JP6834450B2 - How to manufacture airless tires - Google Patents

Description

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

Patent Document 1 below proposes an airless tire in which a cylindrical tread ring having a ground contact surface and a hub for fixing an axle are connected by spokes made of a thermosetting resin.

In the proposed airless tire, an adhesive is applied to the inner peripheral surface of the tread ring that has been vulcanized in advance in order to increase the adhesive strength between the tread ring and the spokes. After that, the tread ring and the hub coated with the adhesive are mounted in the casting mold, and the raw material liquid of the thermosetting resin for forming the spokes is injected and cured to form the spokes, the tread ring and the hub. Is integrated.

However, as a result of the experiment of the present inventor, it has been found that the adhesion between the spokes and the adhesive is insufficient depending on the temperature conditions at the time of casting, and the durability of the tire is lowered.

The reason for this is presumed to be as follows. The thermosetting resin and the adhesive exhibit a strong bonding force due to the adhesive reaction that occurs at the interface between them. However, this adhesive reaction proceeds at the same time as the curing of the thermosetting resin.

Therefore, for example, when the temperature of the tread ring is extremely lower than the temperature of the casting die, the temperature of the interface between the thermosetting resin and the adhesive is lowered by the tread ring. Therefore, the rate of the adhesion reaction at the interface becomes slower than the rate of curing of the thermosetting resin heated by the casting mold. As a result, it is presumed that the progress of the adhesive reaction is delayed, the bonding force at the interface becomes insufficient, and the durability of the tire is lowered.

International Publication WO2014 / 188912

Therefore, the present invention can increase the speed of the adhesive reaction at the interface between the thermosetting resin and the adhesive based on preheating the tread ring coated with the adhesive layer, and enhance the bonding force at the interface. The challenge is to provide a method for manufacturing airless tires that can improve the durability of tires.

The present invention includes a cylindrical tread ring having a ground plane, a hub for fixing an axle arranged radially inside the tread ring, and spokes made of a thermosetting resin connecting the tread ring and the hub. It ’s a method of manufacturing airless tires.
An adhesive application step of applying an adhesive to the inner peripheral surface of a vulcanized tread ring to form an adhesive layer,
An adhesive application step of applying an adhesive to the inner peripheral surface of the tread ring to form an adhesive layer,
The mounting process of mounting the tread ring coated with the adhesive layer and the hub in the casting mold, and
Casting molding that integrates the spokes, tread ring, and hub by injecting and curing the raw material liquid of the thermosetting resin into the casting mold and the space between the tread ring and the hub. Including the process
Prior to the mounting step, a preheating step of preheating the tread ring coated with the adhesive layer is performed.

In the method for manufacturing an airless tire according to the present invention, the preheating temperature Tr (° C.) of the tread ring in the preheating step has a relationship of the mold temperature T (° C.) of the casting die and the following formula (1). Is preferable.
T-10 ≤ Tr --- (1)

In the method for producing an airless tire according to the present invention, the thermosetting resin is preferably a urethane resin.

In the method for manufacturing an airless tire according to the present invention, the preheating temperature Tr (° C.) of the tread ring in the preheating step is preferably 150 ° C. or lower.

In the method for producing an airless tire according to the present invention, the thickness of the adhesive layer after drying is preferably 5 to 100 μm.

As described above, the present invention includes a preheating step of preheating the tread ring coated with the adhesive layer between the adhesive coating step and the mounting step. Therefore, it is possible to reduce the delay in the adhesion reaction rate at the interface between the thermosetting resin and the adhesive with respect to the curing rate of the thermosetting resin. As a result, at the interface, a sufficient bonding force due to the adhesive reaction can be sufficiently secured, and the durability of the tire can be improved.

It is a perspective view which shows an Example of the airless tire formed by the manufacturing method of the airless tire of this invention. It is a cross-sectional view of the meridian. It is sectional drawing which exaggerates the joint part of a tread ring, a spoke, and a hub. (A) to (D) are conceptual diagrams showing the arrangement state of the spoke plates in the case where the spoke portions are composed of a row of spoke plates in a plane. (A) to (D) are conceptual diagrams showing the state of the spoke plates in the case where the spoke portions are composed of the spoke plates extending continuously in the circumferential direction in a plane. It is a conceptual diagram which shows the manufacturing method of an airless tire.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIGS. 1 and 2, the airless tire 1 of the present embodiment includes a cylindrical tread ring 2 having a contact patch S, and an axle fixing hub 3 arranged inside the tread ring 2 in the radial direction. And the spokes 4 connecting the tread ring 2 and the hub 3 are provided. In this example, the case where the airless tire 1 is formed as a passenger car tire is shown.

