Classifying – separating – and assorting solids – Sifting – Feeding
Patent
1991-10-25
1993-07-27
Hajec, Donald T.
Classifying, separating, and assorting solids
Sifting
Feeding
198658, 198659, 209247, 209301, B07B 122
Patent
active
052304310
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
The present invention relates to a feeding screw for a vertical screening device of a separator, said screening device comprising a cylindrical, rotatable screen, a bearing means fixedly connected with the screen, and a non-rotatable feeding screw which coacts with the screen and is supported by the bearing means, the feeding screw being connected, via a link extending beyond the cylindrical surface of the screen, to the stationary separator housing, and said feeding screw having a non-yielding helical portion and an elastic helical portion.
Such a device is a disclosed in U.S. Pat. No. 4,957,618 and can be found in e.g. separators according to U.S. Pat. No. 4,534,859.
In feeding screws according to U.S. Pat. No. 4,957,618 it happens however that when screening e.g. granular material which rolls easily, such as rape, a certain amount rolls down the screw along the screw upper side at a distance from the cylindrical surface of the screen, without engaging the screen, and thus without being able to pass through the perforations of the screen. As a result, a granular material can pass through the last screening device without being separated and leaves the separator as waste together with separated refuse. The waste can amount to a few percent.
The object of the present invention is to provide a feeding screw for a vertical screening device which produces a considerably smaller amount of waste as compared to prior art screws.
A further object of the invention is to provide an improved feeding screw which can readily be used in existing separators.
According to the invention, these objects are achieved by a feeding screw as described above, which is characterised in that at least a section of the feeding screw between the uppermost and lowermost portion thereof makes an acute angle with the cylindrical surface of the screen, the upper side of the feeding screw in this section being inclined downwards from the interior of the screw towards the cylindrical surface of the screen.
In experiments with the inventive feeding screw, waste has been produced in an amount of some percent of the waste obtained in connection with the prior art feeding screw for the same granular material.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described for the purpose of exemplification, with reference to the accompanying drawings in which:
FIG. 1 is a longitudinal section of a prior art separator having two vertical screening devices, and
FIG. 2 is an enlarged longitudinal section of one of the vertical screening devices, showing one embodiment of the feeding screw.
With reference first to FIG. 1, the screening device 1 comprises a cylindrical, rotatable screen 2, a bearing means 3 fixedly connected with the screen 2, and a nonrotatable feeding screw 4 which coacts with the screen 2 and is supported by the bearing means 3. The feeding screw 4 is connected, via a link 5 extending beyond the cylindrical surface of the screen 2, to a fixed point 6 in order to keep the feeding screw stationary while the screen 2 rotates. The fixed point 6 is preferably arranged at the stationary housing 31 of the separator, see FIG. 1. For a detailed presentation of a suitable mounting of the link 5 in the screen 2 and in the housing 31, reference is made to the above-mentioned U.S. Pat. No. 4,957,618.
The bearing means 3 for the feeding screw 4 constitutes a fixed connection transferring rotary and torsional forces and positioned between the upper and lower end portions 7 and 8 of the screening device 1 which suitably consist of flanges. The cylindrical screen 2 is, however, fixedly connected with one end portion 7 only, there being a space between the cylindrical screen 2 and the other end portion 8. This space is utilised for the link 5 of the feeding screw 4.
The link 5 of the feeding screw 4 is attached to a flange 9 which is fixedly connected with the feeding screw 4 and positioned directly opposite the end flange 8 and directly opposite a corresponding flange 10 adjacent the cy
REFERENCES:
patent: 2397305 (1946-03-01), Wheat
patent: 3194385 (1965-07-01), Barnese
patent: 4265738 (1981-05-01), Goncharov et al.
patent: 4467910 (1984-08-01), Siwersson et al.
patent: 4534859 (1985-08-01), Andren
patent: 4645590 (1987-02-01), Satake
patent: 4957618 (1990-09-01), Andren
Hajec Donald T.
Lindema Kommanditbolag
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