JPH09207525A - Pneumatic type cushion tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic type cushion tire which prevents mold collapsing of a bead core and generating of separation. SOLUTION: A wire 1 coated with unvulcanized rubber is wound, this wire 1 is coated with a coating member 6 of plain weave fabric or the like, a bead core 10 is formed. This bead core 10 is buried along a peripheral direction in 8 base rubber layer inside a tire. The coating member 6 coated with rubber may be used. The bead core 10, after the wound wire 1 is coated further with a rubber layer 8 into a circular section, may be coated with the coating member 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic cushion tire having a bead core embedded therein which is used as a tire for industrial vehicles such as forklifts.

[0002]

2. Description of the Related Art Conventionally, industrial vehicle tires are used at a relatively low speed but under a heavy load, and are sometimes used on a rough road. In addition to requirements such as properties, it is required that the rim is firmly attached.

Therefore, the cut resistance on the ground contact side of the tire,
A tread rubber with excellent wear resistance is used, and a high hardness base rubber with a high compression elastic modulus is used inside the tread rubber to increase the fitting pressure with the rim. Further, in order to more securely fit the rim, as described in JP-A-60-163704, a bead core in which wires wound in a plurality of stages and a plurality of rows are bundled is embedded in the tire inner peripheral side. There is also known one in which the pneumatic cushion tire and the rim are firmly fitted to each other to prevent rim slip.

[0004]

However, in such a conventional one, when compressed by a mold and vulcanization molded,
The bead core loses its shape, an unbalanced load is applied to the wire during traveling, which lowers the durability of the base rubber and creates a space around the wire due to separation with the base rubber, creating a load during traveling. There is a problem that the base rubber may be cracked due to the stress concentration due to.

Further, when the pneumatic cushion tire is assembled to the rim, the side surface of the pneumatic cushion tire is pressed to be fitted on the rim, but a large load at that time causes separation around the wire. There is a problem that the base rubber may be cracked, or if a large load is applied under a high load such as during sharp cornering, separation is likely to occur.

An object of the present invention is to provide a pneumatic cushion tire in which the bead core is prevented from being deformed or separated.

[0007]

In order to achieve the above object, the present invention takes the following means to solve the problem. That is, a pneumatic cushion tire is characterized in that a bead core obtained by covering a wound wire with a covering member is embedded in the tire in a circumferential direction.

Further, the bead core may be one in which the rubber-coated wire is wound and coated with the coating member, or the bead core may be one in which the wire is coated with the rubber-coated coating member,
Further, the bead core may be one in which the wound wire is further covered with a rubber layer in a circular cross section and then covered with the covering member.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG.
Is a wire made of steel or the like, and in this embodiment, four wires 1 are lined up and simultaneously covered with an unvulcanized rubber 2. The wire 1 is wound to form an annular shape as shown in FIG. At that time, as shown in FIG. 1C, the wire 1 is closely wound in a plurality of rows and a plurality of stages. For example, 4 rows × 4
The winding is performed in 6 rows, 6 rows × 4 rows, 8 rows × 4 rows, and the like. After winding, the end of the wire 1 is stopped by the retaining ring 4 as shown in FIG. Note that the wire 1 is not limited to being wound in a plurality of rows and a plurality of stages, and can be similarly implemented even if one wire 1 is wound in a ring shape (1 row × 1 stage). .

Next, the wound wire 1 is covered with a covering member 6, and the covering member 6 is, for example, as shown in FIG.
As shown in (a), the entire wound wire 1 is formed into a tubular shape into which the wire 1 can be inserted,
As shown in (b), the bending wire 1 may be coated on the inside. When folded inward, the lap cost is a few mm
It is sufficient if it is 0, and even if it is 0, it can be carried out.

The covering member 6 may be formed by arranging a plurality of fiber cords in parallel, or may be a cloth such as plain weave or woven fabric. As the fiber, for example, various fibers such as vinylon, nylon, polyester, and acrylic can be used, and a nylon fiber having a heat shrinkage property that shrinks by the heat action during vulcanization and tightly binds the wire 1 is preferable. .

