FR2525704A1 - ROD FOR A FIXING APPARATUS FOR FLOWING AND SHEARING AND FIXING DEVICE COMPRISING SUCH A ROD - Google Patents

Abstract

THE INVENTION RELATES TO A ROD FOR A CREEP AND SHEAR FIXING DEVICE. SUCH A ROD 20 ESSENTIALLY CONSISTS OF A HEAD 21, A CYLINDRICAL TAIL 22, AND A NECK 24 AT THE LEVEL OF WHICH A PERIPHERAL THROAT 27 IS MADE SUCH AS A THREAD INTENDED TO COOPERATE WITH A COLLAR 40 TO ENSURE THE FIXING OF TWO PIECES 11 AND 12 THE INVENTION IS APPLICABLE IN PARTICULAR TO THE FIELD OF AVIATION.

Description

The present invention relates to a rod intended for

  be used in a creep fixation device and

  Sling and further relates to the fastening device itself in that it comprises such a rod and another fastener. Creep and shear fasteners, which are used very commonly in aerial vehicles, especially to hold together two or more

  such as metal foils, include

  a rod that passes through aligned aligned holes

  in said parts The tail of the rod has a resistance

  sufficient material strength and a cross-section sufficient to withstand shear forces

  which are exerted on the fixing device and for

  These forces are often extremely important The fastening device must also be able to withstand longitudinal tensile forces that result from the bending of the fastening device. For this purpose, the stem comprises a head and a peripheral groove, and a fastener can be applied on the groove, so that the parts can be clamped between the head

  and the fastener These forces are usually considered

  significantly weaker than shear forces.

  So far, it has been common practice to

  Sea head and throat in a conventional configuration, and it follows that the head section and throat section are too strong and too heavy These features lead to a double disadvantage In the first place, the excess weight is particularly undesirable for all flying machines and, secondly, materials such as titanium are so expensive that it is not really

  possible to supply quantities of material not needed.

sary.

  The present invention aims to remedy these drawbacks.

  provided by providing a rod for the aforementioned type of fastener and in which the resistances of the head and the groove are substantially equal and are only sufficient to withstand the longitudinal tensile forces produced by the bending of the fastener. the tail of the stem can be made as important as

  desired, to transfer the applied shear load.

  Consequently, the invention makes it possible to produce a balanced rod

  who has no excess weight and who does not have

no lost material.

  It is another object of the invention to provide a rod which is constructed in such a way that it is optimally resistant to fatigue forces in a critical region located

  near the end of the cylindrical shank.

  According to the invention, a metal rod equi-

  liberate, creep and shear, essentially comprises a head section, a cylindrical tail section, a section

  transition and a reduced collar section, in that order.

  A peripheral groove, such as a thread or a throat

  annular, is formed at the level of the reduced neck section.

  Resistance inherent to the head section and the throat

  peripheral, to withstand the long-term tensile forces

  are substantially equal and only sufficient to withstand such forces that occur under flexure of the device. The inherent strength of the cylindrical tail section to withstand shear forces is sufficient to withstand the forces of

  shear occurring in the fastener.

  According to a preferred but optional feature of the invention, the transition section comprises, with the neck section, an intermediate section which undergoes locally hardening with the tool, so as to withstand the forces

fatigue in this region.

  Other features and benefits of this

  invention will become more apparent from the following description,

  made with reference to the accompanying drawings in which Figure 1 shows a longitudinal sectional view of the preferred embodiment of the invention;

  FIG. 2 represents a right-hand view corresponding to

  in Figure 1; Figure 3 shows an enlarged view of a portion of Figure 1; FIG. 4 represents a longitudinal sectional view

  another embodiment of the invention which is illus-

  partly in the assembled state and partly in the disassembled state; and FIG. 5 is a side elevational view of a fragment of an optional section of the rod shown in FIG.

in Figure 1.

  Referring to FIG. 1, a fixing device

  The creep and shear ratio according to the invention is

  designed to hold together two pieces 11 and 12 which, in the present case, consist of sheets or plates

  metal, for example sheets or plates of an alloy

  This device with rod and fastener can of course hold together other parts

  sheets or plates, for example parts of

mounted on plates.

