Low mass floating nut system and method of joining two parts using said system.

Abstract

- Floating nut system of reduced mass and method for assembling two parts using said system. - The floating nut system 1 being intended to assemble a part (2) and a part (3), the part (2) comprising an opening (4) having an axis of revolution (A1), the floating nut system (1) comprising at least one cage device (6) made of elastomer and a nut device (7), the cage device (6) comprising a cylinder (8) intended to be inserted into an opening (9) made in the part (3) and a crown (11) around the cylinder (8); the nut device (7) comprising a cylinder (13) having an axis of revolution (A3) and a washer (15) intended to press the crown (11) against the part (3) when the screw (5) is screwed into the cylinder (13); the cylinder (8) being configured to deform when screwing the screw (5) so that the axis of revolution (A1) and the axis of revolution (A3) are substantially the same.The elastomer cage device (6) allows to reduce the mass of the floating nut system (1). Figure for abstract: Fig.1.

Description

Title of the invention: Reduced mass floating nut system and method of assembling two parts using said system. Technical field

[0001] The present invention relates to a floating nut system of reduced mass and a method of assembling two parts using said system. State of the art

[0002] When a part is to be assembled with another part, there may be misalignments between the two parts due to assembly tolerances. The most common way to overcome this misalignment is the use of a floating nut, consisting of a captive metal nut in a metal cage. Before assembly, this metal cage can be installed by operations such as cold expansion in a hole in one of the parts or by riveting into one of the parts.

[0003] This type of floating nut therefore requires tedious operations to be installed. When the number of floating nuts is large, the installation time can be long and the operations tedious. For example, approximately four thousand floating nuts can be installed for a ventral fairing of an aircraft.

[0004] The set of floating nuts then has a very significant mass. Statement of the invention

[0005] The object of the present invention is to propose a floating nut system of reduced mass for an assembly between two parts to be assembled.

[0006] For this, it relates to a floating nut system intended to assemble a first part and a second part, the first part comprising a first opening intended for the passage of a screw, the first opening having a first axis of revolution.

[0007] According to the invention, the floating nut system comprises at least one elastomer cage device and one nut device, the cage device comprising: - a first hollow cylinder having a second axis of revolution and an external diameter substantially equal to a diameter of a second opening made in the second part, the first cylinder being intended to be introduced into the second opening through a first end of the first cylinder, - a first crown projecting around a second end of the first cylinder on the external surface of the first cylinder, the first crown having a diameter intended to be greater than the diameter of the second opening; the nut device comprising: - a second hollow cylinder having a third axis of revolution parallel to the second axis of revolution and an internal surface comprising a thread, the thread being intended to cooperate with the screw by screwing the screw, - a washer secured to the second cylinder, the washer going around the second cylinder, the washer having a diameter intended to be greater than the diameter of the second opening, the washer being embedded in the first crown, the washer being intended to press the first crown against the second part when the screw is screwed into the thread; the first cylinder being configured to deform when the screw is screwed in so that the first axis of revolution and the third axis of revolution are substantially coincident when a screw is screwed into the thread.

[0008] Thus, thanks to the elastomer cage device, the floating nut system has a reduced mass while compensating for misalignment between the two parts to be assembled.

[0009] Furthermore, the cage device comprises a second crown projecting around the first end of the first cylinder on an external surface of the first cylinder, the second crown having a diameter configured to be greater than the diameter of the second opening, the second crown being elastically deformable so that, on the one hand, it folds against the first cylinder to pass through the second opening when a user forces the cage device through the second opening parallel to the second axis of revolution, and, on the other hand, it unfolds after it has passed through the second opening, the second crown being intended to be clamped between the first part and the second part when the screw is screwed into the thread.

[0010] According to one embodiment, the second crown comprises a plurality of fins projecting around the first end of the first cylinder.

[0011] Advantageously, the external surface of the first cylinder has a plurality of longitudinal grooves parallel to each other, each of the grooves being arranged in line with each of the fins, each of the grooves being intended to house the fin in line with which a groove is arranged when said fin is folded so that the second crown can pass through the second opening when a user forces the passage of the cage device through the second opening parallel to the second axis of revolution.

[0012] Furthermore, the nut device comprises a conical portion integral with the second cylinder, the conical portion having a truncated cone shape having a small base connecting the conical portion to a first end of the second cylinder and a large base intended to face the first opening.

