JP5227392B2 - Pneumatic tire and method for manufacturing pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire in which a bead wire winding method is improved to improve the durability of a bead portion.

  In recent years, as shown in FIG. 4, a manufacturing method (core method) of a pneumatic tire 1 using a core 13 having an outer surface 14 that approximates the shape of the inner surface of a tire at the time of internal pressure filling is disclosed in Patent Document 1 below. Proposed. In this type of manufacturing method, the inner liner 9, the carcass ply 6 </ b> A, the bead wire 10 constituting the bead core 5, the belt layer 7, the tread rubber 2 </ b> G, the side wall rubber 3 </ b> G, and the like are sequentially attached to the outside of the core 13. The raw cover 1 a is formed, and the raw cover 1 a is usually vulcanized together with the core 13. This method has an advantage that the uniformity of the pneumatic tire is improved because the stretch acting on the carcass and the belt during vulcanization can be kept small.

JP 2006-160236 A

  By the way, in the above-described core method, both ends of the carcass ply 6A cannot be folded back. For this reason, the bead core 5 formed by the core method employs a structure in which the bead wire 10 is spirally wound from the inner side to the outer side in the tire radial direction and arranged on both sides of the carcass ply 6A to sandwich the carcass ply 6A. ing.

  In such a bead core 5, as shown in FIG. 5 (a), the end portion 10e of the bead wire 10 is the outermost portion in the tire radial direction of the bead core 5 that easily generates a large stress due to the tensile force of the carcass ply when the tire rolls. Arranged in the inner layer 5a. The pneumatic tire 1 having such a bead core has a problem that rubber is peeled off at the outer end due to the stress concentration generated at the end 10e of the bead wire 10 and grows easily to cause damage to the bead 4 or the like. It was.

  Further, in order to suppress the stress concentration at the end portion 10e of the bead wire as described above, as shown in FIG. 5B, the end portion 10e of the bead wire 10 is extended so that the bead core 5 has the outermost radial direction. It can also be arranged in the outer layer 5b. However, such a pneumatic tire 1 has a problem that the uniformity of the tire is deteriorated because the extended bead wire 10f intersects the already wound bead wire 10g.

  The present invention has been devised in view of the above problems, and in a core construction method using a core, a pneumatic tire in which the bead wire winding method is improved to improve the durability of the bead portion. The main purpose is to provide a manufacturing method.

  According to the first aspect of the present invention, a carcass formed of a carcass ply extending across a toroidal shape between a pair of bead portions, and an inner end portion of the carcass ply at an inner end in a tire radial direction inside and outside in the tire axial direction. A pneumatic tire including an inner core and a bead core composed of an outer core, wherein the inner core is formed by spirally winding a bead wire from the radially outer side to the inner side of the tire, and the outer core is The bead wire is formed by spirally winding the bead wire from the inner side to the outer side in the tire radial direction on the outer side in the tire axial direction of the carcass, and the bead core is composed of one bead wire continuous from the inner core to the outer core. This is a pneumatic tire.

  The invention according to claim 2 is arranged inside and outside in the tire axial direction of a carcass formed of a carcass ply extending across a toroidal shape between a pair of bead portions, and an inner end portion of the carcass ply on the inner side in the tire radial direction. A method of manufacturing a pneumatic tire including a bead core including an inner core and an outer core, wherein a bead wire covered with unvulcanized rubber is wound in a spiral shape from the outer side in the tire radial direction to the inner core. After the inner step, after the inner step, a carcass pasting step of pasting the inner end portion of the carcass ply on the outer side in the tire axial direction of the inner core, and after the carcass pasting step, on the innermost layer of the inner core An outer step of forming an outer core by winding a bead wire positioned spirally from the inner side to the outer side in the tire radial direction on the outer side in the tire axial direction of the carcass By having the said bead core, a manufacturing method of the pneumatic tire and forming a single bead wire continuous from the inner core to the outer core.