  Sheets 11 and 12 have through holes

  13 and 14 which are aligned when necessary.

  In an embodiment, an embedded countersink is provided at a first outer face 16 of the sheet 11.

  outer face 17 is shaped on the sheet 12.

  A creep and shear metal rod 20 is mounted in the aligned holes. It is preferable but not necessary to make a press fit fit, i.e. the rod has slightly larger dimensions than the holes. , which determines the prestressing of the walls of the holes and makes the assembly more resistant to fatigue The joints

  are well known and do not require any descrip-

more detailed information.

  The rod 20 comprises the following sections, in the order indicated: a head section 21, a cylindrical tail section 22, a section 24

  Transition with reduction and a section of collar 24.

  The transition section connects the tail section and the collar section It comprises a rounded shoulder 25 which is contiguous to the tail section and a section

  intermediate 26 which is contiguous to the neck section.

  The neck section comprises a peripheral groove 27 In the preferred embodiment of the invention,

  this groove is constituted by a conventional helical thread

  that which is achieved, in particular by rolling, at the level of the collar section.

  This threading stops before reaching the intermediate section 26. The intermediate section 26 undergoes a local hardening tool The preferred technique is to perform a pushing operation at the intermediate section with a tool of the This operation moves the metal on each side so as to form beads 28 and 29 It is important to note that these beads exist only at locations where they do not interfere with any operation. intermediate section causes this region to be much more resistant to fatigue forces than would be the case without this mechanical hardening operation Because this region is at a location where it

  There is a relatively abrupt change of

  fatigue is of considerable importance.

  This feature is however optional.

  The transition section is represented in the form

  a surface of revolution forming a non-perpendicular angle

  to the axis of symmetry 30 of the fastening device A

  As a variant, this section could also be

  ter in the form of a plane normally arranged at this axis.

  The intermediate section would then be located at and near the radius that would exist where the section of

  transition joins the collar stretch.

  Helical thread with a diameter

  of constant top and a constant bottom diameter

  Another type of throat, which is not shown, consists of a groove of the annular type which extends around the neck section in a plane. There may be one or more grooves of this groove. type

  and these may or may not have the same dimensions.

  sions. Also, a helical groove must not always have a constant top diameter and a constant bottom diameter. There are applications for which a top diameter may be provided which increases as it deviates from the top. end corresponding to

  the head The diameter of the bottom can change or not.

  The head section shown in FIG. 1 is made in the form of a head intended to be embedded in a countersink. If the application does not require drowning the head in a countersink, it is possible to make a projecting head. such as the head 35 which is shown in FIG. 5 The term "salient" means that the head is

  protrusion with respect to the first outer face.

  The creep and shear fixation device

  according to the invention is completed by a fastener 40.

  Because this device is studied with great care, to reduce to a minimum value the weight and resistance of the head section and the neck section, it is advantageous to use a fastener that is sensitive to torque.

  so that it can be put in place for a couple

  conque maximum but not for a torque greater than the latter.

  We then obtain a fixing device presenting the

optimal features.

  The preferred fastener that can be used for this purpose is the so-called "Hi-Lok" necklace manufactured by the so-called HiShear Corporation, Torrance, California, United States of America. of United States Patent No. 3,390,906 which is

  incorporated in the present description because it describes

  such a necklace However, for more details about

  this necklace, it is possible to refer to this patent.

  The collar 40 essentially comprises a nut 41, a drive section 42, against which a

  a tool providing a torque for driving said section

  and a section of shear 43 which is intended to

  break when applying a predetermined pair.

  The drive section then falls and leaves the nut tightened on the rod with a correct applied torque and that previously load in the axial direction and so

  correct the fixing device according to the invention.

  6- The nut comprises a counterboring 44 which receives and allows the release of the transition section as well as any part of the tail which could project relative to the second outer face, perhaps following a passing of dimensional tolerances for stacking. The fixing device which is represented in FIGS. 1 to 3 is put in place by the application of a torque, but it is also possible to install the fixing device according to the invention by means of a

  operation of repoussage or repression of the metal.

