JP2022034664A - Method for manufacturing airless tire - Google Patents

Abstract

To provide a method for manufacturing an airless tire which suppresses peeling between a tread ring and a spoke part over a long period of time, and can improve durability.SOLUTION: A method for manufacturing an airless tire 1 including a tread ring 2 that is an annular rubber member, a metal hub 3 arranged inside in a tire radial direction of the tread ring 2, and a spoke part 4 for connecting the tread ring 2 and the hub 3, includes: a step of preparing the tread ring 2 and the hub 3; a step of arranging the hub 3 in a first mold; a step of injecting a first thermoplastic polymer material to the periphery of the hub 3 in the first mold, and molding a spoke composite body obtained by integrally curing the hub 3 and the spoke part 4 therein; a step of taking out the spoke composite body from the first mold, and contracting the spoke part 4; and a step of joining the tread ring 2 to the spoke composite body in which the spoke part 4 has been contracted.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing an airless tire.

The following Patent Document 1 describes an airless tire. The airless tire comprises a cylindrical tread ring with a tread, a metal hub fixed to the axle, and a plurality of spokes extending and connecting radially between them.

Japanese Unexamined Patent Publication No. 2018-94825

A typical method for manufacturing an airless tire as described above is as follows. First, the tread ring and hub are prepared. Next, these tread rings and hubs are arranged in a mold for forming the spoke portions. Next, a resin is poured between the tread ring and the hub in the mold to form a spoke portion. As a result, an airless tire in which the tread ring, the hub, and the spoke portions are integrated with each other can be obtained.

However, the airless tire manufactured by the conventional manufacturing method has a problem that peeling easily occurs at the joint portion between the spoke portion and the tread ring portion. As a result of diligent research on such a problem, the inventors have found that the so-called molding shrinkage that occurs in the spoke portion after molding promotes the peeling at the joint portion.

The present invention has been devised in view of the above circumstances, and is a method for manufacturing an airless tire capable of suppressing peeling between the tread ring and the spoke portion for a long period of time and improving durability. The main issue is to provide.

In the present invention, a tread ring which is an annular rubber member having a ground contact surface, a metal hub arranged inside the tread ring in the tire radial direction, and a spoke portion connecting the tread ring and the hub are provided. A method for manufacturing an airless tire provided, the step of preparing the tread ring and the hub, the step of arranging the hub in the first mold, and the surrounding of the hub in the first mold. A step of injecting a first thermoplastic polymer material to form a spoke composite in which the hub and the spoke portion are integrally cured, and a step of taking out the spoke composite from the first mold and shrinking the spoke portion. It is a method of manufacturing an airless tire including a step of joining the tread ring and the spoke composite having finished shrinking of the spoke portion.

In another aspect of the present invention, a step of arranging the tread ring and the spoke composite having finished contraction of the spoke portion in the second mold, and the tread ring and the tread ring in the second mold are described. A step of injecting a second thermoplastic polymer material into the gap between the spoke composite and the spoke composite to integrally cure the tread ring and the spoke composite can be included.

In another aspect of the present invention, the first thermoplastic polymer material and the second thermoplastic polymer material may be a polyurethane-based, polyester-based or polyamide-based thermoplastic resin or thermoplastic elastomer.

In another aspect of the present invention, the first thermoplastic polymer material and the second thermoplastic polymer material can contain the same polymer material.

In another aspect of the present invention, the first thermoplastic polymer material and the second thermoplastic polymer material may be the same material.

In another aspect of the present invention, at least one of the first thermoplastic polymer material and the second thermoplastic polymer material may be a polyamide-based polymer material.

In another aspect of the present invention, the first mold is connected to a first cavity for arranging the hub, and is connected to the first cavity and is surrounded by the hub arranged in the first cavity. A second cavity for forming the spoke portion can be provided.

In another aspect of the present invention, the second mold has a third cavity for arranging the tread ring and the spoke composite inside the tread ring arranged in the third cavity in the radial direction of the tire. A fourth cavity for arranging and a fifth cavity for forming a connecting portion connecting the tread ring and the spoke composite between the third cavity and the fourth cavity may be provided. can.

