阅读说明：本技术 充气轮胎的制造方法 (Method for manufacturing pneumatic tire ) 是由 今誓志 河野好秀 于 2018-06-07 设计创作，主要内容包括：本发明的充气轮胎的制造方法是用于制造包括树脂包覆带束的充气轮胎的充气轮胎的制造方法,该树脂包覆带束由被包覆树脂包覆的线材构成,其中,所述充气轮胎在所述树脂包覆带束的轮胎径向内侧具备与所述树脂包覆带束的轮胎宽度方向外侧端接触的底环,所述制造方法包含底环形成工序,在该底环形成工序中,通过绕轮胎轴线卷绕带状构件来形成所述底环。(A method of manufacturing a pneumatic tire according to the present invention is a method of manufacturing a pneumatic tire including a resin-coated belt made of wire material coated with a coating resin, the pneumatic tire including a ground ring contacting with a tire width direction outer end of the resin-coated belt on a tire radial direction inner side of the resin-coated belt, the method including a ground ring forming step of forming the ground ring by winding a strip-like member around a tire axis.)

1. A method of manufacturing a pneumatic tire for manufacturing a pneumatic tire including a resin-coated belt composed of wire rods coated with a coating resin,

the pneumatic tire is provided with a bottom ring which is arranged on the inner side of the resin coating belt in the radial direction of the tire and is contacted with the outer end of the resin coating belt in the width direction of the tire,

the manufacturing method includes a bottom ring forming step of forming the bottom ring by winding a band-shaped member around a tire axis.

2. The manufacturing method of a pneumatic tire according to claim 1,

the bottom ring is made of resin.

Technical Field

The present invention relates to a method of manufacturing a pneumatic tire.

Background

Conventionally, in a pneumatic tire, in order to exert a hoop effect of fastening a carcass and improve rigidity of a tread, an operation of arranging a belt on an outer side of the carcass in a tire radial direction is generally performed (for example, patent document 1).

In recent years, in the process of increasing the demand for weight reduction of tires, a belt made of a wire material coated with a coating resin has been proposed. When such a resin-coated belt is used, the resin has higher rigidity than the weight, and therefore, the belt can function as a belt while reducing the weight.

Disclosure of Invention

Problems to be solved by the invention

However, when the resin-coated belt is used for the pneumatic tire, since the resin-coated belt has high rigidity, a rigidity step in which the rigidity in the tire circumferential direction changes abruptly in the tire width direction occurs with the tire width direction end of the resin-coated belt being defined as a boundary. Therefore, strain is likely to increase at the end of the resin-coated belt, and it is desirable to suppress occurrence of failure at the end of the resin-coated belt caused thereby. Further, although it is also considered to provide a member for relieving strain, it is troublesome to prepare a member having an appropriate shape for each tire type and tire size.

Accordingly, an object of the present invention is to provide a method of manufacturing a pneumatic tire, which can obtain a pneumatic tire in which failure at an end of a resin-coated belt is suppressed with high productivity.

Means for solving the problems

The main structure of the present invention is as follows.

The method for manufacturing a pneumatic tire of the present invention is a method for manufacturing a pneumatic tire including a resin-coated belt composed of wire rods coated with a coating resin,

the pneumatic tire is provided with a bottom ring which is arranged on the inner side of the resin coating belt in the radial direction of the tire and is contacted with the outer end of the resin coating belt in the width direction of the tire,

the manufacturing method includes a bottom ring forming step of forming the bottom ring by winding a band-shaped member around a tire axis.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method of manufacturing a pneumatic tire capable of obtaining a pneumatic tire in which failure at an end portion of a resin-coated belt is suppressed with high productivity.

Drawings

Fig. 1 is a schematic partial cross-sectional view in the tire width direction showing a half portion in the tire width direction of a pneumatic tire obtained by a method for manufacturing a pneumatic tire according to an embodiment of the present invention.

Fig. 2A is a schematic cross-sectional view of a bottom ring and a resin-coated belt obtained by the method for manufacturing a pneumatic tire according to the embodiment of the present invention.

Fig. 2B is a schematic side view of a bottom ring obtained by the method for manufacturing a pneumatic tire according to the embodiment of the present invention.

Fig. 3A is a schematic cross-sectional view of a bottom ring and a resin-coated belt obtained by the method for manufacturing a pneumatic tire of the comparative example.

Fig. 3B is a schematic side view of a bottom ring obtained by the method for manufacturing a pneumatic tire of the comparative example.

Detailed Description

Embodiments of the present invention are explained below in detail by way of examples with reference to the drawings.

