Alfa-laval Separation Ab

Ola Bjorklund

George L Souter

Alexander F Ritchie

A vibratory screening apparatus has two vibrator motors (19, 20, 19', 20') having respective out-of-balance weights arranged to produce substantially linear vibratory movement when, in use, these motors (19, 20, 19', 20') are running in mutually opposite directions, an electrical control means (37) connected to the motors (19, 20, 19', 20') and is selectively operable between a non-running mode in which both motors (19, 20) (19', 20') are stopped and two running modes in one of which both vibrator motors (19, 20, 19,' 20') run in mutually opposite directions to produce substantially linear vibratory movement and in the other of which at least one of the motors (19, 20, 19', 20') is rotationally reversed and both motors (19, 20, 19', 20') run to produce orbital vibratory movement. In a preferred arrangement, the out-of-balance weights (39, 42) in at least one (20) of the vibrator motors (19, 20) are adapted so that in one of the running modes the respective out-of-balance forces are mutually substantially equal, and in the other of the running modes the out-of-balance forces are mutually unequal. Alternatively, there is provided coupling means (47, 48), (49) for imposing rotational synchronization of the vibrator motors (19', 20') as required.

Vibratory screening apparatus

In a vibratory screening apparatus, a withdrawable lower fine mesh screen assembly (17) has a screen unit (19) releasably mounted on a grid/frame structure (20). The screen unit (19) has a sheet (21) of mesh material bonded to a grate or lattice (22) of a yieldable material such as a hard rubber, and this lattice (22) and the edges of the mesh (21) are also fixed to relatively rigid side members (23) which are mutually free each from the others. In the structure (20), a rigid grate of support bars (26) supports the lattice (22) with a sliding contact interface, and a frame (28) incorporates pneumatically actuated tensioners (30) and clamps (34A, 34B) respectively for tensioning/locking the screen unit (19) and coupling the screen assembly to the vibratory structure. The tension in the screen unit (19) is adjustable whilst on the structure (20) by virtue of the yieldability of the lattice (22) and its sliding contact interface with the support bars (26). Away from the screen assembly, the screen unit (19) is relaxed and less vulnerable to damage or deterioration of tensioning quality.

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Alvsjo, Sweden

Ola Bjorklund