Fastening assembly for a turbine blade

Abstract

The present invention relates to an assembly for a turbine engine blade, the assembly comprising: a fastener (9) defining a recess (10) for receiving a blade root (7); and a clamping device (32) for clamping the blade root (7) onto the fastener (9) when the blade root (7) is received in the recess (10), wherein the clamping device (32) comprises: at least one clamping element (34; 36) adapted to be simultaneously supported on the blade root (7) and the fastener (9) in the recess (10) to apply a clamping force on the blade root (7), the clamping element (34; 36) defining a threaded hole; an elastic layer (44) arranged to be supported on the blade root in the recess; and a rod (38) including threads engaging with the threaded hole such that rotation of the rod (38) relative to the clamping element causes a change in the clamping force applied by the clamping element to the blade root.

Description

Technical Field

[0001] The present invention relates to an assembly for a turbine, the assembly being used to attach the turbine blades to fasteners. Background Technology

[0002] A conventional fan includes a blade fastener that defines a recess for receiving the root of the blade. The blade fastener includes two opposing flanks that together define a channel into the recess and form a stop to prevent the root from leaving the recess through this channel. The blade root can engage with the recess through the two opposing entry channels.

[0003] However, in some fan configurations, the blades may experience completely isolated turbulent aerodynamic flows, which generates vibrational excitation across a wide frequency band. Due to this vibrational excitation, the blade root is prone to oscillation within the recess that receives it. However, this oscillation increases the risk of damage to the blade or the fasteners defining the recess.

[0004] In particular, document EP2425100 has proposed inserting a shim with a blade root into such a recess. The deformable shim is forced into the recess between the blade root and the fastener by hand or with a mallet. When the fan stops, this force-driven insertion allows the shim to be supported simultaneously on the blade root and the fastener based on a support force of approximately 50 kg.

[0005] However, this type of shim cannot systematically prevent the aforementioned oscillation phenomenon. Specifically, when the fan rotates at its nominal speed, the blade root rises inside the recess under the action of centrifugal force, thereby increasing the space between the blade root and the bottom of the recess. This causes the force exerted by the shim on the fastener to decrease when the shim returns to its initial unforced geometry, resulting in oscillation of the blade root, or even rotation of the blade. Summary of the Invention

[0006] The purpose of this invention is to more effectively prevent turbine blade root oscillation (especially at high speeds).

[0007] Therefore, according to a first aspect, an assembly for turbine blades is provided, the assembly comprising:

[0008] • Fasteners, the fasteners defining a recess for receiving the root of the blade, and

[0009] • A clamping device for clamping the blade root onto the fastener when the blade root is in the recess, the clamping device comprising:

[0010] At least one clamping element adapted to be simultaneously supported in a recess on both the blade root and the fastener to apply a clamping force on the blade root, the clamping element defining a threaded hole, wherein the clamping element includes an elastic layer arranged to be supported in the recess on the blade root.

[0011] The rod includes threads that interact with a threaded hole, such that rotation of the rod relative to the clamping element causes a change in the clamping force applied by the clamping element to the root of the blade.

[0012] By altering the force applied by the clamping element through the threaded rod, a higher clamping force can be achieved than the simple support force obtained by inserting shims under force using hands or a mallet. Therefore, even if the clamping element experiences centrifugal force during turbine operation, causing a reduction in the clamping force applied to the fastener, this reduction is insufficient to significantly prevent the clamping element from firmly clamping the fastener. This is why the clamping element prevents blade wobbling even at high speeds.

[0013] The elastic layer element is compressible to press against the blade root, thereby maintaining the stress on the blade (the blade root is displaced under centrifugal force and / or by aerodynamic stress). As defined in documents EP2425100 or EP2009245, the elastic support force for the stress at the blade root is approximately 10 to 20 times the elastic restoring force of the elastic deformable gasket.

[0014] The components in the first aspect may also include the following optional features, which may be used individually or in combination, where feasible.

[0015] Preferably:

[0016] The clamping element is configured to displace relative to the fastener as the rod rotates relative to the fastener.

[0017] • The shapes of the fastener and the clamping element are adapted to allow the clamping element to be displaced relative to the fastener so as to cause a change in the clamping force applied by the clamping element at the root.

[0018] Preferably, the clamping element is supported on the bottom surface of the recess, the bottom surface of the recess forming a slope inclined relative to the rotation axis of the rod.

