Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B37/00—Nuts or like thread-engaging members
  • F16B37/14—Cap nuts; Nut caps or bolt caps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B39/00—Locking of screws, bolts or nuts
  • F16B39/02—Locking of screws, bolts or nuts in which the locking takes place after screwing down
  • F16B39/08—Locking of screws, bolts or nuts in which the locking takes place after screwing down with a cap interacting with the nut, connected to the bolt by a pin or cotter pin

Definitions

• the invention belongs to the field of mechanical fasteners.
• the invention belongs to the field of positive locking mechanical fasteners.
• a problem raised by the method of fastening a structural assembly by threaded fasteners is that of loosening in use, generally consequence of vibration. Positive locking devices are implemented to solve this problem.
• European Patent Application EP 2 044 342 discloses a positive locking fastening system comprising a screw, a nut, a locking member with a threaded projection and a coupling member.
• the screw includes an external thread and a through cavity including a thread adapted to receive the threaded projection of the locking member.
• the profile of the locking member and the nut are such that it is not always possible to put the coupling member in place without adjusting the tightening of the locking member, in order to align the external profiles of the locking member and the nut.
• a disadvantage of this system is that such an adjustment in fact leads to an excessive or insufficient clamping of the locking member, with the risk of causing, for example, deformations of the fastener or resulting in use of a looser control of fixation.
• the assembly of the fastener is therefore not always possible optimally regardless of the position of the nut after implementation on the screw and usually requires an adjustment operation of the tightening of the nut.
• Japanese Patent Application JP 3629486 discloses a positive locking fastener comprising a screw, a nut and a cap.
• the cap comprises a lower portion with a star-shaped polygonal section having M vertices adapted to engage the nut, and an upper portion adapted to engage an engagement portion of the star-shaped polygonal section screw having N vertices.
• An angular clearance provided between the lower part and the nut and an angular clearance provided between the upper part and the screw engaging part allow to engage the cap on the screw and the nut for a number of positions of the cap given by the largest common divisor of M and N.
• the sum of the angular sets is given by a ratio between 180 ° and the least common multiple of M and N.
• this attachment is particularly suitable for screw / nut assemblies to obtain a larger common divider as small as possible.
• a disadvantage of this invention is therefore that the cap can engage both the screw and the nut at the first test in a limited number of positions, depending on the values of M and N. It is therefore necessary to remove the cap and plastically deform and then re-engage the screw and nut.
• the number of positions of the cap allowing its engagement on the binding must be limited otherwise there is the possibility of loosening the fastener.
• Another disadvantage of the attachment described is that it can be used a limited number of times, about two or three, because of the crimping of the cap in the throat of the nut, and the disassembly by a pull-hub which necessarily damages the cap.
• the invention proposes to solve the problems of the prior art.
• the invention relates to a positive locking device intended to limit the loosening of a nut installed on a screw, said screw extending along a longitudinal axis, said nut having an angular period clamping portion ⁇ , said locking device comprising a first cap and a second cap.
• the first cap having a main axis substantially coincident with the longitudinal axis when the device is in place, comprises:
• centering and rotational immobilization means for cooperating with a free end of the screw
• locking means in axial translation intended to cooperate with a thread of the screw, and a cylindrical outer surface of direction parallel to the longitudinal axis;
• the second cap having a main axis substantially coincident with the longitudinal axis when the device is in place, is adapted to cooperate with the nut and meshing with the first cap, and in that said second cap comprises: a locking portion at a first end, an inner surface of said locking portion having in a plane perpendicular to the main axis of said second cap an internal angular period profile ⁇ / k, where k is a non-zero natural integer, around the main axis of said body, dimensions of the profile being adapted to allow the establishment of the locking portion on the clamping portion of the nut, and, when said clamping portion is introduced into said locking portion, allow a relative rotational movement of said nut relative to said locking portion, about the longitudinal axis, of 9 / 2k angular amplitude;
• a locking portion at a second end having a set of openings passing through said locking portion and intended to receive a pin;
• blocking and locking portions being integral and fixed together
• an inner surface of the locking portion of the second cap and the outer surface of the first cap being adapted to mesh with each other at an angular pitch of 9 / 2k.
