Patent Publication Number: US-6698593-B1

Title: Vibratory screen separator

Description:
BACKGROUND OF THE INVENTION 
     The field of the present invention is separators for screening materials using vibratory motion for enhanced screening. 
     Vibratory separators have long been used for the separation of materials, both wet and dry. It is common to use rectangular screen separators and circular screen separators. An example of a rectangular screen separator is illustrated in U.S. Pat. No. 4,582,597, the disclosure of which is incorporated herein by reference. A circular separator is illustrated in U.S. Pat. No. 5,226,546, the disclosure of which is incorporated herein by reference. The above-mentioned vibratory separators are provided with an inflatable and deflatable seal running around the edges of the screen frame to avoid material bypassing the screen with the inflatable seal in the inflated condition and to securely locate the screen with the separator housing. 
     In U.S. Pat. No. 5,226,546, the inflatable seal assists in the facile removal and replacement of screens from a circular separator without disassembly of the entire separator. Screens are subject to wear and, under certain adverse conditions, to rupture. Further, in certain applications, different mesh sizes may be required for the same machine. The quick-change aspect of this device, therefore, provides substantial operational advantage. However, not all applications are best suited for use of an inflatable mechanism or seal. 
     In U.S. Pat. No. 5,456,365, the disclosure of which is incorporated herein by reference, a vibratory screen separator using a resiliently mounted housing has a first wall portion having an upper edge and a second wall portion above the first wall portion having a lower edge. The upper and lower edges may be mutually aligned to define a seat therebetween to receive a screen. The upper and lower edges further include flanges which extend radially outwardly of the housing to receive a clamp band for securely assembling the wall portions. Mounts coupled to the first and second wall portions have a first position with the upper and lower edges of the housing gripping the screen and a second position with the upper and lower edges of the housing mutually displaced from the screen. In the latter position, the screen is released and can be easily accessed for removal and replacement. 
     The device disclosed in U.S. Pat. No. 5,456,365 includes the mounts on the wall portions of the housing. Thus, they are vibrated with the equipment. The equipment is subject to substantial lateral displacement when passing through natural resonance to or from working speeds. Even though these mounts must be driven with the separator housing, increasing the weight thereof, they don&#39;t experience the problem of being stationary equipment adjacent to the separator when the separator housing is passing through natural resonance. Further, they don&#39;t increase the footprint of the system. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a vibratory separator using screens. The separator includes a base and a housing resiliently mounted to the base. The housing is divided into wall portions which fit together with the screens positionable within the housing between the wall portions. A clamp assembly fixes the portions together. A lift system pivotally mounted relative to the base cooperates with one or more brackets on the upper portion of the separator to allow a raising of one portion of the housing relative to another to provide access therebetween for the insertion and removal of screens. A lift of the system includes an arm, an extension device mounted on the arm and a head mounted on the fluid cylinder and shaft. The head is engageable with a bracket when the arm is pivoted into a first, engaging position. 
     In the foregoing combination, the housing portions may be conventionally formed with outwardly extending flanges defining seating for the screen therebetween. The assembly of the wall portions may then be conventionally secured by the clamp assembly such as a clamp band. 
     The foregoing combination may employ two such lifts diametrically positioned of the housing. Each lift may further include a foot fixed relative to the base of the vibratory separator to pivotally mount the arm. 
     Accordingly, it is an object of the present invention to provide an improved vibratory screen separator and system for facilely accessing screen mounting areas between housing portions. Other and further objects and advantages will appear hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a vibratory screen separator with two housing portions. 
     FIG. 2 is a bottom view of the vibratory screen separator illustrated in FIG.  1 . 
     FIG. 3 is a partial side view of the vibratory screen separator of FIG. 1 with a lift illustrated in a displaced position. 
     FIG. 4 is a partial side view of the vibratory screen separator of FIG. 1 with a lift illustrated in a engaged position. 
     FIG. 5 is a partial side view of the vibratory screen separator of FIG. 1 with a lift illustrated in a engaged position with the upper housing portion displaced from the lower housing portion. 
     FIG. 6 is a cross-sectional detail of a bracket fixed to a clamp band. 
     FIG. 7 is a cross-sectional detail of a bracket fixed to a cover for the housing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning in detail to the Figures, the illustrated preferred embodiment employs a circular vibratory screen separator. This separator includes a housing, generally designated  10 , which is an assembly of cylindrical components. By means of resilient members, e.g., springs, which are not shown in the drawings, the separator housing  10  is mounted to a base  12  in a conventional manner. A vibratory generator, also of conventional design and not illustrated, is securely mounted within the lower table  14  of the housing  10 . 
     A lower cylindrical wall portion  16  of the housing  10  is mounted to the table  14 . Conventionally, the table  14  includes an outwardly extending flange. The lower wall portion  16  also includes an outwardly extending flange on its lower edge. These flanges are brought together and securely clamped by a conventional clamp band  18  as illustrated in FIG. 1. A dome  19  is typically welded in place within the lower housing  16  with a discharge port  20  located through the sidewall of the portion  16  to receive screened material from the upper surface of the dome. A second such discharge port  20  is shown in the bottom view of FIG. 2 to be located diametrically around the lower wall portion  16  from the first discharge port  20 . 
