JPS6410362B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a bias tire for construction vehicles, and particularly to a construction vehicle having a metal cord layer on the outer periphery of a carcass having a bias structure, and further disposing an organic fiber cord layer on the outer periphery of the metal cord layer. The present invention relates to improvements to bias tires for use in automobiles. [Prior Art] In conventional bias tires for construction vehicles, the metal cord layer and the lower layer of treaded rubber are in direct contact with each other at the tire crown, or there is an adhesive effect in the middle part.
It is constructed by arranging a rubber layer with different properties from tread rubber for reasons such as buffering effect and internal heat generation effect, but since there is a large difference in rigidity between the metal cord layer and the rubber layer including tread rubber, In bias tires used under harsh conditions such as on high-load construction vehicles, the rubber of the metal cord layer breaks or the cord occurs at the thinnest rubber wall where the tire contacts the road surface, that is, inside the center of the crown. The drawback was that adhesive failure with the rubber grew and delamination (separation) occurred. Recently, a method has been proposed in which an organic fiber cord layer is disposed on the top surface of the metal cord layer so as to cover it, thereby preventing the above-mentioned drawbacks, that is, separation caused by the difference in rigidity and damage caused by cuts. ing. (Tokuko Showa 53-
(Refer to Publication No. 15241) However, in the above-mentioned method, since the metal cord layer is wrapped in the organic fiber cord layer from the upper and lower surfaces, the expansion/contraction, expansion rate, etc. of the two layers are different.
During tire manufacturing, when the vulcanization process is finished and the temperature inside the tire drops, a small space is created at both ends of the metal cord, which grows during driving and can cause internal breakage, separation, and other failures. The current situation is that there are still problems, such as the cause of this. [Object of the Invention] The present invention was developed as a result of experiments and studies to solve the above-mentioned problems. Therefore, an object of the present invention is to improve the heat resistance during running by adjusting the arrangement width of the organic fiber cord layer arranged around the outer periphery of the metal cord layer with respect to the width of the metal cord layer and the width of the tread crown. An object of the present invention is to provide an excellent bias tire for construction vehicles that can reliably prevent delamination inside the tire without causing damage and can withstand long-term use under harsh conditions. [Structure of the Invention] That is, the present invention provides a carcass 2 consisting of at least two left and right pairs of bead bundles 1, a plurality of intersecting organic fiber cords 2a wound around each bead bundle 1, and an outer periphery of the carcass 2. In a bias tire for a construction vehicle, the width 4a of the organic fiber cord layer 4 is made of The gist of this invention is a bias tire for a construction vehicle, characterized in that the arrangement width 3a of the metal cord layer 3 is not exceeded and the width is 80% or less of the tread crown width 5a. [Embodiments of the Invention] The present invention will be specifically described below using Examples with reference to the drawings. As shown in FIG. 1, a bias tire for a construction vehicle according to an embodiment of the present invention is made of a pair of left and right bead bundles 1 and a plurality of layers of mutually intersecting organic fiber cords 2a wound around each bead bundle 1. a carcass 2, a metal cord layer 3 disposed around the outer periphery of the carcass 2, and an organic fiber cord layer 4 disposed around the outer periphery of the metal cord layer 3.
In particular, in the present invention,
The width 4a of the organic fiber cord layer 4 is set within a range that does not exceed the arrangement width 3a of the metal cord layer 3, and is set to be 80% or less of the tread crown width 5a. Therefore, it is possible to obtain an excellent bias tire for construction vehicles that reliably prevents delamination inside the tire without impairing heat resistance during running and can withstand long-term use under harsh conditions. This will be explained in detail below along with experimental results. Figure 2 shows one example of a prototype kazukazu produced for comparative evaluation with the present invention, in which the arrangement width 4a of the organic fiber cord layer 4 was made wider than 80% of the crown width 5a. In the example of bias tires, 6
6a indicates the shoulder portion of the tire, 6a indicates the maximum cross-sectional thickness of the shoulder portion, and 6b indicates a point on the metal cord layer 3 on the line of the maximum cross-sectional thickness 6a of the shoulder portion.
This type of bias tire is of course effective in terms of separation resistance due to the difference in rigidity between the metal cord and the rubber, but the shoulder section 6a, where the internal heat generation of the tire that occurs when the vehicle is running, is usually the highest. If the thickness increases too much, failures such as internal destruction due to heat generation are likely to occur, and the conventional functions of the tire will be impaired, making it impossible to expect an improvement in overall durability. Figure 3 shows an example of a prototype tire in which the arrangement width 4a of the organic fiber cord layer 4 is further widened to sufficiently cover the entire arrangement width 3a of the metal cord layer 3. As disclosed in the publication ``Highly Durable Pneumatic Tires for Construction Vehicles,'' this type of tire is somewhat effective in terms of separation resistance due to rigidity differences and damage due to cuts, but it is Carcass 2 consisting of organic fiber cord layer 2a and organic fiber cord layer 4
Since the metal cord layer 3 is wrapped between the As shown in FIG. 3b, minute spaces 7 are formed at both ends, which grow during running and cause failures such as internal destruction and separation. Furthermore, if the arrangement width 3a of the metal cord layer 3 is wider than 6a, the width 4a of the organic fiber cord layer 4 will naturally also become wider, so internal destruction due to heat as explained in FIG. 2 will occur, resulting in It is difficult to improve overall tire durability. [Experimental Example] As described above in the present invention, the width 4a of the organic fiber cord layer 4 is the same as the tread crown width 5a.
An example of an experiment conducted to confirm the effect of setting it to 80% or less will be explained. The specifications of the tires used in this experiment and the experimental conditions are as follows. Tire of the present invention...Arrangement width 4 of organic fiber cord layer 4
a is 80% of the treaded crown width 5a.
(Indicated by A in FIG. 4) Conventional tire: Organic fiber cord layer 4 is not arranged. (Indicated by B in Fig. 4) Comparative tire 1...The arrangement width 4a of the organic fiber cord layer 4 is 90% of the tread crown width 5a.
%. (Indicated by C in Fig. 4) Comparative tire 2... The arrangement width 4a of the organic fiber cord layer 4 is 120 mm of the tread crown width 5a.
%. (Indicated by D in Figure 4) Tire size...12.00-20-16PR (bias tire for construction vehicles) Rim...8.50V x 20IR Air pressure...6.50Kg/cm ² Experimental conditions...Temperature was 38℃ Indoor diameter 1700mm
Immediately after running the drum continuously for 90 minutes under the conditions shown in Table 1 below, the temperature near the metal cord layer 3 6b having the maximum cross-sectional thickness 6a in the shoulder portion 6 was measured.

