Method for manufacturing support structure having cord-reinforced polymer composition spoke for non-pneumatic tire
The method of encapsulating cord reinforcement within polymer layers in non-pneumatic tire spokes addresses durability issues by hiding the reinforcement and enabling efficient manufacturing, enhancing tire performance and production efficiency.
Patent Information
- Application Number
- JP2024217655
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-12
- Filing Date
- 2024-12-12
- Publication Date
- 2025-07-15
AI Technical Summary
Existing non-pneumatic tires face challenges in improving the durability of polymer spokes, as current reinforcement methods do not effectively prevent cord exposure on the surface and lack efficient manufacturing processes.
A method involving a first mold member covered by a polymer composition layer, with cord reinforcement disposed on it, followed by overmolding a second polymer layer to encapsulate the cord, ensuring the reinforcement is hidden within the spoke structure.
This method enhances spoke durability by preventing cord exposure and allows for precise positioning, facilitating cost-effective mass production of cord-reinforced polymer composition spokes for non-pneumatic tires.
Smart Images
Figure 2025106206000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a support structure for a non-pneumatic tire having a cord-reinforced polymer composition spoke. Further, the present invention relates to a method for manufacturing a non-pneumatic tire having such a support structure and / or a spoke.
Background Art
[0002] Some non-pneumatic tires have a support structure disposed between a tread band and a hub portion and including a plurality of spokes. In some cases, such spokes include a polymer material. To improve the durability of the spokes, the spokes may be reinforced with cords or fiber materials. Although progress has been made over the past several years in the development of polymer spokes for non-pneumatic tires, there is still much room for improvement.
Summary of the Invention
Means for Solving the Problems
[0003] In a first aspect, the present invention relates to a method for manufacturing a support structure for a non-pneumatic tire having at least one cord-reinforced polymer composition spoke. The method includes providing a first mold member at least partially covered by a first polymer composition layer, disposing at least one cord reinforcement on the first polymer composition layer, and overmolding a second polymer composition layer on the first polymer composition layer to encapsulate the cord reinforcement between the first polymer composition layer and the second polymer composition layer to obtain at least a part of a cord-reinforced polymer composition spoke.
[0004] In a second aspect, the present invention relates to a method of manufacturing a support structure for a non-pneumatic tire having at least one X-shaped cord-reinforced polymer composition spoke, the X-shaped spoke having a pair of upper legs and a pair of lower legs connected by an intersection. The method includes providing a mold having mold members, the mold members including: i) a prismatic first mold insert for defining an inner surface between the upper legs of the X-shaped spoke; ii) a prismatic second mold insert for defining an inner surface between the lower legs of the X-shaped spoke; and iii) at least one further separate mold member for defining an outer surface essentially opposite to the inner surface defined by the first and second mold inserts of the X-shaped spoke, at least one of the mold members being at least partially covered by at least one polymer composition layer. Further steps of the method include placing a cord reinforcement on the polymer composition layer and injection molding a further polymer composition over the cord reinforcement and the polymer composition layer to encapsulate the cord reinforcement with the further polymer composition and the polymer composition layer.
[0005] In a third aspect of the present invention, the present invention has a circumferential tread band on the outer radial side, a hub portion on the inner radial side, and a circumferential support structure that supports the circumferential tread band on the outer radial side on the hub portion on the inner radial side. The support structure has a circumferential outer radial ring portion, a circumferential inner radial ring portion, and a plurality of cord-reinforced polymer composition spokes provided along the circumferential direction and arranged between the outer radial ring portion and the inner radial ring portion, and relates to a method for manufacturing a non-pneumatic tire. The method includes a step of preparing a mold for molding at least a circumferential sector of the circumferential support structure, the mold having an outer radial mold ring member for molding the outer radial side of at least the circumferential sector of the outer radial ring portion, an inner radial mold ring member for molding the inner radial side of at least the circumferential sector of the inner radial ring portion, and a mold insert for molding the spokes of the plurality of spokes between the mold ring members, and most of the mold members being covered by a polymer composition layer. The method further includes a step of arranging a cord reinforcement for reinforcing and connecting a plurality of spokes provided along the circumferential direction to be molded on at least a part of the polymer composition layer, and a step of injection molding another polymer composition on the cord reinforcement and the polymer composition layer and confining the cord reinforcement with the other polymer composition and the polymer composition layer.
Brief Description of the Drawings
[0006]
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DETAILED DESCRIPTION OF THE INVENTION
[0007] In a first aspect, the present invention relates to a method for manufacturing a support structure for a non-pneumatic tire having at least one cord-reinforced polymer composition spoke. The method includes providing a first mold member at least partially covered by an optionally preformed first polymer composition layer, disposing at least one cord reinforcement on the first polymer composition layer, and overmolding a second polymer composition layer over the first polymer composition layer (and the cord reinforcement) to encapsulate, i.e., confine, the cord reinforcement between the first polymer composition layer and the second polymer composition layer and / or obtain at least a portion of the cord-reinforced polymer composition spoke.
