Blind fastening device and method for mounting a blind fastening device

Abstract

The present invention relates to a blind fastening device and a method for installing a blind fastening device. The blind fastening device for fastening a component includes an actuation rod comprising a deformed bushing and a sleeve comprising a deformed bushing and a deformable portion configured to deform radially when the deformed bushings are mated. The actuation rod includes a first drive nut followed by a first breakage groove configured to break when a tightening torque applied to the first drive nut exceeds a first predetermined torque, and a second drive nut followed by a second breakage groove configured to break when a retightening torque applied to the second drive nut exceeds a second predetermined torque greater than the first predetermined torque. The blind fastening device can be retightened after its installation.

Description

Technical Field

[0001] This application relates to blind fastening devices designed to allow for retightening of the fastening device after installation, and also to methods for installing this type of blind fastening device. Background Technology

[0002] Blind fastening devices are currently used, particularly in the aerospace industry, to assemble components when the operator responsible for assembling them only has access to the components from one side. These blind fastening devices will be used more widely in the future, as they are one of the key components for automating assembly lines.

[0003] Typically, joint seals are applied between components to be assembled, so that the components are sealed relative to fluids (e.g., impermeability to water and air used for pressurizing aircraft cabins) to prevent potential leaks, such as fuel leaks, and to prevent corrosion of one or more of the components that make up the assembly when the components are made of different materials (e.g., when one component is made of carbon fiber reinforced polymer (CFPR)).

[0004] The joint seal is typically applied prior to the final assembly step, thereby enabling the first element to be assembled to the second element.

[0005] After the joint seal is applied, during the creep and drying of the joint seal, it is necessary to maintain a predetermined pressure on the assembly in order to ensure a complete seal of the structure to be assembled.

[0006] To ensure proper pressing of the joint seal, it is necessary to use temporary fastening devices. This method includes: installing temporary fastening devices to assemble the components; applying necessary pressure to the assembly to ensure pre-tightening and uniform seal thickness at the joint between the first and second assembled components; and replacing the temporary fastening devices with final fastening devices, wherein the final fastening devices are properly tightened to ensure proper contact and sufficient tightening force between the components to be assembled. However, this method is costly in terms of time and materials because it requires the installation and removal of numerous temporary fastening devices.

[0007] To eliminate the need for temporary fasteners, it is necessary to use a final fastener that can be retightened after the seal has been pressed and dried. The first tightening of the final fastener ensures pressure on the joint seal, and the second tightening (i.e., retightening) ensures proper preloading of the final fastener after the seal has been pressed, and ensures tight contact between the components to be assembled. However, this type of blind fastener does not currently exist because existing blind fasteners are not designed to be retightened.

[0008] Therefore, a blind fastening device is needed to assemble components together to form an assembly that can be fastened once and then retightened. Summary of the Invention

[0009] The purpose of this invention is to provide a solution that allows blind fasteners to be retightened after installation.

[0010] For this purpose, the subject of the present invention is a blind fastening device for fastening an assembly consisting of a first element and a second element, wherein a joint seal is positioned between the first element and the second element, and each of the first element and the second element includes an orifice having a first inner diameter, the blind fastening device comprising:

[0011] - An actuator rod having a first end and a second end, and the actuator rod comprising: a first drive nut located at the first end of the actuator rod, a first fracture groove located between the first drive nut and the second end of the actuator rod, a threaded portion located between the first fracture groove and the second end of the actuator rod, and a deformable bushing located at the second end of the actuator rod.

[0012] - A sleeve capable of being inserted into the orifices of the first element and the second element, and having a first outer diameter substantially equal to a first inner diameter, the sleeve being threadedly connected to an actuator rod, and having a first end and a second end, and the sleeve comprising: a tapped portion located between the first end and the second end of the sleeve, a deformable bushing located at the second end of the sleeve, and a deformable portion located between the first end and the second end of the sleeve, the deformable portion being configured to deform radially when the deformable bushing of the actuator rod engages with the deformable bushing of the sleeve, until the sleeve has a second outer diameter larger than the first outer diameter.

[0013] The first fracture groove is configured to fracture when the tightening torque applied to the first drive nut, causing the threaded portion of the actuator rod to engage with the tapped portion of the sleeve, exceeds a first predetermined torque.

[0014] According to the invention, the actuating rod includes a second drive nut, which is followed by a second fracture groove located between a first fracture groove and a threaded portion, the second fracture groove being configured to fracture when the retightening torque applied to the second drive nut exceeds a second predetermined torque greater than the first predetermined torque.

[0015] Advantageously, the presence of the second drive nut with the second fracture groove allows for the introduction of a re-tightening function of the blind fastener after pressing the joint seal between the first and second elements of the assembly, and more specifically, a re-tightening function of the actuator rod in the sleeve. Furthermore, since the second fracture groove is calibrated for a predetermined tightening torque, proper re-tightening of the blind fastener is guaranteed, and thus any under-tightening or over-tightening of the blind fastener is avoided.

[0016] According to another feature, the deformable bushing of the actuator rod is threaded, and the deformable bushing of the sleeve is tapped.

[0017] According to another feature, the deformable bushing of the actuator rod is in the form of a radial protrusion, and the deformable bushing of the sleeve is in the form of a radial expansion.

[0018] According to another feature, the deformable bushing of the actuator rod is in the form of a radial protrusion, and the deformable bushing of the sleeve is in the form of a support surface, against which the deformable bushing of the actuator rod is supported.

