Method for producing a blade for a suspension

Abstract

A method of manufacturing a blade (1) for a vehicle suspension, the blade (1) having a curved profile in a rest state and being made of a thermoplastic material, the method comprising: - a winding step in which an intermediate element (10) is produced by continuously winding a thermoplastic tape around a support; - a heating step in which the intermediate element (10) is positioned and then heated in a heating device; - a placing step in which the heated intermediate element (10') is placed in a forming mold (T1, T2); - a thermoforming step in which a second part (T1) of the forming mold (T1, T2) is closed onto a first part (T2) to obtain the sheet (1).

Description

[0001] The invention relates to the field of vehicle suspensions, in particular to wheel suspensions, and more particularly to a method for manufacturing a blade for a suspension and a blade manufactured by the manufacturing method. State of the art

[0002] The purpose of a vehicle suspension is to reduce the impact of deformations of a surface on which the vehicle travels, in terms of wear and comfort.

[0003] There is a suspension system described in FR3 037 865 that includes an elastic sheet having a resting state in which the sheet has a curved profile and a maximum extension state in which the sheet has an elongated profile. The elastic sheet is manufactured using a fiber composite material, with the fibers continuously wound around metal inserts. There is therefore a need for a process for producing the sheet that is fast, cost-effective and allows for recycling of the sheet. Disclosure of the invention

[0004] One embodiment relates to a method of manufacturing a blade for a vehicle suspension, the blade extending along a longitudinal axis between a first end and a second end, the blade being elastically deformable between a rest state in which the blade has a curved profile along the longitudinal axis and an extended state in which the first and second ends are spaced apart from each other with respect to the rest state, the blade being made of a thermoplastic material, the method implementing: - a winding step in which an intermediate element is produced by continuously winding a thermoplastic tape around a support so that the intermediate element has a closed contour delimiting at least one interior space, the tape being wound along a longitudinal direction of the tape; - a heating step in which the intermediate element is positioned and then heated in a heating device; - a placing step in which the heated intermediate element is placed in a first part of a forming mold such that a first end point and a second end point of the intermediate element, taken along a longitudinal axis of the intermediate element, are spaced apart by a distance equal to that separating the first and second ends of the sheet in the rest state; - a thermoforming step in which a second part of the forming mold is closed onto the first part to obtain the sheet.

[0005] The blade according to the invention is configured to be mounted in a vehicle suspension, for example, a wheel. To this end, the blade comprises at least a first attachment point positioned at the first end and a second attachment point positioned at the second end.

[0006] The leaf is elastically deformable between the resting state and the extended state. Thus, when the suspension is compressed between two points of the suspension attached to the two attachment points, the leaf is subjected to extension, with the two points of the suspension moving away from each other.

[0007] The blade is formed by a single-piece element which has a flexural rigidity, ie when the ends of the blade are stretched, which is very lower than its tensile rigidity, ie along its longitudinal axis.

[0008] In addition, the blade has a non-zero radius of curvature at rest. The radius of curvature can be constant, variable along the longitudinal axis, multiple (i.e., the blade has a wavy shape), or secondary profiles (i.e., small waves forming a larger wave).

[0009] The sheet is made of a thermoplastic material, meaning a material that softens when heated but hardens again upon cooling, while retaining the shape it had when warm. The thermoplastic material is recyclable.

[0010] In some embodiments, the thermoplastic material is a polymer.

[0011] The process includes a winding step. In this step, the thermoplastic tape is wound continuously along its longitudinal direction onto a carrier. The carrier has a shape identical to the shape of the intermediate element obtained by winding.

[0012] In some embodiments, the intermediate element extends along a longitudinal axis corresponding to a winding direction of the tape, ie, the longitudinal direction of the tape.

[0013] In some embodiments, the longitudinal axis of the intermediate member corresponds to the longitudinal axis of the blade.

[0014] The intermediate element has a closed contour that defines at least one interior space.

[0015] In some embodiments, the intermediate element has a convex shape along a section in a plane in which the longitudinal axis of the intermediate element extends.

