Tire tread pattern has a great influence on the cooling performance of the tire tread. A good pattern cooling effect can ensure that the tire runs at a low temperature and improves the durability and service life of the tire. This work is based on the Fourier heat conduction equation, indoor machine tool test and actual claims tire analysis, and discusses the heat dissipation performance of tread pattern of all-steel radial truck tires.
1 Heat Dissipation of Tire Patterns Tire tread patterns are roughly divided into vertical and horizontal ribs and blocks.
1. 1 basic equation of heat conduction Fourier law basic equation of heat conduction Fourier law.
The following assumptions are made: (1) The internal thermal conductivity inside the air is the same; (2) The temperature gradients at the rubber and air interfaces are the same.
According to the above assumptions, the size of tread surface area determines the heat dissipation capacity of the pattern. In general, the area of ​​the block pattern, the vertical ribs, and the horizontal ribs successively decreases, so the heat dissipation capacity decreases in turn. Actually, the temperature gradients at different positions of the tread pattern are different, the temperature gradient at the bottom of the groove is larger, and the temperature gradient of the block surface is smaller. Therefore, it can be said that the heat dissipation ability of the tread pattern increases with the increase of the surface area of ​​the groove bottom.
1. 2 Indoor Test and Actual Claims Tire Statistics A large number of indoor mileage test data statistics show that the cooling capacity of the tread pattern decreases from the block pattern, the vertical stripe pattern to the horizontal strip pattern in turn. Different types and depths of the pattern, the fatigue strength and the degree of flexion are also different, resulting in different heat production speed rubber, and heat production and tire temperature has a close relationship.
The statistical analysis of tires in our company's actual claims shows that tires with block patterns and longitudinal strips have significantly lower tire shoulder and tread delamination quality defects than horizontal ribbed tires due to heat generation, which is in line with the results of indoor tests.
From the basic equations of heat conduction theory, indoor tests and actual claims tire statistics analysis, it can be concluded that the general rule of thumb is that the heat dissipation performance of block patterns is better than that of vertical and horizontal strip patterns.
2 Optimized design 2.1. Increased circulation of air in the tread pattern The heat dissipation effect of the tire is mainly through the contact between the tire surface and the air, and the use of the temperature difference between rubber and air to dissipate the heat into the air. Increasing the circulation of air in the tread pattern actually maintains the temperature difference between the rubber and the air, allowing good heat flow between the two.
Figures 1 and 2 show the block patterns and transverse rib patterns that are commonly used in the current market. During the running of the tire, the air flow between the block patterns is good, the heat exchange can be fully performed, and the heat dissipation effect is good; the horizontal strip pattern is blocked by the horizontal blocks, the air cannot flow between the blocks, and the heat cannot be fully performed. Exchange, poor heat dissipation. Market surveys have shown that block tyres have significantly fewer shoulder delamination problems than transverse ribbed tyres.
At present, the XDE2 pattern on the market is very typical, such as the Michelin pattern. The angle design on the block fully takes into account the circulation of air between the blocks, thus improving the overall pattern of heat dissipation.
2. 2 Decrease the groove groove angle. According to the Fourier equation, the cross-sectional area of ​​the groove is known.
The smaller the pattern groove angle, the better the heat dissipation effect at the bottom of the groove. On the other hand, the pattern grooves increase the surface area of ​​the tire tread, increase the temperature gradient between the rubber and the air, and are more conducive to the heat dissipation of the crown of the tire.
Therefore, reducing the groove angle properly will help the tire heat dissipation.
2. 3 The other belt ends are the parts where the elastic modulus of the steel wire and the rubber material are greatly different. When the tire is running, the deformation of the shoulders of the tire is large and the heat generation is faster. Therefore, the heat dissipation at the shoulder is particularly important. The following optimal design of the shoulder pattern can improve the ability of the tire shoulder to dissipate heat.
(1) shoulder shoulder mouth.
(2) Shoulder plus heat sink, block plus heat sink, etc.
(3) Add a cooling block at the bottom of the groove.
According to the above analysis, the design of the 10.00R20 and 11.00R20 specifications of the BTR tire tread pattern is optimized. A row of heat sink blocks are added to the main groove on both sides of the shoulder to optimize the design of the tread pattern before and after the tread pattern. In the market, tire shoulder delamination problems have been reduced by about 5%, while creating good economic benefits.
3 Conclusion Although the tire tread pattern is simple, but its mechanism of action is very complex, and many mechanisms are still unclear, tread pattern design still lacks effective theoretical guidance. Optimizing the design of the tread pattern enables the tire to have a good heat dissipating effect during running, thereby improving the durability of the tire. There are various methods and methods for improving the heat dissipation performance of the tread pattern, but attention should be paid to its overall performance while considering the effect of pattern heat dissipation.
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