JP2018069887A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of improving productivity in formation of a bead core.SOLUTION: In a pneumatic tire, the bead parts are provided inside the respective side wall parts in a tire radial direction, and a carcass layer is arranged straddling from one to the other of bead parts having the bead cores and provided at both sides in a tire width direction. According to an objective tire production technique, plural bead wires 11a composing the bead core are arranged in single string through the butting parts 11b at which mutual end parts of the bead wires are butted and wound in a tire circumferential direction to form the tire.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire.

  For example, Patent Document 1 describes a pneumatic tire having a bead core. In this pneumatic tire, a bead core includes a central core made of a lightweight metal material and a plurality of sheathed steel wires that wrap around the central core. The central core is welded at both ends to form one continuous ring.

  Further, for example, Patent Document 2 describes a pneumatic tire having a bead core. In this pneumatic tire, the bead core is formed by winding one or more bead cords, and provided with a surface that is mutually aligned with each of adjacent bead cords in at least a part of the cross-section of the bead core. All are fixed by soldering or adhesive.

Japanese Patent No. 4304348 Japanese Patent No. 5623736

  By the way, the bead core is generally configured by winding a single bead wire. That is, in manufacturing, the bead core is formed by winding a continuous bead wire. For this reason, when the bead wire for forming one bead core is less than the required length, the bead wire is discarded without being used, and there is a problem that productivity is deteriorated.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve productivity in forming a bead core.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention is configured such that a plurality of bead wires are arranged in series via abutting portions where the ends of each other are abutted, and the tire circumferential direction A bead core formed by being wound around.

  According to this pneumatic tire, it is possible to form a bead core without producing a bead wire end as much as possible at the time of manufacturing the bead core. As a result, productivity can be improved in forming the bead core.

  In the pneumatic tire according to one aspect of the present invention, it is preferable that the plurality of bead wires have a joint portion where the abutting portions are joined and are connected to one.

  According to this pneumatic tire, the strength of the bead core can be improved and durability can be ensured by connecting the plurality of bead wires to one by providing the joint portion.

  In the pneumatic tire according to one aspect of the present invention, the bead core has a midpoint of a straight line connecting a point that protrudes most outward in the tire width direction and a point that protrudes most inward in the tire width direction in the meridional section. It is preferable that all of the abutting portions are arranged in an outer region in the tire width direction with a center line passing through and extending in the tire radial direction as a boundary.

  According to this pneumatic tire, the outer region in the tire width direction of the bead core collides with the outer region in the tire width direction because tension and strain generated in the bead wire when the air pressure is filled are smaller than those in the inner region in the tire width direction. By disposing all of the portions, it is possible to secure the durability performance by suppressing the decrease in the durability performance of the bead portion.

  In the pneumatic tire according to one aspect of the present invention, it is preferable that the bead wire has a meridional cross-sectional area in the abutting portion of 90% to 115% of a meridional cross-sectional area in a portion other than the abutting portion.

  According to this pneumatic tire, the meridional cross-sectional area at the abutting portion is in the range of 90% to 115% of the meridional cross-sectional area at the portion other than the abutting portion, thereby suppressing the collapse of the winding shape of the bead wire forming the bead core. Thus, the winding shape of the bead wire can be maintained. As a result, the durability can be ensured by suppressing the decrease in the durability.

  Further, in the pneumatic tire according to one aspect of the present invention, the bead core has a butt portion of 90 when the position in the tire circumferential direction of at least one end of the bead wires arranged in series is 0 degree. It is preferably arranged at a position not less than 270 ° and not more than 270 °.

  According to this pneumatic tire, the position of the abutting portion can be kept at a constant distance with respect to the end position of the bead wires arranged in series. As a result, it is possible to avoid coincidence of the end position of the bead wire in the tire circumferential direction, and it is possible to secure durability performance by suppressing a decrease in durability performance.

  In the pneumatic tire according to one aspect of the present invention, it is preferable that the bead wire has a wire diameter of φ1.2 mm or more and φ2.0 mm or less.

  According to this pneumatic tire, by setting the wire diameter of the bead wire to φ1.2 mm or more, it is possible to maintain the durability of the single wire while maintaining the strength of the single wire. In addition, when the wire diameter of the bead wire is set to φ2.0 mm or less, it is possible to suppress the situation where the degree of difficulty in joining becomes high and to ensure productivity.

