Nowadays, underground scrapers are used in large quantities. However, the operating cost, production efficiency and loading capacity of the scraper depend largely on the performance and maintenance of the tires. Therefore, pneumatic tires with high maneuverability and passability, excellent traction adhesion performance and shock resistance have become indispensable accessories.
1. Correct selection
Each type of scraper stipulates the specifications, types, layers, patterns, and presence or absence of inner tires of the tires used. When choosing a tire, you must select a tire with some outstanding performance according to the specific conditions of the working environment, and comprehensively consider various influencing factors such as road conditions, climate, load, speed, and working conditions. If it is used for long-distance transportation, it needs good heat resistance and watery areas. It needs good water resistance. At the same time, certain characteristics of the tires are mutually restrictive and must be considered comprehensively.
When choosing a tire, you should also consider its walking quality, traction, off-road capability and the life of the tread. Inclined cord tires have very thick sidewalls, which have good puncture resistance and lateral stability. They are usually used under conditions of high impact load and strong corrosion, but this type of tire generates heat quickly and is not suitable for long-distance high-speed operation; radial tires The calorific value is small, the temperature rise of the tire is relatively low during high-speed operation or long-distance operation, and it has good elasticity and low rolling resistance. This type of tire should be selected when the scraper works in milky soil.
Scraper tires are characterized by high load capacity, high traction, and harsh service conditions. They require a large ground contact area for the tires to provide a low ground contact pressure. The tread is resistant to wear and puncture, and the heat generated in each part is small. The width of the tire section, the high curvature of the running surface, the position of the horizontal axis of the section, the shoulder arc, the tread degree, and the crown cord angle all have an impact on these properties, which in turn affects the service life of the tire. The width of the tire's cross-section determines the tire's ground contact area and the pressure of the ground contact, which has an important impact on the tire's wear resistance and driving stability. If the width of the section is narrow, the grounding area is small, and the pressure at the grounding position is high, the tread is easy to wear, which shortens the life of the tire. The arc of the running surface affects the width of the tire contacting the ground and the unit pressure distribution of each point on the contact surface when the tire is inflated and rolled under load. If the arc is too large, the width of the tire contacting the ground is small, the stress at the contact point is uneven, and the tread is easy to wear; if the arc is too low, the shoulders will be too thick, which will cause excessive heat generation and poor heat dissipation of the tire, causing the tire to fall off Early damage occurs at the shoulder, shortening the service life of the tire. The position of the horizontal axis of the section is the part where the tire deforms and deflects the most. If the H1 / H2 value is too large, it will cause the shoulder of the tire to generate heat and cause early damage to the tire. The shoulder area is the thickest part of the tire. If the shoulder radius is small, the shoulder thickness is thick, the heat is large, and the heat dissipation is difficult, it is easy to cause the shoulder to blister. The shoulder is easily damaged by the driving environment and the tire is prematurely damaged. The thickness of the tread rubber has a double effect on the tire. The thick tread rubber can improve the wear resistance and puncture resistance of the tire on the one hand, and increase the difficulty of heat generation and heat dissipation of the tread on the other hand. The crown cord angle is an important index to control the deformability of the carcass and the load bearing capacity of the tire after inflation. If the angle design is improper, the carcass is easily deformed and the load-bearing capacity is reduced, which shortens the life of the tire.
The same scraper should choose the same type of tires, especially the tires used on the same shaft must be the same size, type and level. Since the number of tire specifications is that the nominal size is not the same as the actual size, the actual size of tires with the same nominal size may be different, which may cause different rolling radii. When the rolling radii of tires on the same drive axle are not equal, the rolling radius is small The speed of the tire is faster than the rolling radius, so the drive axle is subjected to the concentrated stress caused by the tire sliding; the four-wheel drive scraper, the stress caused by the different rolling radius of the tire will also be amplified by the transmission chain.
The specifications of the tire and the wheel rim must be matched. If the width of the wheel rim is too small, the curvature of the tire tread will be large, which will aggravate the wear of the tire. If the width of the wheel rim is too large, the tread will be shouldered on the ground and the center will be recessed. The wear is severely uneven. Therefore, each type of tire has a permitted rim. Combined with the actual situation of the mine yard in our mine, we choose ultra-thick radial tires, which have smooth and smooth treads and large widths. Therefore, the grounding area is increased, and the grounding pressure is evenly distributed, with good cutting resistance and wear resistance. Alleviating the short service life of tires used in mining equipment is a very prominent problem.