  The pneumatic tire according to the present invention includes a carcass made of a carcass ply extending across a toroidal shape between a pair of bead parts, and an inner side arranged inside and outside in the tire axial direction of an inner end of the carcass ply in the tire radial direction. And a bead core composed of an outer core. The inner core is formed by spirally winding a bead wire from the outer side in the tire radial direction to the inner side, and the outer core spirals from the inner side to the outer side in the tire radial direction of the carcass. The bead core is formed of one bead wire continuous from the inner core to the outer core.

Thus, in the pneumatic tire of the present invention (and the pneumatic tire obtained by the manufacturing method of the present invention), the end portion of the bead wire is disposed on the outermost side in the tire radial direction of the bead core. Therefore, since the big stress concentration to the edge part of this bead wire can be controlled, the durability of a bead part improves. Furthermore, the bead wires that form the inner core need not intersect with other bead wires that form the inner core. Similarly, the bead wires that form the outer core need not intersect the other bead wires that form the outer core. Therefore, the weight balance of the bead portion can be made uniform and the tire uniformity can be maintained well. Furthermore, when manufacturing one bead core , the bead wire is cut only once, so that the manufacturing time of the tire can be shortened.

1 is a right half sectional view of a pneumatic tire according to the present invention. (A) thru | or (c) is a side view of the bead part explaining an inner side process and a carcass sticking process. (A) thru | or (c) is a side view of the bead part explaining a carcass sticking process and an outer side process. It is the right half surface sectional drawing of the raw cover obtained by a core construction method, and a core. It is a side view of the bead part explaining the formation process of the conventional bead core.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the right half of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2. In addition, a passenger car is provided that includes an inner liner 9 made of rubber excellent in air impermeability disposed inside the carcass 6 and on the tire cavity surface M.

  The pneumatic tire 1 in FIG. 1 shows a normal state in which a normal rim (not shown) is assembled with a rim and filled with a normal internal pressure and is in an unloaded state.

  Here, the “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, For ETRTO, use “Measuring Rim”. In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure for JATMA and the table “TIRE LOAD LIMITS AT for TRA” Maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 kPa for tires for passenger cars.

  The carcass 6 is composed of at least one carcass ply 6A having a carcass cord extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. In the carcass ply 6A, carcass cords made of, for example, organic fibers are arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator C direction. The carcass ply 6 </ b> A of the present embodiment extends between the pair of bead portions 4, 4 in a toroidal shape, and inner end portions 6 e on the inner sides in the tire radial direction on both sides thereof are not folded back by the bead core 5. It ends with.

  The belt layer 7 is composed of at least two belt plies 7A and 7B, in the present embodiment, in the tire radial direction, and in the outer two. Each of the belt plies 7A and 7B has a highly elastic belt cord such as a steel cord inclined at an angle of 15 to 40 ° with respect to the tire equator C. The belt plies 7A and 7B are overlapped so that the belt cords cross each other.

  In this embodiment, the bead core 5 includes an inner core 11 disposed on the inner side in the tire axial direction of the inner end 6e on the inner side in the tire radial direction of the carcass ply 6A, and an outer side in the tire axial direction of the inner end 6e. And an outer core 12 disposed. The inner end portion 6e of the carcass ply 6A is a portion extending from the bead portion 4 including the inner end of the carcass ply 6A.

  In the pneumatic tire 1 of the present invention, as shown in FIGS. 2 and 3, the inner core 11 has a bead wire 10 made of steel, such as hard steel wire, which is covered with unvulcanized rubber at the time of manufacture. The outer core 12 is formed by spirally winding the bead wire 10 on the outer side in the tire axial direction of the carcass 6 from the inner side to the outer side in the tire radial direction. ing. Further, the bead core 5 of the pneumatic tire 1 of the present invention is formed by a single bead wire 10 continuous from the inner core 11 to the outer core 12.

