Improved retention device

Abstract

The invention relates to a retention device (1), which comprises: - a base (10), extending in a main direction (MD); - a plurality of retention elements (20) extending from the upper face (12) of the base (10), the retention elements (20) each having a rod (30) and a head (40), the rod (30) having a front end and a rear end in the main direction, characterised in that the head (40) of each retention element (20) has two hooking portions (42) located on either side of the rod (30) in the transverse direction (CD), at least one of the hooking portions (42) having a concavity (46) and a border (44) at least partially defining a contour of the concavity (46).

Description

IMPROVED RETAINER DEVICE Description Technical Field

[0001] The present invention relates to improved retaining devices, and more particularly relates to retaining elements for producing a self-gripping system. Prior art

[0002] Restraint systems using hook-type retaining elements for the creation of self-gripping connections are commonly used in many fields. However, the production of retaining elements poses many problems, both in terms of design to meet the targeted requirements, and in terms of production.

[0003] The present invention thus aims to respond at least partially to these problems. Statement of the invention

[0004] The present invention thus provides a retaining device, comprising - a base, extending in a main direction, having an upper face and a lower face, the upper face forming a plane extending in the main direction and a transverse direction, perpendicular to the main direction, - a plurality of retaining elements extending from the upper face of the base, said retaining elements each having a rod and a head, the rod having a front end and a rear end in the main direction, characterized in that the head of each retaining element has two hooking portions located on either side of the rod in the transverse direction, each forming a radial protuberance relative to the rod, one of the attachment portions has a concavity and an edge defining at least partially a contour of the concavity.

[0005] According to one example, each attachment portion has a concavity and an edge at least partially defining a contour of the concavity, said concavities being disjoint.

[0006] According to one example, the concavity has a curvature which includes at least one inflection point, the component line which is perpendicular to the curvature of the concavity and passing through said at least one inflection point has a non-zero component in a transverse direction (CD) and / or in the main direction (MD). Thus, with such a concavity shape of the attachment portion, the retention capacity with a suitable counterpart, for example a loop counterpart, is increased and such a concavity makes it possible to increase the resistance of the attachment portion during stress with a suitable counterpart, for example a loop counterpart.

[0007] According to one example, the concavity has a curvature which comprises at least two inflection points, each straight line with a component respectively perpendicular to the curvature of the concavity and passing respectively through the at least two inflection points has a non-zero component in a transverse direction (CD) and / or in the main direction (MD). Thus, with such a concavity shape of the attachment portion, the retention capacity of a suitable counterpart, for example a counterpart with loops, is further increased and the concavity makes it possible to further increase the resistance of the attachment portion during stress with a suitable counterpart, for example a counterpart with loops.

[0008] According to one example, the concavity has a curvature that includes at least a plurality of inflection points forming an inflection line that extends in a direction including a first component extending along the main direction (MD) and a second component extending along the transverse direction (CD), the first and second components being non-zero. Thus, with such a concavity shape of the gripping portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such concavity also makes it possible to increase the resistance of the gripping portion during stress with a suitable counterpart, for example a counterpart with loops.

[0009] According to one example, the retaining element comprises two gripping portions each comprising a concavity, the inflection line of each of the concavities is convergent towards the front and / or towards the rear of the retaining element. Thus, the retaining element has, on one side, a preferred shape to facilitate the insertion of a counterpart, for example a counterpart with loops, and on the other, a preferred shape to retain the counterpart.

[0010] According to one example, the concavity of the gripping portion has a single or no trailing edge in the main direction (MD), which trailing edge may extend forward or rearward of the retaining element. Thus, with such a concavity shape of the gripping portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such a concavity also makes it possible to increase the strength of the gripping portion when stressed with a suitable counterpart, for example a counterpart with loops.

[0011] According to one example, the concavity of the gripping portion has no trailing edge in the transverse direction (CD). Thus, with such a concavity shape of the gripping portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such a concavity also makes it possible to increase the resistance of the gripping portion when stressed with a suitable counterpart, for example a counterpart with loops.

[0012] According to one example, each gripping portion has a concavity and an edge at least partially defining a contour of the concavity, said concavities being joined by the front or the rear of the retaining element.

[0013] According to one example, the concavity is arranged on a lateral part of the gripping portion, in particular a lateral part of the gripping portion oriented at least partly laterally and / or towards the front or rear of the retaining element. Thus, with a concavity arrangement of the gripping portion, the retention capacity with a suitable counterpart, for example a loop counterpart, is increased and such a concavity also makes it possible to increase the strength of the gripping portion when stressed with a suitable counterpart, for example a loop counterpart.

[0014] According to one example, the projection of the head on the upper face of the base is comprised between a front plane, perpendicular to the main direction and tangent to the front end of the rod, and a rear plane perpendicular to the main direction and tangent to the rear end of the rod. Thus, with such an arrangement of the head relative to the rod, the deformation capacity of the head and / or the rod is reduced during loading with a suitable counterpart, for example a counterpart of the loops and the insertion capacity of the counterpart, for example a counterpart of the loops, is improved. According to one example, one of the gripping portions has a concavity, and the concavity is a non-opening concavity, or the cavity is typically a blind cavity. Thus, with such a concavity shape, the retention of the suitable counterpart, for example a counterpart of the loops, is higher.

[0015] In one example, each hook portion has a concavity, and each concavity is a non-opening cavity, or each cavity is typically a blind cavity. Thus, with such a concavity shape, the retention of the adapted counterpart, for example a counterpart of the loops, is higher.

[0016] According to one example, one of the gripping portions has a concavity and an edge defining at least partially a contour of the concavity, an edge section arranged on the side opposite the base and extending substantially in a plane parallel to the base forms an edge section of the gripping portion most opposite the base.

[0017] According to one example, each attachment portion has a concavity and an edge defining at least partially a contour of the concavity, an edge section arranged on the side opposite the base and extending substantially in a plane parallel to the base forms an edge section of the attachment portion most opposite the base.

[0018] In the case where each attachment portion has a concavity, said concavities are typically discontinuous or disjointed.

[0019] According to one example, the head has a central portion positioned between the two attachment portions in the transverse direction, the central portion having a maximum height in a direction perpendicular to the upper face of the base strictly less than the maximum height of the attachment portions.

[0020] According to one example, the central portion of the head has a front end and a rear end along the main direction, and the central portion of the head has a height relative to the upper face of the base strictly greater than the rear end relative to the height at the front end. Thus, with such a difference in height, the insertion capacity of the counterpart, for example a counterpart with loops, is easier. According to one example, the rod has two lateral faces perpendicular to the transverse direction, each lateral face being planar, the two lateral faces being parallel or substantially parallel.

