Abstract：In order to make a comparison between the tyre and cone shaped grinding roller's grinding process in vertical roller mill(VRM), the mathematical model of the tyre and cone shaped grinding roller based on the differential shear theory was built. The functional expression of the materials' thickness in different contact zone was also built. The equilibrium equation of the materials' differential unit and the contact force and contact area of the grinding roller by integral were obtained. By calculation,the relation between different grinding parameters(the thickness of the materials, the working force and the deflection angle of the grinding roller and the contact area were obtained, then the two kinds of grinding rollers were compared. The result shows that with the bigger deflation angle, the greater peak stress the grinding roller suffers. Under the same working condition, the tyre shaped grinding roller has bigger contact area and smaller peak stress.

Keywords: differential shear theory; vertical roller mill; tyre shaped grinding roller; cone shaped grinding roller; mechanics analysis