     An upper cylindrical wall portion  22  is aligned with the lower cylindrical wall portion  16 . The lower portion  16  includes an upper edge defining an outwardly extending flange  24 . The upper wall portion  22  includes a lower edge defining an outwardly extending flange  26 . These flanges  24  and  26  are mutually aligned and define a seat therebetween for holding a screen  28 . Such screens  28  are typically comprised of a screen frame across which a screen cloth is drawn taut. A gasket  29  may be conventionally placed around the frame to enhance the seal against the flanges  24  and  26 . Reference is again made to U.S. Pat. No. 5,456,365. A clamp band  30  defines a clamp assembly between the upper portion  22  and the lower portion  24 . A discharge port  32  is positioned through the wall of the upper wall portion  22  to receive the material unable to pass through the screen  28  from the top of the screen positioned within the housing between the upper wall portion  22  and the lower wall portion  24 . 
     The housing  10  may include further upper cylindrical wall portions  22  stacked one on top of another in the same manner with associated clamp assemblies  30 . These additional upper cylindrical wall portions  22  would support additional screens  28  at their intersections. Additionally, the housing may include a top (not shown). A top would typically not include a screen mounting position but would include a flange to cooperate with the upper most upper cylindrical wall portion  22  to receive a clamp band  30 . 
     A lift system in the preferred embodiment is illustrated to include two lifts, generally designated  34  which are illustrated as being diametrically positioned about the housing  10 . Each lift includes a foot  36  extending radially outwardly from the base  12  and may be attached or attachable to the base  12 . Each foot  36  includes a pivot mount  38  near its distal end. An arm  40  extends upwardly from each foot  36  and is pivotally mounted at the mount  38 . Pivoting of the arm  40  is limited as can be seen in FIG. 3 to avoid becoming a nuisance and extending into other work space. At the same time, the arms  40  fall within the same shipping footprint as the separator with the arms  40  pivoted inwardly. The arms  40  are to pivot outwardly such that contact with the housing is avoided even under the substantial lateral displacement experienced when the separator housing  10  is passing through natural resonance. 
     An extension device is associated with the upper, free end of the arm  40 . The extension device may be a fluid cylinder and shaft, either hydraulic or pneumatic, a mechanical jackscrew having an upwardly extending shaft, or the like. The shaft of the extension device extends upwardly from the cylinder to mount a head  44 . In the preferred embodiment, the cylinder and shaft  42  is hydraulic. 
     FIGS. 3 and 4 illustrate the two extreme working positions of the arm  40  of the lift  34 . In FIG. 4, the arm  40  is in an engaged position while in FIG. 3, the arm  40  is in a displaced position with the lift  34  displaced away from the housing. FIGS. 3 and 4 also illustrate a first state of the fluid cylinder and shaft  42  with the head  44  in a retracted position. FIG. 5 illustrates a second state of the fluid cylinder and shaft  42  with the head  44  extended away from the arm  40 . 
     Two brackets  46  are located above the lower flange  26  and more specifically are located on the side of the upper wall portion  22 . The brackets  46  each include a slot  48  into which the head  44  can seat. The slot is defined by an upper mount  50  and a lower fork  52 . The fork  52  provides access for the shaft of the cylinder and shaft mechanism  42 . The head  44  is of significant size and is closely received within the slot  48  to stabilize the lifted components from pivoting about an axis extending through the two heads  44 . 
     Alternatively to mounting the brackets  46  to the uppermost cylindrical wall portion  22 , the bracket  46  may be mounted to one of the clamp bands  30  as illustrated in FIG.  6  through welding or other means or to a cover  54  as illustrated in FIG.  7 . It may be noted that the screen frame  56  used at the cover is often a dummy without a screen cloth attached such that all components of the housing are flexible in their assembly. 
     In operation, the vibratory screen separator is used with the arms  40  of the lifts  34  canted outwardly as seen in FIG.  3 . When a screen  28  is to be replaced, the arms  40  are manually pivoted inwardly to engage the heads  44  within the slots  48 . This orientation is illustrated in FIG.  4 . The clamp band  30  is then removed to release the upper cylindrical wall portion  22  from the lower cylindrical wall portion  16 . Once released, the fluid cylinder and shaft  42  can be actuated through the use of hydraulic pressure to raise the heads  44  and in turn the upper cylindrical wall portion  22 . With the upper cylindrical wall portion  22  and the lower cylindrical wall portion  16  mutually displaced, access is provided to the screen  28  for its facile removal and replacement. Once replaced, the hydraulic pressure is removed and the upper wall portion  22  is again lowered into place. The clamp band  30  is replaced and tightened. The arms  40  are then canted outwardly again and the system is ready for further operation. 
     The embodiment and operation illustrated shows servicing of one screen deck. Devices having multiple screens may employ the same system by simply selecting which clamp band is removed if the brackets  46  are on the uppermost component of the housing  10 . In the present embodiment, the lower clamp band  18  may be removed to raise the entire cylindrical wall assembly of the housing  10  from the table  14 . The entire housing could also be lifted to service the springs, the motor or other components. Where appropriate, the brackets  46  may be associated with a top rather than with a sidewall. In that circumstance, a clamp band could be employed between the cylindrical housing wall and the top. Again, a choice can be made as to the components accessed by selecting the appropriate clamp band to be removed. 
     Thus, an improved vibratory screening system has been disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore is not to be restricted except in the spirit of the appended claims.