The reasons for serious wear of sprocket wheel chain socket are as follows:

(1) The larger the adhesive wear load, the higher the surface temperature, the more serious the adhesive phenomenon. For a certain hardness of metal materials, the wear rate and pressure curves are obtained by wear tests under different pressures. When the pressure reaches more than 1 / 3 of the material hardness, serious wear will occur. According to the stress distribution diagram, it can be seen that the stress contact point is the place with large pressure, and its value is 884.4 MPa. As the quenching hardness of the chain socket is hrc48-52, the corresponding hardness value is 4800mpa. Therefore, the pressure is far less than 1 / 3 of the material hardness, so adhesive wear is not the main form of sprocket wheel wear.

(2) Contact fatigue wear

The friction pair of sprocket wheel and chain is an 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 large stress without pitting under a certain number of stress cycles. The contact fatigue limit of 40Cr after surface quenching is σ 0h = hrc17 + 200, which is calculated to be σ 0h = 1016mpa. According to the stress distribution diagram, the large stress value of sprocket wheel chain socket is 884.4 MPa. Its value is very close to the allowable contact fatigue limit of the sprocket wheel surface, and it is easy to cause pitting failure at large stress. However, due to the poor lubrication conditions between the sprocket wheel and the chain, pitting has not been formed yet, which has caused wear. At this time, the main form of damage is wear rather than pitting. Contact fatigue wear is the main form of sprocket wheel wear, which basically determines the service life of sprocket wheel.

(3) Abrasive wear

Due to the inevitable contact between the chain and the pulverized coal, there is a little pulverized coal stuck on it, which is taken to the contact point of the sprocket wheel chain socket. The pulverized coal contains a little sharp and hard sand, which will cause the fall off of the surface material of the sprocket wheel during the friction process, which is abrasive wear. Abrasive wear is related to hardness of friction material and abrasive. It can be seen from the influence diagram of abrasive hardness on wear that when the hardness of abrasive is close to that of friction material, high-speed wear of friction material will be caused, because there is a little hard sand mixed with pulverized coal, which is also one of the main reasons for accelerating the wear of sprocket wheel