JPH08216633A - Bead structure of tire and method of manufacturing tire - Google Patents

Abstract

PURPOSE: To prevent the air trapping during assembling of a tire so as to pre vent the deterioration in RFV level and durability of the tire by providing radial ledges which extend from a bead base to a rim fitting surface along the radial direction of the tire and project sideward. CONSTITUTION: A purularity of radial ledges 8 are provided on a bead portion 2 of a tire 1 in such a manner that the ledges 8 extend on a rim fitting surface 6 from 2 bead base 5 to the rim fitting surface 6 along the radial direction of the tire 1 with a predetermined distance. On the bead base 5 an internal circular ledge 9 is provided while on the rim fitting surface 6 an outernal one 10. Internal ends of the radial ledges 8 are connected to the internal circular ledges 9, and outernal ends of those 8 to the outernal one 10. Clearances X and Y formed therein decrease with air charging into the tire 1, allowing air to be possibly trapped to be driven out naturally through the clearances X and Y.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire bead structure and a tire manufacturing method.

[0002]

2. Description of the Related Art At the time of manufacturing a tubeless tire, a hole-like defect (A
B) and worm-eaten defects (VB) mainly caused by rubber flow failure (air accumulation) are often generated. On the other hand, when the tubeless tire was incorporated into a wheel, air was sometimes trapped between the bead portion of the tire and the rim of the wheel and remained as a minute air pool. In most cases, this is due to a failure in assembling work. Incidentally, as a means for solving such a problem at the time of assembling, there is a conventional method disclosed in Japanese Patent Laid-Open No.
No. 40221 or Japanese Patent Application Laid-Open No. 6-40222 discloses a technique, but all of these techniques limit the correlation between the bead portion of the tire and the rim shape of the wheel, and The cross-sectional shape and rubber hardness are devised. Therefore, not only when the tire and the wheel have a non-correlated (other than setting) combination, but also what is effective in solving the problem (defect occurrence) at the time of tire manufacturing as described above. is not.

[0003]

Various defects (AB, VB, etc.) that occur in the bead portion during tire manufacturing reduce the durability of the tire and, in some cases, lose the commercial value (that is, reduce the yield). It was something that caused it. Also, R
It could also be a cause of worsening FV (Radial Force Variation) level.

[0006] Needless to say, the air pockets generated when the tire is incorporated into the wheel have been a cause of deteriorating the RFV level and the durability of the tire. It goes without saying that if the RFV level deteriorates, the traveling vibration increases and the riding comfort deteriorates. The present invention has been made in view of the above circumstances, and various defects that occur in the bead portion during tire production, and problems caused by air pockets that occur when the tire is incorporated into a wheel are eliminated at once. It is an object of the present invention to provide a bead structure of a tire, which can prevent deterioration of RFV level and tire durability, and can improve yield in tire manufacturing, and a method of manufacturing the tire.

[0005]

In order to achieve the above object, the present invention takes the following technical means. That is, the structure of the bead portion of the tire according to the present invention is characterized in that a radial ridge extending in the tire radial direction and laterally is formed between the bead base and the rim fitting surface. .

It is preferable that a plurality of the radial ridges are provided at predetermined intervals in the circumferential direction with respect to the rim fitting surface of the bead portion. The bead base is formed with an inner peripheral ridge protruding inward in the radial direction along the circumferential direction in the width direction, and an inner end of the radial ridge is formed with respect to the inner peripheral ridge. A connected configuration is preferable.

The bead portion is formed with an outer peripheral ridge protruding circumferentially and laterally in the vicinity of the outer peripheral edge of the rim flange during rim fitting, and the radial ridge is formed with respect to the outer peripheral ridge. It is also possible to adopt a configuration in which the outer ends of the are connected. It is preferable that the radial protrusions and the inner peripheral protrusions are formed to have a height of 0.2 mm or more and 3.0 mm or less.

On the other hand, in the method for manufacturing a tire according to the present invention, a rubber flow promoting passage extending in the radial direction from the bead base molding surface to the rim fitting surface molding surface is previously provided in the bead mold used for tire molding. This is characterized in that the radial ridges are formed in conformity with the rubber flow promoting passage during vulcanization molding.

[0009]

In the tire bead structure according to the present invention,
If a radial ridge is provided between the bead base and the rim fitting surface, when the tire is installed in the wheel, the radial ridge is initially projected between the bead portion of the tire and the rim flange of the wheel. A gap corresponding to the height is formed. The gap disappears as the radial ridge is crushed at the time when the tire internal pressure is set to a predetermined pressure (when the bead portion is fitted to the rim of the wheel). At this time, the air that is about to be trapped between the bead portion of the tire and the rim flange of the wheel passes through the gap to the outside in the radial direction of the rim fitting surface (that is, the outside side of the tire) without difficulty. It will be pushed out.