[0008] Providing the polymer composition layer helps prevent the cord reinforcement from being exposed on the surface of the spoke or a part thereof. In particular, due to the material thickness of the first polymer composition layer (which is preferably solid when arranging the cord reinforcement), when the cord reinforcement is arranged on the first polymer composition layer covering the first mold member, it is prevented from contacting the adjacent part of the first mold member. Thus, when removing the first mold member (and optionally further mold members), the cord reinforcement is still covered and / or hidden by the first (and second) polymer composition layers. Also, this method enables arranging one or more cord reinforcements in the spoke, such as at the central part of the spoke thickness, as per the specification.
[0009] In one embodiment, the first polymer composition layer has at least one groove, and a cord reinforcement such as a cord or a cord reinforcement tape is arranged on the first polymer composition layer within the groove. Preferably, the depth of the groove is smaller than the maximum thickness of the first polymer composition layer such that the cord reinforcement is arranged on the material of the polymer composition layer within the groove. Such grooves help further define the position of the cord reinforcement in the manufactured spoke and / or help prevent the movement of the cord reinforcement during the overmolding. Optionally, a plurality of preferably parallel grooves and / or segments thereof are provided on the first polymer composition layer, thereby enabling arranging a plurality of parallel cord reinforcements or cord reinforcement segments on the first polymer composition layer and thus within the spoke. In particular, the grooves can limit the lateral movement of the cord reinforcement with respect to the extension of the groove.
[0010] In another embodiment, the first mold member is a mold insert and / or the method further includes the step of providing at least one second mold member that forms a gap between the first polymer composition layer on the first mold insert / member and the second mold member. Optionally, the step of overmolding the second polymer composition layer includes injecting the second polymer composition into the gap to form the second polymer composition layer.
[0011] In another embodiment, the first mold member is at least partially encapsulated by the first polymer composition layer. Optionally, the first polymer composition layer forms a sleeve that covers the surface of the first mold member.
[0012] In yet another embodiment, the first mold member essentially has a prismatic shape with three circumferentially adjacent sides encapsulated by the first polymer composition layer.
[0013] In yet another embodiment, the first polymer composition and / or the second polymer composition includes one or more of an elastomer composition (such as a rubber composition) and a thermoplastic polymer (such as a thermoplastic elastomer like a thermoplastic polyester elastomer).
[0014] In one embodiment, the first polymer composition and the second polymer composition are the same. For example, this can contribute to providing the same material properties throughout the spoke. By using the same material, the bond between the two layers can be improved.
[0015] In another embodiment, the first polymer composition and the second polymer composition are different. In some cases, it may be desirable to provide different material properties to a part or side of the spoke. The method provides an easy and efficient way to provide such different properties by providing at least two different polymer compositions. Optionally, when different polymer compositions are used, they are one or more of i) capable of bonding to each other and / or being compatible, ii) both being an elastomer composition such as a rubber composition, and iii) being co-curable with each other.
[0016] In yet another embodiment, the polymer may be one or more of i) one or more polyamide polymers (such as PA-12, PA-11, PA-6, etc.), and ii) one or more thermoplastic polymers, for example, one or more of thermoplastic polyester elastomers, thermoplastic polyurethane elastomers, polyamide thermoplastic elastomers, elastomer alloy thermoplastic vulcanizates, thermoplastic polyolefin elastomers, styrenic thermoplastic elastomers, thermoplastic resins (such as polyester resins, polyamide resins, polyurethane resins, etc.). In particular, the thermoplastic polymer shall also include thermoplastic resins herein.
[0017] In yet another embodiment, the thermoplastic polymer is a thermoplastic elastomer such as a thermoplastic polyester elastomer.
[0018] In another preferred embodiment, the polymer composition is an elastomer composition such as a rubber composition. Optionally, the elastomer composition (such as a rubber composition) includes one or more of rubber (such as those containing one or more of natural rubber, synthetic polyisoprene, butadiene rubber, styrene-butadiene rubber, and butyl rubber), filler (such as those containing one or more of carbon black and silica), resin (such as hydrocarbon resins selected from one or more of coumarone-indene resins, petroleum hydrocarbon resins, terpene resins, styrene / alpha-methylstyrene resins, terpene phenol resins, rosin-derived resins, and their copolymers and / or mixtures), accelerator, antioxidant, oil, liquid diene polymer, coupling agent (such as carbon black coupling agent or silane), sulfur donor, and sulfur. Here, the term "liquid" means that the material is in a liquid state at 23°C. The composition may be a sulfur-curable or sulfur-cured rubber composition. Optionally, the elastomer composition such as a rubber composition may be fiber-reinforced.
[0019] In yet another embodiment, the elastomer composition or rubber composition comprises 100 phr of rubber, including one or more of natural rubber, synthetic polyisoprene, polybutadiene rubber, and styrene-butadiene rubber. Preferably, the composition comprises at least 50 phr of natural rubber (such as 50 - 100 phr of natural rubber), and optionally, 0 - 50 phr, or 5 - 50 phr of polybutadiene rubber. Further, the elastomer or rubber composition preferably comprises a filler including carbon black and / or silica. For example, such a filler may be in the range of 20 - 150 phr, preferably 30 - 90 phr. Preferably, such a filler mainly comprises carbon black. The elastomer or rubber composition may further comprise 1 - 40 phr of resin, preferably including a phenolic resin. Further, the elastomer or rubber composition may comprise 1 - 30 phr, preferably 1 - 20 phr of oil. Finally, the elastomer or rubber composition may typically comprise 1 - 15 phr of an anti-degradant, 0.5 - 10 phr of an accelerator, 0.1 - 10 phr of zinc oxide, and 0.5 - 10 phr of sulfur. Other components may also be included.
