| Summary: | In recent years, the demand for fine particle materials has been increasing in various industrial fields such as electronics, chemistry, and medicine. Ball mills are commonly used for the production of fine particle materials, but they have some problems. In particular, when the rotation speed is increased, the contents stick to the inner wall of the container and rotate together. That is called the critical condition, and the efficiency is significantly reduced. The three-dimensional ball mill, which rotate its container with two degrees of freedom, is proposed as a solution to overcome such problems. We found that the critical condition is suppressed by using three-dimensional ball mills. It was also reported that both frictional heat generated during pulverization and particle unevenness are reduced. Although some advantages can be found with this machine, there is few theories that explain what has been happened. In this study, we focused on the mechanism of suppressing the critical condition. First, based on the past study for ordinary ball mills, we created a theoretical formula for three-dimensional ball mills in critical condition. Next, using the formula, we simulated the motion of three-dimensional ball mills. Finally, we compared the simulation with the motion of the actual machine, and confirmed that they agreed well.
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