JP3735428B2 - Pneumatic tire manufacturing method - Google Patents

Description

表１から明らかなように、本発明タイヤは、金型費用の削減と加硫時間の短縮を図ることができ、更に、従来タイヤより優れたユニフォーミティーと高速耐久性を示すことができるのが判る。
【００２９】
【発明の効果】
上述したように本発明の空気入りタイヤの製造方法は、予めトレッドパターンを型付けしたプレキュアトレッドをタイヤケーシングとは別個に成形し、それを未加硫のタイヤケーシングと一体化してグリーンタイヤにして加硫成形するので、金型費用を削減し、かつ加硫時間を短縮して生産性を改善することができる。また、プレキュアトレッドは、ストリップ状に押出した未加硫ゴムを円筒体に複数回巻き付けて接合部のない無端環状にした積層ゴムからなるので、良好なユニフォーミティーが得られ、かつそれに伴って高い高速耐久性の確保が可能になる。
【図面の簡単な説明】
【図１】本発明の方法により製造された空気入りタイヤの一例を示すタイヤ子午線半断面図である。
【図２】（ａ），（ｂ），（ｃ）は、それぞれ本発明のタイヤ製造方法において、プレキュアトレッドを成形する工程を示す説明図である。
【図３】（ａ），（ｂ）は、それぞれ本発明のタイヤ製造方法において、プレキュアトレッドをタイヤケーシングに取り付ける工程を一部破断した断面で示す正面図である。
【図４】本発明のタイヤ製造方法において、プレキュアトレッドとタイヤケーシングとの間の接合面端部を被覆する工程を一部破断した断面で示す正面図である。
【図５】本発明のタイヤ製造方法において、グリーンタイヤを金型に入れて加硫する工程を示す要部断面図である。
【図６】インジェクション押出機とスクリュー押出機とを組み合わせてストリップ状の未加硫ゴムを押し出すようにした押出装置の一例を示し、（ａ）はインジェクション押出機に未加硫ゴムを供給する状態を示す説明図、（ｂ）はインジェクション押出機が押出位置に降下した状態を示す説明図である。
【符号の説明】
１ トレッドゴム ２ ビード部
３ サイドウォール部 ４ カーカス層
５ ビードコア ７ ベルト層
８ 主溝 １０ 接着ゴム層
１１ 円筒体 １１ａ 外周面
１２，１４，１７ インジェクション押出機
１３ 外型 １６ 接合面端部
１８ 被覆層 ２３ 当て板
Ｇ グリーンタイヤ Ｔb タイヤケーシング
Ｔc プレキュアトレッド[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a pneumatic tire, and more particularly, to a method for manufacturing a pneumatic tire capable of obtaining high tire uniformity and high-speed durability while reducing manufacturing costs.
[0002]
[Prior art]
In general, a pneumatic tire is manufactured by bonding each unvulcanized tire component member to form a green tire and placing it in a mold to vulcanize and mold the tire. In this vulcanization molding, the tread is molded with a groove-shaped tread pattern designed to exhibit the required performance for each type of tire. Examples of the tread pattern include a rib pattern suitable for wear resistance on good roads, a block pattern excellent in traction, a lag pattern suitable for bad roads, and a block pattern with sipes suitable for icy and snowy roads. be able to.
[0003]
However, preparing a large number of molds for each type of tread pattern having different required characteristics in this way increases the manufacturing cost of the molds and increases the manufacturing cost of the tire.
In addition, since the tire vulcanization time is determined by the thickest tire shoulder, the vulcanization is continued until the vulcanization of the shoulder is completed even though the other parts have already been vulcanized. There is a problem that it is necessary to continue, waste of energy is caused, and physical properties are deteriorated in a portion which is overvulcanized.