By adopting the above process, the present invention can suppress peeling between the tread ring and the spoke portion for a long period of time, and thus can manufacture an airless tire having excellent durability.

It is a side view of the airless tire manufactured by the manufacturing method of this embodiment. It is a perspective view of the airless tire manufactured by the manufacturing method of this embodiment. It is an enlarged sectional view of the main part of FIG. It is a side view of the spoke complex of this embodiment. It is a top view of the 1st mold of this embodiment. It is a top view of the state in which the 1st thermoplastic polymer material is injected into the 1st mold in which a hub is arranged. It is a top view which shows the contraction of the spoke complex of this embodiment. It is a top view of the 2nd mold of this embodiment. It is a top view of the 2nd mold in which the tread ring and the spoke composite are arranged. It is a top view which shows the state which the 2nd thermoplastic polymer material was injected into the 2nd mold which arranged the tread ring and the spoke composite.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

It must be understood that the drawings contain exaggerated expressions and expressions that differ from the dimensional ratio of the actual structure in order to aid the understanding of the present invention. Further, when there are a plurality of embodiments, the same or common elements are designated by the same reference numerals throughout the specification, and duplicate explanations are omitted. Furthermore, the specific configurations shown in the embodiments and drawings are for understanding the contents of the present invention, and the present invention is not limited to the specific configurations shown.

[Basic structure of airless tires]
Prior to the description of the manufacturing method of the present invention, first, the basic structure of the airless tire will be described.

FIG. 1 is a side view of an airless tire 1 manufactured by the manufacturing method of the present embodiment, FIG. 2 is a perspective view thereof, and FIG. 3 is an enlarged cross-sectional view of a main part of FIG. As shown in FIGS. 1 to 3, the airless tire 1 includes a tread ring 2, a hub 3 arranged inside the tread ring 2 in the radial direction of the tire, and a spoke portion 4 connecting the tread ring 2 and the hub 3.

[Tread ring]
The tread ring 2 is an annular rubber member, and is formed of, for example, vulcanized rubber. The outer surface of the tread ring 2 in the radial direction of the tire is formed as a ground contact surface 2a for contacting the ground. Various drainage grooves (not shown) may be formed on the ground plane 2a. Further, a spoke portion 4 described later is joined to the inner peripheral surface 2b of the tread ring 2 in the tire radial direction.

In a preferred embodiment, the tread ring 2 is internally provided with a reinforcing cord layer 2c, as shown in FIG. The reinforcing cord layer 2c is composed of, for example, a layer in which a plurality of organic fiber cords or steel cords are oriented in a predetermined direction. Such a reinforcing cord layer 2c is useful for increasing the rigidity of the tread ring 2 in the tire circumferential direction and / or the tire axial direction, and improving steering stability. Further, a resin material may be partially added or compounded to the tread ring 2.

[Hub]
The hub 3 is for fixing the axle and is made of metal. The hub 3 integrally includes, for example, a disc portion 3a and a cylindrical portion 3b formed on the outer side in the radial direction of the tire. The disc portion 3a is arranged concentrically with the tread ring 2. For example, a center bore 3c, a mounting hole 3d, and the like are formed in the disk portion 3a.

[Spokes]
The spoke portion 4 is formed between the tread ring 2 and the hub 3 and integrally connects them.

The spoke portion 4 is made of a resin material. Since the spoke portion 4 has a function of absorbing vibration during tire running and improving ride comfort performance, it is desirable that the resin material has, for example, a strength capable of sufficiently exerting a load bearing capacity. The spoke portion 4 of the present embodiment is made of a thermoplastic polymer material such as a thermoplastic resin or a thermoplastic elastomer. As the thermoplastic resin and the thermoplastic elastomer, for example, polyurethane-based, polyester-based, polyamide-based, polyolefin-based, polystyrene-based, and mixtures thereof are used. In consideration of heat resistance and strength, a polyurethane-based, polyester-based, polyamide-based, and a mixture thereof, a thermoplastic resin or a thermoplastic elastomer is desirable.