The covering member 6 may be covered with unvulcanized rubber. For example, a thin rubber film may be pressure-bonded to both surfaces or one surface of the covering member 6 by topping, or a cloth may be used by friction. The unvulcanized rubber may be rubbed into the cloth of the covering member 6 utilizing the speed difference of the rolls. At that time, it is preferable to remove the rubber in the space defined by the warp and the weft.

By covering the covering member 6 with rubber, the covering member 6 adheres to the wire 1 and becomes easy to cover when covering. Further, by removing the rubber in the space defined by the warp yarns and the weft yarns, the weight of the covering member 6 is reduced, and air is released from the space, so that extra air is not entrained and the adhesion is excellent. The covering member 6 is not limited to a tubular member, but may be a tape-shaped member as shown in FIG. 3, and in this case, it is wound around the wire 1 as shown in the drawing. This covering member 6 may also be covered with rubber.

Further, the covering member 6 is formed in a thin tubular shape, and the wire 1 is inserted into the covering member 6 so that the wire 1 is inserted.
Can be coated, and the cloth can be similarly worked even if there is no space between the fibers, and in that case, the cloth may or may not be rubber-coated.

The wound wire 1 in the state shown in FIG.
Further, as shown in FIG. 4, a rubber layer 8 made of unvulcanized rubber may be formed on the outer circumference of the wire 1 so as to have a circular cross-sectional shape. Then, the rubber layer 8 may be covered with the covering member 6. For the rubber layer 8, it is preferable to use a high hardness rubber which is excellent in tear resistance and flexibility.

In this embodiment, the wire 1, the unvulcanized rubber 2,
A bead core 10 is formed by the covering member 6, or by the wire 1, the unvulcanized rubber 2, the covering member 6, and the rubber layer 8. After the bead core 10 is formed, first, a forming drum 12 as shown in FIG. 5 is used to form a semi-finished product called a so-called green tire.

The forming drum 12 is provided with a plurality of support members 16 radially arranged on the core member 14 and supported so as to be slidable in the radial direction, and each support member 16 has an outer peripheral member 18.
Is attached. Each outer peripheral member 18 has an arc shape, and as shown in FIG. 5B, when the support member 16 is slid outward in the radial direction and expanded, each outer peripheral member 18 is arranged in a substantially cylindrical shape, When the member 16 is slid inward to be narrowed, the outer diameter of the member 16 is reduced.

In a state where the molding drum 12 is in a narrowed state as shown in FIG. 5 (a), an unvulcanized base rubber sheet 20 is wound around the outer periphery thereof as shown in FIG. 6 (a). Then, as shown in FIG. 6B, the bead core 10 described above is used.
Is covered on the wound base rubber sheet 20.

Then, as shown in FIG. 6C, the outer peripheral member 18 is expanded to bring the base rubber sheet 20 into contact with the inner peripheral side of the bead core 10. Then, the base rubber sheet 20 is further wound on the bead core 10 as shown in FIG. As a result, the bead core 10 is embedded along the tire circumferential direction.

The base rubber sheet 20 preferably has a compounding weight ratio of SBR and natural rubber of about 2: 8 to 7: 3.
S spring type (A type) hardness (JISK6301-197
5) is preferably 85 or more. Further, short fiber cords such as nylon and polyester may be mixed for reinforcement. The base rubber sheet 20 is wound to a height such that it is in the range of 20 to 60% of the sectional height of the pneumatic cushion tire to form a base rubber layer.

After winding the base rubber sheet 20,
A tread rubber sheet 22 is wound thereon as shown in FIG. 6 (e) to form a tread rubber layer. The tread rubber layer is JIS spring type (A type) hardness (JISK6
301-1975) is preferably about 65 to 75, and one having abrasion resistance and cut resistance may be used.

A cushion rubber sheet made of soft rubber may be wound between the base rubber sheet 20 and the tread rubber sheet 22 to form an intermediate layer. The intermediate layer may have an intermediate hardness between the base rubber layer and the tread rubber layer. Also, bead wire 1
There is a tendency that the more the 0 is on the inner peripheral side, the stronger the fitting with the rim and the better the idling resistance, and the case that the outer peripheral side is moderately, the tire lateral rigidity is improved. In consideration of the anti-slip property and various types of rigidity, the position may be a position where these are balanced, and the effect of the present invention can be recognized at any position. The same applies to the position of the bead core 10 in the tire axial direction.

