Floating nut system with reduced mass and method for joining two parts with this system

Description

technical field

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

[0002] When one part is to be assembled with another, misalignments between the two parts can occur due to assembly tolerances. The most common way to compensate for this misalignment is to use a floating nut, consisting of a metal nut held captive 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 it into one of the parts.

[0003] This type of floating nut therefore requires tedious operations to install. When the number of floating nuts is large, the installation time can be lengthy and the operations tedious. For example, approximately four thousand floating nuts can be installed for the ventral fairing of an aircraft. The entire assembly of floating nuts then represents a very significant mass. A prior art floating nut system is disclosed in document EP3724520 B1. Description of the invention

[0004] The present invention aims to provide a low-mass floating nut system for assembly between two parts to be assembled, with the technical characteristics of claim 1.

[0005] For this purpose, it concerns a floating nut system intended to assemble a first part and a second part, the first part having a first opening intended for the passage of a screw, the first opening having a first axis of revolution.

[0006] 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 piece, the first cylinder being intended to be inserted into the second opening by a first end of the first cylinder, a first ring projecting around a second end of the first cylinder on the external surface of the first cylinder, the first ring 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 having a thread, the thread being intended to cooperate with the screw by tightening the screw, a washer integral with 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 ring, the washer being intended to press the first ring against the second piece when the screw is tightened into the thread; the first cylinder being configured to deform when the screw is tightened so that the first axis of revolution and the third axis of revolution are substantially coincident when a screw is tightened into the thread.

[0007] 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.

[0008] In addition, the cage device includes a second ring projecting around the first end of the first cylinder on an external surface of the first cylinder, the second ring having a diameter configured to be greater than the diameter of the second opening, the second ring being elastically deformable so that, on the one hand, it bends against the first cylinder to 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, and, on the other hand, it unfolds after it has passed through the second opening, the second ring being intended to be clamped between the first piece and the second piece when the screw is screwed into the thread.

[0009] According to one embodiment, the second crown comprises a plurality of fins projecting around the first end of the first cylinder.

[0010] Advantageously, the external surface of the first cylinder has a plurality of parallel longitudinal grooves, each of the grooves being arranged opposite each of the fins, each of the grooves being intended to house the fin opposite which a groove is arranged when said fin is bent so that the second ring 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.

[0011] Furthermore, the nut device includes a conical part attached to the second cylinder, the conical part having a truncated cone shape with a small base connecting the conical part to a first end of the second cylinder and a large base intended to face the first opening.

[0012] In addition, the floating nut system includes a ring having an axis of revolution coinciding 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 piece capable of being assembled to the first piece by the floating nut system, the ring being configured so as not to deform when the first cylinder deforms.

[0013] In addition, the first ring has a circular edge, the first ring having a cylindrical wall on the circular edge, the cylindrical wall having a free end intended to be pressed against the second piece when the screw is screwed into the thread.

[0014] The invention also relates to a method of assembling a first part and a second part using a floating nut system as specified above, according to claim 8.

[0015] According to the invention, the process comprises the following steps: a step of introducing the first cylinder into the second opening by the first end of the first cylinder; a step of introducing a screw into the first opening; a first step of shearing 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 step of compressing the first cylinder until the washer presses the first ring against the second piece.

[0016] Furthermore, the first cylinder introduction step includes: a substage of folding the second ring by elastic deformation against the first cylinder by passing through the second opening; a substage of unfolding the second ring after the second ring has passed through the second opening.

[0017] Furthermore, the first deformation stage includes: a sub-step of introducing the screw into the conical part; a sub-step of deforming the first cylinder as the screw enters the conical part until the screw enters the second cylinder. Brief description of the figures

[0018] The accompanying figures will clearly illustrate how the invention can be implemented. In these figures, identical reference numerals designate similar elements. There figure 1 represents a perspective view of the floating nut system. figure 2represents a diametrical cross-section of the floating nut system and two parts to be assembled. figure 3 This schematically represents the assembly process using the floating nut system. figure 4 represents a diametrical cross-section of the floating nut system and the two parts to be assembled before the first cylinder is inserted into the second opening. figure 5 This represents a diametrical cross-section of the floating nut system and the two parts to be assembled at the beginning of the insertion of the first cylinder into the second opening. figure 6 represents a diametrical cross-section of the floating nut system and the two parts to be assembled during the insertion of the first cylinder into the second opening. figure 7 represents a diametrical cross-section of the floating nut system, the two parts to be assembled, and a screw during the insertion of the screw into the first opening. figure 8This represents a diametrical cross-section of the floating nut system, the two parts to be assembled, and the screw at the beginning of the screw's insertion into the thread of the second cylinder. figure 9 represents a diametrical cross-section of the floating nut system, the two parts to be assembled, and the screw when the screw is fully screwed into the thread of the second cylinder. Detailed description

[0019] There figure 1 and the figure 2 represent the floating nut system 1 intended to assemble a first part 2 and a second part 3.

[0020] By way of example, the first part 2 and the second part 3 could each correspond to a metal plate to be assembled. The first part 2 and the second part 3 could also correspond to aircraft ventral fairings to be assembled.

