Assembly for fixing a nut onto a screw and associated method

Abstract

An assembly (3) for fastening a nut (2) to a screw (1) comprising a screw (1), a threaded nut (2), and a locking member (4) configured to prevent rotation of said nut (2) about the longitudinal axis (X) on the screw (1) in a locking position, the locking member (4) comprising a body (40) configured to be inserted along a locking axis (X4) successively into a locking passage (22) of the nut (2) and into a through opening (13) of the screw (1) to obtain a locked locking position (LTO), said locking member (4) comprising two arms (41) being elastically deformable so as to deform by contact with the notches (21) when the body (40) is inserted into the through opening (13) of the screw (1) along the locking axis (X4). Figure 4

Description

Title of the invention: Assembly for fixing a nut onto a screw and associated method. Technical field

[0001] The present invention relates to the field of mechanical fasteners. In particular, the invention relates to a fastening assembly for a nut on a screw.

[0002] It is known to connect two mechanical parts by bolting, that is, by screwing a nut onto a bolt. Due to vibration conditions, it is sometimes necessary to lock the position of the nut on the bolt to prevent accidental loosening.

[0003] For this purpose, with reference to [Fig. 1], a prior art fixing assembly 100 is known comprising a fixing screw 110, a nut 120 and a pin 130.

[0004] The fixing screw 110 extends longitudinally along a screw axis XI1 between a head 111 and a foot. The fixing screw 110 has a threaded portion 112 at its foot onto which the nut 120 can be screwed. The fixing screw 110 has a through opening 113, extending along a locking axis X12 (see Figures 2 and 3) extending orthogonally to the screw axis XI1.

[0005] The nut 120 has a threaded opening configured to cooperate with the threaded portion 112 of the fastening screw 110. The nut 120 further has projecting features 121, for example slots, between which the pin 130 can be inserted. Such a fastening assembly 100 according to the prior art is known to those skilled in the art.

[0006] When fastening two mechanical parts, the fastening screw 110 extends into openings in the mechanical parts, and then the nut 120 is screwed onto the threaded portion 112 of the fastening screw 110 to achieve tightening. Next, with reference to [Fig. 2], an operator inserts the pin 130 successively between two protruding elements 121 of the nut 121, into the through opening 113 of the fastening screw 110, and between two protruding elements 121 of the nut 120. Thus, the nut 120 is locked in position and can no longer rotate around the fastening screw 110.

[0007] To prevent accidental removal of the pin 130 and with reference to [Fig. 3], the pin 130 is manually deformed by an operator to prevent its removal by translation along the locking axis X12. In addition, to avoid the risk of injury or snagging, the length of the pin 130 can be reduced after insertion by cutting or similar means.

[0008] Such a fastening assembly has many disadvantages,

[0009] The operations of deforming and cutting the pin are time-consuming, which is problematic in the aeronautical field which imposes production rates Manufacturing costs are constantly increasing. Furthermore, these operations are carried out in cramped working environments, which can increase the physical strain on operators. The cutting process itself can also lead to injuries.

[0010] In addition, the cut portions of the pins must be recovered following the cutting step, which increases the time required to set up a fastener and increases the risk of loss of a cut portion. PRESENTATION OF THE INVENTION

[0011] The invention relates to a nut-on-screw fastening assembly, said assembly comprising: • a screw extending along a longitudinal axis and having a threaded end portion with a through opening extending along a locking axis; • a threaded nut configured to cooperate by screwing with the end portion of the screw and comprising at least two notches, each notch extending in projection along the longitudinal axis, the two notches delimiting between them at least one locking passage configured to be aligned with the through opening of the screw when the nut is on the screw in a locking position; • a locking member configured to prevent rotation of said nut around the longitudinal axis on the screw in the locking position, the locking member comprising a body configured to be inserted along a locking axis successively into the locking passage of the nut and into the through opening of the screw to obtain a locked locking position,

[0012] The assembly is remarkable in that said locking member comprises two arms extending on either side of the body, the arms being elastically deformable so as to deform by contact with the notches when the body is inserted into the through opening of the screw along the locking axis, in the locked securing position, the two arms being configured to come into contact with the nut in the event of withdrawal of the body along the locking axis.

