US 3647068 A
Screening mechanism includes two systems of screen-carrying members, the two systems, in static condition thereof, extending in substantially the same horizontal plane, the carrying members being disposed spaced from one another in a given direction and substantially in transverse alignment with one another in the given direction, the carrying members of one system being in respective alternate arrangement with the carrying members of the other system, a screening member comprising a web, at least partly deformable by gravity, carried by the carrying members, each of the carrying members of one of the systems being connected by the screening member to the carrying members of the other system adjacent thereto, and means for relatively moving the two systems in the given direction whereby the spacing between the adjacent carrying members is continually varied in the dynamic condition of the systems, and the screening member is deformed in accordance with the varied spacing between the carrying members.
Description (OCR text may contain errors)
United States Patent Wehner 1 Mar. 7, 1972  CARRYING MEMBERS FOR DEFORMING WEB SCREENS  Appl. No.2 778,857
Related US. Application Data  Continuation of Ser. No. 488,964, Sept. 21, 1965,
 Foreign Application Priority Data Sept. 26, 1964 Germany ..W 37612  References Cited UNITED STATES PATENTS 173,074 2/1876 Slagle ..209/382 X 697,360 4/1902 Petilt 2,410,147 10/1946 Bleeke 2,443,543 6/ 1948 Peterson ..209/382 FOREIGN PATENTS 0R APPLICATIONS 13,441 871%97 Great Britain.... .,.....g09/310 24,940 3/ 1906 Germany ..209/ 310 670,204 9/ 1963 Canada... ..209/ 396 685,105 4/1964 Canada... ..209/396 691,264 7/1964 Canada ..209/ 396 Primary Examiner-Frank W. Lutter Assistant Examiner-Robert Halper Attorney-Curt M. Avery  ABSTRACT Screening mechanism includes two systems of screen-carrying members, the two systems, in static condition thereof, extending in substantially the same horizontal plane, the carrying members being disposed spaced from one another in a given direction and substantially in transverse alignment with one another in the given direction, the carrying members of one system being in respective alternate arrangement with the car rying members of the other system, a screening member comprising a web, at least partly deformable by gravity, carried by the carrying members, each of the carrying members of one of the systems being connected by the screening member to the carrying members of the other system adjacent thereto, and means for relatively moving the two systems in the given direction whereby the spacing between the adjacent carrying members is continually varied in the dynamic condition of the systems, and the screening member is deformed in accordance with the varied spacing between the carrying members.
14 Claims, 19 Drawing Figures PATENTED MR 7 i972 SHEET 3 BF 5 Fig.9
PAIENTEDMAR 7 I972 3. 647. 068
sum u [1F 5 PATENTEDIAR 7 I972 SHEET 5 0F 5 Fig-l8 Fig. 19
CARRYING MEMBERS FOR DEFORMING WEB SCREENS This application is a continuation of application Ser. No. 488,964 filed Sept. 21, 1965 and now abandoned.
This invention is concerned with screening mechanisms, and is a modification of the invention disclosed in German Pat. No. 1,131,162.
According to the present invention, a screening mechanism has two systems of screen-carrying members; the two systems lying substantially in the same horizontal plane, the members of the two systems when viewed in plan, lying parallel to each other, being spaced laterally apart, and lying in alternate arrangement, the two systems being mounted for lateral relative movement, each member being linked to each of the adjacent members which are both of the other system by a screening member, the relative movement being such, that, when viewed in plan the lateral distance between adjacent carrying members varies continuously, and the screening member being such that it deforms when viewed along the length of its carrying members.
The invention is best understood from a description of the embodiments shown in the accompanying drawings in which:
FIGS. I and 2 show respectively an end and a side view of one embodiment;
FIGS. 3, 4 and 5 illustrate different modes that the relative movements of the two systems can have;
FIGS. 6, 7 and 8 respectively show in side and end .view and in plan a second embodiment;
FIG. 9 shows in plan and in front view a third embodiment; and,
FIG. 10 shows a further embodiment;
FIG. 11 a modification of this;
FIG. 12 shows partly sectioned a form of screening member in its two extreme positions;
FIG. 13 shows another arrangement of the screening member in a manner similar to FIG. I2;
FIGS. 14 and 15 show in side view and perspective a further screening member;
FIG. 16 shows cleaning members mounted on to a screening member; and,
FIG. 17 shows two views of a combination of screening members, the two views being taken at a phase interval of 90;
FIG. 18 shows another arrangement of the screening member;
FIG. 19 shows an alternative arrangement of a cleaning member.