Fig. 1 is a schematic partial cross-sectional view in the tire width direction showing a half portion in the tire width direction of a pneumatic tire obtained by a method for manufacturing a pneumatic tire according to an embodiment of the present invention. In fig. 1, only one half in the tire width direction with the tire equatorial plane CL as a boundary is shown, and the other half is not shown, but the other half has the same configuration. This pneumatic tire 1 (hereinafter also simply referred to as a tire) includes a resin-coated belt 4 composed of wire rods 4b coated with a coating resin 4a and a tread 5 in this order on the outer side in the tire radial direction of a crown portion of a carcass 3, and the carcass 3 is annularly laid over bead cores 2a embedded in a pair of bead portions 2.

The tire structure of the pneumatic tire obtained by the method for producing a pneumatic tire of the present invention is not particularly limited except for the point of including the above-described resin-coated belt 4 and the after-mentioned bottom ring 6, and a usual rubber structure can be conventionally used.

For example, although the example shown in fig. 1 includes the bead core 2a formed by binding steel wires, the material and shape of the bead core are not particularly limited, or a structure without the bead core 2a may be employed. In the present embodiment, the carcass 3 is formed of a single carcass ply made of organic fibers, but the material and number of the carcass plies are not particularly limited.

In the example shown in fig. 1, the resin-coated belt 4 is a spiral belt in which a resin-coated wire material in which a wire material 4b is coated with a coating resin 4a is spirally wound around the tire axis. Further, by providing the spiral belt, the resin-coated belt 4 can be formed by a simple method. Here, it is preferable that the resin-coated belt 4 is provided as one layer. This is because the resin containing the wire rods has high rigidity, and therefore, the rigidity of the tread can be sufficiently increased by one layer, and this is preferable from the viewpoint of weight reduction. The width of the resin-coated belt 4 in the tire width direction can be, for example, 90% to 120% of the tire contact width.

The wires 4b can be made of any known material, and for example, steel cords can be used. The steel cord can be, for example, a cord composed of a single filament or a multifilament of steel. In addition, organic fibers, carbon fibers, or the like can be used for the wires 4 b.

For example, a thermoplastic elastomer or a thermoplastic resin can be used as the coating resin 4a, and a resin crosslinked by heat or an electron beam or a resin cured by thermal rearrangement can be used. Examples of the thermoplastic elastomer include polyolefin thermoplastic elastomer (TPO), polystyrene thermoplastic elastomer (TPS), polyamide thermoplastic elastomer (TPA), polyurethane thermoplastic elastomer (TPU), polyester thermoplastic elastomer (TPC), and dynamic cross-linked thermoplastic elastomer (TPV). Examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a vinyl chloride resin, and a polyamide resin. The thermoplastic resin may be, for example, one having a deflection temperature under load (under a load of 0.45 MPa) of 78 ℃ or higher as defined in ISO 75-2 or ASTM D648, a tensile yield strength of 10MPa or higher as defined in JIS K7113, a tensile elongation at break (JIS K7113) of 50% or higher as defined in JIS K7113, and a vicat softening temperature (method a) of 130 ℃ or higher as defined in JIS K7206. The tensile modulus of elasticity (defined in JIS K7113: 1995) of the coating resin 4a of the coated wire rod 4b is preferably 50MPa or more. The tensile modulus of elasticity of the coating resin 4a coating the wire rod 4b is preferably 1000MPa or less. The coating resin 4a described here does not contain rubber (an organic polymer substance exhibiting rubber elasticity at normal temperature).

The spiral belt can be formed, for example, by: the resin-coated wire rod is formed by coating the outer peripheral side of the wire rod 4b with the coating resin 4a in a molten state and solidifying the coating resin by cooling, and the resin-coated wire rod is joined by welding the resin-coated wire rods adjacent in the axial direction of the annular body formed by winding the resin-coated wire rod while melting the coating resin 4a by hot plate welding or the like. Alternatively, the spiral belt may be formed by bonding resin-coated wires adjacent in the axial direction of the formed annular body with an adhesive or the like.

In the tire 1 shown in fig. 1, a bottom ring 6 that is in contact with (at least a part of) the tire width direction outer end 4c of the resin coated belt 4 is located at the same position in the tire width direction as the tire width direction outer end 4c of the resin coated belt 4 is provided on the tire radial direction inner side of the resin coated belt 4. In the example shown in fig. 1, the bottom ring 6 is an annular member (which extends continuously in the tire circumferential direction in this example) made of resin in this example. The resin may be the same as the coating resin 4a of the resin-coated belt 4, or may be a resin different from the coating resin 4a of the resin-coated belt 4. When the resin of the bottom ring 6 is different from the coating resin 4a of the resin-coated belt 4, the thermoplastic elastomer or the thermoplastic resin exemplified above can be used as the material of the coating resin 4 a.