[0021] According to one example, each gripping portion defines an asperity on a face of the gripping portion opposite the concavity. This asperity has the advantage, in particular due to the position, of locally improving the retention of the fibers or filaments of the loop counterpart. Advantageously, the asperity is arranged on a face of the gripping portion opposite the concavity and in a manner centered in the transverse direction (CD) relative to the retaining element and / or between the two lateral gripping portions.

[0022] According to one example, the stem has a rectangular section, in particular a rectangular section with right or rounded angles, decreasing from the upper face of the base towards the head.

[0023] In one example, the stem has a square section, in particular a square section with right or rounded angles, decreasing from the upper face of the base towards the head.

[0024] According to one example, in a view parallel to the transverse direction (CD), the rod of the retaining element has a front edge and a rear edge, each of the front and rear edges having a curved (non-rectilinear) shape. More precisely, the portions of the front and rear edges arranged near the base are further apart than the portions of the front and rear edges arranged near half the height of the rod and / or the head. Thus, thanks to such a shape, the counterpart insertion is facilitated, in particular the counterpart can easily be inserted and / or guided below the head.

[0025] In one example, when viewed parallel to the main direction (MD), the stem of the retaining element has a left edge and a right edge, each of the left and right edges having a substantially rectilinear shape. More specifically, the portions of the left and right edges arranged proximate the base are rectilinear up to at least half the height of the stem.

[0026] According to one example, in a plane perpendicular to the main direction (MD) and passing through the concavity, the concavity has a curvature defined between two end points, the curvature has a circular arc or C or U shape and / or the second end point is offset from the plumb line passing through the first end point. Thus, with such an arrangement of the concavity, the deformation capacity of the head and / or the rod is reduced during loading with a suitable counterpart, for example a counterpart with loops and the insertion capacity of the suitable counterpart, for example a counterpart with loops, is easier.

[0027] According to one example, in any plane perpendicular to the main direction (MD) and passing through the concavity, the concavity having a curvature defined between two end points, said curvatures respectively have a shape of an arc of a circle or of a C or of a U and / or the second end point is offset from the plumb line passing through the first end point. Thus, with such an arrangement of the concavity, the deformation capacity of the head and / or the rod is reduced during a stress with a suitable counterpart, for example a counterpart with loops and the insertion capacity of the suitable counterpart, for example a counterpart with loops, is easier.

[0028] According to one example, in a plane perpendicular to the main direction (MD) and passing through the gripping portion, the upper edge and the lower edge of the gripping portion define two end points, the second end point of the gripping portion is offset from the plumb line passing through the first end point of the gripping portion. Thus, with such an arrangement of the concavity, the deformation capacity of the head and / or the rod is reduced during stress with a suitable counterpart, for example a counterpart with loops and the insertion capacity of the suitable counterpart, for example a counterpart with loops, is easier.

[0029] According to one example, in any plane perpendicular to the main direction (MD) and passing through the attachment portion (except for the ends of the attachment portion), the upper edge and the lower edge of the attachment portion in the vertical direction respectively define a first end point and a second end point, the second end point of the attachment portion being offset from the vertical line passing through the first end point of the attachment portion, typically outwardly relative to the rod. Thus, with such an arrangement of the concavity, the deformation capacity of the head and / or the rod is reduced during loading with a suitable counterpart, for example a counterpart with loops, and the insertion capacity of the suitable counterpart, for example a counterpart with loops, is easier.

[0030] According to one example, when viewed perpendicular to the plane comprising the main direction (MD) and the transverse direction (CD), the upper edge of the head of the retaining element has a curved shape, preferably a circular arc or "C" shape, the opening of which is arranged at the front or rear of the retaining element. Thus, thanks to such a shape, insertion is facilitated and the retention capacity is improved.

[0031] The present invention also relates to a method of forming a retaining device, wherein: - a base is formed, extending in a main direction, having an upper face and a lower face, the upper face forming a plane extending in the main direction and a transverse direction, perpendicular to the main direction, the base having a plurality of rods extending from its upper face, each rod having a front end and a rear end in the main direction, the base being supported by a drive element moving it from upstream to downstream, - a first forming step is carried out, in which thermoforming is carried out on the free end of the rod, so as to drive the material from the free end of the rod downstream, so as to form a preform comprising a radial projection extending at least partially downstream from the free end of the rod, - a second forming step is carried out, in which the material of the preform is folded from downstream to upstream, so that the downstream portion of the preform is folded over a central portion of the head, the forming steps being carried out so as to form two attachment portions located on either side of the rod in the transverse direction, each forming a radial protuberance relative to the rod, at least one of the attachment portions having a concavity and an edge forming / defining at least partially a contour of the concavity.

[0032] According to one example, the forming steps are carried out so that each attachment portion has a concavity and an edge defining at least at least partially a contour of the concavity, said concavities being disjoint.

[0033] According to one example, the forming steps are carried out so that the projection of the head on the upper face of the base is between a front plane, perpendicular to the main direction and tangent to the front end of the rod, and a rear plane perpendicular to the main direction and tangent to the rear end of the rod.

[0034] According to one example, the first forming step is carried out by means of an element having a curvature reversed with the curvature of the base of the retaining device, for example a roller, in particular a roller having a rotational and / or linear speed greater than or equal to a speed at which the base is driven by the driving element, and / or, in certain cases, strictly greater than a speed at which the base is driven by the driving element.

[0035] According to one example, the forming roller of the first stage has a diameter greater than or equal to 100 mm, in particular greater than or equal to 200 mm, and / or less than or equal to 1000 mm, in particular less than or equal to 450 mm.

[0036] According to one example, the second forming step is carried out by means of a second forming station, adapted to carry out heating of the preform.

[0037] According to one example, the second forming station comprises a roller, which roller has a diameter greater than or equal to 100 mm, in particular greater than or equal to 200 mm, and / or less than or equal to 1000 mm, in particular less than or equal to 450 mm.

[0038] In another example, the second forming station includes a convexing element, for example a fixed convexing element, having a curvature in the same direction as the curvature of the base of the retainer.

[0039] According to one example, the convexing element has a convexing distance (minimum gap) greater than or equal to 0.20 mm, in particular greater than or equal to 0.30 mm, in particular greater than or equal to 0.40 mm and / or less than or equal to 0.70 mm, in particular less than or equal to 0.60 mm.

[0040] According to a second aspect of the invention, taken independently and / or in common with the rest of the characteristics of the present description, the invention relates to a retaining device, comprising - a base, extending in a main direction, having an upper face and a lower face, the upper face forming a plane extending in the main direction and a transverse direction, perpendicular to the main direction, - a plurality of retaining elements extending from the upper face of the base, said retaining elements each having a rod and a head, the rod having a front end and a rear end in the main direction , in which the head has a central portion positioned between the two attachment portions in the transverse direction, the central portion having a maximum height strictly less than the maximum height of the attachment portions.

