Method of assembling at least two units, and a corresponding assembled structure

Abstract

A method wherein a first unit (10) is provided having a field of grip elements (12), and a second unit (20) provided with retention elements (22) suitable for co-operating with the grip elements (12) of the first unit (10) in order to provide a self-gripping fastening. The first and second units are put into contact in such a manner that the grip elements (12) of the first unit and the retention elements (22) of the second unit provide a self-gripping fastening (F). A treatment zone of the self-gripping fastening is treated in order to deform the grip elements (12) of the first unit (10) and/or the retention elements (22) of the second unit (20), whereby the first and second units (10, 20) are permanently secured to each other, thereby forming an assembled structure.

Claims

1. A method comprising: providing a first unit having a field of grip elements and a second unit provided with retention elements suitable for co-operating with the grip elements of the first unit in order to provide a self-gripping fastening; putting the first and second units into contact in such a manner that the grip elements of the first unit and the retention elements of the second unit provide the self-gripping fastening; and treating a treatment zone of the self-gripping fastening through a treatment in order to deform the grip elements of the first unit and/or the retention elements of the second unit, whereby the first and second units are permanently secured to each other, thereby forming an assembled structure, wherein the treatment zone represents at least 50% of a total extent of the self-gripping fastening.

2. The method according to claim 1, wherein the treatment is such that after being deformed, the grip elements or the retention elements form reinforcing elements of the assembled structure.

3. The method according to claim 1, wherein the treatment is such that after being deformed, the grip elements or the retention elements retain a shape that is generally unchanged.

4. The method according to claim 1, wherein the treatment zone forms a continuous line.

5. The method according to claim 1, wherein the retention elements comprise fibers.

6. The method according to claim 1, wherein the grip elements and/or the retention elements are made of thermoplastic material.

7. The method according to claim 1, wherein the treatment comprises applying pressure to the self-gripping fastening.

8. The method according to claim 1, wherein the treatment comprises heat treatment.

9. The structure obtained by performing the method according to claim 1.

10. The method according to claim 1, wherein the grip elements include hooks.

11. The method according to claim 1, wherein the treatment zone represents at least 80% of a total extent of the self-gripping fastening.

12. A method comprising: providing a first unit having a field of grip elements and a second unit provided with retention elements suitable for co-operating with the grip elements of the first unit in order to provide a self-gripping fastening; putting the first and second units into contact in such a manner that the grip elements of the first unit and the retention elements of the second unit provide the self-gripping fastening; treating a treatment zone of the self-gripping fastening through a treatment in order to deform the grip elements of the first unit and/or the retention elements of the second unit, whereby the first and second units are permanently secured to each other, thereby forming an assembled structure; providing a third unit comprising a field of grip elements suitable for co-operating with the retention elements of the second unit in order to provide a self-gripping fastening; putting the second and third units into contact so that the second unit is arranged between the first and third units, and the grip elements of the third unit and the retention elements of the second unit provide a second self-gripping fastening; and treating a treatment zone of the second self-gripping fastening to deform the grip elements of the third unit and/or the retention elements of the second unit, whereby the second and third units are permanently secured to each other.

13. The method according to claim 12, wherein the self-gripping fastenings provided between the second unit and the first and third units respectively are treated simultaneously in a single treatment step.

14. The method according to claim 12, wherein prior to the treatment, the grip elements of the first unit and the grip elements of the third unit are put into co-operation, the retention elements of the second unit lying between said grip elements.

15. The structure obtained by performing the method according to claim 12.

16. A method comprising: providing a first unit having a field of grip elements and a second unit provided with retention elements suitable for co-operating with the grip elements of the first unit in order to provide a self-gripping fastening; putting the first and second units into contact in such a manner that the grip elements of the first unit and the retention elements of the second unit provide the self-gripping fastening; treating a treatment zone of the self-gripping fastening through a treatment in order to deform the grip elements of the first unit and/or the retention elements of the second unit, whereby the first and second units are permanently secured to each other, thereby forming an assembled structure, wherein the first and second units form respective longitudinally-extending strips, the first and second units being superposed continuously in a longitudinal direction over at least one contact zone where the grip elements of the first unit and the retention elements of the second unit provide the self-gripping fastening, and said self-gripping fastening is treated continuously in the longitudinal direction over at least one treatment zone.

