FR2683020A1 - BAR PROVIDED WITH A TUBULAR WALL IN COMPOSITE MATERIAL REINFORCED WITH FIBERS AND A CONNECTING ELEMENT PLACED AT ITS TWO ENDS. - Google Patents

Abstract

It is a bar provided with a tubular wall (6) of composite material reinforced with fibers, comprising at least one layer of unidirectional fibers parallel to the axis and, placed above, a tubular braid having fibers, which intersect at an angle to the axis of the bar, which bar is provided at both ends with a connecting element (12) with rotational symmetry, serving to axially transmit tensile forces and / or pressure, which is provided with a conical segment (13) contracting towards the end of the bar. The unidirectional fibers parallel to the axis lie along the entire length of the conical segment of the connector element against the surface thereof. The tubular braid is located in the area of the conical segment, with a decrease in the crossing angle of its fibers, against the layer of unidirectional fibers. The tubular wall (6) of unidirectional fibers and tubular braid protrudes at the ends of the bar (2) respectively above the front faces (14) of the connecting element directed outwards. At least in the conical sector of the connecting element, is placed a peripheral winding (36) of high resistance fibers, housed in a matrix of synthetic resin.

Description

BAR HAVING A TUBULAR WALL IN COMPOSITE MATERIAL

  REINFORCED WITH FIBERS AND A CONNECTING ELEMENT

TAKE PLACE TO ITS TWO ENDS.

  The present invention relates to a bar provided with a tubular wall of composite material reinforced by

  fibers, which has a layer of unidirectional fibers-

  nelles parallel to the axis and, placed above, a tubular braid comprising fibers, which cross at an angle with respect to the axis of the bar and a connecting element with rotationally symmetrical placed at each its two ends, serving to transmit axially tensile and / or pressure forces, which, surrounded by the wall, is provided with a coaxial connection thread, bar in which, in the region of the connection element, East

  placed a peripheral winding in high resistance fibers

  this housed in a synthetic resin matrix, the fibers of the unidirectional layer and of the tubular braid being,

  in the area of the outer end of the coupling element

cordage, sectioned.

  In the case of known bars of this type (DE 34 OO 043 Al), the connection elements are cylindrical and provided at their periphery with a flat circular groove which, towards the internal end of the connection element, passes in

  the outer periphery via a flattened arc.

  The fibers of the unidirectional layer are tightened in the circular groove by a peripheral winding made of high resistance fibers housed in a resin matrix

  synthetic and the tubular braid extends, through this

  peripheral bearing, up to the end of the bar,

  above the contiguous cylindrical zone of the connecting element

  dement. Such bars have the advantage of being able to be produced according to a quasi-continuous process. The force transmission, as regards both the tensile forces and the pressure forces, is nevertheless, with such bars, limited. We know bars with a core and, placed

  at both ends, connecting elements, which pre-

  feel a tapered segment tapering towards the end

  of the bar Bars of this type are provided with a reel

  in unidirectional fibers parallel to the axis, extending above the segment contracting into a cone

  peripheral windings are placed above the seg-

  conical elements of the connecting elements Here, the coil-

  peripheral device can be pre-stressed above the elements

  connecting elements The fibers parallel to the axis are fixed above the cylindrical segment of the bars by means of a peripheral winding It is furthermore

  known, for the establishment of the longitudinal layers, to use auxiliary winding cones, separated after hardening or, for l-cy-15 connecting elements to equip them with grooves on their periphery.

  The fibers parallel to the axis are placed here during

  of a winding process, at the same time as they are

  dice in the grooves and returned above the polar radius of the connecting element (BMFT-MT Report 6/79, pages 5

at 12, 65, 67 to 71).