[0041] According to one example, for each retaining element, when viewed in the transverse direction, the head extends beyond the front end and / or the rear end of the rod in the main direction, thereby forming a front overhang and / or a rear overhang.

[0042] According to one example, the front end and / or the rear end of the rod in the main direction are those arranged in a portion of the rod near the head and / or in a portion of the rod near the base.

[0043] According to one example, for each retaining element, when viewed in the transverse direction, the head is devoid of a front overhang and includes a rear overhang or vice versa.

[0044] According to one example, the front overhang and / or the rear overhang of the rod is greater than or equal to 2%, and / or less than or equal to 20%, in particular less than or equal to 15% of the dimension of the rod in a direction parallel to the main direction and passing through the portion of the stem arranged near the head and / or passing through the portion of the stem near the base.

[0045] According to one example, for each retaining element, according to a view in the transverse direction, the head is devoid of a front overhang and / or a rear overhang.

[0046] According to one example, the head of the retaining element, in particular each head of the retaining elements, is symmetrical along a plane passing through the center of the rod and perpendicular to the transverse direction CD.

[0047] According to one example, the head of the retaining element, in particular each head of the retaining elements, is asymmetrical along a plane passing through the center of the rod and perpendicular to the main direction MD.

[0048] According to one example, in a view parallel to the main direction, the head forms at least one overhang of more than 10%, in particular more than 15%, in particular more than 20%, more particularly more than 40%, of the width of the rod at the upper end of the rod and / or the head forms at least one overhang of less than 90%, in particular less than 80%, in particular less than 70% of the width of the rod at the upper end of the rod.

[0049] According to one example, in a view along the main direction, the head forms at least two overhangs, each of the overhangs being more than 10%, in particular more than 15%, in particular more than 20%, more particularly more than 40%, of the width of the rod at the upper end of the rod and / or the head forms at least one overhang of less than 90%, in particular less than 80%, in particular less than 70% of the width of the rod at the upper end of the rod.

[0050] According to one example, the head of each retaining element has two gripping portions each forming a radial protuberance relative to the rod, in particular a radial protuberance relative to a portion of the rod arranged near the head and / or relative to a portion of the rod arranged near the base.

[0051] According to one example, the attachment portion, in particular each attachment portion of the retaining element, has an asymmetrical shape along any plane perpendicular to the main direction MD and / or along any plane perpendicular to the transverse direction CD.

[0052] According to one example, the heads of the retaining elements have, according to a view in the main direction, two left and right end portions whose surface forms, on average, an angle greater than or equal to 30° with the straight line parallel to the surface of the base and tangent to the head end arranged on the side of the base, in particular greater than or equal to 40°, in particular greater than or equal to 45°, and / or less than or equal to 80°, in particular less than or equal to 75°, in particular less than or equal to 65°.

[0053] In one example, the average is obtained by a series of at least 5 carryover elements.

[0054] According to one example, the central portion of the head has, according to a view in the main direction, in particular according to a front view, two plate portions parallel or substantially parallel to the upper face of the base which are separated by a central protuberance, for example in the shape of a dome and / or a point.

[0055] According to one example, the central portion of the head has, in a view parallel to the main direction, a central protuberance, for example in the shape of a dome and / or a point.

[0056] According to one example, the head of the retaining element has, in a view parallel to the main direction, a maximum dimension in a direction perpendicular to the upper face of the base which is arranged at the level of the attachment portion(s) and a minimum dimension arranged between the attachment portions.

[0057] The ratio, on average, of the maximum and minimum dimension of the head is between 1% and 30%, in particular between 5% and 25%, in particular between 7% and 22%. With such a ratio, the penetration of the elements of retention, particularly the head of the retaining element, in the loops is improved while retaining significant gripping capacity.

[0058] According to one example, when viewed in a direction perpendicular to the upper face of the base, the head has a general shape of an arc of a circle or of a V or of a C, the free ends of which are arranged at the front of the head or at the rear of the head.

[0059] According to one example, when viewed in the transverse direction CD, the head has a general shape of an arc of a circle or of a V or of a C, the free ends of which are arranged at the front of the head or at the back of the head, or the head has a general shape of a drop of water, the free end of which is arranged at the front of the head or at the back of the head.

[0060] According to one example, when viewed in the transverse direction CD, the head has a front portion and a rear portion, the front portion being different from the rear portion.

[0061] According to one example, when viewed in the transverse direction CD, the head has a front portion and a rear portion, the front portion has a generally rounded shape and the rear portion has a generally less rounded shape than the front portion, in particular a pointed shape, or vice versa.

[0062] According to one example, when viewed in the transverse direction CD, the concavity has a general shape of an arc of a circle or of a V or of a C, the free ends of which are arranged at the front of the head or at the back of the head, or the concavity has a general shape of a drop of water, the free end of which is arranged at the front of the head or at the back of the head, or the concavity has a general shape of a square or rectangle, the greatest length of the rectangle of which extends substantially parallel to the main direction MD.

[0063] According to one example, when viewed in the CD direction, the border has a general shape of an arc of a circle or of a V or of a C, the free ends of which are arranged at the front of the head or at the back of the head, or the border forms a contour having a general shape of a drop of water, the free end of which is arranged at the front of the head or at the back of the head, or the border forms an outline having the general shape of a square or rectangle, the greatest length of the rectangle of which extends substantially parallel to the main direction MD.

[0064] According to one example, when viewed in a direction perpendicular to the upper face of the base, the head has an angle to the left and / or to the right forming an angle of attack between a straight line tangent to the gripping portion and the transverse direction which is, on average, greater than or equal to 15°, in particular greater than or equal to 17°, in particular greater than or equal to 20°, and / or less than or equal to 35°, in particular less than or equal to 32°, in particular less than or equal to 30°, more particularly less than or equal to 28°.

[0065] According to one example, according to a view in a direction perpendicular to the upper face of the base, an angle formed between two straight lines connecting a rear end of the head 40 and the front ends of the attachment portions in the main direction is greater than or equal to 60°, in particular greater than or equal to 65°, in particular greater than or equal to 70°, and / or less than or equal to 120°, in particular less than or equal to 105°, in particular less than or equal to 95°, more particularly less than or equal to 28°.

[0066] According to one example, the head has, in a view parallel to the transverse direction, a cone portion shape whose smallest opening is turned towards the center of the head.

[0067] According to one example, one of the attachment portions forming a radial protuberance relative to the rod has a lower edge oriented towards the base and an upper edge opposite the base, the projection of the lower edge and the upper edge in a plane parallel to the face of the base has a continuous shape, for example the shape of a curve, in particular the general shape of a C and / or a U and / or a V whose opening is for example oriented towards the rear end of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V.

