US 3565251 A
Description (OCR text may contain errors)
United States Patent  Inventor 2,269,289 1/1942 Schifflin 2,395,138 2/1946 Nicholls 2,587,498 2/1952 Marsh 2,829,772 4/1958 Landes 3,170,875 2/1965 3,390,771 7/1968 Wehner......,,........,.. 1,799,416 4/1931 Gi1lerpie....................... 2,576,746 11/1951 Barnes..........................
Charles S. Pennington. Lombard, Ill.
[211 App]. No. 787,866
Dec. 30, 1968  Patented Feb. 23, 1971 Blaw Knox Company Pittsburgh, Pa.
 Filed  Assignee FOREIGN PATENTS 7/1879 GreatBritain.............,..
Primary Examiner- Frank W. Lutter Assistant ExaminerRobert Hal PLASTIC INTERNAL SCREEN 4 Claims, 3 Drawing Figs.
per Attorney-Parker Carter & Markey  Field 332, 379, 385, 387; 210/consulted ABSTRACT: A sieve assembly for a sifter consisting, in addition to the usual sieve cloth, of only a unitary, one-piece carrier connectabl e to the sieve cloth, said carrier functioning as a container for the sieve cleaning means whereby the conven- S T N m MA 3 mm mA m n H N U m h.
209/382 tional sieve frame and spacer are eliminated.
PATENTEU FEB23 49m sum 1 OF 2 PLASTKC INTERNAL SCREEN This invention relates generally. to sizing or sorting apparatus used in industrial processing, and more specifically to sifting or screening structure for sifting, screening, bolting, rebolting, grading, scalping, separating or classifying depending on the industry and the point in the process at which the operation is performed. For purposes of illustration the invention will be described as applied to a sifter of the type in which a reciprocal and/or rotary motion is imparted to one or more sifting stages within a particle-tight enclosure having inlet and outlet means.
BACKGROUND OF THE INVENTION In prior constructions of the type described generally above each sifting stage has been composed-of a plurality of components, each of which has to be carefully constructed and assembled. Specifically, a single sieve stage must be carefully built up from a sieve cloth, a sieve frame, (which may function as a spacer as well as a supporting frame), a carrier screen,
, and a plurality of cloth cleaners, such as rubber balls which are contained in a plurality of compartments formed when the sieve cloth, frame, and carrier screen are in assembled relationship.
By contrast, by virtue of the construction of the present invention, separate sieve frames and carrier screens are eliminated, along with the attendant manufacturing and assembling intricacies. The result is a sieve assembly which is more economical to manufacture and assemble than prior constructions, and is equally, or more, efficient for its intended purpose than prior constructions.
SUMMARY OF THE INVENTION Accordingly an object of the invention is to provide a sizing and/or sorting assembly which is more economical to manufacture and assemble, and is of equal or greater, efficiency for its intended purpose than prior constructions.
Another object is to provide a sizing and/or sorting assembly having only two basic components in addition to conventional cloth cleaners, said assembly being substantially lighter in weight than prior constructions yet having adequate strength for its intended purpose and being shock resistant and flexible.
Yet another object is to provide a sieve assembly as above described which lends itself to mass production forming techniques as contrasted to prior constructions which required substantial hand labor, and thereby custom work on each sieve assembly.
Yet a further object is to provide a single stage sieve assembly having the aforementioned characteristics and, in addition thereto, is capable of adaptation to a modular system whereby only one, or at most a very few, structurally different sifting assemblies need be stocked by the manufacturer and/or user to provide a sifting apparatus having-any desired number of sifting stages.
Other objects and advantages of the invention will become apparent from the following description of the invention.
DESCRIPTION OF PREFERRED EMBODIMENT The invention is illustrated more or less diagrammatically in the accompanying FIGS. wherein:
MG. 1 is an exploded, perspective view of a single stage sift ing assembly comprising the present invention;
FIG. 2 is a longitudinal sectional view to a larger scale than FIG. l with parts broken away and others shown in section for clarity; and
FIG. 3 is a transverse side view of the sieve carrier of FIG. 2.
Like reference numerals will be used to refer to like parts from FIG. to FIG. in the drawings.