The spoke portion 4 of the present embodiment integrally includes, for example, an outer ring portion 4a on the outer side in the radial direction of the tire, an inner ring portion 4b on the inner side in the radial direction of the tire, and a plurality of spoke elements 4c.

The outer ring portion 4a is, for example, an annular body joined to the inner peripheral surface 2b of the tread ring 2.

The inner ring portion 4b is an annular body joined to the outer peripheral surface of the hub 3 (more specifically, the outer peripheral surface of the cylindrical portion 3b).

Each spoke element 4c extends in the radial direction of the tire and connects the outer ring portion 4a and the inner ring portion 4b to each other. Each spoke element 4c can, for example, bend during traveling to alleviate the impact input to the tread ring 2. The shape of the spoke element 4c is not limited to the illustrated embodiment, and various types such as those extending in a zigzag shape in the radial direction or the circumferential direction of the tire and those extending in a mesh shape in the tire circumferential cross section are used. Aspects are adopted.

[Manufacturing method of airless tires]
Next, a method for manufacturing the airless tire 1 will be described.

[Preparation of tread ring and hub]
The manufacturing method of the present embodiment includes a step of preparing the tread ring 2 and the hub 3. The tread ring 2 can be obtained, for example, by molding an unvulcanized rubber material, a cord material, or the like into a predetermined shape and vulcanizing it with a mold or the like according to the custom. Further, the hub 3 is manufactured by various methods such as casting, forging, and cutting.

[Manufacturing of spoke complex]
As shown in FIG. 4, the manufacturing method of the present embodiment includes a step of forming a spoke complex 7 in which a hub 3 and a spoke portion 4 are integrally cured. The spoke complex 7 is formed, for example, by using the first mold 10 as shown in FIG.

FIG. 5 shows a plan view of the first mold 10. The first mold 10 includes, for example, a lower mold 10A and an upper mold 10B that can move in the vertical direction relative to the lower mold 10A. FIG. 5 shows the upper die 10B and the lower die 10A in a closed state, and shows the lower side of the mating surface 11 thereof, and the upper die 10B appears as a cross section.

As shown in FIG. 5, the lower mold 10A of the first mold 10 is formed with a cavity 20 formed of a columnar recess. The cavity 20 includes an essentially circular bottom surface 12 and an inner peripheral surface 13 rising from the bottom surface 12, the upper portion thereof being closed by the upper mold 10B.

Further, the cavity 20 includes a first cavity 21 and a second cavity 22. In FIG. 5, the boundary between the first cavity 21 and the second cavity 22 is shown by a virtual line to help understanding these.

The first cavity 21 is a space for arranging a hub 3 prepared in advance. The first cavity 21 is provided with protruding shafts 14 and 15 extending upward from the bottom surface 12. The hub 3 is arranged in the first cavity 21 with its axis in the vertical direction, and substantially fills the first cavity 21. In other words, the outer peripheral surface of the hub 3 essentially defines the boundary between the first cavity 21 and the second cavity 22.

Further, the center bore 3c and the mounting hole 3d of the hub 3 are inserted into the protruding shafts 14 and 15 of the first cavity 21, respectively. This helps to accurately align the hub 3 with the first cavity 21.

The second cavity 22 is a space for forming the spoke portion 4 around the hub 3 arranged in the first cavity 21. The second cavity 22 is connected to the outside of the first cavity 21 and extends in an annular shape. The second cavity 22 of the present embodiment includes a bottom surface 12 of the lower mold 10A, a protrusion 16 extending upward from the bottom surface 12, an inner peripheral surface 13 of the cavity 20, an outer peripheral surface of the hub 3 arranged in the first cavity 21, and the outer peripheral surface of the hub 3. It is defined by the upper mold 10B.

Further, the upper mold 10B includes a plurality of protrusions 17 for forming spokes extending downward. When the lower mold 10A and the upper mold 10B are closed, these protrusions 17 enter between the protrusions 16 and 16 of the lower mold 10A and define the second cavity 22. Although not shown, the second cavity 22 communicates with a gate for injecting a thermoplastic polymer material into the second cavity 22.

