OPTIMISATION OF AUTOMATIC DOSED MOULD FILLING WITH FERROMAGNETIC POWDERS

Abstract

The effectiveness of the technique for automatic dosed mould filling with fine ferromagnetic powders without natural fluidity is experimentally proved in the paper. In order to obtain steady powder fluidity, disperse medium in the hopper of the considered device is affected by variable 50 Hz gradient magnetic field with vertical induction lines and higher gradient in the area of stimulated fluidity formation and constant magnetic field with horizontal induction lines. At certain magnetic fields parameters, disperse medium passes to a dynamically steady suspended state thus forming a magnetic fluidized bed, and powder flows into a dispenser. The paper provides the results obtained in experimental studies of constant magnetic field induction and variable magnetic field gradient influence on the mass flowrate of barium ferrite powders with an average particle size dav of 1 μm and strontium ferrite powders with dav = 1, 9 and 50 μm through a 2 mm hole. Presented experimental dependencies show that for dav = 1 μm barium and strontium ferrite powders the speeds of powder transportation to the dispenser reach their maximum values at a constant magnetic field induction of 15,7 mT and a variable magnetic field induction gradient of 593 mT/m and are equal to 96,9 and 181,1 mg/s, respectively. According to experimental data, the minimal relative mass error of dav = 1 μm strontium ferrite powder flowed in the dispenser is observed at electromagnetic effect modes providing maximal disperse material fluidity and equals to 2,1–2,3 %.