[0013] To allow the nut to be securely fastened to the screw, i.e., to obtain the locked locking position, the locking member is inserted into the through-hole of the screw. In particular, the body of the locking member prevents the nut from rotating around the screw, since the body extends within a locking passage. The arms of the locking member, for their part, hold the body within the through-hole of the screw, i.e., prevent the body from moving within the opening and thus prevent the member from being withdrawn from the opening. through. The locking mechanism therefore allows for a simple, quick and compact fixing of the nut onto the screw.

[0014] According to one aspect, the arms are symmetrical with respect to the body.

[0015] According to one aspect, the arms are configured to present a first gap in a resting state and a second separation in an insertion state, the second separation being greater than the first separation.

[0016] Thus, the arms spread apart elastically to bypass the nut and make it captive to prevent any movement.

[0017] According to one aspect, the second gap is greater than the diameter of the nut.

[0018] According to one aspect, each arm of the locking member is globally arched by so as to fit the periphery of the nut.

[0019] According to one aspect, the nut having a hexagonal cross-section defining faces, each arm comprises at least two segments to fit two faces of the nut. Thus, any movement is avoided, particularly due to vibrations. The service life is therefore extended.

[0020] According to one aspect, each arm has at least one end segment extending in the opposite direction to the nut. The end segments facilitate insertion by forming a flared, funnel-like guiding surface to guide the arms around the nut. Such an end segment allows the operator to intentionally remove the locking member, in particular by applying force to the free end of the locking member body.

[0021] In one aspect, the nut comprises at least four notches, each notch projecting along the longitudinal axis, the four notches respectively defining at least one locking passage, and in which each arm has a stop, the stop of each arm being configured to cooperate with a locking passage of the nut in the locked position. Preferably, the nut has six notches and is hexagonal in shape.

[0022] Such a stop ensures a locking mechanism by interlocking, which is robust over time. The elasticity of the arms further improves this interlocking.

[0023] The invention also relates to a method for assembling the fastening assembly as described above, comprising steps consisting of: • Screw the nut onto the end portion of the screw until the through opening of the screw is aligned with the locking passage between the notches of said nut, the nut then being on the screw in the locking position, • Insert the body of the locking member along the locking axis successively into the locking passage of the nut and into the through opening of the screw, the arms deforming elastically to extend around said nut, to obtain the locked securing position.

[0024] According to one aspect, the nut comprises at least four notches, each notch projecting along the longitudinal axis, the four notches respectively delimiting between them at least one locking passage and in which each arm has a stop, said method further comprising the following step: • translate the body of the locking member along the locking axis in the through opening of the screw, until each stop of each arm enters a locking passage of the nut. PRESENTATION OF THE FIGURES

[0025] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0026] Fig. 1 is a schematic representation of an exploded view of a prior art fastener assembly comprising a fixing screw, a nut and a pin.

[0027] Fig. 2 is a schematic cross-sectional representation of the fixing screw of Fig. 1, making visible the pin inserted into the through opening of the fixing screw.

[0028] Fig. 3 is a schematic representation similar to Fig. 2, in which the pin has been manually deformed by an operator.

[0029] Fig. 4 is a schematic representation of a fastening assembly according to the invention, comprising a nut, a screw and a locking member.

[0030] Fig. 5 is a schematic front view representation of a first embodiment of a locking member in a rest state.

[0031] Fig. 6 is a schematic representation of the locking member in an insertion state.

[0032] Fig. 7 is a schematic representation of the locking member after insertion.

[0033] Fig. 8 is a schematic representation of the locking mechanism during an attempted accidental removal.

[0034] Fig. 9 is a schematic front view representation of a second embodiment of a locking member in a rest state.

[0035] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0036] The invention relates to a fixing assembly of a nut 2 on a screw 1. With reference to [Fig.4], the assembly 3 comprises a screw 1, a nut 2 and a locking member 4.

[0037] The screw 1 according to the invention is similar to the prior art screw shown in Figures 1 to 3. In particular, the screw 1 extends longitudinally along a longitudinal axis XI between a screw head 10 and a threaded end portion 12. The screw 1 has a screw body 11 projecting from the screw head 10 along the longitudinal axis XI to the end portion 12. The screw 1 has a through opening 13 formed in the end portion 12.

