Abstract:
The present invention relates to an apparatus and method for the easy installation or removal of screen elements from a shaker table without the use of tools. Pneumatic cylinders are used to move hold down bars up and down to either allow for screen elements to be installed or removed from the screen bed section assembly, or to clamp them into the screen bed section assembly of a shaker so that the screen elements will not move during shaker operations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC §119(e) of U.S. Provisional Patent Application No. 61/215,092, filed May 1, 2009 and entitled “Screen Clamp,” which is incorporated by reference herein. 
    
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
     N/A 
     NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     N/A 
     REFERENCE TO SEQUENCE LISTING 
     N/A 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to screens for vibratory machinery and more particularly to shake table screening. 
     2. Description of the Related Art 
     Shaker tables are well known to filter solids from liquids in the oil, gas &amp; petroleum industry. Screen elements are used to filter the solids from the liquids, however must be replaced periodically when they become clogged with solids or wear down. Easy installation and removal of the screen elements is hard to achieve. Typical practice is to install and remove the screen elements manually, which can be difficult to accomplish, and interrupts filtering operations for an extended period of time. Thus, there is a need for a method and apparatus that allows for the easy installation and removal of screen elements in a shake table. Unfortunately, such a method and apparatus has not been available to date. 
     BRIEF SUMMARY OF INVENTION 
     In this invention, an apparatus and method are used to easily install and remove multiple curved screen elements used for filtering solids from liquids in a shaker table. The apparatus is comprised of a set of hold down bars that are guided through a carrier frame. The carrier frame holds multiple curved screen elements. The hold down bars are connected to a carrier frame mounting bracket. This entire assembly sits on top of a screen bed that houses pneumatic cylinders. In addition to the carrier frame mounting bracket being connected to the hold down bars, it is also connected to the pistons of the pneumatic cylinder heads located in the screen bed. When the pneumatic cylinders are actuated such that the pistons move upward, the hold down bars are pushed upward allowing the curved screen elements to be easily installed or removed by sliding them out of the carrier frame. When the pneumatic cylinders are actuated such that the piston is in a downward position, the hold down bars clamp the screen elements in place in the carrier frame, thus forming a screen clamp. No tools are required to install or remove the curved screen elements. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       For a further understanding of the nature and objects of the preferred embodiment, reference should be had to the following drawings in which like parts are given like reference numerals: 
         FIG. 1  is a general assembly of a shaker of the present invention; 
         FIG. 2  is an exploded view of a shaker assembly; 
         FIG. 3  is an exploded view of screen bed assembly; 
         FIG. 4  is a cross sectional view of a closed screen bed assembly; 
         FIG. 5  is a cross sectional view of a screen bed assembly with hold down bars in an upward position for screen element removal; 
         FIG. 6  is a cross sectional view of a screen bed assembly with a screen element moved away from the carrier frame; 
         FIG. 7  is an exploded view of a screen element assembly of the present invention; 
         FIG. 8  is a depiction of a hold down bar of the present invention; 
         FIG. 9  is a depiction of a carrier frame of the present invention; 
         FIG. 10  is a depiction of a hold down bar guide of the present invention; 
         FIG. 11  is a depiction of a carrier frame with screen elements of the present invention; 
         FIG. 12  is a depiction of a screen carrier with screen elements removed of the present invention; 
         FIG. 13  is a depiction of a screen element support bar of the present invention; 
         FIG. 14  is a depiction of a screen carrier mounting bracket of the present invention; 
         FIG. 15  is an exploded view of a screen carrier mounting bracket of the present invention; 
         FIG. 16  is an exploded view of a clamp plate assembly in the screen carrier mounting bracket of the present invention; 
         FIG. 17  is a depiction of a screen bed of the present invention; 
         FIG. 18  is a depiction of a portion of a screen bed section of the present invention; 
         FIG. 19  is a depiction of a pneumatic cylinder of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A depiction of the general assembly of a shaker  1  that is used with the apparatus and method of this invention can be seen in  FIG. 1 . The shaker  1  is comprised of a shaker base assembly  6 , which provides a base in which a screen carrier assembly  10 , shaker basket assembly  163  and feed box assembly  47  sits. In general, drilling mud is fed into the feed box assembly  47 , which goes into a shaker basket assembly  163 . The shaker basket assembly  163  contains a screen carrier assembly  10 , which serves as a filter for the drilling mud. At least one motion generator  134  provides shaking motion to the shaker basket assembly  163 . Any solids in the drilling mud are separated by the drilling mud moving through the screen carrier assembly  10 . The strained drilling mud is discharged at the discharge port  29 , and any solids removed from the drilling mud travels forward on top of the screen carrier assembly  10  and will be discharged over the discharge skirt  11 . 