[0021] The first part 2 has a first opening 4 for the passage of a screw 5. The first opening 4 has a first axis of revolution A1.

[0022] The first opening 4 may have been made in advance by a tool before the placement of the first piece 2 relative to the second piece 3.

[0023] The floating nut system 1 comprises at least one elastomer cage device 6 and a nut device 7. The cage device 6 encloses the nut device 7.

[0024] The cage device 6 comprises a first hollow cylinder 8. The first cylinder 8 has a second axis of revolution A2. The external diameter D1 of the first cylinder 8 is substantially equal to the diameter of a second opening 9 made in the second part 3. As with the first opening 4, the second opening 9 may have been made beforehand by a tool prior to the positioning of the first part 2 relative to the second part 3.

[0025] The first cylinder 8 is intended to be inserted into the second opening 9 by a first end 10 of the first cylinder 8.

[0026] The cage device 6 also includes a first ring 11. The first ring 11 projects around a second end 12 of the first cylinder 8 on the external surface 80 of the first cylinder 8. The first ring 11 has a diameter D2 intended to be larger than the diameter of the second opening 9. The nut device 7 includes 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 has a thread. The thread is intended to cooperate with the screw 5 by screwing the screw 5 into said thread.

[0027] The nut assembly 7 further includes a washer 15 attached to the second cylinder 13. The washer 15 encircles the second cylinder 13; otherwise, the washer 15 protrudes around the second cylinder 13. The washer 15 has a diameter D3 intended to be larger than the diameter of the second opening 9. The washer 15 is embedded in the first ring 11. In addition to being embedded, further fastening means may be provided, such as overmolding, bonding, or any other equivalent means of attaching the washer to the ring. The washer 15 is intended to deform the first cylinder 8 by pressing the first ring 11 against the second part 3 when the screw 5 is screwed into the thread. 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.Without limitation, the configuration for deforming the first cylinder 8 may depend on the material in which the cage device 6 is made and the wall thickness of the first cylinder 8.

[0028] The nut device 7 can be made of metallic material, such as stainless steel or aluminum.

[0029] Advantageously, the cage device 6 further comprises a second ring 16 projecting around the first end 10 of the first cylinder 8 on an external surface 80 of the first cylinder 8. The second ring 16 has a diameter D4 configured to be greater than the diameter of the second opening 9. The second ring 16 is configured to be elastically deformable so that, on the one hand, it bends 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 ( Figure 5 and Figure 6 ), and, on the other hand, that it unfolds after it has passed through the second opening 9 ( figure 7 ).

[0030] 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.

[0031] The second ring 16, sandwiched between the first part 2 and the second part 3, allows the first cylinder 8 to be held 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.

[0032] According to one embodiment, the second ring 16 comprises a plurality of fins 17 projecting around the first end 10 of the first cylinder 8. The external surface 80 of the first cylinder 8 may have a plurality of parallel longitudinal grooves 18. Each of the grooves 18 is located opposite each of the fins 17. Each of the grooves 18 is designed to house the fin 17, opposite which a groove 18 is located when said fin 17 is bent so that the second ring 16 can pass through the second opening 9 when a user forces the cage device 6 (or the floating nut system 1) through the second opening 9 parallel to the second axis of revolution A2. The figure 6This shows a moment during the introduction of the floating nut system 1, during which the fins are bent into the grooves 18, allowing the cage device 6 to pass through the second opening 9. Advantageously, the nut device 7 includes a conical portion 19 integral with the second cylinder 13. The conical portion 19 has a truncated cone shape with a small base 21 and a large base 22. The small base 21 connects the conical portion 19 to a first end 20 of the second cylinder 13. The large base 22 is designed to face the first opening 4 when the first cylinder 8 is inserted into the second opening 9. The conical portion 19 guides the free end of the screw 5 towards the second cylinder 13 so that the screw 5 can be screwed into the threads of the second cylinder 13.

[0033] The floating nut system 1 may further include 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 that can be assembled to the first part 2 by the floating nut system 1. The ring 23 is configured so as not to deform when the first cylinder 8 deforms. The ring allows the cylindrical shape of the first cylinder 8 to be maintained at the second opening 9.

[0034] The first ring 11 may have a circular edge 24. The first ring 11 may have a cylindrical wall 25 on the circular edge 24. The cylindrical wall 11 has a free end 26 intended to be pressed against the second piece 3 when the screw 5 is screwed into the thread.

[0035] The invention also relates to a method of assembling a first part 2 and a second part 3 using the floating nut system 1 ( figure 3 ).

[0036] The assembly process includes the following steps: a step E1 of introducing the first cylinder 8 into the second opening 9 by the first end 10 of the first cylinder 8 ( figure 4, figure 5 and figure 6 ) ; a step E2 of introducing a screw 5 into the first opening 4 ( figure 7 ); a first shear deformation stage E3 of the first cylinder 8 until the first axis of revolution A1 of the opening 4 and the third axis of revolution A3 of the second cylinder 13 are substantially coincident ( figure 8 ) ; a step E4 of introducing screw 5 into the second cylinder 13 ( figure 8) ; 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 compressive deformation of the first cylinder 8 until the washer 15 presses the first ring 11 against the second piece 3 ( figure 9 ).