[0020] In yet another embodiment, the cord reinforcement is selected from one or more of i) at least one cord, ii) at least one cord reinforcement tape, and iii) at least one fabric comprising cords. In one option, the cord reinforcement has or consists of at least one cord. Preferably, the cord is either a multifilament cord or a monofilament cord. In another option, the cord reinforcement tape is a plurality of essentially parallel cords optionally embedded in a polymer composition such as a resin composition and / or connected by the polymer composition to form a tape, and the polymer composition may include one or more of polyester, vinyl ester, polyurethane, and epoxy. In another option, the fabric may preferably include a plurality of essentially parallel cords that are interconnected. Optionally, these cords may form the warp cords and / or weft cords of the fabric.
[0021] In yet another embodiment, the cord reinforcement, particularly one or more cords of the cord reinforcement, includes or consists of one or more of a fiber material, a glass fiber material, a carbon fiber material, a boron fiber material, a basalt fiber material, a plant-derived material, and combinations of these materials. Optionally, the plurality of cords include different materials and / or are hybrid cords of such different materials. Optionally, the plant-derived material includes one or more of cotton, hemp, flax, sisal, and bast.
[0022] In yet another embodiment, the cord reinforcement, particularly one or more cords of the cord reinforcement, includes or consists of a fiber material selected from one or more of polyester (preferably PET), polyamide (preferably PA-6, PA-6,6, such as nylon®, and aromatic polyamide / aramid), and rayon. Optionally, one or more of these materials may be recycled materials. Optionally, the plurality of cords include different materials and / or are hybrid cords of such different materials.
[0023] In yet another embodiment, the cord reinforcement, in particular one or more cords of the cord reinforcement, comprises or consists of a metal such as steel or brass-coated steel.
[0024] In another embodiment, the cord reinforcement provided herein is either a single filament cord or a multifilament cord. For example, the cord may have a (maximum) diameter in the range of 0.01 - 2 mm, preferably 0.01 - 1 mm, measured perpendicular to the extension of the cord in the spoke.
[0025] In yet another embodiment, the first polymer composition layer is solid when the cord reinforcement is placed on the first polymer composition layer.
[0026] In yet another embodiment, the first mold member essentially has a prismatic shape with three circumferentially adjacent sides wrapped by the first polymer composition layer, and the method comprises providing a further separate mold member essentially having a prismatic shape with three circumferentially adjacent sides wrapped by a further separate polymer composition layer (the same as or different from the first polymer composition and / or the second polymer composition), wherein the first mold member and the further separate mold member are arranged such that their edges face each other and / or are parallel to each other, and providing a further separate mold member; arranging a cord reinforcement on at least one side of the first mold member wrapped by the first polymer composition layer and / or on at least one side of the further separate mold member wrapped by the further separate polymer composition layer, and including at least one of these steps. Preferably, the prismatic shape is a triangular prism shape, i.e., a prismatic shape having a triangular base. The shape or corners of the triangle can be optionally curved.
[0027] In another embodiment, the step of providing the first mold member covered by the first polymer composition layer includes a sub-step of pre-molding and / or over-molding the first polymer composition layer on the first mold member. Optionally, the corresponding steps can be applied to the other / further different layers mentioned herein and the respective mold members.
[0028] In another embodiment, the first polymer composition layer includes a pre-step of forming the first polymer composition layer in another mold system and then subsequently placing the first polymer composition layer on the first mold member.
[0029] In yet another embodiment, a plurality of spaced-apart portions of the cord reinforcement (i.e., the same cord reinforcement) are disposed on the first polymer composition layer. Preferably, the cord reinforcement is herein either a cord reinforcement tape or a cord.
[0030] In yet another embodiment, the portions of the cord reinforcement disposed on the first polymer composition layer are disposed side by side on the first polymer composition layer, such as in the grooves of the first polymer composition layer arranged side by side.
[0031] In yet another embodiment, the (adjacent) portions of the cord reinforcement arranged side by side are spaced apart from each other, i.e., spaced apart from each other.
[0032] In yet another embodiment, the spoke essentially includes or has an X-shaped cross-section. Preferably, the cross-section extends in a plane parallel to the equatorial plane of the tire or in a plane parallel to the circumferential centerline of the tire, which are known to those skilled in the art.
[0033] In yet another embodiment, the spoke has an essentially X-shaped cross-section having a pair of upper legs, a pair of lower legs, and an intersection connecting the pair of upper legs and the pair of lower legs. Optionally, a first mold member is disposed between the upper legs to at least partially define the boundary of the pair of upper legs on the inside, and yet another mold member is disposed between the lower legs to at least partially define the boundary of the pair of lower legs on the inside. As another option, the method further includes providing one or more additional mold members opposite the first mold member and yet another mold member to define the boundaries of the upper and lower legs on the outside (of the spoke and / or its legs).
