JP2577888B2 - Flat pneumatic bias tire for wheel loader - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to the improvement of carcass durability of pneumatic tires for construction machines traveling on rough terrain, particularly pneumatic bias tires for wheel loaders.

(Prior Art) Tires for construction machinery, particularly pneumatic bias tires for wheel loaders, have a large variety of forces to be transmitted (for example, traction force) in addition to the load burden between the vehicle and the road surface, so that the tire is deformed. The bead is the weakest point of carcass fatigue.

Therefore, in order to improve the durability of the carcass, measures have been taken to increase the number of plies, for example, to increase the rigidity of the entire carcass, or to insert a bead filler to locally increase the rigidity of the bead portion.

(Problems to be Solved by the Invention) However, the above-described conventional technique, that is, an increase in the number of plies or insertion of a bead filler increases the number of members and the amount of members constituting a tire, resulting in an increase in cost. There is.

The present invention improves the above-mentioned drawbacks and provides a carcass structure that improves the durability of the carcass portion without increasing the cost.

(Means for Solving the Invention) The present inventors have made various studies on these and have solved them by adopting the following configuration.

That is, a real ply having an angle of 30 to 40 degrees with respect to the tire circumferential direction has 6 to 14 carcass, and the carcass extends from one bead portion to the other bead portion, and the bead portion forms a bead bundle. A flat pneumatic bias for a wheel loader having excellent durability, characterized in that a ply gauge between a bead wire and a bead base is smaller than a ply gauge at a gooseneck portion in a wheel loader bias tire having a flatness of 0.8 to 0.85. It relates to a tire. Preferably, the ply gauge between the bead wire and the bead base is 0.7 or less of the ply gauge of the gooseneck portion.

More preferably, in the flat pneumatic bias tire for a wheel loader described above, the ply gauge between the bead wire and the bead base includes: a. A gauge of the inner ply bundle between the inner bead wire and the bead base / the inner bead wire and the bead base; G _IW , the number of plies (ratio) of the inner ply bundle between the _gaps , and b. The gauge of the outer ply bundle between the outer bead wire and the bead base / the number of plies (ratio) of the outer ply bundle between the outer bead wire and the bead base, G _OW , and, on the other hand, for the ply gauge of the gooseneck, c.
G _{IN is} the gauge of the inner ply bundle at the gooseneck portion / the number of plies (ratio) of the inner ply bundle at the gooseneck portion, and d is the gauge of the outer ply bundle at the gooseneck portion / G is the ply number (ratio) of the outer ply bundle at the gooseneck portion. _ON , G _IW ≦ 0.7G _{IN for the} inner ply and G _{OW for} the outer ply
≦ 0.7G _ON . In this case, the G _IW and G _OW particularly preferably in the relationship of _{0.9G OW ≦ G IW ≦ 1.5G OW} .

(Operation) The tire transmits a load or other force from a vehicle to a road surface or vice versa by a flow from a vehicle → a rim → a tire (bead base → bead wire → ply cord → tread) → a road surface.

Among these, the mode of transmission of the force between the bead wire and the ply cord is most related to the durability of the carcass, particularly the carcass in the bead portion.

The present application effectively improves the durability of the carcass, especially the carcass in the bead portion, by effectively using all the ply cords in the carcass and efficiently transmitting the force to and from the bead wire by using as few members as possible. Its purpose is to achieve.

As the means, the above-mentioned configuration is adopted.More specifically, by narrowing the gauge between the bead wire and the bead base, within the carcass ply wound around the same bead wire, the inner carcass ply and the outer carcass ply are separated. By reducing the difference in peripheries, the cord tension borne by the carcass ply when filling with internal pressure can be made uniform, and the rigidity of the bead portion can be increased to reduce the deformation under load, thereby suppressing the cord distortion of the bead portion. This is to improve the fatigue resistance of the carcass ply in the part.

Furthermore, in each ply bundle of the inner ply and the outer ply, the ply gauge around the bead wire is defined in order to improve the efficiency of the force transmission with the bead wire. The ratio of the ply gauge between the bead wire and the bead base between the inner ply and the outer ply in order to improve the efficiency of the transmission of force as a whole carcass by balancing both the transmission of force in the outer ply It is.

