Machining device equipped with guiding means and method for creating an opening with such a device

Abstract

The invention relates to a machining device (1) for creating at least one hole (3) in a workpiece (2) made of composite material. The machining device (1) comprises a tool holder (4) and at least one drill bit (5) mounted on the tool holder (4). The drill bit (5) is 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) is intended to bear against the workpiece (2) during the creation of the hole (3), and the drill bit protrudes from the guide body (20). Figure for the abstract: Fig. 1

Description

Title of the invention: MACHINING DEVICE EQUIPPED WITH GUIDING MEANS AND METHOD FOR CREATING AN ORIFICE WITH SUCH A DEVICE Technical field of the invention

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

[0002] Certain turbomachines, particularly longitudinal-axis, dual-flow turbomachines, are equipped with one or more acoustic panels that reduce noise. These acoustic panels are sandwich structures consisting of an acoustic skin (generally a multi-perforated skin), a honeycomb core, and a solid skin. The acoustic skin is generally in contact with the airflow passing through the turbomachine so as to attenuate the noise generated by the airflow. The presence of the acoustic perforations increases the roughness of the flow wall as well as the flow pressure losses.

[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. The drilling can be carried out manually, using a numerical control system, or by a multi-spindle drilling robot.

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

[0005] Pressure losses can, on the contrary, be limited by reducing the diameter of the orifices. The reduced diameter can be, for example, 0.3 mm. This diameter is significantly smaller than what is currently used on acoustic panels mounted in turbomachine nacelles, or even aircraft nacelles. Indeed, a drill bit with such a small diameter can be very sensitive to its angle of attack on the acoustic panel and can break at the slightest deviation caused by its orientation or slippage. A "rebound" effect that occurs after the drill bit has passed through the acoustic panel can also cause the drill bit to break. In particular, once Once the hole is drilled, the acoustic panel, under stress during the drilling process, returns to its initial position, potentially creating lateral force on the drill bit and causing it to break. Mechanical clamping elements installed around the perimeter of the acoustic panel can minimize this rebound. However, mechanical clamping elements are less effective for large pieces, given the numerous areas to be drilled and their varying locations. A similar drawback exists with a vacuum clamping table. Another type of clamping method involves applying adhesive tape to the panel to be drilled. However, the adhesive tape 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 that improves the performance of a machining device while reducing pressure losses on a workpiece drilled with such a device.

[0008] We achieve this objective in accordance with the invention by means of a machining device for making at least one hole in a part made of composite material, the machining device comprising a tool holder and at least one drill mounted on the tool holder, the drill being intended to be driven in rotation around 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, the guide body being intended to bear against the part during the making of the hole and the drill being protruding from the guide body.

[0009] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the guide body allows, on the one hand, for holding and guiding the drill bit in position, and on the other hand, for limiting or even eliminating the rebound effect that occurs when the workpiece has been drilled. The guide body allows for the application of force to the workpiece during the drilling of a hole. In this way, it is possible to drill small diameter holes, which will reduce pressure losses. This solution also offers economic advantages since there is less drill bit breakage and time savings thanks to reduced maintenance.

[0010] The machining device also includes 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 a metallic alloy tallique.

[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 portion for guiding the drill and a portion dust extraction ports which are arranged along the axis of rotation.

[0015] - the guiding portion has an internal diameter that is smaller than the diameter internal of the suction portion).

[0016] - the guide body comprises a first suction portion and a second suction portion, the guidance 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 formed 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 in relation to the tool holder and the drill bit, at least a portion of the guide body being guided in the tool holder and in that it includes an elastic return element which is configured to keep a second surface of the guide body in contact or under pressure with a cutting surface of the workpiece.

[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 and second ends of the guide body, the intermediate piece being made of a different material than that of the guide body.

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

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

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

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

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

[0025] The invention also relates to a method for machining a part made of composite material, comprising the following steps: - supply of a part made of 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 process, 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 objects, details, features and advantages thereof will become more apparent upon reading the following detailed explanatory description, of embodiments of the invention given by way of purely illustrative and non-limiting examples, with reference to the accompanying schematic drawings in which:

[0028] - Figure 1 illustrates an axial cross-section of an example of a machining device intended to to create a through hole in a part according to the invention;

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

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

[0031] - Figure 4 is a cross-sectional view of a component of the guiding device according to [Fig.3];

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

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

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

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

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

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

[0038] Figure 1 partially represents a machining device 1 for a part 2 made of composite material. The machining device 1 is intended to make at least one hole 3 in the part 2 made of composite material.