An annular gap for forming the outer ring portion 4a of the spoke portion 4 is formed between the protrusions 16 and 17 and the inner peripheral surface 13 of the first cavity 21. Similarly, an annular gap for forming the inner ring portion 4b of the spoke portion 4 is formed between the protrusions 16 and 17 and the outer peripheral surface of the hub 3. Further, a gap for forming the spoke element 4c is formed between the plurality of protrusions 16 and 17 alternately arranged in the circumferential direction.

The preferred procedure for forming the spoke complex 7 using the first mold 10 configured as described above is as follows.

For example, a base treatment such as shot blasting and / or an adhesive is applied to the outer peripheral surface of the hub 3. This helps to increase the adhesive force between the hub 3 and the spoke portion 4.

Next, the hub 3 is arranged in the first mold 10. Specifically, the first mold 10 is opened, and the hub 3 is arranged in the first cavity 21 of the lower mold 10A.

Next, the upper mold 10B is fitted to the lower mold 10A, and the first mold 10 is closed.

Next, as shown in FIG. 6, the molten first thermoplastic polymer material 8 is injected, that is, pressure-injected into the second cavity 22 through a gate (not shown). As a result, the second cavity 22 around the hub 3 is filled with the first thermoplastic polymer material 8. In addition, various injection devices may be adopted for this injection according to the custom.

Next, the first thermoplastic polymer material 8 is cooled and cured in the first mold 10 (cooling step). As a result, as shown in FIG. 4, a spoke complex 7 in which the hub 3 and the spoke portion 4 are integrally cured can be obtained.

[Spoke contraction]
The manufacturing method of the present embodiment includes a step of opening the first mold 10 and taking out the spoke complex 7 from the first mold 10 after the spoke portion 4 is cured. Further, as shown in FIG. 7, the manufacturing method of the present embodiment includes a step of shrinking the spoke portion 4 of the spoke complex 7 taken out.

After the first thermoplastic polymer material 8 is taken out from the mold, molding shrinkage of about several percent occurs. Therefore, the volume of the spoke portion 4 made of the first thermoplastic polymer material 8 also shrinks with the passage of time, for example, its outer diameter also shrinks (FIG. 7 shows before shrinkage for easy understanding). The outer diameter of is shown by a virtual line.) According to the experiments of the inventors, it was found that such molding shrinkage of the spoke portion 4 is one of the causes of premature peeling at the joint portion between the spoke portion and the tread ring of the airless tire so far. ..

In this embodiment, the spoke portion 4 is contracted in advance prior to joining to the tread ring 2. As a result, the internal stress of the spoke portion 4 (particularly, the stress at which the spoke element 4c tends to contract in the radial direction of the tire) is removed, and the joint strength with the tread ring 2 is improved. Specifically, the spoke complex 7 is left in a free state at room temperature (25 ° C. ± 3 ° C.), for example, until the spoke portions 4 have sufficiently undergone molding shrinkage. The degree of progress of shrinkage varies depending on conditions such as the structure of the spoke portion 4, the type of the first thermoplastic polymer material 8, and the injection temperature. Therefore, the leaving time can be appropriately set according to various conditions and also in consideration of productivity and the like. As an example of the leaving time, about 0.5 to 24 hours is desirable.

[Joining tread ring and spoke complex]
The present embodiment includes a step of joining the tread ring 2 and the spoke complex 7 which has finished shrinking the spoke portion 4. This step is performed in various embodiments. In the simplest aspect, the inner peripheral surface 2b of the tread ring 2 and the outer peripheral surface of the spoke complex 7 (the outer peripheral surface of the outer ring portion 4a of the spoke portion 4) are fixed via an adhesive. As a result, the airless tire 1 is manufactured.

In another aspect, the tread ring 2 and the spoke complex 7 which has finished shrinking of the spoke portion 4 can be joined by using the second mold 30 as shown in FIG. Hereinafter, this step will be specifically described.

[Placement of tread ring and spoke complex on the second mold]
FIG. 8 shows a plan view of the second mold 30. In this step, the tread ring 2 and the spoke complex 7 that has finished shrinking the spoke portion 4 are arranged in the second mold 30.