  In such a pneumatic tire 1, the winding start end portion 10 a (shown in FIG. 2A) of the bead wire 10 is disposed on the tire radial direction outermost layer 11 a of the inner core 11, and the winding of the bead wire 10 is performed. The terminal portion 10b (shown in FIG. 3C) is disposed on the outermost layer 12a in the tire radial direction of the outer core 12. That is, both the winding end portions 10a and 10b of the bead wire 10 are not arranged on the innermost layers 11b and 12b in the tire radial direction of the bead core 5 that receives a large stress due to the tensile force of the carcass ply when the tire rolls. Therefore, in the pneumatic tire 1 of the present invention, stress concentration occurring at the winding ends 10a and 10b is suppressed, and the durability of the bead portion 4 is improved.

In the bead core 5 of the present embodiment, as is apparent from FIG. 2 , the bead wire 10 c forming the inner core 11 is overlapped and wound in the tire radial direction. Therefore, the inner core 11 of this embodiment does not unbalance the amount of bead wires disposed in the tire circumferential direction. The same applies to the outer core 12. Therefore, the pneumatic tire 1 of the present embodiment can maintain the tire uniformity well. Furthermore, in this onset bright, the bead core 5, to be formed by a single bead wire 10 of the consecutive steps of cutting the bead wire only once. Therefore, the manufacturing time of the pneumatic tire 1 of the present invention is shortened.

  As shown in FIG. 1, the bead portion 4 of the present embodiment includes a hard portion in a region in contact with a rim (not shown) on the inner side in the tire radial direction of the bead core 5 and on the outer side in the tire axial direction of the outer core 12. A chafer rubber 4g made of the above rubber is arranged. Further, inner and outer apexes 8i and 8o are provided so as to taper from the inner side in the tire axial direction of the inner core 11 and the outer side in the tire axial direction of the outer core 12 to the outer side in the tire radial direction. Such chafer rubber 4g and apex 8i, 8o are useful for increasing the bending rigidity of the bead portion 4 and improving the steering stability.

  The pneumatic tire 1 configured as described above is manufactured by vulcanizing a raw cover 1a as shown in FIG.

  Next, the manufacturing method of the pneumatic tire 1 of this invention is demonstrated. This manufacturing method includes an inner step of forming the inner core 11, a carcass attaching step of attaching the carcass ply 6 </ b> A, and an outer step of forming the outer core 12.

  The pneumatic tire 1 of this embodiment is manufactured using the core 13 as shown in FIG. 4, for example.

  The core 13 of the present embodiment includes, for example, a pair of a three-dimensional outer surface 14 that approximates the inner shape of a tire in a 5% internal pressure state, and a bead-side end portion of the outer surface 14 that protrudes outward in the tire axial direction. And a flange surface 15. The inner shape of the tire here is the inner shape of the tire 1 to be manufactured. The “5% internal pressure state” refers to a state in which the internal pressure is reduced from the normal state to an internal pressure of 5% of the normal internal pressure. The cross-sectional shape of the tire in the 5% internal pressure state approximates the cross-sectional shape of the tire in the vulcanization mold. However, the outer surface 14 of the core is not necessarily limited to such a shape. The core 13 is preferably made of a metal material or heat resistant resin that can withstand heat and pressure during vulcanization.

  The outer surface 14 of the core 13 includes a tread molding surface 14a that molds the lumen surface of the tread portion 2 of the tire 1, a pair of sidewall molding surfaces 14b that mold the lumen surface of the sidewall portion 3, and a bead. And a pair of bead molding surfaces 14 c for molding the tire lumen surface of the portion 4.

  In the present embodiment, first, on the outer surface 14 of the core 13, the base portion 4ga of the chafer rubber 4g, the inner liner 9, and the bead molding surface 14c of the base portion 4ga and the inner liner 9 on the outer side in the tire axial direction. The inner apex 8i is pasted.

