JP2004074647A - Method for manufacturing tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a rubber gauge thickness uniform by controlling the generation of creases on the inner peripheral face of a tread rubber. <P>SOLUTION: A band ply is formed by spirally winding a belt-like ply around the outer peripheral face of a profile deck and a belt-like tread rubber material is laminated on the outside of the band ply by passing the material around once to form a tread rubber. The tread rubber is formed with an approximately crescentic section by extruding it from a rubber extruder and the extruded tread rubber is laminated as it is on the band ply. The camber value of h2/L2 of the lower face of the tread rubber material during extrusion molding is 0.15 to 0.35. <P>COPYRIGHT: (C)2004,JPO

Description

【００３８】
実施例のタイヤは、皺の発生がほとんどなく、ゴムゲージ厚さのバラツキが非常に小さいため、タイヤのディフェクトの発生を招くことなく、操縦安定性及びユニフォミティーを向上しうるのが確認できる。なお比較例２では、５本中２本のタイヤに、トレッドゴムとバンドプライとの間に大きな空気溜まりが発生し、操縦安定性及びユニフォミティーをテストすることができなかった。
【００３９】
【発明の効果】
叙上の如く本発明は、所定のキャンバー値を有して押出し成形されたトレッドゴム材を、そのままプロファイルデッキに投入しているため、トレッドゴムの内周面における皺発生を抑制してゴムゲージ厚さを均一化でき、自動二輪車用タイヤにおいて操縦安定性及びユニフォミティーを向上させることができる。
【図面の簡単な説明】
【図１】本発明の製造方法により製造された自動二輪車用タイヤの一実施例を示す断面図である。
【図２】バンドプライに用いる帯状プライを示す斜視図である。
【図３】トレッドゴム材のゴム押出機からの押出し形状を説明する断面図である。
【図４】バンド形成工程及びトレッドゴム形成工程を概念的に説明する線図である。
【図５】本発明の製造方法を概念的に示す線図である。
【図６】搬送コンベヤ及び貼付けコンベヤにおけるトレッドゴム材の保持状態を示す断面図である。
【図７】自動二輪車用タイヤの略断面図である。
【図８】（Ａ）、（Ｂ）は、従来技術、及びその問題点を説明する線図である。
【符号の説明】
２Ｇ　　トレッドゴム
２Ｓ　　トレッド面
７Ａ　　バンドプライ
９　　　バンドコード
１０　　帯状プライ
２０　　プロファイルデッキ
３０　　ゴム押出機
Ｇ　　　トレッドゴム材
Ｇａ　　トレッド主部
Ｇｂ　　耳部
Ｓ１　　バンド形成工程
Ｓ２　　トレッドゴム形成工程
Ｔｃ　　タイヤ赤道点
Ｔｅ　　トレッド端[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention uses an extruded tread rubber material having a predetermined camber value to enable accurate sticking to a profile deck without causing wrinkles on an inner peripheral surface thereof, thereby improving tire steering stability and uniformity. The present invention relates to a method for manufacturing a motorcycle tire capable of improving the quality.
[0002]
[Prior art]
In the motorcycle tire, as shown in FIG. 7, the tread portion a is formed in a convex arc-shaped profile having a small radius of curvature due to the characteristic that the vehicle body turns largely while banking. Therefore, in order to form a tread portion a of this type of tire, conventionally, as shown in FIG. 8A, a profile deck b adapted to the convex arc profile is used, and a band is formed along the outer peripheral surface thereof. The ply c and the tread rubber d are sequentially laminated.
[0003]
At this time, in the band ply c, there is no particular problem because the narrow band-like ply c1 obtained by rubberizing the band cord is spirally wound along the outer peripheral surface of the profile deck b. However, in the case of the tread rubber d, a wide flat plate-shaped tread rubber material d1 is made to make a full circle to form a right cylindrical shape, and then the straight cylindrical body is moved from the tire equator side to the tread end using a well-known stitcher (not shown). It is rolled down inward in the radial direction while being pressed against the profile deck b toward the side.