[0013] Further, the floating nut system includes a ring having a re axis revolution merged with the second axis of revolution, the ring being embedded in the first cylinder, the ring having a thickness substantially intended to be equal to a thickness of the second part capable of being assembled to the first part by the floating nut system, the ring being configured so as not to deform when the first cylinder deforms.

[0014] In addition, the first crown has a circular edge, the first crown having a cylindrical wall on the circular edge, the cylindrical wall having a free end intended to be pressed against the second part when the screw is screwed into the thread.

[0015] The invention also relates to a method of assembling a first part and a second part using a floating nut system as specified above.

[0016] According to the invention, the method comprises the following steps: - a step of introducing the first cylinder into the second opening through the first end of the first cylinder; - a step of introducing a screw into the first opening; - a first step of deformation by shearing of the first cylinder until the first axis of revolution of the first cylinder and the third axis of revolution of the second cylinder are substantially coincident; - a step of introducing the screw into the second cylinder; - a step of screwing the screw into the thread of the internal surface of the second cylinder; - a second stage of deformation by compression of the first cylinder until the washer presses the first crown against the second part.

[0017] In addition, the step of introducing the first cylinder comprises: - a sub-stage for folding the second crown by elastic deformation against the first cylinder passing through the second opening; - a sub-step of unfolding the second crown after the second crown has passed through the second opening.

[0018] Furthermore, the first deformation step comprises: - a sub-step of introducing the screw into the conical part; - a sub-step of deformation of the first cylinder as the screw enters the conical part until the screw enters the second cylinder. Brief description of the figures

[0019] The attached figures will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

[0020] [Fig.l] shows a perspective view of the floating nut system.

[0021] [Fig.2] shows a diametrical section of the floating nut system and two parts to assemble.

[0022] [Fig.3] schematically represents the assembly process using the floating nut system.

[0023] [Fig.4] represents a diametrical section of the floating nut system and the two parts to be assembled before the introduction of the first cylinder into the second opening.

[0024] [Fig.5] represents a diametrical section of the floating nut system and the two parts to be assembled at the start of the introduction of the first cylinder into the second opening.

[0025] [Fig.6] shows a diametrical section of the floating nut system and the two parts to be assembled during the introduction of the first cylinder into the second opening.

[0026] [Fig.7] shows a diametrical section of the floating nut system, the two parts to be assembled and a screw during the introduction of the screw into the first opening.

[0027] [Fig.8] shows a diametrical section of the floating nut system, the two parts to be assembled and the screw at the start of screwing the screw into the thread of the second cylinder.

[0028] [Fig.9] shows a diametrical section of the floating nut system, the two parts to be assembled and the screw when the screw is completely screwed into the thread of the second cylinder. Detailed description

[0029] [Fig.l] and [Fig.2] represent the floating nut system 1 intended to assemble a first part 2 and a second part 3.

[0030] In a non-limiting manner, the first part 2 and the second part 3 may each correspond to a metal plate that it is desired to assemble. The first part 2 and the second part 3 may also correspond to aircraft ventral fairings that it is desired to assemble.

[0031] The first part 2 has a first opening 4 intended for the passage of a screw 5. The first opening 4 has a first axis of revolution AL

[0032] The first opening 4 may have been made in advance by a tool before the placement of the first part 2 relative to the second part 3.

[0033] The floating nut system 1 comprises at least one elastomer cage device 6 and a nut device 7. The cage device 6 traps the nut device 7.

[0034] The cage device 6 comprises a first hollow cylinder 8. The first cylinder 8 has a second axis of revolution A2. The external diameter DI of the first cylinder 8 is substantially equal to a diameter of a second opening 9 made in the second part 3. As for the first opening 4, the second opening 9 may have been made in advance by a tool before the placement of the first part 2 relative to the second part 3.

[0035] The first cylinder 8 is intended to be introduced into the second opening 9 by a first end 10 of the first cylinder 8.

[0036] The cage device 6 also comprises a first crown 11. The first crown 11 projects around a second end 12 of the first cylinder 8 on the external surface 80 of the first cylinder 8. The first crown 11 has a diameter D2 intended to be greater than the diameter of the second opening 9.

