the embodiment of [Fig. 5] in that the intermediate part 26 comprises a washer 28. The latter is fixed to the second end 20b of each guide body 20. In other words, the washer 28 is located between the second end 20b and the attack surface 18 of the part 2 when the orifice 3 is made in the part. The washer 28 is advantageously made of an elastic and flexible material. An example of an elastic material is a thermoplastic, a rubber or an elastomer. This washer 28 acts as an “absorbent buffer”. Furthermore, washer 28 makes it possible to improve the reduction, or even the elimination of the rebound effect.Advantageously, but not limitingly, the washer 28 is annular and is centered on the axis of rotation 10. The washer 28 could be arranged at the first end 20a in an alternative manner.

[0081] [Fig. 7] illustrates yet another embodiment of a machining device 1. This machining device 1 comprises several drills 5 and several guide bodies 20 respectively surrounding a drill 5. The drills 5 are mounted or coupled to the tool holder 4. Each guide body 20 comprises two suction portions 24a, 24b and a guide portion 23 equipped with passages 25. This embodiment differs from the embodiments of FIGS. 5 and 6 in that the intermediate part 26 comprises a sealing member 29. The latter is intended to be arranged between the part 2 and the second end 20b of each guide body 20. The sealing member 29 offers a support zone capable of absorbing incidence defects (normality defects) between the attack surface 18 of the part 2 and the guide body 20.In addition, the sealing member 29 allows damping of the tool holder 4 equipped with the drills 5 and to reduce the sliding of the assembly (tool holder and drill(s)) during the phase of bringing the machining device 1 into contact with the part to be drilled.

[0082] Advantageously, the sealing member 29 is an annular seal or an O-ring centered on the axis of rotation 10. The sealing member 29 may be made, for example, of polymer, rubber, or elastomer. This sealing member can withstand pressure and compression. Furthermore, such a sealing member 29 may be easily changed during the maintenance phase of the machining device 1.

[0083] Of course, the machining device 1 comprising a single drill 5 and / or a guide body 20 with a single suction portion 24 can be equipped with an intermediate part 26 as described in the different embodiments above.

[0084] With reference to Figures 7 and 8, the machining device 1 further comprises guide elements 30 for the drill 5. These guide elements 30 are configured so as to guide the drill 5 during its rotation and to limit the friction between the guide body 20 and the drill 5. The guide elements 30 are advantageously, but not limited to, made of a material different from that of the guide body 20. The guide elements 30 comprise in this exemplary embodiment a ring 31. The latter is centered on the axis of rotation 10 and is arranged at the guide portion 23 of each guide body. More precisely, the ring 31 is fixed on the radially internal surface 23a of the guide portion 23. Advantageously, the fixing is carried out by means of welding, a hoop, glue, crimping or any suitable means. Ring 31 is made of a metallic material such as brass, bronze.Alternatively, the ring 31 could be made of a polymer material such as polytetrafluoroethylene (PTFE). The drill 5 slides and rotates inside the ring 31. During the movements of the drill, it rubs against the ring 31.

[0085] Alternatively, the guide elements 30 comprise balls (for example three in number) (not shown) each mounted on a spring fixed to the radially internal surface 23 of the guide portion. The balls are positioned at 120° to each other around the axis of revolution 21.

[0086] In an alternative embodiment which is shown on one of the drills 5 of [Fig. 7], the machining device 1 comprises a lubrication system 35 intended to reduce the friction and heating of the drill 5 which may be in contact with the guide body 20. The lubrication system 35 is arranged in the guide portion 23 of a guide body 20. The lubrication system 35 is arranged more precisely between the drill 5 and the radially internal surface 23a of the guide portion 23. A single guide body 20 equipped with the lubrication system 35 is illustrated in [Fig. 7] but all the guide bodies 20 can be equipped with it. Advantageously, the lubrication system 35 comprises holes (not shown) which open onto the radially internal surface 23a. The holes are connected to a source of lubricant supply to the lubrication system.

[0087] In another variant embodiment shown on one of the drills 5 of [Fig.7], the machining device 1 comprises the lubrication system 35 and the guide elements 30. In this case, the lubrication system 35 is mounted radially inside the guide elements 30.

[0088] Of course, the machining device 1 comprising a single drill and / or a guide body 20 with a single suction portion 24 can be equipped with a lubrication system 35 or guide elements 30 as described in the different embodiments above.

[0089] We will now describe a method 100 for machining a part 2 made of composite material. The method is implemented using the machining device 1 and is shown in [Fig.9].

[0090] The method 100 comprises a step 110 of providing a part 2 made of composite material to be drilled. This part may be, for example, a monolithic skin or a sandwich structure (for example, formed of two skins glued to a honeycomb).

[0091] The method comprises a step 120 of providing the machining device 1. The drill or drills 5 are already mounted on the tool holder 4.

[0092] The supply step 120 comprises a sub-step 121 of placing the guide body 20 on the tool holder 4. For this purpose, the drill bit(s) 5 already mounted on the tool holder 4 are engaged inside the guide body 20. After the installation of the guide body 20, the drill bit 5 projects therefrom since the length of the guide body 20 is less than that of the drill bit 5. The difference in length allows the drill bit 5 to pierce the part 2 without obstacle. In other words, the drill bit 5 projects from the guide body 20 before and after the machining of the part 2.

[0093] The supply step 120 may comprise a sub-step 122 of mounting the tool holder 4 on the portable machine or the robotic arm.