[0004]
[Problems to be solved by the invention]
For this reason, as shown in FIG. 8B, wrinkles f occur on the inner peripheral surface of the tread rubber d due to the difference in circumferential length on the tread end side, causing unevenness of the rubber gauge thickness. This wrinkle f is remarkable in a tire in which the camber value h1 / L1 of the tread portion a exceeds 0.3, as shown in FIG. 7, for example, at a height p which is 10 mm radially inward from the tread end ae. , A variation of about 0.3 to 0.7 mm is generated in the thickness of the rubber gauge from the carcass. This reduces the steering stability and uniformity of the tire.
[0005]
Therefore, the present invention is based on the fact that a tread rubber material having a predetermined camber value and extruded and molded is directly charged into a profile deck, and wrinkles on the inner peripheral surface of the tread rubber are suppressed to reduce the thickness of the rubber gauge. An object of the present invention is to provide a method for manufacturing a motorcycle tire that can be made uniform and can improve steering stability and uniformity.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present application provides a tire axial width L1 and a radial height between a tire equator point on a tread surface and a tread end when a normal internal pressure is charged. A method for manufacturing a motorcycle tire having a convex arc-shaped tread profile in which a camber value h1 / L1, which is a ratio with respect to h1, is 0.3 to 0.7,
A band forming step of forming a band ply by spirally winding a long band-shaped ply rubberized on a band cord on an outer peripheral surface of a profile deck having a contour shape for forming the tread profile,
A tread rubber forming step of forming a tread rubber by laminating a band-shaped tread rubber material once around the outside of the band ply,
The tread rubber material has a substantially crescent-shaped cross-sectional shape having tapered ears extending diagonally outward and downward on both sides of the tread main portion, and is extruded from a rubber extruder. While being laminated on
When extruded from the rubber extruder, the lower surface of the tread rubber material has a camber value h2 / L2, which is the ratio of the width L2 to the height h2, from the center point in the width direction to the outer end point in the width direction. Is set to 0.15 to 0.35.
[0007]
In the invention of claim 2, the ratio h1 / H of the height h1 in the radial direction to the height H of the tire section is 0.35 to 0.65.
[0008]
In the invention according to claim 3, the tread rubber material is pressed by the band ply when the tread rubber material is attached to the band ply.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples. FIG. 1 is a meridional sectional view showing a normal internal pressure state of a motorcycle radial manufactured by the manufacturing method of the present invention.
Note that the normal internal pressure state is a state in which the tire mounted on the normal rim is filled with the normal internal pressure, and the `` normal rim '' is a standard system including a standard on which the tire is based. For example, JATMA means a standard rim, TRA means "Design Rim", or ETRTO means "Measuring Rim". The “regular internal pressure” is an air pressure defined for each tire according to the standard, and is a maximum air pressure for JATMA, and a maximum value described in a table “TIRE LOAD LIMITS AT VARIOUS COLD INFLASION PRESSURESRES” for TRA. In the case of ETRTO, it is "INFLATION PRESSURE".
[0010]
In FIG. 1, a motorcycle tire 1 (hereinafter, referred to as a tire 1) includes a carcass 6 extending from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3, a carcass 6 inside the tread portion 2 and the carcass 6. And a band layer 7 disposed outside the substrate.
[0011]
The carcass 6 is formed of at least one carcass ply 6A in which carcass cords are arranged at an angle of, for example, 70 to 90 degrees with respect to the tire circumferential direction, in this example, one carcass ply 6A. The carcass ply 6A has, at both ends of a ply body portion 6a extending between the bead cores 5, 5, a series of folded portions 6b which are folded back from inside to outside around the bead core 5 and are locked. A bead apex rubber 8 extending radially outward from the bead core 5 is provided between the main body portion 6a and the folded portion 6b.
[0012]
The band layer 7 includes at least one band ply 7A in which band cords 9 are arranged at an angle of 5 degrees or less with respect to the tire circumferential direction, and in this example, one band ply 7A. As shown in FIG. It is formed by spirally winding a long and narrow band ply 10 obtained by rubberizing the cord 9.
[0013]
A tread rubber 2G is laminated radially outside the band layer 7 to form the tread portion 2.
