Abstract:
A screen for a vibratory separator, the screen including at least two layers of screening material, at least part of the at least one layer of screening material coated with a coating containing nickel or chromium, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first wires including first shute wires and first warp wires, each of the first shute wires at a right angle to first warp wires, each of the first warp wires at a right angle to first shute wires, the second wires including second shute wires and second warp wires, each of the second shute wires at a right angle to second warp wires, each of the second warp wires at a right angle to second shute wires, each of the first warp wires aligned with a second warp wires, and each of the first shute wires aligned with a second shute wire. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 CFR 1.72(b).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to screens for shale shakers and vibratory separators, and, in certain particular aspects, to screens with aligned wires. 
         [0003]    2. Description of Related Art 
         [0004]    Vibratory separators are used in a wide variety of industries to separate materials such as liquids from solids or solids from solids. In the oil and gas industries, shale shakers use screens to treat drilling fluid contaminated with undesirable solids. Typically such apparatuses have a basket, deck, or other screen holding or mounting structure mounted in or over a receiving receptacle or tank and vibrating apparatus for vibrating one or more screens. Material to be treated is introduced to the screen(s) either by flowing it directly onto the screen(s) or by flowing it into a container, tank, or “possum belly” from which it then flows to the screen(s). 
         [0005]    In a variety of prior art screens, screen mesh or screen cloth as manufactured has a plurality of initially substantially square or rectangular openings defined by intersecting wires of the screen; i.e., as made a first plurality of substantially parallel wires extending in one general direction are perpendicular to a second plurality of substantially parallel wires, all the wires defining square or rectangular openings. In placing one such screen mesh or cloth on top of another, it can happen accidentally that wires of one layer are aligned with wires of another layer; but no effort is made to insure that a large portion, a majority, or substantially all wires of one layer are aligned with wires of another layer. In many actual uses, misalignment of wires occurs, resulting in the deformation of desired openings between wires and, therefore, in reduced screen effectiveness, reduced efficiency, and premature screen failure. 
         [0006]    There has long been a need, recognized by the present inventors, for effective screens for shakers and separators. There has long been a need, recognized by the present inventors, for such screens with a substantial portion of aligned wires. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention discloses, in certain aspects, screening assemblies for shale shakers or other vibratory separators which have a plurality of screen wires in each of multiple screen mesh and/or screen cloth layers which are substantially aligned—wires in one layer aligned with wires in another layer according to preselected parameters. In certain aspects wires in such screening assemblies remain aligned during use. The present invention discloses, in certain aspects, a screen for a vibratory separator, or shale shaker, having at least two layers of screening material; the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer above the second layer; the first wires including first shute wires and first warp wires, each of the first shute wires at an angle to first warp wires; the second wires including second shute wires and second warp wires, each of the second shute wires at an angle to second warp wires; each of a plurality of the first warp wires aligned with a corresponding second warp wire according to a preselected wire count ratio, and each of a plurality of the first shute wires aligned with a corresponding second shute wire according to a preselected wire count ratio. 
         [0008]    In certain particular aspects, wire alignment in such screen assemblies with multiple screening layers is facilitated by using screen meshes or cloths with a selected number of wires per inch in each layer, particularly with a ratio of number of wires in adjacent layers which is a ratio of two numbers which are either exact integers or are almost exact integers; e.g., in certain aspects, within ±0.1 of an integer. 
         [0009]    In other aspects of screen assemblies according to the present invention, wires are aligned either one on top of the other vertically or wires are aligned in a line at an angle to the horizontal plane of a screen assembly; and, in one particular aspect, wires in multiple screen layers are aligned along a line which is coincident with a force vector imparted to the screen assembly by vibrating apparatus of the shaker or separator. 
         [0010]    In certain particular aspects, in methods for making a multi-layer screen according to the present invention, multiple layers are carefully stacked together so that wires in different layers are aligned and then, optionally, the layers are connected together (welded, glued, epoxied, adhered, sintered, etc.) to maintain this alignment in subsequent manufacturing steps. 