Referring to FIGS. 1 and 2, the screening mechanism consists essentially of two frame systems I and II which are mounted for oscillatory motion on springs F, the oscillations arising from a cam or eccentric E mounted on drive shaft W. In this embodiment, the two oscillations are in the same direction but are displaced in phase by 180 with respect to each other. On each frame system I, II are bars lying transversely to the length of the mechanism; these constitute the screen carrying members. As such a mechanism is commonly used to convey material as well as screen it, these may be described in the art as lying perpendicular to the screening (or conveying) direction. Their circular motion about their longitudinal axes is shown by broken lines in FIG. 2. To the bars are attached the screening members; having the form of flexible sheets; they thus form screening areas lying between the individual bars. Because of the bars continuous circular movement and/their consequent constantly changing spacing,
the screening areas also continuously change in width so thatthe screen alternately hangs down and then is stretched. In FIG. 2 the shape of the screen is designated by a solid line in one extreme condition, as and by a broken line in the other condition as 2, being displaced from the first by a phase angle of 180. It is evident that a temporarily stretched zone of the sieve surface is followed by a slack zone and vice versa.
It is understood that within the machine arrangement shown there may be several such screening members arranged one after the other; it may also readily make use of other forms of screening means.
FIG. 3 shows a side view of two adjacent screening members, and the members carrying them; the two extreme conditions of the relative movement of the two systems are shown shaded and in broken line respectively, and the mean.condi tion of the carrying members is also shown in broken line, lyingas expected, between the two extreme positions. The two adjacent screening areas are seen to lie respectively, considered from left to right, between a bar of system I and a bar of system II; and the .bar of system II and a second bar of system I. The widths of these two areas, for description purposes, are logically denoted by the suffixes I II and II I respectively.
The means or natural widths of the areas are seen to be V, and V instantaneous values of .the widths are denoted by H, and H Shown in full lines and shaded areas is the situation of the bars and screening members corresponding to the maximum spacing between the left pair, which is coincident with the minimum spacing between the right pair. These distances are denoted by H, n max. and H min. After a further rotationof the .shaft W through 180, the screen bars are in the position shown in the broken lines. Because of the closing movement of the screen bars of both frame systems I, II during this period, the screen hangs down slack by an increasing amount until it reaches the extreme position At the other extremity it is in the position s, which corresponds to the greatest distance between adjacent bars and where it is more or less stretched or stressed. The circle shown in FIG. 3 with diameter h represents in magnitude the oscillatory motion of the two frame systems I, II.
Hence the following equations are valid:
Illustrated in FIG. 4 are four different positions of the frame systems, being displaced from each other by It is clearly evident therefrom that h=2e.
The system of representation in FIG. 5 corresponds essentially to that of FIG. 3. However here the frame system 1 is stationary and the system 11 executes circular oscillatory movements with an amplitude of e=h/2. For this motion, it is seen that;
The construction shown in FIGS. 6, 7 and 8 illustrates one convenient means of achieving the motion of FIG. 5. In those Figures, the screen box of the practically stationary drive system is designated by 3; in the across tube 4 either the drive shaft or the whole drive system may be placed. The second system Sis oscillated by the drive or the eccentric shaft in the cross tube 4. It is supported on the system 3 by means of springs 6. By adding an unbalancing weight, it is possible to set the whole system oscillating on mounting springs 7. Alternatively, the oscillations may arise from an eccentric in the bearing 10. The screen bars 8 of the frame system 3 pass through the sufficiently wide openings provided in frame system 5. The machine may also be used in an inclined position.
FIG. 9 shows a construction for a screening mechanism in which the bars 8, 9 or the screening areas between them, lie in the screening direction. This arrangement has the advantage that the screened material proceeds along the longitudinal troughs which are alternately stressed and released or allowed to hang slack.
FIG. 10 shows the basic construction of a screening mechanism in which the. system 5 oscillates freely on springs 11 and 11' and is driven with a greater amplitude than that of system 3 since the system 3 transfers its oscillations produced by the imbalance drive 12 and 12' to the system 5. From this, the bars 8, 9 of the two systems have advancing and retiring movements relative to each other, which is necessary for the invention.
A construction similar to that of FIG. 10 is shown in FIG. 11. Here again the screening member 13 is driven as a whole by the box 3' which, for example, may be part of a normal eccentric, or vibrating screening machine. It is important here that the other suspended system 13 be of such a mass that when the box 3' oscillates, the total mass supported by the springs or rubber blocks 14 with the bars, may make sufficiently wide swings. The two frame systems l3, 13' moving relatively to each other thus form here a constructional unit which in itself is closed and may be easily mounted on a screening machine of conventional construction.
FIG. 12 shows in part section a screening member in the two extreme positions of its bars, the screening members 15, being of rigid material and being elastic only at their points of attachment on the bars. The attachment may be achieved by vulcanization, adhesives and the like.
In FIG. 13 the crossmembers joining the bars to each other consist of two essentially rigid screening plates, bars or rods which are joined together and to the screen bars by elastic elements 16.
FIGS. 14 and 15 show in side view and diagrammatic perspective a screening member which consists of elastic longitudinal sections 17. The latter are provided with lateral holes in which suitable rod crossmembers 19 of a suitable material, e.g., metal, are introduced with or without play. Insertion allowing for play has the advantage that the rods are subjected to additional movement; effects are thereby created which are useful in the treatment of materials particularly difficult to screen.
