Optimized process for manufacturing an airless tire using additive manufacturing

Abstract

Additive manufacturing process for a casing 24 intended for the production of an airless tire 1, said additive manufacturing process employing an additive manufacturing machine 20 producing, in any XY plane perpendicular to the axis of rotation of said casing 24, several layers of the structural elements 25 of said casing 24 by depositing beads of a fusible printing material, the bead being continuous for each structural element 25 and said bead having, in any XY plane, a portion interpenetrating with the bead of each adjacent structural element 25. Figure for the abbreviation: Fig. 3

Description

Title of the invention: Optimized method for manufacturing an airless tire by additive manufacturing

[0001] The present invention relates to the field of manufacturing processes for airless tires intended to equip a vehicle.

[0002] The present invention relates more particularly to additive manufacturing processes using three-dimensional printing machines to manufacture airless tires by depositing a malleable printing material in successive layers, by means of a nozzle.

[0003] A printing machine generally comprises a chamber forming an enclosure delimited by a wall, and inside which is a platform for supporting a part being printed, as well as a nozzle for delivering the material constituting said part. To generate the shape of the part, drive systems are provided, including a lift for moving either the platform or the nozzle vertically, and cross-sliding tables for horizontally guiding either the platform or the nozzle responsible for delivering the material constituting the part.

[0004] Such printing machines are described in particular by US document 6,722,872.

[0005] An airless tire, or more generally a tire without inflation gas, is a tire that carries the load thanks to structural elements, constituting a carcass, and which has performance comparable to that of a conventional tire subjected to the internal pressure of a gas, generally air. An airless tire, mounted on a hub or rim, is sometimes called a "non-pneumatic elastic wheel".

[0006] In what follows, the circumferential or longitudinal direction designates the direction of rotation of the tire, the axial or transverse direction designates the direction parallel to the axis of rotation of the tire and the radial direction designates a direction perpendicular to the axis of rotation of the tire.

[0007] An airless tire generally comprises, radially from the inside out: -a carcass, made up of structural elements, designed to cooperate with a rim or hub, -a tread, intended to cooperate with the carcass and to transmit rolling forces to said carcass, to be worn and to guarantee the grip of the tire on a ground.

[0008] The frame comprises, radially from the inside out: -a load-bearing structure, designed to structurally support at least part of the load, -a shear strip, intended to transmit rolling forces to the supporting structure by shear and to contribute at least in part to the load-bearing capacity.

[0009] The load-bearing structure generally comprises, radially from the inside out: -a radially internal membrane intended to be fixed by means of connection to a rim or hub, -a connecting structure, intended to be fixed by means of connection to the inner radial membrane and the shear band. However, the supporting structure does not generally define a sealed internal cavity intended to contain a pressurized gas, as in a conventional tire. Consequently, an airless tire does not need to have a sealed connection to a rim or hub.

[0010] The shear strip comprises, in a known embodiment, radially from the inside to the outside: - a radially intermediate membrane, interfacing with the bonding structure, - a junction structure, -a radially outer membrane, intended to receive the tread and connected to the radially intermediate membrane by the junction structure.

[0011] Generally, the tread is fixed to the outer radial membrane of the shear strip by fastening means which may be, for example, gluing or shrink-fitting means.

[0012] The frame therefore comprises a plurality of elements called structural elements which may include, for example, a radially inner membrane, a plurality of radii, a radially intermediate membrane, a plurality of shear elements and a radially outer membrane.

[0013] Manufacturing processes for airless tire casings, well known to those skilled in the art, consist of first manufacturing the various structural elements independently before assembling them together in a second step, following a precise assembly and positioning procedure. The various structural elements can be held in position using different methods such as, for example, bonding, riveting, bolting, crimping, or ultrasonic welding.

[0014] Such methods for assembling an airless tire have been described, by way of example, in documents US20220194129A1, WO2008 / 136099A1, US9908369B2.

[0015] While such processes make it possible to manufacture airless tire carcasses, they nevertheless have disadvantages, related in particular to the weak adhesion between the different elements that constitute this carcass.

[0016] Furthermore, the manufacturing quality of such carcasses intended for the production of airless tires is not always satisfactory, the variations in geometric dimensions linked to the manufacture of each of the structural elements adding to the variations in positioning of the assembly process, which can therefore impair the overall quality of the airless tire and its performance.

[0017] Moreover, the assembly processes are quite complex and require numerous interventions to position the various structural elements, which generates high manufacturing costs.

