Mixer comprising a housing having filling and emptying openings, two corotating stirrers and drivers for the stirrers, one of the stirrers being arranged centrally in the housing and having at least a drive shaft and at least one transverse beam fitted to the drive shaft and at least one stirring arm fitted at their ends to the transverse beam.
1. A mixer comprising at least a housing ( 1 ) with an inlet opening ( 4 ) and outlet opening ( 5 ), two corotating stirrers ( 2 ) and ( 3 ) and at least one drive for moving the stirrers ( 2 ) and ( 3 ), wherein
one stirrer ( 2 ) is arranged centrally in the housing ( 1 ), said stirrer ( 2 ) comprising at least a drive shaft ( 6 ), at least one transverse beam ( 7 ) fitted to the latter with at least one stirring arm ( 8 ) attached at one end thereof to said at least one transverse beam ( 7 ), and
the other stirrer ( 3 ) comprises at least a drive shaft ( 11 ) and one or more stirring blades ( 12 ), and is arranged eccentrically in the housing ( 1 ) said stirrers ( 2 ) and ( 3 ) being adapted to rotate and brush said one or more stirring blades ( 12 ) and said at least one stirring arm ( 8 ) over one another, with the exception of their end faces.
2. A mixer according to claim 1 , wherein said stirrers ( 2 ) and ( 3 ) are adapted to brush said end faces over the inside wall of the housing ( 1 ).
3. A mixer according to claim 1 wherein said one or more stirring blades ( 12 ) and said at least one stirring arm ( 8 ) are helical in shape.
4. A mixer according to claim 3 , wherein the helixes of said one or more stirring blades ( 12 ) and of said at least one stirring arms ( 8 ) are either all right-handed or all left-handed.
5. A mixer according to claim 1 , wherein the stirrers ( 2 ) and ( 3 ) are configured to provide a symmetry of the stirrers ( 2 ) and ( 3 ) with respect to the rotational speed of their shafts ( 6 ) and ( 11 ) which conforms to the following mathematical relationship (I):
ω
1
ω
2
=
n
2
j
n
1
i
,
(
I
)
in which n 1 denotes the rotational symmetry of the central stirrer ( 2 ), n 2 denotes the rotational symmetry of the eccentric stirrer ( 3 ), ω 1 denotes the rotational speed of the central shaft ( 6 ), ω 2 denotes the rotational speed of the eccentric shaft ( 11 ) and i and j are natural numbers.
6. A mixer according to claim 5 , wherein the number j=1 and the number i=1.
7. A mixer according to claim 5 , wherein the number j=1 and i is >1, with i being prime to n 2 .
8. A mixer according to claim 5 , wherein the number j is >1 and the number i is >1, with i being prime to n 2 and j being prime to n 1 .
9. A mixer according to claim 1 , wherein said one or more stirring blades ( 12 ) have a constant thickness over their radius.
10. A mixer according to claim 1 , wherein the drive for the eccentric stirrer ( 3 ) is arranged on the opposite side of the housing ( 1 ) from the drive for the central stirrer ( 2 ).
11. A mixer according to claim 1 , wherein said at least one stirring arm ( 8 ) of the central stirrer ( 2 ) is at least two stirring arms ( 8 , 9 ) which are connected to one another at their ends via a reinforcing ring ( 13 ).
12. A mixer according to claim 1 wherein said at least one transverse beam ( 7 ) is at least two transverse beams, and additional stirring arms ( 8 ′, 9 ′) are arranged on the undersides of the at least two transverse beams ( 7 ), and at least one additional eccentric stirrer ( 3 ′) is arranged in the housing ( 1 ) in beneath the transverse beams.
13. A mixer according to claim 1 , wherein said at least one transverse beam ( 7 ) has a spiral geometry, which brings about radial conveyance during the rotation of the stirrers ( 2 , 3 ).
14. A mixer according to claim 1 , wherein grooves or ridges, which bring about radial conveyance during the rotation of the stirrers ( 2 , 3 ), are provided on the side of the at least one transverse beam ( 7 ) facing the inside wall of the housing.
15. A mixer according to claim 1 , wherein the outer surface of the at least one stirring arm ( 8 ) is inclined at an angle α to the radius of the central stirrer ( 2 ) of at least 10°.
16. A mixer according to claim 15 , wherein said angle α is at least 20° but less than 80°.
17. A mixer according to claim 16 , wherein said angle α is at least 30° and less than 60°.
18. A mixer according to claim 1 , wherein heating or cooling elements ( 23 ) are fitted to the inner wall of the housing ( 1 ).
19. A mixer according to claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 12 , 13 , 14 , 15 , or 18 wherein said at least one stirring arm ( 8 ) is at least two stirring arms ( 8 , 9 ).
20. A mixer according to claims 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 13 , 14 , 15 and 18 wherein said at least one transverse beam ( 7 ) is at least two transverse beams.