For the screening member shown in FIG. 16, which is particularly suited to screening fine dust, the characteristic feature is the freely swinging cleaning bodies, e.g., balls 18, 18', which assist the process; they may be located above or below the actual screening member. The cleaning action of these balls is especially great here because the extremely high upward acceleration of the screening member causes the attached cleaning bodies to be accelerated and then struck against the member whereby freedom from blockage of the screen is much promoted. An intensive cleaning action also occurs when, as seen in FIG. 19, there is a section or crossmember 24 at a higher or different stress above or below the true screen bottom and it strikes against the screen bottom. Such a section may effectively support a fine screen, e.g., one of silk gauze.
In order to expand the application of the invention, for example, when using a screen of elastic transverse elements, the dimensioning of the clamping lengths can be so selected that a stressing and stretching of the screen takes place so that in, for example, a perforated rubber plate used as the screen the openings or their boundaries are subjected to an additional displacing movement. For special cases it may also be of advantage to select clamping lengths such that all the screening member hangs free to a certain extent so that in every case a pocket or trough is formed between the bars to be oscillated. In addition the individual screening members may define openings of the slot type. They may also have a section which varies so that they in their turn lead to difference in elongation and movement.
According to the inclination and arrangement selected for the screen, especially with oscillations, in more or less strongly concave regions, additional process operations may be carried out on suitable materials, e.g., dewatering orpelletising.
Finally in special cases, e.g., when using semielastic screening members, their arrangement and clamping may also be undertaken so that there is always, or in phases, an arcing upwards or convex curvature of the members. FIG. I7 shows in its upper part the median position of such a convex-screen mounted on bars 8, 9, and in its lower part the same screen in an oscillation phase at 90 to it.
FIG. 18 shows in part section a screen provided with convex curved members. The bars 8 have members 20 of plastic or light metal having a pin 20' inserted through them. The member has longitudinal grooves in which the crossmembers 22 are hingedly mounted with prestressed beads 23. With fine screens there may be additional stifi'ening loops or stiffening sheets 21 below the members.
1. Screening mechanism comprising two systems of elongated screen-carrying members, said two systems, in static condition thereof, extending in substantially t e same horizontal plane, said carrying members being disposed spaced from one another in a given direction and substantially in alignment with one another so that the longitudinal axes thereof extend transversely to said direction, the carrying members of one system being in respective alternate arrangement with the carrying members of the other system, a screening member comprising a web, at least partly deformable by gravity, carried by said carrying members, each of the carrying members of one of said systems being connected by the screening member to the carrying members of the other system adjacent thereto, and means for relatively moving said two systems in said given direction transversely to the longitudinal axes of said carrying members so as to vary continually the spacing between the adjacent carrying members in the dynamic condition of said systems, said moving means comprising a rotatable member connected to each of said systems for imparting a circular motion to the axis of each of the carrying members of the respective system, in the dynamic condition of said systems, so that said axis transversesasubstantially cylindrical locus, and said screening member is deformed in accordance with said varied spacing between said carrying members so as to vary the effective screening area of said screening member.
2. Screening mechanism according to claim 1, wherein said circular motion of the axes of said carrying members of both said systems are in the same rotary direction and out of phase.
3. Screening mechanism according to claim 2, wherein said circular motion of the axes of said carrying members of one of said systems is opposite in rotary direction to that of the other of said systems.
4. Screening mechanism according to claim 1, wherein said screening member web is formed of stretchable material.
5. Screening mechanism according to claim 1, wherein said screening member web is formed of flexible material.
6. Screening mechanism according to claim 1, wherein said screening member web comprises a plurality of rigid strips hingedly connected to the adjacent carrying members.
7. A screening mechanism according to claim I, in which the carrying members lie parallel to the length of the mechanism when viewed in plan.
8. A screening mechanism according to claim 1, in which the carrying members lie perpendicular to the length of the mechanism when viewed in plan.
9. A screening mechanism according to claim 1, in which the screening members are of flexible plates formed of material selected from the group consisting of steel and plastic.
10. A screening mechanism according to claim 1, in which adjacent screening members are formed by continuous flexible strips lying substantially perpendicular to the carrying members, the carrying members of both systems passing through them.
11. A screening mechanism according to claim 1, in which each of the opposite ends of a screening member are pivoted in the adjacent carrying member.
12. A screening mechanism according to claim 1, in which a screening member is made up of a combination of materials of different elasticity hingedly connected, at least to each other, by members formed of material selected from the group consisting of plastic and rubber.
13. A screening mechanism according to claim 1, in which a cleaning member is mounted below a screening member so as to knock against the latter when said systems are in dynamic condition.
14. A screening mechanism according to claim 1, in which the screening member is a flexible web and is taut when the two carrying members carrying it are spaced apart a predetermined maximum amount.