Abstract
In the previous paper we reported that the internal friction of powder is related to the variation of void during tapping or the powder constant of Nutting's equation. And it was seen that the shearing stress increases pulsatively with the increase of shearing displacement and saturates gradually.
In this study we carried out determination of pulsative vibration of the shearing stress during flowing of powder by the use of modified Green's rotational cylindrical viscometer. The stress of inner cylinder in response to the shearing stress of powder due to the rotation of outer cylinder represented pulsative vibration at early period and got to the constant of amplitude at the later period of rotating time.
From the results of the recording of pulsative flow patterns obtained employing various kinds of powder, it was found that the amplitude of vibration is related inverse proportionally to the cohesive property of powder.
From the analysis of flow pattern could be derived two types of mechanism of flow properties, i.e. the random flowing of each particles and the flowing of the block of powder. Both types of flowing of particles are attributed to the variation of void during flowing.
An empirical dependence of the mean torque on the duration of the experiment can be satisfactorily represented by the relation;
|(T-T∞)/(T∞-T0)|=expKN
where T is the mean torque at any time, T0 the torque at the initial time of the experiment and T∞ the equilibrium torque after long time. N is the number of rotation and K is a constant relating to the speed of rotation and depending on the packing rate of powder. Subsequently the above equation agree to Roller's equation which was obtained from the relation between the variation of density of powder due to tapping and the number of tapping.