The tread ring 2 is a portion corresponding to a tread portion in a pneumatic tire, and includes a tread rubber portion 2A and a reinforcing cord layer 2B embedded therein. As the tread rubber portion 2A, a rubber composition having excellent frictional force against grounding and abrasion resistance can be preferably adopted. Further, on the ground contact surface S which is the outer peripheral surface of the tread ring 2, tread grooves (not shown) are formed in various pattern shapes in order to impart wet performance.

In this example, the reinforcing cord layer 2B is formed from a belt layer 5 and a band layer 6 arranged on the outer or inner side in the radial direction thereof. However, it can also be formed by only the belt layer 5 or only the band layer 6. The belt layer 5 is formed of one or more belt plies 5A and 5B in which tire cords are arranged at an angle of, for example, 10 to 45 degrees with respect to the tire circumferential direction, in this example, two belt plies 5A and 5B. The rigidity of the tread ring 2 is increased by the tire cords intersecting each other between the plies. The band layer 6 is formed of one or more band plies in which the tire cord is spirally wound in the tire circumferential direction, in this example, one band ply.

As the tire cord of the belt layer 5 and the tire cord of the band layer 6, a steel cord and an organic fiber cord can be appropriately used, respectively. In the case of the organic fiber cord, high modulus fibers such as aramid, polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) having high strength and elastic modulus can be preferably adopted.

The hub 3 corresponds to a tire wheel, and in this example, a disk-shaped disc portion 3A fixed to the axle J and a cylindrical disc portion 3A integrally formed at the outer end portion in the radial direction of the disc portion 3A. It is equipped with a spoke mounting portion 3B. A hub hole 3A1 through which the front end portion Ja of the axle J is inserted is formed in the center of the disk portion 3A. Further, around the hub hole 3A1, a plurality of bolt insertion holes 3A2 for fixing the bolt portion Jb arranged on the axle side with a nut are provided. As with conventional tire wheels, such hubs 3 are preferably formed of, for example, a metal material such as steel, aluminum alloy, or magnesium alloy.

The spokes 4 are formed of a thermosetting resin, and as shown enlarged in FIG. 3, the spokes 4 integrally include an outer annular portion 4A, an inner annular portion 4B, and a spoke portion 4C. As the thermosetting resin, for example, epoxy-based resin, phenol-based resin, urethane-based resin, silicon-based resin, polyimide-based resin, melamine-based resin and the like can be used. In particular, urethane-based resin is preferably used because it has excellent elastic properties. sell.

The outer annular portion 4A is a cylindrical body concentric with the axle J, and the outer peripheral surface 4AS of the outer annular portion 4A is a first adhesive layer 21 made of an adhesive on the inner peripheral surface 2S of the tread ring 2. It is joined via. The inner annular portion 4B is a cylindrical body concentrically arranged inside the outer annular portion 4A in the radial direction, and the inner peripheral surface 4BS of the inner annular portion 4B has an adhesive on the outer peripheral surface 3S of the hub 3. It is joined via a second adhesive layer 22 made of. Further, the spoke portion 4C integrally connects the outer annular portion 4A and the inner annular portion 4B.

As shown in FIG. 1, the spoke portion 4C of this example is formed from the spoke plate rows 10R in the circumferential direction. The spoke plate row 10R is formed by arranging a plurality of fin-shaped spoke plates 10 connecting between the outer annular portion 4A and the inner annular portion 4B in the circumferential direction.

In particular, in this example, as the spoke plate row 10R, as shown in FIG. 4A, a case where spoke plates 10 having the same angle θ with respect to the tire axial direction and having the same inclination are arranged in parallel with each other is shown. However, as shown in FIG. 4B, the spoke plate rows 10R include a first spoke plate 10a that is inclined at an angle θ on one side with respect to the tire axial direction, and a first spoke plate 10a that is inclined at an angle θ on the other side. The spoke plates 10b of 2 may be arranged alternately in the circumferential direction. Further, as shown in FIG. 4C, a first spoke plate row 10Ra in which the first spoke plates 10a are arranged in parallel with each other and a second spoke plate 10b in which the second spoke plates 10b are arranged in parallel with each other. It can also be formed by two rows with a spoke plate row 10Rb. When the spoke plates 10 are inclined at an angle θ in this way, the contact time of one spoke plate 10 becomes long, so that the vibration performance of the tire can be improved. The angle θ is not particularly limited, but is preferably 30 to 60 degrees, for example. As shown in FIG. 4D, the spoke plate row 10R can be formed by the spoke plates 10 having an angle θ≈0 degrees that are not inclined with respect to the tire axial direction.