  Another bar is known, which has elements

  of connection joined to a heart, which are provided ex-

  behind a conical segment, which may, towards the end of the connecting elements, have a curved step serving as a transition towards the cylindrical segment (GB-PS 1509892 and 1 551 223) In these bars, on the core, is placed a

  layer of unidirectional fibers parallel to the axis, au-

  above which a winding with layers in the form of a screw is placed and the winding direction of which is

  each time reversed, the winding process being controlled so that the slope in the conical sector is reduced

  te up to a winding angle of 90, before the next layer is rolled up These known bars can therefore only be produced individually On the connection element35 is screwed a union nut, which is provided with a shoulder, against which the end of the tabular wall made of fiber-reinforced composite material rests. Bars of this type also have only a low tensile and pressure resistance. manufacturing, winding diagrams are adapted

  for each bar length, depending on each of the pro-

  ceased and, therefore, the establishment of fibers requires expensive winders or special auxiliary devices. The problem of the present invention consists in making a bar of this type such that it can transmit significant tensile and / or pressure forces and which can be

  can manufacture it according to a simple process.

  This problem is solved in accordance with the present invention.

  tion with a bar provided with a tubular wall of fiber reinforced composite material, comprising at least one layer of unidirectional fibers parallel to the axis and, placed above in contact, a tubular braid having fibers, which cross by forming an angle with respect to the axis of the bar and a connection element with symmetry of revolution placed at each of its two ends, serving

  to transmit axially tensile and / or press forces

  sion, which, surrounded by the wall, is provided with a coaxial connection thread, bar in which in the area of the connection element is placed a peripheral winding made of high resistance fibers housed in a matrix of synthetic resin and

  the fibers of the unidirectional layer and the very

  being tubular being, in the area of the outer end of the connecting element, sectioned, characterized in that

  the connection element is provided with a conical segment

  that contracting towards the outside of the bar, the unidirectional fibers parallel to the axis are,

  over the entire length of the conical segment of the coupling element

  rope, all against the surface thereof, in the sector of the conical segment, the tubular braid is in contact against the layer of unidirectional fibers, with a decrease in the crossing angle of its fibers, the tubular wall in unidirectional fibers and in

  tubular braid protrudes at the ends of the bar

  pectively above the front faces directed towards the outside of the connection element, the peripheral winding is provided at least in the conical zone of the connection element, and that

  the conical segment of the connecting element presented

  te a cone tip angle, with which, after establishing a prestress exceeding the tensile force at

  support, the connection element is kept self-locking

  as in the conical end segment of the tubular wall

from the bar.

  An advantageous configuration of such a bar is

  characterized in that the conical segment of the connecting element

  cord has a cone tip angle between

8 and 100.

  Preferably the connecting element has a cylindrical segment connecting to the base of the conical segment and that between the cylindrical and conical segments is

  formed a rounded transition zone.

  According to another embodiment, the peri-winding

  spherical extends beyond the free end of the segment

  cylindrical of the connecting element Particularly

  The advantageously pressure discs, each configured with an annular flange which covers the tubular wall on the outside, are rigidly connected to the ends of the bar. Bars according to the present invention are thus

  remarkable for the fact that the pressure forces are trans-

  put directly frontally through pressure discs

  sion in unidirectional fibers.

  Bars according to the present invention can be manufactured in a quasi-continuous process for the manufacture of bars provided with a tubular wall of fiber-reinforced composite material on a core of algeolar product, which are connected on both sides to elements of connection

  with a coaxial thread used for trans-

  put tensile or pressure forces axially in the bar, process in which

  the connection elements are embedded in a section

  core lesson at distances, which are a function of the bar lengths at the same time as two neighboring elements are connected to each other by a spacer comprising threaded segments,

  that can be screwed into the thread of the connecting elements

  A minimum of one layer of unidirectional fibers parallel to the axis (layer UD) is placed on the horizontal core section, then, after impregnation of this layer with synthetic resin, a tubular braid, comprising fibers crossing at an angle to the axis, also impregnated after installation, the core section covered with the tubular braid is introduced into a shrinkable sheath, the latter being,

  under the effect of heat, gradually brought to the

  tact of the outer surface of the core section, the core section with the shrinkable sheath in place is kept in the stretched position during the hardening of the synthetic resin, the shrinkable sheath is removed after the hardening

  and the individual bars are obtained by sharing the section

  between the neighboring connection elements and

  in the area of the connection elements is placed

  ce a peripheral winding made of high strength fibers

  housed in a synthetic resin matrix.

