Method for manufacturing an airless tyre by additive manufacturing

Abstract

Method for the additive manufacturing of a carcass (24) intended for the production of an airless tyre (1), said additive manufacturing method implementing an additive manufacturing machine (20) producing, in any XY plane perpendicular to the axis of rotation of said carcass (24), several layers of the structural elements (25) of said carcass (24) by depositing beads of a fusible printing material, the bead of each structural element (25) having a portion, in any XY plane, which is interpenetrated with the bead of each adjacent structural element (25).

Description

Process for producing an airless tire using 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 methods using three-dimensional printing machines for manufacturing airless tires by depositing a malleable printing material in successive layers, using a nozzle.

[0003] A printing machine generally comprises a chamber which forms an enclosure delimited by a wall, and inside which is a plate intended to support a part being printed, as well as a nozzle for supplying the material constituting said part. To be able to generate the shape of the part, drive systems are provided comprising an elevator for moving either the plate or the nozzle vertically, and translation tables crossed relative to each other for horizontally controlling either the plate or the nozzle responsible for delivering the material constituting the part.

[0004] Such printing machines are described in particular by document US 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 performances comparable to those of a conventional tire subjected to the internal pressure of a gas, generally air. An airless tire, mounted on a hub or a rim, is sometimes called a "non-pneumatic elastic wheel".

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

[0007] An airless tire generally comprises, radially from the inside to the outside: - a carcass, made up of structural elements, intended to cooperate with a rim or a 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 the ground.

[0008] The carcass comprises, radially from the inside to the outside: - a supporting structure, intended to structurally carry at least part of the load, - a shear strip, intended to transmit by shear the rolling forces to the supporting structure and to contribute at least in part to carrying the load.

[0009] The supporting structure generally comprises, radially from the inside to the outside: - a radially inner membrane intended to be fixed by connection means to a rim or a hub, -a plurality of radial elements or spokes, intended to be fixed by connection means to the radially inner membrane and to the shear band. However, the supporting structure does not generally delimit 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 with respect to a rim or a hub.

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

[0011] Generally, the tread is fixed to the radially outer membrane of the shear band by fixing means which may be, for example, gluing or hooping means.

[0012] The carcass therefore comprises a plurality of elements called structural elements which may comprise, for example, a radially extending membrane inner, a plurality of spokes, a radially intermediate membrane, a plurality of shear elements and a radially outer membrane.

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

[0014] Such methods of assembling an airless tire have been described, by way of examples, in documents US20220194129A1, W02008 / 136099A1, US9908369B2.

[0015] Although such processes allow the manufacture of airless tire casings, they do have drawbacks, particularly related to the poor adhesion between the different elements that make up this casing.

[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 being added to the variations in positioning of the assembly process, which can consequently harm the overall quality of the airless tire and its performance.

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

[0018] Other methods of manufacturing airless tire carcasses, 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 processes for manufacturing structural elements by molding require the manufacture of expensive tools such as molds and do not allow the production of complex geometries sometimes necessary for the manufacture of structural elements of an airless tire carcass.

[0020] The invention therefore aims to overcome the aforementioned drawbacks and to propose a manufacturing method which allows the simple and low-cost production of a carcass of 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 a method for the additive manufacturing of a carcass of an airless tire for a vehicle, using an additive manufacturing machine comprising a manufacturing plate, perpendicular to the axis of revolution of the carcass having an axial direction Z, and a nozzle, capable of moving in the axial direction Z and in any circumferential plane XY perpendicular to the axial direction Z, said additive manufacturing method comprising the following successive steps: (a) manufacturing a first layer of said carcass, extending in the axial direction Z, by depositing a printing material on the manufacturing plate by said nozzle, to form, in any order, beads as follows: - a radially inner membrane cord, intended for the manufacture of a radially inner membrane of the carcass and having a first width, - a radially intermediate membrane cord, intended for the manufacture of a radially intermediate membrane of the carcass and having a second width, - a radially outer membrane cord, intended for the manufacture of a radially outer membrane of the carcass and having a third width, -a plurality of spoke cords, intended for the manufacture of a plurality of spokes connecting the radially inner membrane to the radially intermediate membrane, and each of said spoke cords having a fourth width, and each of said spoke cords having at least a first interpenetrating zone with said radially inner membrane cords, said first interpenetrating zone having a first arc length and, in a radial direction, a first maximum thickness, each of said spoke cords also having at least a second interpenetrating zone with said radially intermediate membrane cords, said second interpenetrating zone having a second arc length and, in a radial direction, a second maximum thickness, -a plurality of shear element cords, intended for manufacturing a plurality of shear elements connecting the radially intermediate membrane to the radially outer membrane, and each of said shear element cords having a fifth width, and each of said shear element cords having at least a third interpenetrating zone with said radially intermediate membrane cords, said third interpenetrating zone having a third arc length and, in a radial direction, a third maximum thickness, each of said shear element cords also having at least a fourth interpenetrating zone with said radially outer membrane cords, said fourth interpenetrating zone having a fourth arc length and, in a radial direction, a fourth maximum thickness, (b) production of at least one additional layer following step (a), the beads of the at least one additional layer being superimposed in an axial direction Z on the beads of the axially adjacent previous layer with remelting of the interface between the previous layer and the at least one additional layer.