• the outer surface of the first cap has at least one tab
• the inner surface of the locking portion of the second cap has a set of flutes, adapted to receive the at least one tab of the first cap.
• the inner surface of the locking portion of the second cap has at least one tab
• the outer surface of the first cap has a set of grooves adapted to receive the at least one tab
• the outer surface of the first cap and the inner surface of the locking portion both have a set of grooves, separated by an angular pitch 9 / 2k.
• k is 1. In one embodiment,
• the first cap comprises a plate substantially perpendicular to the main axis of said first cap
• the centering and immobilizing means of the first cap comprise a central pillar of substantially cylindrical shape with non-circular section, said central pillar extending from a central zone of the lower face of the plate in the direction given by the main axis; the first cap;
• the locking means in axial translation of said first cap comprise at least one foot extending in a direction of the main axis from the lower face of the plate, said at least one foot comprising a claw extending in a substantially perpendicular plane to the main axis from the at least one foot to said central pillar, said at least one foot being made of an elastic material to allow the nesting of the at least one foot in a thread of the screw.
• the first cap has four legs.
• the central pillar has a cylindrical shape with a polygonal section.
• the openings are notches. In one embodiment, the openings are oblong holes.
• the invention also relates to a positive locking fastener comprising:
• a screw having a longitudinal axis and having at one end a head and at a second free end a threaded portion having a cavity opening on said second free end of the screw; a nut intended to be placed on the screw, said nut comprising a clamping portion whose outer surface defines in a plane perpendicular to the longitudinal axis an angular period profile ⁇ ;
• a pin for insertion into the openings of the second cap so as to maintain between them the first cap and the second cap.
• an interior surface of the cavity forms a complementary impression of the central pillar so that said central pillar is adapted to be inserted into said cavity;
• the claws of the first cap are nested in the thread of the screw.
• the nut defines a starry profile with twelve vertices of angular period 30 °;
• the outer surface of the first cap consists of twenty-four tabs separated by an angular pitch of 15 °.
• the invention also relates to a method for implementing a fastener according to the invention.
• the method according to the invention comprises the following steps:
• FIG. 1a represents an isometric view of a positive locking fastening according to the invention, maintaining a structural assembly, in an exemplary embodiment of the invention.
• Figure 1b shows an isometric view with section along the plane (OYZ) of the locking device in the embodiment of Figure 1a.
• FIG. 2 shows a sectional view of the fastener according to the invention in a horizontal plane intersecting the clamping portion of the nut, in the embodiment of Figure 1 A.
• FIG. 3 represents an isometric view of the first cap according to the invention.
• FIG. 4 represents an isometric view of the second cap according to the invention.
• Figures 5a and 5b show two views in section of the fastener according to the invention in a horizontal plane intersecting the clamping portion of the nut and the locking portion of the second cap, in two different configurations.
• Figure 6a shows two sectional views of the fastener according to the invention in a horizontal plane intersecting the locking portion of the second cap.
• Figure 6b shows two sectional views of the fastener according to the invention in a horizontal plane intersecting the locking portion of the second cap.
• FIG. 4 represents an isometric view of the second cap according to the invention, in one embodiment in which the openings are notches.
• a “vertical” direction is given by the direction of the axis (OZ). Any axis of the plane (OXY) thus has a “horizontal” direction.
• a positive locking fastening according to the invention comprises:
• a fastener comprising a screw 1 and a nut 2, maintains fixed between them two structural elements forming a structural assembly 6;
• the screw 1 extends along a longitudinal axis ⁇ and has at one end a head 10 and at a second end a threaded portion January 1.
