Classifying – separating – and assorting solids – Sifting – Elements
Patent
1994-08-24
1996-05-07
Terrell, William E.
Classifying, separating, and assorting solids
Sifting
Elements
209405, 209412, B07B 149
Patent
active
055137563
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to screening apparatus for use in size classifying discrete material. Heretofore, screening apparatus has been provided of the type having a screen box with an upstanding surround within which one or more vertically-spaced stations have been provided each to horizontally carry an elongate screening surface. The action of size classifying material passed into the screen box is effected by vibratory, reciprocatory, or oscillatory means. The or each screening surface has engaging means at longitudinally opposite ends each to be secured to a holding member arranged transversely, one at each longitudinally opposite ends of the station. Desirably, but not essentially, one holding member is fixed and the other holding member is movably adjustable to allow longitudinal tensioning or releasing of a respective screening surface. Replacing worn screening surfaces or changing screening surfaces to give a different grade(s) of material on existing screening apparatus of the above type is time consuming particularly, but not only, in the tensioning aspect of the replacement screening surfaces and this is disadvantageous.
SUMMARY OF THE INVENTION
An object of the present invention is to obviate or mitigate the above disadvantage.
Accordingly, the present invention is a screening apparatus comprising a substantially rectangular screen box supported through a plurality of shock absorbing members from an elongate mounting frame, the screen box having an upstanding wall surround around at least three sides thereof and within which one or more vertically-spaced stations are provided, the or each station being to carry an elongate screening surface having engaging means at each longitudinal end thereof, each engaging means to be secured to a respective holding bar member arranged transversely between opposite sides of the surround and at or near opposite ends of each station, the outer ends of one or both bar members for each station extending out through an opening in opposite sides of the surround to be engagable by means to move the bar members for each station relatively apart to longitudinally tension a screening surface secured thereto, the moving means for each outer end of the or each bar member being powered length-extension means carried in an out-of-use position on respective components of the frame laterally of each opposed side of the surround and each being transferable for mounting to an in-use position on the respective opposed side of the surround between an anchorage and the respective outer end of the bar member., and power means to actuate said moving means.
Preferably, the length-extension means are hydraulically or pneumatically operable ram and cylinder arrangements. The outer end of the cylinder of each arrangement is desirably provided with an apertured lug and the outer end of the ram of each arrangement is desirably provided with a cup.
Preferably also, fixing means are provided to secure each end of a bar when the respective arrangements are in their extended positions.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
FIG. 1 is a plan view of a screening apparatus according to the present invention shown broken longitudinally to indicate various widths;
FIG. 2 is a side view; and
FIG. 3 is a side view of a detail of a fixing means.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to the drawings, a screening apparatus comprises a rectangular screen box 10 supported through a plurality of shock absorbing members 12 from an elongate rectangular mounting frame 14.
The screen box 10 has an upstanding wall surround 16 around at least three sides thereof, ie. one end 18 and two opposed sides 20, and within the area defined by said sides one or more vertically-spaced stations 22 (two are shown in this embodiment) are provided.
Each station 22 is to carry an elongate screening surface 24 having engaging means at each
REFERENCES:
patent: 3655045 (1972-04-01), McAllister, Jr.
patent: 3968033 (1976-07-01), Illemann et al.
patent: 4319992 (1982-03-01), Davis et al.
patent: 4420391 (1983-12-01), Sharki
patent: 4655907 (1987-04-01), Ando
McKillion Liam
McMahon Frank
Greigg Edwin E.
Greigg Ronald E.
Nguyen Tuan
Powerscreen International Distribution Limited
Terrell William E.
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