  In the case of such a known method (DE 34 O O 043 Al), cylindrical connection elements are used, which are

  glued in a core section, interconnected by the

  set of grub screws The connecting elements cy-

  lindrics are provided on the periphery with circular grooves

  flat lairs After the fiber layer is in place

  unidirectional parallel to the axis, the windings peri-

  spherical, thanks to which the fibers parallel to the axis are compressed in the circular grooves and are held there, are put in place In this case, the ordered installation of a layer of fibers parallel to the axis in the circular groove is difficult to access These fibers are also strongly bent The tubular braid is then guided over these winding segments In the known method, the lengths of the individual bars must, after the installation of the tubular braid be cut

  between the connecting elements, then the main lengths

  its isolation must be hardened in a forming device. Starting from the process for the manufacture of bars provided with a tubular wall of fiber-reinforced composite material on a core of foam product, which are

  connected on both sides to metal connection elements

  liques comprising a coaxial thread used to transmit 1 O axially in the bar of the traction or pressure forces, process in which

  the connection elements are embedded in a section

  core lesson at distances, which are a function of the bar lengths, at the same time as two neighboring connection elements are connected together by a spacer comprising threaded segments, which can be screwed into the thread of the connection elements, on the horizontal core section, at least one layer of unidirectional fibers parallel to the axis (UD layer) is put in place, then, after impregnation of this layer with synthetic resin, a tubular braid comprising fibers crossing each other by forming an angle with respect to the axis, also impregnated after installation, the core section covered with the tubular braid is introduced into a shrinkable sheath, the latter being,

  under the effect of the heat, brought gradually, to the

  tact of the outer surface of the core section, the core section with the shrinkable sheath in place is kept in the stretched position, during the hardening of the synthetic resin, the shrinkable sheath is removed after hardening

  and the individual bars are obtained by sharing the section

  between the neighboring connection elements and

  in the area of the connection elements is placed

  that a peripheral winding of high resistance fibers housed in a matrix of synthetic resin, bars in accordance with the present invention can be manufactured in the following characteristic manner,

  connecting elements are used, which present

  tent a conical surface contracting towards the outside of the bar,

  neighboring connection elements are, on the

  teurs, kept at a distance from each other such that the unidirectional fibers and the tubular braid can be compressed between the connecting elements at a cone tip angle, which is equal to or slightly greater than 1 '

  cone tip angle of the connecting elements.

  after the hardening of the wall, the bars are, transversely to the axis of the bar, cut off at a distance before the external front face of the connection elements and after the separation of the bars, peripheral windings are put in at least on the tubular body

  in the conical areas of the connecting elements.

  In this process, it is advantageous to place a plastic tube on the spacer, between the connection elements. The present invention is illustrated by way of example in the appended drawings and described in detail below with the aid of these, in which:

  Figure 1 is a longitudinal section of a bar

  form to the present invention, comprising connecting elements, which are fixed thereto; Figure 2 shows a connection element for the bar of Figure 1; Figure 3 shows, on a larger scale, a longitudinal section through the end of the bar having a modified embodiment of the pressure disc; Figure 4 is a schematic representation of the manufacturing process;

  Figure 5 shows a large-scale stage of the pro-

yielded from manufacturing.

  The bar 2 shown in FIG. 1 has a non-deformable core 4 of cellular material, to which connecting elements 12 are connected at its two ends. The bar 2 is provided, in a known manner, as in the document.

  DE 34 00 043 A1, of a thin tubular wall 6, which comprises

  laying, in a synthetic resin matrix, an inner layer of unidirectional fibers parallel to the axis and, placed above in contact with a tubular braid presenting fibers, which cross at an angle by relative to the axis of the bar, which are not shown

  separately in the accompanying drawings.

  The connection elements 12, via which forces are transmitted axially in the bar, comprise, as can be seen in FIG. 2, a conical segment 13 tapering towards the connection end 14 At the opposite end 14 a is provided, following, a cylindrical segment 15 Between these two segments, a rounded transition zone 13 a is provided In order to reduce the weight, the connecting piece 12 is, as much as possible, provided with a cavity starting from the end 14 a In addition, the connection element is provided with a coaxial thread 22, in

  which it is possible to screw connection fittings

  ment 10 The connection set comprises a screw 18 provided with a connecting eye, with a threaded segment 19, which

  it can be screwed into the connection element 12 and onto the

  which is placed a nut 20 and a pressure disc 16.