[0037] The nut device 7 comprises a second hollow cylinder 13 having a third axis of revolution A3 parallel to the second axis of revolution A2. The internal surface 14 of the second cylinder 13 comprises a thread. The thread is intended to cooperate with the screw 5 by screwing the screw 5 into said thread.

[0038] The nut device 7 further comprises a washer 15 secured to the second cylinder 13. The washer 15 goes around the second cylinder 13, otherwise, the washer 15 projects around the second cylinder 13. The washer 15 has a diameter D3 intended to be greater than the diameter of the second opening 9. The washer 15 is embedded in the first crown 11. The washer 15 is intended to deform the first cylinder 8 by pressing the first crown 11 against the second part 3 when the screw 5 is screwed into the thread.

[0039] The first cylinder 8 is configured to deform when the screw 5 is screwed in so that the first axis of revolution A1 and the third axis of revolution A3 are substantially coincident when a screw 5 is screwed into the thread. In a non-limiting manner, the configuration allowing the first cylinder 8 to be deformed may depend on the material from which the cage device 6 is manufactured and the thickness of the wall of the first cylinder 8.

[0040] The nut device 7 may be made of a metallic material, such as stainless steel or aluminum.

[0041] Advantageously, the cage device 6 further comprises a second crown 16 projecting around the first end 10 of the first cylinder 8 on an external surface 80 of the first cylinder 8. The second crown 16 having a diameter D4 configured to be greater than the diameter of the second opening 9. The second crown 16 is configured to be elastically deformable so that, on the one hand, it folds against the first cylinder 8 to pass through the second opening 9 when a user forces the passage of the cage device 6 through the second opening 9 parallel to the second axis of revolution A2 ([Fig.5] and [Fig.6]), and, on the other hand, it unfolds after it has passed through of the second opening 9 ([Fig.7]).

[0042] The second crown 16 is intended to be clamped between the first part 2 and the second part 3 when the screw 5 is screwed into the thread.

[0043] The second crown 16 sandwiched between the first part 2 and the second part 3 makes it possible to hold the first cylinder 8 in the second opening 9 during an assembly process (described below) of the first part 2 and the second part 3. Thus, the first cylinder 8 does not escape from the second opening 9 during said assembly process.

[0044] According to one embodiment, the second crown 16 comprises a plurality of fins 17 projecting around the first end 10 of the first cylinder 8.

[0045] The external surface 80 of the first cylinder 8 may have a plurality of longitudinal grooves 18 parallel to each other. Each of the grooves 18 is arranged in line with each of the fins 17. Each of the grooves 18 is intended to house the fin 17 in line with which a groove 18 is arranged when said fin 17 is folded so that the second crown 16 can pass through the second opening 9 when a user forces the passage of the cage device 6 (or the floating nut system 1) through the second opening 9 parallel to the second axis of revolution A2. [Fig. 6] shows a moment of the introduction of the floating nut system 1 during which the fins are folded into the grooves 18 allowing the passage of the cage device 8 through the second opening 9.

[0046] Advantageously, the nut device 7 comprises a conical part 19 secured to the second cylinder 13. The conical part 19 has the shape of a truncated cone having a small base 21 and a large base 22. The small base 21 connects the conical part 19 to a first end 20 of the second cylinder 13. The large base 22 is intended to face the first opening 4 when the first cylinder 8 is introduced into the second opening 9. The conical part 19 makes it possible to guide the free end of the screw 5 towards the second cylinder 13 in order to screw the screw 5 into the thread of the second cylinder 13.

[0047] The floating nut system 1 may further comprise a ring 23 having an axis of revolution coinciding with the second axis of revolution A2 when the first cylinder 8 is not deformed. The ring 23 is embedded in the first cylinder 8. The ring 23 has a thickness D5 substantially intended to be equal to a thickness of the second part 3 capable of being assembled to the first part 2 by the floating nut system 1. The ring 23 is configured not to deform when the first cylinder 8 deforms. The ring makes it possible to maintain the cylindrical shape of the first cylinder 8 at the second opening 9.

[0048] The first crown 11 may have a circular edge 24. The first crown 11 may have a cylindrical wall 25 on the circular edge 24. The cylindrical wall The lindrique 11 has a free end 26 intended to be pressed against the second part 3 when the screw 5 is screwed into the thread.

[0049] The invention also relates to a method of assembling a first part 2 and a second part 3 using the floating nut system 1 ([Fig.3]).