[0019] The subject of this invention also relates to a method for installing a blind fastening device according to the invention, the blind fastening device being used to fasten an assembly consisting of a first element and a second element, the method comprising:

[0020] - The step of inserting the blind fastening device into the orifice of the first element and the orifice of the second element;

[0021] - The step of engaging the deformable bushing of the actuator rod with the deformable bushing of the sleeve to radially deform the deformable portion of the sleeve until the sleeve has a second outer diameter larger than the first outer diameter, wherein the engagement of the deformable bushing of the actuator rod with the deformable bushing of the sleeve allows the threaded portion of the actuator rod to be arranged facing the tapped portion of the sleeve.

[0022] - The step of screwing the threaded part of the actuator rod into the tapped part of the sleeve by means of the first drive nut until the first fracture groove breaks.

[0023] According to the present invention, the method further includes:

[0024] - The step of tightening the threaded part of the actuator rod in the tapped part of the sleeve by means of the second drive nut until the second fracture groove breaks.

[0025] Advantageously, the installation of this type of fastening device makes it possible to avoid the use of temporary blind fastening devices and thus allows for the direct use of final blind fastening devices, which are then tightened after installation and pressing of the joint seal arranged between the first and second elements of the assembly.

[0026] According to another feature, the deformable bushing of the actuator rod is threaded, and the deformable bushing of the sleeve is tapped. The step of engaging the deformable bushing of the actuator rod with the deformable bushing of the sleeve includes the following sub-steps: screwing the deformable bushing of the actuator rod into the deformable bushing of the sleeve, such that the thread of the deformable bushing of the actuator rod engages with the tap of the deformable bushing of the sleeve.

[0027] According to another feature, the deformable bushing of the actuator rod is in the form of a radial protrusion, and the deformable bushing of the sleeve is in the form of a radial expansion portion. The step of engaging the deformable bushing of the actuator rod with the deformable bushing of the sleeve includes the following sub-step: pulling the deformable bushing of the actuator rod within the deformable bushing of the sleeve, such that the radial protrusion of the deformable bushing of the actuator rod engages with the radial expansion portion of the deformable bushing of the sleeve.

[0028] According to another feature, the deformable bushing of the actuator rod is in the form of a radial protrusion, and the deformable bushing of the sleeve is in the form of a support surface. The step of engaging the deformable bushing of the actuator rod with the deformable bushing of the sleeve includes the following sub-steps: pulling the deformable bushing of the actuator rod in the deformable bushing of the sleeve so that the radial protrusion of the deformable bushing of the actuator rod engages with the support surface of the deformable bushing of the sleeve.

[0029] The subject matter of the invention also includes an assembly comprising a first element and a second element comprising a blind fastening device according to the invention, the blind fastening device being designed to fasten the first element to the second element.

[0030] The subject of this invention also lies in an aircraft comprising at least one component according to the invention. Attached Figure Description

[0031] Other features and advantages will become apparent from the following description of the invention, which is provided by way of example only, with reference to the accompanying drawings:

[0032] Figure 1 This is a cross-sectional view of the unassembled blind fastening device and the first and second components to be assembled, illustrating the steps of a first embodiment of the invention;

[0033] Figure 2 It is a cross-sectional view of the blind fastening device being assembled and the first and second components to be assembled, illustrating another step of the first embodiment of the invention;

[0034] Figure 3 This is a cross-sectional view of the blind fastening device and the assembly consisting of the first element and the second element, illustrating another step of the first embodiment of the invention;

[0035] Figure 4 It is a cross-sectional view of a blind fastening device fastened in an assembly consisting of a first element and a second element, illustrating another step of the first embodiment of the invention;

[0036] Figure 5 This is a cross-sectional view of a blind fastening device being re-tightened in an assembly consisting of a first element and a second element, illustrating another step of the first embodiment of the invention.

[0037] Figure 6 This is a flowchart of a method for installing a blind fastening device for fastening an assembly consisting of a first element and a second element. The flowchart illustrates an embodiment of the present invention.

[0038] Figure 7 This is a cross-sectional view of the unassembled blind fastening device and the first and second components to be assembled, illustrating the steps of a second embodiment of the invention;

[0039] Figure 8 It is a cross-sectional view of the blind fastening device being assembled and the first and second components to be assembled, illustrating another step of the second embodiment of the invention;

[0040] Figure 9 This is a cross-sectional view of the blind fastening device and the assembly consisting of the first element and the second element, illustrating another step of the second embodiment of the invention;

[0041] Figure 10 This is a cross-sectional view of a blind fastening device being re-tightened in an assembly consisting of a first element and a second element, illustrating another step of the second embodiment of the invention.

[0042] Figure 11 This is a cross-sectional view of the unassembled blind fastening device and the first and second components to be assembled, illustrating the steps of a third embodiment of the invention;

[0043] Figure 12 It is a cross-sectional view of the blind fastening device being assembled and the first and second components to be assembled, illustrating another step of the third embodiment of the invention;

[0044] Figure 13 This is a cross-sectional view of the blind fastening device and the assembly composed of the first and second elements, illustrating another step of the third embodiment of the invention; and

[0045] Figure 14 This is a perspective view of an aircraft comprising a first element and a second element, illustrating an embodiment of the present invention. Detailed Implementation

[0046] Figures 1 to 5 This describes the installation of a first type of blind fastening device for securing aircraft components together. The first type of blind fastening device is a device used for blind fastening by tightening, and is referred to as a "tightening" blind fastening device.

[0047] like Figures 1 to 5 As illustrated, the blind fastening device 10 is used to fasten two elements 12, 14 to each other. In this case, the blind fastening device 10 is used to assemble the first element 12 and the second element 14, with the first element 12 located on the side of the assembly accessible to the operator, while the second element 14 is located on the inaccessible side of the assembly when the elements 12, 14 are fastened to each other.