  The tubular wall 6 rests by the unidirectional fibers-

  on the core and on the segments 15, 13 a and 13 of the connecting element 12 and the tubular braid is stretched in the transition sector of the zone 13 a and of the conical segment 13 to adapt to the angle 24 cone tip, in

  this sector the crossing angle of the fibers of the tubular braid

  the area relative to the axis of the bar being thus comparatively smaller than in the cylindrical zones of the core and

of the connecting element.

  As shown in Figures 1 and 3, along the length of the connecting element 12 and preferably further on

  a limited segment of the tubular wall of the bar is placed

  in a synthetic resin matrix, a winding

  peripheral 36 in high resistance fibers The front face

  the 24 of the tubular wall 6 extends beyond the end of

  its conical segment, the end 14 of the connecting element

  ment 12 of an overhang d A prestress of the peripheral winding 36 is possible thanks to this overhang The angle

  cone tip 2 ci is chosen so that, by workbench-

  s of a suitable prestress in the peripheral winding, the connection element is kept self-locking in the conical end segment of the tubular wall of the bar. The angle of the cone tip 2 d 1 must not be chosen too small, in order to avoid an overload of

  the peripheral winding A cone tip angle appro-

prayed is between 8 and 100.

  For prestressing, as shown in Figure 3, a clamping screw 40 can be screwed into 1 '

  prestressing element, by means of which through

  middle of a pressure disc 16 placed on the screw, which may be the pressure disc of the connection lining, is generated against the front face 24 of the tubular wall

  a pressure force as a reaction force to the force

  this tensile force generated on the connection element by means of the clamping screw 40 The tensile force must exceed by a determined amount the maximum tensile force to be transmitted Under this preload, the overhang d shrinks and with l 'cone tip angle chosen, self-locking is ensured, so that by means of the connecting element 12, without displacement of the connecting elements in the tubular wall 6, it is thus possible to transmit without hysteresis of the pressure and / or traction forces. For the transmission of pressure and traction forces,

  the length of the tubular wall is available at each point

  laire, of the entire section of the fibers parallel to the axis, which rests frontally against the pressure disc 16, which, in the embodiment of FIG. 1, rests by a flat radial surface against the front face 24 of the tubular bar 6 The

  pressure disc 16 can also be configured with a collar

  circular lug 17, which, when installing the disc

  pressure against the front face 24 of the wall 6, covered

  externally sees a limited segment of this wall, as

seen in Figure 3.

  The pressure disc 16 can, in both embodiments, be provided with key surfaces and bores or

  grooves for securing wires or safety discs For this purpose, the flange 17 of the pressure disc 16 covering the tubular wall is available, in the embodiment of FIG. 3.

  The pressure disc can, in both forms of

  realization, also serve as a wall limiting the es

  winding space for the peripheral winding 36 It is then permanently connected to the peripheral winding or to

  the end of the bar, thus constituting an integrated element

  gral of it The bar 2 can, for the establishment of the peripheral winding, be housed capable of turning and be provided with a rotation control For the rotary housing, can be screwed into the connecting element 12 a screw 40, in the head of which a centering bore 42 is provided, by which the pressure disc 16 is pressed

  against the front face of the fibers parallel to the axis.

  With regard to the manufacture of bars, as shown in the accompanying drawings and described in the foregoing, a process can be used, such as that described in document DE 34 OO 043 A1, steps

  essential, and that figure 4 illustrates For the manufacture-

  tion of the bars, a core section is used, which is composed of segments 46 of radially deformable cellular product, and which can be glued from several core segments The length of the core segments 46 is chosen according to the bar lengths respectively

  desired At the ends of the core segments,

  tively fixed, glued for example, the connecting elements

  externally conical 12 of the bars The connecting elements are joined together by means of a

  spacer section 48, which is screwed by means of file segments

  tees in the connection elements Other particulars

  These are described below with reference to Figure 5.