[0016] In some embodiments, the intermediate member has only one interior space. The intermediate member includes a first endpoint and a second endpoint located at each of the ends of the intermediate member along its longitudinal axis.

[0017] In the heating step, the intermediate element is softened so that it can be deformed. The intermediate element is heated by a heating device, such as a furnace or heating tunnel.

[0018] The placement step consists of moving the hot intermediate element and placing it in the first part of the forming mold. In this mold, the intermediate element is positioned so that the distance between the first endpoint and the second endpoint is equal to the distance between the first end and the second end of the final sheet. In other words, the first endpoint and the second endpoint are fixed relative to the first part of the mold in the thermoforming step.

[0019] The thermoforming step consists in closing the second part of the mold onto the first part, which includes the intermediate element, in order to deform the intermediate element and obtain the desired sheet.

[0020] Thus, the manufacturing process enables a large production volume of recyclable sheet in a cost-effective manner.

[0021] The subject matter of the present disclosure may also comprise one or more of the following features alone or in combination.

[0022] In some embodiments, the thermoplastic tape comprises fibers extending in the longitudinal direction of the tape.

[0023] In some embodiments, the fibers are continuous fibers.

[0024] The belt is therefore a thermoplastic composite belt. The fibers are continuous fibers, which differ from short or long fibers, which are discontinuous.

[0025] The fibers extend along the longitudinal direction of the tape, so that when the tape is wound onto the carrier, the fibers are uninterrupted. Thus, the process maintains the mechanical strength properties of the fibers, which are preferably continuous.

[0026] In some embodiments, the thermoplastic tape is wound on itself in at least two layers during the winding step.

[0027] In some embodiments, the thermoplastic tape is wound on itself in a plurality of layers, e.g., between 5 and 50 layers.

[0028] Thus, it is possible to obtain a desired thickness for the final sheet, the thickness being measured along an axis perpendicular to the thermoplastic tape.

[0029] In some embodiments, the at least two layers of the thermoplastic tape are pressed and / or heated together by a roller.

[0030] The heating is carried out using a laser, for example.

[0031] The laser makes it possible to heat the layer of thermoplastic tape being wound locally and precisely in order to soften it and fix it to the lower layer.

[0032] The roller allows pressure to be applied to the thermoplastic tape to fix the thermoplastic tape being wound to the lower layer.

[0033] This holds the layers of the thermoplastic tape together.

[0034] In some embodiments, the intermediate element is removed from the carrier prior to the heating step.

[0035] The carrier is therefore not heated. Only the intermediate element is heated.

[0036] Thus, a first deformation of the intermediate element can be carried out in the heating step.

[0037] In some embodiments, the heating step moves the first endpoint and the second endpoint of the intermediate element away from each other.

[0038] In other words, in the heating step, a tension is exerted on the intermediate element along its longitudinal axis so that it is elongated.

[0039] In some embodiments, in the heating step, tension is applied to the first endpoint and the second endpoint.

[0040] The tension allows the fibers of the band to be held along the longitudinal axis of the intermediate element.

[0041] In some embodiments, the method further comprises a positioning step after the winding step in which at least one insert is positioned in the interior of the intermediate element.

[0042] The insert makes it possible to ensure a connection between the blade and the suspension when mounting the blade on the vehicle's suspension.

[0043] In some embodiments, the at least one insert is positioned prior to the heating step.

[0044] Thus, the at least one insert is at least partially held in the intermediate element during deformation. The positioning of the insert is thus final.

[0045] In some embodiments, the at least one insert is metal or plastic.

[0046] In some embodiments, a first insert is positioned at the first endpoint and a second insert is positioned at the second endpoint of the intermediate member.

[0047] In some embodiments, in the placement step, the intermediate element is deformed by means of a deformation device.

[0048] The deformation device applies pressure to the intermediate element to deform it prior to the thermoforming step. This deformation is intended to maintain the internal structure of the intermediate element, i.e., to align the fibers of the tape with the longitudinal axis of the intermediate element.

