The reasons for the serious wear of the 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 contact point of high stress is the place with high 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 hardness of the material, so adhesive wear is not the main form of sprocket wear.

(2) Contact fatigue wear

It is easy to form fatigue pitting on the friction surface of sprocket and chain. 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 the socket is 884.4 MPa. Its value is close to the allowable contact fatigue limit of the spruck surface, and it is easy to cause pitting failure at high stress. However, due to the poor lubrication conditions between the sprocket and the chain, pitting has not been formed, 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 wear, which basically determines the service life of sprocket.

(3) Abrasive wear

Because the chain inevitably contacts with the pulverized coal, there is a little pulverized coal stuck on it, which is taken to the contact of the sprocket chain socket. The pulverized coal contains a little sharp and hard sand, which will cause the surface material of the sprocket to fall off 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 the hardness 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 to accelerate the wear of sprocket.