〔Effect of the invention〕

As described above, in a bias tire for a construction vehicle having a carcass 2 having a bias structure, the width 4a of the organic fiber cord layer 4 disposed on the outer periphery of the metal cord layer 3 is Since the width of the tread crown width 5a is set within a range not exceeding 80% of the tread crown width 5a, the following effects can be achieved. That is, (a) since the width 4a of the organic fiber cord layer 4 is arranged within a range that does not exceed the arrangement width 3a of the metal cord layer 3, the internal temperature of the tire decreases after the vulcanization process is completed during tire manufacturing. At this time, unlike in the case where the organic fiber cord layer 4 is arranged beyond the arrangement width 3a of the metal cord layer 3 described above, the space 7 is not generated at both ends of the metal cord layer 3.
As a result, failures such as internal destruction and separation caused by the growth of the space 7 can be reliably prevented during running. (b) Since the arrangement width 4a of the organic fiber cord layer 4 is set to 80% or less of the tread crown width 5a, as is clear from the above-mentioned experimental results, the tire of the present invention has organic fibers on the outer periphery of the metal cord 3. Despite the arrangement of the cord layer 4, heat resistance during running is not impaired. As a result, due to the temperature rise inside the tire during running, the organic fiber cords 2a constituting the carcass 2 near the maximum cross-sectional thickness 6a in the shoulder portion 6 and the organic fiber cords constituting the organic fiber cord layer 4 deteriorate. Reliably prevents separation between layers such as between the rubber layer constituting the tread and the organic fiber cord layer 4 due to melting or reversion (reversion phenomenon) of the rubber in this area. be able to. Therefore, the present invention makes it possible to obtain an excellent bias tire for construction vehicles that reliably prevents delamination inside the tire without impairing heat resistance during running, and can withstand long-term use under harsh conditions. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a bias tire for construction vehicles according to an embodiment of the present invention, and FIG. 2 is an experimentally produced tire with a wider arrangement width of the organic fiber cord layer for comparison with the tire of the present invention. Figure 3a is a cross-sectional view of the ivy tire. Figure 3a is a cross-sectional view of a tire experimentally made with the organic fiber cord layer arranged wider and wrapped around the metal cord layer. Figure 3b is Figure 3b. B of a
FIG. 4 is an enlarged view of the portion shown in FIG. 4, which compares the internal temperature of the tires when the tires shown in FIG. 1 and those shown in FIG. 2 were prototyped and subjected to an indoor rotation test. 1... Bead bundle, 2... Carcass, 2a... Organic fiber cord layer constituting the carcass, 3... Metal cord layer, 3a... Width of metal cord layer, 4... Organic fiber cord layer, 4a... Width of organic fiber cord layer, 5... Tire tread crown portion, 5a...
Treaded crown width.

Claims (1)

[Claims] 1 A carcass 2 consisting of at least two left and right pairs of bead bundles 1, a plurality of layers of mutually intersecting organic fiber cords 2a wound around each bead bundle 1, and a metal cord layer arranged around the outer periphery of the carcass 2. 3 and an organic fiber cord layer 4 arranged around the outer periphery of the metal cord layer 3, the width 4a of the organic fiber cord layer 4 is defined as the arrangement width of the metal cord layer 3. A bias tire for construction vehicles characterized by having a tread crown width not exceeding 3a and 80% or less of the tread crown width 5a.