The working principle is to load the raw materials into the silo, and after being transported by the screw of the feed extruder, the relative density of the pellets increases exponentially and is fed into the bite angle of two extrusion rollers. Then the raw materials are squeezed into sheets through the horizontally placed (or vertically placed) rollers, and then rollers with different surface structures are selected according to the characteristics of the material, and the number of teeth on the surface circle, the total width and depth of the journal groove, and the speed ratio of the rollers are changed. Finally, the working pressure required by the material is sent to the rollers through the automatic pressure-maintaining line of the hydraulic control valve, and the parallel rollers can ensure the consistency of the relative density of the material.