17. The structure obtained by performing the method according to claim 16.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure can be well understood and its advantages appear better on reading the following detailed description of various implementations shown as non-limiting examples. The description refers to the accompanying drawings, in which:

(2) FIG. 1 is a perspective view showing two units that are to be assembled together by a first implementation of the method of the present disclosure;

(3) FIG. 2A is a side view of two FIG. 1 units, prior to being put into contact;

(4) FIG. 2B is a side view of the two FIG. 1 units connected together by a self-gripping fastening;

(5) FIG. 2C is a side view of the structure that results from final assembly of the first and second units of FIG. 1;

(6) FIG. 3 is a diagram showing the treatment zone of the FIG. 2B self-gripping fastening;

(7) FIGS. 4A to 4C show variant distributions for the treatment of the self-gripping fastening of FIG. 2B;

(8) FIG. 5A is a section showing three units that are to be assembled together by a second implementation of the method of the present disclosure, the unit being shown prior to being put into contact;

(9) FIG. 5B is a section showing the three units of FIG. 5A connected together by a self-gripping fastening;

(10) FIG. 5C is a section of the structure that results from final assembly of the three units of FIG. 5A;

(11) FIG. 6 shows a variant of the second implementation of the method of the present disclosure;

(12) FIGS. 7A to 7C show successive steps in a third implementation of the method of the present disclosure;

(13) FIG. 8 shows a first variant of the third implementation of the method of the present disclosure;

(14) FIG. 9 shows a second variant of the third implementation of the method of the present disclosure;

(15) FIG. 10 is an overall view of a commonly-used diaper;

(16) FIG. 11 shows a line for fabricating hook-carriers for diapers by implementing the method of the present disclosure;

(17) FIGS. 12A and 12B are sections respectively on XIIA-XIIA and XIIB-XIIB of FIG. 11;

(18) FIG. 13 shows a base that is to be reinforced locally by a reinforcing insert;

(19) FIGS. 14A to 14D are sections on XIV of FIG. 13 showing the various steps of assembling the reinforcing insert;

(20) FIGS. 15A and 15B show a variant implementation of the assembly method of FIGS. 13 and 14A to 14D; and

(21) FIG. 16 shows a variant of the reinforcing method of FIGS. 13 and 14A to 14D.

DETAILED DESCRIPTION OF IMPLEMENTATIONS

(22) FIGS. 1 to 3 show how a structure 100A (see FIG. 2C) is made by assembling together a first unit 10 and a second unit 20 in a first implementation of the method of the present disclosure.

(23) The first unit 10 is made out of a first thermoplastic material M1 that melts at a temperature T1, in particular a curable polymer such as polyethylene for which T1 is equal to 120 C. In the particular example of FIGS. 1 to 3, the first material M1 also contains a plurality of metal particles 40 that perform a function that is described in detail below in the present disclosure.

(24) As shown in FIG. 1, the first unit 10 comprises a base 11 defined by two main surfaces 11a and 11b, which surfaces in this example are rectangular, substantially plane, and parallel, being of length L1 and of width 11.

(25) A plurality of grip elements 12 project from one of these main surfaces 11a (referred to below as the junction surface), forming a field 13 of grip elements. By way of example, the grip elements 12 may be injection molded together with the base 11. They are thus integral with the base 11, in other words forming a single piece therewith, without any interface or discontinuity, in particular at microscopic level, where they join the base 11.

(26) In this example, the grip elements 12 are hooks, each comprising a stem 14 projecting from the junction surface in a direction that is substantially orthogonal to said surface, and a grip portion 15 that overlies said stem 14 and has two grip tabs extending laterally from the stem, on either side thereof.

(27) In the example, the field 13 of hooks extends over the entire width 11 and the entire length L1 of the base 11. Naturally, this distribution could be very different depending on the intended application. The grip elements may cover only a portion of the surface of the first unit from which they project, e.g. at least 95%, or indeed less than 5%.

(28) The grip elements 12 advantageously present a total height measured orthogonally to the surface 11a of the base 11 that lies in the range 0.1 mm to 5 mm, and the density of the field lies in the range 1 element/cm.sup.2 to 2000 elements/cm.sup.2.

(29) The second unit 20 is made of a second thermoplastic material M2 that melts at a temperature T2 higher than T1, in particular a polymer such as a polyamide for which T2 is equal to 260 C.

