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The causes of serious wear of sprocket socket are as follows

Writer: admin Time:2021-11-19 10:10 Browse:

(1) The greater the adhesion wear load, the higher the surface temperature, and the more serious the adhesion phenomenon. For metal materials with certain hardness, wear tests are carried out under different pressures, and the relationship between wear rate and pressure is obtained. When the pressure reaches more than 1 / 3 of the hardness of the material, serious wear will occur. According to the stress distribution diagram, the maximum stress contact point is the maximum pressure, and its value is 884.4 MPa. Because the quenching hardness at 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 wear.
 
(2) Contact fatigue wear
 
The friction pair between sprocket and chain is an alternating contact stress, which is easy to form fatigue pitting corrosion 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. Contact fatigue limit of 40Cr after surface quenching σ 0h = hrc17 + 200, calculated σ 0H=1016MPa。 According to the stress distribution diagram, the maximum stress value of sprocket chain socket is 884.4 MPa. 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 and chain, pitting corrosion has not been formed, which has caused wear. At this time, the main damage form is wear rather than pitting corrosion. 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 pulverized coal, a little pulverized coal is stuck on it and brought to the contact of chain socket of sprocket. Pulverized coal contains a little sharp and hard sand, which will cause the material on the surface of sprocket to fall off during friction, which is abrasive wear. Abrasive wear is related to hardness of friction material and abrasive. 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, high-speed wear of friction material is caused, because pulverized coal is mixed with a little sharp and hard sand, which is also one of the main reasons for accelerating sprocket wear.