[0004]
In addition, in conventional tires, the tread is formed to wrap a belt-shaped rubber material of a certain length around the tire casing and join the two ends together. There is a problem that the uniformity of the tire is lowered, and the high-speed durability is lowered as the uniformity is lowered.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a method of manufacturing a pneumatic tire capable of obtaining a high degree of uniformity and high-speed durability while reducing manufacturing costs by reducing mold costs and vulcanization time. is there.
[0006]
[Means for Solving the Problems]
The present invention for achieving the above object is to form an unvulcanized tire casing in which a carcass layer is mounted between a pair of left and right bead portions and a belt layer is disposed on the outer periphery of the carcass layer. Separately, a strip-shaped unvulcanized rubber is wound around the cylindrical body a plurality of times to form an endless annular laminated rubber, and a tread pattern is molded from the laminated rubber to the outer periphery to form a vulcanized or semi-cured endless annular rubber. A precure tread is formed, the annular precure tread is fitted to the outer peripheral surface of the tire casing to form a green tire, and the green tire is vulcanized.
[0007]
In this way, the tread is prepared as a vulcanized or semi-cured precured tread with a tread pattern molded separately from the tire casing, and this is vulcanized and molded into a green tire integrated with an unvulcanized tire casing Therefore, the green tire vulcanization mold can be shared with the same tire vulcanization mold regardless of the type of tread pattern. It can be greatly reduced, and it is not necessary to secure a large place for the mold as in the prior art.
[0008]
In addition, the use of the precure tread can determine the vulcanization time of the tire at a portion other than the shoulder portion having the maximum thickness, for example, a bead portion, so that the vulcanization time can be shortened.
Also, since the tread is formed into an endless ring by winding strip-shaped unvulcanized rubber multiple times, there are no joints in the tire circumferential direction, improving tire uniformity, and accordingly improving high-speed durability. be able to.
[0009]
In the present invention, the precure tread is prepared in a vulcanized or semi-vulcanized state. The semi-vulcanized is a tread that is molded when it is vulcanized and molded integrally with at least an unvulcanized tire casing. It is vulcanized to such an extent that the pattern does not deform, and is vulcanized 80% or more of complete vulcanization.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a pneumatic tire manufactured by the method of the present invention, in which an endless annular tread Tc is joined to an outer peripheral surface of a tire casing Tb via an adhesive rubber layer 10.
[0011]
The endless annular tread Tc forms a tread pattern including a main groove 8 on the outer peripheral surface of the tread rubber 1.
On the other hand, the tire casing Tb is connected to the left and right bead portions 2, the left and right sidewall portions 3 are extended outward in the tire radial direction, and a carcass layer 4 having a reinforcing cord oriented in the radial direction is arranged on the inner side thereof. The both ends 4A are folded back from the inner side of the tire so that the bead filler 6 is sandwiched between the left and right beat cores 5, and the reinforcing cord is disposed on the outer peripheral side of the carcass layer 4 with respect to the tire circumferential direction. Two belt layers 7 that are inclined and arranged so as to cross each other are arranged. CL is a tire center line passing through the tire equatorial plane.
[0012]
According to the present invention, the pneumatic tire having the above-described configuration is manufactured by the following process.
First, an unvulcanized tire casing Tb and a vulcanized or semi-cured tread Tc are prepared separately. Of these, the vulcanized or semi-cured tread Tc is formed by the steps of FIGS. 2 (a), 2 (b) and 2 (c). That is, as shown in FIG. 2A, the strip-shaped unvulcanized rubber m is directly applied to the outer peripheral surface 11a from the discharge nozzle 12a of the injection extruder 12 while rotating the cylindrical body 11 about the axis X. Extrude and wrap around the cylindrical body 11 in layers.
[0013]
As a winding method, for example, the discharge nozzle 12a is reciprocally moved in parallel with the axis X while being wound in layers. Further, each time the number of layers is increased, the reciprocation interval of the discharge nozzles 12a is sequentially narrowed, and the strip-shaped unvulcanized rubber m is wound away from the outer peripheral surface 11a of the cylindrical body, as shown in FIG. Such an endless annular laminated rubber having a thick central portion is formed.