• the threaded portion January 1 has a cavity 1 10 extending axially and opening on the second end.
• the nut 2 When the screw 1 is installed, the nut 2 is screwed onto the threaded portion 1 1 of said screw with application of a nominal torque, so that the structural elements of the structural assembly 6 are held together by the nut 2 and the screw 1 with the desired pretensioning force.
• the nut 2 comprises a base 20, in contact with the structural assembly 6, and a clamping portion 21 allowing the application of the tightening torque, for example by means of a tool comprising a socket of complementary shape to said portion Clamping.
• the clamping portion 21 of a twelve-sided nut has an outer face defining, in a horizontal plane, a star-shaped profile P with twelve vertices, shown in thick solid lines in the figure. , said profile thus having an angular period ⁇ of 30 ° about an axis substantially coincident with the longitudinal axis ⁇ when the nut 2 is put in place.
• the first cap 3 after placing the nut 2 on the screw 1, the first cap 3 according to the invention is installed, a periphery of the first cap 3 being adapted to cover at least partially the threaded portion 1 1 of the screw 1 and to be fitted into a thread of said threaded portion.
• the first cap 3 has a circular plate 30 and a set of four identical feet 31, regularly disposed on a periphery of said plate.
• the feet 31 extend from a lower face of the plate 30 in a direction given by a main axis of the first cap 3, which main axis is substantially coincident with the longitudinal axis ⁇ when the first cap 3 is installed.
• each of the feet 31 is an extension of a peripheral outer surface of the plate 30 to form a peripheral surface 33 of the first cap 3, which peripheral surface has a set of grooves oriented along the principal axis of the first cap 3.
• the feet 31 do not constitute an extension of the peripheral outer surface of the plate, and the peripheral surface 33 corresponds to said peripheral outer surface of the plate.
• the number of grooves is equal to 24, so that a groove is observed in angular pitch of 15 ° around the main axis of the first cap 3, said angular pitch being equal to the half of the angular period ⁇ of the profile P of the clamping portion 21.
• the feet 31 also have a claw 310 extending radially from a lower end of an inner surface 31 1 of said feet 31 towards the main axis of the cap 3.
• a distance from the inner surface 31 1 of a foot 31 to the main axis of the first cap 3 is substantially equal to a maximum diameter of the threaded portion 1 1 of the screw 1 so that the claw 310 of each of the feet 31 is adapted to be fitted into the thread of the threaded portion 1 1.
• the feet 31 are made of an elastic material so as to allow the interlocking and disengagement of said claws without damaging the first cap 3.
• the elastic properties of the material constituting the feet 31 takes into account in particular the helical shape of the thread of the threaded portion 1 1 involving differentiated interlocking from one foot to the other and therefore different constraints.
• the first cap 3 also comprises a central pillar 32 of substantially cylindrical shape of hexagonal section extending from a central zone of the lower face of the plate 30 in the direction given by the main axis of the first cap 3.
• the central pillar 32a a shape complementary to that of the cavity 1 10, so that the central pillar 32 can be inserted without substantial play in said cavity.
• the cavity 1 10 and the central pillar 32 have shapes adapted to make it impossible to rotate the first cap 3 with respect to the screw 1. By “make it impossible to rotate”, it must be understood without damage to the first cap 3 and within the limits of clearances necessary or unavoidable to allow the mounting of said first cap taking into account manufacturing tolerances of said first cap and the screw 1.
• the central pillar 32 and the cavity 1 10 may have other forms adapted to make it impossible to rotate the first cap 3 around the screw 1, in particular they may have a cylindrical shape with a polygonal section or a non-circular elliptical shape.
• the central pillar 32 When the first cap 3 is placed on the screw 1, the central pillar 32 is inserted into the cavity 1 10 and a solid portion of the threaded portion 1 1 surrounding said cavity is inserted between said central pillar and the feet 31, the claw 310 of each of said feet fitting into a thread of said threaded portion.