(30) The second unit 20 presents a structure that is very similar to the structure of the first unit 10, and it is therefore not described in detail below. It likewise comprises a base 21 defined by two surfaces 21a and 21b that in this example are substantially plane and rectangular, of length L2 (identical to L1 in this example) and of width l2 (identical to L1 in this example).

(31) As shown in FIG. 1, the second unit 20 has retention means 22 adapted to co-operate with the grip elements 12 of the first unit 10.

(32) In the example, the retention means 22 are grip elements complementary to the hooks 12, and in particular they are hooks of the same shape, forming a field 23 of hooks.

(33) The field 23 of hooks of the second unit 20 in this example occupies only a fraction of the junction surface 21a from which it projects.

(34) During assembly, and as shown in FIG. 2A, the first and second units 10 and 20 are positioned in such a manner that their respective junction surfaces 11a and 21a face each other.

(35) As shown in FIG. 2B, the first and second units 10 and 20 are then brought into contact in a desired relative position.

(36) In FIGS. 2B and 3, in particular, reference C designates the zone of contact between the first and second units 10 and 20. In this zone of contact C, the fields 13 and 23 of hooks of the first and second units 10 and 20 face each other in at least a determined zone, where they provide a self-gripping fastening referenced F resulting from co-operation between their grip elements 12 and 22.

(37) In this state, said self-gripping fastening F holds the first and second units 10 and 20 stationary relative to each other in a direction orthogonal to their junction surfaces 11a, 21a, and also in directions tangential to those surfaces. Nevertheless, they are not held permanently, and it is easy for the two units 10 and 20 to be separated in order to be repositioned, should that be necessary.

(38) Finally, and as shown in FIG. 2C, the self-gripping fastening F is treated in a treatment zone (referenced Z and represented by stippling in FIG. 3) corresponding in this example to the entire zone of the self-gripping fastening F, so as to secure the first and second units 10 and 20 together in permanent manner.

(39) Nevertheless, this example is not limiting. In certain circumstances, the treatment zone Z may extend over a fraction only of the self-gripping fastening F. In the example of FIG. 4A, the treatment zone Z is thus in the form of a strip extending over only a fraction of the length of the self-gripping fastening F, but extending all the way across the first and second units 10 and 20 along a continuous line, extending in the width direction in this example. In the examples of FIGS. 4B and 4C, the treatment zone Z comprises a plurality of strips, extending parallel to one another or forming a grid. In other variants, the treatment zone may also be in the form of a plurality of spots or the equivalent.

(40) In the example of FIGS. 1 to 3, the treatment zone Z is subjected to a temperature T that is higher than T1 but lower than T2, thereby causing the first unit to be deformed in said zone.

(41) The metal particles 40, which should be understood to be optional, serve in this example to ensure that temperature increases rapidly and uniformly within the first material.

(42) As shown in FIG. 2C, the base 11 and the hooks 12 of the first element 10 melt so as to coat the hooks 22 of the second unit 20 that have remained intact (since they do not deform).

(43) In order to ensure that treatment is effective, avoiding deformation of the hooks 22 of the second unit, the difference between the respective melting temperatures T1 and T2 of the first and second materials M1 and M2 should be not less than 5 C., preferably not less than 10 C., and more particularly not less than 20 C.

(44) The resulting assembled structure 100A is a one-piece block comprising a first layer 51 including the retention means for a self-gripping fastening, specifically the hooks 22, and a second layer 52 co-operating with the first layer 51 over at least one assembly zone 55 and holding captive the retention means 22, whereby the first and second layers 51 and 52 are permanently secured to each other.

(45) The structure 100A thus forms a composite element having a matrix formed by the material of the second layer (resulting from the deformation of the first unit) and the reinforcing means are formed by the grip elements of the first layer 51, serving in particular to improve the shear and/or traction strength of the structure.

(46) In a variant, it should be observed that the melting temperature of the first unit could equally well be higher than the melting temperature of the second unit.

(47) FIGS. 5A to 5C show a structure 100B (see the figure) that is made by assembling together a first unit 10, a second unit 20, and a third unit 30 in a second implementation of the present disclosure.

(48) As shown in FIG. 5A, the first unit 10 is similar to that described with reference to FIG. 1 in particular. It is therefore not described again.

(49) In this example, the second unit 20 is constituted by a layer of non-woven material, made out of a thermoplastic material that melts at a temperature T2, higher than T1. The retention means 22 of the second unit 20, which are adapted to co-operate with the hooks 12 of the first unit 10, are formed by the tangled fibers constituting the non-woven material.