[0050] The assembly method comprises the following steps: - a step E1 of introducing the first cylinder 8 into the second opening 9 via the first end 10 of the first cylinder 8 ([Fig.4], [Fig.5] and [Fig.6]); - a step E2 of introducing a screw 5 into the first opening 4 ([Fig.7]); - a first step E3 of deformation by shearing of the first cylinder 8 until the first axis of revolution A1 of the first cylinder 8 and the third axis of revolution A3 of the second cylinder 13 are substantially merged ([Fig.8]); - a step E4 of introducing the screw 5 into the second cylinder 13 ([Fig.8]); - a step E5 of screwing the screw 5 into the thread of the internal surface 14 of the second cylinder 13;

[0051] - a second step E6 of deformation by compression of the first cylinder 8 until the washer 15 presses the first crown 11 against the second part 3 ([Fig.9]).

[0052] Step E1 of introducing the first cylinder 8 may comprise: - a sub-stage El 1 for folding the second crown 16 by elastic deformation against the first cylinder 8 passing through the second opening 9 ([Fig.5] and [Fig.6]); - a sub-step E12 of unfolding the second crown 16 after the passage of the second crown 16 in the second opening 9 ([Fig.7]).

[0053] The first deformation step E3 may comprise: - a sub-step E31 of introducing the screw 5 into the conical part (19) ([Fig.7]); - a sub-step E32 of deformation of the first cylinder 8 as the screw 5 enters the conical part 19 until the screw 5 enters the second cylinder 13 ([Fig.8]).

[0054] Thus, the first cylinder 8 is likely to deform due to two mechanical stresses. The first mechanical stress corresponds to a shear stress. The deformation of the first cylinder 8 by the shear stress makes it possible to ensure that the first axis of revolution A1 of the first cylinder 8 and the third axis of revolution A3 of the second cylinder 13 are substantially coincident. The shear stress is exerted by the movement of the washer 15 driven by the screw 5. The screw 5 is guided towards the second cylinder 13 to be screwed there by the conical part 19 of the nut device 7. The second mechanical stress corresponds to a uniaxial compressive stress. The deformation formation of the first cylinder 8 by the uniaxial compressive stress occurs when the screw 5 is screwed into the second cylinder 13 until the screw 5 is screwed completely. The uniaxial compressive stress has a direction parallel to the third axis of revolution A3. The uniaxial compressive stress is therefore exerted by the washer 15. When the screw 5 is screwed into the second cylinder 13, the screw 5 pulls the washer 15 towards the second part 3. The washer 15 thus exerts a compressive stress on the first cylinder 8.

[0055] The floating nut system 1 provides many advantages.

[0056] - it has a reduced mass compared to that of the floating nuts of the art prior.

[0057] - it allows to reduce the assembly time in the factory.

[0058] - it can be used in cases of small or large buoyancy, that is to say it can be used in case of small or large misalignment between the two parts to be assembled.

[0059] - it can be used in a wide range of configurations, for example in the ventral fairing of an aircraft, an aircraft cabin, etc.

[0060] - it has great repairability by being easy and quick to replace in the event of need.

[0061] - it presents an isostatism allowing a filtration of the vibrations exerted by the assembled parts.

[0062] - it helps to avoid problems of galvanic corrosion.

Claims

1. Claims Floating nut system intended to assemble a first part (2) and a second part (3), the first part (2) comprising a first opening (4) intended for the passage of a screw (5), the first opening (4) having a first axis of revolution (Al), characterized in that it comprises at least one cage device (6) made of elastomer and a nut device (7), the cage device (6) comprising: - a first hollow cylinder (8) having a second axis of revolution (A2) and an external diameter (Dl) substantially equal to a diameter of a second opening (9) made in the second part (3), the first cylinder (8) being intended to be introduced into the second opening (9) by a first end (10) of the first cylinder (8), - a first crown (11) projecting around a second end (12) of the first cylinder (8) on the external surface (80) of the first cylinder (8), the first crown (11) having a diameter (D2) intended to be greater than the diameter of the second opening (9); the nut device (7) comprising: - a second hollow cylinder (13) having a third axis of revolution (A3) parallel to the second axis of revolution (A2) and an internal surface (14) comprising a thread, the thread being intended to cooperate with the screw (5) by screwing the screw (5), - a washer (15) secured to the second cylinder (13), the washer (15) going around the second cylinder (13), the washer (15) having a diameter (D3) intended to be greater than the diameter of the second opening (9), the washer (15) being embedded in the first crown (11), the washer (15) being intended to press the first crown (11) against the second part (3) when the screw (5) is screwed into the thread; the first cylinder (8) being configured to deform during screwing of the screw (5) so that the first axis of revolution (Al) and the third axis of revolution (A3) are substantially coincident when a screw (5) is screwed into the thread.