[0039] The composite material comprises densified reinforcing fibers in a matrix. The fibrous reinforcement is achieved by weaving, layering plies with fibers oriented in different directions, or by forming several plies of fibers pre-impregnated with a resin. The reinforcing fibers may be carbon, glass, ceramic, Kevlar®, polyamide, etc., or a mixture of these fibers. Advantageously, but not exclusively, the fibers are carbon.

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

[0041] The composite material part 2 may be a turbomachine component, 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 as an "open rotor" or "unducted fan"), or a turboshaft engine.

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

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

[0044] With reference to [Fig. 1], the machining device 1 comprises a tool holder 4 and a machining accessory 5. The machining accessory is intended for drilling a wall and is in this case a drill bit. The tool holder 4 is intended to be mounted on the arm of a robot, in particular a 5-axis 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 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 translation, moving away from or towards the workpiece 2 to be drilled. Advantageously, the tool holder 4 can be equipped with a mechanical sliding system enabling this movement.

[0046] The drill 5 extends along an axis of rotation 10. The drill 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 5.

[0047] The machining device 1 comprises, for this purpose, a drive system 11 for rotating the drill bit 5. The drive system 11 includes a motor 12, which is shown schematically in [Fig. 1]. The drive system 11 includes a drive shaft (not shown) which is coupled on one side to the motor 12 and on the other side to the drill bit 5. The tool holder 4 allows the drill bit 5 to be held coaxially 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 sensing means 16 configured to detect and transmit information relating to the position of the tool holder 4 or the drill bit 5. The sensing means 16 may be a presence sensor, a position sensor, a contact sensor, or a combination of these sensors. The sensing means 16 are connected to an electronic control unit 17, shown schematically. This unit is equipped with computing means, memory, and information processing means enabling the machining device 1 to act and / or react according to the information received from the sensing 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 globally circular.

[0051] Generally, the drill bit 5 comprises a first portion 13 which is smooth and a second portion 14 which includes cutting edges or lips 15. In [Fig. 1], the cutting lips 15 are arranged helically around the axis of rotation 10. However, they could be straight or have any other type of shape or arrangement. The cutting lips 15 extend from the first portion 13 to the free distal end 5b. The first portion 13 and the second portion 14 of the drill bit 5 have the same diameter here. Of course, the diameters of the first and second portions 13 and 14 could be different. The proximal end 5a of the drill bit 5 is coupled to the motor 12 via the motor's drive shaft 12. The drill bit 5 is typically secured to the drive shaft by means of a clamping collet (not shown) and a nut (not shown). Other coupling methods may be considered for securing and rotating the drill bit 5.

[0052] The drill bit 5 protrudes 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 a cutting surface 18 of part 2 and to pass through part 2 during the drilling of the hole 3. Advantageously, but not exclusively, the hole 3 passes through the thickness of the wall of part 2 on both sides.

[0054] In the present example, the drill bit 5 is made of a metallic material or a metallic alloy. An example of a metallic material is steel. Alternatively, the drill bit 5 is made of a ceramic material. The ceramic may be alumina (Al₂O₃) or zirconia (ZrO₂) or a mixture of at least one of these two compounds.

[0055] As illustrated in [Fig. 1], the machining device 1 comprises a guide body 20. The guide body 20 is intended to bear against the workpiece 2 during machining, and in particular during the creation of the hole 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 constant circular cross-section along its axis of revolution 21. Of course, the guide body 20 may have a different cross-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 that opens at the first end 20a and the second end 20b. The guide body 20 is arranged 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 from one side to the other along the axis of revolution 21. Advantageously, but not exclusively, the longitudinal cavity 22 has a circular cross-section. In the embodiment shown, the longitudinal cavity 22 has different diameters.

[0058] With further reference to [Fig. 1], 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 using a magnetic system. The first end 20a and the receiving surface 8 are equipped for this purpose with magnets that are opposite each other and in contact to ensure retention. Alternatively, the fixing is achieved by screwing. For example, the first end 20a has a threaded hole on its external surface that engages with a threaded surface carried by the shoulder 9 of the tool holder 4. In another example, the screwing is achieved by means of quarter-turn fasteners. The fixing can also advantageously, but not exclusively, be achieved by clip-on elements. In this case, the first end 20a of the guide body 20 and the tool holder 4 include additional components 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 workpiece to be drilled. Alternatively, the second end 20b has a curved surface complementary to the attack surface 18 of the workpiece 2.

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

[0061] Advantageously, the guide body 20 is mounted in a removable manner. This allows the guide body 20 to be replaced in case of damage or the drill bit 5 to be replaced with another drill bit 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 canonical. In particular, the guide body 20 is made of a metallic, ceramic, and / or carbide material. Examples of metallic materials include steel, aluminum, bronze, and brass. Hard materials include steel and carbide, while soft materials relative to hard materials include aluminum, bronze, and brass.