[0038] The nut 2 is also similar to the prior art nut shown in Figures 1 to 3. In particular, the nut 2 is threaded and extends along the longitudinal axis XL. It is configured to cooperate by screwing with the end portion 12 of the screw 1. With reference to [Fig. 4], the nut 2 comprises at least two notches 21; here, the nut 2 has six notches 21. Each notch 21 projects from the longitudinal axis XI, and two notches 21 define at least one locking passage 22; here, the six notches 21 define six locking passages 22. The nut 2 has a generally hexagonal cross-section.

[0039] At least one locking passage 22 is configured to be aligned with the through opening 13 of the screw 1, when the nut 2 is in a locking position on the screw 1, i.e. when the nut 2 is screwed into the end portion 12 of the screw 1. In the example shown in [Fig.4], two of the locking passages 22 facing each other are configured to be aligned with the through opening 13 of the screw 1, when the nut 2 is in a locking position on the screw 1, i.e. when the nut 2 is screwed into the end portion 12 of the screw 1.

[0040] As will be shown later, a new locking member 4 can be used in place of a locking member according to the prior art.

[0041] With further reference to [Fig. 4], the locking member 4 is configured to prevent the nut 2 from rotating about the longitudinal axis XI on the screw 1 in the locking position. In other words, the locking member 4 is configured to prevent the nut 2 from unscrewing the screw 1 and thus to keep the nut 2 on the screw 1 in the locking position. In particular, and with reference to [Fig. 5], the locking member 4 comprises a body 40 configured to be inserted along a locking axis X4, transverse to the longitudinal axis XI, successively into the locking passage 22 of the nut 2 and into the through opening 13 of the screw 1, to obtain the locked locking position PSV illustrated in [Fig. 4].

[0042] The locking member 4 is notable in that it comprises two arms 41 extending on either side of the body 40. The arms 41 are elastically deformable so as to deform by contact with the notches 21 when the body 40 is inserted into the through opening 13 of the screw 1 along the locking axis. In this example, with reference to [Fig. 5], the body 40 extends along the locking axis X4 and comprises a front end 40a, preferably beveled to facilitate its insertion, and a rear end 40b connected to a base 42 which extends orthogonally to the body 40. The arms 41 are fixed to the base 42 to form together a U-shaped piece.

[0043] The length of the body 40 of the locking member 4 is greater than the diameter of said end portion 12 of the screw 1. Preferably, the locking member 4 is offered in different sizes to suit different needs.

[0044] Advantageously, the two arms 41 are symmetrical to each other with respect to the body 40 which extends along the locking axis X4.

[0045] With reference to Figures 5 and 6, the arms 41 are configured to have a first gap DI in a rest state E1, i.e., without stress, and a second gap D2 in an insertion state E2, in the presence of mechanical stress. The second gap D2 is greater than the first gap DI so as to circumvent the circumference of the nut 2, as will be shown later. Preferably, the second gap D2 is greater than the diameter of the nut 2.

[0046] The first gap DI corresponds to the distance between the arms 41 when they are in their initial position, which is an unconstrained position ([Fig. 5]). In other words, the first gap DI corresponds to the distance between the arms 41 when no force is applied to them. This is the rest position of the arms 4L. The second gap D2 corresponds to the distance between the arms 41 when they deform elastically during the insertion of the body 40 into the through opening 13 of the screw 1 along the locking axis X4 ([Fig. 6]). In other words, the second gap D2 corresponds to the distance between the arms 41 when a force is applied to them, in particular when a force pushes the arms 41 in a direction opposite to the body 40 (here, the reciprocal force applied by the nut 2). This is the distance between the arms 41 when they are elastically deformed.After insertion, in the locked securing position PSV, the arms 41 are preferably separated from the first gap DI as illustrated in [Fig.7].

[0047] As illustrated in [Fig. 5], the arms 41 of the locking member 4 are generally curved to allow passage of the nut 2, adapting to the shape of the nut 2 while minimizing the overall size. In this example, each arm comprises two segments 41a, 41b (a first segment 41a and a second segment 41b) to fit two faces of the nut 2. Such segments 41a, 41b are particularly well-suited for a nut 2 with a hexagonal cross-section defining six faces. Such an arm 41 advantageously prevents any withdrawal of the locking member 4, as will be shown later.