(50) A non-woven material is made up of a plurality of fibers that are bonded together and that generally form a sheet. The fibers may be bonded together mechanically, chemically, or thermally. Three major types of non-woven material are presently known: dry-laid nonwovens (carded thermobondedairlaid thermobondedspunlaceairthroughcarded needle punched, etc.); wet-laid nonwovens; and spunmelt nonwovens (spunbond, meltblown, or a combination of both (SM, SMS, SMMS, SSMMS, . . . ), electrospun, melt-film fibrillated, solvent-spun, . . . ).

(51) The third unit 30 is made of a meltable polymer material that, in this example, is identical to the material M1 constituting the first unit 10.

(52) In the same manner, its structure is similar to that of the first unit 10. It thus comprises a base 31 defined by two substantially plane and parallel surfaces 31a and 31b together with a plurality of grip elements 32 adapted to co-operate with the retention means 22 of the second unit 20. In the example, these grip elements 32 form a field 33 of hooks projecting from one of the surfaces 31a of the base 31 (referred to below as the junction surface).

(53) During assembly, and as shown in FIG. 5B, the first and second units 10 and 20 are put into contact in a desired position. The fibers 22 of the second unit co-operate with the hooks 12 of the first unit 10 to provide a first self-gripping fastening F1.

(54) In the same manner, the second unit 20 and the third unit 30 are put into contact in a desired position. The fibers 22 of the second unit 20 co-operate with the hooks 12 of the third unit 30 to provide a second self-gripping fastening F2.

(55) By means of these self-gripping fastenings F1 and F2, all three units 10, 20, and 30 are held in position relative to one another. If they are poorly positioned, they can easily be detached and then repositioned, and this can be done a large number of times without damaging them.

(56) In the example, the three above-mentioned units 10, 20, and 30 are assembled together permanently by heat treatment, which consists in subjecting the stack to a temperature T that is lower than T2 but higher than T1.

(57) Under the effect of heat, the first and third units 10 and 30 deform and bond together, holding captive the fibers 22 of the non-woven material, which fibers themselves remain substantially intact, with the first, second, and third units thus being permanently secured to one another.

(58) As shown in FIG. 5C, the resulting assembled structure 100B is a composite unit comprising a first layer 51 including retention means that have been used in a self-gripping fastening, specifically the fibers 22, and a second layer 52 resulting from the deformation of the first and third units, co-operating with the first layer 51 over at least one assembly zone and holding the retention means 22 captive, whereby the first and second layers 51 and 52 are permanently secured to each other.

(59) The fibers 22 form reinforcing means for the assembled structure 100B, serving in particular to increase its stiffness and its traction strength, and preventing the first and third units 10 and 30 from separating. In a variant implementation shown in FIG. 6, the positioning of the three units 10, 20, and 30 may be secured further in additional manner by bringing the hooks 12 of the first unit 10 and the hooks 32 of the third unit 30 into mutual co-operation prior to applying the heat treatment.

(60) As can be seen from the above, the method of the present disclosure can advantageously be used in order to form a reinforced structure. A third implementation of the method of the present disclosure illustrates such a use and is shown diagrammatically in FIGS. 7A to 7C.

(61) In this example, a first unit 10 that is to be reinforced is made of a polymer material that melts at a temperature T1, and is substantially identical to the first unit described above with reference in particular to FIG. 1.

(62) A second unit 20 that is formed by a layer of non-woven material constituted by tangled fibers 22 (see FIG. 7A) is put into contact with the junction surface 11a of the first unit 10 from which its grip elements 12 project, so that said fibers 22 co-operate with the hooks 12 of the first unit 10 in order to provide a self-gripping fastening F.

(63) In this position, as shown in FIG. 7B, the layer of non-woven material is held stationary relative to the first unit in directions that are tangential to the junction surface 11a and in a direction orthogonal thereto.

(64) Thereafter, the self-gripping fastening F is subjected to a temperature T that is higher than T1 but lower than T2, e.g. obtained by using a sonotrode to generate ultrasound vibration. In this position, the base 11 and the hooks 12 of the first unit melt, and they coat the fibers 22 of the non-woven material, which fibers remain substantially intact.