[0068] According to one example, one of the gripping portions forming a radial protrusion relative to the rod has a lower edge oriented towards the base and a upper edge opposite the base, the projection of the lower edge and the upper edge in a plane perpendicular to the main direction has a continuous shape, for example the shape of a curve, in particular the general shape of a C and / or a U and / or a V whose opening is for example oriented towards the center of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V.

[0069] According to one example, one of the attachment portions forming a radial protuberance relative to the rod has a lower edge oriented towards the base and an upper edge opposite the base, the projection of the lower edge and the upper edge in a plane perpendicular to the transverse direction has a continuous shape, for example the shape of a curve, in particular the general shape of a C and / or a U and / or a V whose opening is for example oriented towards the rear of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V.

[0070] According to one example, the base has, on its upper face, continuous or substantially continuous ribs extending in the main direction. According to one example, one rib, two, three or four ribs extend between two rows of retaining elements. In some cases, at least one rib extends at the foot of each retaining element.

[0071] According to one example, the retaining elements have a height, in a direction perpendicular to the longitudinal axis, which is greater than or equal to 200 micrometers, in particular greater than or equal to 250 micrometers, in particular greater than or equal to 300 micrometers, and / or less than or equal to 700 micrometers, in particular less than or equal to 600 micrometers, in particular less than or equal to 550 micrometers.

[0072] According to one example, the retaining elements and / or the base are made of a material based on a thermoplastic material, for example - a polyolefin, in particular a polypropylene (PP) and / or a polyethylene (PE), in particular a bio-sourced polyethylene (Bio-PE) and / or their copolymers, and / or - a polyester, in particular a polyethylene terephthalate (PET), for example a bio-sourced polyethylene terephthalate (Bio-PET), and / or a biodegradable polyester and / or a Polyhydroxyalkanoate (PHA) and / or a poly-lactic acid (PLA) and / or a polybutylene adipate terephthalate (PBAT) and / or a Polybutylene succinate (PBS) and / or a poly(butylene succinate co-butylene adipate) (PBS A) and / or a Poly (Polybutylene succinate) (PES) and / or a poly(trimethylene succinate) (PTS) and / or a poly(tetramethylene adipate-co-terephthalate) (PTAT) and / or a Polycaprolactone (PCL) and / or a Thermoplastic Starch (TPS), and / or - a polyamide (PA) in particular a bio-sourced polyamide (Bio-PA), and / or a casein derivative and / or - a mixture of two or more of these thermoplastic materials. Brief description of the drawings

[0073] The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples.

[0074] [Fig. 1] Figure 1 is a view of an example of retaining devices according to one aspect of the invention.

[0075] [Fig. 2] Figure 2 is a perspective view of an exemplary retaining element.

[0076] [Fig. 3] Figure 3 is a view of an example of a retaining element.

[0077] [Fig. 4] Figure 4 is another view of an example of a retaining element.

[0078] [Fig. 5] Figure 5 is another view of an example of a retaining element.

[0079] [Fig. 6] Figure 6 is another view of an example of a retaining element.

[0080] [Fig. 7] Figure 7 is a schematic representation of part of an apparatus which may be used for the production of such a retaining element.

[0081] Throughout the figures, common elements are identified by identical numerical references. Description of the embodiments

[0082] An example of a retaining device according to one aspect of the invention is described below, as shown in Figure 1, and detailed partial views of which are presented in Figures 2 to 6. According to one example, Figures 1 to 6 are figures to scale where the “pitch” (distance between two retaining elements) of the same column in the main direction MD is between 0.53 mm and 0.55 mm, preferably approximately 0.54 mm, and / or the height of the retaining element is between 0.40 mm and 0.34 mm, preferably approximately 0.37 mm. In these figures in particular, it is possible to directly deduce other characteristics, in particular dimensional characteristics.

[0083] In this presentation, the measurements taken are typically obtained by taking an average of 5 measurements, where appropriate on 5 separate retaining elements.

[0084] The figures show a retaining device 1 comprising a base 10 and a plurality of retaining elements 20.

[0085] The base 10 forms a ribbon extending in a main direction MD or machine direction. The base has an upper face 12 and a lower face 14, said faces being typically flat or substantially flat along a plane defined by the main direction MD and a transverse direction CD perpendicular to the main direction MD. The vertical direction is defined by the direction perpendicular to the plane defined by the main direction MD and the transverse direction CD, in a direction going from the lower face 14 towards the upper face 12.

[0086] The thickness of the base 10 is defined as the distance between the upper face 12 and the lower face 14, typically the average distance between the upper face 12 and the lower face 14.

[0087] The retaining elements 14 extend from the upper face 12 of the base 10, and are typically formed as a single piece, integral with the base 10.

[0088] The retaining elements 14 typically have a height, in a direction perpendicular to the upper face 12 of the base 10, which is greater than or equal to 200 micrometers, in particular greater than or equal to 250 micrometers, in particular greater than or equal to 300 micrometers, and / or less than or equal to 700 micrometers, in particular less than or equal to 600 micrometers, in particular less than or equal to 550 micrometers.

[0089] According to one example, the retaining elements 14 and / or the base 10 are made of a material based on a thermoplastic material, for example - a polyolefin, in particular a polypropylene (PP) and / or a polyethylene (PE), in particular a bio-sourced polyethylene (Bio-PE) and / or their copolymers, and / or - a polyester, in particular a polyethylene terephthalate (PET), for example a bio-sourced polyethylene terephthalate (Bio-PET), and / or a biodegradable polyester and / or a Polyhydroxyalkanoate (PHA) and / or a poly-lactic acid (PLA) and / or a polybutylene adipate terephthalate (PBAT) and / or a Polybutylene succinate (PBS) and / or a poly(butylene succinate co-butylene adipate) (PBS A) and / or a Poly (Polybutylene succinate) (PES) and / or a poly(trimethylene succinate) (PTS) and / or a poly(tetramethylene adipate-co-terephthalate) (PTAT) and / or a Polycaprolactone (PCL) and / or a Thermoplastic starch (TPS), and / or - a polyamide (PA) in particular a bio-sourced polyamide (Bio-PA), and / or a casein derivative and / or - a mixture of two or more of these thermoplastic materials.

[0090] In the illustrated example, the device has several rows of retaining elements 20, each row extending in the main direction MD, the different rows therefore being typically parallel to each other. Such an embodiment is not limiting, the retaining elements 20 can be arranged in any pattern and any configuration on the base 10, in particular in a staggered pattern.