As shown in fig. 1, in this example, the tire width direction inner end 6a of the bottom ring 6 is located inward in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4, and the tire width direction outer end 6b of the bottom ring 6 is located outward in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4. In the present invention, it is preferable that the width of the bottom ring 6 in the tire width direction is 7% or more of the width of the resin coated belt 4 in the tire width direction. This is because the resin-coated belt 4 (particularly, when the spiral belt is wound) can be easily arranged at the time of production by setting the ratio to 7% or more. It is also preferable that the tire width direction center position of the bottom ring 6 is set to the tire width direction outer end 4c of the resin coated belt 4 and the tire width direction position in the vicinity thereof. This is because the resin-coated belt 4 (particularly, when a spiral belt is wound) can be easily arranged during production, and the effect of reducing the difference in rigidity between the resin-coated belt 4 and the rubber can be more reliably exhibited by the bottom ring 6 described later. The thickness of the bottom ring 6 may be 0.5mm to 2mm, and the distances in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4 to the tire width direction inner end and outer end of the bottom ring 6 may be 0mm or more, respectively. The dimension in the present specification is measured in a state where the tire is mounted on the application rim and filled with a predetermined internal pressure to be in an unloaded state (where "tire contact width" is a tire width direction distance between the contact edges in a state where the tire is mounted on the application rim and filled with the predetermined internal pressure to be in the unloaded state when the tire is mounted on the application rim and filled with the predetermined internal pressure to be in a state where the outermost position in the tire width direction of the contact surface in the state where the maximum load is applied is set as the contact edge). In the present specification, the "application Rim" refers to an industrial standard effective in a region where a tire is produced and used, and refers to JATMA YEAR BOOK of JATMA (japan automobile tire association), STANDARDS MANUAL of ETRTO (european tire and Rim technology organization) in europe, and a standard Rim (measurring Rim in STANDARDS MANUAL of ETRTO, and design Rim in TRA YEAR BOOK) described in the united states or application sizes described in the future, such as the YEAR BOOK of TRA (tire and Rim association). The "rim" includes a dimension that will be included in the industry standard in the FUTURE, in addition to the current dimension, and examples of the "dimension described in the FUTURE" include a dimension described as "fuel DEVELOPMENTS" in STANDARDS MANUAL 2013 edition of ETRTO, and when the dimension that is not described in the industry standard is a rim having a width corresponding to the bead width of the tire. The "predetermined internal pressure" refers to an air pressure (maximum air pressure) corresponding to the tire maximum load capacity of the JATMA standard or the like in the tire of the application size. In the case of a size not described in the above-mentioned industrial standard, "predetermined internal pressure" refers to an air pressure (maximum air pressure) corresponding to a maximum load capacity predetermined for each vehicle on which the tire is mounted. The "maximum load" refers to a load corresponding to the tire maximum load capacity of the JATMA standard or the like among tires of an application size, or, in the case of a size not described in the industrial standard, a load corresponding to the maximum load capacity prescribed for each vehicle on which the tire is mounted.

Fig. 2A is a schematic cross-sectional view of a bottom ring and a resin-coated belt obtained by the method for manufacturing a pneumatic tire according to the embodiment of the present invention. Fig. 2B is a schematic side view of a bottom ring obtained by the method for manufacturing a pneumatic tire according to the embodiment of the present invention.

In the method of manufacturing a pneumatic tire according to the present embodiment, the band-shaped member 6c is wound around the tire axis to form the bottom ring 6 into a predetermined shape (bottom ring forming step).

In the example shown in fig. 2A, the cross section of the bottom ring 6 is substantially triangular, and more specifically, in the cross section, the belt-shaped members 6c are arranged in 4 rows in the tire width direction, and one, two, three, and four layers are stacked in the tire radial direction in order from the row on the outer side in the tire width direction. Such winding can be formed, for example, by winding the belt-shaped member 6c in the tire radial direction by an amount of four layers from the tire radial direction inner side of the tire width direction innermost side, then by an amount of three layers from the tire radial direction inner side of the 2 nd row from the tire width direction inner side, then by an amount of two layers from the tire radial direction inner side of the 3 rd row from the tire width direction inner side, and then by an amount of one layer from the tire width direction outermost tire radial direction inner side. On the other hand, in the present invention, the winding order of the band-like member 6c in the bottom ring forming step is not particularly limited.

Further, after the bottom ring 6 is formed, the resin coated belt 4 is formed by spirally winding the bottom ring 6 as a base, so that the resin coated belt 4 can be more easily formed.

As shown in fig. 2B, when the winding start end is E1 and the winding end is E2, the length (overlapping length L) of the band-shaped member 6c from the full circumferential position (point F3 among points F1 to F3 in this example) located closest to the winding end E2 to the winding end (point E2 in this example) is not particularly limited, but may be, for example, 1/100 to 2/3 of the full circumferential distance from point F2 to point F3. This is because the contact area between the resin materials of the adjacent belt-shaped members 6c can be increased by 1/100 or more in the entire circumferential distance, thereby improving, for example, the adhesive strength and the welding strength, while the weight of the bottom ring 6 can be reduced by 2/3 or less in the entire circumferential distance.