(65) The first and second units 10 and 20 then constitute a single-piece assembled structure 100C of composite form, as shown in FIG. 7C, comprising a layer forming a matrix 52 that results from deformation of the first unit, holding captive the retention means for a self-gripping fastening, specifically the fibers 22.

(66) In a first variant of this third implementation, shown in FIG. 8, the first unit 10 is made of a material that melts at a temperature T2 higher than the melting temperature T1 of the second unit 20.

(67) When the self-gripping fastening F made between the two units is treated by being subjected to an intermediate temperature, higher than T1 but lower than T2, the fibers 22 melt and coat the hooks 12, that have themselves remained intact.

(68) The first and second units 10 and 20 then constitute a single-piece structure 100D of composite form comprising a matrix (resulting from deformation of the second unit 20) reinforced by the hooks 12 of the first unit 10.

(69) In a second variant implementation shown in FIG. 9, the self-gripping fastening F is treated by being subjected to a temperature that is higher than the melting temperatures of the first and second units 10 and 20.

(70) Under such circumstances, under the effect of high temperature, the hooks 12 melt while nevertheless retaining a generally substantially cylindrical shape.

(71) The fibers 22 melt and serve to coat the deformed hooks 12.

(72) The method of the present disclosure has a wide variety of applications in numerous fields. Non-exhaustive examples are given below.

(73) By way of example, the method of the present disclosure may advantageously be used in the field of hygiene, in particular for fabricating hook-carriers for closing diapers.

(74) The method of the present disclosure may also be used in the automotive or aviation fields, in particular for fastening trim on doors, roof panels, or covers.

(75) FIGS. 10, 11, 12A, and 12B show a particular application of the method of the present disclosure for fabricating hook-carriers for diapers.

(76) A diaper 60 of the kind shown in FIG. 10 usually comprises: a main or pant portion 62 having an inside face for coming into contact with the baby's skin and generally presenting an internal portion that is absorbent and an external portion that is waterproof; a front strip 64 centered on a plane of symmetry P of the diaper, fastened to the front of the pant portion 62 and presenting on its outside surface fibers 65, in particular loops, that are to co-operate with self-gripping hooks; two tabs 66, that are generally elastic, being fastened to the back of the pant portion 62 (on either side of the plane of symmetry P of the diaper 60); and two hook-carriers 100F provided with self-gripping hooks that are to co-operate with the loops of the front strip in order to close the diaper 60 (as shown in FIG. 10), each hook-carrier 100F being fastened to a respective one of the tabs 66.

(77) As shown in FIG. 10, a hook-carrier 100F generally comprises a support portion 72 comprising fibers (generally in a non-woven material) and that is fastened to the tabs 66 (generally by heat sealing) and a fastener portion 74 that is provided on a front face with self-gripping hooks 12 that are to co-operate with the loop-forming fibers of the front strip 64 of the diaper 60, in order to close said diaper.

(78) In conventional manner, these two portions 10 and 20 can be assembled by attaching the rear face of a tape without hooks on a non-woven tape by means of heat sealing or adhesive. These methods present the drawback of requiring guide means for the tape that are accurate and reliable in order to ensure they are properly prepositioned prior to heat sealing or using adhesive. Furthermore, the traction strength of hook-carriers obtained in this way is sometimes insufficient, leading to the support and fastener portions unsticking or separating.

(79) The assembly method of the present disclosure enables the above-specified problems to be solved.

(80) FIG. 11 shows the method being applied on a hook-carrier fabrication line.

(81) A first unit 10 in this example is in the form of a fastener tape of width 11 extending in a longitudinal direction X1 and having a junction face 11a covered in a field 13 of hooks, and a second unit 20 that is constituted by a support tape made of non-woven material, of width 12 and extending in a longitudinal direction X2.

(82) In a first step represented by the segment referenced T1 in FIG. 11, the first and second tapes 10 and 20 are arranged parallel to each other and continuously superposed in a longitudinal or machine direction X over a contact zone C of width lc, the support tape 20 thus covering part of the junction face 11a of the fastener tape 10.

(83) In the contact zone C, the hooks 12 of the fastener tape 10 and the fibers 22 of the support tape 20 provide a self-gripping fastening F. In this example the fastening F extends over all of said contact zone C.

(84) The two tapes 10 and 20 are superposed in such a manner that a free portion 18 of the fastener tape 10 carrying the hooks 12, and a free portion 28 of the support tape 20, are preserved on either side of the contact zone C.