  In the pneumatic tire according to one aspect of the present invention, the bead wire is preferably a steel wire having a single wire strength of 2.2 kN or more.

  According to this pneumatic tire, by setting the single wire strength of the bead wire to 2.2 kN or more, the strength of the single wire can be maintained and the durability performance can be ensured.

  According to the present invention, productivity can be improved in forming a bead core.

FIG. 1 is a meridional sectional view of a bead portion of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a meridional sectional view of the bead core of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is a partially enlarged view of the bead wire of the pneumatic tire according to the embodiment of the present invention. FIG. 4 is a partially enlarged view of another example of the bead wire of the pneumatic tire according to the embodiment of the present invention. FIG. 5 is a schematic side view of the bead portion of the pneumatic tire according to the embodiment of the present invention. FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  FIG. 1 is a meridional sectional view of a bead portion of a pneumatic tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire width direction refers to a direction parallel to the rotation axis, the inner side in the tire width direction is the side toward the tire equatorial plane (not shown) in the tire width direction, and the outer side in the tire width direction is in the tire width direction. The side away from the tire equator. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the radial direction is a direction including the tire radial direction and the tire width direction along the meridian direction orthogonal to the tire equatorial plane. The tire equator plane is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane in the tire width direction.

  As shown in FIG. 1, a pneumatic tire (heavy duty pneumatic tire) 1 has a tire diameter from an end portion in a tire width direction of a tread portion (not shown) formed in an outermost portion in the tire radial direction. A sidewall portion 5 is provided up to a predetermined position inside the direction. That is, the sidewall portions 5 are provided at two locations of the pneumatic tire 1 and are provided at symmetrical positions with respect to the tire equatorial plane on both outer sides in the tire width direction. Further, the pneumatic tire 1 is provided with a bead portion 10 on the inner side in the tire radial direction of each sidewall portion 5. The bead part 10 is provided in two places of the pneumatic tire 1 like the side wall part 5, and is provided in a symmetrical position with respect to the tire equatorial plane on both outer sides in the tire width direction.

  The bead unit 10 has a bead core 11. The bead core 11 is formed by winding a bead wire 11a (see FIG. 2), which is a steel wire, in a ring shape along the tire circumferential direction. Also, the bead portion 10 is formed as a bead base 12 on the inner side in the tire radial direction. The bead base 12 is a portion located on the inner side in the tire radial direction of the bead core 11 and in contact with a rim (not shown). In the bead portion 10, a bead filler 13 is disposed outside the bead core 11 in the tire radial direction. The bead filler 13 includes a lower bead filler 13a near the bead core 11 and an upper bead filler 13b on the outer side in the tire radial direction.

  In the pneumatic tire 1, a carcass layer 20 is provided on the tread portion, the sidewall portion 5, and the bead portion 10. The carcass layer 20 is continuously disposed in the tire circumferential direction, and carcass cords extending in the radial direction and arranged in the tire circumferential direction are covered with a covering material made of a rubber material. The carcass layer 20 is disposed from one bead portion 10 to the other bead portion 10 among the bead portions 10 provided on both sides in the tire width direction. Further, the carcass layer 20 has a turn-up structure in which the bead portion 10 is folded around the bead core 11 from the inner side to the outer side in the tire width direction of the bead core 11.

  That is, as shown in FIG. 1, the carcass layer 20 is directed from the sidewall portion 5 to the bead portion 10, passes from the inner side in the tire width direction of the bead core 11 to the inner side in the tire radial direction of the bead core 11, and further in the tire width direction of the bead core 11. It passes outside. In the carcass layer 20, a portion located outside the bead core 11 in the tire width direction is a turn-up portion 21, and an end portion of the turn-up portion 21 on the outer side in the tire radial direction is an end portion of the carcass layer 20. A carcass layer end 22 is formed. The end portion 22 of the carcass layer is located on the outer side in the tire radial direction than the bead core 11, and is located on the outer side in the tire width direction of the upper bead filler 13b in the present embodiment.