[0034] In yet another embodiment, the method further includes removing, after overmolding, the first mold member and optionally a second mold member and / or yet another mold member. That is, the first polymer composition layer and preferably yet another polymer composition layer become part or an integral part of the spoke. Additionally or alternatively, the first mold member and optionally the second mold member and / or yet another mold member are removed or separated from the spoke having the polymer composition layer by removing those layers therefrom.
[0035] In yet another embodiment, the support structure has from 4 to 100 spokes, preferably from 20 to 70 spokes, more preferably from 30 to 70 spokes.
[0036] In a second aspect, the present invention relates to a method of manufacturing a support structure for a non-pneumatic tire having at least one X-shaped cord-reinforced polymer composition spoke, the X-shaped spoke having a pair of upper legs and a pair of lower legs connected by an intersection. The method includes providing a mold having mold members, the mold members including: i) a prismatic first mold insert (or member) for defining an inner surface between the upper legs of the X-shaped spoke; ii) a prismatic second mold insert (or member) for defining an inner surface between the lower legs of the X-shaped spoke; and iii) at least one further separate mold member for defining an outer surface essentially opposite to the inner surfaces defined by the first and second mold inserts of the X-shaped spoke, at least one (or a plurality or majority) of the mold members being at least partially covered by at least one polymer composition layer. Further method steps include placing a cord reinforcement on the polymer composition layer and injection molding a further polymer composition onto the cord reinforcement and the polymer composition layer to enclose (or encapsulate) the cord reinforcement with the further polymer composition and the polymer composition layer.
[0037] Similar to the first aspect, the method according to the second aspect provides an improved method of providing cord-reinforced spokes of a support structure of a non-pneumatic tire. In particular, if desired, for example, in one or more legs of the spoke, a cord reinforcement can be provided in a central portion with respect to the thickness of the spoke. That is, according to the present invention, it is possible to highly and / or easily position one or more cord reinforcements within the manufactured spoke.
[0038] In one embodiment, at least a portion of the polymer composition layer has at least one groove extending essentially parallel to and / or along the leg of the spoke, and the cord reinforcement is optionally disposed on the polymer composition layer within the groove so as to restrict movement of the cord reinforcement perpendicular to the groove. In one option, the cord reinforcement is a cord or a cord reinforcement tape.
[0039] In another embodiment, the cord reinforcement extends at least through one of the lower legs, the intersection, and at least one of the upper legs. By extending the (same) cord reinforcement through these two legs and the intersection, particularly durable spokes can be provided.
[0040] In yet another embodiment, the polymer composition layer is provided as an overmolded sleeve that circumferentially surrounds each mold insert.
[0041] In yet another embodiment, at least one further mold member optionally has an essentially hexagonal cross-section to define the adjacent outer profiles of two adjacent spokes. Optionally, the further mold member has curved edges and / or corners.
[0042] In a third aspect of the present invention, the present invention relates to a method of manufacturing a non-pneumatic tire having a circumferential tread band on the outer radius (optionally having one or more of a radially outer tread portion and a shear band on the inner radius), a hub portion on the inner radius, and a circumferential support structure for supporting the circumferential tread band on the outer radius on the hub portion on the inner radius. The support structure has a circumferential radially outer ring portion (adjacent to the tread band), a circumferential radially inner ring portion (adjacent to the hub portion), and a plurality of spokes provided along the circumferential direction, preferably arranged and / or extending between the radially outer ring portion and the radially inner ring portion so as to support the radially outer ring portion on the radially inner ring portion. The method includes a step of preparing a mold for forming at least a circumferential segment or sector of the circumferential support structure, the mold having a radially outer mold ring member for forming the radially outer side of at least a circumferential segment or sector of the radially outer ring portion, a radially inner mold ring member for forming the radially inner side of at least a circumferential segment or sector of the radially inner ring portion, and a mold insert or member for forming the spokes of the plurality of spokes between the mold ring members, and most of the mold insert and / or member being at least partially covered by a polymer composition layer. The method further includes a step of arranging a cord reinforcement for reinforcing and / or connecting a plurality of spokes provided along the circumferential direction to be formed on the polymer composition layer (or at least a part thereof), and a step of injection molding another polymer composition on the cord reinforcement and the polymer composition layer to enclose the cord reinforcement with the other polymer composition and the polymer composition layer.
[0043] Thus, the whole and / or the circumferential sector of the circumferential support structure having a plurality of cord-reinforced spokes can be manufactured. Such a manufacturing process can be carried out in mass production and / or can be carried out cost-effectively.
[0044] In one embodiment, the cord reinforcement extends through a plurality of circumferentially adjacent spokes and preferably extends from one circumferential end of a sector of the support structure to the other circumferential end of the formed support structure sector.