[0014]
Here, the tread portion 2 is a ratio between the width L1 in the tire axial direction and the height h1 in the radial direction between the tire equator point Tc on the tread surface 2S and the tread end Te in the normal internal pressure filling state. A convex arc-shaped tread profile having a small radius of curvature with a camber value h1 / L1 (hereinafter referred to as a tire camber value h1 / L1) of 0.3 to 0.7 is provided. The turning performance unique to motorcycles is secured. In particular, in this example, the ratio h1 / H of the radial height h1 to the tire section height H is set in the range of 0.35 to 0.65, and the ratio of the tread portion 2 to the tire section height H is increased. In this case, the turning performance is further enhanced, and the tire can be suitably implemented, for example, as a high-performance tire for racing or the like. The "tire cross-section height H" means a radial height from a tire axial line (bead base line) passing through the rim diameter position of the normal rim to the tire equator point Tc.
[0015]
Then, in the tire manufacturing method of the present invention, as shown in FIG. 3, a profile deck 20 having a contour shape 20S for forming the tread profile is used.
(1) a band forming step S1 of forming the band ply 7A by spirally winding the band-shaped ply 10 on the outer peripheral surface thereof;
{Circle around (2)} A tread rubber forming step S2 of forming a tread rubber 2G by laminating a belt-shaped tread rubber material G once around the outside thereof;
To form a tread ring for forming a tread.
[0016]
The profile deck 20 may be the same as the conventional profile deck, and its contour shape 20S is usually the deck width L3 between the width-direction center point 20c and the width-direction outer end point 20e of the contour shape 20S. The camber value h3 / L3 (hereinafter, referred to as the deck camber value h3 / L3), which is the ratio of the camber value h3 / L3 to the deck height h3, is formed in a single arc shape with 0.15 to 0.35. The deck camber value h3 / L3 is smaller than the tire camber value h1 / L1, and is generally set in the range of 0.6 to 0.95 times the tire camber value h1 / L1. .
[0017]
In the band forming step S1, the band ply 7A is formed by spirally winding the band-like ply 10 on the outer peripheral surface of the profile deck 20, as in the related art. At this time, since the band-like ply 10 is narrow, the band ply 7A can be formed along the profile deck 20 without having wrinkles over the entire width. For that purpose, it is preferable that the ply width W1 of the band-like ply 10 is 3 to 5 mm.
[0018]
In the tread rubber forming step S2, the tread rubber 2G is formed by laminating the wide band-shaped tread rubber material G around the outside of the band ply 7A once. The front and rear ends of the circuit are joined such that their end faces abut against each other.
[0019]
In the tread rubber forming step S2, what is different from the conventional one is that the tread rubber material G is extruded from a die 31 of a rubber extruder 30 with a predetermined camber value h2 / L2, and the extrusion is performed. The purpose is to supply the molded tread rubber material G to the profile deck 20 as it is.
[0020]
More specifically, as shown in FIG. 4, the tread rubber material G is formed from a base 31 of a rubber extruder 30 on both sides of a tread main portion Ga, and has an approximately crescent-shaped lug Gb extending diagonally outward and downward. It is extruded with a cross section of a shape. At this time, the tread rubber material G has a camber value h2 / L2 (hereinafter, referred to as a ratio between the width L2 and the height h2 on the lower surface gs between the width center point gc and the width direction outer end point ge). The rubber material camber value h2 / L2) is set in the range of 0.15 to 0.35.
[0021]
Conventionally, in a rubber extrusion line, a tread rubber material is extruded into a flat plate with its lower surface flat, and then subjected to a cooling step, and is cut to a length required for one tire. Thereafter, the rubber material of each fixed size is temporarily placed and stored on a tray as an intermediate member. Then, in the tread forming line, the fixed-size cut rubber material is taken out of the tray and supplied to the profile deck 20.
[0022]
On the other hand, in the present invention, as schematically shown in FIG. 5, the tread rubber material G extruded from the rubber extruder 30 is combined with a transport conveyor 32, a cutting tool 33, and a sticking conveyor 34 in this example. It is directly supplied to the profile deck 20 via the above.
