A sprocket is a wheel with recessed teeth for meshing with a block of precisely spaced links or cables. Sprocket is widely used in chemical industry, textile machinery, escalator, wood processing, three-dimensional parking garage, agricultural machinery, food processing, instrumentation, oil and other industries of mechanical transmission.
The causes of serious wear of sprocket chain socket are as follows:
(1) the greater the adhesive wear load, the higher the surface temperature, and the more serious the adhesive phenomenon. For metal materials with a certain hardness, wear tests under different pressures have obtained a relationship curve between wear rate and pressure. When the pressure reaches more than 1/3 of the material hardness, severe wear will occur. According to the stress distribution diagram, the maximum stress contact point is the maximum pressure point, and its value is 884.4mpa. Because the quenching hardness of the chain socket is HRC48~52, the corresponding hardness value is 4800MPa. Therefore, the pressure is much less than a third of the material hardness, so adhesive wear is not the main form of sprocket wear.
(2) contact fatigue wear
The friction pair of sprocket wheel and chain is the alternating contact stress, which is easy to form fatigue pitting on its friction surface. The index to judge the metal contact fatigue strength is the contact fatigue limit, that is, the maximum stress without pitting under a certain number of stress cycles. After surface quenching, contact fatigue limit of 40Cr 0H=HRC17 +200, and 0H=1016MPa was calculated. According to the stress distribution diagram, the maximum stress value of sprocket socket is 884.4mpa. Its value is very close to the allowable contact fatigue limit on the sprocket surface, and it is easy to cause pitting failure at the maximum stress. However, due to the poor lubrication conditions of sprocket wheel and chain, pitting corrosion has not formed too late, has caused wear, then the main form of damage is wear rather than pitting. Contact fatigue wear is the main form of sprocket wear, which basically determines the service life of sprocket.
(3) abrasive wear
Due to the inevitable contact between the chain and the pulverized coal, there is a little pulverized coal on the chain, which is brought to the contact of the sprocket chain socket. The pulverized coal contains a little pointed hard sand, which will cause the material on the surface of the sprocket to fall off in the friction process, which is abrasive wear. Abrasive wear and friction material hardness, abrasive hardness. From the influence diagram of abrasive hardness on wear, it can be seen that when the hardness of abrasive is close to that of friction material, it will cause friction material to wear at high speed, because coal powder is mixed with a little pointed hard sand, which is also one of the main reasons for accelerated sprocket wear.