Excavator Undercarriage Parts EX300 Sprocket For HITAHCI?>
Product origin :Quanzhou Fujian China
Delivery time :30days
Supply capacity :20000pcs
The compact structure of EX300 sprocket can realize large transmission ratio, high efficiency and long service life. Chain drive has the characteristics of high sprocket teeth and chains participating in meshing at the same time, large sprocket cogging arc and small gear stress concentration. Therefore, the EX300 chain drive has a large load carrying capacity and the sprocket surface wear is relatively light.
Causes of sprocket wear
The causes of severe wear of the sprocket and socket are as follows:
1, The larger the adhesive wear load, the higher the surface temperature, and the more severe the adhesion phenomenon. For metal materials with a certain hardness, wear test under different pressures has obtained the graph of the relationship between the wear rate and the pressure. When the pressure reaches more than 1/3 of the material hardness, severe wear will occur. According to the stress distribution diagram, it can be known that the maximum stress contact point is the maximum pressure point, and the 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 hardness of the material, so adhesive wear is not the main form of sprocket wear.
2, contact fatigue wear
The friction contact between the sprocket and the chain is alternating contact stress, and it is easy to form fatigue pitting on its friction surface. The index for judging the contact fatigue strength of a metal is the contact fatigue limit, that is, the maximum stress at which pitting does not occur under a certain number of stress cycles. The contact fatigue limit of 40Cr after surface hardening σ0H = HRC17 +200, σ0H = 1016MPa was calculated. According to the stress distribution diagram, the maximum stress value of the sprocket chain socket is 884.4 MPa. Its value is very close to the allowable contact fatigue limit of the sprocket surface. At the maximum stress, it is relatively easy to cause pitting failure. However, due to the poor lubrication conditions of the sprocket and the chain, pitting cannot be formed before, which has already 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 the sprocket.
3, abrasive wear
Because the chain inevitably comes into contact with pulverized coal, a small amount of pulverized coal is stuck on it, and it is brought to the contact point of the sprocket chain. The pulverized coal contains a little sharp sand, which will cause the surface material of the sprocket to fall off during friction. This is abrasive wear. Abrasive wear is related to the hardness of the friction material and the hardness of the abrasive. From the impact diagram of abrasive hardness on wear, it can be seen that when the hardness of the abrasive is close to the hardness of the friction material, it causes high-speed wear of the friction material, because the coal powder is mixed with a little sharp sand, which is also one of the main reasons to accelerate the wear of the sprocket