  In the pneumatic tire 1, a steel reinforcing layer 30 is provided on the bead portion 10. The steel reinforcing layer 30 is disposed on the outer side of the carcass layer 20 so as to be overlapped with the carcass layer 20, and is folded around the bead core 11 from the inner side to the outer side in the tire width direction and continuously disposed in the tire circumferential direction. In the steel reinforcing layer 30, a plurality of steel cords crossing the carcass cord are covered with a covering material made of a rubber material. For example, the steel cord is disposed on the inner side in the tire radial direction of the bead core 11 with an angle of −70 [°] or +70 [°] with respect to the radial direction along which the carcass cord extends.

  As shown in FIG. 1, the steel reinforcing layer 30 is located inside the carcass layer 20 in the tire width direction in the bead portion 10 where the carcass layer 20 is located inside the bead core 11 in the tire width direction. ing. Further, the steel reinforcing layer 30 is located on the inner side in the tire radial direction of the carcass layer 20 in a portion where the carcass layer 20 is located on the inner side in the tire radial direction from the bead core 11. Further, the steel reinforcing layer 30 is located on the outer side in the tire width direction of the carcass layer 20 in a portion where the carcass layer 20 is located on the outer side in the tire width direction with respect to the bead core 11.

  Further, in the steel reinforcing layer 30, the end portion on the tire radial direction outer side of the portion located on the inner side in the tire width direction than the bead core 11 is the steel reinforcing layer inner end portion 31, and the steel width in the tire width direction than the bead core 11. An end portion on the outer side in the tire radial direction of the portion located on the outer side is a steel reinforcing layer outer end portion 32. In other words, the steel reinforcing layer inner end portion 31 is an end portion on the inner side in the tire width direction of the steel reinforcing layer 30, and the steel reinforcing layer outer end portion 32 is an end portion on the outer side in the tire width direction of the steel reinforcing layer 30. . Further, the steel reinforcing layer inner end portion 31 and the steel reinforcing layer outer end portion 32 are both positioned on the outer side in the tire radial direction from the bead core 11. Further, the steel reinforcing layer inner end portion 31 is positioned on the outer side in the tire radial direction from the position of the carcass layer end portion 22, and the steel reinforcing layer outer end portion 32 is on the inner side in the tire radial direction from the position of the carcass layer end portion 22. Is located.

  FIG. 2 is a meridional sectional view of the bead core of the pneumatic tire according to the present embodiment. FIG. 3 is a partially enlarged view of the bead wire of the pneumatic tire according to the present embodiment. FIG. 4 is a partially enlarged view of another example of the bead wire of the pneumatic tire according to the present embodiment. FIG. 5 is a schematic side view of a bead portion of the pneumatic tire according to the present embodiment.

  In the pneumatic tire 1 configured as described above, the bead core 11 is formed by winding a bead wire 11a in the tire circumferential direction as shown in FIG. The bead wire 11a is a single steel wire and is wound in a series in the tire circumferential direction to form the bead core 11. For example, the bead wire 11a is wound in the tire circumferential direction starting from the innermost side in the tire radial direction in FIG. 2 and starting from the innermost side in the tire width direction. The bead core 11 is formed by repeating this process and overlapping the outer side in the tire radial direction.

  In the pneumatic tire 1 of the present embodiment, in such a bead core 11, as shown in FIG. 3, a plurality of bead wires 11 a are used, and through a butting portion 11 b that is faced with each other facing each other. They are arranged in series and are wound in the tire circumferential direction. That is, the bead wire 11a is divided into a plurality of pieces, arranged in series via the abutting portions 11b that face each other and face each other, and are wound in the tire circumferential direction.

  According to this pneumatic tire 1, it is possible to form the bead core 11 without producing the end material of the bead wire 11 a as much as possible at the time of manufacturing the bead core 11. As a result, productivity can be improved in forming the bead core 11.

  Moreover, in the pneumatic tire 1 of this embodiment, as shown in FIG. 4, the some bead wire 11a is connected and provided by having the joining part 11c to which the abutting part 11b was joined. Preferably it is.

  The joining portion 11c joins the plurality of bead wires 11a by welding the abutting portions 11b. Moreover, the joining part 11c may join a plurality of bead wires 11a by bonding with an adhesive other than welding.

  According to the pneumatic tire 1, the strength of the bead core 11 can be improved and the durability performance of the bead portion 10 can be ensured by connecting the plurality of bead wires 11 a to each other with the joint portion 11 c. .