[0048] Therefore, the first element 12 includes: a first surface 12a disposed on the accessible side of the assembly; and a second surface 12b disposed facing the second element 14. The second element includes: a first surface 14a disposed on the inaccessible side of the assembly; and a second surface 14b disposed facing the first element 12. A joint seal 16 is present between the first element 12 and the second element 14, and particularly between the two surfaces 12b and 14b of elements 12 and 14.

[0049] Each element 12, 14 includes through holes 12c, 14c, and a fastening device is designed to be inserted into the through holes 12c, 14c. For example... Figure 1 As indicated, these orifices 12c and 14c are coaxial along the longitudinal axis A. In this case, orifices 12c and 14c have a generally cylindrical shape with a circular base. Orifice 12c has a widened portion 12d at the first surface 12a of element 12, and the blind fastening device 10 is supported against the widened portion 12d.

[0050] The blind fastening device 10 includes: an actuating rod 18, which is a tightening rod in this case; and a sleeve 20 that receives the actuating rod 18 and is designed to be placed in the orifices 12c, 14c of the elements 12, 14 to be fastened to each other.

[0051] The actuating rod 18 includes a body extending longitudinally along a longitudinal axis A and having a first end 18a and a second end 18b. The first end 18a is disposed on the accessible side of the assembly, and the second end 18b is opposite to the first end 18a and disposed on the inaccessible side of the assembly when the actuating rod 18 is inserted into a sleeve 20, the sleeve 20 itself being placed in orifices 12c, 14c of the components 12, 14 to be assembled. The actuating rod 18 includes a threaded portion 18c located between its first end 18a and second end 18b, and a deformable bushing 18d located at the second end 18b of the actuating rod 18. In this case, the deformable bushing 18d is threaded. The actuating rod also includes a first drive nut 18e located at its first end 18a, the first drive nut 18e being separated from the body of the actuating rod 18 by a first fracture groove 18f. Therefore, the first fracture groove 18f is spaced apart from the first end 18a of the actuating rod 18, and allows for the definition of a first portion P18 of the actuating rod 18, which also includes a first drive nut 18e located at the first end 18a. The actuating rod 18 also includes a second drive nut 18g located between the first fracture groove 18f and the body of the actuating rod 18, the second drive nut 18g being spaced apart from the second end 18b of the actuating rod 18. The second drive nut 18g is separated from the body of the actuating rod 18 by a second fracture groove 18h. Therefore, the second drive nut 18g is arranged between the first fracture groove 18f and the second fracture groove 18h. The second portion D18 of the actuating rod 18 is thus defined and includes the second drive nut 18g and the second fracture groove 18h. Preferably, the second drive nut 18g is identical to the first drive nut 18e, allowing the operator to use the same tightening tool for both the first drive nut 18e and the second drive nut 18g. It will be understood that the first drive nut 18e and the second drive nut 18g may be different. The actuating rod 18 includes a cylindrical flange 18i disposed between the second fracture groove 18h and the body of the actuating rod 18, spaced apart from the second end 18b of the actuating rod 18. The flange 18i forms a radial protrusion (i.e., a protrusion in a radial direction relative to the longitudinal axis A) from the body of the actuating rod 18. The shape of the flange 18i is substantially complementary to the shape of the widened portion 12d of the aperture 12c of the element 12. Therefore, a third portion T18 of the actuating rod 18 is defined between the flange 18i and the second end 18b of the actuating rod 18. Therefore, between the first end 18a and the second end 18b of the actuator 18, the actuator 18 includes a first drive nut 18e, then a first fracture groove 18f, a second drive nut 18g, then a second fracture groove 18h, a flange 18i, a threaded portion 18c, and then a deformable bushing 18d. The first drive nut 18e, the first fracture groove 18f, the second drive nut 18g, the second fracture groove 18h, and the flange 18i are arranged continuously to each other.Apart from the flange 18i and the first fracture groove 18f and the second fracture groove 18h, the actuating rod 18 has a substantially constant diameter equal to the inner diameter of the sleeve 20. The actuating rod 18 is fitted into the sleeve 20 in a manner with very small clearance, i.e., with sufficient clearance, to allow the actuating rod 18 to be fastened into the sleeve 20.

[0052] Sleeve 20 includes a hollow cylindrical body extending longitudinally along a longitudinal axis A and defining a through orifice 20h. Sleeve 20 has: a first end 20a disposed on the accessible side of the assembly; and a second end 20b opposite to the first end 20a and disposed on the inaccessible side of the assembly when sleeve 20 is placed in the orifices 12c, 14c of the components 12, 14 to be assembled. Sleeve 20 includes a substantially annular flange 20c at its first end 20a. The external shape of flange 20c is substantially complementary to the shape of the widened portion 12d of the orifice 12c of component 12, and the internal shape of flange 20c is substantially complementary to the shape of the flange 18i of actuator rod 18. Sleeve 20 also includes a deformable bushing 20d located at its second end 20b, the deformable bushing 20d in this case being in the form of a tapping portion. The sleeve 20 includes a deformable portion 20e disposed between a deformable bushing 20d and a flange 20c, spaced apart from a first end 20a and a second end 20b of the sleeve 20. The sleeve 20 also includes a tapped portion 20g disposed between the deformable bushing 20d and the deformable portion 20e. Therefore, the sleeve 20 includes, in sequence between its first end 20a and second end 20b, a flange 20c, a deformable portion 20e, a tapped portion 20g, and a deformable bushing 20d. Although not shown in the figures, between the first and second ends of the sleeve, the sleeve may sequentially include a flange, a threaded portion, a deformable portion, and a deformable bushing.