[0045] In another embodiment, the cord reinforcement, or cord reinforcements, are disposed on a polymer composition layer within an assembled mold. Alternatively, the cord reinforcement(s) are disposed on a polymer composition layer on a mold insert, and then the mold insert is optionally inserted into a radially outer mold ring member and a radially inner mold ring member.
[0046] In yet another embodiment, the intersection is disposed closer to the hub in the radial direction than the radially outer ring portion and / or the radially inner leg is shorter than the radially outer leg.
[0047] In yet another embodiment, one or more spokes include, or have, one or more cross-sections of an X-shape, V-shape, C-shape, I-shape, H-shape, O-shape, S-shape, Y-shape, half-X shape, and one or more of the bent and folded shapes / morphologies of the aforementioned shapes in a plane parallel to the equatorial plane of the tire. Preferably, the shape is an X-shape such as a straight or curved X-shape. Another preferred shape is, in particular, a half-X shape corresponding to an X-shape that is essentially cut radially. Shapes such as an angled bracket shape or a chevron shape can also be mentioned, where the bend is not necessarily at the center of the shape in the radial direction.
[0048] Note that the aspects described above, and the embodiments and / or features referred to herein, can be combined with each other.
[0049] FIG. 1 shows a non-pneumatic tire 100 according to the present invention, i.e., a preferred embodiment of the non-pneumatic tire 100 manufactured by an embodiment of the method according to the present invention. The tire 100 has a tread band 110 having a radially outer tread portion 111 and a radially inner shear band 112, a radially inner hub portion 160, and a support structure 140 that supports the tread band 110 on the hub portion 160. Further, the support structure 140 extends in the circumferential direction about the axis of the tire 100 and has a plurality of spokes 130 along the circumferential direction. In the present embodiment, the spokes 130 are bent, i.e., curved, in an X shape. Such a shear band 112 is known to those skilled in the art of non-pneumatic tires and typically includes a plurality of laminated rubber composition layers extending in the circumferential direction. At least a part of such a layer is typically cord-reinforced.
[0050] Figure 2 shows a schematic cross-section of a spoke 130 code-reinforced by a cord 150. The spoke 130 has a pair of radially inner legs 132, a pair of radially outer legs 131, and an intersection 133 connecting the pair of legs 131, 132. Further, the illustrated spoke 130 has a radially inner head 137 and a radially outer foot 136. As shown, each pair of legs 131, 132 may be connected by respective connecting portions 134, 135 at their respective feet 136 or heads 137. As seen in Figure 2, the cord 150 extends into the spoke 130 in a zigzag pattern without protruding from the surface of the spoke. That is, the cord 150 is preferably completely covered by the polymer composition of the spoke 130, including a thermoplastic elastomer or rubber composition (such as a thermoplastic polyester elastomer). In particular, the cord 150 is wound through the spoke 130 between the radially inner head 137 and the radially outer foot 136. In another embodiment not shown, the same cord or cord reinforcement tape may be wound multiple times through the same spoke, for example, between its head and foot. As another option, multiple cords or cord reinforcement tapes may extend through the spoke. Additionally, or alternatively, as another option, it is also conceivable to have one or more cords, one or more cord reinforcement tapes, or one or more fabrics having cords extending through multiple adjacent spokes.
[0051] In a plurality of embodiments and / or drawings herein, for better orientation, a circumferential direction c, an axial direction a, and a radial direction r are shown. The circumferential direction c is perpendicular to the axial direction a. The same applies to the radial direction r. The axial direction a is parallel to the rotation axis of the tire. Such directions referred to in this specification are not necessarily limited to a specific orientation of a given direction unless otherwise specified in this specification.
[0052] FIG. 3 shows another embodiment of an X-shaped spoke 230, i.e., a spoke 230 having an X-shaped cross section, the spoke 230 having a pair of linear radially inner legs 232 and a pair of linear radially outer legs 231 connected thereto by intersections 233, and having a cord 250 wound between the radially inner head 237 and the radially outer foot 236 of the spoke 230. The radially inner ends of the legs 232 are connected by a radially inner connection 235, and the radially outer ends of the spokes 231 are connected by a radially outer connection 234. Also in this case, the cord 250 is completely enclosed within the material of the spoke 230. That is, as shown in this cross section, the cord 250 is not visible from the surface of the spoke 230. It should be noted that the pair of radially inner legs can also be described as a pair of radially upper legs, and the pair of radially outer legs can be described as a pair of radially lower legs, respectively. In this embodiment, the cord 250 passes through each of the legs 231, 232 of the spoke 230.
[0053] FIG. 4 shows method steps 10, 20, 30, 40 for manufacturing mold members, in particular mold inserts 1, 3, for manufacturing the spoke 230 already shown in FIG. 3. In step 10, two mold inserts 1, 3 each having a prismatic shape with a cross-section essentially triangular in shape are provided. In step 20, these mold inserts 1, 3 are placed or attached to respective mold members 2, 4, which each accommodate one of the respective mold inserts 1, 3 and have mold cavities 7, 8 that form a gap between the walls of the respective mold inserts 1, 3 and the respective mold members 2, 4. In a further method step 30, the gaps formed between the mold inserts 1, 3 and the corresponding mold members 2, 4 are filled with a polymer composition. In particular, the polymer composition is injection molded into the gaps to form one of the respective polymer composition layers 11, 13. Preferably, the polymer composition is a thermoplastic polyester elastomer or a rubber composition. Thereafter, in step 40, the mold inserts 1, 3 are removed from the mold members 2, 4 (or vice versa), whereby each mold insert 1, 3 is covered with a polymer composition layer 11, 13.