[0019] Preferably, the clamping element includes a metal portion defining the threaded hole.

[0020] Preferably, the thickness of the elastic layer ranges from 1 mm to 4 mm.

[0021] Preferably, the clamping device includes a stop that limits the translational trajectory of the rod relative to the fastener along the rotation axis of the rod.

[0022] Preferably, the component includes a first locking portion that prevents the root from leaving the recess, the first locking portion including a stop.

[0023] Preferably, the rod includes an end portion adapted to engage with a tool and be rotatably driven by the tool, the end portion being, for example, provided with a spline.

[0024] Preferably, the component includes an anti-rotation device adapted to prevent the rod from rotating relative to the fastener.

[0025] Preferably, the anti-rotation device includes a second locking part to prevent the root from leaving the recess.

[0026] Preferably, the anti-rotation device further includes:

[0027] • The end of the rod,

[0028] • A detachable seat adapted to engage with the end rather than with the tool, and the detachable seat is also used to engage with the second locking part.

[0029] Preferably:

[0030] The clamping device includes two clamping elements, each adapted to be simultaneously supported in the recess on the root and the fastener to apply a clamping force on the root, and each clamping element defines a threaded hole.

[0031] The rod includes two threads that interact with the two threaded holes respectively, such that rotation of the rod relative to the clamping elements causes a change in the same sign of the clamping force applied by the two clamping elements to the root.

[0032] Preferably:

[0033] The two clamping elements are configured to displace relative to the fastener as the rod rotates relative to the fastener.

[0034] The fastener and the two clamping elements have suitable shapes such that the displacement of each of the two clamping elements relative to the fastener causes a change in the clamping force applied by the two clamping elements to the root.

[0035] Preferably, the two clamping elements are configured to move away from each other or toward each other as the rod rotates relative to the fastener about a rotation axis. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become apparent from the following description, which is purely illustrative and non-limiting and must be read with reference to the accompanying drawings, in which:

[0037] · Figure 1 This is a side view of the turbine.

[0038] · Figure 2 This is a side perspective view of a fastener for a turbine blade according to one embodiment.

[0039] · Figure 3 A clamping device according to one embodiment and with Figure 2 A side perspective view of the locking portion where the fasteners interact.

[0040] · Figure 4 yes Figure 3 The image shows a top view of the clamping device and locking mechanism.

[0041] · Figure 5 yes Figure 3 An enlarged bottom view of a portion of the clamping device and one of the locking parts shown.

[0042] · Figures 6 to 10 It is a view of fasteners and clamping devices at different stages of the assembly.

[0043] · Figure 11 Is with Figure 2 The image shows a side view of the blade root where the clamping device and locking part interact.

[0044] In all the accompanying drawings, similar elements have the same reference numerals. Detailed Implementation

[0045] Reference Figure 1 The turbine includes an open rotor type engine 1. Engine 1 includes a pod 2 for attachment to the fuselage of the aircraft and a ductless fan 3. Fan 3 includes two counter-rotating fan rotors 4 and 5. In other words, when engine 1 is running, rotors 4 and 5 are driven to rotate relative to pod 2 about the same axis of rotation X (coinciding with the main axis of the engine).

[0046] like Figure 1 The engine 1 shown is in a configuration commonly referred to as a "propeller" (i.e., fan 3 is located within the power generator, and the air inlet is located upstream). Figure 1 (Right side).

[0047] However, alternatively, engine 1 can be in a "tractor" configuration (i.e., the fan is positioned upstream of the power generator, and the air inlet is located in front of, between, or directly behind the two fan rotors). Engine 1 can still have different configurations, such as a configuration with fan rotors including movable blades and a fan stator including fixed blades (USF configuration), or a configuration with a single fan rotor (TP configuration). The invention is also applicable to ducted fan turbines, but also has variable configurations.

[0048] exist Figure 1 In each fan rotor 4, 5, there is a hub 6 and a plurality of blades 7, the hub being rotatably mounted relative to the pod 2, and the blades being attached to the hub 6. The blades 7 extend substantially radially relative to the axis of rotation X of the hub.