[0063] With reference to [Fig. 1], the guide body 20 includes a guide portion 23 for the drill 5. This guide portion 23, as its name indicates, allows the drill 5 to be guided and maintained along its axis of rotation 10 during its rotation, and in particular during drilling of the workpiece 2. The guide portion 23 is located towards the second end 20b of the guide body 20.

[0064] The guide body 20 also includes a suction portion 24 which allows, for example, chips or dust from the workpiece material 2 to be evacuated during machining. This also prevents the drill bit 5 from becoming clogged and the material from overheating.

[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 limitingly, the guide portion 23 has an internal diameter that 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 chips or dust from the cutting surface 18 of the workpiece 2.

[0067] Figure 2 illustrates another embodiment of the guiding device 1. This 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 this example, the guide body 20 slides along its axis of revolution 21. At least a portion of the guide body 20 is guided within the tool holder 4. For this purpose, the tool holder 4 includes 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 designed 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 bit 5 passes through the workpiece 2. The guide body 20 is always in contact with the cutting surface 18 of the workpiece 2.

[0068] Furthermore, an elastic return element 32 is configured to maintain the second end 20b of the guide body 20 in contact or under pressure with the cutting surface 18 of the workpiece 2. The elastic return element 32 is preferably arranged between the guide body 20 and the tool holder 4. Advantageously, but not exclusively, the elastic return element 32 is a compression spring 36. The guide body 20 includes 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 flat here but it could have one or more curvatures as explained previously.

[0069] Figure 3 illustrates another embodiment of the guide device 1. This embodiment differs from that of Figure 1 in that the guide body 20 comprises two suction portions 24, designated 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 more passages 25 formed within 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 installed position). The passages 25 are evenly 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 includes a single suction portion.

[0072] This embodiment also differs from the previous one in that the device of Guide 1 comprises several drills 5. In this example, the drills 5 are spaced apart. The proximal end 5a of each drill 5 is received in a recess in the tool holder 4. Each drill 5 is enclosed or surrounded by a guide body 20. The first end 20a of each guide body 20 is fixed to the tool holder 4, and the second end 20b rests against the workpiece 2. In this way, pressure is applied to the workpiece 2 to prevent it from bouncing. The smaller outer diameter DI of each guide body 20 compared to the outer diameter D2 of the tool holder 4 allows several guide bodies 20 to be arranged side by side.

[0073] Here, each drill bit 5 comprises different diameters. In particular, each drill bit 5 has at its proximal end 5a a first diameter D3 which is larger than a second diameter D4 of the drill bit 5 at its distal end 5b. The first diameter D3 extends along the entire height of the first portion 13, which is smooth and serves to guide the drill bit 5. The second diameter D4 is applied to the second portion 14, which is cutting. Since the diameter of the drill bit 5 at its proximal end 5a is larger, this allows for greater rigidity in each drill bit 5. Of course, at least one of the drill bits 5 could have only one diameter along its entire length.

[0074] According to an advantageous, but not limiting, feature 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 cutting surface 18 which may be convex or concave or which may have different curvatures.

[0075] Advantageously, but not exclusively, the drive system 11 for the drills 5 comprises at least one motor 12. In this 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, each driving 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 includes an intermediate piece 26 which is arranged at one of the first ends 20a and the second end 20b of the guide body 20. The intermediate piece 26 is an added part. The intermediate piece 26 is made of a different material than the guide body 20. It is advantageously fixed to one of the ends 20a, 20b to facilitate its installation. The fixing is achieved, for example, by bonding, welding, shrink fitting, or other suitable means at one of the ends.

[0078] In this embodiment, the intermediate part 26 includes a damping element 27 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 exhibits a high capacity for deformation, compression, and / or damping. Thus, when the tool holder 4 is brought close to the part 2 and the guide body 20 is in contact with the cutting surface 18 of the part 2, each damping element 27 is compressed. The damping element 27 limits the impact of the butting or clamping of the guide body 20 on the part 2.

[0079] Advantageously, but not exclusively, the damping element 27 has an annular shape and is arranged over the entire surface of the first end 20a. This facilitates the mounting of the damping element 27.