[0091] According to one example, the base 10 has, on its upper face 12, continuous or substantially continuous ribs 16 extending in the main direction MD. According to one example, one rib, two, three or four ribs extend between two rows of retaining elements 20. In certain cases, at least one rib extends at the foot of each retaining element 20.

[0092] The retaining elements 20 each have a rod 30 and a head 40.

[0093] The rod 30 extends from the upper face 12 of the base 10 to a free end where the head 40 is located. A front end and a rear end are arbitrarily defined for the rod 30 in the main direction MD. In the description, reference may be made to the front and rear ends of the various elements, in particular the retaining elements 20 and the head 40 of the retaining elements 20 according to this same arbitrary designation. A front plane PA and a rear plane PR are defined, perpendicular to the upper face 12 of the base 10, and tangent respectively to the front end and to the rear end of the rod 30.

[0094] In the illustrated example, the rod 30 has a rectangular section, with rounded corners, and decreasing from the upper face 12 of the base to the free end of the rod 30. In the illustrated example, the rod 30 has two parallel lateral faces 32 and 34, said lateral faces forming the ends of the rod 30 in the transverse direction CD.

[0095] In the illustrated example, the rod 30 has a front face 36 and a rear face 38 along the main direction MD, the front and rear designations being arbitrary here and mentioned solely for illustration purposes.

[0096] In the illustrated example, the front face 36 and the rear face 38 tend to move closer together from the upper face 12 of the base to the free end of the rod 30. Thus, the thickness of the rod 30 along the main direction MD typically decreases from the upper face 12 of the base to the free end of the rod 30. By decreasing section, it is meant here that the surface of the section of the head 30 decreases from the upper face 12 of the base 10 towards the head 40. According to one example, the decrease may be continuous or discontinuous.

[0097] The head 40 is formed so as to have a section of dimension greater than the dimension of the section of the free end of the rod 30. Thus, the head extends radially beyond the rod 30, so as to form zones of gripping for a counterpart, typically loops or other retaining elements.

[0098] In the example illustrated, the head 40 has two attachment portions 42 each forming a radial protuberance relative to the rod 30. The attachment portions 42 as shown extend on either side of the rod in the transverse direction CD.

[0099] The attachment portions 42 are typically formed so as to, in projection along a plane parallel to the upper face 12 of the base 10, form two portions inclined at an angle of between 30 and 60° relative to the main direction MD, and forming for example a V shape or a circular arc whose apex is oriented towards the rear end along the main direction MD. Figure 6 shows angles A1 and A2.

[0100] The angle Al designates, in projection onto the upper face 12 of the base 10, the angle formed between a straight line tangent to a rear inclined portion of each attachment portion 42 and the transverse direction CD. This angle Al is typically greater than or equal to 15°, in particular greater than or equal to 17°, in particular greater than or equal to 20°, and / or less than or equal to 35°, in particular less than or equal to 32°, in particular less than or equal to 30°, more particularly less than or equal to 28°. Thus, with such an angle, the counterpart, for example with loops, has a greater capacity to slide from the rear zone of the retaining element 14 towards the front zone of the retaining element 14.

[0101] The angle A2 designates the angle formed between two straight lines, each straight line connecting, in projection on the upper face 12 of the base 10 and considering the longitudinal direction, a rear end of the head 40 and a front end of the head 40. The angle A2 is typically greater than or equal to 60°, in particular greater than or equal to 35°, in particular greater than or equal to 70°, and / or less than 120°, in particular less than or equal to 105°, in particular less than or equal to 95°. Thus, with such an angle, the counterpart, for example with loops, has a greater capacity to slide from the rear zone of the retaining element towards the front zone of the retaining element to facilitate retention.

[0102] According to one example, according to a view in the transverse direction CD, the head 40 has a general shape of an arc of a circle or of a V or of a C or of a U whose free ends are arranged at the front of the head or at the rear of the head or the head has a general shape of a drop of water whose free end is arranged at the front of the head 40 or at the rear of the head 40.

[0103] According to one example, when viewed in the transverse direction CD, the head 40 has a front portion and a rear portion, the front portion being different from the rear portion.

[0104] According to one example, when viewed in the transverse direction CD, the head 40 has a front portion and a rear portion, the front portion has a generally rounded shape and the rear portion has a generally less rounded shape than the front portion, in particular a pointed shape, or vice versa.

[0105] At least one of the attachment portions 42, or typically each attachment portion 42, has an edge 44 forming one end of the attachment portion 42 along the transverse direction CD. The edge 44 at least partially forms a contour, typically open and having two ends located at the same end or close to the same front or rear end of the head 40, typically at the rear end or close to the rear end of the head 40. According to one example, an edge section 44 arranged on the side opposite the base 10 and extending substantially in a plane parallel to the base 10 forms an edge section 44 of the attachment portion 42 most opposite the base 10.

[0106] According to one example, the edge 44 forms a contour having a C or U or V shape, the opening of which is for example oriented towards the rear end of the retaining element 20. The edge is shown diagrammatically by dotted lines in the figures.

[0107] According to one example, according to a view in the transverse direction CD, the concavity 46 has a general shape of an arc of a circle or of a V or of a C whose free ends are arranged at the front of the head 40 or at the rear of the head 40 or even the concavity 46 has a general shape of a drop of water whose the free end is arranged at the front of the head 40 or at the rear of the head 40 or the concavity 46 has a general shape of a square or rectangle of which the greatest length of the rectangle extends substantially parallel to the main direction MD.

[0108] According to one example, according to a view in the direction CD, the edge 44 has a general shape of an arc of a circle or of a V or of a C or of a U, the free ends of which are arranged at the front of the head 40 or at the rear of the head 40, or the edge 44 forms a contour having a general shape of a drop of water, the free end of which is arranged at the front of the head 40 or at the rear of the head 40, or the edge 44 forms a contour having a general shape of a square or rectangle, the greatest length of the rectangle of which extends substantially parallel to the main direction MD.

[0109] According to one example, one of the attachment portions 42 forming a radial protuberance relative to the rod 30 has a lower edge oriented towards the base 10 and an upper edge opposite the base 10, the projection of the lower edge and the upper edge in a plane parallel to the upper face 12 of the base 10 has a continuous shape, for example the shape of a curve, in particular the general shape of a C or a U or a U whose opening is for example oriented towards the rear end of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V.