  In the pneumatic tire 1 of the present embodiment, as shown in FIG. 2, the bead core 11 has a point A that protrudes most outward in the tire width direction and a point B that protrudes most inward in the tire width direction in the meridional section. Tire width direction inner side region α and tire width direction outer side region β with a center line CL extending in the tire radial direction passing through the midpoint C of the auxiliary straight line AL connecting It is preferable that all of the abutting portions 11b are arranged at β.

  Here, in the present embodiment, the bead core 11 has a virtual outer shape in the meridional section shown in FIG. 2 by an outer straight line (indicated by a one-dot chain line in FIG. 2) that traces the outer shape of each bead wire 11a. Then, in this outer shape, a point A that protrudes most outward in the tire width direction, a point B that protrudes most inward in the tire width direction, and an auxiliary straight line AL are obtained. In addition, the center line CL is obtained by arranging the bead portions 10 at an interval assembled with a regular rim when the pneumatic tire 1 is not assembled with a rim. Alternatively, the center line CL may be obtained in a state where the pneumatic tire 1 is assembled on a regular rim. The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO.

  In addition, the fact that all of the abutting portions 11b are arranged in the tire width direction outer region β means that all the outer shapes of the abutting portions 11b exist in the tire width direction outer region β in the meridional section. That is, when the center line CL is applied to the outer region of the abutting portion 11b, it is considered that the abutting portion 11b does not exist in the outer region β in the tire width direction.

  According to this pneumatic tire 1, in the bead core 11, the tire width direction outer side region β has less tension and distortion generated in the bead wire 11 a when filled with air pressure than the tire width direction inner side region α. By disposing all the abutting portions 11b in the width direction outer side region β, it is possible to suppress the decrease in the durability performance of the bead portion 10 and to ensure the durability performance of the bead portion 10.

  In the pneumatic tire 1 of the present embodiment, the bead wire 11a preferably has a meridional cross-sectional area at the abutting portion 11b of 90% to 115% of a meridional cross-sectional area at a portion other than the abutting portion 11b.

  The meridional cross-sectional area in the abutting portion 11b corresponds to the area of the end face where the plurality of bead wires 11a are abutted. The meridional cross-sectional area at the abutting portion 11b corresponds to the meridional cross-sectional area at the joint portion 11c where the abutting portion 11b is joined.

  According to this pneumatic tire 1, the bead core 11 is formed by setting the meridional cross-sectional area in the abutting portion 11b (joining portion 11c) to a range of 90% to 115% of the meridional cross-sectional area in a portion other than the abutting portion 11b. The collapse of the winding shape of the bead wire 11a can be suppressed and the winding shape of the bead wire 11a can be maintained. As a result, it is possible to ensure the durability performance of the bead portion 10 by suppressing a decrease in the durability performance of the bead portion 10. If it deviates from the above range, the winding shape of the bead wire 11a tends to collapse.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 5, the bead core 11 has a position in the tire circumferential direction of at least one end portion of the bead wires 11 a arranged in series as 0 degrees. The abutting portion 11b (joining portion 11c) is preferably disposed at a position of 90 ° or more and 270 ° or less.

  Here, it is preferable that the bead core 11 aligns the positions in the tire circumferential direction at both ends of the bead wires 11a arranged in series at 0 degrees.

  According to this pneumatic tire 1, the position of the abutting portion 11b (joining portion 11c), which is the end portion of the bead wires 11a arranged in series, for example, relative to the winding start position can be maintained at a constant distance. As a result, the end position of the bead wire 11a can be prevented from matching in the tire circumferential direction, and a decrease in the durability performance of the bead portion 10 can be suppressed to ensure the durability performance of the bead portion 10.

  In order to suppress a decrease in durability performance of the bead portion 10 by separating the end portion position of the bead wire 11a as much as possible in the tire circumferential direction, the position in the tire circumferential direction of at least one end portion of the bead wires 11a arranged in series is determined. When it is 0 degree, it is more preferable that the abutting portion 11b (joining portion 11c) is disposed at a position of 135 ° or more and 225 ° or less.

  Moreover, each end part of the bead wire 11a arrange | positioned in series is stopped by the circumference | surroundings in a meridian cross section as shown in FIG. 2 being coat | covered with rubber | gum.

