Vibration device for an apparatus for conveying a metal charge to a melting plant

Vibration device for a conveying apparatus to convey a metal charge in a longitudinal direction comprising at least two vibration mechanisms each disposed on opposite sides of said conveying apparatus so as to feed said metal charge, each of said vibration mechanisms comprising a plurality of eccentric masses having their axes of rotation substantially orthogonal to straight lines parallel to the longitudinal direction, wherein each of said vibration mechanisms comprises at least a first plurality of said eccentric masses, the first plurality comprising a first, a second, and a third eccentric mass, the first and third eccentric masses arranged to rotate at a first speed, the second eccentric mass having a double weight with respect to that of the first and the third eccentric masses, the second eccentric mass arranged to rotate at a second speed which is half the first speed, the first, second and third eccentric masses arranged to have their respective mass barycenters aligned along an axis which is parallel to the longitudinal direction when in a first working condition, and a second plurality of said eccentric masses arranged, when in the first working condition, to have their mass barycenters rotated at an angle about their respective rotational shafts to space the respective mass barycenters away from the axis, said eccentric masses of each vibration mechanism being configured and kinematically actuated in reciprocal relation both between the eccentric masses of each plurality, and between said first and second plurality, and also between said vibration mechanisms, in order to determine, during use, a resulting centrifugal force substantially parallel to said longitudinal direction and a transverse component with respect to said longitudinal direction, substantially zero.