  The base portion 4ga of the chafer rubber 4g has, for example, an L-shaped cross section, and is placed on the flange surface 15 of the core 13 and wound in a ring shape.

  Further, the inner liner 9 can be formed on a three-dimensional curved surface by winding an unvulcanized and ribbon-shaped rubber strip (not shown) around the outer surface 14 of the core 13 along the circumferential direction thereof. Can be formed. For example, the rubber strip preferably has a width W of about 5 to 35 mm and a thickness t of about 0.5 to 2.0 mm. In the present embodiment, the entire area of the outer surface 14 of the core 13 is covered with the inner liner 9 and the base portion 4ga.

  Further, the inner apex 8i is disposed on the outer side of the tire radius of the base portion 4ga placed on the flange surface 15 and on the inner side portion of the inner core 11 in the tire axial direction. Such an apex 8i prevents the bead wire 10c of the inner core 11 from damaging the inner liner 9.

  Next, in this embodiment, the inner side process which forms the inner core 11 in the tire axial direction outer side of the inner apex 8i is performed.

  As shown in FIG. 2A, the process includes a step of attaching a winding start end portion 10a of the bead wire 10 to a predetermined position outside the flange surface 15 in the tire radial direction. The outer peripheral surface of the bead wire 10 is previously coated with unvulcanized rubber. At this stage, since the inner apex 8i is also unvulcanized rubber, the bead wire 10 can be easily attached to the inner apex 8i.

  For example, by rotating the core 13 around the tire rotation axis, the bead wire 10 continuously supplied from a supply device for the bead wire 10 (not shown) is wound spirally inward in the tire radial direction. At this time, for example, it is desirable to wind the bead wire 10 while pressing it on the inner apex 8i by a bead wire pressing device such as a roller (not shown). In FIG. 2A, the bead wire 10 in the second round is locally bent inward in the tire radial direction near the winding start end portion 10a of the bead wire 10 to avoid a collision with the start end portion 10a. However, for example, the bead wire 10 may have a radius that smoothly changes to avoid collision.

  Next, as shown in FIG. 2B, the inner core 11 is formed by winding the bead wire 10 five times in this embodiment. At this time, it is desirable that the bead wire 10 after the winding end 10c1 of the inner core 11 is kept in a free state without being attached to any rubber member.

  Next, a carcass sticking step is performed in which the inner end portion 6e of the carcass ply 6A is stuck to the outer side of the inner core 11 in the tire axial direction. In this step, as shown in FIGS. 2 (c) and 3 (a), for example, a plurality of strip-like ply pieces 16 that are longer in the radial direction of the tire than the length in the circumferential direction of the tire, The three-dimensional carcass ply 6A is formed with high accuracy by being linked to the outer side of the core 11 in the tire axial direction and in the tire circumferential direction. The ply pieces 16 of this embodiment are attached in order from the vicinity of the winding end 10 c 1 of the inner core 11. Further, the inner end portions 6e in the tire radial direction of the adjacent ply pieces 16 are arranged to face each other. In such a carcass sticking step, for example, the ply piece 16 is stuck by rotating the core 13 in the tire circumferential direction.

  Next, after the carcass 6 is formed by attaching the ply piece 16 to the entire circumference of the tire, an outer step of forming the outer core 12 is performed. As shown in FIG. 3B, the bead wire 10 continues from the winding end 10c1 to the tire shaft from the side edges of the ply pieces 16 and 16 of the carcass 6 without being cut even after the inner step. After exiting the outer side in the direction, the outer core 12 is then formed by being spirally wound from the inner side to the outer side in the tire radial direction. In this outer process, it is desirable that the bead wire 10 is pressed and attached to the carcass 6 by a wire pressing device, for example, as in the inner process.

  Therefore, the bead core 5 thus molded has the winding start end 10a and the winding end end 10b disposed on the outermost layer 11a of the inner core 11 and the outermost layer 12a of the outer core 12, respectively.