         [0011]    A vibratory separator or shale shaker, in one embodiment according to the present invention is, according to the present invention, provided with one, two, three or more screens as described herein according to the present invention. The present invention, in certain embodiments, includes a vibratory separator or shale shaker with a base or frame; a “basket” or screen mounting apparatus on or in the base or frame; one, two, three or more screens according to the present invention with wires aligned according to the present invention; vibrating apparatus; and a collection tank or receptacle. In one particular aspect, such a shale shaker treats drilling fluid contaminated with solids, e.g. cuttings, debris, etc. 
         [0012]    Accordingly, the present invention includes features and advantages which are believed to enable it to advance vibrated screen technology. Characteristics and advantages of the present invention described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments and referring to the accompanying drawings. 
         [0013]    What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, other objects and purposes will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide the embodiments and aspects listed above and: 
         [0014]    New, useful, unique, efficient, nonobvious screens for vibratory separators and shale shakers and methods for using them to separate components of material to be treated thereby; in one aspect, systems for shale shakers for treating drilling fluid with solids therein; and 
         [0015]    Such separators and shakers with one, two, three or more useful, unique, efficient, and nonobvious screens according to the present invention with wires in one screen layer aligned with wires in another screen layer. 
         [0016]    Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
         [0017]    The present invention recognizes and addresses the problems and needs in this area and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of certain preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later attempt to disguise it by variations in form, changes, or additions of further improvements. 
         [0018]    The Abstract that is part hereof is to enable the U.S. Patent and Trademark Office and the public generally, and scientists, engineers, researchers, and practitioners in the art who are not familiar with patent terms or legal terms of phraseology to determine quickly from a cursory inspection or review the nature and general area of the disclosure of this invention. The Abstract is neither intended to define the invention, which is done by the claims, nor is it intended to be limiting of the scope of the invention in any way. 
         [0019]    It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated improvements and/or technical advantages and/or elements in claims to this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0020]    A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments. 
           [0021]      FIG. 1A  is a schematic side cross-section view of a screen (shown partially) according to the present invention. 
           [0022]      FIG. 1B  is a top view of the screen of  FIG. 1A  showing three wires therein. 
           [0023]      FIG. 1C  is a schematic side cross-section view of a screen (shown partially) according to the present invention. 
           [0024]      FIG. 1D  is a schematic side cross-section view of a screen (shown partially) according to the present invention. 
           [0025]      FIG. 1E  is a cross-section view of a screen according to the present invention. 
           [0026]      FIG. 1F  is a cross-section view of the screen of  FIG. 1E  at an angle to the view of  FIG. 1E . 
           [0027]      FIG. 2A  is a schematic side cross-section view of a screen (shown partially) according to the present invention. 
           [0028]      FIG. 2B  is a top view of the screen of  FIG. 2A  showing three wires therein. 
           [0029]      FIG. 2C  is a schematic view of a screen (shown partially) according to the present invention. 
           [0030]      FIG. 2D  is a schematic view of a screen (shown partially) according to the present invention. 
           [0031]      FIG. 3A  is a top view of a screen according to the present invention. 
           [0032]      FIG. 3B  is an enlarged top view of part of the screen of  FIG. 3A . 
           [0033]      FIG. 3C  is an enlarged top view of the center of the screen of  FIG. 3A . 
           [0034]      FIG. 3D  is a cross-section view along line  3 D- 3 D of  FIG. 3A . 
           [0035]      FIG. 3E  is a cross-section view along line  3 E- 3 E of  FIG. 3A . 
           [0036]      FIG. 3F  is a top view of a top layer of the screen of  FIG. 3A . 
           [0037]      FIG. 3G  is an end cross-section view of the layer of  FIG. 3F . 