[0018] Other methods for manufacturing airless tire casings, using molding processes to produce the various structural elements, are also known to those skilled in the art. These methods have been described, for example, in document JP 2022034665A.

[0019] These manufacturing processes for structural elements by molding require the manufacture of expensive tooling such as molds and do not allow the realization of complex geometries sometimes necessary for the manufacture of structural elements of a carcass of an airless tire.

[0020] The invention therefore aims to remedy the aforementioned drawbacks and to propose a manufacturing process which allows the simple and low-cost production of a carcass for an airless tire, which can use materials from a wide range, while guaranteeing excellent manufacturing reproducibility and perfect adhesion between the different structural elements of the carcass of the airless tire.

[0021] The invention essentially relates to an additive manufacturing process for the casing of an airless tire for a vehicle, employing an additive manufacturing machine comprising a manufacturing platform, perpendicular to the axis of revolution of the casing having an axial direction Z, and a nozzle, capable of moving along the axial direction Z and in any circumferential plane XY perpendicular to the axial direction Z, said additive manufacturing process comprising the following successive steps: (a) manufacturing a first layer of said frame, extending along the axial direction Z, by depositing a printing material onto the build platform by said nozzle, to form, in any order, beads as follows: -a radially internal membrane cord, intended for the manufacture of a radially internal membrane of the carcass and having a first width, -a radially intermediate membrane cord, intended for the manufacture of a - a radially intermediate membrane of the carcass and having a second width, - a radially external membrane cord, intended for the manufacture of a radially external membrane of the carcass and having a third width, - a connecting structure cord, intended for the manufacture of a connecting structure linking the radially internal membrane to the radially intermediate membrane, via a plurality of connecting portions, said connecting structure cord having a fourth width, and said connecting structure cord having a plurality of first zones interpenetrating with said radially internal membrane cord, each of said first interpenetrating zones having a first arc length and, along a radial direction, a first maximum thickness, said connecting structure cord also having a plurality of second zones interpenetrating with said radially intermediate membrane cord,each of said second interpenetrating zones having a second arc length and, along a radial direction, a second maximum thickness, , - a junction structure cord, intended for the fabrication of a junction structure linking the radially intermediate membrane to the radially outer membrane via a plurality of junction portions, said junction structure cord having a fifth width, and said junction structure cord having a plurality of third interpenetrating zones with said radially intermediate membrane cord, each of said third interpenetrating zones having a third arc length and, along a radial direction, a third maximum thickness, said junction structure cord also having a plurality of fourth interpenetrating zones with said radially outer membrane cord, each of said fourth interpenetrating zones having a fourth arc length and, along a radial direction, a fourth maximum thickness, (b) realization of at least one additional layer following step (a),the weld beads of at least one additional layer being superimposed along the axial direction Z on the weld beads of the axially adjacent preceding layer with remelting of the interface between the preceding layer and at least one additional layer.

[0022] Essentially, the additive manufacturing process according to the invention makes it possible to obtain a carcass for an airless tire by implementing a single process of depositing a printing material in the form of beads exiting a nozzle and without having to assemble several parts together to constitute said carcass. Each structural element of the carcass is thus constituted by an axial superposition of layers, each layer being made up of a single bead or "single cord", said "single cord" allowing to save time and quality of manufacture of the carcass of the airless tire, while improving the mechanical resistance of said carcass.

[0023] Consequently, the additive manufacturing process of the invention makes it possible to eliminate the assembly process of the various structural elements necessary for the manufacture of a carcass of an airless tire, which allows for a saving of manufacturing time and an improvement in the quality of the production of the carcass of the airless tire.

[0024] In addition, the additive manufacturing process according to the invention results in a lower manufacturing cost of the frame, as no tooling is required to manufacture the various structural elements.

[0025] Thanks to the interpenetration of the material beads deposited by the nozzle of the additive manufacturing machine in the bonding areas of the different structural elements, the adhesion between said different structural elements is improved, thus allowing better mechanical resistance and / or fatigue limit properties of the frame to be obtained.

[0026] Advantageously, the first width, the second width, the third width, the fourth width and the fifth width are equal to each other, thus reducing the time required to prepare the model of the carcass and saving production time.

[0027] Advantageously, the first width, second width, third width, fourth width and fifth width are respectively at least equal to 0.15mm and at most equal to 4mm and preferably at least equal to 0.4mm and at most equal to 2mm, such dimensional ranges allowing the object to be manufactured with standard nozzle diameters and existing additive manufacturing machine parameter settings.