Reducing the ply gauge between the bead wire and the bead base from the ply gauge of the gooseneck part, that is, making the ply gauge between the bead wire and the bead base smaller than the ply gauge of the gooseneck part, reduces the periphery difference around the bead, The cord tension at the time of filling the tire pressure is made uniform, the rigidity is increased, and therefore deformation under load is small, which means that the cord distortion at the bead portion is small and the fatigue failure of the bead portion is reduced. is there.

(1) Action of ply gauge around bead wire The ply bundle winds up the bead wire at the bead portion, but its curvature is considerably large. Therefore, if there is too much room in the gauge of the ply bundle between the bead bases of the bead wires, a difference occurs between the peripheries of each ply cord, and regarding the transmission of the force between the ply bundle and the bead wire,
A bias occurs between the ply cords, and the spring constant, that is, the rigidity of the bead portion is reduced in the entire ply bundle.

Therefore, in order to effectively utilize all the ply cords in the ply bundle and to increase the spring constant, that is, the rigidity of the entire ply bundle, the ply gauge between the bead wire and the bead base is wound up, for example, the ply gauge of the gooseneck portion. It is desirable to squeeze it thinner than the ply gauge, and the ply gauge between the bead wire and the bead base is 0.7 or less of the ply gauge of the gooseneck part, more specifically, G _IW ≦ 0.7G _{IN for the} inner ply and G _{OW for} the outer ply.
It is better to be ≤0.7G _ON .

(2) Action of the ply gauge below the bead wire of the inner and the outer When the number of the bead bundles is two, the inner ply bundle and the outer ply bundle in the bead portion are well balanced with the force between the ply cords above the bead wire and the bead. If it does not work as a transmission member, the load is biased to one of the ply bundles, and the spring constant (rigidity) of the bead portion as a whole carcass also decreases.

Therefore, in order to effectively use the entire ply bundle in the carcass and increase the spring constant of the entire bead portion carcass,
It is desirable to set the ratio of the degree of squeezing of the ply gauge of both the inner ply and the outer ply within a certain range, and the range is 0.9 G _OW ≦ G _IW ≦ 1.5 G _OW .

If G _IW is smaller than 0.9 G _OW , the force is biased to the inner ply bundle, and if G _IW is larger than 1.5 G _OW , the force is biased to the outer ply bundle. Become.

(Examples) The present invention will be described in detail based on examples.

FIG. 1 is a radial sectional view of a bead portion of a pneumatic bias tire for a wheel loader of the present invention. The pneumatic bias tire for a wheel loader of the present invention is a tire having two bead bundles, 1 is an inner bead wire, 2 is an outer bead wire, 3 is an inner ply bundle, and 4 is an outer ply bundle. 5 is a ply gauge between the inner bead wire 1 and the bead base 9, and 6 is a ply gauge between the outer bead wire 2 and the bead base.
Ply gauge. Reference numeral 10 denotes a gooseneck portion, 7 denotes an inner ply bundle gauge at this portion, and 8 denotes an outer ply bundle gauge at this portion.

Example 1 The tire used was ORS 20.5-25 12PR (L3 class), and nylon (1890d / 2) was used as a carcass.

The number of plies is six, the inner ply is wound up two, the outer ply is wound up two, and the ply is not wound.

Gauge between bead wire and bead base is 1mm on inner bead wire side, 0.8mm on outer bead wire side
It is. The ply bundle gauge at the gooseneck is 2 mm on the inner bead wire side and 2 mm on the outer bead wire side.
mm.

G _IW , G _OW , G _IN , and G _ON are 0.5, 0.4, 1.0, and 1.0, respectively. G _IN : G _IW = 1: 0.5, G _ON : G _OW = 1: 0.4, G _IW : G _OW = 1.25:
Is one.

The tire used as a comparative example was the same as that in Example 1 except that the gauge between the bead wire and the bead base was 2 mm on both the inner bead wire side and the outer bead wire side.

Example 2 The tire used was ORS 23.5-25 16PR (L3 class), and nylon (1890d / 2) was used as a carcass.

The condition is that the number of plies is 10, the winding of the inner ply is 4, the winding of the outer ply is 4, and the ply is not wound.

The gauge between the bead wire and the bead base is 2.3 mm on the inner bead wire side and 2.3 mm on the outer bead wire side.
mm. The ply bundle gauge of the gooseneck is 4.5 mm on the inner bead wire side and 4.5 mm on the outer bead wire side.