[0049] In this application, upstream and downstream are defined with reference to the normal flow direction of gas in rotors 4 and 5 and through the turbine. Furthermore, the axis A of rotors 4 and 5 is referred to as their axis of rotation. The axial direction corresponds to the direction of axis A, and the radial direction is the direction perpendicular to and through this axis. Additionally, the circumferential direction corresponds to the direction perpendicular to axis A and does not cross it. Unless otherwise specified, the terms "inner" and "outer" will be used with reference to the radial direction, such that the inner portion or surface of an element is closer to axis A than the outer portion or surface of the same element.

[0050] Reference Figure 2 For each blade 7, the fan 3 includes a fastener 9. The fastener 9 is rotatably mounted relative to the hub 6 about a setting axis Y. More precisely, the fastener 9 is rotatably mounted within a housing formed in the hub 6 by means of a ball or other rolling element.

[0051] The fastener 9, which may also be referred to as a “pivot” in the literature, defines a recess 10 to receive the root of the blade 7, which is, for example, in the shape of a swallowtail.

[0052] Specifically, the fastener 9 includes two side wings 12, 14 that define a radial opening in the recess 10 between them, the radial opening being opposite to the bottom of the recess 10. The two side wings 12, 14 are inclined toward each other and form a support surface.

[0053] The recess 10 extends in the Z direction between two opposing access channels 16, 18 defined by the fastener 9. One of the two access channels 16, 18 is located on the leading edge side of the blade, and the other access channel is located on the trailing edge side of the blade. Through one or the other of these opposing access channels 16, 18, the blade root can be translated into the recess 10.

[0054] A pair of opposing grooves 20 are formed in the side wings 12, 14 at the entry channel 16. It will then be seen that the locking part can engage in the groove 20 to close the entry channel 16 and prevent the blade root in the recess 10 from leaving the recess 10.

[0055] Another pair of opposing grooves 22 are formed in the side wings 12, 14 at the entry channel 18. As will be seen below, another locking part can engage in the groove 20 to close the entry channel 18 and prevent the blade root in the recess 10 from leaving the recess 10 via the entry channel 18.

[0056] The bottom of the recess 10 includes sections with different slopes (this is in...). Figure 11 The two bottom surfaces 24 and 26 are also visible in the middle.

[0057] For example, each bottom surface 24, 26 has a straight profile in a plane parallel to the plane (Y, Z). In the remainder of this document, the term "sagittal" profile will be used to refer to the profile of a portion of the fastener in a plane parallel to the plane (Y, Z).

[0058] In the embodiment shown in the accompanying drawings, the bottom surfaces 24 and 26 are inclined relative to each other so as to meet at a vertex, which forms the point closest to the upper radial opening of the recess. In other words, as these bottom surfaces 24 and 26 extend toward the center of the recess 10, the bottom surfaces rise toward the upper radial opening. In other words, as these bottom surfaces 24 and 26 extend toward the two opposing entry channels 16 and 18 of the recess 10, these bottom surfaces descend.

[0059] The fastener 9 also includes a wall 28 that projects radially outward from the bottom of the recess 10. The wall 28 defines the lower half of the hole.

[0060] The apex of wall 28 defines the radially inward edge of the entrance channel 18.

[0061] Blind holes 30 extend to the apex of the wall 28. For example, two blind holes 30 are threaded.

[0062] Fastener 9 is made of metal, preferably titanium.

[0063] Reference Figure 3 and Figure 4 The clamping device 32 has the function of clamping the blade root onto the fastener 9 when the blade root is received in the recess 10.

[0064] The clamping element 32 includes two clamping elements 34 and 36 and a lever 38.

[0065] The clamping element 34 includes a portion 40 defining a threaded hole. This portion 40 is made of a metallic or composite material. The portion 40 defines a lower support surface 42 of the clamping element 34 on the bottom surface 24.

[0066] The clamping element 34 also includes an elastic layer 44 that defines an upper support surface 46 of the clamping element 34 on the blade root received in the recess 10.

[0067] For example, the elastic layer 44 has a honeycomb structure.

[0068] Preferably, the elastic layer 44 is made of an elastomer or glass fiber material.

[0069] In particular, when part 40 is made of metal, the elastic layer 44 can be bonded to part 40. When part 40 is made of composite material, the elastic layer forms part of that part (especially in the case of a honeycomb structure).

[0070] The thickness of the elastic layer 44 ranges from 1 mm to 4 mm, preferably from 2 mm to 3 mm. The support surfaces 42 and 46 have straight, non-parallel sagittal profiles.