[0028] Even more advantageously, the first maximum thickness, the second maximum thickness, the third maximum thickness and the fourth maximum thickness are equal to each other, thus reducing the time required to prepare the model of the carcass and saving production time.

[0029] Advantageously, the first maximum thickness is at least equal to 2% and at most equal to 20% of the smallest of the first and fourth widths, preferably at least equal to 5% and at most equal to 10% of the smallest of the first and fourth widths.

[0030] Advantageously, the second maximum thickness is at least equal to 2% and at most equal to 20% of the smallest of the second and fourth widths, preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fourth widths.

[0031] Advantageously, the third maximum thickness is at least equal to 2% and at most equal to 20% of the smaller of the second and fifth widths, preferably at least equal to 5% and at most equal to 10% of the smaller of the second and fifth widths.

[0032] Advantageously, the maximum fourth thickness is at least equal to 2% and at most equal to 20% of the smallest of the third and fifth widths, preferably at least equal to 5% and at most equal to 10% of the smallest of the third and fifth widths.

[0033] The intervals defined previously for the first, second, third and fourth thicknesses allow the interpenetration of successive layers to be maximized without introducing excess material which would accumulate and lead to manufacturing defects, or even the stopping and degradation of the machine.

[0034] Advantageously, the first arc length is at least equal to 3 times and at most equal to 150 times the smallest of the first and fourth widths, preferably at least equal to 10 times and at most equal to 60 times the smallest of the first and fourth widths.

[0035] Advantageously, the second arc length is at least equal to 3 times and at most equal to 150 times the smallest of the second and fourth widths, preferably at least equal to 10 times and at most equal to 60 times the smallest of the second and fourth widths.

[0036] Even more advantageously, the third arc length is at least equal to 3 times and at most equal to 150 times the smallest of the second and fifth widths, preferably at least equal to 10 times and at most equal to 60 times the smallest of the second and fifth widths.

[0037] Even more advantageously, the fourth arc length is at least equal to 3 times and at most equal to 150 times the smallest of the third and fifth widths, preferably at least equal to 10 times and at most equal to 60 times the smallest of the third and fifth widths.

[0038] The intervals defined previously for the first, second, third and fourth arc lengths make it possible to obtain sufficient adhesion between the structural elements without increasing the rigidity and mass of the wheel.

[0039] Preferably, the plurality of connecting portions comprises at least two connecting portions of different patterns, each of the connecting portions of different pattern being distributed circumferentially according to a constant pitch.

[0040] Preferably, the plurality of junction portions includes at least two junction portions of different patterns, each of the junction portions of different pattern being distributed circumferentially according to a constant pitch.

[0041] The distribution according to a constant pitch of the at least two connecting portions of different pattern and of the at least two junction portions of different pattern makes it possible to obtain a carcass whose mechanical operation, in particular under an imposed radial force, is identical over the entire circumference of the airless tire.

[0042] Preferably, the printing material is a polyaryletherketone (PAEK) thermoplastic, a polyetheretherketone (PEEK) thermoplastic, an aliphatic polyamide (PA), a polyetherimide (PEI), a polyimide (PI), a glycol-based polyester (PETG), or a thermoplastic elastomeric copolyester (TPC-ET). An example of a polyaryletherketone (PAEK) is Victrex™'s AM 200® product. An example of a thermoplastic elastomeric copolyester (TPC-ET) is DuPont™'s Hytrel® product.

[0043] Advantageously, the printing material has a melting temperature of at least 180°C and at most 450°C, allowing on the one hand sufficient thermal resistance in operation for low-demand uses, and on the other hand good malleability during the manufacture of the casing of the invention.

[0044] Advantageously, the printing material is different between at least two types of cords among the cords respectively of radially inner membrane, radially intermediate membrane, radially outer membrane, bonding structure and junction structure, thus allowing the rigidity or flexibility to be specified for each of the structural elements.

[0045] The invention also relates to a carcass made according to the manufacturing process according to the invention, and an airless tire comprising such a carcass.