[0023]
The transport conveyor 32 is a roller conveyor in this example, and receives the tread rubber material G from the rubber extruder 30 and transports the tread rubber material G at a predetermined transport speed to the downstream side. In the transport conveyor 32, it is necessary to maintain the cross-sectional shape of the tread rubber material G during the transport, and in this example, as shown in FIG. 6, a conveyor in which a pair of rollers 35B are pivotally supported on a support shaft 35A. Using a roller 35, the tread rubber material G is held between the rollers 35B, 35B so as to straddle the central portion of the tread rubber material G. Thereby, it can be conveyed to various tread rubber materials G having different cross-sectional shapes for each tire size while maintaining the cross-sectional shape, and versatility can be improved. In order to maintain the cross-sectional shape, it is preferable that the distance J between the rollers 35B, 35B is 0.3 to 0.7 times the width 2 × L2 of the tread rubber material G.
[0024]
Further, in this example, a storage section 36 is provided between the rubber extruder 30 and the conveyor 32 to temporarily store the tread rubber material G by bending it in a U-shape. As is well known, the reservoir 36 absorbs the difference between the movement (including speed and timing) of the tread rubber material G on the upstream side and the movement on the downstream side to achieve a smooth operation. If the flexure is too large, the cross-sectional shape of the tread rubber material G may be deformed. Therefore, the radius of curvature R of the upper surface of the tread rubber material G in the maximum flexure state (state where the storage amount is the maximum) is set to 150 mm or more. It is preferable to regulate.
[0025]
Further, the cutting tool 33 has a well-known configuration having a cutting blade 33A such as an ultrasonic cutter, for example, and determines a tread rubber material G which is connected to the attaching conveyor 34 from the transport conveyor 32 by a predetermined length required for one tire. Cut it into pieces. The transport conveyor 32 can measure the transport distance, and is controlled by control means for intermittently feeding the tread rubber material G at the predetermined length.
[0026]
Further, in the present example, the pasting conveyor 34 is formed of a roller conveyor similar to the transport conveyor 32, and the downstream end thereof comes close to the outer peripheral surface of the profile deck 20, so that the tread rubber material G cut to the fixed size is removed. It can be supplied to and adhered to the profile deck 20 from the downstream end. Note that the bonding conveyor 34 is also formed using the conveyor roller 35 in order to maintain the cross-sectional shape of the tread rubber material G.
[0027]
As described above, in the present invention, the tread rubber material G is extruded in advance into a substantially crescent-shaped cross section having a predetermined rubber material camber value h2 / L2, and is directly laminated on the band ply 7A. The length difference is reduced, and the generation of wrinkles on the lower surface gs of the tread rubber material G can be suppressed. As a result, the thickness of the rubber gauge on the edge side of the tread rubber 2G is made uniform, and steering stability and uniformity can be improved. In addition, generation of cracks due to wrinkles is suppressed, which can contribute to improvement in durability.
[0028]
Here, if the rubber material camber value h2 / L2 is less than 0.15, the effect of suppressing wrinkles is not exhibited, and if it exceeds 0.35, air traps between the band ply 7A and the tread rubber material G. Tends to occur and the tread peeling damage tends to occur.
[0029]
Further, in order to suppress wrinkles, the rubber material camber value h2 / L2 is more preferably set to a range of 0.6 to 0.9 times the deck camber value h3 / L3. Preferably, as shown in FIG. 3, the rubber camber value h2 / L2 is smaller than the deck camber value h3 / L3. In the case of (h2 / L2) <(h3 / L3), in order to firmly adhere the tread rubber material G to the band ply 7A, and in the case of (h2 / L2) ≧ (h3 / L3), In order to exhaust air between the tread rubber material G and the band ply 7A, it is necessary to press the tread rubber material G against the band ply 7A using a known stitcher or the like.
[0030]
As described above, particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.
[0031]
【Example】
A motorcycle tire (195 / 65R420) having the structure shown in FIG. 1 was prototyped in accordance with the manufacturing method of the present invention with the specifications shown in Table 1, and the test stability, uniformity, and defect of each test tire were tested. In addition, the occurrence of wrinkles and the variation of the thickness of the rubber gauge in the test tire were measured.
[0032]
(1) steering stability;
The test tires were mounted on a large motorcycle (1500 cc) under an internal pressure (190 kPa), and the steering stability when the vehicle was running on a racing course was indicated by an index with the conventional example being 100 by sensory evaluation of the driver. The test was performed on each of the five tires, and the average value is shown in Table 1. The smaller the value, the better the steering stability.