[0014]
Alternatively, the strip-shaped unmodified rubber m is wound from one side of the cylindrical body 11 from the discharge nozzle 12a to increase the number of laminations and move to the opposite side, whereby the central portion of FIG. Form rubber.
Next, as shown in FIG. 2 (c), by covering the laminated rubber of the cylindrical body 11 with a split-type outer mold 13 having a groove forming blade 13a on the inner surface, this is heated and vulcanized and molded. An endless annular precure tread Tc formed with a tread pattern is formed. Here, the vulcanization of the tread may be in a semi-vulcanized state. Moreover, since the said cylindrical body 11 is used also for an internal type | mold, it is comprised with the metal body.
[0015]
On the other hand, the unvulcanized tire casing Tb is formed in the same manner as the green tire forming step in the known tire manufacturing method.
For example, a carcass layer in which unvulcanized rubber is rubberized is wound on a molding drum, bead cores are set on both ends thereof, the both end portions are folded back, and unvulcanized rubber on a sidewall portion is further attached. Next, after expanding the central portion in the width direction into an annular shape having a horseshoe cross section, an unvulcanized tire casing can be obtained by providing an unvulcanized belt layer on the outer periphery of the carcass layer.
[0016]
The precure tread and the tire casing prepared as described above are integrally joined and formed into a green tire.
In forming a green tire, since the tire casing is unvulcanized, it is not always necessary to provide the adhesive rubber layer 10 on the joint surface. However, in order to firmly bond the precure tread Tc, it is necessary to provide it. preferable.
[0017]
As a method of providing the adhesive rubber layer 10, an unvulcanized rubber sheet is generally attached, but preferably an injection extruder as illustrated in FIG. 3 is used.
That is, as shown in FIG. 3 (a), the strip-shaped unvulcanized rubber n is continuously extruded from the discharge nozzle 14a of the injection extruder 14 and wound a plurality of times so that the width of the precure tread Tc is satisfied. Then, the adhesive rubber layer 10 is formed by winding in an annular shape without any gap.
[0018]
Next, as shown in FIG. 3B, the green tire G is formed by fitting the precure tread Tc on the outer periphery of the rubber layer 10. When the adhesive rubber layer 10 is formed by pasting an unvulcanized rubber sheet, it is difficult to follow the curved surface of the tire casing outer periphery, so that wrinkles are generated and air is caught between the wrinkles, resulting in poor adhesion and uniformity. However, according to the strip winding, it is possible to greatly suppress these defects.
[0019]
The precure tread Tc may be buffed or coated with cement on the inner peripheral surface, which is an adhesive surface, as necessary.
The green tire G molded as described above can easily form a step at the joint surface end 16 between the unvulcanized tire casing Tb and the vulcanized or semi-cured precure tread Tc. . For this reason, preferably, as shown in FIG. 4, while rotating the green tire G, the strip-shaped unvulcanized rubber k is wound around the joint surface end portion 16 from the discharge nozzle 17a of the injection extruder 17 at least once. By forming the coating layer 18, the appearance can be improved.
[0020]
The green tire G formed as described above is set in a mold 20 as shown in FIG. 5 and vulcanized. During vulcanization, the precure tread Tc is firmly bonded to the outer peripheral side of the tire casing Tb through the adhesive rubber layer 10 to obtain the pneumatic tire shown in FIG.
The mold 20 is composed of upper and lower molds 21 for molding the sidewall part 3, upper and lower bead rings 22 for molding the bead part 2, and a contact plate 23 for pressing the tread surface of the precure tread Tc. 23 is fixed by a bolt 24. The groove forming blade is not provided at all on the inner peripheral surface of the contact plate 23, and has a curved surface along the tread surface. Therefore, it can be commonly used for vulcanization molding of any green tire regardless of the tread pattern.