[0046] Other objects, features and advantages of the invention will become apparent in more detail from the following description, as well as from the accompanying drawings, which are provided for illustrative purposes only and are not intended to be limiting: - [Fig.l]: Overview and perspective view of an airless tire comprising a carcass produced by the additive manufacturing process according to the invention. - [Fig.2]: Overview of an additive manufacturing machine used for the implementation of the process of the invention. - [Fig.3]: Overview and top view of the first layer deposited on the manufacturing platform of the airless tire carcass. - [Fig.4]: Axial and partial cross-sectional view of an airless tire made according to the process of the invention. - [Fig.5]: Circumferential and partial cross-sectional view of an airless tire carcass made according to the process of the invention. - [Fig.6]: Circumferential cross-sectional view of the first interpenetration zone. - [Fig.7]: Circumferential cross-sectional view of the second interpenetration zone. - [Fig.8]: Circumferential cross-sectional view of the third and fourth interpenetration zones.

[0047] In what follows, for the sake of clarity, the horizontal and vertical directions correspond to the natural orientation of Figures 1 to 7. Similarly, the terms "up", "down", "lower", "upper" and their variants should be understood with reference to to the vertical direction of the figures.

[0048] As can be seen in [Fig. 1], an airless tire 1 comprises, radially from the inside out: -a carcass 24 intended to cooperate with a rim or hub 4, -a tread 2, intended to cooperate with the carcass 24.

[0049] The frame 24 comprises, radially from the inside out: -a load-bearing structure 9, designed to cooperate with the rim or hub 4, -a shear strip 3, intended to cooperate with the tread 2.

[0050] The load-bearing structure 9 comprises, radially from the inside out: -a radially internal membrane 7 intended to be fixed by means of connection to the rim or hub 4, -a linking structure 28 intended to connect the radially inner membrane 7 and the shear strip 3.

[0051] The means for connecting the radially inner membrane 7 to the rim or hub 4 may be, by way of example, means of bonding, riveting, bolting or shrink-fitting.

[0052] The shear strip 3 comprises, in a known embodiment, radially from the inside to the outside: -a radially intermediate membrane 10, interfacing with the bonding structure, -a junction structure 29, -an outer radial membrane 5, intended to receive the tread 2 and connected to the intermediate radial membrane 10 by the junction structure 29.

[0053] The tread 2 can be fixed to the radially outer membrane 5 of the shear strip 3 by fastening means which may be, by way of example, gluing or shrink-fitting means.

[0054] The carcass 24 is thus made up of structural elements 25 comprising the radially inner membrane 7, the linking structure 28, the radially intermediate membrane 10, the junction structure 29 and the radially outer membrane 5.

[0055] The present invention relates to a method for producing the carcass 24 of an airless tire 1 using an additive manufacturing machine 20.

[0056] Figure 2 is an overview of an example of an additive manufacturing machine 20 implementation to carry out the process according to the invention. The additive manufacturing machine 20 comprises a nozzle 12, a build platform 14, a horizontal movement system 22 in any circumferential plane XY, and a vertical movement system 23 along an axial direction Z, perpendicular to any circumferential plane XY.

[0057] The horizontal movement system 22 and the vertical movement system 23 allow a relative movement of the nozzle 12 with respect to the build platform 14 to be controlled so that said nozzle 12 can deposit a molten printing material 21 in the form of preferably continuous beads 13.

[0058] Any other type of additive manufacturing machine by deposition of a bead 13 of a malleable printing material 21 is suitable, such as, for example, machines in which the relative movement of the nozzle 12 with respect to the build platform 14 is achieved by the movement of said build platform 14.

[0059] According to a first step of the process of the invention, a first layer of said frame 24, extending along the axial direction Z, will be made by depositing a printing material 21 on the manufacturing platform 14 by the nozzle 12, to form, in any order, cords Cl, C2, C3, C4, C5.

[0060] As can be seen in Figures 3 and 5, nozzle 12 will deposit: -a radially internal membrane cord Cl, intended for the manufacture of the radially internal membrane 7 of the carcass 24 and having a first width RI, -a radially intermediate membrane cord C2, intended for the manufacture of the radially intermediate membrane 10 of the carcass 24 and having a second width R2, -a radially external membrane cord C3, intended for the manufacture of the radially external membrane 5 of the carcass 24 and having a third width R3, -a C4 bonding structure cord, intended for the fabrication of a bonding structure 28 connecting the radially inner membrane 7 to the radially intermediate membrane 10, via a plurality of bonding portions 26, said C4 bonding structure cord having a fourth width R4, -a junction structure cord C5, intended for the manufacture of a junction structure 29 linking the radially intermediate membrane 10 to the radially external membrane 5 via a plurality of junction portions 27, said junction structure cord C5 having a fifth width R5.