In order to surely obtain such an air pushing effect, it is advantageous to provide a plurality of the radial ridges at predetermined intervals in the circumferential direction. If an inner peripheral ridge is provided for the bead base and this inner peripheral ridge is connected to the inner end of the radial ridge, the tire internal pressure is increased after the tire is installed in the wheel. Air leakage is less likely to occur at the stage, and the work of inflating the tire can be performed easily.
In addition, since the ridges in the radial direction are reinforced, there is an advantage that the initial gap formation can be ensured.

By providing an outer peripheral ridge at a position radially outward of the rim fitting surface, that is, near the outer peripheral edge of the rim flange, and connecting the outer peripheral ridge to the outer end of the radial ridge, the tire It is possible to improve the sealing property after the internal pressure is set to a predetermined pressure. It also reinforces the radial projections. If the protruding heights of the radial ridges and the inner peripheral ridges are less than 0.2 mm, the initial gap formation may not be possible. If it exceeds 3.0 mm, the crushing will be incomplete even if the tire internal pressure is a predetermined pressure,
Air leakage may occur. Therefore, 0.2 mm
It is preferable that the length is not less than 3.0 mm.

In the tire manufacturing method according to the present invention,
In order to form the radial protrusions as described above, the bead mold is formed in advance with a rubber flow promoting passage facing the radial protrusions. This rubber flow promoting passage can generate a specific bypass flow in the rubber flow during vulcanization molding, and realize a smooth rubber flow as a whole. Therefore, it is possible to prevent air entrapment and rubber flow failure and prevent occurrence of various defects (AB, VB, etc.).

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) show a bead portion 2 of a tire 1 according to the present invention. The left side of FIG. 1 (b) is the inside of the tire, the right side thereof is the outside of the tire, and FIG. The upper side is the radially outer side, and the lower side is the radially inner side. 3 is a bead core.

In the bead portion 2 of the tire 1, there are radial ridges 8 extending between the bead base 5 and the rim fitting surface 6, inner bead ridges 9 on the bead base 5, and further on the rim fitting surface 6. Peripheral ridges 10 are provided respectively. The radial ridge 8 projects between the widthwise center position of the bead base 5 and the radial outer position of the rim fitting surface 6 along the radial direction and laterally (outer side of the tire). Is formed. A plurality of radial ridges 8 are provided on the rim fitting surface 6 at predetermined intervals in the circumferential direction. It should be noted that although depending on the rubber quality, tire size, etc., it is preferable that the number of radial ridges 8 is about 4 to 12. Moreover, it is preferable that the mutual intervals (or mutual angles) in the circumferential direction of the radial projections 8 are uniform.

The inner peripheral ridge 9 is formed at the center of the bead base 5 in the width direction (left and right direction in FIG. 1B) so as to extend radially inward along the peripheral direction. However, it is preferable that the inner peripheral protruding line 9 is within the width direction of the bead base 5, and may be displaced to the left or right from the central portion, or provided as a plurality of lines at intervals in the width direction. You can also The inner end of the radial ridge 8 is connected to the inner circumferential ridge 9.

The outer peripheral ridge 10 is located radially outward of the rim line during rim fitting, that is,
It is formed in the vicinity of the outer peripheral edge of the rim flange, along the circumferential direction thereof, and protruding laterally (outer tire lateral side). The outer end of the radial protrusion 8 is connected to the outer peripheral protrusion 10. Since such radial ridges 8, inner peripheral ridges 9 and outer peripheral ridges 10 are provided, as shown in FIG.
When assembling the tire 1 into the wheel 15 as shown in (a), initially, the bead portion 2 of the tire 1 and the wheel 1 are assembled.
5, the clearances X and Y are formed by the radial projection 8 and the inner circumferential projection 9.

These gaps X and Y expand in the process of introducing air into the tire 1, so that the radial ridges 8 and the inner peripheral ridges 9 are expanded as shown in FIG. 2 (b). It shrinks as it is crushed. Then, when the tire internal pressure reaches a predetermined pressure (when the bead portion 2 is fitted to the rim flange 16 of the wheel 15), the radial ridge 8 is formed.
And the inner peripheral ridge 9 is crushed almost completely, and the above-mentioned gaps X and Y disappear. At this time, the air that is about to be trapped between the bead portion 2 of the tire 1 and the rim flange 16 of the wheel 15 is pushed out to the outside in the radial direction of the rim fitting surface 6 through the gaps X and Y without any difficulty. Will be

On the other hand, when the tire internal pressure reaches a predetermined pressure, the inner edge portion of the outer peripheral ridge 10 just contacts the rim line (outer peripheral edge of the rim flange 16) or is lightly pressed inward in the radial direction. It becomes a state. Therefore, a sealing action is obtained at this portion, and it is possible to completely prevent the internal air of the tire 1 from leaking and the entry of mud, sand, dust, and the like into the tire 1.