[0071] The clamping element 34 is H-shaped, which allows it to be stably supported at the root of the blade as long as the weight is not too great.

[0072] Clamping element 36 includes the same features as clamping element 34 described above. However, note that the lower support surface of element 36 is intended to rest on bottom surface 26. Furthermore, the threaded hole of clamping element 36 is threaded in the opposite direction to the threaded hole of clamping element 34.

[0073] The lever 38 includes a thread 48 that interacts with a threaded hole in the clamping element 34 and a thread 50 that interacts with a threaded hole in the clamping element 40. The two threads 48 and 50 extend on two separate portions of the lever 38. These two threads are arranged in two opposite directions. Therefore, rotation of the lever 38 relative to the clamping elements 34 and 36 drives the two clamping elements 34 and 36 to separate or converge relative to each other in a direction parallel to the axis of rotation of the lever 38.

[0074] The rod has a first end adapted to engage with a tool, for example, the rod is rotatably driven by the tool. For this purpose, the first end is provided with a spline (the spline is in...). Figure 9 (See in the middle).

[0075] The rod has a second end opposite the first end with regard to its two threads 48, 50.

[0076] The second end includes two flanges 52 and 54 spaced apart from each other. The two flanges 52 and 54 are separated from each other by a distance greater than the thickness of the wall 28 (measured parallel to the axis Z).

[0077] Figure 3 and Figure 4 Two locking parts, 56 and 58, are also shown.

[0078] The locking part 56 functions to close the first access channel 16 leading to the recess 10. The locking part 56 includes a generally trapezoidal plate 60 adapted to interact with the recess 20 to achieve the aforementioned closure. The locking part 56 includes two tabs 62 projecting from the plate 60. The two tabs 62 are parallel to each other.

[0079] Reference Figure 5 The removable seat 64 is adapted to engage with the first end of the rod 38, such that the seat can translate parallel to the axis of the rod 38. The seat 64 has a splined inner surface that interacts with the first end of the rod 38 and has a shape adapted to engage between the tabs 62.

[0080] The tab 62 defines two opposing grooves.

[0081] Furthermore, a locking element 66 in the form of a snap ring may be supported in two opposing grooves formed in the tab 62.

[0082] Back Figure 3 and Figure 4 The locking portion 58 functions to close the second access channel 18 of the recess 10. The locking portion 58 includes a plate 68 adapted to interact with a groove 22 formed in the fastener 9 to achieve this closure. Furthermore, the locking portion 58 includes a base 70 defining an upper half of the hole.

[0083] In addition, the base 70 defines two threaded through holes, and two screws 72 engage in the two threaded through holes.

[0084] The different components described above are assembled together in the following manner, from such Figure 2 Start with fastener 9 as shown.

[0085] Reference Figure 6 The clamping device 32 is placed in the recess 10 such that the lower support wall 42 of the clamping element 34 is placed on the bottom surface 24, and the lower wall of the clamping element 36 is placed on the bottom surface 26 at the same time.

[0086] Furthermore, the clamping device 32 is arranged such that the rod 38 passes through the semi-hole formed by the wall 28. Thus, the wall 28 is located between the two flanges 52 and 54. In addition, the flange 52 is located between the wall 28 and the clamping element 36.

[0087] Reference Figure 7 The locking part 58 then engages in the recess 22 to, for example, close the access channel 18 leading to the recess 10. The screw 72 is engaged in the blind holes 30 and screwed into these holes 30 to attach the locking part 58 to the fastener 9.

[0088] Then, the base 70 and the wall 24 together define the hole through which the rod 38 passes between the two flanges 52 and 54. These four elements, especially the base 70, thus constitute stops, each of which restricts the displacement trajectory of the rod 38 along the Z-axis.

[0089] From this stage onwards, the bottom surfaces 24 and 26 form two ramps that are inclined relative to the axis of rotation of rod 38.

[0090] Reference Figure 8 The blade root 7 then engages with the recess 10 via the open access channel 16. The locking part 58 prevents the blade root from exiting the recess 10 via the access channel 18.

[0091] Reference Figure 9 The first end of rod 38 is still accessible via access channel 16 at this stage.