  The core section 44 rests on a support 50 and is guided thereon in a longitudinal direction. On the core section 44 is placed externally, by means of a device 52, a layer of unidirectional fibers, as the UD layer. The fibers 54 are, in the example shown, unwound from reels 56 and they go, by means of guide rollers 58 on a guide ring 5 60, in which they are placed annularly to then come under a guide ring 62, through which

  they are brought into contact with the surface of the core section 54 possibly impregnated with synthetic resin. The core section comprising the layer UD applied to it 10 is then guided through an impregnation device 64.

  The UD layer can also be put in place, in a known manner, in the form of prefabricated UD strips. On the UD layer 63, a tubular braid 68 is then put in place, which can, for example, come from a magazine 66 on which a determined length of tubular braid 68 is stored

  in compressed form The tubular braid is then reti-

  store layout and tightly positioned on the surface of the UD layer The section thus prepared is then threaded

  in a shrinkable sheath 70, another impregnation device

  gnation and scraping can be inserted in front

  the entry of the section into the shrinkable sheath, a winding

  ment or the like is placed on the tubular braid in the middle region of the retractor, winding on which

a contraction is exerted.

  After the introduction of the section, the shrink tubing is

  lesson, gradually heated starting at its end

  rear and caused to shrink As a result, the sheath shrinks

  cissable comes, without the formation of air bubbles, in contact with the surface soaked in synthetic resin Having regard to the

  heat absorbed by the shrinkable sheath, the syn-

  thetic is simultaneously heated and thus its viscosity decreases. As a result, the pressure generated simultaneously by the shrinkable sheath improves the impregnation of the fibers taken in isolation. Simultaneously, the excess synthetic resin is extracted from the fibers and

  of the fibers and, by progressive application of the cheerfulness

  not shrinkable, taken to the end of the section.

  Finally, the section is then removed in the desired configuration, prismatic for example, for the hardening of the synthetic resin After hardening the shrinkable sheath is removed, the section is divided between two

  neighboring connecting elements, and the tubular wall is dry

  operated transversely to the axis of the bar also at a certain distance in front of the external front faces of the

connection elements 12.

  Other features appear in Figure 5.

  On the spacer shown here in the form of a threaded rod 48, the two connecting elements 12, opposite one another in the section 44, of two successive bars are kept at a distance D, such that, by the intermediary

  an auxiliary winding 74, it is possible to obtain a

  conical cementation, which is large enough for the fibers of the UD layer 63 and the tubular braid 68 to be kept in close contact against the surface of the conical segment of the connecting elements 12 A suitable winding station can be provided between the outlet of shop 66 and inlet of shrink tubing. 20 The threaded rod 48 can, as shown in FIG. 5, be provided with a complete thread.

  also threaded bolts with file segments-

  tees at both ends, which could possibly be

  provided with stop collars resting against the front surface

  tale 14 of the connecting elements 12 In order to protect

  the threaded rods on the one hand against the penetration of resi-

  and on the other hand against damage during the sectioning of the tubular layer, a protective tube 78, made of synthetic material for example, and which can serve simultaneously as a spacer, can be placed on the threaded rod.

  protection 78 can simultaneously be used to limit the

  fiber scarring due to auxiliary winding 74.

  With the process described, it is possible to manufacture

  almost continuous bars, that is to say that one can

  as passage through the device to manufacture a plurality of bars No complicated winding device is necessary for the manufacture of the bars, although, for mass production, it is also possible to provide braid devices or winding devices for making the

tubular braid.

  The auxiliary winding 74 can optionally, in

  the sector between the connecting elements, under condi-

  tions, can also be carried out by hand. Here again, no winding can be placed for the application of the shrinking force. On the contrary, provision can also be made for the installation of circular fixing flanges, which can be shared. radially, but we can also

  use radially expandable domed elastic washers

  Also, as we know them for fixing pipes. After placement and hardening of the peripheral winding 36, is

  applied a tensile force to the bar through the connecting elements in order to obtain a tension state without hysteresis, this tensile force exceeding by a predetermined amount the tensile force

  maximum for which the bar is designed.