[0054] As further shown in method step 50, according to the embodiment of FIG. 5, the mold inserts 1, 3, preferably manufactured by the method steps shown in FIG. 4, are arranged overlapping each other such that two of their edges face each other. Further, the inserts 1, 3 still support the polymer composition layers 11, 13. The cord 250 crosses the gap between both inserts 1, 3 and is wound around these layers 11, 13 covering the inserts 1, 3. In a further method step 60, the mold inserts 1, 3 covered with the polymer composition layers 11, 13 and supporting the cord 250 are inserted into a mold member 6 that defines the outer shape of the X-shaped spokes to be molded. That is, the mold member 6 has a mold cavity 5 having the outer shape of the spokes 230 to be molded. In step 70, the gap between the mold member 6 and the polymer composition layers 11, 13 and the cord 250 is filled and / or injection molded with a second polymer composition flowing into the gap, and this second polymer composition is, in this non-limiting embodiment, the same as the polymer composition forming the first polymer composition layers 11, 13. Thus, in step 70, the spokes 230 with the cord 250 embedded, i.e., enclosed or encapsulated, in the polymer composition are molded or formed. In step 80, for example after cooling, the spokes 230 are removed from the mold member 6. Further, the inserts 1, 3 are also separated from the first polymer composition layer integrated with the spokes 230 and are specifically pulled out.
[0055] In the embodiments shown in FIGS. 3 and 5, a spoke 230 is provided with a cord 250 wound between the head and the foot of the spoke 230. Preferably, it is also possible for the cord to be wound a plurality of times between the head and the foot of such a spoke. In the embodiment of FIG. 6, an embodiment of a manufacturing method is shown that provides two mold inserts 1', 3' each covered by a respective polymer composition layer 11', 13', and a cord 250' is wound a plurality of times between the head and the foot of the spoke to be molded (i.e., disposed on the polymer composition layers 11', 13'). For example, both mold inserts 1', 3' are held in place, the cord 250' is wound around the inserts 1', 3' covered with the polymer composition layers 11', 13', and these mold inserts 1', 3' (which can also be referred to as mold members) can be inserted into a cavity 5' of a complementary or corresponding mold member 6' that defines the outer shape of the spoke to be molded. Providing the cord 250' wound a plurality of times through the spoke helps to provide a more durable spoke. Further, by providing the cord 250' on the polymer composition layers 11', 13', it is possible to prevent the cord 250' from being exposed on the surface of the spoke after demolding.
[0056] FIG. 7 shows another preferred option according to a preferred embodiment of the present invention, where a mold member or mold insert 3'' has a polymer composition layer 13'' covering the outer surface of the mold insert 3''. In addition to the structure of the mold inserts similar to those already shown in the foregoing figures, the mold insert 3'' according to FIG. 7 preferably has a plurality of parallel grooves 23''. These grooves 23'' can be used to dispose one or more cords within the grooves 23'', i.e., to dispose one or more segments of such one or more cords. Thereby, the position of the cord within the spoke to be molded can be controlled even better. In particular, the lateral movement of the cord with respect to the extension of the grooves 23'' can be restricted.
[0057] FIG. 8 shows a circumferential segment or sector of the support structure 340, which circumferential segment or sector has an inner circumferential ring portion (i.e., segment or sector) 345 and an outer circumferential ring portion (i.e., segment or sector) 344 in the radial direction, and these are connected by a plurality of spokes 330, for example, in this case, six spokes 330 each having an X-shaped cross section. It is also possible to provide a complete circumferential support structure for a non-pneumatic tire by combining or arranging a plurality of such sectors 340 in the circumferential direction.
[0058] FIG. 9 shows an embodiment of a mold for manufacturing the sector of the support structure 340 already shown in FIG. 8. The non-limiting embodiment of the mold shown in FIG. 9 has a plurality of mold members or inserts 301, 303, 307 covered by respective polymer composition layers 311, 313, 317. Further, these mold members 301, 303, 307 are shown in a state of being attached to a mold cavity 305 formed by one or more mold members 308, 309. For simplicity, the mold members 308, 309 are shown in FIG. 9 as being integrally formed, but may have or consist of a plurality of separate mold members forming the mold cavity 305. In particular, the inner surface of the mold member 308 facing the mold cavity 305 is adapted to form or mold the inner radial side of the ring portion 345 to be molded. The mold member 309 is adapted to form or mold the outer radial side of the outer radial ring portion 344 to be molded. According to this embodiment of the present invention, the mold members 301, 303, 307 are each covered by a polymer composition layer. However, depending on, for example, the desired way of winding the cords around these members, it is also possible that not all of them are covered by a polymer composition layer. In addition, alternatively or instead, in another option, the surfaces of one or more mold members 308, 309 are also covered by a polymer composition layer (not shown in FIG. 9).