Further, as shown in FIGS. 5A to 5D, the spoke portions 4C may include spoke plates 12 in the circumferential direction that extend continuously in the circumferential direction. In FIGS. 5A and 5B, the spoke plates 12 in the circumferential direction extend linearly in the circumferential direction. Further, in FIGS. 5C and 5D, the spoke plates 12 in the circumferential direction extend in a zigzag manner in the circumferential direction. Further, as shown as represented by FIG. 5D, when the spoke portion 4C includes the spoke plate 12 in the circumferential direction, the side plate portion extending outward in the tire axial direction from the side surface of the spoke plate 12 in order to increase the rigidity. 12e can also be provided. In particular, when the spoke plates 12 in the circumferential direction have a zigzag shape, it is preferable to provide the side plate portion 12e at the corner portion of the zigzag.

Next, a method of manufacturing the airless tire 1 will be described. As conceptually shown in FIG. 6, this manufacturing method includes an adhesive coating step P1, a preheating step P2, a mounting step P3, and a casting molding step P4.

In the adhesive application step P1, the adhesive layer 21 is formed by applying an adhesive to the inner peripheral surface 2S of the tread ring 2 that has been vulcanized in advance. The tread ring 2 is formed on a cylindrical drum by various tread constituent members (for example, a sheet-like member for forming a belt layer 5, a sheet-like member for forming a band layer 6, and a sheet-like member for forming a tread rubber portion 2A. It is formed by vulcanizing and molding an unvulcanized raw tread ring formed by sequentially winding members and the like in the circumferential direction in a vulcanization mold.

As the adhesive, for example, a vulcanized adhesive typified by the trade name "Chemlock" manufactured by Rhodefar East Co., Ltd. and the trade name "Metallock" manufactured by Toyo Kagaku Kenkyusho Co., Ltd. is preferably used. It can be appropriately selected according to the material of the body.

The method of applying the adhesive is not particularly limited, and various means such as a brush, a roller, and a spray can be adopted, but it is desirable that the thickness is uniform. The thickness of the adhesive layer 21 after drying is preferably in the range of 5 to 100 μm, and if it is less than 5 μm, the effect of the adhesive is not sufficiently generated. If the thickness exceeds 100 μm, the strength of the adhesive itself becomes a problem, and the possibility that the adhesive itself is destroyed increases. From this point of view, the lower limit of the thickness is more preferably 7 μm or more, and the upper limit is more preferably 50 μm or less.

In the adhesive coating step P1 of this example, the adhesive layer 22 is also formed on the outer peripheral surface 3S of the hub 3 by applying the adhesive. In this example, the same adhesive as the adhesive layer 21 is used for the adhesive layer 22, but different types of adhesives can also be used. Further, it is preferable to roughen the inner peripheral surface 2S and the outer peripheral surface 3S prior to the application of the adhesive.

In the preheating step P2, the tread ring 2 coated with the adhesive layer is preheated. The preheating method is not particularly limited, and various means such as an oven and a contact heater can be adopted, but heating by an oven is preferable for more uniform heating. The preheating time is preferably 30 minutes or more.

The preheating temperature Tr (° C.) of the tread ring 2 in the preheating step P2 preferably has a relationship of the following formula (1) with the mold temperature T (° C.) of the casting mold 30.
T-10 ≤ Tr --- (1)

The preheating temperature Tr may be higher than the mold temperature T. However, when the thermosetting resin is a urethane resin, the upper limit of the preheating temperature Tr is preferably 150 ° C. or lower. If the temperature exceeds 150 ° C., the urethane resin deteriorates and the desired physical properties cannot be exhibited.

The formula (1) is preferably satisfied immediately before the tread ring 2 is mounted in the casting die 30. Immediately before means 5 minutes or less. The preheating temperature Tr (° C.) is the surface temperature of the inner peripheral surface 2S of the tread ring 2, and the mold temperature T (° C.) is the surface temperature of the casting mold 30. The preheating temperature Tr (° C.) and the mold temperature T (° C.) can be measured by various thermometers such as a contact type thermometer and a non-contact type thermometer.

In the mounting step P3, the tread ring 2 coated with the adhesive layer 22 and the hub 3 are mounted in the casting mold 30. As a result, a space 31 for forming the spokes 4 is formed in the casting die 30 and between the tread ring 2 and the hub 3.

In the casting molding step P4, the spoke 4, the tread ring 2, and the hub 3 are integrated by injecting and curing the raw material liquid of the thermosetting resin into the space portion 31. The casting mold 30 is provided with a well-known heating means (not shown) such as an electric heater, the mold temperature T is controlled to be constant, and the mold is thermally cured by the heat from the heating means. The sex resin is cured. Reference numeral 30A in the figure is an upper mold portion of the casting mold 30.