[0022] Essentially, the additive manufacturing method according to the invention makes it possible to obtain a carcass of an airless tire by implementing a unique method of depositing a printing material in the form of cords emerging from 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 constituted by a single cord or "mono-cord", said "mono-cord" making it possible to save time and improve the quality of manufacturing of the carcass of the airless tire, while improving the mechanical resistance of said carcass.

[0023] Consequently, the additive manufacturing method 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 a saving in manufacturing time and an improvement in the quality of 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 for the carcass, as no tools are required to manufacture the various structural elements.

[0025] Thanks to the interpenetration of the beads of material deposited by the nozzle of the additive manufacturing machine in the connection zones of the different structural elements, the adhesion between them of said different structural elements is improved, thus making it possible to obtain better mechanical resistance properties and / or fatigue limit of the carcass.

[0026] Advantageously, the first width, the second width, the third width, the plurality of fourth widths and the plurality of fifth widths are equal to each other, thus making it possible to reduce the preparation time of the carcass model and to save production time.

[0027] Advantageously, the first width, the second width, the third width, the plurality of fourth widths and the plurality of fifth widths are respectively at least equal to 0.15 mm and at most equal to 4 mm and preferably at least equal to 0.4 mm and at most equal to 2 mm, such dimensional ranges making it possible to manufacture the object with standard nozzle diameters and existing settings of the additive manufacturing machine parameters.

[0028] 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 preparation time of the carcass model 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] Still 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 smallest of the second and fifth widths, preferably at least equal to 5% and at most equal to 10% of the smallest of the second and fifth widths.

[0032] Advantageously, the fourth maximum 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 make it possible to maximize the interpenetration of the successive layers without causing excess material which would accumulate and lead to manufacturing defects, or even the shutdown and degradation of the machine.

[0034] Advantageously, the first arc length, the second arc length, the third arc length and the fourth arc length are equal to each other, thus reducing the preparation time of the carcass model and saving production time.

[0035] Advantageously, the first arc length is at least equal to 3 times and at most equal to 100 times the smallest of the first and fourth widths, preferably at least equal to 10 times and at most equal to 50 times the smallest of the first and fourth widths.

[0036] Still advantageously, the second arc length is at least equal to 3 times and at most equal to 100 times the smallest of the second and fourth widths, preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fourth widths.

[0037] Further advantageously, the third arc length is at least equal to 3 times and at most equal to 100 times the smallest of the second and fifth widths, preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fifth widths.

[0038] Further advantageously, the fourth arc length is at least equal to 3 times and at most equal to 100 times the smallest of the third and fifth widths, preferably at least equal to 10 times and at most equal to 50 times the smallest of the third and fifth widths.

[0039] The previously defined intervals for the first, second, third and fourth arc lengths allow sufficient adhesion to be obtained between the structural elements without increasing the rigidity and mass of the wheel.

[0040] Preferably, the spokes are distributed circumferentially according to a constant pitch.

[0041] Always preferably, the shear elements are distributed circumferentially according to a constant pitch.

[0042] The distribution of the spokes and shear elements at a constant pitch 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.

[0043] Preferably, the printing material is a thermoplastic of the polyaryletherketone type (PAEK), a thermoplastic of the polyetheretherketone type (PEEK), an aliphatic polyamide (PA), a polyetherimide (PEI), a polyimide (PI), a polyester glycol (PETG), or a thermoplastic elastomeric copolyester (TPC-ET). An example of a polyaryletherketone (PAEK) is the AM 200® product from Victrex™. An ​​example of a thermoplastic elastomeric copolyester (TPC-ET) is the Hytrel® product from DuPont™.

