Abstract
The movement of spherical particles in a twin roller system for size classification has been studied experimentally. The diameter of the particles used is 600µm. The classification system consists of a feeder, a twin roller unit and containers for collecting particles classified. The two rollers can be set at a desired angle from the horizon. The rollers can be rotated at an arbitrary angular velocity. All the particles that are fed from the feeder move along the gap between the two rollers. As the gap width increases downward, the particles fall down at a point where the gap width exceeds the particle diameter and are collected in containers arranged in a row. The motion of the particles moving along the gap is observed through a high-speed camera connected with a microscope. The image analysis shows that the particles roll down with small jumping, and the rotation of the particles depends on the operating condition of the twin roller system. The particle velocity along the gap varies according to the jumping. The flight time, normal velocity, and distance can be calculated from the velocity difference of the particles before and after the contact with the rollers.