[0094] The method 100 further comprises a step 130 of producing at least one orifice in the part by means of the drill(s) 5. During this step, the tool holder 4 is moved towards the part 2 so that the distal end 5b of the drill 5 is in contact with the attack surface 18 of the part. The drill 5 is rotated about its axis of rotation 10 by starting the portable machine or the robotic arm.

[0095] In the case of a robot equipped with the tool holder 4, when at least one sensor of the detection means 16 determines that the tool holder 4 is close to the part 2, an order to slow down the approach of the tool holder 4 is sent to the motor 12.

[0096] The drill 5 begins to drill the part until the first end 20b of the guide body 20 abuts against the attack surface 18 of the part 2.

[0097] In the case where the intermediate part 26 is placed on the second end 20b of the guide body 20, the intermediate part 26 is brought into contact with the attack surface 18 of the part 2 and is compressed to slow down the approach of the tool holder 4.

[0098] In the case where the intermediate part 26 is placed on the first end 20a of the guide body 20, the second end 20b of the guide body 20 is brought into contact with the attack surface 17 then the intermediate part 26 is compressed to slow down the approach of the tool holder.

[0099] The guide body 20 surrounding the drill 5 and placed in abutment against the part 2 during the machining thereof makes it possible to reduce the breakage rates of the drill(s) 5 and to increase productivity for orifices having very small diameters, i.e. diameters less than 1 mm, preferably between 0.1 mm and 0.5 mm. In this way, the guide body 20 intervenes on the sliding of the drill 5 which can occur when it begins to drill the part 2 and the pressurization of the part 2 to avoid the rebound effect at the exit of the drill 5 from the material after drilling. The orifices with a diameter less than 1 mm make it possible to reduce the pressure losses linked for example to the acoustic treatment of the part.

Claims

Claims

1. Machining device (1) for producing at least one orifice (3) in a part (2) made of composite material, the machining device (1) comprising a tool holder (4) and at least one drill bit (5) mounted on the tool holder (4), the drill bit (5) being intended to be driven in rotation about an axis of rotation (10), the tool holder (4) having a generally cylindrical shape with an axis of revolution (6) and comprising an external cylindrical surface (7) which is connected to a receiving surface (8), the receiving surface (8) being defined in a plane which is perpendicular to the axis of revolution (6) of the tool holder (4) and delimited by an annular shoulder (9) centered on the axis of revolution (6), the drill bit (5) projecting from the receiving surface (8) and the tool holder (4) moving in a translational movement away from or towards the part (2),characterized in that the machining device (1) comprises a cylindrical guide body (20) coaxial with the axis of rotation (10), removably mounted on the tool holder (4), and surrounding the drill bit (5), the guide body extending at least in part from the receiving surface (8) between a first end (20a) and a second end (20b), the guide body (20) being intended to bear on the part (2) during the production of the orifice (3) and the drill bit projecting from the guide body (20).,

2. Machining device (1) according to the preceding claim, characterized in that the guide body (20) has a length (L1) less than a length (L2) of the drill (5).

3. Machining device (1) according to one of the preceding claims, characterized in that the guide body (20) is made of metallic material or of a metallic alloy.

4. Machining device (1) according to one of the preceding claims, characterized in that the tool holder (4) has at least one circular cross-section and the guide body (20) has an external diameter (D1) equal to or less than the external diameter (D2) of the tool holder (4).

5. Machining device (1) according to any one of the preceding claims, characterized in that the guide body (20) comprises a guide portion (23) of the drill bit (5) and a dust suction portion (24) which are arranged along the axis of rotation (10).

6. Machining device (1) according to the preceding claim, characterized in that the guide portion (23) has an internal diameter which is smaller than the internal diameter of the suction portion (24).

7. Machining device (1) according to one of claims 5 and 6, characterized in that the guide body (20) comprises a first suction portion (24a) and a second suction portion (24b), the guide portion (23) being located between the first suction portion (24a) and the second suction portion (24b) along the axis of rotation (10).

8. Machining device (1) according to any one of the preceding claims 5 to 7, characterized in that the guide body (20) comprises a plurality of passages (25) formed in a thickness of the guide portion (23) and extending along the axis of rotation, each passage (25) opening into at least one suction portion (24).

9. Machining device (1) according to any one of the preceding claims, characterized in that the guide body (20) is movable in translation along its axis of revolution (21) relative to the tool holder (4) and to the drill (5), at least a portion of the guide body (20) being guided in the tool holder (4) and in that it comprises an elastic return member (32) which is configured so as to maintain a second surface (20b) of the guide body (20) in contact or under pressure with a leading surface (18) of the part (2).

10. Machining device (1) according to any one of the preceding claims, characterized in that an intermediate piece (26) is arranged at one of the first end (20a) and second end (20b) of the guide body (20), the intermediate piece (26) being made of a material different from that of the guide body (20).

11. Machining device (1) according to any one of claims 5 to 9, characterized in that a guide ring (31) is arranged at the guide portion (23).

12. Machining device (1) according to any one of claims 5 to 11, characterized in that a lubrication system (35) is arranged in the guide portion (23).

13. Machining device (1) according to the preceding claim, characterized in that it comprises several drills (5) which are mounted on the tool holder (4) and which are spaced from each other, several bodies guide (20) being arranged so as to respectively surround a drill (5).

14. Machining device (1) according to any one of the preceding claims, characterized in that it comprises a motor (12) intended to drive one or more drills (5).

15. Method (100) for machining a part (2) made of composite material, comprising the following steps: - providing (110) a part (2) made of composite material, - providing (120) a machining device (1) according to any one of the preceding claims, and - producing (130) at least one orifice (3) in the part (4) by means of the drill (5).

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