Next, the outer peripheral member 18 of the molding drum 12 is squeezed, the molding drum 12 is removed as shown in FIG. 6F, and the semi-finished product 24 thus formed is inserted into a mold (not shown). It is vulcanized by a hot press to form a pneumatic cushion tire. In this embodiment,
Although the case where two bead cores 10 are used has been described as an example, three or more bead cores 10 may be used, and in a tire of a small size, even if only one bead core 10 is used, the same effect is obtained.
The tread radius of the finished tire is 100-80.
Generally, it is about 0 mm.

The pneumatic cushion tire of the present invention thus formed and a conventional tire are vulcanized at a vulcanization temperature of 130.
The results shown in Table 1 were obtained by comparing and forming under the same vulcanization conditions of ˜160 ° C. and 1 to 6 hours. Where ○ is wire 1
Indicates that the wire 1 was not separated, Δ indicates that the wire 1 was partly separated, and x indicates that the wire 1 was completely separated.

[0025]

[Table 1]

As described above, even if the bead core 10 receives the acting force of the flow due to the rubber flow during the compression vulcanization molding, the wires 1 are integrally covered by the covering member 6, so that the individual wires 1 are separated. Injuries are prevented. Further, as shown in FIG. 4, by making the cross-section circular, the acting force of the rubber flow is dispersed, and the wire 1 is more reliably prevented from separating.
Further, during vulcanization, the air around the bead core 10 can be prevented from moving between the fibers of the covering member 6 and being diffused to form a cavity around the bead core 10. By covering the covering member 6 with rubber, the compatibility with the base rubber layer is also improved.

On the other hand, as shown in FIG. 7, when a pneumatic cushion tire is attached to a three-piece wheel 32 having a rim 26, a side ring 28, and a lock ring 30, the side surface of the pneumatic cushion tire is used. A load P is applied to the rim 26 and a pneumatic cushion tire is mounted on the rim 26. When a large load P is applied, separation may occur between the bead core 10 and the base rubber.

Table 2 shows overload P (overload of 30 t or more).
Is a table in which the occurrence of separation is compared with the conventional product. The comparison was made with a 3 piece wheel 32 and a 4 piece wheel. Here, ◯ indicates that separation did not occur, Δ indicates that partial separation occurred, and x indicates that separation occurred at multiple locations. In addition, -indicates the case where the experiment is not performed.

[0029]

[Table 2]

When the tire is mounted on the wheel, even if an overload P is applied to the side surface of the tire, the load is distributed to each wire 1 by the covering member 6 of the bead core 10, and the bead core 10
Since the load is received as a whole, local concentration of acting force can be prevented and separation can be prevented. Also, when an overload is applied, the covering member 6 expands and contracts accordingly,
The wire 1 is prevented from falling apart, and is also deformed together with the base rubber layer to prevent the occurrence of separation.

Table 3 shows the results of the running test of the pneumatic cushion tire of this embodiment in comparison with the conventional product. The running test was carried out by using the test machine shown in FIG. 8, and the test machine used a pneumatic cushion tire mounted on the rotating drum 34 on the wheel under a load W.
It is something that is pressed while adding.

In this test, first, 1
After 0 minutes of preliminary running, the vehicle was operated with a load W twice the maximum load capacity specified by the Japan Automobile Tire Manufacturers Association (JATMA) for 2 hours, and then a 1-hour rest period was defined as 1 cycle. This is the result of cycle execution.
The rotation speed of the rotary drum 34 is set to correspond to 10 km / h. Here, ◯ indicates that separation did not occur, Δ indicates that separation occurred at one or two locations, and x indicates that separation occurred at several locations.