[0080] Figure 6 illustrates yet another embodiment. This machining device 1 comprises several drills 5 and several guide bodies 20. Each guide body 20 includes two suction portions 24a, 24b and a guide portion 23 equipped with passages 25. This embodiment differs from the embodiment of Figure 5 in that the intermediate piece 26 includes a washer 28. The washer 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 cutting surface 18 of the workpiece 2 when the hole 3 is being made in the workpiece. Advantageously, the washer 28 is 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 "absorption pad." Furthermore, the 28 puck helps to improve the reduction, or even eliminate, 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] Figure 7 illustrates yet another embodiment of a machining device 1. This machining device 1 comprises several drills 5 and several guide bodies 20 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 Figures 5 and 6 in that the intermediate part 26 comprises a sealing element 29. The latter is intended to be arranged between the part 2 and the second end 20b of each guide body 20. The sealing element 29 provides a bearing area that can absorb incidence defects (normality defects) between the attack surface 18 of the workpiece 2 and the guide body 20. In addition, the sealing element 29 allows for damping of the tool holder 4 equipped with the drills 5 and reduces the slippage of the assembly (tool holder and drill(s)) during the phase of bringing the machining device 1 into contact with the workpiece to be drilled.

[0082] Advantageously, the sealing element 29 is an annular seal or an O-ring centered on the axis of rotation 10. The sealing element 29 can be made, for example, of polymer, rubber, or elastomer. This sealing element can withstand pressure and compression. Moreover, such a sealing element 29 can be easily replaced during maintenance 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 various 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 to guide the drill 5 during its rotation and to limit friction between the guide body 20 and the drill 5. Advantageously, but not exclusively, the guide elements 30 are made of a material different from that of the guide body 20. In this embodiment, the guide elements 30 include a ring 31. This ring is centered on the axis of rotation 10 and is positioned at the guide portion 23 of each guide body. More specifically, the ring 31 is fixed to the radially internal surface 23a of the guide portion 23. Advantageously, the fixing is achieved by means of welding, a ferrule, adhesive, crimping, or any other suitable means. Ring 31 is made of a metallic material such as brass or bronze.Alternatively, the ring 31 could be made of a polymer material such as polytetrafluoroethylene (PTFE). The drill bit 5 slides and rotates inside the ring 31. During the movements of the drill bit, it rubs against the ring 31.

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

[0086] In an alternative embodiment shown in one of the drills 5 of [Fig. 7], the machining device 1 includes a lubrication system 35 designed to reduce friction and heating of the drill 5 that 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 bit 5 and the radially internal surface 23a of the guide portion 23. Only one guide body 20 equipped with the lubrication system 35 is shown in [Fig. 7], but all guide bodies 20 can be equipped with it. Advantageously, the lubrication system 35 includes holes (not shown) that open onto the radially internal surface 23a. The holes are connected to a lubricant supply for the lubrication system.

[0087] In another embodiment shown on one of the drills 5 of [Fig.7], the machining device 1 includes 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 various 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 process 100 includes a step of supplying 110 a part 2 made of composite material to be drilled. This part can be, for example, a monolithic skin or a sandwich structure (for example, formed of two skins bonded to a honeycomb).

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

[0092] The supply step 120 includes a substep 121 of mounting the guide body 20 onto the tool holder 4. For this purpose, the drill(s) 5 already mounted on the tool holder 4 are engaged inside the guide body 20. After the guide body 20 is installed, the drill 5 protrudes from it since the length of the guide body 20 is less than that of the drill 5. This difference in length allows the drill 5 to drill the workpiece 2 without obstruction. In other words, the drill 5 protrudes from the guide body 20 both before and after machining the workpiece 2.

[0093] The supply step 120 may include a substep 122 of mounting the tool holder 4 onto the portable machine or robotic arm.

[0094] The method 100 further comprises a step 130 of creating at least one hole in the workpiece using the drill(s) 5. During this step, the tool holder 4 is moved towards the workpiece 2 so that the distal end 5b of the drill 5 is in contact with the cutting surface 18 of the workpiece. The drill 5 is rotated about its axis of rotation 10 by starting the portable machine or 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 near the part 2, a command to slow down the approach of the tool holder 4 is sent to the motor 12.

[0096] The drill bit 5 starts drilling the part until the first end 20b of the guide body 20 is 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 piece 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 and then the intermediate piece 26 is compressed to slow down the approach of the tool holder.

[0099] The guide body 20 surrounding the drill bit 5 and pressed against the workpiece 2 during machining reduces the breakage rate of the drill bit(s) 5 and increases productivity for holes with 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 influences the sliding of the drill bit 5, which can occur when it begins to drill the workpiece 2, and the pressure applied to the workpiece 2 to prevent rebound as the drill bit 5 exits the material after drilling. Holes with a diameter less than 1 mm reduce pressure losses related, for example, to the acoustic treatment of the workpiece.

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), characterized in that 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).

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 portion guide (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 the guide body (20) extends between a first end (20a) and a second end (20b) along an axis of revolution (21) and in that an intermediate part (26) is arranged at one of the first end (20a) and second end (20b) of the guide body (20), the intermediate part (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 guide bodies (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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