           [0038]      FIG. 3H  is a top view of a middle layer of the screen of  FIG. 3A . 
           [0039]      FIG. 3I  is an end cross-section view of the layer of  FIG. 3H . 
           [0040]      FIG. 3J  is a side cross-section view of the layer of  FIG. 3H . 
           [0041]      FIG. 3K  is a top view of a bottom layer of the screen of  FIG. 3A . 
           [0042]      FIG. 3L  is an end cross-section view of the layer of  FIG. 3K . 
           [0043]      FIG. 4A  is a top view of a screen according to the present invention. 
           [0044]      FIG. 4B  is an enlarged top view of part of the screen of  FIG. 4A . 
           [0045]      FIG. 4C  is an enlarged top view of the center of the screen of  FIG. 4A . 
           [0046]      FIG. 4D  is a cross-section view along line  4 D- 4 D of  FIG. 4A . 
           [0047]      FIG. 4E  is a cross-section view along line  4 E- 4 E of  FIG. 4A . 
           [0048]      FIG. 4F  is a top view of a top layer of the screen of  FIG. 4A . 
           [0049]      FIG. 4G  is an end cross-section view of the layer of  FIG. 4F . 
           [0050]      FIG. 4H  is a top view of a middle layer of the screen of  FIG. 4A . 
           [0051]      FIG. 4I  is an end cross-section view of the layer of  FIG. 4H . 
           [0052]      FIG. 4J  is a side cross-section view of the layer of  FIG. 4H . 
           [0053]      FIG. 4K  is a top view of a bottom layer of the screen of  FIG. 4A . 
           [0054]      FIG. 4L  is an end cross-section view of the layer of  FIG. 4K . 
           [0055]      FIG. 5A  is a top view of a screen according to the present invention. 
           [0056]      FIG. 5B  is an enlarged top view of part of the screen of  FIG. 5A . 
           [0057]      FIG. 5C  is an enlarged top view of the center of the screen of  FIG. 5A . 
           [0058]      FIG. 5D  is a cross-section view along line  5 D- 5 D of  FIG. 5A . 
           [0059]      FIG. 5E  is a cross-section view along line  5 E- 5 E of  FIG. 5A . 
           [0060]      FIG. 5F  is a top view of a top layer of the screen of  FIG. 5A . 
           [0061]      FIG. 5G  is an end cross-section view of the layer of  FIG. 5F . 
           [0062]      FIG. 5H  is a top view of a middle layer of the screen of  FIG. 5A . 
           [0063]      FIG. 5I  is an end cross-section view of the layer of  FIG. 5H . 
           [0064]      FIG. 5J  is a side cross-section view of the layer of  FIG. 5H . 
           [0065]      FIG. 5K  is a top view of a bottom layer of the screen of  FIG. 5A . 
           [0066]      FIG. 5L  is an end cross-section view of the layer of  FIG. 5K . 
           [0067]      FIG. 6A  is a top view of a screen according to the SC  130   8  present invention. 
           [0068]      FIG. 6B  is an enlarged top view of part of the screen of  FIG. 6A . 
           [0069]      FIG. 6C  is an enlarged top view of the center of the screen of  FIG. 6A . 
           [0070]      FIG. 6D  is a cross-section view along line  6 D- 6 D of  FIG. 6A . 
           [0071]      FIG. 6E  is a cross-section view along line  6 E- 6 E of  FIG. 6A . 
           [0072]      FIG. 6F  is a top view of a top layer of the screen of  FIG. 6A . 
           [0073]      FIG. 6G  is an end cross-section view of the layer of  FIG. 6F . 
           [0074]      FIG. 6H  is a top view of a middle layer of the screen of  FIG. 6A . 
           [0075]      FIG. 6I  is an end cross-section view of the layer of  FIG. 6H . 
           [0076]      FIG. 6J  is a side cross-section view of the layer of  FIG. 6H . 