[0044] Advantageously, the printing material has a melting temperature at least equal to 180°C and at most equal to 450°C, allowing on the one hand to have sufficient thermal resistance in operation for low-demand uses, and on the other hand good malleability during the manufacture of the carcass of the invention.

[0045] 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, spokes and shear elements, thus making it possible to specify the stiffness or flexibility for each of the structural elements.

[0046] The invention also relates to a carcass produced according to the manufacturing method according to the invention, and an airless tire comprising such a carcass.

[0047] Other objects, characteristics and advantages of the invention will appear in more detail on reading the description which follows, as well as with the aid of the appended drawings, provided for purely illustrative and non-limiting purposes: - Figure 1: Overall and perspective view of an airless tire comprising a carcass produced by the additive manufacturing process according to the invention. - Figure 2: Overview of an additive manufacturing machine used to implement the method of the invention. - Figure 3: Overall and top view of the first layer deposited on the airless tire carcass manufacturing plate. - Figure 4: Axial and partial sectional view of an airless tire produced according to the method of the invention. - Figure 5: Circumferential and partial sectional view of an airless tire carcass produced according to the method of the invention. - Figure 6: Circumferential sectional view of the first interpenetration zone. - Figure 7: Circumferential sectional view of the second interpenetration zone. - Figure 8: Circumferential sectional view of the third and fourth interpenetration zones.

[0048] In the following, for the sake of clarity, the horizontal direction and the vertical direction correspond to the natural orientation of Figures 1 to 7. Similarly, the terms "top", "bottom", "lower", "upper" and their variants should be understood with reference to the vertical direction of the figures.

[0049] As seen in Figure 1, an airless tire 1 comprises, radially from the inside to the outside: - a carcass 24 intended to cooperate with a rim or a hub 4, - a tread 2, intended to cooperate with the carcass 24.

[0050] The carcass 24 comprises, radially from the inside to the outside: - a supporting structure 9, intended to cooperate with the rim or the hub 4, - a shear band 3, intended to cooperate with the tread 2.

[0051] The supporting structure 9 comprises radially from the inside to the outside: - a radially inner membrane 7 intended to be fixed by connection means to the rim or hub 4, - a plurality of radial elements or spokes 8 intended to connect the radially inner membrane 7 and the shear band 3.

[0052] The means for connecting the radially inner membrane 7 to the rim or hub 4 may be, for example, means of gluing, riveting, bolting or hooping.

[0053] The shear band 3 comprises, in a known embodiment, radially from the inside to the outside: - a radially intermediate membrane 10, interfacing with the supporting structure 9, - a plurality of shear elements 11, - a radially outer membrane 5, intended to receive the tread 2 and connected to the radially intermediate membrane 10 by the plurality of shear elements 11.

[0054] The tread 2 may be fixed to the radially outer membrane 5 of the shear band 3 by fixing means which may be, for example, gluing or hooping means.

[0055] The carcass 24 is thus made up of structural elements 25 comprising the radially inner membrane 7, the spokes 8, the radially intermediate membrane 10, the shear elements 11 and the radially outer membrane 5.

[0056] The present invention relates to a method for producing the carcass 24 of an airless tire 1 using an additive manufacturing machine 20.

[0057] Figure 2 is an overview of an example of an additive manufacturing machine 20 implemented to carry out the method according to the invention. The additive manufacturing machine 20 comprises a nozzle 12, a manufacturing plate 14, a horizontal movement system 22 in any circumferential plane XY, and a vertical movement system 23 in an axial direction Z, perpendicular to any circumferential plane XY.

[0058] The horizontal movement system 22 and the vertical movement system 23 make it possible to control a relative movement of the nozzle 12 with respect to the manufacturing plate 14 so that said nozzle 12 can deposit a molten printing material 21 in the form of preferably continuous beads 13.

[0059] Any other type of additive manufacturing machine by depositing 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 manufacturing plate 14 is achieved by the movement of said manufacturing plate 14.

[0060] According to a first step of the method of the invention, a first layer of the carcass 24, extending in the axial direction Z, will be produced by the deposition of a printing material 21 on the manufacturing plate 14 by the nozzle 12, to form, in any order, beads (C1, C2, C3, C4, C5).