[0048] In this example, again with reference to [Fig. 5], each arm 41 has at least one end segment 41c extending in the opposite direction to the nut 2. The end segments 41c facilitate insertion by forming a flared, funnel-like guiding surface to guide the arms 41 around the nut 2. Such an end segment 41c makes it easier for an operator to grip the arms 41 when removing the locking member 4. The end segments 41c form a raised area and facilitate gripping and moving an arm 41 away from the nut 2.

[0049] Still with reference to [Fig.5], each arm 41 has a stop 410, preferably formed at the interface between the second segment 41b and the end segment 41c.

[0050] Each stop 410 is configured to fit into a locking passage 22 when the nut 2 is in a locked securing position on the screw 1. In particular, with reference to [Fig. 4], the nut 2 has six notches 21 extending in projection along the longitudinal axis XL. The six notches 21 delimit at least one locking passage 22 between themselves. In the locked securing position of the nut 2 on the screw 1, each stop 410 fits into a locking passage 22 of the nut 2, so as to hold the locking member 4 on the nut 2 and thus prevent the body 40 of the locking member from translating into the through opening 13 of the screw 1, and therefore allows it to be held in position in the through opening 13.

[0051] According to a first embodiment shown in [Fig. 5], the locking member 4 is entirely metallic. In particular, the body 40 of the locking member 4 is welded to the U-shaped piece comprising the base 42 and the arms 4L. In such an embodiment, the manufacture of the locking member 4 is simple and quick, making it possible to maintain high production rates.

[0052] According to a second embodiment shown in [Fig. 9], the body 40 of the locking member 4 is metallic and the U-shaped piece, comprising the base 42 and the arms 41, is made of thermoplastic material. In this embodiment, the U-shaped piece is a single piece. An opening is formed in the base 42 to allow the passage of the body 40, which has at its free end a stop 43 that makes flat contact with the base 42 and secures the arms 41 to the body 40. Advantageously, the opening in the base 42 is tightly fitted to the body 40 to prevent the U-shaped piece from moving relative to the body 40. In this embodiment, the arms 41 have greater flexibility, which allows for faster positioning of the arms 41, and therefore of the locking member 4, around the nut 2.

[0053] In the locked position PSV shown in [Fig. 4], the two arms 41 of the locking member 4 are configured to contact the nut 2 if the locking member is withdrawn along the locking axis X4. In other words, the two arms 41 of the locking member 4 are configured to contact the notches 21 of the nut 2 at contact zones ZC if the body 40 of the locking member 4 is translated along the locking axis X4 as illustrated in [Fig. 8]. Any withdrawal along the locking axis X4 is prohibited, as is any rotation about the longitudinal axis XI. The locking member 4 is thus held securely in position on the nut 2 and on the screw 1, preventing it from falling.

[0054] The invention also relates to a method for assembling the assembly 1 described above. The method comprises at least the steps of: • screw nut 2 onto the end portion 10 of screw 1 until the through opening 13 of screw 1 is aligned with the locking passage 22 between the notches 21 of said nut 2, nut 2 then being in the securing position on screw 1; • Insert the body 40 of the locking member 4 along a locking axis successively into the locking passage 22 of the nut 2 and into the through opening 13 of the screw 1, until the arms 41 extend around said nut 2, to obtain a locked securing position.

[0055] Advantageously, the method further comprises the step of translating the body 40 of the locking member 4 along the locking axis X4 in the through opening 13 of the screw 1, until each stop 410 of each arm 41 is inserted into a locking passage 22 of the nut 2. As illustrated in Figures 5 and 6, the spacing between the arms 41 increases between the rest position E1 and the insertion position E2 in order to bypass the nut 2.

[0056] As illustrated in [Fig.7], in the locked securing position PSV, the arms 41 externally surround the nut 2 and the segments 41a, 41b cooperate intimately with the faces of the nut 2 to prevent any movement.

