Abstract: [Objective] In order to improve the design of the mill grinding disc, the fracture process of grinding the wood chips into fibers by the hot mill was studied in this paper. Based on ADAMS and ABAQUS, the process of grinding the wood chips by the hot mill was numerically simulated, and the process of gradual fracture of the wood chips with the force was explored. When the angle between the grinding and grinding teeth of the moving and stationary discs is constant, the amount of field change was recorded for the distance R from the wood piece to the center of the spindle. The influence of broken area size of the grinding piece on the energy consumption of fiber separation was theoretically analyzed.[Method] Combined with the theory of fracture mechanics, the method of numerical simulation is used. When the angle between the teeth of the moving and stationary discs α is 15°,the numerical simulation method is applied to solve the distance R between the wood chips and the spindle center by using ADAMS software to obtain R=370, 390, 410, 430, 450 mm in five cases, the size of the grinding pressure F_m and the shear force F_r. Then use ABAQUS software to load it on the wood chip and numerically simulate the fracture process.[Result] The ADAMS software was used to simulate the working process of grinding the wood chips by the hot mill, and the simulation result of the grinding pressure F_m and the shearing force F_r of the wood chips α=15° and R=450 mm were obtained. The field variable output result of α=15° and R=450 mm were obtained by using ABAQUS software. The variation trend of Mises stress, normal stress, Magnitude and node displacement of wood chips under different conditions was studied by using Excel scatter plot and regression analysis chart.[Conclusion] 1) The damage form of the wood chips during the grinding process is mainly separated by the shear force F_r along the transverse direction of the wood chips. Therefore, during the structural design and optimization analysis of the grinding plates, the grinding teeth should be increased as much as possible. The force of the cutting force F_r makes the fracture degree of the wood chip in the crushing zone more complete, and reduces the energy consumption of fiber separation in the rough grinding zone and the fine grinding zone. 2) When the hot mill grinds the wood chips, the larger the distance R from the wood chips to the center of the main shaft, the larger the area of the crushing area, the easier the fracture of the wood chips is. The reasonable design of the area of the crushing area of the grinding plate can reduce the energy consumption of fiber separation. 3) Using ABAQUS to simulate the field variable output when the distance from the wood chip to the center of the spindle is not equal, the influence of the area of the crushed area on the fiber separation energy consumption is theoretically analyzed, which can guide the optimized design of the grinding piece.

Key words: hot grinding, wood fracture, fiber separation, the numerical simulation