[0053] As in Figure 2As indicated, after the sleeve 20 is installed in the orifices 12c and 14c of the components 12 and 14, the flange 20c of the sleeve 20 is supported against the widened portion 12d of the orifice 12c of the first component 12 of the assembly. The second end 20b of the sleeve 20, and in particular the deformable portion 20e and the deformable bushing 20d of the sleeve 20, extends beyond the orifice 14c of the second component 14 of the assembly, that is, the second end 20b of the sleeve 20, and in particular the deformable portion 20e and the deformable bushing 20d, extend beyond the first surface 14a of the second component 14. The outer diameter D20 of the sleeve 20 is substantially equal to the inner diameter of the orifices 12c and 14c of the components 12 and 14. Therefore, the sleeve 20 is fitted into the orifices 12c and 14c of the components 12 and 14 in a clearance-free manner. Specifically, the outer diameter of the flange 20c of the sleeve 20 is substantially equal to the inner diameter of the widened portion 12d of the orifice 12c of the first element 12. Similarly, the outer diameter of the body of the sleeve 20 is substantially equal to the inner diameter of the orifice 12c of the first element 12 and the orifice 14c of the second element 14.

[0054] The flange 18i of the actuator 18 is supported against the inner surface of the annular flange 20c of the sleeve 20. The second end 18b of the actuator 18, and in particular the deformable bushing 18d of the actuator 18, extends beyond the orifice 14c of the second element 14 of the assembly, i.e., the second end 18b of the actuator 18, and in particular the deformable bushing 18d of the actuator 18, extends beyond the first surface 14a of the second element 14. The deformable bushing 18d of the actuator 18 is arranged to face the deformable bushing 20d of the sleeve 20.

[0055] After the blind fastening device 10 is inserted, the actuating rod 18, the sleeve 20, and the orifice 12c of the first element 12 and the orifice 14c of the second element 14 are coaxial along the longitudinal axis A. Figure 2 This means that once the blind fastening device 10 is installed in the orifice 12c of the first element 12 and the orifice 14c of the second element 14, the first portion P18 and the second portion D18 of the actuating rod 18 protrude relative to the first surface 12a of the first element 12, and the deformable portion 20e of the sleeve 20, the deformable bushing 20d, and the deformable bushing 18d of the actuating rod 18 protrude relative to the first surface 14a of the second element 14. Therefore, the first portion P18 and the second portion D18 of the actuating rod 18 are located on the accessible side of the assembly, while the deformable bushings 18d and 20d are located on the inaccessible side of the assembly.

[0056] In order to fasten the first element 12 and the second element 14 together, and as Figure 3As indicated, the actuating rod 18 rotates relative to the sleeve 20. More specifically, the actuating rod 18 rotates relative to the sleeve 20 via a first drive nut 18e using a tightening tool (not shown) operated by the operator. The thread of the deformable bushing 18d engages with the tapped portion of the deformable bushing 20d, resulting in the second end of the sleeve 20 being driven along the longitudinal axis A in the assembly direction. The displacement of the deformable bushing 20d of the sleeve 20 is controlled by the tightening of the actuating rod 18, and more specifically by the tightening of the deformable bushing 18d of the actuating rod 18. Thus, after the sleeve 20 is deformed, the second end 20b of the sleeve 20 is a shorter distance from the first surface 14a of the second element 14, whereas before and after the sleeve 20 is deformed, the second end 18b of the actuating rod 18 maintains the same distance from the first surface 14a of the second element 14. Since the widened portion 12d of the first end 20a of the sleeve 20, which abuts against the orifice 12c of the first element 12, is supported, a compressive force is applied to the sleeve 20 between the flange 20c at the first end 20a and the deformable bushing 20d at the second end 20b of the sleeve 20. This causes the deformable portion 20e of the sleeve 20 to deform under the force applied by screwing the actuating rod 18 into the sleeve 20, forming a deformable bulb-shaped portion 20f. The deformable bulb-shaped portion 20f forms a radially expanded portion of the sleeve 20. The expansion of the deformable portion 20e of the sleeve 20 is controlled by screwing the actuating rod 18 into the sleeve 20, and more specifically, by screwing the deformable bushing 18d of the actuating rod 18 into the deformable bushing 20d of the sleeve 20. The deformable portion 20e of the sleeve is designed such that it deforms first when a compressive force applied longitudinally along the longitudinal axis A to the sleeve 20 exceeds a predetermined threshold. The deformable portion 20e of the sleeve 20 can have a smaller thickness than the rest of the sleeve 20 in a non-limiting manner, for example, such that this portion of the sleeve can deform further first under compressive force (i.e., this portion deforms preferentially). The deformed portion 20e is thus supported against the first surface 14a of the second element 14 of the assembly. The outer diameter D20f of the deformable bulb-shaped portion 20f is larger than the outer diameter D20 of the undeformed sleeve 20. This outer diameter D20f is larger than the diameter of the orifice 14c of the second element 14, such that the deformable bulb-shaped portion 20f is supported against the first surface 14a of the second element 14. The elements 12 and 14 of the assembly remain abutted against each other between the flange 20c of the sleeve 20 and the deformable bulb-shaped portion 20f.

[0057] To ensure proper tightening of the actuator 18 in the sleeve 20, the first fracture groove 18f is calibrated to fracture once a first predetermined tightening torque is applied to the first drive nut 18e. This first predetermined tightening torque corresponds to sufficient tightening to allow a predetermined pressure to be maintained on the joint seal 16 of the assembly. Therefore, when the tightening torque applied to the actuator 18 (applied to the first drive nut 18e) exceeds the first predetermined tightening torque, it means that the blind fastening device 10 is correctly installed to ensure pressure on the joint seal 16 between the first element 12 and the second element 14. Figure 4 As shown, the actuating rod 18, and in particular the first drive nut 18e, is rotated relative to the sleeve 20 by means of a tightening tool (not shown in the figure) operated by the operator until the fracture groove 18f breaks. During this rotation of the actuating rod 18, the threaded portion 18c of the actuating rod 18 engages with the tapped portion 20g of the sleeve 20. In fact, in order to form the deformable bulb-shaped portion 20f, and thus the deformable portion 20e, the deformable bushing 18d of the actuating rod 18 engages with the deformable bushing 20d of the sleeve 20; however, once the deformable bulb-shaped portion 20f has been formed, the engagement of the threaded portion 18c of the actuating rod 18 with the tapped portion 20g of the sleeve 20 allows the tightening torque applied to the first drive nut 18e to be limited before the first fracture groove 18f breaks. Therefore, the first part P18 of the actuator rod 18, namely the first drive nut 18e and the first fracture groove 18f, is removed from the blind fastening device 10, and the actuator rod 18 thus retains only its second part D18 and its third part T18.

