JP2004009666A - Pneumatic radial tire for aircraft and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for aircrafts that has excellent cut resistance, pressure tightness, and separation resistance. <P>SOLUTION: This manufacturing method includes the formation of a green tire by laminating a BT band (belt-tread band) which is made by overlaying a belt, cushion rubber, a protection ply, and tread rubber in this order to the outer circumference of the crown of a green case that is formed so as to have substantially the same internal shape as that of a tire product, and the valcunization of the green tire. The protection ply is formed by winding a narrow strip of one or a plurality of cords coated with rubber on the cushion rubber in a spiral manner where the cord or cords form a waveform of a prescribed amplitude and wavelength approximately along the circumferential direction of the tire. The expansion ratio of the tire diameter in the vulcanization process is limited to 0.5% or lower with respect to the expansion ratio of the belt. <P>COPYRIGHT: (C)2004,JPO

Description

【００４１】
表１の評価結果から、実施例１及び２は、比較例１及び２に比べて、耐圧性能及び耐セパレーション性が優れており、また、耐カット性については、実施例及び比較例のいずれについても保護層のコード切断が生じず、良好であった。
【００４２】
【発明の効果】
この発明によれば、保護層のコードの波形形状を適正に形成することができることによって、耐カット性、耐圧性能及び耐セパレーション性に優れた航空機用空気入りラジアルタイヤの提供が可能になった。
【図面の簡単な説明】
【図１】この発明に従う代表的な航空機用空気入りラジアルタイヤの幅方向半断面図である。
【図２】図１のタイヤのクラウン部の構成を示す図である。
【図３】無端交差ベルトの形成方法を説明するための図である。
【図４】保護層を従来法によって製造したときの斜視図である。
【図５】従来タイヤのクラウン部の構成を示す図である。
【符号の説明】
１　航空機用空気入りラジアルタイヤ
２　ビード部
３　ビードコア
４　ビードフィラー
５　カーカス
６　クラウン部
７ａ，７ｂ，７ｃ，７ｄ　コード層
８　ベルト
９　トレッド部
１０　保護層
１１　クッションゴム
１２，１３　位置
１４　無端交差ベルト
１５　ジョイント部
Ｅ　タイヤ赤道面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic radial tire for aircraft used under high internal pressure and heavy load conditions and a method for manufacturing the same, and more particularly, to effectively prevent tire destruction due to injury from a tread tread surface. Of the protective layer.
[0002]
[Prior art]
Since aircraft tires are used under high internal pressure and heavy load conditions, the contact pressure acting on the tread tends to be high. In such a case, at the time of take-off and landing at a high speed or at the position where the take-off and landing starts at the airport terminal When the vehicle travels at a low speed during so-called taxing, when a stepped portion such as a pebble or a metal piece scattered on the road surface is stepped on, the protrusion is liable to be damaged by a cut or the like from the tread portion tread surface. If this damage reaches the belt, it will be difficult to use the tire repeatedly due to correction, or if the failure is overlooked and continued to be used, the tire life may be significantly reduced. In some cases, it is possible that an accident could occur.
[0003]
In aircraft tires, as means for improving cut resistance due to protrusions from the tread portion tread, belts and tread rubbers, such as the tire proposed in Japanese Patent No. 2690531 filed and filed by the present applicant, are used. Between them, it is useful to provide a protective layer in which the waveform cords are arranged substantially along the circumferential direction of the tire.
[0004]
That is, when the tire passes over the protrusion, the cord of the protective layer located on the portion of the tire riding on the protrusion is partially stretched, and a large tension acts on the cord to cut the cord. In the case of a waveform cord, the cord can be extended by changing the waveform even if the protrusion is stepped on, so that the tension acting on the cord can be reduced, resulting in improved cut resistance. Because.
[0005]
Further, although there is a difference in outer diameter between the center portion of the tire and both side portions in the width direction, since the diameters are the same in the ground contact surface, the cords of the protective layers located at both ends are greatly extended in the circumferential direction.