(85) FIG. 12A shows the first and second units 10 and 20 at the end of this first step. The two tapes 10 and 20 are held in position relative to each other by the self-gripping fastening F, and there is no need for additional guide and holder means.

(86) In the second step illustrated by the segment T2, the self-gripping fastening F is treated continuously in the machine direction X.

(87) In this example, the treatment zone Z extends over the entire zone of contact C, and the treatment is performed by means of a wheel M, in particular a heater wheel, applying pressure against the two tapes 10 and 20 in order to deform the hooks 12 of the fastener tape 10 and/or the fibers 22 of the support tape 20 in order to secure them to each other.

(88) The treatment could also be performed without applying heat, applying only pressure, or indeed by applying only heat, in particular remotely, or indeed by any other appropriate treatment.

(89) Depending on the materials selected to form the fastener tape 10 and the support tape 20, and depending on treatment conditions (temperature, applied pressure, etc.), the treatment may correspond to any of the examples shown and described above, in particular with reference to FIGS. 7A to 7C, 8, and 9. The characteristics described with reference to those examples are therefore not repeated here.

(90) In order to avoid damaging hooks 12 present on the free portion 18 of the fastener tape 10, the method is nevertheless preferably performed in the manner described with reference to FIG. 8. In other words: the fastener tape 10 is made of a material that melts at a temperature T2 higher than the melting temperature T1 of the support tape 20. The self-gripping fastening F made between the two tapes 10 and 20 is treated by being subjected to an intermediate temperature that is higher than T1 but lower than T2, such that the fibers 22 melt, and coat the hooks 12 that have themselves remained intact.

(91) The resulting assembled structure 100F is shown in FIG. 12B. It has a first layer 51 constituted by the fastener tape 10 and comprising retention means for a self-gripping fastening (specifically the intact hooks 12 of the fastener tape 10), and a second layer 52 resulting from local deformation of the support tape 20, coating the retention means 12 over an assembly zone 55 corresponding to the treatment zone in order to hold them captive and secure said layers to each other.

(92) In a third step illustrated by the segment T3, the assembled structure 100F is cut along a direction Y that extends substantially transversely relative to the machine direction X, thereby forming a plurality of hook-carriers 100F for diapers.

(93) The hook-carrier 100F as obtained in this way is equivalent to the above-defined assembled structure 100F, of which it forms a fragment. It comprises: a fastener portion 74 (formed by the free portion 18 of the fastener tape 10) comprising a substantially plane base defined by two main faces, a front face and a rear face, and hooks 12 projecting from the front face of said base; a support portion 72 made of non-woven material (formed by the free portion 28 of the support tape) situated on the front side of the base and extending in a plane that intersects the hooks 12; and between the fastener portion and the support portion (in a plane intersecting both the non-woven material and the hooks), an assembly zone.

(94) FIGS. 13 to 16 show another particular application of the method of the present disclosure for fabricating an assembled structure comprising a base, in particular a sheet or a composite material, that is reinforced in the vicinity of the location of a hole.

(95) A sheet or tarpaulin often presents holes are to receive fastener means such as elastic straps, bungees, or the like.

(96) Such a sheet is generally reinforced in the neighborhood of such holes by generally annular hollow reinforcing inserts of the eyelet type. Such eyelets are conventionally fastened by clip-fastening, which results in local deformation of the sheet and thus in a loss of strength.

(97) In other applications, it is also necessary to make holes in composite elements in order to fasten them to a support, thereby running the risk of locally damaging or weakening said elements.

(98) The assembly method of the present disclosure constitutes an advantageous solution for solving this problem.

(99) FIG. 13 shows a first unit 10 in the form of a reinforcing insert and a second unit 20 formed by a sheet of fibers, a non-woven material in this example.

(100) The reinforcing insert 10 is for fastening to the sheet 20 at a location 26 for a hole, as shown diagrammatically in FIG. 13, in other words at a location 26 of the sheet 20 that already has a hole, or that is to have a hole made therein (which is more usual, and as described in the present example).

(101) In the example shown, the reinforcing insert 10 is generally cylindrical in shape about a main axis A, and it defines a central through bore 16.

(102) The reinforcing insert 10 has at least one junction surface 11a extending substantially orthogonally to the main axis A and having a field of grip elements 12 projecting therefrom and suitable for co-operating with fibers 22 of the sheet 20 in order to provide a self-gripping fastening F.