[0058] To ensure proper re-tightening of the actuator 18 in the sleeve 20, the second fracture groove 18h is calibrated to fracture once a second predetermined tightening torque is applied to the second drive nut 18g. This second predetermined tightening torque corresponds to sufficient tightening necessary to allow proper preloading of the blind fastener 10. Therefore, when the tightening torque applied to the actuator 18, and more specifically to the second drive nut 18g, exceeds the second predetermined tightening torque, it means that the blind fastener 10 is correctly and definitively installed to ensure preloading of the blind fastener 10. Figure 5As shown, the actuating rod 18, and in particular the second drive nut 18g, is rotated relative to the sleeve 20 by means of a tightening tool (not shown in the figure) operated by the operator until the fracture groove 18h breaks. During this rotation of the actuating rod 18 for the purpose of re-tightening the blind fastener 10, the threaded portion 18c of the actuating rod 18 engages with the tapped portion 20g of the sleeve 20. Therefore, the second portion D18 of the actuating rod 18, i.e., the second drive nut 18g and the second fracture groove 18h, is removed from the blind fastener 10, and only the third portion T18 of the actuating rod 18 remains.

[0059] The first predetermined tightening torque is lower than the second predetermined tightening torque, causing the first fracture groove 18f to fracture before the second fracture groove 18h. Therefore, the tightening torque applied to ensure pressure on the seal 16 is lower than the tightening torque applied to ensure preloading of the blind fastening device 10.

[0060] exist Figure 6 The method for installing the blind fastening device 10 is clearly illustrated in the figure.

[0061] First, the method includes step E01 of applying a joint seal 16 between the first element 12 and the second element 14 to be assembled.

[0062] The following steps of the method allow for proper pressing of the joint seal 16 located between the first element 12 and the second element 14 to be assembled, such that the joint seal 16 has a constant thickness between the elements 12 and 14.

[0063] The method includes step E10 of inserting a blind fastening device 10 into coaxial orifices 12c, 14c of a first element 12 and a second element 14 designed for assembly. More specifically, a sleeve 20—in which an actuating rod 18 is already inserted—is inserted into orifice 12c of the first element 12 and orifice 14c of the second element 14. Typically, the actuating rod 18 is inserted into the sleeve 20 before the blind fastening device 10 is installed. It will be understood that the sleeve 20 may be inserted first into orifice 12c of the first element 12 and orifice 14c of the second element 14 without inserting the actuating rod 18 into the sleeve 20, and then the actuating rod 18 may be inserted sequentially into orifice 20h of the sleeve 20.

[0064] The sleeve 20 is inserted into the orifice 12c of the first element 12 to be assembled, starting from the first surface 12a of the element 12 and passing through the second end 20b of the sleeve 20. Then, the sleeve 20 is inserted into the orifice 14c of the second element 14, which is coaxial with the orifice 12c of the first element 12. The second end 20b of the sleeve 20 is open outside the first surface 14a of the second element 14. The flange 20c of the sleeve 20, located at the first end 20a, is supported against the widened portion 12d of the orifice 12c of the first element 12. The sleeve 20 is adjusted in the orifices 12c of the first element 12 and the second element 14, i.e., the sleeve 20 is fitted into the orifices 12c and 14c without play.

[0065] As the blind fastening device 10 is positioned in the orifices 12c and 14c of the components 12 and 14, the second end 18b of the actuating rod 18 is flush with the second end 20b of the sleeve 20. The flange 18i of the actuating rod 18 is supported against the flange 20c of the sleeve 20. The deformable bushing 18d of the actuating rod 18 is positioned facing the deformable bushing 20d of the sleeve 20. The actuating rod 18 is fitted into the orifice 20h of the sleeve 20 with a small clearance to allow the actuating rod 18 to be screwed into the sleeve 20.

[0066] The method then includes a step E20 of deforming the deformable portion 20e of the sleeve 20, the deformation arising from the engagement of the deformable bushing 18d of the actuating rod 18 with the deformable bushing 20d of the sleeve 20. This step E20 of deformation allows the blind fastening device 10 to be fastened to the first element 12 and the second element 14.

[0067] In this case, step E20 includes the sub-step of screwing the threaded deformable bushing 18d of the actuator 18 into the tapped deformable bushing 20d of the sleeve 20, resulting in driving the second end 20b of the sleeve 20 toward the first end 20a of the sleeve 20. This causes compression of the sleeve 20 while the sleeve 20 is held against the first face 12a of the first element 12 by means of its flange 20c, and in particular compression of the deformable portion 20e of the sleeve 20 against the first face 14a of the second element 14. Since the deformable portion 20e is designed to deform after a compressive force greater than a predetermined threshold is applied, this causes the deformable portion 20e to deform when the predetermined threshold is further exceeded to screw the actuator 18 into the sleeve 20, and results in the formation of the deformable portion 20f of the sleeve 20. The threaded deformable bushing 18d of the actuator 18 is screwed into the tapped deformable bushing 20d of the sleeve 20 so that the threaded portion 18c of the actuator 18 can be arranged to face the tapped portion 20g of the sleeve 20.