[0061] As can be seen in Figures 3 and 5, the nozzle 12 will deposit: -a radially inner membrane cord C1, intended for the manufacture of the radially inner membrane 7 of the carcass 24 and having a first width R1, -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 outer membrane cord C3, intended for the manufacture of the radially outer membrane 5 of the carcass 24 and having a third width R3, -a plurality of spoke cords C4, intended for the manufacture of the plurality of spokes 8 connecting the radially inner membrane 7 to the radially intermediate membrane 10, and each of said spoke cords C4 having a fourth width R4, -a plurality of shear element cords C5, intended for the manufacture of the plurality of shear elements 11 connecting the radially intermediate membrane 10 to the radially outer membrane 5, and each of said shear element cords having a fifth width R5.

[0062] As illustrated in Figure 6, each of the radius cords C4 has at least a first interpenetrating zone Z 1 with the radially adjacent membrane cords interior Cl, said first interpenetrated zone ZI having a first arc length L1 and, in a radial direction, a first maximum thickness El.

[0063] As shown in Figure 7, each of the radius cords C4 also has at least one second interpenetrating zone Z2 with the radially intermediate membrane cords C2, said second interpenetrating zone Z2 having a second arc length L2 and, in a radial direction, a second maximum thickness E2.

[0064] As seen in Figure 8, each of the shear element cords C5 has at least a third interpenetrating zone Z3 with the radially intermediate membrane cords C2, said third interpenetrating zone Z3 having a third arc length L3 and, in a radial direction, a third maximum thickness E3.

[0065] As can be seen in Figure 8, each of the shear element cords C5 also has at least a fourth interpenetrating zone Z4 with the radially outer membrane cords C3, said fourth interpenetrating zone Z4 having a fourth arc length L4 and, in a radial direction, a fourth maximum thickness E4.

[0066] According to the method of the invention, the nozzle 12 will then produce at least one additional layer following step a, the beads (C1, C2, C3, C4, C5) of the at least one additional layer being superimposed in an axial direction Z on the beads (C1, C2, C3, C4, C5) of the axially adjacent previous layer with reflow of the interface between the previous layer and the at least one additional layer.

[0067] As can be seen in Figure 4, the repetition of step (a) will make it possible to produce a single-piece carcass 24, of height H in 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.

[0068] Remelting the interface between two adjacent layers allows for a very strong bond between each layer, thus making it possible to manufacture 24-piece monobloc carcasses with high mechanical strength.

[0069] The creation of interpenetration zones Z 1, Z2, Z3 and Z4 during the deposition of the printing material 21 allows, on the one hand, the spokes 8 to adhere perfectly to the radially inner membrane 7 and to the radially intermediate membrane 10, and on the other hand, the shear elements 11 to also adhere perfectly to the radially intermediate membrane 10 and to the radially outer membrane 5.

[0070] This perfect adhesion between the structural elements 25 of the carcass 24 makes it possible to obtain very high mechanical resistance and very good fatigue resistance of said carcass 24 during operating stresses.

[0071] Preferably, when manufacturing a layer of the carcass 24, the nozzle 12 begins the deposition of a layer of the radially inner membrane bead C1, which is a bead delimiting a closed zone, at a starting point which is different from the starting point of the previous layer, in order to obtain junction zones located at different horizontal azimuths between two adjacent layers.

[0072] In the same way, the deposition of a layer of the other beads C2, C3, each also delimiting a closed zone, is also preferably done with starting and finishing points of the nozzle 12 different from the previous layer, also making it possible to obtain junction zones, between the beginnings and the ends of beads, located according to different horizontal azimuths.

[0073] Obtaining, for each of the layers of the carcass 24, junction zones located according to different horizontal azimuths for the cords delimiting closed zones makes it possible to reinforce the mechanical resistance of the carcass 24 by avoiding the propagation of possible cracks in said junction zones.

[0074] In a particular embodiment, and as illustrated in Figure 5, the first width R1, the second width R2, the third width R3, the plurality of fourth widths R4 and the plurality of fifth widths 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.

[0075] In another embodiment, it is possible to optimize the strength 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 carcass 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.

[0076] These differences in thickness also make it possible to reduce the weight of the carcass 24, and to save on the quantity of material deposited and on manufacturing time.

[0077] Preferably, and as can be seen in Figure 5, 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.

[0078] Still preferably, the first arc length L1, the second arc length L2, the third arc length L3 and the fourth arc length L4 are equal to each other.

[0079] Advantageously, the first maximum thickness E1 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.

[0080] Still 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.

[0081] Still 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.

[0082] Still 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.