• the second cap 4 is installed over said first cap and the nut 2.
• the second cap 4 has a body 40 having a locking portion 401 and a locking portion 402.
• the body 40 has an inner surface adapted to allow the locking portion 401 to cooperate with the nut. 2 and the locking portion 402 to cooperate with the first cap 3.
• An inner surface of the locking portion 401 has in a plane perpendicular to a main axis of the body 40 substantially coincident with the longitudinal axis ⁇ when the second cap 4 is put in place, a profile P 'crenellated angular period ⁇ around the main axis of said body.
• the dimensions of the profile P and the profile P ' are adapted to allow the insertion of the clamping portion 21 in the locking portion 401, and, when said clamping portion is introduced into said locking portion, allow a rotational movement said relative nut of said nut relative to said locking portion, about the longitudinal axis ⁇ , of angular amplitude ⁇ equal to half the angular period ⁇ , ie 15 °, as illustrated in Figures 5a and 5b.
• FIG. 5a shows the assembly of clamping portion 21 and blocking portion 401 in a first configuration in which peaks internal 210, 4010 profiles P and P 'coincide, that is to say two coinciding inner vertices 210, 4010 form a line perpendicular to the longitudinal axis ⁇ .
• FIG. 5b shows the same assembly in a second configuration corresponding to the first configuration in which the clamping portion 21 or the locking portion 401 has undergone a rotation of 7.5 °, ie a half angular amplitude ⁇ .
• An inner surface of the locking portion 402 of the body 40 has grooves oriented along the main axis of the second cap 4, so that the inner surface of said locking portion is able to mesh with the peripheral surface 33 of the first cap 3.
• an average diameter of the first cap 3 is smaller than an average diameter of the second cap 4.
• the number of grooves of the inner surface of the locking portion 402 is equal in the example shown in the number of grooves present on the peripheral surface 33 of the first cap 3, and each groove of the inner surface is spaced apart from the adjacent grooves by an angular pitch of 15 ° about the main axis of the second cap 4.
• the role of these splines being to block the rotation between the first cap 3 and the second cap 4, it is not necessary in practice to have as many grooves on the peripheral surface 33 as on the inner surface of the locking portion 402.
• the peripheral surface 33 has a number of grooves less than the number of grooves of the inner surface of the locking portion 402, spaced at a multiple angle of the angular pitch of 15 °, by example three grooves spaced 30 °.
• the flutes of the peripheral surface 33 are replaced by a single tab.
• the term "tongue” means a protruding strip forming a tenon on the peripheral surface 33 intended to enter, for assembly, into a groove close to the inner surface of the locking portion 402.
• the locking portion 402 which has a number of grooves less than the number of grooves of the peripheral surface (or a single tongue), according to the same principle.
• the locking portion 402 also has two pairs of openings 4020 passing through said locking portion.
• the dimensions of the holes 4020 are adapted to receive a pin 5, the role of said pin being to lock axially between them and on the screw 1 the first cap 3 and the second cap 4.
• the openings may be holes or notches as illustrated respectively in Figures 4 and 7.
• the first cap 3 is then put in place at the second end of the screw 1.
• the central pillar 32 is inserted into the cavity 1 10 of the threaded portion 1 1 and the claws 310 of the feet 31 are fitted into the thread of the threaded portion 1 1, these interlockings being made possible by an elastic nature of said feet.
• the interlocking of these claws 310 in the thread thus makes it possible to block the translation of the first cap 3 along the main axis of said first cap, substantially coinciding with the longitudinal axis ⁇ of the screw 1.
• the number of feet is not critical for the implementation of the invention, insofar as a single foot makes it possible to block said translation of the first cap 3.
• at least two feet diametrically opposites are implemented to ensure a good performance of the first cap 3.
• the second cap 4 is then put in place.