The following describes the operational effects of the method for manufacturing a pneumatic tire according to the present embodiment. Fig. 3A used for explanation is a schematic cross-sectional view of a bottom ring and a resin-coated belt obtained by the method for manufacturing a pneumatic tire of the comparative example. Fig. 3B is a schematic side view of a bottom ring obtained by the method for manufacturing a pneumatic tire of the comparative example.

In the example shown in fig. 3A, a bottom ring 6 having a triangular cross section is used according to a tire type and a tire size. In the example shown in fig. 3B, the bottom ring 6 is injection molded in a ring shape. However, there is a problem that productivity is low when a plurality of types of bottom rings 6 are prepared for each tire type and tire size.

In contrast, in the method of manufacturing a pneumatic tire according to the present embodiment, the bottom ring 6 having a substantially triangular cross section is formed by winding the (e.g., standardized) belt-like member 6c around the tire axis. Therefore, the shape and size of the bottom ring 6 can be formed in accordance with the tire type and the tire size each time by appropriately selecting, for example, the number of rows and/or the number of layers in the tire width direction of the belt-shaped member 6c, the size of the cross section of the belt-shaped member 6c, and the like, in accordance with the winding form of the belt-shaped member 6c (for example, standardized), and therefore, the productivity is higher than that in the case of preparing a plurality of types of bottom rings 6 molded in advance by injection molding, for example.

In the example shown in fig. 2A, the cross section of the bottom ring 6 is substantially triangular (specifically, as described above, the belt-shaped members 6c are arranged in 4 rows in the tire width direction in the cross section, and four layers, three layers, two layers, and one layer are formed in this order from the row at the innermost side in the tire width direction), and the cross section is similar to the shape of the bottom ring having a triangular cross section in the case of injection molding illustrated in fig. 3A. In this way, the shape and size of the bottom ring 6 can be adjusted to various shapes and sizes depending on the number of rows and layers of the strip-shaped member 6c to be wound, the size of the cross section of the strip-shaped member 6c, and the like.

In addition, in the present embodiment, since the bottom ring 6 is formed so as to be disposed on the inner side in the tire radial direction of the resin coated belt 4 so as to be in contact with the tire width direction outer end 4c of the resin coated belt 4, it is possible to alleviate the difference in rigidity between the resin coated belt 4 and the rubber.

As described above, according to the method for manufacturing a pneumatic tire of the present invention, a pneumatic tire in which failure at the end of the resin-coated belt 4 is suppressed can be obtained with high productivity.

In the present invention, it is preferable that the bottom ring 6 is made of resin. This is because the resin has higher rigidity than the weight, and therefore, the bottom ring 6, which is a member of the pneumatic tire, can be reduced in weight, and the effect of mitigating the difference in rigidity between the resin-coated belt 4 and the rubber can be further exhibited. In the present invention, when the bottom ring 6 is formed by winding the band-shaped members 6c, the workability in the bottom ring forming step can be improved by using a resin as a material and winding the band-shaped members 6c while joining the band-shaped members 6c to each other by welding (for example, hot plate welding or the like), adhesion, or the like. By using the resin as the material of the bottom ring 6 in this way, a pneumatic tire in which failure at the end of the resin-coated belt 4 is suppressed can be obtained with higher productivity, and further, it is advantageous to reduce the weight of the bottom ring 6.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments at all. For example, in the example shown in fig. 2A, the cross section of the bottom ring 6 is substantially triangular (specifically, as described above, the belt-shaped members 6c are arranged in 4 rows in the tire width direction in the cross section, and four layers, three layers, two layers, and one layer are formed in this order from the row at the innermost side in the tire width direction), but various shapes can be formed. The band-shaped members 6c may be provided as a bottom ring 6 having a substantially rectangular cross section, in which 3 rows are arranged in the tire width direction in the cross section and three layers are provided in all the rows. Alternatively, the bottom ring 6 may be formed such that the belt-like members 6c are arranged in 4 rows in the tire width direction in the cross section, and four, three, two, and one bottom ring 6 having a substantially triangular cross section are formed in this order from the outermost row in the tire width direction. The belt-like member 6c may be a member made of metal, organic fiber, or the like, in which a wire is put.

Description of the reference numerals

1. A pneumatic tire; 2. a bead portion; 2a, a bead core; 3. a carcass; 4. coating a belt with resin; 4a, coating resin; 4b, wire rods; 4c, resin-coated outer ends of the belt strips in the tire width direction; 5. a tread; 6. a bottom ring; 6a, the tire width direction inner end of the bottom ring; 6b, the tire width direction outer end of the bottom ring; 6c, a band-shaped member; CL, tire equatorial plane.