[0033]
(2) Uniformity;
Using a high-speed uniformity machine, the high-speed RFV (speed 140 km / h) of the test tires (5 each) was measured under the internal pressure (200 kPa) and the load (2.26 kN), and the average value of each was compared with the conventional example. It was indicated by an index of 100. The smaller the value, the better the uniformity.
[0034]
(3) Defect;
Visual inspection of each of the five tires, inspection of the occurrence of cracks on the outer surface of the tire due to wrinkles and variations in the thickness of the rubber gauge, distortion of the tire due to air trapping between the tread rubber and the band ply, etc. did.
[0035]
(4) occurrence of wrinkles;
The state where the tread ring was removed from the profile deck was visually observed, and the length of wrinkles and the number of wrinkles were measured.
[0036]
(5) Variation of rubber gauge thickness;
Each of the five tires is disassembled, and the variation of the rubber gauge thickness Δt1 (maximum thickness−minimum thickness) at the tread edge and the variation of the rubber gauge thickness at a height position 10 mm radially inward from the tread edge. The amount Δt2 was measured, and the average value of each is shown in Table 1.
[0037]
[Table 1]

[0038]
Since the tires of the examples have almost no wrinkles and very small variations in the thickness of the rubber gauge, it can be confirmed that the steering stability and uniformity can be improved without causing the tires to be defective. In Comparative Example 2, a large air pocket was generated between the tread rubber and the band ply in two of the five tires, and the steering stability and uniformity could not be tested.
[0039]
【The invention's effect】
As described above, according to the present invention, since the tread rubber material extruded with a predetermined camber value is directly charged into the profile deck, the generation of wrinkles on the inner peripheral surface of the tread rubber is suppressed and the thickness of the rubber gauge is reduced. Thus, the steering stability and uniformity of the motorcycle tire can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of a motorcycle tire manufactured by a manufacturing method of the present invention.
FIG. 2 is a perspective view showing a band-like ply used for the band ply.
FIG. 3 is a cross-sectional view illustrating an extruded shape of a tread rubber material from a rubber extruder.
FIG. 4 is a diagram conceptually illustrating a band forming step and a tread rubber forming step.
FIG. 5 is a diagram conceptually showing a manufacturing method of the present invention.
FIG. 6 is a cross-sectional view showing a holding state of a tread rubber material on a transport conveyor and a sticking conveyor.
FIG. 7 is a schematic sectional view of a motorcycle tire.
FIGS. 8A and 8B are diagrams illustrating a conventional technique and its problems.
[Explanation of symbols]
2G Tread rubber 2S Tread surface 7A Band ply 9 Band cord 10 Strip ply 20 Profile deck 30 Rubber extruder G Tread rubber material Ga Tread main part Gb Ear part S1 Band forming step S2 Tread rubber forming step Tc Tire equatorial point Te Tread end

Claims (3)

In the state where the normal internal pressure is charged, the camber value h1 / L1, which is the ratio of the width L1 in the tire axial direction and the height h1 in the radial direction, between the tire equator point on the tread surface and the tread edge, is set to 0.3 to 0.3. A method for manufacturing a motorcycle tire having a convex arc-shaped tread profile set to 0.7,
A band forming step of forming a band ply by spirally winding a long band-shaped ply rubberized on a band cord on an outer peripheral surface of a profile deck having a contour shape for forming the tread profile,
A tread rubber forming step of forming a tread rubber by laminating a band-shaped tread rubber material once around the outside of the band ply,
The tread rubber material has a substantially crescent-shaped cross-sectional shape having tapered ears extending diagonally outward and downward on both sides of the tread main portion, and is extruded from a rubber extruder. While being laminated on
When extruded from the rubber extruder, the lower surface of the tread rubber material has a camber value h2 / L2, which is the ratio of the width L2 to the height h2, from the center point in the width direction to the outer end point in the width direction. Of 0.15 to 0.35. The method for manufacturing a motorcycle tire according to claim 1, wherein a ratio h1 / H of the radial height h1 to a tire sectional height H is 0.35 to 0.65. The method for manufacturing a motorcycle tire according to claim 1, wherein the tread rubber material is pressed by the band ply when the tread rubber material is attached to the band ply.

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