Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Separating means
Patent
1996-01-31
1997-01-07
Dayoan, D. Glenn
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Separating means
209394, 209673, B07B 114
Patent
active
055907938
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a roll screen with variable screening apertures, comprising axle-fitted rolls which are disposed at variable distances apart, and means for adjusting said distances, said means acting upon all rolls-simultaneously so that the spacing between all rolls will be changed in relation to one another to the same extent.
It is normal with roll screens according to known techniques to drive the rolls so that they transport material and screen material at the same time. Screening is effected by under-dimensioned particles falling down through the screen apertures, these apertures being formed by the axially extending openings defined between the outer surfaces of mutually adjacent rolls. Roll screens are used within many different fields or areas. Examples in this regard include the manufacture of green pellets in the mining industry, sorting of pellets in other fields or areas, and screening different products in the agricultural and foodstuff industries. In this regard, there is a need to be able to vary the screen apertures to comply with the desired end product.
In addition to this need, roll screens that have variable screening apertures are encumbered with the serious problem that all play or clearance is/are accumulated, meaning that the requisite precision strived for when setting-up the screening apertures is lost. The prior publication SE-B-468,832 proposes a roll screen with variable screening apertures which is intended to alleviate this problem. By mounting a cup spring and an anvil device between the blocks on which the roll axles are mounted, an by applying a force, for instance with the aid of a jack, which acts to compress the cup springs, it is possible to change the settings of all screen apertures as the block slides along a rail. However, it would be impossible in practice to adjust the screen apertures to a precise setting by means of the described invention, and to control the distance between adjacent rolls, because the friction acting in the slide blocks in which the roll units are journalled will vary. The problem of maintaining a precise setting in roll screens thus remains.
EP-A1-0418981 describes an arrangement for setting the distance or spacing between all rolls of the roll screen, this arrangement having the form of a mechanism which includes link arms of mutually different lengths connected to the rolls and to one another. This mechanism is relatively complicated and therewith expensive to produce, and rapidly results-in wear on the link arms and the subsequent occurrence of play and gaps.
Another problem is one of making individual adjustments to the screening aperture between two mutually adjacent rolls without affecting the distance between remaining rolls. This may be necessary, for instance, when the outer surface of a roll has been worn down such that the screening aperture becomes too large. The aforesaid Swedish publication also proposes an arrangement for manually adjusting an individual screening aperture with the aid of an adjusting device which acts against the aforesaid cup springs. However, the accuracy of remaining apertures can be changed for the same reason as that given above for the general setting, and consequently this arrangement is unsatisfactory.
The object of the present invention is to overcome the aforesaid problems by providing a roll screen in which all distances between the rolls can be varied in a simple way and can be set or adjusted simultaneously with precision and in the absence of play, as defined in the characterizing clause of claim 1.
Another object of the invention is to provide means which enable the distance between two rolls to be adjusted individually without affecting the distance between remaining rolls, as disclosed in the characterizing clause of claim 15.
Finally, another object of the invention is to provide an improved seal between the roll axles and the drive arrangement, as disclosed in the characterizing clause of claim 14.
Other characteristic features of the invention and advantages afforded ther
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Dayoan D. Glenn
Luossavaara-Kiirunavaara AB
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