[0083] Advantageously, the first arc length Ll is at least equal to 3 times and at most equal to 100 times the smallest of the first and fourth widths RI, R4, of preferably at least equal to 10 times and at most equal to 50 times the smallest of the first and fourth widths RI, R4.

[0084] Still advantageously, the second arc length L2 is at least equal to 3 times and at most equal to 100 times the smallest of the second and fourth widths R2, R4, preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fourth widths R2, R4.

[0085] Still advantageously, the third arc length L3 is at least equal to 3 times and at most equal to 100 times the smallest of the second and fifth widths R2, R5, preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fifth widths R2, R5.

[0086] Still advantageously, the fourth arc length L4 is at least equal to 3 times and at most equal to 100 times the smallest of the third and fifth widths R3, R5, preferably at least equal to 10 times and at most equal to 50 times the smallest of the third and fifth widths R3, R5.

[0087] As can be seen in Figure 5, in the interpenetrated zones Z1, Z2, Z3, Z4, the cord of a structural element 25 of the carcass 24 is tangent to the cord of the adjacent structural element 25. This tangency makes it possible to give the structural elements 25 geometries adapted to the types of stresses undergone by the carcass 24, thus improving the mechanical strength and fatigue resistance of said structural elements 25.

[0088] 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 outlet section of the nozzle 12 and the adjustment parameters of the additive manufacturing machine 20.

[0089] Advantageously, the nozzle 12 of the additive manufacturing machine 20 may be changed during the manufacturing of a layer of the carcass 24 in order to make the width of the deposited bead coincide with the widths R1, R2, R3, R4 and R5 of each of the beads C1, C2, C3, C4 and C5 of the structural elements 25, making it possible to make a single pass with the nozzle 12 to produce a layer of each of said structural elements 25.

[0090] Preferably, the spokes 8 and the shear elements 11 are distributed circumferentially at a constant pitch.

[0091] Still according to the method of the invention, the printing material 21 is, preferably, a thermoplastic of the polyaryletherketone (PAEK) type, such as for example the AM200® product from the company Victrex™, a thermoplastic of the polyetheretherketone (PEEK) type, an aliphatic polyamide (PA), a polyetherimide (PEI), a polyimide (PI), a glycolized polyester (PETG), or a thermoplastic elastomeric copolyester (TPC-ET) such as, for example, the Hytrel® product from the company DuPont™.

[0092] Advantageously, the printing material 21 has a melting temperature at least equal to 180°C and at most equal to 450°C.

[0093] Advantageously, 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, spokes C4 and shear elements C5. Thus, each of the structural elements 25 having a different functional need, for example in rigidity or flexibility, it is possible to choose the material having the most suitable technical characteristics for the production of each of the structural elements 25.

[0094] It is possible to generalize the invention to the case of a carcass 24 of the airless tire 1 comprising, radially from the inside to the outside: -at least two supporting structures 9, the first radially inner membrane 7 of the first supporting structure 9 being intended to be fixed to the rim or to the hub 4, each of the other radially inner membranes 7 serving as an interface between each of the pluralities of radial elements or spokes 8, -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 pluralities of shear elements 11.

[0095] Table 1 below presents the characteristics of an embodiment of a carcass 24 intended for the manufacture of an airless tire 1: [Table 1]