Claims (6)

RESELL ICAT IONS   1 Bar provided with a tubular wall made of a material   fiber-reinforced posite, comprising at least one layer of unidirectional fibers parallel to the axis and, placed above it in contact, a tubular braid   so many fibers, which cross at an angle with respect   port to the axis of the bar and a connecting element to   symmetry of revolution placed at each of its two extremi-   tees, used to transmit axially tensile and / or pressure forces, which, surrounded by the wall, is provided with a coaxial connection thread, bar in which in the area of the connection element is placed a peripheral winding made of high strength fibers housed in a synthetic resin matrix and the fibers of the unidirectional layer and of the tubular braid being, in the region of the outer end of the connecting element, sectioned, characterized in that the element connection (12) is provided with a conical segment (13) contracting towards the end of the bar, the unidirectional fibers (60) parallel to the axis are, over the entire length of the conical segment of the element connection, all against the surface of the latter, in the sector of the conical segment, the tubular braid (68) is in contact against the layer of unidirectional fibers with a reduction in the crossing angle of its fibers, the tubular wall (6) in unidirectional fibers and in tubular braid protrudes at the ends of the bar (2) respectively above the front faces (14) directed towards the outside of the connection element the winding peripheral (36) is provided at least in the conical region of the connection element,   and in that the conical segment (13) of the coupling element   cord (12) has a cone tip angle (2 U), with which, after establishment of a Prestressing which exceeds the tensile force to be supported, the connection element is kept self-locking in the conical end segment of the tubular wall (6) of the bar.   2 Bar according to claim 1, characterized in that   the conical segment (13) of the connecting element (12) pre-   feels a cone tip angle (2 A) between 8 and 10.   3 Bar according to one of claims 1, 2, character-   in that the connecting element (12) has a segment   cylindrical (15) connecting to the base of the conical segment   that (13) and in that between the S cylindrical segments conical zet   a rounded transition zone (13 a) is formed.   4 Bar according to claim 3, characterized in that the peripheral winding (36) extends beyond the end   free of the cylindrical segment (15) of the connecting element ment (12).   Bar according to claim 1, characterized in that   pressure discs (16) each configured with a collar   the annular collar (17) which covers the tubular wall (6) externally, are rigidly connected to the ends of the bar. 6 Method for the production of bars provided with a tubular wall made of fiber-reinforced composite material on a core of cellular product, which are connected on both sides to metallic connection elements comprising a coaxial thread serving to transmit axially in the   tensile or pressure bar, process in the- what   the connection elements are embedded in a section   core lesson at distances, which are a function of lengths   bar, together with two connecting elements   sins are interconnected by a spacer comprising seg-   threaded elements, which can be screwed into the threads of the connection elements, on the horizontal core section, at least one layer of unidirectional fibers parallel to the axis (UD layer) is placed which, after impregnation of this layer with synthetic resin, a tubular braid comprising fibers crossing at an angle to the axis, also impregnated after installation, the core section covered with the tubular braid is introduced into a shrinkable sheath, that -this being, under the effect of heat, brought gradually into contact with the outer surface of the core section, the core section with the shrinkable sheath put in place is kept in the stretched position during the hardening of the synthetic resin, the shrinkable sheath is removed after hardening   and the individual bars are obtained by sharing the section   between the neighboring connecting elements, and   in the area of the connection elements is placed   ce a peripheral winding made of high resistance fibers housed in a matrix of synthetic resin, characterized in that   connecting elements (12) are used, which pre-   feel a conical surface (13) contracting outwards   laughing bar, neighboring connecting elements (12) are, on the spacers (48), kept at a distance from each other such that the unidirectional fibers (60) and the tubular braid   (68) can be compressed between the connecting elements at a cone tip angle (2 L), which is equal or slight   slightly greater than the cone tip angle of the connecting elements, after the wall has hardened, the bars are, trans-   versally to the axis of the bar, sectioned at a distance before the external front face of the connection elements and   after the bars have been separated, the peripheral windings   risks are placed on the tubular body, at a minimum   in the conical areas of the connecting elements.   7 Method according to claim 6, characterized in that   that the force causing the narrowing after the contraction   tion of the shrink tubing is applied externally on the latter.   8 Method according to claim 6, characterized in that a plastic tube is placed on the spacers   between the connecting elements.