Then, as shown in FIG. 4 , the sub-portion 4gb, the belt layer 7, the side wall rubber 3G, the tread rubber 2G, etc., which are connected to the outer apex 8o and the base portion 4ga of the clinch rubber 4g and form the outer surface of the bead, are attached. Attached. In this way, the raw cover 1 a is formed on the outer surface 14 of the core 13.

  As mentioned above, although the especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  In order to confirm the effect of the present invention, a tire having the bead core of the present invention using the core shown in FIG. 4 and a conventional tire having the bead core shown in FIGS. 5 (a) and 5 (b) are vulcanized. Pneumatic tires were then prototyped and tested for breaking water pressure and uniformity. The main common specifications are as follows.

Number of carcass plies: 1 Carcass cord material: Polyester Carcass cord angle: 88 ° (against tire equator)
Number of belt plies: 2 Belt cord material: Steel Belt cord angle: + 28 °, -28 ° (to tire equator)
Bead wire rubber hardness: 80 degrees Bead wire wire material: Steel Tire size: 195 / 65R15

<Destruction water pressure>
Each sample tire was assembled with a rim of 6.0 JJ × 15, filled with water from the valve into the tire lumen, and measured the breaking water pressure when the bead core broke five times, and the average value of the breaking water pressure was determined. . The results were evaluated using an index with Conventional Example 1 being 100. Larger numbers are better.

<Uniformity>
Using a tire uniformity tester, RFV was measured in accordance with JASO C607: 2000 “Automatic tire uniformity test method”.
The tire measurement conditions are as follows.
Tire rotation speed: 60rpm
Air pressure: 200kPa
Longitudinal load: 4.63kN
The result was an average value of five tires, and was evaluated by an index with the reciprocal number of Conventional Example 1 being 100. Larger numbers are better. The test results are shown in Table 1.

  As shown in Table 1, it can be understood that the tires of the examples are superior in breaking water pressure and uniformity as compared with the conventional examples.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 5 Bead core 4 Bead part 6 Carcass 6A Carcass ply 10 Bead wire 11 Inner core 12 Outer core

Claims (4)

A carcass composed of a carcass ply extending between a pair of bead portions in a toroidal shape, and a bead core composed of an inner core and an outer core disposed inside and outside in the tire axial direction of the inner end of the carcass ply in the tire radial direction A pneumatic tire including
The inner core is formed by spirally rolling a bead wire from the outside in the tire radial direction to the inside, and
The outer core is formed by spirally winding the bead wire from the inner side to the outer side in the tire radial direction on the outer side in the tire axial direction of the carcass,
The pneumatic tire according to claim 1, wherein the bead core includes a single bead wire continuous from the inner core to the outer core. A carcass composed of a carcass ply extending between a pair of bead portions in a toroidal shape, and a bead core composed of an inner core and an outer core disposed inside and outside in the tire axial direction of the inner end of the carcass ply in the tire radial direction A pneumatic tire manufacturing method including:
An inner step in which a bead wire covered with unvulcanized rubber on the bead portion is spirally wound from the outside in the tire radial direction to the inside to form an inner core;
After the inner step, a carcass sticking step of sticking the inner end portion of the carcass ply to the outer side in the tire axial direction of the inner core;
After the carcass pasting step, an outer step of forming an outer core by winding a bead wire located in the innermost layer of the inner core spirally from the inner side to the outer side in the tire radial direction on the outer side in the tire axial direction of the carcass. Thus, the method of manufacturing a pneumatic tire is characterized in that the bead core is formed of a single bead wire continuous from the inner core to the outer core. 2. The pneumatic tire according to claim 1, wherein the inner core and the outer core have the second round bead wire bent locally in the tire radial direction near a winding start end portion of the bead wire. 3. The method for manufacturing a pneumatic tire according to claim 2, wherein the inner core and the outer core are such that the bead wire in the second round is locally bent inward in the tire radial direction near a winding start end portion of the bead wire.

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