JP5404240B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire comprising a pair of bead portions provided with bead cores, and a carcass in which side portions are folded around the respective bead cores and extend toroidally between the bead cores. The present invention proposes a technique for preventing the occurrence of wild wires and reducing the weight of a tire without reducing the production efficiency of a bead core that exhibits a predetermined function.

In general, a bead core disposed in a bead portion of a pneumatic tire, as described in Patent Document 1, for example, winds one or more bead wires made of, for example, steel in the tire circumferential direction and in the radial direction. Overlapping can be formed as a bundle of bead wires.
And the bead core formed in this way, for example, in the state where it is arranged with the bead filler on both ends of the cylindrical carcass band molded on the drum, each end portion of the carcass band is Folding the bead core and bead filler back to the center part of the cylinder and pasting unvulcanized sidewall rubber etc. on the carcass band, the diameter of the center part of the carcass band is expanded and deformed. By attaching various tire components such as unvulcanized belt material and tread rubber material, it contributes to the molding of raw tires.

  By the way, when placing the bead core on the end of the carcass band, the bead wires are aligned and arranged because there is only a slight difference between the inner diameter of the ring-shaped bead core and the outer diameter of the cylindrical carcass band. When the bead core is fitted and arranged around the end of the carcass band, the winding start end of the wire constituting the bead core is caught on the end of the carcass band, and the winding start end may jump up from the bead core. When a raw tire is molded in a state in which the winding start end of the bead wire is raised, and a product tire is manufactured through vulcanization, the bead wire winding that jumps up from the bead core while the product tire is mounted on a vehicle and used. The phenomenon that the starting edge breaks through the side rubber and emerges from the side part to the outside, so-called “wild wire” is likely to occur. There was.

In order to prevent the bead wire from jumping up in the tire molding process, which causes the occurrence of such a wild wire, for example, as described in Patent Document 2, a binding member that restrains the bead wire to be bundled is provided. A method of providing a plurality of locations in the circumferential direction of the bead core is widely adopted.
As a result, when the bundle of bead wires constituting the bead core is constrained by a bundling member, even when the bead core is fitted to the end of the carcass band, even if the winding start end of the bead wire contacts the end of the carcass band, It is difficult for the winding start end to jump up, and it is possible to prevent the occurrence of wild wires when using the tire.

JP 2009-023502 A JP 2009-0422202 A

In the above bead core, the bundling member that restrains the bundle of bead wires can suppress the jumping of the bead wire in the tire molding process and can prevent the occurrence of wild wires when using the tire. Since the bead core is formed by winding the bead wire, the winding start end of the bead wire may still jump up from the bead core depending on the arrangement position of the binding member in the circumferential direction of the bead core.
In addition, in this method of forming a bead core by bundling bead wires with a bundling member, it is necessary to prepare a bundling member as a secondary material in advance, which has the problem of increasing costs, and the bead core is molded on a drum. Prior to disposing them on both ends of the cylindrical carcass band, a process of restraining the bundle of bead wires with a bundling member is required, resulting in a problem that the production efficiency of the bead core is lowered.

  On the other hand, in recent years, in order to improve the fuel efficiency of vehicles, it is desired to reduce the weight of pneumatic tires themselves. A bead core in which conventional bead wires made of steel cord or the like are wound and further bead wires are bundled by a binding member. Again, there is a need for weight reduction.

  An object of the present invention is to solve these problems of the prior art, and the object of the present invention is to provide a bead core that exhibits a predetermined function sufficiently inexpensively without the occurrence of wild wires. Moreover, it is an object of the present invention to provide a pneumatic tire that can be produced without lowering the production efficiency and that can effectively reduce the weight of the bead core.