[0092] Engage the tool (not shown) with the first end of the rod 38. The tool may be manual or motor-driven. Then use the tool to rotate the rod 38 relative to the fastener 9 and clamping elements 34, 36 in a first rotational direction.

[0093] Rotation of the rod 38 in the first direction of rotation causes displacement of the clamping element 34 in the recess 10 relative to the fastener 9. The clamping element 34 then climbs the ramp formed by the bottom surface 24, bringing it closer to the blade root 7 engaged in the recess 10 and pressing the elastomer 44 against the blade root. In other words, the clamping force applied by the clamping element 34 increases as the rod rotates in the first direction of rotation. When the ramp formed by the bottom surface 24 has a straight profile, the displacement of the clamping element 34 relative to the fastener 9 is a translation parallel to the ramp.

[0094] The rotation of rod 38 in the first direction of rotation also causes the clamping element 36 in the recess 10 to displace relative to the fastener 9. The clamping element 36 then climbs the ramp formed by the bottom surface 26, bringing it closer to the blade root engaged in the recess 10 and pressing the elastic body of the clamping element 36 against the blade root. In other words, the clamping force applied by the clamping element 36 increases as the rod rotates in the first direction of rotation. When the ramp formed by the bottom surface 26 has a straight profile, the displacement of the clamping element 36 relative to the fastener 9 is a translation parallel to the ramp.

[0095] Therefore, rod 38 rotates until the clamping force on blade root 7 is high enough to prevent the blade root from swinging in the recess during turbine operation.

[0096] To reduce the clamping force, it is sufficient to rotate rod 38 in a second rotation direction opposite to the first rotation direction mentioned above. In this case, the two clamping elements descend along their respective ramps 24, 26 and move away from each other, which relaxes the elastomer.

[0097] Finally, during the rotation of rod 38, the changes in the force applied to the blade root 7 by clamping element 34 and the changes in the force applied to the blade root 7 by clamping element 36 have the same sign: either both forces increase simultaneously, or both forces decrease simultaneously.

[0098] Furthermore, it should be noted that when the rod is rotated by the tool, the rod 38 will slightly displace in the radial direction due to the inclined nature of the bottom surfaces 24 and 28. Of course, the hole through which the rod 38 passes and is formed by the wall 28 and the locking part 58 has a suitable size to allow this displacement.

[0099] Specifically, the elastic layer 44 is advantageously combined with the rod 38 and the two clamping elements 34, 36. Specifically, the stiffness of the rod 38 constitutes a prestress. When the blade root moves radially away, the tensile prestress on the rod 38 relaxes, and by still being under tensile stress, the clamping elements 34, 36 converge towards each other, and then the clamping elements 34, 36 follow the blade root.

[0100] Reference Figure 10 The locking part 56 then engages in the groove 20 (engagement occurs in the centrifugal direction, i.e., in...) Figure 10 (From bottom to top) to achieve the engagement position.

[0101] In the engaged position, the locking part 56 closes the access channel 16, thus preventing the blade root from dislodging from the recess via the access channel 16. Furthermore, in this engaged position, the two tabs 62 of the locking part 56 together define a channel toward the first end of the rod 38.

[0102] A seat 64 engages in the channel to interact with the first end of the rod 38, replacing the tool mentioned above. Simultaneously, the seat is attached to the plate 68 relative to the fastener 9. Furthermore, two tabs 62 lock the seat 64 relative to the fastener 9 in rotation, and thus lock the rod 38 relative to the fastener 9 in rotation.

[0103] Finally, the first end of the rod 38, the locking part 58, and the seat 64 together form an anti-rotation device suitable for preventing the rod 38 from rotating relative to the fastener 9. This is advantageous because it achieves both the function of locking the blade root in the recess and the anti-rotation function of preventing the rod from rotating, with a small number of parts.

[0104] Then, the locking element 66 engages in two opposing grooves formed in the two tabs 62 to prevent the locking element from dislodging from the seat 64 during the passage defined between the two tabs 62.

[0105] Blade 7 is now securely attached to fastener 9 and ready for use.

[0106] Reference Figure 11 The following points should be noted:

[0107] The axis of rotation of shaft 38 is parallel to the following surface of blade root 7: clamping elements 34 and 36 are supported on this surface;

[0108] • The lower support surfaces of clamping elements 34 and 36 are inclined relative to the following elements: the axis of rotation of rod 38 and the root surface of the blade on which the clamping elements are supported.