           [0077]      FIG. 6K  is a top view of a bottom layer of the screen of  FIG. 6A . 
           [0078]      FIG. 6L  is an end cross-section view of the layer of  FIG. 6K . 
           [0079]      FIG. 7A  is a perspective view of three layers of a screen according to the present invention. 
           [0080]      FIG. 7B  is a top view of a screen according to the present invention made with the layers of  FIG. 7A . 
           [0081]      FIG. 7C  is top view of a screen according to the present invention. 
           [0082]      FIG. 8  illustrates steps in a method according to the present invention. 
           [0083]      FIG. 8A  is a chart with information regarding certain screens according to the present invention. 
           [0084]      FIG. 8B  is a chart with additional information regarding the screens of  FIG. 8A . 
           [0085]      FIG. 9A  is a perspective view of a screen assembly according to the present invention. 
           [0086]      FIG. 9B  is an exploded view of the screen assembly of  FIG. 8A . 
           [0087]      FIG. 9C  is a top view of the screen assembly of  FIG. 8A . 
           [0088]      FIG. 9D  is a top view of the frame of the screen assembly of  FIG. 8A . 
           [0089]      FIG. 10A  is a top view of a frame for use with screens according to the present invention. 
           [0090]      FIG. 10B  is an end view of the frame of  FIG. 10A . 
           [0091]      FIG. 10C  is an end view of the frame of  FIG. 10A  opposite the end of  FIG. 10B . 
           [0092]      FIG. 10D  is a side view of the frame of  FIG. 10A . 
           [0093]      FIG. 10E  is a cross-section view of a feed end of the frame of  FIG. 10A . 
           [0094]      FIG. 10F  is a cross-section view of a side of the frame of  FIG. 10A . 
           [0095]      FIG. 10G  is a cross-section view of a discharge end of the frame of  FIG. 10A . 
       
    
    
       [0096]    Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. Various aspects and features of embodiments of the invention are described below and some are set out in the dependent claims. Any combination of aspects and/or features described below or shown in the dependent claims can be used except where such aspects and/or features are mutually exclusive. It should be understood that the appended drawings and description herein are of preferred embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the preferred embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         [0097]    As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. So long as they are not mutually exclusive or contradictory any aspect or feature or combination of aspects or features of any embodiment disclosed herein may be used in any other embodiment disclosed herein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0098]      FIGS. 1A-2D  illustrate the definition of “aligned wires.” As shown in  FIGS. 1A and 1B , wires  1 ,  2 ,  3  in multiple screening material layers a, b, c, respectively are aligned with each other vertically. As viewed from above ( FIG. 1B ) the wires  1 ,  2 ,  3  are in line vertically (at a ninety degree angle to the planes of the screen layers) and, as shown in  FIG. 1B , parallel to each other. 
         [0099]    It is within the scope of the present invention to provide a screen assembly with a layer or layers of screen cloth in which wires have a non-round cross-section (whether such a layer is used in a screen or screen assembly without wires aligned or with wires aligned according to the present invention).  FIG. 1C  shows part of a screen assembly according to the present invention with screen cloth layers d, e, f with aligned wires  4 ,  5 ,  6 , respectively. Wires  5  and  6  have non-round (oval) cross-sections. 
         [0100]      FIG. 1D  shows a portion of a screen according to the present invention with screen cloth layers g, h, i with aligned wires  7 ,  8 ,  9 , respectively. Wires  7  (oval) and  8  (rectangle with rounded corners) have non-round cross-sections. 
         [0101]    As shown in  FIGS. 2A and 2B  the wires  10 ,  11 ,  12  of screening material layers d, e, f, respectively are aligned with each other on a line that is at an angle to the plane of the screen layers (the plane of a screen assembly with such layers; e.g. as shown at an angle at about 45 degrees to the screen assembly plane). As viewed along this line the three wires  10 ,  11 ,  12  would appear as in the view of the wires  1 ,  2 ,  3  in  FIG. 1B . It is desirable that the wires (e.g.,  1 ,  2 ,  3  or  10 ,  11 ,  12 ) are parallel along their entire lengths. 