A pneumatic tire according to the present invention includes a pair of bead portions each having a bead core disposed therein, and a carcass in which a side portion is folded around each bead core and extends in a toroidal shape between both bead cores. in the pneumatic tire, the bead core, the tire and the circumferential direction in one of the hollow annular member to successive endless, Ri Na constituted by a reinforcing member provided in the hollow portion thereof, said hollow annular member, regular octagonal Cross section having a square cross-sectional shape, and the reinforcing member can be divided into one regular octagon smaller than the regular octagon of the hollow annular member and four non-regular octagons surrounding the regular octagon. It has a shape .
Here, in the pneumatic tire of the present invention, in the transverse cross section of the bead core, four sides located every other side among the eight sides of the regular octagon forming the inner contour line of the hollow annular member are respectively The non-regular octagonal portion of one of the eight non-regular octagons that forms one outer contour line of the non-regular octagonal portion of the reinforcing member is in contact with one side, and the non-regular octagonal portions of the two adjacent reinforcing members are One side of the eight sides forming each outer contour line of the square part is in contact with each other, and every other side of the eight sides of the regular octagon forming the outer contour line of the regular octagonal part of the reinforcing member The four sides that are positioned are in contact with one of the eight sides of the non-regular octagon that forms one outer contour line of the non-regular octagonal portion of the reinforcing member.

Preferably, in the cross section of the bead core, the regular octagon of the hollow annular member and the regular octagonal portion of the reinforcing member have the same center point, and the regular octagon of the hollow annular member, the reinforcing member When the internal angle is 135 ° in all of the regular octagonal portion of the non-regular octagonal portion of the reinforcing member, and the length of one side of the regular octagon forming the inner contour line of the hollow annular member is 77, The length of one side of the regular octagon forming the outer contour line of the regular octagonal portion of the reinforcing member is 33, and the eight sides forming the outer contour line of the non-regular octagonal portion of the reinforcing member are opposed to each other. The length of one pair of sides is 21, the length of another pair of opposing sides is 77, and the length of two opposing pairs of sides is 23.

  In the pneumatic tire according to the present invention, the bead core is configured by providing a reinforcing member in the hollow portion of a single hollow annular member that is endlessly continuous in the tire circumferential direction. Therefore, when the tire bead portion is moved over the rim flange, the bead core tensile rigidity against the force acting in the direction of expanding the ring-shaped bead core in the circumferential direction and when the tire is assembled to the rim for use. The conventional method is to wind the wire by securing the torsional rigidity of the bead core against the external force acting on the bead core, i.e., the tension acting in the direction in which the carcass is pulled out in the cross section of the tire width at the time of air filling, load application etc. Similar to the bead core, the bead core can sufficiently exhibit a predetermined function.

  Also, according to this bead core, the endless hollow circular tubular member does not cause a phenomenon that the winding start end of the bead wire jumps up at the time of green tire molding, thereby completely preventing the occurrence of wild wires. This bead core can be easily manufactured by molding a tubular body in which a reinforcing member is housed in a hollow part into an annular shape, and butting both ends of the tubular body together. Can be effectively removed.

  Moreover, this bead core has a larger bead core weight than a conventional bead core formed by winding a bead wire, which mainly has a hollow portion and therefore has the same surrounding area of the outer outline of the cross section. The weight of the bead core can be reduced.

  Here, when the reinforcing member provided in the hollow portion of the bead core is an internal reinforcing wall that has a honeycomb cross-sectional shape and is continuous over the entire circumference of the hollow annular member, while reducing the weight of the bead core, The above-described tensile rigidity and torsional rigidity of the bead core can be further increased, and the predetermined function of the bead core can be more fully exhibited.

1 is a cross-sectional view in the width direction showing one embodiment of the present invention with respect to a tire half portion. It is a perspective view of the bead core of the state taken out from the pneumatic tire of this invention. It is width direction sectional drawing which shows other embodiment about the principal part. It is width direction sectional drawing which shows other embodiment about the principal part. It is a side perspective view which illustrates the process of arrange | positioning a bead core on the edge part part of a carcass band. It is an expanded sectional view which follows the AA line of FIG. It is a width direction sectional view which illustrates the division rim applied to the pneumatic tire of this invention. (A), (b) is the width direction sectional drawing of the bead core arrange | positioned at the Example tire and the conventional example tire, respectively.