[0006]
If the amplitude of the waveform code of the protective layer is small and the length of the waveform code of the protective layer per circumferential length is short, the input in the direction in which the code expands should be absorbed by the change in the waveform of the waveform code. The cords of the protective layer are easily damaged by the protrusions, and separation between the cord and the rubber around the cords is also easily caused.
[0007]
On the other hand, if the amplitude of the waveform code is increased to increase the length of the protective layer cord per circumferential length too much, the effect of suppressing the tread from protruding due to centrifugal force during high-speed running is reduced. Then, the tread rubber is easily peeled off.
In addition, a part of the tension acting on the cord of the belt is also applied to the cord of the protective layer, so that the pressure resistance of the tire can be sufficiently exhibited. This is not preferable because the cord cannot bear the tension.
[0008]
Therefore, it is very important that the waveform code of the protective layer be formed with a waveform having a predetermined amplitude and wavelength, and that the amplitude and wavelength be uniform over the entire circumference of the tire.
[0009]
However, when the inventor studied the tire described in Japanese Patent No. 2690531 in more detail, the following findings were obtained.
[0010]
That is, in the conventional tire manufacturing method, the bladder is inflated from the inside of the tire under the condition that the diameter expansion rate of the tire at the time of vulcanization molding is in the range of about 3 to 10% in terms of the belt diameter expansion rate. The vulcanization molding was performed with the tire pressed against the vulcanization mold.
[0011]
For this reason, even if the waveform code of the protective layer is formed with an appropriate amplitude and wavelength in a green tire, the waveform code of the protective layer will be elongated in the product tire by the difference in diameter between these tires, and After that, since the rubber and the cord are not integrated, the waveform of the cord tends to have an uneven shape on the circumference, large tension may concentrate on a part of the cord, and the separation between the cord and the rubber may occur. Occasionally, the pressure resistance may deteriorate.
[0012]
Further, in the conventional manufacturing method, the protective layer is formed by bonding strips having the same width to the cushion rubber 11 as shown in FIGS.
[0013]
However, according to this forming method, since the joint portion 15 (the cut portion of the cord) exists continuously in the tire width direction, the joint portion 15 may be easily damaged from the joint portion 15 and may reduce durability. In addition, there is a possibility that the uniformity may be deteriorated or the tire may be vibrated, which is not preferable in terms of productivity.
[0014]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for manufacturing a pneumatic radial tire for an aircraft, in which the waveform code of the protective layer can be formed with a predetermined amplitude and wavelength, as compared with the tire described in Japanese Patent No. 2690531.
[0015]
Another object of the present invention is to provide an aircraft having excellent pressure resistance, cut resistance, and separation resistance by appropriately setting the amplitude and wavelength of a waveform code provided on a protective layer using the above-described manufacturing method. And pneumatic radial tires.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a pneumatic radial tire for an aircraft of the present invention includes a belt, a cushion rubber, a belt, a cushion rubber, on an outer periphery of a crown portion of a green case formed into an inner surface shape substantially equal to an inner surface shape of a product tire. In a method for manufacturing a pneumatic radial tire for an aircraft, the method includes a step of bonding a BT band formed by sequentially laminating a protective layer and a tread rubber to form a green tire, and a step of vulcanizing the green tire. The layer is formed by spirally winding a narrow strip having one or a plurality of cords covered with rubber on the cushion rubber so that the cords have a waveform of a predetermined amplitude and wavelength substantially along the circumferential direction of the tire. And the diameter expansion ratio of the tire at the time of vulcanization molding is controlled to 0.5% or less as a belt diameter expansion ratio. It is to.
[0017]
Further, in the above-mentioned manufacturing method, as a means for restricting the diameter expansion rate of the tire at the time of vulcanization molding to 0.5% or less in terms of the diameter expansion rate of the belt, for example, the inside of a green tire, a product tire, It is preferable to perform vulcanization molding in a state where a high-rigidity core having an outer surface shape substantially equal to the inner surface shape is inserted.