     In this invention, hold down bars  40  are pneumatically operated so that the screen elements  45  can be easily installed or removed in the screen carrier assembly  10 . In order to operate the pneumatic controls, a control panel support stand  73  is mounted to the side of the shaker  1 . An electrical control panel  85  is then attached to the control panel support stand  73 . The control panel support stand  73  contains a pneumatic control panel  74 , which pneumatically controls the operation of the screen carrier assembly  10 . 
       FIG. 2  depicts an exploded view of a shaker  1 . Multiple screen carrier assemblies  10  comprise a screen carrier section assembly  48 , which is set inside the shaker  1 . Each screen carrier section  10  is set inside a screen deck assembly  20  within the shaker  1 , and is operated pneumatically. Each screen carrier section  10  is ideally operated by two pneumatic cylinders  30 , which are operated at the pneumatic control panel  74 . 
     An exploded screen bed section assembly  3  is depicted in  FIG. 3 . Multiple screen bed section assemblies  3  sit one after the other inside the shaker  1 , and on top of the shaker base assembly  6  as shown in  FIG. 1 . In  FIG. 3 , a screen bed section  3  is comprised of a screen bed  31  and an area to house one or more pneumatic cylinders  30 . The screen bed section  3  forms the base of the assembly  3 . Preferably two pneumatic cylinders  30  are connected to each screen bed section  31 . A carrier frame mounting bracket assembly  60  is attached to the screen bed section  31  at the pneumatic cylinder  30  locations. The carrier frame mounting bracket assembly  60  is sandwiched between the carrier frame  50  and the screen bed  31 , with the carrier frame  50  sitting on the screen bed  31 . Hold down bars  40  are inserted through the carrier frame  50  and bolted to the carrier frame mounting bracket assembly  60 . When the hold down bars  40  are lifted to an upward position, curved screen elements  45  can be slid in and out of the carrier frame  50 . After the screen elements  45  are placed inside the carrier frame  50 , the hold down bars  40  can be lowered to clamp the screen elements  45  in place. 
       FIG. 4  shows a cross sectional view of the screen bed assembly section  3  when the hold down bars  40  are in a closed position. In  FIG. 4 , the screen bed section  31  contains pneumatic cylinder holder cups  12 , which house pneumatic cylinders  30 . The pneumatic cylinder holder cups  12  are supported and connected to the screen bed section  31  by pneumatic cylinder holder support brackets  16 . The carrier frame mounting bracket assembly  60  attaches to the screen bed section  31  by bolting a clamp plate  21  to the piston  38  of a pneumatic cylinder  30 . The carrier frame mounting bracket assembly  60  is then bolted to the hold down bars  40 , which are slid through guides  54  located between each screen element  45  in the carrier frame  50 . The carrier frame  50  sits between the screen bed section  31  and the screen elements  45  that are clamped down by the hold down bars  40 .  FIG. 4  shows that the carrier frame front scallop plate  2  sits on the screen bed section  31 , and is also locked into place by the hold down bars  40 . 
       FIG. 5  is similar to  FIG. 4 , except that the hold down bar  40  is in an upward position. The hold down bar  40  is placed in an upward position when the pneumatic cylinder piston  38  of the pneumatic cylinder  30  is actuated and extends upward. When the hold down bar  40  is in an upward position, the screen elements  45  can easily be installed or removed.  FIG. 6  shows the screen element  45  as it is moved either into or out of the screen bed assembly. 
       FIG. 7  shows a detailed view of a screen element  45 . The screen element  45  is comprised of a curved webbed filter  49 , preferably including stamped metal, which is then preferably coated with an epoxy powder coating. A mesh screen  46 , preferably made of wire cloth, is placed on top of the filter  49 , and heated in a heat press until the mesh screen  46  is affixed to the filter  49  and forms the individual screen elements  45 . 