[0109] The turbine components described above with reference to the accompanying drawings may be modified. In particular:

[0110] Although the presence of two clamping elements helps to better distribute the clamping force at the blade root, a single clamping element is sufficient to achieve a very high clamping force.

[0111] • In a modification not shown, when two clamping elements are present in the recess, an increase in the force applied to the blade root by the two clamping elements can be achieved when the two clamping elements are close to each other, as shown, or conversely, when they are far apart from each other. In this modification not shown, the two bottom surfaces (on which the two clamping elements are respectively supported) together form a hollow portion at the center of the bottom of the recess.

[0112] In the illustrated embodiment, the elastomer is pressed against the blade root, which avoids damage to the blade root. However, in a modification not shown, the elastomer may be positioned against the bottom of the recess 10.

Claims

1. An assembly for turbine blades, the assembly comprising: ● Fastener (9), which defines a recess (10) for receiving the blade root (7), and ● Clamping device (32), the clamping device being used to clamp the blade root (7) onto the fastener (9) when the blade root (7) is in the recess (10), the clamping device (32) comprising: A clamping element (34) is configured to be supported simultaneously in a recess (10) on the blade root (7) and the fastener (9) to apply a clamping force on the blade root (7). The clamping element (34) defines a threaded hole, wherein... The clamping element includes an elastic layer arranged in the recess and supported on the blade root (7), and compressed by the blade root (7) when a clamping force is applied. The rod (38) includes a thread connecting to the threaded hole, such that rotation of the rod (38) relative to the clamping element causes a change in the clamping force applied by the clamping element to the root (7) of the blade, and o Stop (70) that limits the travel of the rod (38) relative to the fastener (9) along the axis of rotation of the rod (38).

2. The component according to claim 1, wherein, ●The clamping element (34) is configured to displace relative to the fastener (9) when the rod (38) rotates relative to the fastener (9). ●The fastener (9) and the clamping element (34) are configured such that displacement of the clamping element (34) relative to the fastener (9) causes a change in the clamping force applied by the clamping element (34) to the root.

3. The component according to claim 1, wherein, The clamping element (34) is supported on the bottom surface (24) of the recess (10), the bottom surface of which forms a slope inclined relative to the rotation axis of the rod (38).

4. The component according to claim 1, wherein, The clamping element (34) includes a metal portion (40) defining the threaded hole.

5. The component according to claim 1, wherein, The thickness of the elastic layer ranges from 1 mm to 4 mm.

6. The component according to claim 1, comprising a first locking portion (56) for preventing the root from leaving the recess (10), the first locking portion (56) comprising the stop (70).

7. The component according to claim 1, wherein, The rod (38) includes an end portion configured to engage with a tool and be rotatably driven by the tool.

8. The component according to claim 7, wherein, The end is provided with a spline.

9. The component of claim 1, further comprising an anti-rotation device configured to prevent the rod (38) from rotating relative to the fastener (9).

10. The component of claim 9, wherein, The anti-rotation device includes a second locking part (58) to prevent the root from dislodging from the recess (10).

11. The component of claim 10, wherein, The rod (38) includes an end portion configured to engage with a tool and be rotatably driven by the tool, wherein the anti-rotation device further includes: ●The end of the rod (38), • A detachable seat (64) configured to engage with the end rather than with the tool, and the detachable seat is also used to engage with the second locking part.

12. The component according to claim 1, wherein: The clamping device (32) includes a second clamping element (36) configured to be supported in the recess (10) on both the root and the fastener (9). A second clamping force is applied to the root, the second clamping element defining the second threaded hole. ● The rod (38) includes a second thread that connects to the second threaded hole, such that rotation of the rod (38) relative to the second clamping element causes a change in the second clamping force, wherein the change in the clamping force has the same sign as the change in the second clamping force.

13. The component of claim 12, wherein, ●The clamping element (34) and the second clamping element (36) are configured to displace relative to the fastener (9) when the rod (38) rotates relative to the fastener (9). ● The displacement of the clamping element (34) and the second clamping element (36) relative to the fastener (9) causes changes in the clamping force and the second clamping force.

14. The component of claim 12, wherein, The clamping element (34) and the second clamping element (36) are configured to move away from each other or toward each other as the rod (38) rotates relative to the fastener (9) about the axis of rotation.

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