(103) In the example of FIG. 12, the junction surface 11a is an axial end face of the insert 10.

(104) More particular, the grip elements 12 are distributed over all of said end face 11a.

(105) The way the reinforcing insert 10 is assembled on the sheet 20 is shown in greater detail in FIGS. 14A to 14D.

(106) In a first step shown in FIGS. 14A and 14B, the reinforcing insert 10 is brought into contact with the sheet 20 so that the grip elements 12 that project from its junction surface 11a come to co-operate with the fibers 22 of the sheet 20 in order to make a self-gripping fastening F. The bore 16 is placed substantially in register with the location 26 for the hole.

(107) In a second step shown in FIG. 14C, the self-gripping fastening F is treated. Depending on the materials selected for forming the sheet 20 and the grip elements 12 of the reinforcing insert 10, and depending on treatment conditions (temperature, applied pressure, etc.), the treatment may correspond to any of the examples shown and described above, in particular with reference to FIGS. 7A to 7C, 8, and 9. The characteristics described with reference to those examples are therefore not repeated here.

(108) In this example, the hooks 12 of the insert 10 melt under the effect of the treatment and coat the fibers 22 of the sheet 20 that remain substantially intact. The assembled structure 100G comprising the sheet 20 reinforced by the reinforcing insert 10 is shown in FIG. 14C. It comprises a first layer 51 constituted by the sheet 20 with retention means for a self-gripping fastening (specifically the fibers 22), and a second layer resulting from deformation of the hooks 12 of the insert 10, which coat the retention means 22 in an assembly zone 55.

(109) Generally, in a third step shown in FIG. 14D, the sheet 20 is then pierced at the location 26 for the hole, substantially along the main axis of the reinforcing insert 10.

(110) The sheet 20 is thus reinforced in the neighborhood of its hole location 26 but without being damaged or deformed around the reinforcing insert 10. Furthermore, the insert 10 is fastened in reliable and permanent manner ensuring a long life for the assembly.

(111) Nevertheless, the example shown is not limiting.

(112) In FIG. 16, the insert 10 presents an external collar 17 at one of its axial ends that is referred to as its bottom end 10a, and its junction surface carrying the gripper elements 12 is the face 17a of said collar 17 that faces towards its top end 10b.

(113) As shown in the figure, the insert is then inserted through an orifice that has already been made in the sheet 20 so that said junction surface 17a is brought into contact with the sheet 20 in order to provide the self-gripping fastening F for securing the two units together.

(114) The method of the present disclosure may also be used for fabricating a composite material that is reinforced by at least one reinforcing insert.

(115) Under such circumstances, the initial steps of the method are substantially identical to those described with reference to FIGS. 13 and 14A to 14C.

(116) In order to form the composite element, in a step shown in FIG. 15A, the sheet 20 is associated with a third unit 30, specifically a resin. By way of example, the sheet is placed in a mold (not shown) presenting the shape that is desired or the composite element, and it is impregnated with the resin 30 inside the mold. The resin then forms the matrix of the composite, with the fibers 22 of the sheet 20 constituting its reinforcing means. The assembled structure 100H comprising the composite 90 reinforced by the reinforcing insert 10 is shown in FIG. 15A.

(117) The composite 90 as obtained in this way can then be pierced through the insert without risk of damage, as shown in FIG. 15B.

(118) In a variant, the second and third units 20 and 30 may also be assembled by performing the method of the present disclosure, in particular using the implementations described with reference to FIGS. 1 to 9.

(119) By way of example, a composite element reinforced by at least one insert at a location for a hole may be fabricated in a manner similar to the example of FIGS. 5A to 5C, the first unit being constituted by the insert 10, the second unit being constituted by the sheet 20, and the third unit 30 comprising a base with a field of grip elements adapted to co-operate with the fibers of the sheet 20.

(120) The first and second units form a first self-gripping fastening at the junction surface of the insert.

(121) The second and third units form a second self-gripping fastening that preferably extends over their entire area of contact.

(122) The first self-gripping fastening may be treated first, followed by the second, or vice versa. It is also possible for both self-gripping fastenings to be treated simultaneously.

(123) Finally, the second and third units form a composite element in which the reinforcing means are formed by the fibers of the sheet, which have remained intact. The first unit is secured to the composite element in order to reinforce it at the location of its hole.