• the second cap 4 is arranged so that the grooves of the inner surface of the locking portion 402 mesh with the grooves of the peripheral surface 33 of the first cap 3, thereby forming a set of links slides allowing the translation of said second cap along the main axis of said second cap then substantially coincides with the longitudinal axis ⁇ , while blocking the rotation between the two caps 3, 4.
• the splines or, where appropriate, the tongue
• the splines extend only over a portion of said surfaces.
• the second cap 4 is removed by axial translation along the longitudinal axis ⁇ , then is rotated about said longitudinal axis, in a direct or indirect direction, an angle equal to ⁇ .
• the second cap 4 is then replaced in axial translation along the longitudinal axis ⁇ .
• the second cap 4 can necessarily be put in place on the tightening portion 21 of the nut 2.
• the pin 5 is inserted into the openings 4020 of said second cap.
• the pin 5 implemented in the illustrated example is a jumper pin.
• the arrangement of the openings 4020 is adapted to allow insertion of the pin 5 between the feet 31 and the nut 2, advantageously in contact with the feet 31.
• the pin 5 thus makes it possible to block an axial translation of the second cap 4 with respect to the first cap 3, and therefore with respect to the screw 1.
• An advantage of the invention is that it allows a positive locking of the attachment regardless of the nominal tightening of the nut 2 during installation by allowing in all cases the establishment of the device. With reference to FIGS. 6a and 6b, there are gaps between the elements of the binding according to the invention.
• FIG. 6a illustrates the maximum angular clearance existing between the nut 2 and the second cap 4 in the case of loosening of said nut.
• the left view and the right view illustrate the relative positions of the clamping portion 21 vis-à-vis the locking portion 401 respectively before and after loosening of the nut in the most pessimistic scenario of loosening said nut.
• FIG. 6b illustrates the maximum clearance existing between the screw 1 and the first cap 3.
• the left view and the right view illustrate the relative positions of the threaded portion 1 1 and the central pillar 32 respectively before and after loosening the screw 1 in the most pessimistic scenario of loosening said screw.
• the attachment according to the invention has a maximum loosening of about 22 ° due to the existence of these games, including the angular amplitude ⁇ of 15 ° as shown in Figure 6a.
• This maximum loosening corresponds to a maximum prestressing loss of approximately 7.5%.
• Maximum loss of prestressing is understood to mean the loss of prestressing in the most pessimistic scenario of loosening of the fastening, taking into account the maximum possible rotation according to the principles exposed plus the play catch-ups.
• the invention is not limited to the embodiment shown, and can be applied in particular to other nuts. It should be noted, however, that the use of a different nut changes the maximum prestressing loss.
• the adaptation of the invention to a hexagon nut as described above leads to a maximum loosening greater than 30 °, since the angular displacement of the nut 2 in the second cap 4 is then 30 °. This leads to a maximum loss of prestress greater than 10%.
• one solution is to keep the profile P 'of the blocking portion 401 of the second cap 4 determined in the case of a 12-point nut, so that the deflection
• the angle of the nut in the second cap is 15 ° instead of 30 °. It may then be necessary, during the installation of the second cap (4), to repeat several times the step of removing, rotating, and replacing the cap to find the position of said second cap allowing its engagement on the nut .

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Dowels (AREA)
• Connection Of Plates (AREA)
• Bolts, Nuts, And Washers (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=59746107

Family Applications (1)

Country Status (6)

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• 2017
  • 2017-06-15 FR FR1755417A patent/FR3067768B1/fr active Active
• 2018
  • 2018-06-14 CN CN201880053456.0A patent/CN111316006B/zh active Active
  • 2018-06-14 US US16/622,932 patent/US11353054B2/en active Active
  • 2018-06-14 EP EP18749436.4A patent/EP3638911A1/fr not_active Withdrawn
  • 2018-06-14 WO PCT/FR2018/051416 patent/WO2018229445A1/fr unknown
  • 2018-06-14 CA CA3066174A patent/CA3066174A1/fr active Pending

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