  For example, with reference to FIG. 4, a rod 50 comprises a head section (not shown) as represented in FIG. 1 or FIG. 5, a tail section 51, a transition section 52 and a section of FIG.

  collar 53 Instead of the normal helical thread that is re-

  shown in FIG. 1, said rod comprises a series of peripheral grooves 54 each of which is located in its

  own respective plane which is normal to the axis of symmetry 55.

  The diameters of the vertices increase as and when

  that the gorges progress towards the pass or the se-

  the end of the stem The bottoms of the gorge can all suitably have the same diameter but

  can also increase if this is preferred.

  Helical threads with increasing crown diameter could also be used instead

gorges represented.

  A collar 60 in the form of a

  ring is intended to be pushed back onto the throats, for example

  This collar is constituted by a ductile metal which is moved by a flared embossing tool 61, the latter being force-driven to the left of FIG. 4, from the position which is represented below the axis, so as to press the collar against the second outer face and to determine the displacement

  of material in the grooves When the diameter of

  As it increases, it is possible to exert an increased axial preload on the stem, as described in US Pat. No. 2,955,505, which is not

  indicated in this description only for reference.

  When using a helical groove, even if the tip diameter increases, the collar previously set up can then be removed by rotating it, simply by exerting sufficient force for the

  Thread moves the material of the collar during its rotation.

  To reduce the weight of the rod to a minimum value, the longitudinal resistances inherent to the head section and the peripheral groove are made substantially equal and it is not possible to indicate which part will present the first rupture.

  this resistance is chosen so as to present the

  least necessary to resist the long-term forces

  dinals which are determined by a flexion of the device

  Such values can easily be

  experts in these techniques, but it is obvious that only a section of the head

  very small and a very small collar stretch This particular

  larity reduces the weight of some short stems by up to 20% compared to

stems designed in a classic way.

  In view of the relatively abrupt and marked size change, the tool hardening of the intermediate section is of great importance and makes it possible to withstand the fatigue forces at this level.

critical junction.

  A thread obtained by a rolling-type operation has the additional advantage of hardening with the tool and makes it possible to obtain the same resistance with a

smaller collar section.

  The diameter of the tail is also determined

  at the time of conception It is chosen so as to re-

  to resist a predetermined shear force.

  The stem may be made of any suitable metallic material Aluminum alloys

  and titanium alloys are useful examples.

  A hardened material is generally preferred.

  Thus, the present invention makes it possible to provide a balanced rod which has only the necessary resistances for each of its various functions and which, therefore, can be made lighter in weight than the conventional fasteners. The result is also lighter while presenting the structural features that are needed. It is understood that the present invention has only been described and shown for explanatory purposes but

  in no way limiting and that any changes

  useful information, especially in the field of equivalences

  techniques, without going outside the scope.

Claims (19)