[0049] The deformation device can come into contact with the intermediate element or exert pressure from a distance, such as a negative pressure.

[0050] Another aspect of the invention relates to a blade for a vehicle suspension obtained by implementing a method according to the invention. Short description of the drawings

[0051] The invention will be better understood from the following description, which refers to several embodiments according to the present invention, given as non-limiting examples and explained with reference to the attached schematic drawings, in which: [ Fig. 1] is a schematic representation of an intermediate element according to the invention positioned in a furnace; [ Fig. 2] is a schematic representation of a heating step according to the invention; [ Fig. 3] is a schematic representation of a placement step according to the invention; [ Fig. 4] is a schematic representation of the placement step according to the invention; [ Fig. 5] is a schematic representation of the placement step according to the invention; [ Fig. 6] is a schematic representation of the placement step according to the invention; [ Fig. 7] is a schematic representation of the placement step according to the invention; [ Fig. 8] is a schematic representation of a thermoforming step according to the invention; [ Fig. 9] is a schematic representation of the thermoforming step according to the invention. Description of the embodiments

[0052] Only those elements necessary for understanding the invention have been shown. To facilitate reading of the drawings, the same elements bear the same reference numerals from one figure to the next.

[0053] The invention relates to a method for producing a sheet 1 for a vehicle suspension and a sheet 1 produced by such a method as in Fig. 9 is obtained.

[0054] The blade 1 extends along a longitudinal axis between a first end 3 and a second end 4. The blade 1 is formed by a single-piece element having a flexural rigidity, ie when the ends 3, 4 of the blade 1 are stretched, which is very lower than its tensile rigidity, ie along its longitudinal axis.

[0055] The blade 1 according to the invention is configured to be mounted in a vehicle suspension, for example, a wheel. To this end, the blade 1 comprises at least a first attachment point positioned at the first end 3 and a second attachment point positioned at the second end 4. In the embodiment illustrated in the figures, each attachment point is provided with an insert 2.

[0056] Sheet 1 is made of a thermoplastic material, i.e., a material that softens when heated but hardens again upon cooling, while retaining the shape it had when warm. This thermoplastic material is recyclable.

[0057] In some embodiments, the thermoplastic material is a polymer.

[0058] In a resting state, the blade 1 has a curved profile along the longitudinal axis, the radius of curvature of which can be constant, as in Fig. 9, be variable along the longitudinal axis, be multiple, ie the sheet has a wavy shape, or have secondary profiles, ie small waves forming a larger wave.

[0059] The blade 1 is elastically deformable between the rest state and an extended state in which the first 3 and second 4 ends are spaced apart from the rest state. Thus, upon compression of the suspension between two points of the suspension attached to the two attachment points of the blade 1, the blade 1 is subjected to extension, with the two suspension points moving away from each other.

[0060] The method according to the invention comprises in particular a winding step in which an intermediate element 10 is produced.

[0061] The intermediate element 10 extends along a longitudinal axis corresponding to the longitudinal axis of the final blade 1.

[0062] The intermediate element 10 has a closed contour that defines at least one interior space 11. In the figures, the intermediate element has only one interior space 11.

[0063] In some embodiments, the intermediate element 10 has a convex shape along a section in a plane in which the longitudinal axis of the intermediate element 10 extends.

[0064] The intermediate element 10 comprises a first end point 13 and a second end point 14, which are arranged at each of the ends of the intermediate element 10 along its longitudinal axis.

[0065] The intermediate element is obtained by continuously winding a thermoplastic tape around a support along a longitudinal direction of the tape. The support has a shape identical to a shape of the intermediate element 10 obtained by the winding.

[0066] In some embodiments, the intermediate element 10 extends along a longitudinal axis corresponding to a winding direction of the tape, ie, the longitudinal direction of the tape.

[0067] In some embodiments, the thermoplastic tape comprises fibers extending in the longitudinal direction of the tape. Preferably, the fibers are continuous fibers.

[0068] The tape is therefore a thermoplastic composite tape. The fibers can be carbon or glass fibers.

