Vibrating sureening device for distributing powder with adjustable flow rate

A powder measuring feed apparatus including a feed hopper, a vibratory module formed by a sieve provided for a determined powder size grading and by a first transducer associated with a first resonator, said transducer receiving an a.c. control voltage Vcom allowing it to transmit mechanical vibrations to said sieve in response, means for locking said vibratory module below said hopper, and an electronic control unit arranged to provide said control voltage Vcom, wherein it further includes a second transducer arranged in proximity to said sieve or in mechanical connection therewith, said first and second transducers operating alternately to make the sieve vibrate and to pick up the vibrations from said sieve and in that said control unit includes a stage arranged to receive a measuring voltage Vmes. representative of the mechanical vibrations of said sifter and to adjust the control voltage Vcom of the first transducer in response so as to enslave the powder flow rate value to a predetermined desired value.