Embodiments of the present invention will be described below with reference to the drawings.
In the place shown in FIG. 1, a pneumatic tire 1 has a pair of bead portions 3 each having a bead core 2 and side portions folded around the bead cores 2, and a toroid between the bead cores 2. The carcass 4 extending in the shape of the carcass 4, the belt 5 composed of one or more layers, in the drawing, two belt layers, and the tread disposed further radially outward of the belt 5. With rubber 6.

  Here, the carcass 4 can be composed of, for example, one or more carcass plies formed by extending an organic fiber cord in the radial direction. The illustrated carcass 4 is a single carcass ply having a radial structure. Consists of.

Here, as shown in FIGS. 1 and 2, the bead core 2 disposed in the bead portion 3 includes a single hollow annular member 7 that is endlessly continuous in the tire circumferential direction, and a hollow of the hollow annular member 7. It is comprised by the reinforcement member 8 accommodated and arrange | positioned in the part.
In FIG. 1, the inner and outer contour shapes in the cross section of the hollow bead core 2 are both circular, but the cross-sectional shapes are as shown in FIGS. 3 (a) to 3 (c). Both of the contour shapes may be polygons such as a quadrangle, a hexagon, or an octagon.
Note that the inner and outer contour shapes in the cross section can be different from each other.

  The reinforcing member 8 is disposed in the hollow portion of the hollow annular member 7 for the purpose of ensuring the above-described tensile rigidity and torsional rigidity of the bead core 2 and exhibiting a predetermined function of the bead core. The reinforcing member 8 is formed of a reinforcing cloth such as a carbon fiber woven cloth or an aramid fiber woven cloth adhered to the inner surface of the hollow portion of the hollow annular member 7 over the entire circumference thereof.

  The bead core 2 having such a configuration is obtained by, for example, reinforcing a plate-like member after uniformly attaching a reinforcing fabric such as a carbon fiber woven fabric to one surface of a flat plate-like member made of steel by adhesion or the like. It is formed into a cylindrical shape with the cloth sticking surface as the inner surface, and further joined together by welding means such as welding by joining both ends of the cylindrical body into a continuous ring shape in the circumferential direction. Can be molded.

By the way, the reinforcing member 8 is constituted by an internal reinforcing wall made of a plurality of hollow materials, which is housed and disposed inside the hollow annular member 7 without a gap, as illustrated in a cross-sectional view in FIG. In this case, it is preferable that the cross-sectional shape of the internal reinforcing wall has a honeycomb shape as illustrated in FIG.
Here, the “honeycomb shape” refers to a shape in which regular hexagons are arranged without gaps.

  According to the bead core 2 including the internal reinforcing wall whose cross-sectional shape forms a honeycomb shape, the presence of the hollow space can achieve a reduction in weight of the bead core 2 as compared with a conventional bead core formed by winding wires. At the same time, it is possible to sufficiently ensure the tensile rigidity and torsional rigidity required for the bead core and further improve the predetermined function.

  Such a bead core 2 having the reinforcing member 8 as a reinforcing wall is formed, for example, by forming a single solid rod-like member into a hollow cylindrical shape by cutting or the like, while specifying a dimension so as to coincide with the hollow portion in advance. After the reinforcing member 8 configured as described above is inserted into the hollow cylindrical body, both ends of the hollow cylindrical body can be butted and joined, and the steel material is extruded in a molten state, thereby forming a hollow bar shape. It can also be manufactured by integrally forming the inner reinforcing wall together with the member and then butting and joining the both ends in the same manner.

  The bead core 2 having the above-described configuration preferably exhibits a tire circumferential tension of about 3000 KPa in order to sufficiently exhibit its predetermined function when disposed in a tire.