G _IW , G _OW , G _IN , and G _ON are 0.6, 0.6, 1.1, and 1.1, respectively. G _IN : G _IW ≒ 1: 0.5, G _ON : G _OW ≒ 1: 0.5, G _IW : G _OW = 1: 1.

The tire used as a comparative example had a gauge between the bead wire and the bead base of 4.5 m on the inner bead wire side.
Example 2 except that m was 4.5 mm on the outer bead wire side
And the same.

Example 3 The tire used was ORS 26.5-2520PR (L3 class), and nylon (1890d / 2) was used as a carcass.

The condition is that the number of plies is 12, the inner ply is wound up to 6, the outer ply is wound up to 4, and the ply is not rolled up to 2.

The gauge between the bead wire and the bead base is 5.5 mm on the inner bead wire side and 2.5 mm on the outer bead wire side.
mm. The ply bundle gauge of the gooseneck is 7.5 mm on the inner bead wire side and 5.0 mm on the outer bead wire side.

G _IW , G _OW , G _IN , and G _ON are 0.9, 0.6, 1.3, and 1.3, respectively. G _IN : G _IW ≒ 1: 0.7, G _ON : G _OW ≒ 1: 0.5, G _IW : G _OW = 1.5: 1
It is.

Incidentally, the tire used as a comparative example, the gauge between the bead wire and the bead base is 7.5m on the inner bead wire side
Example 3 except that m was 5.0 mm on the outer bead wire side.
And the same.

The test of the obtained tire was performed by an indoor drum test. Test conditions are air pressure: JIS standard 3-4 atm, load: JIS
Standard Maximum load 10-20 tons, running conditions: around 10 days
The speed was 8 km / hrs.

(Effects of the Invention) If the effects of the present invention are described based on the above-described examples, the reduction rate of the remaining strength of the ply cord at the bead portion after traveling for a certain time is 1/2 to that of the tire of the comparative example Reduced to 1/4. This indicates that the tire according to the present invention has an improved fatigue failure life at the bead portion.

[Brief description of the drawings]

FIG. 1 is a radial sectional view of a bead portion of a pneumatic bias tire for a wheel loader of the present invention. 1 ... inner bead wire 2 ... outer bead wire 3 ... inner ply bundle 4 ... outer ply bundle 5 ... ply gauge between inner bead wire and inner bead base 6 ... between outer bead wire and outer bead base Ply gauge 7: Inner ply bundle gauge at gooseneck 8: Outer ply bundle gauge at gooseneck 9: Bead base 10: Gooseneck

Claims (4)

(57) [Claims] A real ply having an angle of 30 to 40 degrees with respect to the tire circumferential direction has 6 to 14 carcass, and the carcass extends from one bead portion to another bead portion, and the bead portion is A flat tire for a wheel loader having excellent durability, wherein a ply gauge between a bead wire and a bead base is smaller than a ply gauge at a gooseneck portion in a bias tire for a wheel loader having two bead bundles and an aspect ratio of 0.8 to 0.85. Pneumatic bias tire. 2. The flat pneumatic bias tire for a wheel loader according to claim 1, wherein the ply gauge between the bead wire and the bead base is 0.7 or less of the ply gauge of the gooseneck portion. 3. The ply gauge between the bead wire and the bead base: a. The gauge of the inner ply bundle between the inner bead wire and the bead base / the number of plies (ratio) of the inner ply bundle between the inner bead wire and the bead base.
G _IW , b. Gauge of outer ply bundle between outer bead wire and bead base / Number of plies of outer ply bundle between outer bead wire and bead base (ratio)
_{Is defined} as G _OW , and the ply gauge at the gooseneck portion is: c. The gauge of the inner ply bundle at the gooseneck portion /
The number of plies (ratio) of the inner ply bundle at the gooseneck is G _IN , d. The gauge of the outer ply bundle at the gooseneck is
The ply number (ratio) of the outer ply bundle at the gooseneck portion is G _ON , wherein G _IW ≦ 0.7 G _{IN for the} inner ply and G _OW ≦ 0.7 G _ON for the outer ply.
A flat pneumatic bias tire for a wheel loader as described in the above. 4. The method according to claim 1, wherein said G _IW and said G _OW are 0.9 G _OW ≦ G _IW ≦ 1.5 G
_4. The flat pneumatic bias tire for a wheel loader according to claim 3, wherein the tire has an _OW relationship.