[0021]
As described above, in the present invention, the pre-cured tread Tc previously molded with the tread pattern is formed separately from the tire casing, and this is integrated with the unvulcanized tire casing to form a green tire. There is no need to mold the tread pattern during vulcanization of G. Therefore, as shown in FIG. 5, as a mold for vulcanization molding of a green tire, it is only necessary to arrange a contact plate 23 that acts as an internal pressure pressing plate for the tread. Therefore, it becomes possible to share a vulcanization mold for a plurality of types of tires regardless of the tread pattern, thereby significantly reducing the mold cost. In addition, there is no need for a wide space as in the prior art in the mold place.
[0022]
Further, by using a precured tread Tc that has been pre-cured and molded, the vulcanization time of the tire can be determined at a portion other than the shoulder portion having the maximum thickness, for example, a bead portion. Can be shortened and productivity can be increased. Moreover, the physical property fall by overvulcanization can also be suppressed.
Further, the precured tread Tc is formed into a seamless annular shape from a laminated rubber obtained by winding a strip-like unvulcanized rubber m around the outer peripheral surface 11a of the cylindrical body 11 by an injection extruder 12, so that a good uniformity can be obtained. Moreover, high high-speed durability can be obtained by improving the uniformity.
[0023]
In the present invention, an example of manufacturing a pneumatic tire in which two layers of the belt layer 7 are provided on the tire outer peripheral side of the carcass layer 4 is shown in the above embodiment, but the present invention is not limited thereto, and other than the precure tread Tc. It goes without saying that the structure of the tire casing constituting this part can be changed as appropriate.
Further, the belt layer 7 may not be provided on the tire casing Tb side, but may be provided on the precure tread _Tc side.
[0024]
In the above embodiment, the strip-shaped unvulcanized rubber m, n, and k are directly extruded to the coated side by the injection extruders 12, 14, and 17, but indirectly through a guide member such as a roller. You may make it apply by extrusion.
In the present invention, a screw extruder that continuously extrudes may be used in place of the above-described injection extruder for constant volume extrusion. In that case, the required amount of rubber extrusion can be controlled by measuring the weight.
[0025]
Moreover, as shown in FIG. 6, it is also possible to perform extrusion molding by combining the injection extruder A and the screw extruder B. As shown in FIG. 6A, when a predetermined amount of unvulcanized rubber is supplied from the screw extruder B to the injection extruder A, the screw extruder B moves backward as shown in FIG. 6B, and the injection extruder A Is lowered to the extrusion position, and unvulcanized rubber is pushed out from the discharge nozzle C at the lower end.
[0026]
【Example】
An unvulcanized tire casing in which a pre-cured tread that is vulcanized and molded so as to pre-mold a tread pattern from strip-wrapped laminated rubber as described above is made common to tire sizes of 195 / 70R14 91H. The tire of the present invention, which is formed by vulcanizing a green tire integrated with a rubber tire, and a vulcanized molding of a green tire in which a tread is formed by wrapping an unvulcanized belt-like rubber around an unvulcanized tire casing according to a conventional method and splicing both ends. Each of the conventional tires was manufactured.
[0027]
When both of these test tires were mounted on a rim having a rim size of 14 × 51 / 2JJ, and an evaluation test for uniformity and high-speed durability was performed under the following measurement conditions, the results shown in Table 1 were obtained. Further, when the vulcanization time and mold cost of both test tires were determined, the results shown in Table 1 were obtained.
In addition, the vulcanization time of the tire of the present invention is indicated by an index value where the vulcanization time of the conventional tire is 100. The smaller the value, the shorter the vulcanization time.
The test was carried out in conformity with Uniformity JASO C607 “Automotive Tire Uniformity Test Method”, and the result was evaluated by an index value with the conventional tire as 100. The larger the value, the better the uniformity.