[0018]
Further, the pneumatic radial tire for an aircraft of the present invention is a tire manufactured by using the above-described manufacturing method, wherein a cord is formed of rubber at an outer peripheral side of a crown portion of a radial carcass extending in a toroidal shape between a pair of bead cores. A belt composed of at least two layers of coated cord layers, a cushion rubber, a protective layer in which the cords extend substantially in the circumferential direction of the tire in a waveform having a predetermined amplitude and wavelength, and a tread portion. The protective layer is provided with an aramid cord or a steel cord having a tensile strength of 14.7 GPa or more.
Here, the tensile strength (also referred to as strength) was determined at a test temperature of 30 ° C. with an autograph manufactured by Shimadzu Corporation in accordance with the provisions of JIS L 1017-1982.
[0019]
In addition, the waveform of the cord of the protective layer has an amplitude of 5 to 25 mm and a wavelength of 2 to 5 times the amplitude, and the thickness of the cushion rubber is 1.5 to 4.5 mm, and / or The belt is composed of at least two cord layers, and at least two of the cord layers are endless formed by extending cords in a zigzag manner between positions at both ends of the cord layers. Preferably, it is a cross belt.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a typical left half section in the width direction of a pneumatic radial tire for an aircraft according to the present invention, and FIG. 2 shows lamination of members from a carcass located at a crown portion of the tire to a tread portion. It shows the state.
[0021]
The tire 1 shown in FIG. 1 has cords that are substantially radially arranged (specifically, arranged at an angle of 70 to 90 ° with respect to the tire equatorial plane E) between bead cores 3 buried in a pair of bead portions 2. 1, four up plies 5a to 5d folded from inside to outside around the bead core 3 and the bead filler 4 in FIG. 1, and two down plies extending from the crown portion 6 to both bead portions 2. The plies 5e and 5f have a carcass 5 formed in a so-called up-down ply structure.
[0022]
In addition, the tire 1 includes at least two cord layers formed by rubber coating steel cords on the outer peripheral side of the crown portion 6 of the carcass 5, and in FIG. 1 and FIG. A belt 8 composed of a total of four code layers 7a to 7d including two cord layers 7c and 7d constituting a normal cross belt with cord ends 7a and 7b and cord ends at both width end positions; A tread portion 9 reinforced by the belt 8 is provided, and between the belt 8 and the tread portion 9 is provided a protective layer 10 in which cords 10a having a corrugated shape are arranged. A cushion rubber 11 having a function of suppressing the shear strain generated between these cords and protecting the belt 8 at the time of rectification is disposed between the protective rubber 10 and the protective layer 10.
[0023]
The tread portion 9 includes a plurality of circumferential grooves 12 extending in the circumferential direction of the tire, as shown in the general tire, and a plurality of transverse grooves extending in a direction transverse to the circumferential grooves (not shown). A tread groove such as a groove, a plurality of sipes, and the like are provided as appropriate according to the application.
[0024]
The main feature of the present invention resides in that the tire having the above-described configuration is manufactured by using a manufacturing method described below, whereby the corrugated cord 10a provided on the protective layer 10 has the same shape as the cord at the time of vulcanization molding. There is almost no change in the waveform, and the predetermined amplitude and wavelength set in the green tire can be maintained even when the tire becomes a product tire.As a result, the code is formed over the circumference with the waveform of the set amplitude and wavelength. They can be arranged uniformly.
[0025]
Note that the cord 10a of the protective layer 10 is preferably an aramid cord or a steel cord having a tensile strength of 14.7 GPa or more, from the viewpoint of ensuring belt cord breakage resistance.
[0026]
Further, the waveform of the cord 10a of the protective layer 10 preferably has an amplitude of 5 to 25 mm and a wavelength of 2 to 5 times the amplitude. If the amplitude is less than 5 mm, it is insufficient for the circumferential extension in the ground plane due to the wave shape, and if it exceeds 25 mm, the width of the strip is too wide and the belt is too densely formed in the belt forming process. Yes, if the wavelength is less than twice the amplitude, the waves will be too dense to shape and difficult to shape, and if it exceeds five times, the absorption of the circumferential extension will be insufficient. is there.