The outer peripheral ridge 10 is not limited to being in contact with the outer peripheral edge of the rim flange, and may be in a state in which a slight gap remains. Even in such a case, the outer peripheral ridge 10 and the outer peripheral edge of the rim flange 16 come into contact with each other when a vehicle load is applied or when traveling vibration is absorbed, and the above effect can be obtained. By the way, the above-mentioned projection height of the radial ridge 8 (see h1 shown in FIG. 1B) and the projection height of the inner circumferential ridge 9 (see h2 shown in FIG. 1B) are
It is preferable that the thickness is 0.2 mm or more and 3.0 mm or less. These differ to some extent within the above range depending on the rubber quality, the tire size, the application of the tire 1, and the like. However, in the experiment conducted by the inventor of the present invention, 0.3 mm was the optimum in most cases.

The protruding heights h of the radial ridges 8 and the inner peripheral ridges 9
When 1 and h2 are less than 0.2 mm, the gaps X and Y cannot be formed between the bead portion 2 of the tire 1 and the rim 16 of the wheel 15 even if the tire 1 is incorporated into the wheel 15. There is. On the other hand, when the protruding heights h1 and h2 of the radial ridges 8 and the inner circumferential ridges 9 exceed 3.0 mm, even if the tire internal pressure is set to a predetermined pressure, the radial ridges 8 and the inner ridges 9 do not change. Crushing of the circumferential ridge 9 may be incomplete, and air leakage may occur between the bead portion 2 of the tire 1 and the rim flange 16 of the wheel 15.

It is preferable that the protruding height of the outer peripheral ridge 10 is also the same as or slightly larger than that of the radial ridge 8. Regarding the number of the radial ridges 8 to be provided, if the number is less than 4, there is a high possibility that the area where the air pocket is generated may not be provided, and air bleeding may be insufficient. At most,
A bead mold (not shown) used when manufacturing the tire 1 may be troublesome to process, which may lead to an increase in manufacturing cost and a decrease in manufacturing efficiency.

The radial ridges 8, the inner ridges 9, and the outer ridges 10 may have any cross-sectional shape, and may be, for example, a square or a rectangle, a triangle, a semicircle, or the like.
Such radial ridges 8, inner ridges 9, and outer ridges 1
In order to manufacture a tire 1 having 0, a bead mold (not shown) for molding a bead portion 2 is provided with each ridge 8,
The rubber flow accelerating passages (not shown) corresponding to 9 and 10 may be provided beforehand in a recessed manner. For example, a rubber flow promoting passage (not shown) for forming the radial projections 8 has a diameter extending from a molding surface (not shown) for the bead base 5 to a molding surface (not shown) for the rim fitting surface 6. It is formed in a groove shape extending in the direction.

Then, such a bead mold (not shown) is used for molding, and a rubber material is flown into a molding space inside thereof to perform vulcanization molding. In this case, a specific bypass flow accompanies the rubber flow in the mold along each rubber flow promoting passage (not shown), and a smooth rubber flow can be realized in the entire molding space. Become.
Therefore, air entrainment and rubber flow disorder are prevented, and various defects (AB, VB, etc.) are prevented from occurring. Further, at the time of demolding, the radial ridges 8, the inner peripheral ridges 9, and the outer peripheral ridges 10 are left formed in accordance with the respective rubber flow promoting passages (not shown).

Based on the tire manufacturing method according to the present invention, the present inventor manufactured a tubeless tire having a radial ridge 8, an inner peripheral ridge 9, and an outer peripheral ridge 10 to produce various defects (AB, Experiments were performed to compare the conventional tires with respect to the occurrence status of VB) and the RFV level. The tire size was 195 / 60R14 in all cases. The protruding heights h1 and h2 of the radial ridge 8 and the inner peripheral ridge 9 are 0.3.
mm.

As a result, the defect generation rate was 0.08% in the case of the conventional tire manufacturing method, whereas it was 0. 8% in the case of the tire manufacturing method according to the present invention.
It could be reduced to 02%. At the RFV level, the conventional tire had a value of 7.0 kg, while the tire of the present invention was able to suppress it to 5.2 kg.

In the present invention, the radial ridges 8, the inner ridges 9, and the outer ridges 10 are preferably provided on the bead portions 2 on both front and back sides of the tire 1, but only one of them is provided. But it's okay.