After completion of JIS D-4230, JIS high-speed durability test with a high-speed durability drum diameter of 1707 mm, the running time until breaking by adding 10 km / hr every 30 minutes was measured. The index value was evaluated. The higher the value, the better the high speed durability.
The mold cost required for producing 1000 die costs per day was calculated, and the result was evaluated by an index value with the cost required for producing the conventional tire as 100. The smaller the value, the lower the mold cost and the lower the cost. In the present invention, the cost of the mold for molding the precure tread is included, but the cost of the extruder is excluded.
[0028]
[Table 1]

As is apparent from Table 1, the tire of the present invention can reduce the mold cost and the vulcanization time, and can exhibit a uniformity and high-speed durability superior to those of conventional tires. I understand.
[0029]
【The invention's effect】
As described above, the method for manufacturing a pneumatic tire according to the present invention includes forming a pre-cured tread with a pre-molded tread pattern separately from the tire casing, and integrating the uncured tire casing into a green tire. Since vulcanization molding is performed, it is possible to improve the productivity by reducing the mold cost and shortening the vulcanization time. Precured tread is made of laminated rubber made of unvulcanized rubber extruded in a strip shape and wrapped around a cylindrical body multiple times to form an endless ring without joints. High speed durability can be secured.
[Brief description of the drawings]
FIG. 1 is a half sectional view of a tire meridian showing one example of a pneumatic tire manufactured by the method of the present invention.
FIGS. 2 (a), (b), and (c) are explanatory views showing steps of forming a precure tread in the tire manufacturing method of the present invention.
FIGS. 3 (a) and 3 (b) are front views each showing a partially broken cross section of a step of attaching a precure tread to a tire casing in the tire manufacturing method of the present invention.
FIG. 4 is a front view showing, in a partially broken cross section, a step of covering a joint surface end portion between a precure tread and a tire casing in the tire manufacturing method of the present invention.
FIG. 5 is a cross-sectional view of a principal part showing a step of vulcanizing a green tire in a mold in the tire manufacturing method of the present invention.
FIG. 6 shows an example of an extrusion apparatus that extrudes strip-shaped unvulcanized rubber by combining an injection extruder and a screw extruder, and (a) shows a state in which unvulcanized rubber is supplied to the injection extruder. (B) is explanatory drawing which shows the state which the injection extruder fell to the extrusion position.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread rubber 2 Bead part 3 Side wall part 4 Carcass layer 5 Bead core 7 Belt layer 8 Main groove 10 Adhesive rubber layer 11 Cylindrical body 11a Outer peripheral surface 12, 14, 17 Injection extruder 13 Outer mold | type 16 Joint surface edge part 18 Covering layer 23 Batch plate G Green tire Tb Tire casing Tc Precure tread

Claims (3)

A carcass layer is mounted between a pair of left and right bead portions, and an unvulcanized tire casing is formed in which a belt layer is disposed on the outer periphery of the carcass layer. On the other hand, a strip shape is formed around a cylindrical body separately from the tire casing. The unvulcanized rubber is wound a plurality of times to form an endless annular laminated rubber, and a vulcanized or semi-cured endless annular precured tread with a tread pattern formed on the outer periphery is molded from the laminated rubber. A pneumatic tire manufacturing method in which a green tire is formed by fitting the precure tread to the outer peripheral surface of the tire casing, and the green tire is vulcanized. 2. The air according to claim 1, wherein before the endless annular precure tread is fitted to the outer circumferential surface of the tire casing, a strip-shaped unvulcanized rubber is wound around the outer circumferential surface of the tire casing to form an adhesive rubber layer. A method for manufacturing a tire. At least one round of unvulcanized rubber in the form of a strip is wound along the edge of the joint surface between the tire casing and the precure tread to form a coating layer, and at least the mold is in contact with the coating layer The method for producing a pneumatic tire according to claim 1 or 2, wherein the green tire is vulcanized.

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