2. Appropriate inflation pressure
Inflation pressure has a great influence on tire life. Too high or too low inflation pressure will cause the tire to fail prematurely. Maintaining normal tire pressure can reduce tire consumption.
If the air pressure of the tire is too high, the cord will have greater stress regardless of whether it is overloaded or not, reducing the ability to resist bursting when impacted. The reduced ground contact area of the tire can increase the wear of the tread, which is not conducive to the maintenance of the tire and its side When the rigidity of the wall becomes larger, it is more likely to be stabbed, cut, and burst, and the off-road ability and traction ability are also reduced, which is easy to make the tire slip.
When the tire pressure is insufficient, the tire deforms greatly, increasing the internal stress and increasing the temperature, thereby accelerating the aging of the rubber and the fatigue of the cord. Eventually, the cord is broken, the cord is delaminated, and the tread is broken, which will cause the same The rolling radius of the tires with different specifications leads to the early damage of the tires. When the tire pressure is only normal, the life of the tire will decrease. When the tire pressure is only normal, the life of the tire will decrease. When the machine is driving on rough roads, if the inflation pressure is slightly lower than the normal pressure, it can alleviate the impact load and improve the stress concentration, but can increase the service life of the tire.
3. Prevent overspeed and overload
Each type of scraper has a specified maximum speed and average speed. When the machine is speeding, the temperature of the tire increases and the ply is separated, which will accelerate the wear and tear of the tire and shorten the life of the tire. The figure shows the relationship between vehicle speed and tire life. When the scraper is running, the dynamic load on the tire is very large. Even when driving at a medium speed on a flat road, the dynamic load is twice the static load. The dynamic load increases with the unevenness of the road surface, the speed of the machine and the rigidity of the tire. When driving on a flat road surface, the dynamic load is almost proportional to the square of the vehicle speed, so the load of the scraper must be less than its maximum rating The load will be twisted and heated when the tire is overloaded. If the temperature is too high, the tires separated from the ply can be extremely deformed, which can cause the tires to wear and tear quickly.
4. Drive correctly
Even when driving on a flat road, if the driver improperly operates, the tire will be damaged or even scrapped.
The scraper should start with a low gear, reduce the speed when turning, and avoid excessive braking (the heat generated by emergency braking can make the tread rubber soft and heated, and the tread can be worn away by one emergency braking 0.9mm); when the machine is walking, the road surface with oil should be bypassed; the greater the slope of the driving road surface, the greater the impact on the life of the tire, so the shovel should be driven as little as possible when driving.
In addition, the training of drivers should be strengthened, including driving methods, safety technology and technical maintenance.
5. Maintenance and repair of tires
Pneumatic tires can not be close to places where the temperature is too high, nor can we perform welding operations on the pneumatic tires. Because the installation position of each tire on the machine and the load it bears are different, the wear of each tire is different, so it must be replaced regularly. The performance of the braking system must be maintained to prevent the wheels from locking to avoid rapid wear of the tires. When installing the tires, the nuts on the tires should be tightened according to the specified tightening torque.
6. Ensure that the road is in good condition
The condition of the road is also a factor that affects the life of the tires. Therefore, the road must be effectively maintained before the operation to avoid spilling materials on the road or slopes in sharp turns. Clear obstacles on the road in a timely manner and keep the road clear. . If the road is damaged due to long use time or overload or low road quality, the road surface will become uneven, which will increase the impact force of the tire and increase the probability of tire failure due to impact, shearing and cutting. In order to avoid the overturning accident of the machine during the sharp turn, the road surface should form a horizontal slope, and the steep uphill should be excluded. As long as the above aspects are completed, the service life of the tire can be effectively extended and the economic benefit can be improved.
Scraper tires have harsh service conditions, high performance requirements, complicated manufacturing processes, expensive prices, and many factors that affect service life. Only by properly and comprehensively analyzing the factors that affect the service life of the tires and using and managing the tires correctly can we fundamentally increase the service life of the tires.