[0110] According to one example, one of the attachment portions 42 forming a radial protuberance relative to the rod 30 has a lower edge oriented towards the base 10 and an upper edge opposite the base 10, the projection of the lower edge and the upper edge in a plane perpendicular to the main direction MD has a continuous shape, for example the shape of a curve, in particular the general shape of a C and / or a U and / or a V whose opening is for example oriented towards the center of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V. [011 ljAccording to one example, one of the attachment portions 42 forming a radial protuberance relative to the rod 30 has a lower edge oriented towards the base 10 and an upper edge opposite the base 10, the projection of the lower edge and the edge upper in a plane perpendicular to the transverse direction CD has a continuous shape, for example the shape of a curve, in particular the general shape of a C and / or a U and / or a V whose opening is for example oriented towards the rear of the retaining element, more particularly the general shape of a crushed C and / or a crushed U and / or a crushed V.

[0112] Border 44 can also form a closed contour.

[0113] For each attachment portion 42, the edge 44 is typically formed on a portion forming an inclined face, oriented in a direction having a component in the main direction MD, in the transverse direction CD and in the non-zero vertical direction.

[0114] Figure 5 shows an angle A3, which represents, according to a view in a plane perpendicular to the main direction MD, an angle formed between a straight line tangent to an inclined face of a gripping portion 42 and the transverse direction CD. This angle A3 is typically greater than 30°, in particular greater than or equal to 40°, in particular greater than or equal to 45°, and / or less than or equal to 80°, in particular less than or equal to 75°, in particular less than or equal to 65°.

[0115] The edge 44 surrounds a concave portion or concavity 46 formed in the inclined face of each gripping portion 42. The angle A3 makes it possible in particular to define an orientation of the concavity 46, in a direction normal to the plane defined by the straight line tangent to the inclined face of the gripping portion 42 comprising the concavity 46. In the example illustrated, it can thus be seen that the concavity 46 is oriented in a direction having a non-zero component in the vertical direction, and a non-zero component in the transverse direction. In other words, the concavity 46 is at least partially oriented upwards, that is to say that it is oriented in a direction opposite to the base 10.

[0116] The concavity 46 is typically a non-opening or blind concavity. Thus, in the case where each attachment portion 42 comprises a concavity, these two concavities 46 are disjoint, and are in particular separated by a central portion 50 which will be described later.

[0117] The concavity 46 typically has a curvature which includes at least one inflection point, the component line which is perpendicular to the curvature of the concavity and passing through said at least one inflection point has a non-zero component in a transverse direction (CD) and / or in the main direction (MD). Thus, with such a concavity shape of the attachment portion, the retention capacity with a suitable counterpart, for example a loop counterpart, is increased and such a concavity makes it possible to increase the resistance of the attachment portion during stress with a suitable counterpart, for example a loop counterpart.

[0118] Alternatively, the concavity typically has a curvature that includes at least two inflection points, each straight line with a component respectively perpendicular to the curvature of the concavity and passing respectively through the at least two inflection points has a non-zero component in a transverse direction (CD) and / or in the main direction (MD). Thus, with such a concavity shape of the attachment portion, the retention capacity of a suitable counterpart, for example a counterpart with loops, is further increased and the concavity makes it possible to further increase the resistance of the attachment portion during stress with a suitable counterpart, for example a counterpart with loops.

[0119] Alternatively, the concavity 46 has a curvature which comprises at least a plurality of inflection points forming an inflection line which extends in a direction comprising a first component extending in the main direction (MD) and a second component extending in the transverse direction (CD), the first and second components being non-zero. 6 schematically represents the inflection lines 47 for the two concavities 46 illustrated. Thus, with such a concavity shape of the attachment portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such a concavity also makes it possible to increase the resistance of the attachment portion during stress with a suitable counterpart, for example a counterpart with loops.

[0120] According to one example, the retaining element 20 comprises two attachment portions each comprising a concavity 46, the inflection line of each of the concavities 46 is convergent towards the front and / or towards the rear of the retaining element. Thus, the retaining element 20 has, on one side, a preferred shape to facilitate the insertion of a counterpart, for example a counterpart with loops, and on the other, a preferred shape to retain the counterpart.

[0121] According to one example, the concavity 46 of the gripping portion has a single or no trailing edge in the main direction (MD), which trailing edge can extend forward or rearward of the retaining element 20. Thus, with such a concavity shape of the gripping portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such a concavity also makes it possible to increase the resistance of the gripping portion when stressed with a suitable counterpart, for example a counterpart with loops.

[0122] According to one example, the concavity 46 of the gripping portion has no trailing edge in the transverse direction (CD). Thus, with such a concavity shape of the gripping portion, the retention capacity with a suitable counterpart, for example a counterpart with loops, is increased and such a concavity also makes it possible to increase the resistance of the gripping portion during stress with a suitable counterpart, for example a counterpart with loops.

[0123] According to one example, the concavity 46 is arranged on a lateral portion of the gripping portion, in particular a lateral portion of the gripping portion oriented at least partly laterally and / or towards the front or rear of the retaining element. Thus, with a concavity arrangement 46 of the gripping portion, the retention capacity with a suitable counterpart, for example a loop counterpart, is increased and such a concavity also makes it possible to increase the strength of the gripping portion during stress with a suitable counterpart, for example a loop counterpart.

[0124] The head 40 has a central portion 50, located in the extension of the rod 30, between the attachment portions 42. The central portion 50 has a front end and a rear end in the main direction MD.

[0125] In the example illustrated, the height at the rear end of the central portion 50 is strictly greater than the height at the front end of the central portion 50, the height being measured relative to the upper face 12 of the base 10

[0126] According to one example, considering a view in a plane perpendicular to the main direction MD, the head 40 has a maximum dimension and a minimum dimension, measured along the height direction, perpendicular to the upper face 12 of the base 10. The maximum dimension is typically located at the level of the attachment portions 42. The minimum dimension is typically located between the attachment portions 42, in the central portion 50 of the head 40. The ratio, on average, of this maximum dimension and this minimum dimension of the head 40 is typically greater than or equal to 1%, in particular greater than or equal to 5%, in particular greater than or equal to 7%, and / or less than or equal to 30%, in particular less than or equal to 25%, in particular less than or equal to 22%. With such a ratio, the penetration of the retaining elements, in particular the head 40 of the retaining element, into loops is improved while retaining a significant attachment capacity.

[0127] The rear end of the central portion 50 of the head 40 may typically have a protrusion 52, oriented rearwardly in the main direction MD, and typically oriented upwardly in height.

[0128] The central portion 50 of the head 40 typically has a maximum height less than the maximum height of the attachment portions 42.

[0129] The central portion 50 of the head 40 typically has a recess or a concavity in the extension of the rod 30, which may for example result from a displacement of the material following the second forming step alone and / or the succession of the first forming step and the second forming step. forming a shrinkage or shrinkage of the material after formation of the retaining element 20.