The second mold 30 includes, for example, a lower mold 30A and an upper mold (not shown) that can move in the vertical direction relative to the lower mold 30A. FIG. 8 shows the upper mold 30B and the upper mold in a closed state and below the mating surface thereof.

A cavity 40 formed of a columnar recess is formed in the lower mold 30A of the second mold 30. The cavity 40 includes an essentially circular bottom surface 41, an inner peripheral surface 42 rising from the bottom surface 41, the upper portion thereof being closed by an upper mold.

Further, the cavity 40 includes a third cavity 43, a fourth cavity 44, and a fifth cavity 45. In FIG. 8, each boundary of the third cavity 43, the fourth cavity 44, and the fifth cavity 45 is shown by a virtual line to help understanding these.

The third cavity 43 is an annular space for arranging the tread ring 2. In the present embodiment, the outer peripheral surface of the tread ring 2 is arranged so as to be substantially aligned with the inner peripheral surface 42 of the cavity 40. Therefore, in this state, the position corresponding to the inner peripheral surface of the tread ring 2 is the inner boundary of the third cavity 43 in the tire radial direction.

The fourth cavity 44 is a space for arranging the spoke complex 7. The fourth cavity 44 of the present embodiment is formed inside the third cavity in the radial direction of the tire. The fourth cavity 44 is provided with, for example, protruding shafts 31 and 32 extending upward from the bottom surface 41. The hub 3 of the spoke complex 7 is arranged in the fourth cavity 44 with its axis in the vertical direction. In other words, the outer peripheral surface of the spoke complex 7 essentially defines the outer boundary of the fourth cavity 44 in the tire radial direction.

The fifth cavity 45 is formed between the third cavity 43 and the fourth cavity 44. The fifth cavity 45 of the present embodiment is formed in an annular shape in the circumferential direction. The fifth cavity 45 is a space for forming a connecting portion (described later) for connecting the tread ring 2 and the spoke complex 7. A gate (not shown) for injecting the second thermoplastic resin communicates with the fifth cavity 45.

As shown in FIGS. 8 and 9, in the second mold 30, the tread ring 2 is arranged in the third cavity 43, and the spoke complex 7 is arranged in the fourth cavity 44, respectively. As a result, the spoke complex 7 is positioned inside the tread ring 2 in the tire radial direction in the second mold 30. Further, a gap continuous in the tire circumferential direction, that is, a fifth cavity 45 is formed between the tread ring 2 and the spoke complex 7. In a preferred embodiment, for example, the inner peripheral surface of the tread ring 2 may be previously coated with a surface treatment and / or an adhesive.

[Injection of second thermoplastic polymer material]
In the manufacturing method of the present embodiment, as shown in FIG. 10, the second thermoplastic polymer is formed in the gap between the tread ring 2 and the spoke composite 7 (that is, the fifth cavity 45) in the second mold 30. The step of injecting the material 9 and integrally curing the tread ring 2 and the spoke composite 7 is included. The second thermoplastic polymer material 9 filled in the fifth cavity 45 comes into contact with both the tread ring 2 and the spoke complex 7 and is cured in that state. As a result, the second thermoplastic polymer material 9 becomes a connecting portion 50 that integrally connects the tread ring 2 and the spoke complex 7. By curing the second thermoplastic polymer material 9, the airless tire 1 as shown in FIGS. 1 to 3 is formed.

In addition, in order to suppress deformation of each spoke element 4c of the spoke composite 7 due to the injection pressure of the second thermoplastic polymer material 9, for example, in order to hold the shape of the spoke element 4c in the fourth cavity 44. Various support members and the like may be provided (not shown).

[Removing airless tires]
After the above steps, the second mold 30 is opened and the airless tire 1 is taken out.
In the airless tire 1 manufactured as described above, the spoke portions 4 of the spoke composite 7 are joined to the tread ring 2 in a state where the spoke portions 4 have already been contracted. Therefore, in the airless tire 1 after molding, almost or no internal contraction force is generated in the spoke portions 4 in the free state. Therefore, the airless tire 1 of the present embodiment has a high joint strength between the spoke portion 4 and the tread ring 2, and peeling thereof is suppressed for a long period of time, and thus excellent durability is exhibited.

