This paper is the results of an experimental study on the rate of screening per ranged phase of the sliding motion of grains through the screen under the reciprocating, elliptical and circular motions.
This apparatus consists of a continuous vibrating screen with 4 four-bar linkages. The opening size of the screen was 6.90 mm, and the size of sample of soy-bean used for the screening test was 5.66 mm ＜ grain size 6.73mm ＜ screened during ten sec. by the standard testing sieve of a Ro-tap shaker.
The starting and ending condition criteria of grains on the screen surface for these various motions of the screen can be determined from the equations (1. 2. 3. 4), excepting the negative sliding and rolling motions of a grain.
The main results are as follows :
1) Though the optimum frequency varied according to the feeding rate and the oscillating types of the screen, the screening rate of the optimum frequency was decreased with the increase in the feeding rate.
2) In the case of only sliding motion of grains, the rate of screening per sliding ranged phase was nearly constant, though the range phase of sliding motion increased with the increase in frequency.
3) In the case of motion including both sliding and jumping of grains, the ranged phase of sliding was decreased with the increase in frequency.
4) Comparing the sliding motion with the motion including both sliding and jumping the rate of the screening per ranged phase of sliding of the latter was considerably greater than that of the former.
5) It was found that, in order to get a high efficiency, it might be necessary to consider the angle of incidence and the impact force to the surface of the screen for the jumping grains.