[0061] As illustrated in [Fig.6], the bonding structure cord C4 has a plurality of first interpenetrating zones ZI with the radially inner membrane cord Cl, said first interpenetrating zones ZI each having a first arc length L1 and, along a radial direction, a first maximum thickness El.

[0062] As shown in [Fig.7], the structural cord C4 also has a plurality of second interpenetrating zones Z2 with the radially intermediate membrane cord C2, said second interpenetrating zones Z2 each having a second arc length L2 and, along a radial direction, a second maximum thickness E2.

[0063] As can be seen in [Fig.8], the junction structure cord C5 has a plurality of third interpenetrating zones Z3 with the radially intermediate membrane cord C2, said third interpenetrating zones Z3 each having a third arc length L3 and, along a radial direction, a third maximum thickness E3.

[0064] As can still be seen in [Fig.8], the junction structure cord C5 also has a plurality of fourth interpenetrating zones Z4 with the radially external membrane cord C3, said fourth interpenetrating zones Z4 each having a fourth arc length L4 and, along a radial direction, a fourth maximum thickness E4.

[0065] According to the process of the invention, the nozzle 12 will then produce at least one additional layer following step (a), the (Cl, C2, C3, C4, C5) beads of the at least one additional layer being superimposed in an axial direction Z on the (Cl, C2, C3, C4, C5) beads of the previous axially adjacent layer with remelting of the interface between the previous layer and the at least one additional layer.

[0066] As can be seen in [Fig.4], repeating step (a) will allow a one-piece carcass 24 to be produced, with a height H along the axial direction Z. The height H of the carcass 24 will obviously be adapted to the type of airless tire 1 to be produced and in particular, said height H will be adjusted to the width of the tread 2 of the airless tire 1.

[0067] Remelting the interface between two adjacent layers allows for a very strong bond between each layer, thus enabling the manufacture of monobloc 24 frames with high mechanical strengths.

[0068] The creation of interpenetration zones Z1, Z2, Z3 and Z4 during the deposition of the printing material 21 allows, on the one hand, the bonding structure 28 to adhere perfectly to the radially inner membrane 7 and to the radially intermediate membrane 10, and on the other hand, the junction structure 29 to adhere also perfectly to the radially intermediate membrane 10 and to the radially outer membrane 5.

[0069] This perfect adhesion between the structural elements 25 of the frame 24 makes it possible to obtain very high mechanical resistance and very good fatigue resistance of said frame 24 during stresses in operation.

[0070] Preferably, during the manufacturing of a layer of the carcass 24, the nozzle 12 starts the deposition of a layer of the radially inner membrane cord Cl, which is a cord delimiting a closed area, at a starting point which is different from the starting point of the previous layer, in order to obtain junction areas located at different horizontal azimuths between two adjacent layers.

[0071] Similarly, the deposition of a layer of the other cords C2, C3, each of which limiting a closed area, is also preferably done with different starting and ending points of the nozzle 12 from the previous layer, also allowing to obtain junction areas, between the beginnings and ends of beads, located according to different horizontal azimuths.

[0072] Obtaining, for each of the layers of the carcass 24, junction zones located along different horizontal azimuths for the cords delimiting closed zones makes it possible to strengthen the mechanical resistance of the carcass 24 by preventing the propagation of possible cracks in said junction zones.

[0073] In a particular embodiment, and as illustrated in [Fig.5], the first width RI, the second width R2, the third width R3, the fourth width R4 and the fifth width R5 are equal to each other and are respectively at least equal to 0.15 mm and at most equal to 4 mm, preferably at least equal to 4 mm and at most equal to 2 mm.

[0074] In another embodiment, it is possible to optimize the resistance of each of the structural elements 25 by adapting the widths RI, R2, R3, R4 and R5 of said structural elements 25. Indeed, each of the structural elements 25 of the frame 24 having a different shape and stress, it is possible to determine as precisely as possible each of the widths RI, R2, R3, R4 and R5.

[0075] These differences in thickness also make it possible to reduce the weight of the carcass 24, and to save on the amount of material deposited and on manufacturing time.

[0076] Preferably, and as can be seen in [Fig.5], the first maximum thickness El, the second maximum thickness E2, the third maximum thickness E3 and the fourth maximum thickness E4 are equal to each other.

[0077] Advantageously, the first maximum thickness El is at least equal to 2% and at most equal to 20% of the smallest of the first and fourth widths RI, R4, preferably at least equal to 5% and at most equal to 10% of the smallest of the first and fourth widths RI, R4.