[0068] The method then includes step E30: screwing the actuator 18 into the sleeve 20 via the first drive nut 18e, and more specifically, screwing the threaded portion 18c of the actuator 18 into the tapped portion 20g of the sleeve 20, until the first fracture groove 18f breaks. More specifically, by means of a tightening tool (not shown in the figure), the operator tightens the first drive nut 18e relative to the sleeve 20, i.e., applies a tightening torque to the first drive nut 18e relative to the sleeve 20, until the first fracture groove 18f shears off. The breaking of the first fracture groove 18f means that the blind fastening device 10 is sufficiently tightened onto the assembly consisting of the first element 12 and the second element 14 to maintain sufficient pressure on the joint seal 16.

[0069] The steps of the method are performed after the joint seal 16 is pressed, creeped, and dried, and the steps of the method allow for proper preloading of the blind fastening device 10.

[0070] The method then includes step E40: re-tightening the actuator 18 in the sleeve 20 by means of the second drive nut 18g, and more specifically, screwing the threaded portion 18c of the actuator 18 into the tapped portion 20g of the sleeve 20 until the second fracture groove 18h breaks. More specifically, by means of a tightening tool (not shown in the figure), the operator tightens the second drive nut 18g about the sleeve 20, i.e., applies a tightening torque to the second drive nut 18g relative to the sleeve 20 until the second fracture groove 18h shears off. The breaking of the second fracture groove 18h means that the blind fastener 10 is sufficiently tightened on the assembly consisting of the first element 12 and the second element 14 to ensure preload on the blind fastener 10.

[0071] Figures 7 to 10 This describes the installation of a second type of blind fastening device for securing structural components of an aircraft together. This second type of blind fastening device, also known as a "pull-to-operate" blind fastening device, is a device that achieves blind fastening through traction and tightening. For clarity, only the differences between the first and second types of blind fastening devices will be described below. Therefore, features not described for the first type of blind fastening device also apply to this second type of blind fastening device.

[0072] The blind fastening device 10 includes an actuating rod 18, which in this case is a traction rod, designed to insert into the sleeve 20.

[0073] The actuating rod 18 includes a deformable bushing 18d located at its second end 18b. In this case, the deformable bushing 18d takes the form of a radially projecting portion (relative to the longitudinal axis A). Apart from the flange 18i, the first fracture groove 18f and the second fracture groove 18h, and the deformable bushing 18d, the actuating rod 18 has a substantially constant diameter equal to the inner diameter of the sleeve 20. Therefore, the diameter of the deformable bushing 18d is larger than the inner diameter of the sleeve 20.

[0074] The sleeve 20 includes a deformable bushing 20d located at its second end 20b, the deformable bushing 20d being in the form of a radially expanded portion in this case. The sleeve 20 also includes a tapped portion 20g disposed between the flange 20c and the deformable portion 20e. Thus, the sleeve 20 includes, in sequence between its first end 20a and second end 20b, a flange 20c, a tapped portion 20g, a deformable portion 20e, and a deformable bushing 20d.

[0075] like Figure 8 This means that, because the diameter of the deformable bushing 18d of the actuator 18 is larger than the inner diameter of the sleeve 20, the deformable bushing 18d of the actuator 18 causes the sleeve 20 to deform at the deformable bushing 20d. The deformable bushing 20d of the sleeve 20 takes the form of a protrusion, i.e., a radially expanded portion. The deformable bushing 18d of the actuator 18 causes partial deformation of the sleeve 20, and forms a partial radial expansion of the sleeve 20 relative to the deformable bushing 18d of the actuator 18.

[0076] In order to fasten the first element 12 and the second element 14 together, and as Figure 9This indicates that the actuating rod 18 translates relative to the sleeve 20, wherein the sleeve 20 is held in the orifices 12c, 14c of the elements 12, 14. More specifically, the actuating rod 18 is pulled relative to the sleeve 20 along the longitudinal axis A in a direction opposite to that of the sleeve 20. Then, the flange 18i of the actuating rod 18 is no longer supported against the flange 20c of the sleeve and is spaced apart from the flange 20c of the sleeve. This traction on the actuating rod 18 results in the portion of the sleeve 20 including the second end 20b of the sleeve 20 being driven along the longitudinal axis A in the direction of assembly. After the sleeve 20 is deformed, the second end 20b of the sleeve 20 and the second end 18b of the actuating rod 18 are a short distance away from the first surface 14a of the second element 14. With the first end 20a of the sleeve 20 supported against the widened portion 12d of the orifice 12c of the first element 12, the traction of the actuating rod 18 results in a compressive force being applied between the first end 20a and the second end 20b of the sleeve 20. This causes the deformable portion 20e of the sleeve 20 to deform under the force applied by the traction of the actuating rod 18 relative to the sleeve 20, forming a deformable bulb-shaped portion 20f. The deformable bulb-shaped portion 20f blocks the sleeve 20 supported against the first surface 14a of the first element 14. The radial expansion of the deformable portion 20e of the sleeve 20 is controlled by the traction of the actuating rod 18 relative to the sleeve 20, and more specifically, by the traction of the deformable bushing 18d of the actuating rod 18 relative to the deformable bushing 20d of the sleeve 20. The traction on the actuator rod 18 also allows the threaded portion 18c of the actuator rod 18 to be arranged facing the tapped portion 20g of the sleeve 20. Once the deformed bulb-shaped portion 20f has been formed, and as... Figure 10 As shown, the actuating rod 18, and in particular the first drive nut 18e, is rotated relative to the sleeve 20 by means of a tightening tool (not shown in the figure) operated by the operator until the flange 18i of the actuating rod 18 is supported against the flange 20c of the sleeve 20. During this rotation of the actuating rod 18, the threaded portion 18c of the actuating rod 18 engages with the tapped portion 20g of the sleeve 20.