[0027]
Further, the thickness of the cushion rubber 11 is preferably 1.5 to 4.5 mm. If the thickness is less than 1.5 mm, the strain around the cord will be insufficiently absorbed. If the thickness is more than 4.5 mm, the rubber gauge becomes too thick to store heat, thereby causing an early failure. Because it becomes.
[0028]
In addition, the belt 8 is composed of at least two code layers. Of these code layers, at least two code layers, and in FIG. 1, the two code layers 7a and 7b are, as shown in FIG. It is preferable that the endless cross belt 14 is formed by extending the cord in a zigzag manner between the positions 12 and 13 which are both ends of the cord layers 7a and 7b in order to prevent the occurrence of separation due to the cord end. Note that FIG. 3 shows only a part of the method for forming the endless cross belt 14 in order to explain the method.
[0029]
Next, a method for manufacturing the tire will be described.
First, a BT band formed by sequentially laminating a belt, a cushion rubber, a protective layer, and a tread rubber is attached to the outer periphery of a crown portion of a green case formed into an inner surface shape substantially equal to the inner surface shape of a product tire. A tire is formed, and then the green tire is set in a vulcanizing mold, and then vulcanized to manufacture a pneumatic radial tire for an aircraft.
[0030]
In the case of forming a green tire, the protective layer is formed of a narrow strip having one or a plurality of cords covered with rubber, and the cords are formed on the cushion rubber so that the cords have a predetermined amplitude and wavelength substantially along the tire circumferential direction. It is formed by helical winding so that
[0031]
Further, the diameter expansion rate of the tire at the time of vulcanization molding is limited to 0.5% or less in terms of the belt diameter expansion rate, so that the inner surface shape of the green tire is substantially equal to the inner surface shape of the product tire, In a state where the cord of the protective layer formed of the green tire is provided in the form of a waveform having a predetermined amplitude and wavelength, the cord can be maintained after being vulcanized and formed into a product tire. When the diameter expansion ratio exceeds 0.5%, there is a high possibility that local expansion occurs in or between members of the raw tire, and the local expansion leads to local thinning of gauges and the like. Can cause a failure.
[0032]
As a means for limiting the diameter expansion rate of the tire at the time of vulcanization molding to 0.5% or less in terms of the diameter expansion rate of the belt, for example, the inside of the green tire is substantially the same as the inner shape of the product tire. It is preferable to perform vulcanization molding with a high-rigidity core having an equal outer surface shape, particularly a split-type non-deformed high-rigidity core inserted, but instead of a high-rigidity core, a bladder is used as in a normal vulcanization molding method. May be used.
[0033]
What has been described above is merely an example of the embodiment of the present invention, and various changes can be made within the scope of the claims.
[0034]
【Example】
Next, a prototype pneumatic radial tire for an aircraft according to the present invention was prototyped and its performance was evaluated, and will be described below.
Example The tire of Example is a pneumatic radial tire for aircraft having a tire width direction half section shown in FIG. 1 and a tire size of 46 × 17.0R20 30PR, and the protective layer is formed of a narrow strip. On the cushion rubber, the cord is formed by spirally winding so as to have a waveform having the amplitude and wavelength shown in Table 1 substantially along the circumferential direction of the tire. , And the belt diameter expansion rate was set to 0%. Table 1 shows the type, structure, tensile strength, amplitude and wavelength of the cord of the protective layer. The thickness of the cushion rubber was 2.5 mm. In addition, other tire structures were the same as general pneumatic radial tires for aircraft.
[0035]
For comparison, a protective layer was formed by bonding a protective layer using a strip having the same width as shown in FIGS. 4 and 5 and bonding both ends together, as shown in FIGS. A comparative tire (comparative example) in which the diameter expansion rate of the belt was 5% as the belt diameter expansion rate was also experimentally manufactured.
[0036]
(Performance evaluation)
Each of the test tires was evaluated for pressure resistance, cut resistance and separation resistance, and will be described below.
[0037]
The pressure resistance performance was evaluated by measuring the water pressure at the time of destruction by supplying water with a pump to pressurize the tire from the inside and measuring the pressure.
