Analysis of sprocket wear of scraper conveyor in compartment scraper machine

Van Scraper Machineis a continuous transport equipment for conveying scattered materials with the help of a moving scraper chain. The van scraper machine is mainly used for the transportation of economic PU mining face in medium and low thick coal seam. The van type scraper machine has the characteristics of compact structure, simple transmission, convenient installation and maintenance, stable work, flexible process layout and so on, it can not only transport horizontally, but also tilt the conveyor, can be used on a single machine, can also be used in a number of joint use. The sprocket is one of the important parts of the van scraper machine, and its characteristics have a direct impact on the service life of the van scraper machine. The sprocket drive used in sprocket wear analysis is a common towing sprocket, which has a relatively large sliding motion in the meshing place, and the working conditions are bad, which will produce more serious wear.

The causes of severe wear and tear in the sprocket chain of the compartment scraper are as follows:

（1The larger the adhesion wear load, the higher the surface temperature, the more serious the adhesion phenomenon. For the hardness of metal materials, wear tests at different pressures to obtain the relationship between wear rate and pressure graph, when the pressure reaches the hardness of the material1/3At the above time, severe wear and tear will occur. According to the stress distribution diagram, it is shown that the maximum stress contact point is the maximum pressure, and its value is884.4 MPa。 Because the quenching hardness at the chain isHRC48~52, the corresponding hardness value is4800MPa。 Therefore, the pressure is much less than the hardness of the material1/3, so adhesion wear is not the main form of sprocket wear.

（2) Contact Fatigue Wear

The friction pair between the sprocket and the chain is alternating contact stress, which is easy to form fatigue pitting on the friction surface. The index to judge the fatigue strength of metal contact is the contact fatigue point, that is, the large stress without pitting phenomenon under the stress cycle number.40CrTreatment of contact fatigue point by surface quenching0H=HRC17 +200, Calculated Sigma0H=1016MPa。 According to the stress distribution diagram, the large stress value of sprocket chain is884.4 MPa。 Its value is very close to the contact fatigue point allowed on the sprocket surface, in the larger stress, it is more easy to cause pitting failure. However, due to the poor lubrication conditions of the sprocket and chain, pitting too late to form, has caused wear and tear, 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 can not be reduced contact with pulverized coal, its adhesion to a little pulverized coal, was brought to the sprocket chain contact, pulverized coal contains a little sharp hard sand, in the friction process will cause the sprocket surface material shedding, which is abrasive wear. Abrasive wear is related to the hardness of friction materials and the hardness of abrasives. The influence of abrasive hardness on wear shows that the hardness of abrasive is close to the hardness of friction material, causing high speed wear of friction material, because pulverized coal mixed with a little sharp hard sand, which is also one of the main reasons to accelerate the wear of the cabin scraper sprocket.