[0037] Step E1, the introduction of the first cylinder 8, may include: a substage E11 of folding of the second ring 16 by elastic deformation against the first cylinder 8 passing through the second opening 9 ( Figure 5 and Figure 6 ) ; a substep E12 of unfolding the second ring 16 after the passage of the second ring 16 through the second opening 9 ( figure 7 ).

[0038] The first deformation stage E3 may include: a substep E31 of introducing the screw 5 into the conical part (19) ( figure 7) ; a substep 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 ( figure 8 ).

[0039] Thus, the first cylinder 8 is susceptible to deformation due to two mechanical stresses. The first mechanical stress is a shear stress. The deformation of the first cylinder 8 by the shear stress causes the first axis of revolution A1 of the opening 4 and the third axis of revolution A3 of the second cylinder 13 to essentially coincide. The shear stress is exerted by the displacement of the washer 15 driven by the screw 5. The screw 5 is guided towards the second cylinder 13 to be screwed into it by the conical part 19 of the nut device 7. The second mechanical stress is a uniaxial compressive stress. The deformation 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 fully tightened.The uniaxial compressive stress is 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.

[0040] The floating nut system 1 offers many advantages. It has a reduced mass compared to prior art floating nuts. It reduces factory assembly time. It can be used in cases of small or large buoyancy, meaning it can be used in cases of small or large misalignment between the two parts to be joined. It can be used in a wide range of configurations, for example in the ventral fairing of an aircraft, an aircraft cabin, etc. It offers high repairability, being easy and quick to replace when necessary. Its isostatic properties allow for the filtering of vibrations exerted by the assembled parts. It helps prevent galvanic corrosion problems.

Claims

1. Floating nut system intended for assembling a first component part (2) and a second component part (3), the first component 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 (A1), wherein the system 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 outside diameter (D1) substantially equal to a diameter of a second opening (9) made in the second component part (3), the first cylinder (8) being intended to be introduced into the second opening (9) via a first end (10) of the first cylinder (8), - a first ring (11) projecting around a second end (12) of the first cylinder (8) on the external surface (80) of the first cylinder (8), the first ring (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) through the screwing-in of the screw (5), - a washer (15) secured to the second cylinder (13), the washer (15) encircling 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 set in the first ring (11), the washer (15) being intended to press the first ring (11) against the second component part (3) when the screw (5) is screwed into the thread; the first cylinder (8) being configured to deform during the screwing-in of the screw (5) 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.

2. System according to Claim 1, characterized in that the cage device (6) further comprises a second ring (16) projecting around the first end (10) of the first cylinder (8) on an external surface (80) of the first cylinder (8), the second ring (16) having a diameter (D4) configured to be greater than the diameter of the second opening (9), the second ring (16) being elastically deformable so that, on the one hand, it can fold against the first cylinder (8) in order to pass through the second opening (9) when a user forces the cage device (6) to pass 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 ring (16) being intended to be clamped between the first component part (2) and the second component part (3) when the screw (5) is screwed into the thread.

3. System according to Claim 2, characterized in that the second ring (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 mutually parallel longitudinal grooves (18), 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 ring (16) can pass through the second opening (9) when a user forces the cage device (6) to pass 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 portion (19) secured to the second cylinder (13), the conical portion (19) having a truncated cone shape having a small base (21) connecting the conical portion (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 hoop (23) having an axis of revolution coincident with the second axis of revolution (A2), the hoop (23) being set in the first cylinder (8), the hoop (23) having a thickness (D5) substantially intended to be equal to a thickness of the second component part (3) capable of being assembled with the first component part (2) by the floating nut system (1), the hoop (23) being configured so as not to deform when the first cylinder (8) deforms.

7. System according to one of Claims 1 to 6, characterized in that the first ring (11) has a circular edge (24), the first ring (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 component part (3) when the screw (5) is screwed into the thread.

8. Method for assembling a first component part (2) and a second component part (3) using a floating nut system (1) according to one of Claims 1 to 7, wherein the 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); - a step (E2) of introducing a screw (5) into the first opening (4); - a first deformation step (E3) of deforming the first cylinder (8) by shearing until the first axis of revolution (A1) 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 deformation step (E6) of deforming the first cylinder (8) by compression until the washer (15) presses the first ring (11) against the second component part (3).

9. Method according to Claim 8, characterized in that the step (E1) of introducing the first cylinder (8) comprises: - a sub-step (E11) of folding the second ring (16) by elastic deformation against the first cylinder (8) by passing it through the second opening (9); - a sub-step (E12) of unfolding the second ring (16) after the second ring (16) has passed through the second opening (9).

10. Method according to either 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 portion (19); - a sub-step (E32) of deforming the first cylinder (8) as the screw (5) gradually enters the conical portion (19) until the screw (5) enters the second cylinder (13).