Optimization Design of Key Parameters of Forming Parts of an Involute Plunger Type Biomass Ring Die Pelletizing Machine by DEM-FEM Coupled Modeling

Due to the complex motion state of biomass raw materials in the granulation process of involute plunger biomass ring mold granulator, it is difficult to analyze by use of a linear mechanical model. Accordingly, a granulation simulation model of molded parts was established by coupling discrete element (DEM) and finite element (FEM) analyses. The stress and strain results of ring die and involute plunger pressure roller were analyzed. On this basis, it can be predicted that for wood pellet materials, when the pressure angle of the involute plunger involute profile is 20 degrees, the ring mold forming hole length-diameter ratio is 4.5, the forming hole diameter is 8 mm, and the hole cone angle is 90 degrees, the compression force on the wood pellet will be maximized at 7.89 KN, the maximum equivalent force at the ring mold forming hole and the root of the involute plunger pressure roller will be 64.2 and 84.5 MPa, respectively, and the maximum deformation will be 0.000327 and 0.000424 mm, which is within permissible limits. The involute plunger roller is more susceptible to fatigue damage compared with the ring die. By contrast, the ring part is more prone to fatigue damage in the case of a ring die.