Referring first to FIG. 1, a single stage sifting assembly is indicated generally at 10. Although the term sifting has been applied to the illustrated structure, it will be understood that within the skill of the art the terminology will vary, depending upon the industry to which the invention is applied and the point in the particular process at which the operation is performed. The term sifting" is used herein and in claims as a synonym for other well recognized terms in dissimilar arts for substantially the same operation which is the sizing or sorting of articles which, in an initial condition, are of dissimilar size. The terms screening, bolting, rebolting, grading, scalping, separating or classifying and possibly others may be applied to the process and apparatus in addition to sifting."
The sifting assembly includes a sieve structure indicated generally at 12. The sieve structure 12 includes a sieve cloth 14 which may be made of any suitable material, such as wire, standard tinned or alloyed metals, natural silk, nylon or grit gauze. The longitudinal edges of the sieve cloth 14 are received between strips 16, only the upper one of a pair of which is illustrated in the drawing, which makes possible the stretching of the sieve cloth to place it'under suitable tension. Transverse edge strips are indicated at 18, again only the upper one of the pair beihg illustrated. A- plurality of bendable flaps indicated at 20, 22 extend outwardly beyond the peripheries of longitudinal and transverse edge strips 16 and 18.
A carrier for sieve cleaner means is indicated generally at 24. The carrier, which serves the dual function of a spacer and a means for providing sieve cleaning means, is a unitary onepiece, molded plastic construction. Specifically, the carrier is composed of longitudinal sidewalls 26 and transverse sidewalls 28 which terminate at their upper edges in peripherally continuous, outwardly extending flanges 32,34 respectively. The carrier is divided into a plurality of internal compartments by longitudinally extending ridge structures 38, 40, the maximum elevation of which is no greater than the elevation of the upper surfaces of flange 32,34 which are in abutting contact with the under surface of the sieve structure 12, when in assembled relationship, as best illustrated in FIG. 3. The three longitudinal compartments formed by ridges 38,40 and longitudinal sides 2am further subdivided into smaller compartments by generally transversely extending ridge means 42,44 and 46. Ridge means 42-46 project upwardly to the same elevation as longitudinal ridges 38,40, to provide support for the sieve structure 12. By terminating short of the upper surface of flange 32,34, at the intersections with sidewalls 26,28 and ridge structures 38,40 the transverse ridges 42,44 and 46 provide greater structural rigidity to the carrier, eliminate corner surfaces which might tend to become clogged with material undergoing processing, and contribute to the reduced weight of the structure as contrasted to prior constructions.
The bottom of the compartments are formed by a plurality of small, generally transversely extending ribs, 48, and, in this instance, generally longitudinally extending ribs, 50, which intercept the transverse ribs 48. It should be observed from FIG. 1 that the transverse ribs 48 are spaced apart a distance sufficient to provide easy passage therethrough of the unders which drop through sieve cloth 14.
It will be noted that the carrier lends itself well to mass production forming techniques, such as by vacuum forming since the entire structure may be formed as one piece. lf desired, the carrier in its as formed condition may include a solid sheet material covering spaces formed between ribs 40, this material being easily removed in a single cutting operation.
Sieve cleaning means are indicated at 52, the cleaning means in this instance consisting of a pair of balls contained in each compartment, said balls having the characteristics, with respect to compressability and distortability, of rubber. It should be understood of course that within the scope of the invention any suitable material may be used for the balls, and such materials are today well known in the art. Likewise, only 4 or more than 2 balls may be used, and in practice as many as 4 to 6 have been employed.
As best illustrated in FIG. 3, for example, the sieve cloth contact one with the other. The flaps, 20,22, are bent about a line of weakness 54, or 56 inwardly toward flanges 32,34. Spring clips 58, or other suitable means, may be further employed to securely fasten the sieve cloth to the carrier.
The single stage sieve assembly just described may be placed within a tray structure 60 which includes an unbroken cloth l4 and carrier 24. It will be noted that the surface 62 is, in this instance, formed from essentially two pieces of sheet material 66, 68 which meet at junction line 70 which causes discharge of material toward outlet 64. Longitudinal and transverse walls 72,74 may be of any desired height. Another outlet means is indicated at 76 to receive the overs which are discharged from sieve cloth 14. ln this instance another discharge outlet means is indicated at 78 at to receive material which may have been discharged from a sieve assembly located at one, two or more stages above the illustrated stage.
it will be understood that one or more stages may be assembled one with the other depending upon the number of sizing or sorting operations desired. As is well known in the art, a particle-tight cover may be employed above the uppermost stage which, when clamped to the lower tray forms a substantially airtight or at least particle-tight compartment. A cover will of course have inlet means which may for example consist of a flexible sleeve to accommodate relative movement between the above-described structure and a stationary feed source.