[0130] The junction between the gripping portions 42 and the central portion 50 of the head 40 typically forms an asperity 48 on a face of each gripping portion 42 opposite the concavity 46. The asperities 48 are typically sized to allow the passage of a loop or filament of a counterpart, so as to allow engagement between the retaining elements 40 and loops or filaments. The asperities 48 as shown are formed between each gripping portion 42 and the central portion 50 of the head 40.

[0131] According to one example, the head 40 is formed so that a projection of the head 40 on the upper face of the base 10 is between the front plane PA and the rear plane PR. Such a configuration of the head relative to the rod makes it possible to reduce the deformation capacity of the head and / or the rod during stress with a suitable counterpart, for example a counterpart of the loops, and thus to improve the insertion capacity of the counterpart, for example a counterpart of the loops.

[0132] According to another example as shown on other retaining elements of FIG. 1, the central portion of the head 40 has, according to a view in the main direction, in particular according to a view in a forward-facing direction, two plate portions parallel or substantially parallel to the upper face of the base which are separated by a central protuberance, for example in the shape of a dome and / or a point.

[0133] According to one example, for each retaining element 14, according to a view in the transverse direction CD, the head 40 extends beyond the front end and / or the rear end of the rod 30 in the main direction MD, thus forming a front overhang and / or a rear overhang.

[0134] According to one example, the front end and / or the rear end of the rod 30 along the main direction MD are those arranged in a portion of the rod 30 near the head 40 and / or in a portion of the stem 30 near the base 10.

[0135] According to one example, for each retaining element 14, according to a view in the transverse direction, the head 40 is devoid of a front overhang and comprises a rear overhang or vice versa.

[0136] According to one example, the front overhang and / or the rear overhang is greater than or equal to 2%, and / or less than or equal to 20%, in particular less than or equal to 15% of the dimension of the rod 30 in a direction parallel to the main direction MD and passing through the portion of the rod 30 arranged near the head 40 and / or passing through the portion of the rod 30 near the base 10.

[0137] According to one example, for each retaining element 14, according to a view along the transverse direction CD, the head 40 is devoid of a front overhang and / or a rear overhang.

[0138] According to one example, according to a view parallel to the main direction MD, the head 40 forms at least one overhang of more than 10%, in particular more than 15%, in particular more than 20%, more particularly more than 40%, of the width of the rod 30 at the upper end of the rod 30 and / or the head 40 forms at least one overhang of less than 90%, in particular less than 80%, in particular less than 70% of the width of the rod 30 at the upper end of the rod 30.

[0139] According to one example, according to a view along the main direction, the head 40 forms at least two overhangs, each of the overhangs being equal to or more than 10%, in particular equal to or more than 15%, in particular equal to or more than 20%, more particularly equal to or more than 40%, of the width of the rod 30 at the upper end of the rod 30 and / or the head 40 forms at least one overhang equal to or less than 90%, in particular equal to or less than 80%, in particular equal to or less than 70% of the width of the rod 30 at the upper end of the rod 30.

[0140] An example of apparatus for producing such retaining elements is then presented with reference to Figure 7.

[0141] This figure shows part of an apparatus for forming a retaining device. The direction of movement or rotation of the different elements is symbolized by arrows.

[0142] The portion of the apparatus illustrated focuses on the formation of the head 40 of the retaining elements 20. Here, it is considered that the base 10 from which the rods 30 extend has been formed upstream. Reference will subsequently be made to upstream and downstream in relation to the direction of movement of the product on the apparatus.

[0143] As shown schematically in the figure, the base 10 is formed with rods 30, but is typically devoid of heads of the retaining elements 20. The rods 30 may also be topped with preforms or precursors of the heads. The base 10 is driven by a drive element 72 such as a roller.

[0144] A first forming station 74, typically comprising a forming roller, performs a thermoforming operation of the free end of the rods 30 or, where appropriate, the preforms or precursors. This thermoforming operation is typically performed at a rotational and / or linear speed greater than or equal to, or, in certain cases, strictly greater than, a drive speed of the strip 10 by the drive element 72. The first forming station 74 typically comprises a forming roller driven in rotation in a direction of rotation tending to move the material from the free end of the rods 30 or, where appropriate, the preforms or precursors downstream.

[0145] This forming step here typically forms a flat or substantially flat head preform 40, extending radially relative to the free end of the rod 30, and at least partially downstream.

[0146] A second forming station 76 is then positioned downstream of the first forming station 74.

[0147] The second forming station 76 is configured to perform a folding or convexing of the head preform produced by the first forming station 74. More specifically, the second forming station 76 is configured so as to cause the preform to fold back on itself from downstream to upstream. Thus, the downstream portion of the preform of the head will fold back at least in part onto the central portion of the head. This material folding effect will in particular form the two gripping portions 42, and will define the contour formed by the edge 44 as described previously.

[0148] The second forming station 76 may for example comprise a second forming roller driven in rotation in a direction opposite to the direction of movement of the product. The second forming station 76 typically raises the temperature of the preform of the head 40, in order to allow or facilitate the folding of material.

[0149] The second forming station 76 is arranged to apply a temperature greater than or equal to the deformation temperature under load (HDT) of the material used, for example 5°C greater than the deformation temperature under load (HDT) of the material used, or 10°C greater than the deformation temperature under load (HDT) of the material used, in particular 20°C greater, in particular 25°C greater, more particularly 30°C greater, and / or lower than a temperature corresponding to the deformation temperature under load (HDT) of the material used + 70°C, in particular lower than a temperature corresponding to the deformation temperature under load (HDT) of the material used + 60°C, in particular lower than a temperature corresponding to the deformation temperature under load (HDT) of the material used + 55°C,more precisely lower than a temperature corresponding to the deformation temperature under load (HDT) of the material used + 50°C, or even more precisely lower than a temperature corresponding to the deformation temperature under load (HDT) of the material used + 40°C. The second forming station 76 is arranged to apply a temperature lower than the melting temperature of the material used, in particular lower than 10°C than the melting temperature of the material used. These temperatures are typically used for a speed greater than 5 m / min and less than 130 m / min, in certain cases, less than 25 m / min. Thus, the material is folded on itself without heating, completely the material and soften it until it becomes fluid. Thus, processability is better controlled, the energy required to produce the retaining elements is lower, in particular the energy required to heat the retaining elements and the manufacturing speeds of such retaining elements are improved.

[0150] The device as proposed has improved properties compared to conventional retaining devices. In particular, the proposed retaining elements 20 make it possible to achieve a denser arrangement and to obtain a less abrasive and less rough product. The structure of the head 40 also makes it possible to improve the engagement of counterparts such as loops or fibers, and to improve the mechanical strength of the head 40, which therefore improves both the performance and the robustness of the product.

[0151] According to one example, the number of retaining elements 20 is between 50 and 450 retaining elements per cm 2 , in particular between 50 and 170 retaining elements per cm 2 , or in other cases between 200 and 350 retaining elements per cm 2 .