[0077] The method for installing the second type of blind fastening device 10 differs from the method for installing the first type of blind fastening device in that:

[0078] - During step E10, when the blind fastening device 10 is inserted into the orifices 12c, 14c of the first element 12 and the second element 14 designed to be assembled, the deformable bushing 18d of the actuating rod 18 causes the sleeve 20 to deform at its deformable bushing 20d.

[0079] In this case, step E20, which deforms the deformable portion 20e of the sleeve 20, includes a sub-step of pulling the actuating rod 18 relative to the sleeve 20. This results in the second end 20b of the sleeve 20 being driven in the direction of the first end 20a of the sleeve 20. With the sleeve 20 held against the first surface 12a of the first element 12 by its flange 20c and the deformable bushing 18d forming the radial protrusion of the actuating rod 18 being pulled within the deformable bushing 20d forming the radial expansion portion of the sleeve 20, this allows compression of the sleeve 20 to occur, and in particular, compression of the deformable portion 20e of the sleeve 20 against the first surface 14a of the second element 14. Since the deformable portion 20e is designed to deform further when a compressive force greater than a predetermined threshold is applied, this causes deformation of the deformable portion 20e and the formation of the deformable portion 20f of the sleeve 20 when the predetermined threshold is further exceeded to pull the actuating rod 18 relative to the sleeve 20.

[0080] Figures 11 to 13 This indicates that another type of blind fastening device is installed by traction and tightening.

[0081] The sleeve 20 includes a deformable bushing 20d located at its second end 20b, which in this case takes the form of a support surface. A deformable portion 20e of the sleeve 20 is arranged at the second end 20b of the sleeve 20.

[0082] like Figure 12 This means that after the actuator 18 is installed in the sleeve 20, the deformable bushing 18d of the actuator 18 extends beyond the second end 20b of the sleeve 20. Since the diameter of the deformable bushing 18d of the actuator 18 is larger than the inner diameter of the sleeve 20, and the actuator 18 protrudes relative to the sleeve 20, the deformable bushing 18d of the actuator 18 is supported against the deformable bushing 20d of the sleeve 20.

[0083] In order to fasten the first element 12 and the second element 14 together, and as Figure 13This indicates that the actuating rod 18 translates relative to the sleeve 20, wherein the sleeve 20 is held in the orifices 12c, 14c of the elements 12, 14. More specifically, the actuating rod 18 is pulled relative to the sleeve 20 along the longitudinal axis A in a direction opposite to that of the sleeve 20. This pulling of the actuating rod 18 results in the portion of the sleeve 20 including the second end 20b of the sleeve 20 being driven along the longitudinal axis A in the direction of assembly. With the first end 20a of the sleeve 20 supported against the widened portion 12d of the orifice 12c of the first element 12, the traction of the actuating rod 18 results in a compressive force being applied between the first end 20a and the second end 20b of the sleeve 20. This causes the deformable portion 20e of the sleeve 20 located at the second end 20b of the sleeve 20 to deform under the force applied by the traction of the actuating rod 18 relative to the sleeve 20, forming a deformable bulb-shaped portion 20f. The deformable bulb-shaped portion 20f blocks the sleeve 20 supported against the first surface 14a of the first element 14. The radial expansion of the deformable portion 20e of the sleeve 20 is controlled by the traction of the actuating rod 18 relative to the sleeve 20, and more specifically, by the traction of the deformable bushing 18d of the actuating rod 18 relative to the deformable bushing 20d of the sleeve 20.

[0084] The method for installing the third type of blind fastening device 10 differs from the method for installing the second type of blind fastening device in that:

[0085] - During step E10, when the blind fastening device 10 is inserted into the orifices 12c, 14c of the first element 12 and the second element 14 designed to be assembled, the deformable bushing 18d of the actuating rod 18 is supported against the deformable bushing 20d of the sleeve 20.

[0086] In this case, step E20, which deforms the deformable portion 20e of the sleeve 20, includes a sub-step of pulling the actuating rod 18 relative to the sleeve 20. This results in the second end 20b of the sleeve 20 being driven in the direction of the first end 20a of the sleeve 20. With the sleeve 20 held against the first surface 12a of the first element 12 by its flange 20c and the deformable bushing 18d forming the radial protrusion of the actuating rod 18 pulled relative to the deformable bushing 20d forming the support surface of the sleeve 20, this allows compression of the sleeve 20 to occur, and in particular, compression of the deformable portion 20e of the sleeve 20 against the first surface 14a of the second element 14. Since the deformable portion 20e is designed to deform further when a compressive force greater than a predetermined threshold is applied, this causes deformation of the deformable portion 20e when the predetermined threshold is further exceeded to pull the actuating rod 18 relative to the sleeve 20, forming a deformable portion 20f of the sleeve 20.

[0087] exist Figure 14 The image shows an aircraft 100, which includes an assembly consisting of a first element 12 and a second element 14 formed by a blind fastening device 10 according to the invention. The blind fastening device according to the invention has been described as being used to fasten two elements of an aircraft; however, it will be understood that the blind fastening device according to the invention can be used to fasten more than two elements together without departing from the scope of the invention. Furthermore, the elements to be assembled can be different types of components of the aircraft to be assembled, such as, for example and in a non-limiting manner, structural components, floor components, cabin components, and fuel tank components of the aircraft.