[0027]

In the structure of the bead portion of the tire according to the present invention, since the ridge in the radial direction is provided between the bead base and the rim fitting surface, when the tire is assembled into a wheel, the bead portion of the tire is initially provided. Between the wheel and the rim flange of the wheel, a gap corresponding to the protruding height of the radial ridge is formed. The gap disappears as the radial ridge is crushed at the time when the tire internal pressure is set to a predetermined pressure (when the bead portion is fitted to the rim of the wheel). At this time, the air that is about to be trapped between the bead portion of the tire and the rim flange of the wheel passes through the gap to the outside in the radial direction of the rim fitting surface (that is, the outside side of the tire) without difficulty. It will be pushed out. In this way, the occurrence of air accumulation can be prevented, so that the deterioration of the RFV level can be prevented. Therefore, excellent riding comfort can be obtained. Further, tire durability can be improved.

If a plurality of the radial ridges are provided at predetermined intervals in the circumferential direction, the effect can be obtained more reliably and remarkably. If an inner peripheral ridge is provided for the bead base and this inner peripheral ridge is connected to the inner end of the radial ridge, the tire internal pressure is increased after the tire is installed in the wheel. Since air leakage is unlikely to occur at the stage, the work of introducing air into the tire can be performed quickly and easily. In addition, since the ridges in the radial direction are reinforced, there is an advantage that the initial gap formation can be ensured.

By providing an outer peripheral ridge at a position radially outward of the rim fitting surface, that is, near the outer peripheral edge of the rim flange, and connecting the outer peripheral ridge to the outer end of the radial ridge, the tire It is possible to improve the sealing property after the internal pressure is set to a predetermined pressure. Therefore, it is possible to completely prevent the air inside the tire from leaking out and the entry of mud and dust into the tire. It also reinforces the radial projections.

The projecting height of the radial ridge and the inner peripheral ridge is set to 0.
When it is set in the range of 2 mm or more and 3.0 mm or less, there are advantages that the initial gap formation can be reliably performed and air leakage after the tire internal pressure is set to a predetermined pressure is completely prevented. In the tire manufacturing method according to the present invention, in order to form the radial ridges as described above, a rubber flow promoting passage facing the radial ridges is formed in advance in the bead mold. . This rubber flow promoting passage can generate a specific bypass flow in the rubber flow during vulcanization molding, and realize a smooth rubber flow as a whole. Therefore, it is possible to prevent air entrapment and rubber flow failure and prevent occurrence of various defects (AB, VB, etc.). Therefore, it is possible to enhance the durability of the tire and enhance the yield related to the production thereof. It is also effective in preventing the deterioration of the RFV level and enhancing the durability of the tire.

[Brief description of drawings]

1 shows a rim structure of a tire according to the present invention, (a) is a perspective view of a main part, and (b) is an A- line of (a).
FIG. 3 is a sectional view taken along line A.

2A and 2B show a situation in which a tire is incorporated into a wheel, where FIG. 2A is a situation before air is introduced, and FIG. 2B is a situation after the tire internal pressure is set to a predetermined pressure.

[Explanation of symbols]

 1 Tire 2 Bead Part 5 Bead Base 6 Rim-Ficking Surface 8 Radial Convex Line 9 Inner Circumferential Convex Line 10 Outer Convex Line 15 Wheel 16 Rim Flange

Claims (6)

[Claims] 1. In a bead structure of a tire, a radial ridge (8) extending between the bead base (5) and the rim fitting surface (6) along the radial direction of the tire (1) and protruding laterally. ) Is formed in the bead structure of the tire. 2. The plurality of radial ridges (8) are provided at predetermined intervals in the circumferential direction with respect to the rim fitting surface (6) of the bead portion (2). The bead structure of the tire described. 3. The bead base (5) is formed with an inner peripheral ridge (9) projecting radially inward along the circumferential direction in the width direction, and the inner peripheral ridge (9). ) Is connected to the inner end of the radial ridge (8), the bead portion structure of the tire according to claim 1 or 2. 4. The bead portion (2) is formed with an outer peripheral ridge (10) projecting laterally along the circumferential direction near the outer peripheral edge of the rim flange during rim fitting. (10) with respect to the radial ridge (8)
The bead portion structure of the tire according to any one of claims 1 to 3, wherein outer ends of the tire are connected. 5. The height at which the radial ridges (8) and the inner peripheral ridges (9) project is formed to be 0.2 mm or more and 3.0 mm or less. The bead structure of the tire according to claim 4. 6. A vulcanization molding step, wherein a rubber flow accelerating passage extending in a radial direction from a molding surface of a bead base to a molding surface of a rim fitting surface is provided in advance in a bead mold used for molding a tire. A tire manufacturing method characterized in that a radial ridge (8) conforming to the rubber flow promoting passage is formed.