[0078] Advantageously, the second maximum thickness E2 is at least equal to 2% and at most equal to 20% of the smallest of the second and fourth widths R2, R4, preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fourth widths R2, R4.

[0079] Even more advantageously, the third maximum thickness E3 is at least equal to 2% and at most equal to 20% of the smallest of the second and fifth widths R2, R5, preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fifth widths R2, R5.

[0080] Advantageously, the fourth maximum thickness E4 is at least equal to 2% and at most equal to 20% of the smallest of the third and fifth widths R3, R5, preferably at least equal to 5% and at most equal to 10% of the smallest of the third and fifth widths R3, R5.

[0081] Advantageously, the first arc length L1 is at least equal to 3 times and at most equal to 150 times the smallest of the first and fourth widths RI, R4, preferably at least equal to 10 times and at most equal to 60 times the smallest of the first and fourth widths RI, R4.

[0082] Even more advantageously, the second arc length L2 is at least equal to 3 times and at most equal to 150 times the smallest of the second and fourth widths R2, R4, preferably at least equal to 10 times and at most equal to 60 times the smallest of the second and fourth widths R2, R4.

[0083] Advantageously, the third arc length L3 is at least equal to 3 times and at most equal to 150 times the smallest of the second and fifth widths R2, R5, preferably at least equal to 10 times and at most equal to 60 times the smallest of the second and fifth widths R2, R5.

[0084] Even more advantageously, the fourth arc length L4 is at least equal to 3 times and at most equal to 150 times the smallest of the third and fifth widths R3, R5, preferably at least equal to 10 times and at most equal to 60 times the smallest of the third and fifth widths R3, R5.

[0085] As can be seen in [Fig. 5], in the interpenetrating zones Z1, Z2, Z3, Z4, the weld bead of a structural element 25 of the frame 24 is tangent to the weld bead of the adjacent structural element 25. This tangency allows the structural elements 25 to have geometries adapted to the types of stresses experienced by the frame 24, thus improving the mechanical strength and fatigue resistance of said structural elements 25.

[0086] As is well known to those skilled in the art, the width and height of the print bead depend on the geometric dimensions of the nozzle outlet section 12 and the setting parameters of the additive manufacturing machine 20.

[0087] Advantageously, the nozzle 12 of the additive manufacturing machine 20 can be changed during the manufacturing of a layer of the frame 24 in order to make the width of the deposited bead coincide with the widths RI, R2, R3, R4 and R5 of each of the beads Cl, C2, C3, C4 and C5 of the structural elements 25, allowing a single pass with the nozzle 12 to produce a layer of each of said structural elements 25.

[0088] Preferably, the plurality of connecting portions 26 comprises at least two connecting portions 26 of different patterns, each of the connecting portions 26 of different pattern being distributed circumferentially according to a constant pitch.

[0089] Preferably, the plurality of junction portions 27 comprises at least two junction portions 27 of different patterns, each of the junction portions 27 of different pattern being distributed circumferentially according to a constant pitch.

[0090] According to the process of the invention, the printing material 21 is preferably a polyaryletherketone (PAEK) type thermoplastic, such as for example the AM200® product from Victrex™, a poly-etheretherketone (PEEK) type thermoplastic, an aliphatic polyamide (PA), a polyetherimide (PEI), a polyimide (PI), a glycolized polyester (PETG), or an elastomeric thermoplastic copolyester (TPC-ET) such as, for example, the Hytrel® product from DuPont™.

[0091] Advantageously, the printing material 21 has a melting temperature of at least 180°C and at most 450°C.

[0092] Advantageously, the printing material 21 differs between at least two types of cords among the cords of radially inner membrane C1, radially intermediate membrane C2, radially outer membrane C3, bonding structure C4 and joining structure C5, respectively. Thus, since each of the structural elements 25 has a different functional requirement, for example in rigidity or flexibility, it is possible to choose the material having the most suitable technical characteristics for the realization of each of the structural elements 25.

[0093] The continuity of the C4 bonding structure cord and the C5 junction structure cord minimizes the stop and start phases during the placement of the cords (C4, C5), thus generating time savings and better manufacturing quality of the airless tire carcass.