The above assembly, when incorporated in a suitable motive platform which may for example move either in a reciprocal or rotary motion, or a combination of said motions, will efficiently perform the desired sorting and sizing operations.
The use and operation of the invention is as follows.
A carrier means 24 for the sieve cleaning means 52 may be formed from any convenient material by any convenient method. Preferably plastic, or a material having the characteristics of plastic with respect to shock absorption, strength, and flexibility, may advantageously be used. The structure may be formed by any suitable means, such as vacuum forming, and if desired, techniques of that art such as casting a continuous bottom surface, may be employed. in any event, a unitary, one-piece construction has been provided which serves the dual function of providing structure for containing sieve cloth carrier cleaning means when in assembled relationship with sieve cloth l4, and spacing the carrying surface formed by ball supporting ridges 48 any desired distances beneath sieve cloth 14. The sieve 12, which may be of any suitable construction, is secured to the outwardly extending flanges of the carrier by flaps 20, 22 and securely fastened by spring clips or other suitable securing means 58.
When the above-described sieve assembly, which forms in effect a single stage sifting operation, is placed in a support structure, which may for example be a bottom tray 60, and then given a rotary and/or reciprocal sifting motion, a sifting action is performed as is well known in the art. Overs work their way to discharge outlet 76 by virtue of the fact that the entire assembly may be slanted toward said discharge outlet. It will be noted for example that longitudinal wall 73 is of a lesser vertical height than longitudinal wall 75.
Although a preferred embodiment of the invention has been illustrated and described, it will be at once apparent to those skilled in the art that further modifications may be made within the skill of the art. Accordingly, the scope of the invention should be limited not by the scope of the foregoing description, but solely by the scope of the hereinafter appended claims when interpreted in the light of the pertinent prior art.
lclaim: 1. In combination in a sieve assembly, a sieve structure, said sieve structure comprising:
a flexible member having apertures therein through which material to be treated may be passed; edge bounding means forming a framework to which the flexible member is mounted and providing a planar rigidity to the flexible member; and a sieve structure cleaner means carrier, said carrier comrrsm pair of end wall means and a pair of sidewall means, said end wall means and sidewall means terminating at their upper edges, in a common plane, flange means extending outwardly from the upper edges, said flange means lying in a common plane whereby the upper surface of said flange means may be disposed in planar, abutting contact with the lower surface of the edge bounding means of the sieve structure, first ridge means extending from one of said wall means in one of said pairs of wall means to an opposite wall means, the upper surface of said first ridge means providing abutting support for the sieve structure disposed thereabove, second ridge means extending from one of said wall means in the other of said pairs of walls means to an opposite wall means, at least a portion of said second ridge means providing abutting support for the sieve structure disposed thereabove, apertured bottom means, i said wall means, ridge means, and bottom means being unitarily formed and forming a plurality of five-sided compartments, each of said compartments tapering inwardly in the downward direction, said sieve structure cleaning means carrier being composed of plastic, means for connecting the sieve structure to the carrier whereby six-sided compartments are formed, sieve cleaner means within each of said six-sided compartments, means for preventing buildup of treated material at the junctions of the first and second ridge means in the compartments, said buildup prevention means comprising a depression formed in the second ridge means at their junctions with the first ridge means, and the depth of said depressions being less than the height of the sieve cleaner means contained in said compartments.
2. The combination of claim 1 further characterized in that the sieve cleaner means are a plurality of balls, within the sixsided compartments.
3. The sieve assembly of claim 1 further including tray means having a surface underlying the carrier which is unbroken except for outlet means for unders which pass through said carrier.
4. The sieve assembly of claim 3 further including:
cover means adapted to enclose the assembled sieve assembly in particle-tight relationship with the tray means; said cover means having an inlet thereto for the reception of material to be treated; and means for imparting sifting movement to the sieve assembly.