[0038]
The cut resistance and the separation resistance are determined by the number of repetition cycles (number of cycles: until the cord breaks or the separation occurs in the protective layer) on a drum having hemispherical projections mounted on the drum under the following conditions. The maximum was 200 cycles.), And both performances were evaluated from the measured values.
Tire load: 143.1 kN
Tire pressure: 1090 kPa
Test speed: 32km / h
Running distance: 5 km / 1 cycle Time required for one cycle: 60 minutes (running + stopping)
[0039]
Table 1 shows the evaluation results. In addition, the pressure resistance performance shown in Table 1 is indicated by an index ratio when Example 1 is set to 100, and the larger the numerical value, the better the pressure resistance performance. Also, the numerical values of the separation resistance in Table 1 indicate the number of cycles when separation occurs, except for Example 1.
[0040]
[Table 1]

[0041]
From the evaluation results shown in Table 1, Examples 1 and 2 are superior to Comparative Examples 1 and 2 in terms of pressure resistance and separation resistance, and cut resistance was determined for both Examples and Comparative Examples. Also, no breakage of the cord of the protective layer occurred, which was good.
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, since the corrugated shape of the code | cord of a protective layer can be formed appropriately, it became possible to provide the pneumatic radial tire for aircraft excellent in cut resistance, pressure resistance, and separation resistance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional half-sectional view of a typical pneumatic radial tire for an aircraft according to the present invention.
FIG. 2 is a diagram showing a configuration of a crown portion of the tire of FIG.
FIG. 3 is a diagram for explaining a method of forming an endless cross belt.
FIG. 4 is a perspective view when a protective layer is manufactured by a conventional method.
FIG. 5 is a diagram showing a configuration of a crown portion of a conventional tire.
[Explanation of symbols]
Reference Signs List 1 pneumatic radial tire for aircraft 2 bead portion 3 bead core 4 bead filler 5 carcass 6 crown portions 7a, 7b, 7c, 7d cord layer 8 belt 9 tread portion 10 protective layer 11 cushion rubber 12, 13 position 14 endless cross belt 15 joint Part E Tire equatorial plane

Claims (6)

A BT band formed by sequentially superimposing a belt, a cushion rubber, a protective layer, and a tread rubber on the outer periphery of a crown portion of a green case formed into an inner surface shape substantially equal to the inner surface shape of a product tire is bonded to form a green tire. Forming, and a method of manufacturing a pneumatic radial tire for aircraft including a step of vulcanizing and molding this green tire,
The protective layer is formed by spirally winding a narrow strip having one or more cords covered with rubber on a cushion rubber so that the cords have a waveform having a predetermined amplitude and wavelength substantially along the circumferential direction of the tire. A pneumatic radial tire for an aircraft, wherein the rate of expansion of the tire at the time of vulcanization molding is limited to 0.5% or less in terms of the rate of expansion of the belt. 2. The method for manufacturing a pneumatic radial tire for an aircraft according to claim 1, wherein the green tire is vulcanized and molded with a highly rigid core having an outer shape substantially equal to the inner shape of the product tire inserted therein. A tire manufactured by the manufacturing method according to claim 1, wherein at least two layers of a cord are rubber-coated on an outer peripheral side of a crown portion of a radial carcass extending in a toroidal shape between paired bead cores. A belt composed of a cord layer, a cushion rubber, a protective layer in which the cord extends substantially along the circumferential direction of the tire in a waveform having a predetermined amplitude and wavelength, and a tread portion, and the cord of the protective layer Is an aramid cord or a steel cord having a tensile strength of 14.7 GPa or more, which is a pneumatic radial tire for aircraft. The pneumatic radial tire for an aircraft according to claim 3, wherein the waveform shape of the cord of the protective layer has an amplitude of 5 to 25 mm and a wavelength of 2 to 5 times the amplitude. The pneumatic radial tire for an aircraft according to claim 3 or 4, wherein the cushion rubber has a thickness of 1.5 to 4.5 mm. The belt is composed of at least two cord layers, of which at least two cord layers are endless intersections formed by extending cords in a zigzag manner between positions at both ends of the cord layers. The pneumatic radial tire for an aircraft according to claim 3, which is a belt.

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