[0033]

[Table 3]

Even when an excessive load is applied to the pneumatic cushion tire, the load is distributed to each wire 1 by the covering member 6 of the bead core 10, and the bead core 10
Since the load is received as a whole, local concentration of acting force can be prevented and separation can be prevented. If the wire 1 is separated or if separation occurs, cracks are likely to occur, but the pneumatic cushion tire of the present example has improved durability, so when the tread rubber layer is worn out, It is possible to scrape the tread rubber layer and attach a new tread rubber to form a recycled tire, which improves recyclability.

On the other hand, even if a part of the side surface of the tire is peeled off due to some trouble and the bead core 10 is exposed, the covering member 6 prevents the wire 1 from jumping out. Further, even if a large load is applied and the wire 1 is separated, since the covering member 6 is completely bonded to the base rubber portion, the wire 1 only moves within the covering member 6 and serves as the bead core 10. be able to.

Table 4 compares the generation of cracks when a load is applied to the pneumatic cushion tire of the present invention and the conventional pneumatic cushion tire while artificially causing separation. .
When the tire was mounted on the wheel, an excess load of 60 t or more was applied to cause separation. Here, ∘ indicates that cracks did not occur, and x indicates that cracks grew due to separation.

[0037]

[Table 4]

In the pneumatic cushion tire of the present invention, separation occurs between the covering member 6 and the wire 1, and the covering member 6 prevents the growth of cracks from the separation. As described above, the present invention is not limited to such embodiments at all, and can be implemented in various modes without departing from the gist of the present invention.

[0039]

As described above in detail, the pneumatic cushion tire of the present invention can prevent the bead core from being deformed or separated due to the loosening of the wire during vulcanization, assembly or running. Has the effect. Further, by covering the covering member with rubber, the affinity is increased and the occurrence of separation can be further prevented. Further, by covering the wire with a rubber layer in a circular cross section, the acting force due to the rubber flow during vulcanization can be dispersed to more reliably prevent the wire from coming loose.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a wire used in a pneumatic cushion tire according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of covering with a covering member according to the present embodiment.

FIG. 3 is an explanatory view of covering with a covering member as another embodiment.

FIG. 4 is a cross-sectional view of a bead core in which a wire according to another embodiment has a circular cross section with a rubber layer.

FIG. 5 is an explanatory diagram of a forming drum of this embodiment.

FIG. 6 is a process drawing of forming a green tire of this embodiment.

FIG. 7 is a cross-sectional view in which the pneumatic cushion tire of this embodiment is mounted on a wheel.

FIG. 8 is an explanatory diagram of a tire testing machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tire 2 ... Unvulcanized rubber 6 ... Covering member 8 ... Rubber layer 10 ... Bead core 20 ... Base rubber sheet 22 ... Tread rubber sheet 32 ... Wheel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyoshi Ueno 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Inside Kasugai Works, Aichi Tire Industry Co., Ltd. (72) Kuniharu Kaga 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Aichi Tire Industry Co., Ltd.Kasugai Works (72) Inventor Hiroshi Tanemura 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Aichi Tire Co., Ltd. Kasugai Works (72) Inventor, Tetsunori Makino Otsubo, Kasugai-shi, Aichi 1108 Aichi Tire Industry Co., Ltd., Kasugai Works (72) Inventor, Jitoshi Miyase, Otsubatsu, Taraku-cho, Kasugai City, Aichi Prefecture 1108 Aichi Tire Industry Co., Ltd., Kasugai Works (72) Inventor, Yuji Torisaki, Kasugai City, Aichi Prefecture 1108 Otsubo, Aichi Tire Industry Co., Ltd. (72) Akito Hisato Kato 1108 Otsubo, Taraku-cho, Kasugai-shi, Aichi Aichi Tire Industry Co., Ltd. Kasugai Works

Claims (4)

[Claims] 1. A pneumatic cushion tire, wherein a bead core in which a wound wire is covered with a covering member is embedded in the tire in a circumferential direction. 2. The pneumatic cushion tire according to claim 1, wherein the bead core is formed by winding the rubber-coated wire and coating the wire with the coating member. 3. The pneumatic cushion tire according to claim 1 or 2, wherein the bead core is formed by coating the wire with the rubber-coated coating member. 4. The bead core is characterized in that the wound wire is further covered with a rubber layer in a circular cross section and then covered with the covering member.
The described pneumatic cushion tire.