[0152] According to one example, the assembly formed by the base 10 and the plurality of retaining elements 20 has a weight typically greater than or equal to 45 g / m 2 , in particular greater than or equal to 70 g / m 2 , and / or less than or equal to 250 g / m 2 .

[0153] According to one example, the base 10 has a thickness, in a direction perpendicular to the face carrying the retaining elements, greater than 30 micrometers, in particular greater than or equal to 50 micrometers, and / or less than or equal to 200 micrometers, in particular less than or equal to 150 micrometers.

[0154] According to one example, considering the portions of the base 10 provided with retaining elements 14 and therefore not taking into consideration any areas of the base 10 devoid of retaining elements, a projection of the retaining elements 14 onto an external surface of the base 10 covers at least 5% of the external surface of the base, in particular at least 7% of the external surface of the base, in particular at least 10% of the external surface of the base, more particularly at least 15% of the external surface of the base, preferably at least 17% of the external surface of the base and / or at most 45% of the external surface of the base, in particular at most 40% of the external surface of the base, in particular at most 35% of the external surface of the base. Generally, for an object preceded by the words "for each" or "of each", it is understood that a majority of these objects according to the invention, for example at least 50%, 60%, 70%, 80%, 90%, 100% of these objects, includes such a characteristic.

[0155] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0156] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. A retaining device (1), comprising - a base (10), extending in a main direction (MD), having an upper face (12) and a lower face (14), the upper face (12) forming a plane extending in the main direction (MD) and a transverse direction (CD), perpendicular to the main direction (MD), - a plurality of retaining elements (20) extending from the upper face (12) of the base (10), said retaining elements (20) each having a rod (30) and a head (40), the rod (30) having a front end and a rear end in the main direction (MD) characterized in that the head (40) of each retaining element (20) has two attachment portions (42) located on either side of the rod (30) in the transverse direction (CD), each forming a radial protuberance relative to the rod (30) at least one of the attachment portions (42) having a concavity (46) and an edge (44) defining at least partially a contour of the concavity (46).

2. A retaining device (1) according to claim 1, wherein each gripping portion (42) has a concavity (46) and an edge (44) at least partially defining a contour of the concavity (46), said concavities (46) being disjointed.

3. A retaining device (1) according to claim 2, wherein the concavity (46) has a curvature which comprises at least one inflection point, such that a component line which is perpendicular to the curvature of the concavity and passing through said at least one inflection point has a non-zero component in a transverse direction (CD) and / or in the main direction (MD).

4. A retaining device (1) according to one of claims 2 or 3, wherein the concavity (46) is arranged on a lateral portion of the gripping portion (42), in particular a lateral part of the gripping portion oriented at least partly laterally and / or towards the front or rear of the retaining element (1).

5. Retaining device (1) according to one of claims 1 to 4, in which in any plane perpendicular to the main direction (MD) and passing through the attachment portion (42), an upper edge and a lower edge of the attachment portion (42) in a vertical direction perpendicular to the base (10) respectively define a first end point and a second end point, the second end point of the attachment portion (42) being offset outwards relative to the rod (30) of the plumb line passing through the first end point of the attachment portion.

6. Retaining device (1) according to one of claims 1 to 5, in which the projection of the head (40) on the upper face (12) of the base (10) is between a front plane, perpendicular to the main direction (MD) and tangent to the front end of the rod (30), and a rear plane perpendicular to the main direction (MD) and tangent to the rear end of the rod (30).

7. Retaining device (1) according to one of claims 1 to 6, in which the head (40) has a central portion (50) positioned between the two attachment portions (42) in the transverse direction (CD), the central portion (50) having a maximum height in a direction perpendicular to the upper face (12) of the base (10) strictly less than the maximum height of the attachment portions (42).

8. A retaining device (1) according to claim 7, wherein the central portion (50) of the head (40) has a front end and a rear end in the main direction, and wherein the central portion (50) of the head has a rear end and a front end, such that the height at the rear end is strictly greater than the height at the front end, the height being measured relative to the upper face (12) of the base (10).

9. Retaining device (1) according to one of the preceding claims, in which the rod (30) has two lateral faces (32, 34), each lateral face (32, 34) being planar, the two lateral faces (32, 34) being parallel and extending in a direction parallel to the main direction (MD) or to the transverse direction (CD).

10. Retaining device (1) according to one of the preceding claims, in which each gripping portion (42) defines an asperity (48) on a face of the gripping portion opposite the concavity (46).

11. Retaining device (1) according to one of the preceding claims, in which the rod (30) has a rectangular or square section, in particular a rectangular or square section with rounded or right angles, decreasing from the upper face (12) of the base (10) towards the head (40).

12. A method of forming a retaining device (1), wherein: - a base (10) is formed, extending in a main direction (MD), having an upper face (12) and a lower face (14), the upper face (12) forming a plane extending in the main direction (MD) and a transverse direction (CD), perpendicular to the main direction (MD), the base (10) having a plurality of rods (30) extending from its upper face (12), each rod (30) having a front end and a rear end in the main direction (MD), the base (10) being supported by a drive element (72) moving it from upstream to downstream, - a first forming step is carried out, in which thermoforming is carried out on the free end of the rod (30), so as to drive the material from the free end of the rod (30) downstream, so as to form a preform comprising a radial projection extending at least partially downstream from the free end of the rod (30), - a second forming step is carried out, in which the material of the preform is folded from downstream to upstream, so that the downstream portion of the preform is folded over a central portion (50) of the head (30), the forming steps being carried out so as to form a head (40) at the free end of the rod (30), comprising two attachment portions (42) located on either side of the rod (30) in the transverse direction (CD), each forming a radial protuberance relative to the rod (30), at least one of the attachment portions (42) having a concavity (46) and an edge (44) at least partially defining a contour of the concavity (46).

13. A method according to claim 12, wherein the forming steps are performed such that each gripping portion (42) has a concavity (46) and an edge (44) at least partially defining a contour of the concavity (46), said concavities (46) being disjointed.

14. Method according to one of claims 12 or 13, in which the forming steps are carried out in such a way that a projection of the head (40) on the upper face (12) of the base (10) is comprised between a front plane, perpendicular to the main direction (MD) and tangent to the front end of the rod (30), and a rear plane perpendicular to the main direction (MD) and tangent to the rear end of the rod (30).

15. Method according to one of claims 12 to 14, in which the first forming step is carried out by means of a roller (74) having a rotational and / or linear speed greater than or equal to a driving speed of the base (10) by the driving element (72), and in which the second forming step is carried out by means of a second forming station, adapted to carry out heating of the preform.

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