[0094] The invention can be generalized to the case of a carcass 24 of the airless tire 1 comprising, radially from the inside to the outside: -at least two load-bearing structures 9, the first radially inner membrane 7 of the first load-bearing structure 9 being intended to be fixed to the rim or hub 4, each of the other radially inner membranes 7 serving as an interface between each of the connecting structures 28, -and / or at least two shear bands 3, the last radially outer membrane 5 being intended to receive the tread 2, each of the other radially outer membranes 5 serving as an interface between each of the joining structures 29.

[0095] Table 1 below presents the characteristics of an embodiment of a casing 24 intended for the manufacture of an airless tire 1: [Tables 1] Carcass for the production of a 300 / 90R16 tire. Material: PEEK. Number of layers: 100. Number of bonding sections: 18. Number of joining sections: 18. First arc length L1: 12 mm. Second arc length L2: 30 mm. Third arc length L3: 46 mm. Fourth arc length L4: 52 mm. Maximum thickness of first layer: 11 mm. Maximum thickness of second layer: 22 mm. Maximum thickness of third layer: 3 mm. Maximum thickness of fourth layer: 4 mm. Maximum thickness of fourth layer: 4 mm. Width of first layer: 1.1 mm. Width of second layer: 1.5 mm. Width of third layer: 1.5 mm. Width of fourth layer: 1.36 mm. Width of fifth layer: 1.36 mm. Height H: 300 mm.

[0096] The invention also relates to a carcass 24 made according to the manufacturing process according to the invention, and an airless tire 1 comprising such a carcass 24.

Claims

Demands

1. An additive manufacturing process for a carcass (24) of an airless tire (1) for a vehicle, employing an additive manufacturing machine (20) comprising a build platform (14), perpendicular to the axis of revolution of the carcass (24) having an axial direction Z, and a nozzle (12), capable of moving along the axial direction Z and in any circumferential plane XY perpendicular to the axial direction Z, said additive manufacturing process comprising the following successive steps: (a) manufacturing a first layer of said frame (24), extending along the axial direction Z, by depositing a printing material (21) onto the build platform (14) by said nozzle (12), to form, in any order, beads (Cl, C2, C3, C4, C5) as follows: -a radially inner membrane bead (Cl), intended for the manufacture of a radially inner membrane (7) of the frame (24) and having a first width (RI), -a radially intermediate membrane cord (C2), intended for the manufacture of a radially intermediate membrane (10) of the carcass (24) and having a second width (R2), -a radially external membrane cord (C3), intended for the manufacture of a radially external membrane (5) of the carcass (24) and having a third width (R3), -a bonding structure cord (C4), intended for the fabrication of a bonding structure (28) connecting the radially inner membrane (7) to the radially intermediate membrane (10), via a plurality of bonding portions (26), said bonding structure cord having a fourth width (R4), and said bonding structure cord (C4) having a plurality of first interpenetrating zones (Z1) with said radially inner membrane cord (C1), each of said first interpenetrating zones (Z1) having a first arc length (L1) and, along a radial direction, a first maximum thickness (E1), said bonding structure cord (C4) also having a plurality of second interpenetrating zones (Z2) with said radially intermediate membrane cord (C2), each of said second interpenetrating zones (Z2) having a second arc length (L2) and, along a radial direction, a second maximum thickness (E2), -a junction structure cord (C5), intended for the fabrication of a junction structure (27) connecting the radially intermediate membrane (10) to the radially outer membrane (5) via a plurality of junction portions, said junction structure cord (C5) having a fifth width (R5), and said junction structure cord (C5) having a plurality of third interpenetrating zones (Z3) with said radially intermediate membrane cord (C2), each of said third interpenetrating zones (Z3) having a third arc length (L3) and, along a radial direction, a third maximum thickness (E3), said junction structure cord (C5) also having a plurality of fourth interpenetrating zones (Z4) with said radially outer membrane cord (C3), each of said fourth interpenetrating zones (Z4) having a fourth arc length (L4) and, along a radial direction,a fourth maximum thickness (E4), (b) production of at least one additional layer carried out according to step (a), the (Cl, C2, C3, C4, C5) beads of the at least one additional layer being superimposed in an axial direction Z on the (Cl, C2, C3, C4, C5) beads of the previous axially adjacent layer with remelting of the interface between the previous layer and the at least one additional layer.

2. A method for additively manufacturing a carcass (24) according to claim 1, wherein the first width (RI), the second width (R2), the third width (R3), the fourth width (R4) and the fifth width (R5) are equal to each other.