As illustrated in FIG. 5, the bead core 2 formed as described above is adsorbed by a bead holder (not shown), for example, by magnetic force or negative pressure, or mechanically held. By moving from both outer sides in the axial direction toward the center side, the cylindrical carcass band 10 formed on the molding drum 9 is positioned and arranged on both ends indicated by phantom lines in the drawing.
At that time, since the bead core 2 according to the present invention is configured in an endless annular shape, even if the bead core 2 contacts the end portion of the carcass band 10, the bead wire does not jump up. .

  Although not shown in FIG. 5, the bead core 2 is formed in a state in which the ring-shaped bead filler material 11 is adhered and disposed on the outer peripheral surface thereof as shown in an enlarged cross-sectional view in FIG. It is common to position and arrange on both ends of the upper carcass band 10.

Thereafter, each end portion of the carcass band 10 is folded back toward the center of the cylinder so as to wrap the bead core 2 and the bead filler material 11, and unvulcanized sidewall rubber or the like is adhered onto the carcass band. Then, while expanding and deforming the central portion of the carcass band 10, various tire components such as an unvulcanized belt material and a tread rubber material are pasted to form a raw tire, and this raw tire is further vulcanized The product tire 1 is obtained by vulcanization molding with a mold.
According to the product tire 1, it is possible to completely prevent the occurrence of a wild wire due to the jumping up of the bead wire when the raw tire is molded.

By the way, this pneumatic tire 1 is preferably assembled to a split rim.
Here, the divided rim refers to a rim having a structure in which at least one rim flange can be removed from the rim body.

  This is because the bead core 2 has a single endless annular shape that is continuous in the tire circumferential direction, so that the amount of expansion and contraction in the circumferential direction of the bead core 2 is larger than that of a conventional bead core formed by winding a wire. This is because it is difficult to assemble the pneumatic tire 1 of the present invention to a general rim that requires the bead portion 3 to get over the rim flange when the rim is assembled.

  7, the lock ring 13, the seat band 14, and the rim flange 15b are sequentially removed, and one bead base of the bead portion 3 is seated on one bead seat 16 of the split rim 12. After that, the rim assembly of the tire 1 is completed by fitting the rim flange 15b and the seat band 14 and fixing them with the lock ring 15, so that it is not necessary to greatly expand the bead portion 3 of the tire 1 in the circumferential direction. It is not necessary for the bead core 2 to get over the rim flange 15 and the rim assembly of the tire 1 is facilitated.

  Next, the pneumatic tire 1 according to the present invention was prototyped and its performance was evaluated.

  The sizes of the test tires were two types of 1200R20 16PR and 315 / 80R22.5 for each of the example tire and the conventional tire.

  An example tire is a tire 1 including a bead core 2 shown in FIG. 4A in its bead portion 3, and the bead core 2 is continuous over the entire circumference of the hollow tubular member 7 and the hollow annular member 7. And a reinforcing wall composed of a plurality of hollow members.

  As shown in an enlarged cross-sectional view in FIG. 8A, the outer and inner contour shapes of the hollow circular tubular member 7 are both regular octagons and the reinforcing member 8 is a hollow circular tubular member 7. The configuration is a combination of a regular octagonal hollow member located at the center of the cross section and an octagonal hollow member located around the hollow member.

  The bead core 2 was manufactured by extruding a steel material in a molten state and integrally forming the reinforcing member 8 together with the hollow rod-shaped member 7 and then butting and joining both ends thereof.

  In the conventional tire, instead of the bead core 2, as shown in an enlarged cross-sectional view in FIG. 8B, a bead wire in which a 1.88 mm diameter wire is covered with rubber so that the cross-sectional shape is a hexagon is used as the tire. Constructed in the same way as the tire of the example except that the bead core is formed in the bead portion by being wound in the circumferential direction and wound in the radial direction, and further, this bead wire bundle is constrained by a metal band as a binding member. It is a thing.

  In addition, about structures other than the bead core 2 of an Example tire and a conventional example tire, all are comprised similarly to the tire 1 shown in FIG. 1, and description is abbreviate | omitted.

