DWSK Sprocket

Causes of JIS sprocket wear



JIS sprocket is one of the important parts of the scraper conveyor, and its characteristics have a direct impact on the service life of the scraper conveyor.

Wear analysis of JIS sprocket of scraper conveyor:

Scraper conveyor is a continuous transport equipment that conveys bulk materials by means of a moving scraper chain. SGB-520/22 scraper conveyor is mainly used for transportation of economic general mining face in low and medium thick coal seams. This product has the characteristics of compact and simple structure, stable transmission, convenient installation and maintenance, reliable work, flexible process layout, etc.; it can not only convey horizontally, but also convey inclined; it can be used alone or in combination with multiple units. JIS sprocket is one of the important parts of the scraper conveyor, and its characteristics have a direct impact on the service life of the scraper conveyor. The JIS sprocket used in the JIS sprocket wear analysis is an ordinary traction JIS sprocket, which has relatively large sliding motion at the meshing position, and the working conditions are bad, which will cause serious wear.

Causes of wear

The causes of serious wear of JIS sprocket sprocket socket are as follows:

(1) The greater the adhesive wear load and the higher the surface temperature, the more serious the adhesion phenomenon. For metal materials with a certain hardness, wear tests are performed under different pressures to obtain a graph of the relationship between wear rate and pressure. When the pressure reaches more than 1/3 of the hardness of the material, severe wear will occur. According to the stress distribution diagram, it can be seen that the maximum stress contact point is the maximum pressure, and its value is 884.4 MPa. Because 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 JIS sprocket wear.

(2) Contact fatigue wear

JIS sprocket and chain friction pairs are alternating contact stresses, which are prone to fatigue pitting on the friction surface. The index for judging the contact fatigue strength of metals is the contact fatigue limit, that is, the maximum stress at which pitting corrosion does not occur under a certain number of stress cycles. The contact fatigue limit of 40Cr is σ0H=HRC17 +200 after surface quenching treatment, and σ0H=1016MPa is calculated. According to the stress distribution diagram, the maximum stress value of the JIS sprocket socket is 884.4 MPa. Its value is very close to the allowable contact fatigue limit of the JIS sprocket surface, and it is easier to cause pitting failure at the maximum stress. However, due to the poor lubrication conditions of the JIS sprocket and the chain, pitting corrosion is too late to form and has caused wear. At this time, the main form of damage is wear rather than pitting. Contact fatigue wear is the main form of JIS sprocket wear, which basically determines the service life of JIS sprocket.

(3) Abrasive wear

Because the chain inevitably comes into contact with coal powder, there is a little coal on it, which is brought to the contact point of the JIS sprocket chain socket. The coal powder contains a little sharp sand, which will cause the surface material of the JIS sprocket to degrade during friction. Falling off, this is abrasive wear. Abrasive wear is related to the hardness of the friction material and the hardness of the abrasive. From the graph of the influence of abrasive hardness on wear, it can be seen that when the abrasive hardness is close to the hardness of the friction material, it will cause high-speed wear of the friction material. Because the coal powder is mixed with a little sharp sand, this is also one of the main reasons for accelerating the wear of the JIS sprocket.