2. System according to claim 1, characterized in that the cage device (6) further comprises a second crown (16) projecting around the first end (10) of the first cylinder (8) on an external surface (80) of the first cylinder (8), the second crown (16) having a diameter (D4) configured to be greater than the diameter of the second opening (9), the second crown (16) being elastically deformable so that, on the one hand, it folds against the first cylinder (8) to pass through the second opening (9) when a user forces the passage of the cage device (6) through the second opening (9) parallel to the second axis of revolution (A2), and, on the other hand, it unfolds after it has passed through the second opening (9), the second crown (16) being intended to be clamped between the first part (2) and the second part (3) when the screw (5) is screwed into the thread.

3. System according to claim 2, characterized in that the second crown (16) comprises a plurality of fins (17) projecting around the first end (10) of the first cylinder (8).

4. System according to claim 3, characterized in that the external surface (80) of the first cylinder (8) has a plurality of longitudinal grooves (18) parallel to each other, each of the grooves (18) being arranged in line with each of the fins (17), each of the grooves (18) being intended to house the fin (17) in line with which a groove (18) is arranged when said fin (17) is folded so that the second crown (16) can pass through the second opening (9) when a user forces the passage of the cage device (6) through the second opening (9) parallel to the second axis of revolution (A2).

5. System according to one of claims 1 to 4, characterized in that the nut device (7) comprises a conical part (19) integral with the second cylinder (13), the conical part (19) having a truncated cone shape having a small base (21) connecting the conical part (19) to a first end (20) of the second cylinder (13) and a large base (22) intended to face the first opening (4).

6. System according to one of claims 1 to 5, characterized in that it further comprises a ring (23) having an axis of revolution coincident with the second axis of revolution (A2), the ring (23) being embedded in the first cylinder (8), the ring (23) having a thickness (D5) substantially intended to be equal to a thickness of the second part (3) capable of being assembled to the first part (2) by the floating nut system (1), the ring (23) being configured not to deform when the first cylinder (8) deforms.

7. System according to one of claims 1 to 6, characterized in that the first crown (11) has a circular edge (24), the first crown (11) comprising a cylindrical wall (25) on the circular edge (24), the cylindrical wall (11) having a free end (26) intended to be pressed against the second part (3) when the screw (5) is screwed into the thread.

8. Method for assembling a first part (2) and a second part (3) using a floating nut system (1) according to one of claims 1 to 7, characterized in that it comprises the following steps: - a step (El) of introducing the first cylinder (8) into the second opening (9) via the first end (10) of the first cylinder (8); - a step (E2) of introducing a screw (5) into the first opening (4); - a first step (E3) of deforming by shearing the first cylinder (8) until the first axis of revolution (Al) of the first cylinder (8) and the third axis of revolution (A3) of the second cylinder (13) are substantially coincident; - a step (E4) of introducing the screw (5) into the second cylinder (13); - a step (E5) of screwing the screw (5) into the thread of the internal surface (14) of the second cylinder (13);- a second step (E6) of deformation by compression of the first cylinder (8) until the washer (15) presses it; first crown (11) against the second piece (3).

9. A method according to claim 8, characterized in that the step (El) of introducing the first cylinder (8) comprises: - a sub-stage (El 1) for folding the second crown (16) by elastic deformation against the first cylinder (8) passing through the second opening (9); - a sub-step (El2) of unfolding the second crown (16) after the passage of the second crown (16) in the second opening (9).

10. Method according to one of claims 8 and 9, characterized in that the first deformation step (E3) comprises: - a sub-step (E31) of introducing the screw (5) into the conical part (19); - a sub-step (E32) of deforming the first cylinder (8) as the screw (5) enters the conical part (19) until the screw (5) enters the second cylinder (13).

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