Modeling of a novel vibrospring particle-size distribution analyzer

The design and modeling of a novel technique for particle-size distribution analysis are described In its most basic form, the unit comprises a horizo ntally held closed-coil helical spring that is partly filled with the test powder find sinusoidally vibrated ill the transverse direction. Particle-si ze distribution data are obtained by tretching the spring to known lengths and measuring the mass of the powder discharged fi om the spring resonant f requency. The spring's vibration characteristics, including the dynamic vib ration profile as well as its first harmonic resonant frequency, are predic ted using a viscoelastic model, which is in turn validated by comparison wi th experimental data. Particle-size distribution data are reported in conju nction with a variety of powders including glass Ballotini, grit stone, san d, and sawdust in the size range 30-800 mum. A typical reproducibility is /- 4%.