       FIG. 8  shows a detailed view of a hold down bar  40 . Two metal plates, each with its own ledge  41 , are welded together to form a hold down bar  40 . The hold down ledges  41  serve to clamp the screen elements  45  in place when the hold down bar  40  is in a closed position. 
       FIG. 9  is a detailed view of a carrier frame  50 . Each carrier frame includes, for example, two carrier frame side plates  5  and two carrier frame scallop plates  2 , which are welded together to form a frame. The carrier frame  50  sits on top of the screen bed  31 , and supports the screen elements  45 . To better support the screen elements  45 , screen element support bars  52 , preferably two, are welded beneath each scallop in the scallop plates  2  where the curved portion of the screen element  45  will rest. In between where each screen element  45  will rest, a hold down bar guide  54  is welded to the carrier frame  50 . The hold down bar guide  54  provides the location where the hold down bars  40  will move up and down through the carrier frame  50 . As discussed previously, when the hold down bars  40  are in an upward position, screen elements  45  can be easily installed and removed. However, when the hold down bars  40  are in a lowered position through the hold down bar guide  54 , the hold down bar ledges  41  will clamp the screen elements  45  into the carrier frame  50 . 
       FIG. 10  is a detailed view of the hold down bar guide  54 , which is placed between each scallop in the scallop plates  2  of the carrier frame  50 . The hold down bar guide  54  is preferably a u-shaped piece of metal with channels cut so that the hold down bars  40  can slip through the hold down bar guide  54  and connect to the carrier frame mounting bracket assembly  60 . 
       FIG. 11  depicts the carrier frame  50  when the screen elements  45  are in place, and the hold down bars  40  are in the closed position. 
       FIG. 12  shows another view of the screen bed section assembly  3  with the screen elements  45  removed. 
       FIG. 13  is a detailed view of the screen element support bar  52 , which sits at the bottom of each scallop in the scallop plates  2  of the carrier frame  50 . The screen element support bar  52  is preferably metal, and preferably welded to the carrier frame  50 . The use of two screen element support bars  52  is preferred to support each screen element  45  in the carrier frame  50 . 
       FIG. 14  is a detailed view of the screen carrier mounting bracket  60 . Two mounting bracket supports  55  are connected by two clamp plates  21 . The preferable means of connection is by bolting the pieces together, although these pieces of the screen carrier mounting bracket  60  could be one continuous piece or could be connected by weld. Tube brackets  70  are affixed to a tube bracket adaptor  57 , which is in turn attached to each mounting bracket support  55 . Preferably, each tube bracket  70  and tube bracket adaptor  57  is metal, and each is attached to the respective component by bolting the components together. However, it is envisioned that these components could be attached by other means known in the art. 
       FIG. 15  is an exploded view of the screen carrier mounting bracket  60  and shows the preferred embodiment of bolting tube bracket adapters  57  to the mounting bracket support  55 , and mounting tube brackets  70  to the tube bracket adaptors  57 .  FIG. 16  is another exploded view of the screen carrier mounting bracket  60  that shows the preferred embodiment of bolting the clamp plates  21  to the mounting bracket support  55 . 
     The clamp plates  21  sit on the pneumatic cylinder cup holders  4  shown in  FIG. 17 . Each clamp plate  21  is bolted to the pneumatic cylinder piston  38  which is centered inside the pneumatic cylinder cup holder  4 . The hold down bars  40  are bolted to the ends of the tube brackets  70  of the carrier frame mounting bracket assembly  60 . 
       FIG. 17  shows a screen bed  35 , which is comprised of front screen bed sections  32  and side screen bed sections  33 , which make up an overall frame for the screen bed  35 .  FIG. 18  shows how each pneumatic cylinder holder cup  12  is braced by pneumatic cylinder holder support brackets  16 , which are affixed to the screen bed sections  31 , preferably by weld.  FIG. 19  shows a pneumatic cylinder  30 , which sits inside the pneumatic cylinder holder cup  12 . The pneumatic cylinder piston  38  extends through the middle of the pneumatic cylinder holder cup  12  and is bolted to the clamp plate  21  of the screen carrier mounting bracket assembly  60 .