Claims

1. A blind fastening device (10) for fastening an assembly consisting of a first element (12) and a second element (14), wherein a joint seal (16) is positioned between the first element (12) and the second element (14), the first element (12) including an orifice (12c) having a first inner diameter and the second element (14) including an orifice (14c) having the first inner diameter, the blind fastening device (10) comprising: An actuating rod (18) having a first end (18a) and a second end (18b), and the actuating rod (18) comprising: a first drive nut (18e) located at the first end (18a) of the actuating rod (18), a first fracture groove (18f) located between the first drive nut (18e) and the second end (18b) of the actuating rod (18), a threaded portion (18c) located between the first fracture groove (18f) and the second end (18b) of the actuating rod (18), and a deformable bushing (18d) located at the second end (18b) of the actuating rod (18). A sleeve (20) is insertable into the orifice (12c) of the first element (12) and the orifice (14c) of the second element (14), and the sleeve (20) has a first outer diameter (D20) substantially equal to the first inner diameter. The sleeve (20) is threaded to the actuating rod (18) and has a first end (20a) and a second end (20b). The sleeve (20) includes a portion located between the first end (20a) and the second end (20b) of the sleeve (20). The sleeve (20) comprises a tapped portion (20g), a deformable bushing (20d) located at the second end (20b) of the sleeve (20), and a deformable portion (20e) located between the first end (20a) and the second end (20b) of the sleeve (20). The deformable portion (20e) is configured to deform radially when the deformable bushing (18d) of the actuating rod (18) engages with the deformable bushing (20d) of the sleeve (20) until the sleeve (20) has a second outer diameter (D20f) larger than the first outer diameter (D20). The first fracture groove (18f) is configured to fracture when the tightening torque applied to the first drive nut (18e), causing the threaded portion (18c) of the actuator rod (18) to engage with the tapped portion (20g) of the sleeve (20), exceeds a first predetermined torque. The actuator (18) includes a second drive nut (18g), which is followed by a second fracture groove (18h) located between the first fracture groove (18f) and the threaded portion (18c). The second fracture groove (18h) is configured to fracture when the retightening torque applied to the second drive nut (18g) exceeds a second predetermined torque greater than the first predetermined torque.

2. The blind fastening device (10) according to claim 1, wherein, The deformable bushing (18d) of the actuator (18) is threaded, and the deformable bushing (20d) of the sleeve (20) is tapped.

3. The blind fastening device (10) according to claim 1, wherein, The deformable bushing (18d) of the actuator (18) is in the form of a radial protrusion, and the deformable bushing (20d) of the sleeve (20) is in the form of a radial expansion.

4. The blind fastening device (10) according to claim 1, wherein, The deformable bushing (18d) of the actuator (18) is in the form of a radial protrusion, and the deformable bushing (20d) of the sleeve (20) is in the form of a support surface, and the deformable bushing (18d) of the actuator (18) is supported against the support surface.

5. A method for installing a blind fastening device (10) according to any one of the preceding claims, the blind fastening device (10) being used to fasten the assembly consisting of the first element (12) and the second element (14), the method comprising: Step (E10): Insert the blind fastening device (10) into the orifice (12c) of the first element (12) and the orifice (14c) of the second element (14); Step (E20): The deformable bushing (18d) of the actuating rod (18) is engaged with the deformable bushing (20d) of the sleeve (20) to radially deform the deformable portion (20e) of the sleeve (20) until the sleeve (20) has a second outer diameter (D20f) larger than the first outer diameter (D20), wherein the engagement of the deformable bushing (18d) of the actuating rod (18) and the deformable bushing (20d) of the sleeve (20) enables the threaded portion (18c) of the actuating rod (18) to be arranged facing the tapped portion (20g) of the sleeve (20). Step (E30): Tighten the threaded portion (18c) of the actuator rod (18) into the tapped portion (20g) of the sleeve (20) using the first drive nut (18e) until the first fracture groove (18f) breaks. The method further includes: Step (E40): Tighten the threaded portion (18c) of the actuator rod (18) in the tapped portion (20g) of the sleeve (20) by means of the second drive nut (18g) until the second fracture groove (18h) breaks.

6. The method for installing the blind fastening device (10) according to claim 5, wherein, The deformable bushing (18d) of the actuating rod (18) is threaded, and the deformable bushing (20d) of the sleeve (20) is tapped. The step (E20) of engaging the deformable bushing (18d) of the actuating rod (18) with the deformable bushing (20d) of the sleeve (20) includes the following sub-step: screwing the deformable bushing (18d) of the actuating rod (18) into the deformable bushing (20d) of the sleeve (20), such that the thread of the deformable bushing (18d) of the actuating rod (18) engages with the tapped part of the deformable bushing (20d) of the sleeve (20).

7. The method for installing the blind fastening device (10) according to claim 5, wherein, The deformable bushing (18d) of the actuating rod (18) is in the form of a radial protrusion, and the deformable bushing (20d) of the sleeve (20) is in the form of a radial expansion portion. The step (E20) of engaging the deformable bushing (18d) of the actuating rod (18) with the deformable bushing (20d) of the sleeve (20) includes the following sub-step: pulling the deformable bushing (18d) of the actuating rod (18) within the deformable bushing (20d) of the sleeve (20) such that the radial protrusion of the deformable bushing (18d) of the actuating rod (18) engages with the radial expansion portion of the deformable bushing (20d) of the sleeve (20).

8. The method for installing the blind fastening device (10) according to claim 5, wherein, The deformable bushing (18d) of the actuating rod (18) is in the form of a radial protrusion, and the deformable bushing (20d) of the sleeve (20) is in the form of a support surface. The step (E20) of engaging the deformable bushing (18d) of the actuating rod (18) with the deformable bushing (20d) of the sleeve (20) includes the following sub-step: pulling the deformable bushing (18d) of the actuating rod (18) in the deformable bushing (20d) of the sleeve (20) such that the radial protrusion of the deformable bushing (18d) of the actuating rod (18) engages with the support surface of the deformable bushing (20d) of the sleeve (20).

Images