  1 balanced metal rod, for creep and shear fastening device, of the type comprising first and second ends and an axis of symmetry (30) and forming a fixing member, rod characterized in that it comprises a head section (21), a cylindrical tail section (22), a transition section (23), a collar section (24) and a peripheral groove (27) formed on the collar section, said sections being coaxial   in relation to each other and being arranged in the   dre indicated from the first end, the head section and the peripheral groove having respective inherent strengths so as to withstand the forces   longitudinal tension, and the cylindrical tail section   that having an inherent inherent resistance of   to withstand lateral shear forces, the   a cylindrical tail section with a determined diameter   born and the head and neck sections with dimensions   respective lateral sections, the diameter being smaller than all the lateral dimensions of the head section and greater than all the lateral dimensions of the neck section and the peripheral groove, the transition section   reducing the lateral dimensions of the stem between the   cylindrical shank and the collar section and comprising a shoulder (25) contiguous to the cylindrical tail section   and an unthreaded intermediate section (26) contiguous to the   the stem being made of a material that can be hardened with the tool and the intermediate section being hardened to the tool so as to better withstand the fatigue forces, the inherent strengths of the head section and throat peripheral being substantially equal and just   sufficient to withstand the forces of longitudinal traction   dinals exerted by bending the fastening device to   shear and shear, and the inherent resistance of the   cylindrical shank being sufficient to withstand the shear forces exerted in said creep and shear fixation.   Rod according to claim 1, characterized   'because the inherent resistance of the section   head and the peripheral groove are sufficiently   so that we can not determine who will present   the first rupture under the effect of tensile forces.   3 Rod according to claim 1, characterized in that the peripheral groove is constituted by a helical thread which is formed on the section collar, in particular by rolling.   Rod according to claim 1, characterized   because the peripheral groove is made up of   by a thread having a crown diameter which increases   as the thread moves away from the first end.   Rod according to claim 4, characterized in that the thread has a bottom diameter which is constant for part of the axial length of the thread.   Rod according to claim 1, characterized   because the peripheral groove is made up of   by at least one continuous annular groove.   Rod according to claim 1, characterized   because the head section is made up of   a head intended to be drowned.   Rod according to claim 1, characterized   because the head section is made up of   a head intended to protrude.   Rod according to claim 1, characterized   because the transition section between the   and the intermediate section is substantially normal to the axis.   Rod according to claim 1, characterized   because the transition section between the   and the intermediate section consists of a surface of revolution which is arranged at a non perpendicular to the axis.   Rod according to claim 1, characterized   due to the fact that the groove is constituted by a thread   which is made by rolling on the neck section, the section   1 intermediate layer being hardened to the tool, especially a wheel   Rod according to claim 11, characterized   due to the fact that the metal displaced by the hardening to the tool creeps to reach locations of the transition section and the neck section which are not in contact with a metal element or with a fastener forming the device fastening with said rod.   13 Creep and shear fastener   comprising a rod according to any one of   claims 1 to 12, characterized by the fact that   takes a fixing member intended to be fixed on said rod. 14 Apparatus according to claim 13, characterized in that the fastener is a collar. Device according to Claim 14,   characterized by the fact that the throat of the stem is a   helical thread and that the collar has a flat nut   RAUDE. Device according to Claim 15, characterized in that the collar comprises a drive means for applying a torque to the nut,   this training means can be separated during the application cation of a predetermined pair.   17 Apparatus according to claim 16, characterized in that a shear section is connected to the drive section of the nut so as to break for the predetermined torque and release the   drive section relative to the nut.   18 Apparatus according to claim 15, characterized in that the thread has a crown diameter which increases as the thread   departs from the first end.   19 Apparatus according to claim 14, characterized in that the collar is deformable by the discharge of the metal in the peripheral groove, in particular by repoussage.   Device according to claim 19, characterized in that the groove is a thread which has a crown diameter which increases as the thread moves away from the first end.   21 Creep and shear fixation device   two or more metal parts with aligned through holes, a first outer face on one of the parts and a second outer face on   another piece, and comprising a stem   conque of claims 1 to 12, characterized by the fact   that the rod passes through the holes so that its head bears against the first outer face and that its neck protrudes relative to the second outer face, the device comprising a collar which is fixed to the thread of the rod and which bears against the second outer face, this collar exerting, with the head section of the rod, a longitudinal traction force in the rod, the cylindrical tail section adapting to the holes so as to withstand   shear forces exerted between the pieces.   Device according to Claim 21, characterized in that the cylindrical tail section   is forced into the holes.   Apparatus according to Claim 21, characterized in that the collar comprises drive means for applying torque to the nut,   this training means can be separated during the application   cation of a predetermined pair and being eliminated at the   following the application of this couple.   Device according to Claim 21,   characterized by the fact that the collar has been repressed   metal in the throat, especially by repoussage.   Device according to Claim 21, characterized in that the groove is constituted by a threading which is produced at the level of the collar section, in particular by rolling, the intermediate section of the rod being hardened with the tool, in particular with the wheel, and the metal displaced by tool curing having crept into locations of the transition section and the neck section which are not in contact with the parts nor with the collar.