Here, when the thermosetting resin is thermally cured, the thermosetting resin and the adhesive are formed at the interface K1 between the first adhesive layer 21 and the spokes 4 and the interface K2 between the second adhesive layer 22 and the spokes 4. Adhesive reaction with and exerts a strong bonding force. However, when the temperature of the tread ring 2 is extremely lower than the mold temperature T of the casting mold 30, the temperature of the interface K1 between the first adhesive layer 21 and the spokes 4 is lowered by the tread ring 2. The adhesion reaction rate at the interface K1 becomes slower than the curing rate of the thermosetting resin, and as a result, the progress of the adhesion reaction is delayed at the interface K1 and the bonding force becomes insufficient.

Therefore, in the present invention, the tread ring 2 is heated to the preheating temperature Tr by the preheating step P2. This prevents a delay in the adhesion reaction rate at the interface K1 and improves the bonding force.

Since the hub 3 is formed of a metal material, its specific heat and thermal conductivity are very low as compared with the tread ring 2 mainly made of a rubber material. Therefore, even when the temperature of the hub 3 is extremely low, the temperature of the hub 3 rises quickly due to the heat from the casting mold 30 after mounting on the casting mold 30. Therefore, the delay in the adhesion reaction rate at the interface K2 is small. Therefore, in this example, the hub 3 is not preheated, but can be preheated as requested by the tread ring 2.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

Based on the manufacturing method of the present invention, an airless tire having the basic structure shown in FIGS. 1 and 2 (a tire corresponding to a tire size of 145 / 70R12) was prototyped based on the specifications shown in Table 1. In addition, the appearance and durability of each prototype tire were tested.

Each tire has substantially the same specifications except for the preheating temperature Tr of the tread ring in the preheating step and the thickness of the adhesive layer in the adhesive coating step.

The outer reinforcing cord layer and the inner reinforcing cord layer are as follows, and each tire has the same specifications.
<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)

Urethane-based resin was used for the spokes of each tire, and "Chemlock 218E" (trade name manufactured by Road Far East Corporation) was used as the adhesive for the tread ring surface.

In the preheating step, the tread ring was heated in an oven for *** hours, and the preheating temperature Tr immediately before mounting on the casting mold was measured. In Comparative Example 1, the tread ring was mounted in the casting mold without the preheating step, and the casting molding step was started 1 hour later.

(1) Appearance:
The sample tire was taken out from the casting mold, and the adhesion state at the joint between the tread ring and the spoke was visually evaluated in three stages.
○-There is no problem with adhesion at the joint, and it is at a level where it can run.
△ --Spokes at the joints have some peeling, but they are at a level where they can run.
×-The spokes at the joints are often peeled off and cannot run.

(2) Durability:
The tires whose appearances were evaluated as ◯ and Δ were run on the drum for 10,000 km under a load (3 kN) and a speed (60 km / h) using a drum tester. Then, the state of adhesion of the joint portion between the tread ring and the spoke after running was visually evaluated in three stages.
○-No peeling.
△ --There is some peeling, but it is running.
×-Peeling occurred during the test, making it difficult to continue the test.

As shown in the table, in the examples, it can be confirmed that the joint strength between the tread ring and the spokes is increased and the durability can be improved by performing the preheating step.

1 Airless tire 2 Tread ring 3 Hub 4 Spoke 21 Adhesive layer 30 Casting mold 31 Space P1 Adhesive application process P2 Preheating process P3 Mounting process P4 Casting process S Ground surface

Claims (4)

An airless tire having a cylindrical tread ring having a ground contact surface, a hub for fixing an axle arranged radially inside the tread ring, and spokes made of a thermosetting resin connecting the tread ring and the hub. It ’s a manufacturing method,
An adhesive application step of applying an adhesive to the inner peripheral surface of a vulcanized tread ring to form an adhesive layer,
The mounting process of mounting the tread ring coated with the adhesive layer and the hub in the casting mold, and
Casting molding that integrates the spokes, tread ring, and hub by injecting and curing the raw material liquid of the thermosetting resin into the casting mold and the space between the tread ring and the hub. Including the process
Prior to the mounting step, it has rows preheating step of preheating a tread ring, wherein the adhesive layer has been applied,
A method for manufacturing an airless tire, characterized in that the preheating temperature Tr (° C.) of the tread ring by the preheating step has a relationship of the following formula (1) with the mold temperature T (° C.) of the casting die.
T-10 ≤ Tr --- (1) The method for manufacturing an airless tire according to claim 1, wherein the thermosetting resin is a urethane resin. The method for manufacturing an airless tire according to claim 2, wherein the preheating temperature Tr (° C.) of the tread ring by the preheating step is 150 ° C. or lower. The method for manufacturing an airless tire according to any one of claims 1 to 3, wherein the thickness of the adhesive layer after drying is 5 to 100 μm.

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