[0059] Similar to the embodiment shown in FIG. 5, it is possible to wind at least one cord, or for example a cord reinforcing tape, around one or more mold inserts 301, 303. There are various options for installing or disposing one or more cord reinforcements on the mold member, and some of them are further shown in FIGS. 10 and 11.
[0060] FIG. 10 shows a schematic cross-section of the support structure already shown in FIG. 8, molded using the mold shown in FIG. 9. According to the embodiment of FIG. 10, two cords 350, 350' are wound multiple times between the radially inner ring portion 345 and the radially outer ring portion 344. Each cord 350, 350' extends through each spoke, specifically through one radially inner leg, the intersection of each spoke 330, and one radially outer leg. Both cords 350, 350' intersect at the intersection of the spokes 330. The cords 350, 350' wound in such a pattern provide a very durable sector of the support structure 340. Further, the cords 350, 350' are completely enclosed in the polymer composition of the spokes 330. Optionally, the cords 350, 350' are wound through a complete circumferential ring portion (not shown). Preferably, the cords 350, 350' are axially spaced from each other at least at the intersection of the spokes 330. Similarly, in another embodiment (not explicitly shown), one or more cord reinforcing tapes may be wound within a sector of the support structure, as shown for the cords in FIG. 10.
[0061] FIG. 11 shows another schematic cross-section of a sector of the support structure, which sector is similar to that of FIGS. 8 and 10 but has a different preferred winding pattern and number of cords. In particular, the sector 440 of the illustrated support structure has a radially inner ring portion 445 and a radially outer ring portion 444, which are connected to each other by a plurality of spokes 430, and the plurality of spokes 430 are arranged along the circumferential direction so as to support the radially outer ring portion 444 on the radially inner ring portion 445. In contrast to the previously described embodiments, the embodiment of FIG. 11 has seven separate cords 450, 451, 452, 453, 454, 455, 456. Each cord 451, 452, 453, 454, 455 connects two circumferentially adjacent spokes 430 to each other. In particular, in this non-limiting embodiment, such a cord, such as cord 451 for example, may be wound so as to pass through one leg adjacent to the radially outer side of the spoke from the radially outer / inner ring portion, through the intersection of the spokes, and further into the radially inner / outer leg of the same spoke and into the radially inner / outer ring portion. From there, the same cord may further enter the radially inner / outer legs of the adjacent spokes, further pass through their intersection, pass through the radially outer / inner legs of the same spoke, and finally return to the radially outer / inner ring portion, but the two ends of the cord are optionally opposed to each other. It should be noted that such a cord, such as cord 451 for example, can be wound axially multiple times through the sector of the support structure so as to further reinforce the two adjacent spokes 430, especially axially. Also, in another embodiment, it is possible to use a cord reinforcing tape instead of the cords 450, 451, 452, 453, 454, 455, 456.
[0062] Although not shown in the embodiments of this specification, in another option, a plurality of circumferential spoke rows, such as two rows, three rows, or four rows, are provided side by side axially. For each row, the circumferential position of such spokes may be the same as that of the adjacent row or may be circumferentially offset.
[0063] The mold, mold insert, and / or mold member are preferably composed of one or more heat-resistant materials having a melting point higher than 200°C, preferably higher than 300°C. Plastic, ceramic, or metal materials are non-limiting examples of such mold materials.
[0064] In summary, the present invention provides an improved manufacturing method for a cord-reinforced support structure for a non-pneumatic tire and / or its cord-reinforced spoke. The method, and optionally its embodiments, provide an efficient way to control the positioning of the cord reinforcement or cord and / or can contribute to preventing the cord reinforcement from appearing on the outer surface of the support structure or spoke. Further, such a method is suitable for cost-effective mass production of the support structure and / or spoke.
[0065] In light of the description provided herein, variations in the present invention are possible. For the purpose of illustrating the present invention, specific representative embodiments and details are shown, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the present invention. Therefore, it is to be understood that changes can be made in the specific embodiments described within the full intended scope of the present invention as defined by the following appended claims.
Claims
1. A method for manufacturing a support structure for a non-pneumatic tire having at least one cord-reinforced polymer composition spoke, comprising: providing a first mold member at least partially covered by a first polymer composition layer; placing at least one cord reinforcement on the first polymer composition layer; overmolding a second polymer composition layer on the first polymer composition layer and encapsulating the cord reinforcement between the first polymer composition layer and the second polymer composition layer to obtain at least a part of the cord-reinforced polymer composition spoke.
2. The method according to claim 1, wherein the first polymer composition layer has at least one groove, and the cord reinforcement is disposed on the first polymer composition layer within the groove.
3. The first mold member is a mold insert, and the method further comprises: providing at least one second mold member that forms a gap between the first polymer composition layer on the mold insert and the second mold member; the step of overmolding the second polymer composition layer includes injecting the second polymer composition into the gap to form the second polymer composition layer.
4. The method according to claim 1, wherein the first mold member is at least partially encapsulated by the first polymer composition layer.