Here, a connecting portion 50 made of the second thermoplastic polymer material 9 is interposed between the spoke portion 4 and the tread ring 2, and molding shrinkage may occur in this connecting portion 50 as well. However, the volume of the connecting portion 50 is sufficiently smaller than that of the spoke portion 4, and the internal stress (internal contraction force) remaining in the connecting portion 50 causes peeling between the tread ring 2 and the spoke portion 4. Is small enough to have little effect and can be ignored. From this point of view, the thickness t of the connecting portion 50 in the tire radial direction is desired to be as small as possible, and therefore, for example, it is preferably 5 mm or less, more preferably 3 mm or less.

On the other hand, if the thickness t of the connecting portion 50 becomes excessively small, the bonding strength between the tread ring 2 and the spoke complex 7 may decrease, so the bonding strength is preferably 0.5 mm or more, more preferably 1 mm or more. Is desirable. The thickness of the connecting portion 50 can be adjusted by appropriately setting the radius of the inner peripheral surface 2b of the tread ring 2 and the radius of the outer peripheral surface of the spoke complex 7 in consideration of shrinkage.

The second thermoplastic polymer material 9 is not particularly limited, and for example, like the first thermoplastic polymer material 8, a polyurethane-based, polyester-based, or polyamide-based thermoplastic resin or thermoplastic elastomer can be used. Suitable. In a preferred embodiment, it is desirable that the first thermoplastic polymer material 8 constituting the spoke portion 4 and the second thermoplastic polymer material 9 constituting the connecting portion 50 include the same polymer material. As a result, the joint connection between the spoke portion 4 and the connecting portion 50 is further enhanced. In particular, it is particularly desirable that the first thermoplastic polymer material 8 and the second thermoplastic polymer material 9 are the same material (including additives and the like).

Further, it is desirable that at least one of the first thermoplastic polymer material 8 and the second thermoplastic polymer material 9 contains a polyamide-based thermoplastic resin or a thermoplastic elastomer. Since the polyamide-based resin or elastomer is excellent in adhesiveness, it is desirable in that the bond between the spoke portion 4 and the connecting portion 50 is further enhanced.

Further, it is desirable that the second thermoplastic polymer material is injected at the same temperature as or higher than the injection temperature of the first thermoplastic polymer material. This is because the surface of the first thermoplastic polymer material once cured is melted to some extent, and the bonding with the second thermoplastic polymer material becomes stronger.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned specific disclosure, and is various within the scope of the technical idea described in the claims. It can be changed and implemented.

Hereinafter, more specific and non-limiting examples of the present invention will be described.

Airless tires (tires corresponding to tire sizes 145 / 70R12) having the basic structure shown in FIGS. 1 to 3 were prototyped and their durability was evaluated. The method for manufacturing the airless tire of the embodiment is as follows.

A tread ring made of vulcanized rubber and a hub made of aluminum alloy were prepared. The surface of the tread ring is made of rubber, but an outer reinforcing cord layer and an inner reinforcing cord layer are arranged inside. The details are as follows.
<Outer reinforcement cord layer>
・ Number of plies: 2 ・ Reinforcement cord: Steel cord ・ Cord angle: +21 degrees / -21 degrees <Inner reinforcement cord layer>
・ Number of plies: 1 ・ Reinforcement cord: Steel cord ・ Cord angle: 0 degrees (spiral winding)
The tread ring was vulcanized at 170 ° C. for 20 minutes.

Next, an adhesive (trade name "Chemlock" manufactured by Lord Far East Corporation) was applied to the outer peripheral surface of the hub, and then the hub was placed in the first cavity of the first mold.

Next, in order to form the spoke portion in the second cavity of the first mold, the first thermoplastic polymer material (thermoplastic polyurethane resin) was injected at an injection temperature of about 220 ° C.