[0069] The fibers extend along the longitudinal direction of the tape, so that when the tape is wound onto the carrier, the fibers are uninterrupted. Thus, the process maintains the mechanical strength properties of the fibers.

[0070] The fibers thus also extend along the longitudinal axis of the intermediate element 10 and ultimately along the longitudinal axis of the sheet 1. In some embodiments, the thermoplastic tape is wound onto itself during the winding step in at least two layers, and preferably in a plurality of layers, e.g., between 5 and 50 layers. Thus, it is possible to obtain a desired thickness for the final sheet 1, the thickness being measured along an axis perpendicular to the thermoplastic tape.

[0071] In some embodiments, the at least two layers of the thermoplastic tape are pressed and / or heated together by a roller.

[0072] The heating is carried out using a laser, for example.

[0073] The laser makes it possible to heat the layer of thermoplastic tape being wound locally and precisely in order to soften it and fix it to the lower layer.

[0074] The roller allows pressure to be applied to the thermoplastic tape to fix the thermoplastic tape being wound to the lower layer.

[0075] This holds the layers of the thermoplastic tape together.

[0076] Then the intermediate element 10 is removed from the carrier.

[0077] The method then comprises a positioning step in which the at least one insert 2 is positioned in the interior space 11 of the intermediate element 10. More specifically, a first insert 2 is positioned at the first end point 13, and a second insert 2 is positioned at the second end point 14 of the intermediate element 10.

[0078] In some embodiments, the at least one insert 2 is metal or plastic.

[0079] Inserts 2 ensure a secure connection between the blade and the suspension when mounting the blade on the vehicle's suspension. The inserts serve as attachment points for the blade.

[0080] The method according to the invention then comprises a heating step in which the intermediate element 10 is positioned and then heated in a heating device, such as an oven or a heating tunnel, as in Fig. 1, is heated.

[0081] In the heating device, the intermediate element 10 is positioned on a support comprising an upper element F1 that is movable relative to a lower element F2. During operation of the furnace, the upper element F1 is positioned on the lower element F2.

[0082] The intermediate element 10 is positioned in the upper element F1. More specifically, the intermediate element 10 is held in the upper element F1 by retaining extensions inserted into the inserts 2.

[0083] In the heating step, the intermediate element 10 is softened so that it can be deformed. More specifically, as shown in Fig. 2, the first end point 13 and the second end point 14 of the intermediate element 10 are spaced apart from each other. In other words, during the heating step, tension is exerted by the holding extensions on the intermediate element 10 along its longitudinal axis, causing it to be elongated.

[0084] The heated intermediate element 10' is therefore deformed by the holding extension relative to the intermediate element 10. The inserts 2 are therefore at least partially held in the heated intermediate element 10'. The positioning of the inserts is thus final.

[0085] The tension makes it possible to hold the fibers of the thermoplastic tape along the longitudinal axis of the heated intermediate element 10'.

[0086] Then, the method comprises a placement step in which the heated intermediate element 10' is placed in a first part T2 of a forming mold T1, T2.

[0087] To achieve this, the upper element F1 of the support is separated from the lower element F2 and then positioned on the first part T2 of the forming mold T1, T2, as shown in the Fig. 3 and Fig. 4 shown.

[0088] Then the heated intermediate element 10' is moved along its longitudinal axis as shown in Fig. 5. The heated intermediate element 10' therefore always has the same shape, and the length between the inserts 2 has not been changed. This displacement allows the position of the support extensions to be changed relative to the upper element F1, allowing them to be subsequently brought closer together.

[0089] Then the holding extensions, which are always inserted into the inserts 2, are brought closer to each other and moved towards the first part T2 of the forming die T1, T2, as shown in Fig. 6. This shift, which is shown in Fig. 6, the heated intermediate element 10' is deformed into a deformed intermediate element 10".

[0090] After this displacement, the deformed intermediate element 10" is in contact with the first part T2 of the forming die T1, T2.

[0091] The first end point 13 and the second end point 14 of the deformed intermediate element 10" are spaced apart by a distance equal to that separating the first end 3 and the second end 4 of the blade 1 in the rest state.