[0057] In the event of accidental force or under the effect of vibrations, the locking member 4 cannot be removed along the locking axis X4 because the arms 41 come into contact with the nut 2 according to contact areas ZC as illustrated in [Fig.8], which ensures a reliable locking.

[0058] The fastening assembly 3 according to the invention allows for a secure fastening of the nut 2 onto the screw 1 in a quick manner, making it possible to meet the high production rates of the aeronautical field, without increasing the strain on operators and reducing the risk of injury.

Claims

Demands

1. Assembly (3) for fastening a nut (2) to a screw (1), said assembly (3) comprising: • a screw (1) extending along a longitudinal axis (XI) and having a threaded end portion (12) having a through opening (13) extending along a locking axis (X4); • a nut (2) tapped and configured to cooperate by screwing with the end portion (12) of the screw (1) and comprising at least two notches (21), each notch (21) projecting along the longitudinal axis (X), the two notches (21) defining between them at least one locking passage (22) configured to be aligned with the through opening (13) of the screw (1) when the nut (2) is on the screw (3) in a locking position; • a locking device (4) configured to prevent rotation of said nut (2) around the longitudinal axis (X) on the screw (1) in the locking position,The locking member (4) comprising a body (40) configured to be inserted along a locking axis (X4) successively into the locking passage (22) of the nut (2) and into the through opening (13) of the screw (1) to obtain a locked locking position (PSV), • said assembly (3) being characterized in that: • said locking member (4) comprises two arms (41) extending on either side of the body (40), the arms (41) being elastically deformable so as to deform by contact with the notches (21) when the body (40) is inserted into the through opening (13) of the screw (1) along the locking axis (X4), • in the locked locking position (PSV), the two arms (41) being configured to come into contact with the nut (2) in the event of withdrawal of the body (40) along the locking axis (X4).,

2. Assembly (1) according to claim 1, wherein the arms (41) are symmetrical with respect to the body (40).

3. Assembly (1) according to any one of claims 1 to 2, wherein the arms (41) are configured to have a first gap (D1) in a rest state (E1) and a second gap (D2) in an insertion state (E2), the second gap (D2) being greater than the first gap (D1).

4. Assembly (1) according to claim 3, wherein the second gap (D2) is greater than the diameter of the nut (2).

5. Assembly (1) according to any one of claims 1 to 4, wherein each arm (41) of the locking member (4) is globally arched so as to fit the periphery of the nut (2).

6. Assembly (1) according to any one of claims 1 to 5, wherein, the nut (2) having a hexagonal section defining faces, each arm (41) comprises at least two segments (41a, 41b) to fit two faces of the nut (2).

7. Assembly (1) according to any one of claims 1 to 6, wherein each arm (41) comprises at least one end segment (41c) extending in the opposite direction to the nut (2).

8. Assembly (1) according to any one of claims 1 to 7, wherein the nut (2) comprises at least four notches (21), each notch (21) projecting along the longitudinal axis (X), the four notches (21) delimiting respectively between them at least one locking passage (22) and wherein each arm (41) has a stop (410), the stop (410) of each arm (41) being configured to cooperate with a locking passage (22) of the nut (2) in the locked securing position (PSV).

9. A method for assembling the fastening assembly (1) according to any one of claims 1 to 8, comprising the steps of: • screwing the nut (2) onto the end portion (13) of the screw (3) until the through opening (13) of the screw (1) is aligned with the locking passage (22) between the notches (21) of said nut (2), the nut (2) then being in the locking position on the screw (3), • inserting the body (40) of the locking member (4) along the locking axis (X4) successively into the locking passage (22) of the nut (2) and into the through opening (13) of the screw (3), the arms (41) deforming from

10. elastically to expand around said nut (2), to obtain the locked securing position (PSV). Assembly method according to claim 9, wherein the nut (2) comprises at least four notches (21), each notch (21) projecting along the longitudinal axis (X), the four notches (21) respectively defining at least one locking passage (22) and wherein each arm (41) comprises a stop (410), said method further comprising the following step: • translate the body (40) of the locking member (4) along the locking axis (X4) in the through opening (13) of the screw (3), until each stop (410) of each arm (41) enters a locking passage (22) of the nut (2).

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