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

Claims

Claims Method for additive manufacturing of a carcass (24) of an airless tire (1) for a vehicle, using an additive manufacturing machine (20) comprising a manufacturing plate (14), perpendicular to the axis of revolution of the carcass (24) having an axial direction Z, and a nozzle (12), capable of moving in the axial direction Z and in any circumferential plane XY perpendicular to the axial direction Z, said additive manufacturing method comprising the following successive steps: (a) manufacturing a first layer of said carcass (24), extending in the axial direction Z, by depositing a printing material (21) on the manufacturing plate (14) by said nozzle (12), to form, in any order, beads (C1, C2, C3, C4, C5) as follows: - a radially inner membrane cord (Cl), intended for the manufacture of a radially inner membrane (7) of the carcass (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 outer membrane cord (C3), intended for the manufacture of a radially outer membrane (5) of the carcass (24) and having a third width (R3), -a plurality of spoke cords (C4), intended for the manufacture of a plurality of spokes (8) connecting the radially inner membrane (7) to the radially intermediate membrane (10), and each of said spoke cords having a fourth width (R4), and each of said spoke cords (C4) having at least a first interpenetrating zone (Zl) with said radially inner membrane cords (Cl), said first interpenetrating zone (Zl) having a first arc length (Ll) and, in a radial direction, a first maximum thickness (El), each of said spoke cords (C4) also having at least one second interpenetrating zone (Z2) with said radially intermediate membrane cords (C2), said second interpenetrating zone (Z2) having a second arc length (L2) and, in a radial direction, a second maximum thickness (E2), -a plurality of shear element cords (C5), intended for manufacturing a plurality of shear elements (11) connecting the radially intermediate membrane (10) to the radially outer membrane (5), and each of said shear element cords (C5) having a fifth width (R5), and each of said shear element cords (C5) having at least a third interpenetrating zone (Z3) with said radially intermediate membrane cords (C2), said third interpenetrating zone (Z3) having a third arc length (L3) and, in a radial direction, a third maximum thickness (E3), each of said shear element cords (C5) also having at least a fourth interpenetrating zone (Z4) with said radially outer membrane cords (C3), said fourth interpenetrating zone (Z4) having a fourth arc length (L4) and, in a radial direction radial, a fourth maximum thickness (E4), (b) producing at least one additional layer following step (a), the beads (Cl, C2, C3, C4, C5) of the at least one additional layer being superimposed in an axial direction Z on the beads (Cl, C2, C3, C4, C5) of the axially adjacent preceding layer with reflow of the interface between the preceding layer and the at least one additional layer. A method of additive manufacturing a carcass (24) according to claim 1, wherein the first width (RI), the second width (R2), the third width (R3), the plurality of fourth widths (R4) and the plurality of fifth widths (R5) are equal to each other. Method for additively manufacturing a carcass (24) according to one of claims 1 or 2, in which the first width (RI), the second width (R2), the third width (R3), the plurality of fourth widths (R4) and the plurality of fifth widths (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. Method for additive manufacturing of a carcass (24) according to any one of claims 1 to 3, in which 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. Method for additive manufacturing of a carcass (24) according to any one of claims 1 to 4, in which 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).

6. Method for additive manufacturing of a carcass (24) according to any one of claims 1 to 5, in which 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. Method for additive manufacturing of a carcass (24) according to any one of claims 1 to 6, in which 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).

8. Method for additive manufacturing of a carcass (24) according to any one of claims 1 to 7, in which 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).

9. A method of additively manufacturing a carcass (24) according to any one of claims 1 to 8, wherein the first arc length (L1), the second arc length (L2), the third arc length (L3) and the fourth arc length (L4) are equal to each other.

10. A method of additive manufacturing a carcass (24) according to any one of claims 1 to 9, wherein the first arc length (L1) is at least equal at least 3 times and at most equal to 100 times the smallest of the first and fourth widths (RI, R4), preferably at least equal to 10 times and at most equal to 50 times the smallest of the first and fourth widths (RI, R4). A method of additive manufacturing a carcass (24) according to any one of claims 1 to 10, wherein the second arc length (L2) is at least equal to 3 times and at most equal to 100 times the smallest of the second and fourth widths (R2, R4), preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fourth widths (R2, R4). A method of additively manufacturing a carcass (24) according to any one of claims 1 to 11, wherein the third arc length (L3) is at least equal to 3 times and at most equal to 100 times the smallest of the second and fifth widths (R2, R5), preferably at least equal to 10 times and at most equal to 50 times the smallest of the second and fifth widths (R2, R5).A method of additively manufacturing a carcass (24) according to any one of claims 1 to 12, wherein the fourth arc length (L4) is at least equal to 3 times and at most equal to 100 times the smallest of the third and fifth widths (R3, R5), preferably at least equal to 10 times and at most equal to 50 times the smallest of the third and fifth widths (R3, R5). A method of additively manufacturing a carcass (24) according to any one of claims 1 to 13, wherein the radii (8) are distributed circumferentially at a constant pitch. A method of additively manufacturing a carcass (24) according to any one of claims 1 to 14, wherein the shear elements (11) are distributed circumferentially at a constant pitch.A method of additively manufacturing a carcass (24) according to any one of claims 1 to 15, 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 a thermoplastic elastomeric copolyester (TPC-ET). Method for additively manufacturing a carcass (24) according to claim 16, wherein the printing material (21) has a melting temperature at least equal to 180°C and at most equal to 450°C. Method for additively manufacturing a carcass (24) according to claim 16, 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), spokes (C4) and shear elements (C5). Carcass (24) of an airless tire (1) produced by implementing the manufacturing method according to one of claims 1 to 18. Airless tire (1) comprising a carcass (24) according to claim 19.

Images