5. The method according to claim 4, wherein the first mold member essentially has a prismatic shape with three circumferentially adjacent sides encapsulated by the first polymer composition layer.
6. The method according to claim 1, wherein the first polymer composition and the second polymer composition include one or more of an elastomer composition and a thermoplastic polymer.
7. The method according to claim 1, wherein the cord reinforcement has at least one cord including one or more of a fiber material, a glass fiber material, a carbon fiber material, a boron fiber material, a basalt fiber material, a plant-derived material, and combinations of these materials.
8. The method according to claim 1, wherein the first polymer composition layer is solid when the cord reinforcement is placed on the first polymer composition layer.
9. The first mold member essentially has a prismatic shape with three circumferentially adjacent sides encapsulated by the first polymer composition layer, and the method further comprises: A step of preparing yet another mold member that essentially has a prismatic shape in which three side surfaces adjacent in the circumferential direction are wrapped by yet another polymer composition layer, wherein the first mold member and the yet another mold member are arranged such that their edges face each other and are parallel to each other, and a step of preparing yet another mold member. The method according to claim 1, further comprising a step of arranging a cord reinforcing material on at least one side surface of the first mold member wrapped with the first polymer composition layer and at least one side surface of the yet another mold member wrapped with the yet another polymer composition layer.
10. The method according to claim 1, wherein the step of preparing the first mold member covered with the first polymer composition layer includes a sub-step of overmolding the first polymer composition layer on the first mold member.
11. The method according to claim 1, wherein the cord reinforcing material is a cord, and a plurality of portions of the cord arranged at intervals along the cord are arranged on the first polymer composition layer.
12. The method according to claim 11, wherein the portions of the cord arranged on the first polymer composition layer are arranged side by side on the first polymer composition layer.
13. The method according to claim 12, wherein the portions arranged side by side are spaced apart from each other.
14. The method according to claim 1, wherein the spoke essentially has an X-shaped cross-section.
15. The spoke has an essentially X-shaped cross-section having a pair of upper legs, a pair of lower legs, and an intersection connecting the pair of upper legs and the pair of lower legs. The first mold member is arranged between the upper legs to partially define the boundary of the pair of upper legs on the inner side, and the yet another mold member is arranged between the lower legs to partially define the boundary of the pair of lower legs on the inner side. The method according to claim 9, further comprising providing one or more additional mold members opposite to the first mold member and the yet another mold member to define the boundaries of the upper legs and the lower legs on the outer side.
16. The method according to claim 1, further comprising a step of removing the first mold member after overmolding.
17. A method of manufacturing a support structure for a non-pneumatic tire having at least one X-shaped code-reinforced polymer composition spoke, said X-shaped spoke having a pair of upper legs and a pair of lower legs connected by an intersection. A) Providing a mold having mold members, said mold members comprising: i) a prismatic first mold insert for defining an inner surface between the upper legs of said X-shaped spoke; ii) a prismatic second mold insert for defining an inner surface between the lower legs of said X-shaped spoke; and iii) at least one further mold member for defining an outer surface essentially opposite to said inner surface defined by said first and second mold inserts of said X-shaped spoke, at least one of said mold members being at least partially covered by at least one polymer composition layer. B) Placing a cord reinforcement on said polymer composition layer. C) Injection molding a further polymer composition over said cord reinforcement and said polymer composition layer to confine said cord reinforcement with said further polymer composition and said polymer composition layer.
18. The method according to claim 17, wherein at least a part of said polymer composition layer has at least one groove extending essentially parallel to and along the legs of said spoke, and said cord reinforcement is placed on said polymer composition layer within said groove so as to restrict movement of said cord reinforcement perpendicular to said groove.
19. The method according to claim 17, wherein said polymer composition layer is provided as a sleeve overmolded on each of said mold inserts, surrounding each of said mold inserts in the circumferential direction.
20. A method of manufacturing a non-pneumatic tire having a circumferential tread band on the outer radial side, a hub portion on the inner radial side, and a circumferential support structure for supporting said circumferential tread band on the outer radial side on said hub portion on the inner radial side, said support structure having a circumferential outer radial ring portion, a circumferential inner radial ring portion, and a plurality of cord-reinforced polymer composition spokes provided along the circumferential direction and arranged between said outer radial ring portion and said inner radial ring portion. A step of preparing a mold for molding at least a circumferential sector of the circumferential support structure, the mold having a radially outer mold ring member for molding the radially outer side of at least a circumferential segment of the radially outer ring portion, a radially inner mold ring member for molding the radially inner side of at least a circumferential segment of the radially inner ring portion, and a mold insert for molding the spokes of the plurality of spokes between the mold ring members, and a majority of the mold insert being covered by a polymer composition layer; the step of preparing the mold A step of disposing a cord reinforcing material for reinforcing and connecting a plurality of spokes provided along the circumferential direction to be molded on at least a part of the polymer composition layer A method including a step of injection molding still another polymer composition onto the cord reinforcing material and the polymer composition layer, and confining the cord reinforcing material with the still another polymer composition and the polymer composition layer