[0092] The deformed intermediate element 10" has a deformation angle that is positioned substantially in the center of the deformed intermediate element 10".

[0093] In some embodiments, the heated intermediate element 10' is deformed by means of a deformation device that exerts pressure on the heated intermediate element 10'. This deformation is intended to maintain an internal structure of the heated intermediate element 10', i.e., an alignment of the fibers of the thermoplastic ribbon with the longitudinal axis of the intermediate element 10.

[0094] The deformation device can come into contact with the heated intermediate element 10' or exert pressure from a distance, such as a negative pressure.

[0095] When the deformed intermediate element 10" is in contact with the first part T2 of the forming mold T1, T2, the upper element F1 of the carrier can be removed, as in Fig. 7 shown.

[0096] The process then includes a thermoforming step, which is carried out in the Fig. 8 and Fig. 9, in which a second part T1 of the forming mold T1, T2 is closed onto the first part T2 and thus onto the deformed intermediate element 10" in order to obtain the desired sheet 1.

[0097] In the thermoforming step, the first end point 13 and the second end point 14 of the deformed intermediate element 10" are fixed with respect to the first part T2 of the forming mold T1, T2.

[0098] When the thermoforming step is completed, the forming mold T1, T2 is opened and the sheet 1 is pulled out.

[0099] Thus, the manufacturing process enables a large production volume of recyclable sheet in a cost-effective manner.

[0100] Although the present invention has been described with reference to specific 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 are to be considered in an illustrative and not a limiting sense.

[0101] It is also obvious that all features described with reference to a method are transferable, alone or in combination, to a device and, conversely, all features described with reference to a device are transferable, alone or in combination, to a method. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] FR 3 037 865

[0003]

Claims

A method for producing a sheet (1) for a vehicle suspension, the sheet (1) extending along a longitudinal axis between a first end (3) and a second end (4), the sheet (1) being elastically deformable between a rest state in which the sheet (1) has a curved profile along the longitudinal axis and an extended state in which the first (3) and second (4) ends are spaced apart from each other with respect to the rest state, the sheet (1) being made of a thermoplastic material, the method implementing: - a winding step in which an intermediate element (10) is produced by continuously winding a thermoplastic tape around a support such that the intermediate element (10) has a closed contour delimiting at least one internal space (11), the tape being wound along a longitudinal direction of the tape;- a heating step in which the intermediate element (10) is positioned and then heated in a heating device;- a placing step in which the heated intermediate element (10') is placed in a first part (T2) of a forming mold (T1, T2) so that a first end point (13) and a second end point (14) of the intermediate element (10), taken along a longitudinal axis of the intermediate element (10), are spaced apart by a distance equal to that separating the first (3) and second (4) ends of the sheet (1) in the rest state;- a thermoforming step in which a second part (T1) of the forming mold (T1, T2) is closed onto the first part (T2) to obtain the sheet (1); The method of claim 1, wherein the thermoplastic tape comprises fibers extending in the longitudinal direction of the tape. A method according to any one of the preceding claims, wherein the thermoplastic tape is wound on itself in at least two layers during the winding step. Method according to claim 3, wherein the at least two layers of the thermoplastic tape are pressed and / or heated onto one another by a roller. Method according to one of the preceding claims, wherein the intermediate element (10) is removed from the carrier before the heating step. Method according to one of the preceding claims, wherein in the heating step the first end point (13) and the second end point (14) of the intermediate element (10) are moved away from each other. Method according to one of the preceding claims, further comprising a positioning step after the winding step in which at least one insert (2) is positioned in the interior space (11) of the intermediate element (10). Method according to claim 7, wherein a first insert (2) is positioned at the first end point (13) and a second insert (2) is positioned at the second end point (14) of the intermediate element (10). Method according to one of the preceding claims, wherein in the placing step the intermediate element (10) is deformed by means of a deformation device. Blade (1) for a vehicle suspension obtained by implementing a method according to any one of the preceding claims.

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