(Evaluation method)
First, in order to evaluate the presence or absence of the occurrence of wild wires in each test tire, 500 tires each having a tire size of 1200R20 16PR were prepared, and 500 tires of the conventional example were all mounted on the vehicle, and 50,000 km. At each stage after running, after running for 100,000 km and after running for 150,000 km, the presence or absence of wild wires in each test tire was examined.
The results are shown in Table 1.

  Of the 500 tires of the example and the conventional tire, “Yes” was given when there was one that had wild wires, and “None” was given when none of the tires.

Next, before disposing the bead core on each test tire having a tire size of 315 / 80R22.5, a pair of bead cores 2 disposed on the example tire and a pair of bead cores disposed on the conventional tire, The weight of each was measured and the weight reduction of the bead core was evaluated. This weight comparison is based on the cross-sectional area of the bead core that is the same for the example tire and the conventional tire.
As a result, the weight of the pair of bead cores disposed on the conventional tire was 4.0 kg, whereas the weight of the pair of bead cores 2 disposed on the example tire was 2.0 kg.

  Table 1 shows that some of the conventional tires generate wild wires even when running at 50,000 km, whereas the example tires do not generate any wild wires even when running at 150,000 km. Therefore, it has been found that the pneumatic tire 1 of the present invention in which the bead core 2 is disposed does not generate a wild wire even when the pneumatic tire 1 is used in a vehicle and can completely prevent the generation of the wild wire. From the results of the weight measurement, it was found that the weight of the bead core 2 can be greatly reduced as compared with the conventional bead core having the same cross-sectional area in which the bead wires are aligned and arranged.

1: Pneumatic tire 2: Bead core 3: Bead part 4: Carcass 5: Belt 6: Tread rubber 7: Hollow annular member 8: Reinforcement member 9: Drum 10: Carcass band 11: Bead filler 12: Split rim 13: Lock Ring 14: seat band 15a, 15b: rim flange 16: bead seat

Claims (2)

In a pneumatic tire comprising a pair of bead portions provided with bead cores, and a carcass in which side portions are folded around the respective bead cores and extend toroidally between the bead cores,
Bead core, a single hollow annular member continuously endlessly in the circumferential direction of the tire, Ri Na constituted by a reinforcing member provided in the hollow portion thereof,
The hollow annular member has a regular octagonal cross-sectional shape, and the reinforcing member includes one regular octagon smaller than the regular octagon of the hollow annular member, and four non-regular octaves surrounding the regular octagon. Having a cross-sectional shape that can be divided into squares;
Here, in the cross section of the bead core,
Of the eight sides of the regular octagon that forms the inner contour line of the hollow annular member, the four sides that are located at every other side are the non-contour lines that form one outer contour line of the non-regular octagonal portion of the reinforcing member. It touches one of the eight sides of the regular octagon,
For the non-regular octagonal portions of the two adjacent reinforcing members, one of the eight sides forming the respective outer contour lines of the non-regular octagonal portions is in contact with each other,
Of the eight sides of the regular octagon that forms the outer contour line of the regular octagonal portion of the reinforcing member, four sides located at every other side are one outer contour line of the non-regular octagonal portion of the reinforcing member, respectively. A pneumatic tire in contact with one of the eight sides of the non-regular octagon . In the cross section of the bead core,
The regular octagon of the hollow annular member and the regular octagonal portion of the reinforcing member have the same center point,
In all of the regular octagon of the hollow annular member, the regular octagonal portion of the reinforcing member, and the non-regular octagonal portion of the reinforcing member, the internal angle is 135 °,
When the length of one side of the regular octagon forming the inner contour line of the hollow annular member is 77,
The length of one side of the regular octagon forming the outer contour line of the regular octagonal portion of the reinforcing member is 33, and the eight sides forming the outer contour line of the non-regular octagonal portion of the reinforcing member are opposed to each other. 2. The pneumatic tire according to claim 1, wherein the pair of sides has a length of 21, another pair of opposite sides has a length of 77, and two pairs of opposite sides have a length of 23 .

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