After curing the first thermoplastic polymer material, the spoke complex was taken out from the first mold. The spoke complex was cooled to room temperature (25 ° C.) in a free state so that the spoke portions could freely contract. After cooling, it was left for a while. The leaving time was set to 1 hour.

Next, an adhesive (trade name "Chemlock" manufactured by Lord Far East Corporation) was applied to the inner peripheral surface of the tread ring portion and placed in the third cavity of the second mold. Further, the spoke complex having finished shrinking the spoke portion was placed in the fourth cavity of the second mold. The second mold was adjusted so that a gap (fifth cavity) having a thickness of about 2 mm was continuous in the tire circumferential direction between the outer peripheral surface of the spoke complex and the inner peripheral surface of the tread ring.

Next, an airless tire was manufactured by injection molding the same thermoplastic polyurethane resin as the first thermoplastic polymer material as the second thermoplastic polymer material into the fifth cavity of the second mold and curing it.

Further, for comparison, a tread ring and a hub prepared in advance were placed in a mold, and thermoplastic urethane was injection-molded between them to integrally mold a spoke portion to manufacture an airless tire.

Then, 10 airless tires were manufactured for each of Examples and Comparative Examples, and durability tests were conducted on them. In the durability test, each tire was run under the conditions of a speed of 60 km / hr and a load of 2 kN using a drum tester. Then, the average value (N = 10) of the running time until the tire was damaged was measured.

As a result of the test, it was confirmed that the durability performance of the examples was improved by 180% as compared with the comparative examples.

1 Airless tire 2 Tread ring 2a Tread 3 Hub 4 Spokes 7 Spoke composite 8 1st thermoplastic polymer material 9 2nd thermoplastic polymer material 10 1st mold 20 1st mold cavity 21 1st cavity 22 2nd Cavity 30 2nd Mold 40 2nd Mold Cavity 43 3rd Cavity 44 4th Cavity 45 5th Cavity 50 Connecting Part

Claims (8)

An airless tire including a tread ring which is an annular rubber member having a contact patch, a metal hub arranged inside the tread ring in the radial direction of the tire, and a spoke portion connecting the tread ring and the hub. It is a manufacturing method of
The process of preparing the tread ring and the hub,
The process of arranging the hub in the first mold and
A step of injecting a first thermoplastic polymer material around the hub in the first mold to form a spoke composite in which the hub and the spoke portion are integrally cured.
A step of taking out the spoke complex from the first mold and shrinking the spoke portion,
A step of joining the tread ring and the spoke complex that has finished shrinking the spoke portions.
How to manufacture airless tires. A step of arranging the tread ring and the spoke complex having finished shrinking of the spoke portion in the second mold.
A step of injecting a second thermoplastic polymer material into a gap between the tread ring and the spoke composite in the second mold to integrally cure the tread ring and the spoke composite is included.
The method for manufacturing an airless tire according to claim 1. The method for producing an airless tire according to claim 2, wherein the first thermoplastic polymer material and the second thermoplastic polymer material are polyurethane-based, polyester-based, or polyamide-based thermoplastic resins or thermoplastic elastomers. The method for producing an airless tire according to claim 2 or 3, wherein the first thermoplastic polymer material and the second thermoplastic polymer material contain the same polymer material. The method for manufacturing an airless tire according to any one of claims 2 to 4, wherein the first thermoplastic polymer material and the second thermoplastic polymer material are the same material. The method for producing an airless tire according to any one of claims 2 to 5, wherein at least one of the first thermoplastic polymer material and the second thermoplastic polymer material is a polyamide-based polymer material. The first mold is a first cavity for arranging the hub, and a first cavity for forming the spoke portion around the hub arranged in the first cavity and connected to the first cavity. The method for manufacturing an airless tire according to any one of claims 1 to 6, further comprising two cavities. The second mold has a third cavity for arranging the tread ring and a fourth cavity for arranging the spoke composite inside the tread ring arranged in the third cavity in the tire radial direction. 1. Any one of claims 2 to 6, comprising a fifth cavity between the third cavity and the fourth cavity for forming a connecting portion connecting the tread ring and the spoke composite. The method for manufacturing an airless tire described in the section.

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