3. A method for additively manufacturing a carcass (24) according to any one of claims 1 or 2, wherein the first width (RI), the second width (R2), the third width (R3), the fourth width (R4) and the fifth width (R5) are respectively at least equal to 0.15mm and at most equal to 4mm and preferably at least equal to 0.4mm and at most equal to 2mm.

4. A method for additively manufacturing a carcass (24) according to any one of claims 1 to 3, wherein the first maximum thickness (E1), the second maximum thickness (E2), the third maximum thickness (E3) and the fourth maximum thickness (E4) are equal to each other.

5. A method for additively manufacturing a carcass (24) according to any one of claims 1 to 4, wherein the first thickness maximum (El) is at least equal to 2% and at most equal to 20% of the smallest of the first and fourth widths (RI, R4), preferably at least equal to 5% and at most equal to 10% of the smallest of the first and fourth widths (RI, R4).

6. A method for additively manufacturing a carcass (24) according to any one of claims 1 to 5, wherein the second maximum thickness (E2) is at least equal to 2% and at most equal to 20% of the smallest of the second and fourth widths (R2, R4), preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fourth widths (R2, R4).

7. Additive manufacturing method of a carcass (24) according to any one of claims 1 to 6, wherein the maximum third thickness (E3) is at least equal to 2% and at most equal to 20% of the smallest of the second and fifth widths (R2, R5), preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fifth widths (R2, R5).

8. Additive manufacturing method of a carcass (24) according to any one of claims 1 to 7, wherein the maximum fourth thickness (E4) is at least equal to 2% and at most equal to 20% of the smallest of the third and fifth widths (R3, R5), preferably at least equal to 5% and at most equal to 10% of the smallest of the third and fifth widths (R3, R5).

9. A method for additively manufacturing a frame (24) according to any one of claims 1 to 8, wherein the first arc length (L1) is at least equal to 3 times and at most equal to 150 times the smallest of the first and fourth widths (RI, R4), preferably at least equal to 10 times and at most equal to 60 times the smallest of the first and fourth widths (RI, R4).

10. A method for additively manufacturing a frame (24) according to any one of claims 1 to 9, wherein the second arc length (L2) is at least equal to 3 times and at most equal to 150 times the smallest of the second and fourth widths (R2, R4), preferably at least equal to 10 times and at most equal to 60 times the smallest of the second and fourth widths (R2, R4).

11. An additive manufacturing method for a frame (24) according to any one of claims 1 to 10, wherein the third arc length (L3) is at least equal to 3 times and at most equal to 150 times the smaller of the second and fifth widths (R2, R5), preferably to less than or equal to 10 times and at most equal to 60 times the smaller of the second and fifth widths (R2, R5).

12. A method for additively manufacturing a frame (24) according to any one of claims 1 to 11, wherein the fourth arc length (L4) is at least equal to 3 times and at most equal to 150 times the smallest of the third and fifth widths (R3, R5), preferably at least equal to 10 times and at most equal to 60 times the smallest of the third and fifth widths (R3, R5).

13. A method for additively manufacturing a carcass (24) according to any one of claims 1 to 12, wherein the plurality of connecting portions (26) comprises at least two connecting portions (26) of different patterns, each of the connecting portions (26) of different pattern being distributed circumferentially in a constant pitch.

14. A method for additively manufacturing a frame (24) according to any one of claims 1 to 13, wherein the plurality of junction portions (27) comprises at least two junction portions (27) of different patterns, each of the junction portions (27) of different pattern being distributed circumferentially in a constant pitch.

15. A method for additively manufacturing a frame (24) according to any one of claims 1 to 14, wherein the printing material (21) is a polyaryletherketone (PAEK) type thermoplastic, a polyetheretherketone (PEEK) type thermoplastic, an aliphatic polyamide (PA), a polyetherimide (PEI), a polyimide (PI), a glycolized polyester (PETG), or an elastomeric thermoplastic copolyester (TPC-ET).

16. A method for additively manufacturing a frame (24) according to claim 15, wherein the printing material (21) has a melting temperature of at least 180°C and at most 450°C.

17. A method for additively manufacturing a frame (24) according to claim 15, wherein the printing material (21) is different between at least two types of cords among the cords respectively of radially inner membrane (C1), radially intermediate membrane (C2), radially outer membrane (C3), bonding structure (C4) and joining structure (C5).

18. Carcass (24) of an airless tire (1) produced by implementing the manufacturing process according to any one of claims 1 to 17.

19. Airless tire (1) comprising a casing (24) according to claim indication 18.

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