  In addition, when there are a plurality of the abutting portions 11b (joining portions 11c), it is preferable that the abutting portions 11b (joining portions 11c) are also arranged apart from each other in the tire circumferential direction.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the bead wire 11a has a wire diameter of φ1.2 mm or more and φ2.0 mm or less.

  According to this pneumatic tire 1, the durability of the bead portion 10 can be ensured while maintaining the strength of the single wire by setting the wire diameter of the bead wire 11a to φ1.2 mm or more. In addition, when the wire diameter of the bead wire 11a is set to φ2.0 mm or less, it is possible to prevent productivity from increasing when the joining (welding) is performed, thereby ensuring productivity.

  In addition, in order to ensure the durability performance of the bead part 10 and to ensure productivity, it is more preferable that the wire diameter of the bead wire 11a is φ1.4 mm or more and φ1.7 mm or less.

  In the pneumatic tire 1 of the present embodiment, the bead wire 11a is preferably a steel wire having a single wire strength of 2.2 kN or more.

  The single wire strength conforms to the cutting load described in JIS G 3510-1992.

  According to this pneumatic tire 1, the durability of the bead portion 10 can be ensured by maintaining the strength of the single wire by setting the single wire strength of the bead wire 11 a to 2.2 kN or more.

  In the above-described embodiment, a heavy duty pneumatic tire is illustrated as the pneumatic tire 1, but is not limited thereto. That is, the pneumatic tire 1 may be a passenger vehicle pneumatic tire. However, it is preferable to apply the pneumatic tire 1 to a heavy duty pneumatic tire in order to secure durability while improving productivity when forming a bead core.

  In this example, performance tests regarding productivity and durability performance of the bead portion were performed on a plurality of types of pneumatic tires having different conditions (see FIGS. 6 and 7).

  Evaluation of productivity is judged by whether or not the end material of the bead wire is generated at the time of manufacturing the bead core. The case where the end material is generated is indicated by x, the case where the end material is not generated is indicated by ◯, and the case where the end material is not generated is indicated by ◯, indicating that the productivity is higher and superior.

  In the performance test of durability performance, a pneumatic tire with a tire size of 225 / 80R17.5 is assembled with a regular rim, and filled with pressurized water gradually, and the pressure when the tire breaks is measured. The Then, based on the measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation shows that durability performance is ensured, so that a numerical value is close to 100 and is 95 or more.

  In FIG. 6, the conventional pneumatic tire has a configuration in which one bead wire is continuous. On the other hand, in FIG. 6, the pneumatic tire of Example 1 and Example 2 has two bead wires arranged in series via one butted portion. Moreover, in FIG. 6 and FIG. 7, as for the pneumatic tire of Example 3-Example 16, the butt | matching part is joined by the junction part (welding). All pneumatic tires are steel wires with a bead wire single wire strength of 2.5 kN.

  As shown in the test results of FIGS. 6 and 7, it can be seen that the pneumatic tires of Examples 1 to 16 have improved productivity and ensured durability performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 10 Bead part 11 Bead core 11a Bead wire 11b Butt part 11c Joint part

Claims (7)

  A pneumatic tire having a bead core in which a plurality of bead wires are arranged in series via a butted portion that abuts each other and wound around the tire in the circumferential direction.   2. The pneumatic tire according to claim 1, wherein the plurality of bead wires have a joint portion to which the abutting portions are joined and are connected to each other.   In the meridional section, the bead core has a central line extending in the tire radial direction passing through a midpoint of a straight line connecting a point that protrudes most outward in the tire width direction and a point that protrudes most inward in the tire width direction. The pneumatic tire according to claim 1 or 2, wherein all of the abutting portions are arranged in an outer region in the tire width direction.   The pneumatic tire according to any one of claims 1 to 3, wherein the bead wire has a meridional cross-sectional area at the abutting portion of 90% to 115% of a meridional cross-sectional area at a portion other than the abutting portion.   The bead core is disposed at a position where the abutment portion is 90 ° or more and 270 ° or less when a position in the tire circumferential direction of at least one end portion of the bead wires arranged in series is 0 °. The pneumatic tire as described in any one of -4.   The pneumatic tire according to claim 1, wherein the bead wire has a wire diameter of φ1.2 mm or more and φ2.0 mm or less.   The pneumatic tire according to any one of claims 1 to 6, wherein the bead wire is a steel wire having a single wire strength of 2.2 kN or more.

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