         [0102]      FIG. 2C  shows a screen with layers m, n, o with aligned wires  13  (oval),  14  (oval), and  15  (rectangle with rounded corners), respectively, with non-round cross-sections. 
         [0103]      FIG. 2D  shows a screen with layers p, q, r with aligned wires  16  (square),  17  (rectangular) and  18  (rectangle with rounded corners), respectively with non-round cross-sections. 
         [0104]      FIGS. 1A-2D  are illustrative and are meant to show how wires in a particular screen or screen assembly are in alignment, or substantially all the wires are aligned, or the majority of wires in the entire screen layers depicted are aligned. 
         [0105]      FIGS. 1E and 1F  illustrate two layers of screening material of a screen SC according to the present invention with aligned wires. In  FIG. 1E  the shute wires of both layers extend left-to-right and the warp wires, shown as circles, go into/out of the page. In  FIG. 1F , the warp wires are shown as extending left-to-right and the shute wires, shown as circles, go into/out of the page. A weaving angle for the top layer is 16.3 degrees; a weaving angle for the bottom layer is 9.7 degrees. Angle N in  FIG. 1F  illustrates a weaving angle. 
         [0106]    For the specific layers shown in  FIGS. 1E and 1F , the numerical measurements indicated are in microns, e.g. “ 113 ” indicates 113 microns. 
         [0107]    As shown in  FIG. 1E  wires a and b of the top layer are perfectly aligned with wires x and y of the lower layer. Also, wire c of the top layer can move toward the lower layer into a space s adjacent a wire z of the lower layer and a wire d can nest in a space r. In effect, wires x “masks” wire a and wire y “masks” wire b so that the screen SC has relatively more open areas than if the wires a and b were offset from the wires x, y, (respectively). 
         [0108]    A ratio of wires spanning  339  microns of the screen SC as viewed in  FIG. 1E  (ratio of top warp wires to lower warp wires) is 3:2 (one half wire a plus wire e plus wire c plus one half wire b—or three wires—above two wires, one half wire x, plus wire y, plus one half wire z—or two wires). As shown in  FIG. 1E , which has a wire count ratio of 3:2 for the top and middle warp wires, then, perfect alignment occurs if every third warp wire on the top layer aligns with every second warp wire of the layer below (as is shown in FIG.  1 E)—i.e., two out of five wires are aligned or 40% alignment is achieved in one direction. In certain aspects of embodiments of the present invention, wires in one layer are aligned with wires in another layer according to the chosen wire count ratio (chosen according to the present invention). Thus with a top to middle wire count ratio of 5:2 in one direction, e.g., for the top and middle warp wires, every fifth warp wire of the top layer aligns with every second warp wire of the layer below—i.e., two out of seven wires are aligned or alignment of 28.5% is achieved in one direction. Thus, according to the present invention, wires are “aligned” when wire count ratios are as selected according to the present invention. 
         [0109]    A ratio of wires spanning  565  microns of the screen SC as viewed in  FIG. 1F  (ratio of top shute wires to lower shute wires) is 5:2. (The top layer has square openings; the lower layer has rectangular openings.) 
         [0110]    As shown in  FIG. 1F  wires f and k of the top layer are perfectly aligned with wires t and v of the lower layer. 
         [0111]      FIGS. 3A-3L  show a screen  300  according to the present invention and parts of it. The screen  300  has multiple mesh layers  301  (top),  302  (middle) and  303  (bottom). As shown in  FIGS. 3B and 3C , the wires of each layer are aligned with the wires of the other two layers. 
         [0112]    In one particular embodiment of a screen  300 , the layer  301  has warp wires  301   a  and shute wires  301   b ; the layer  302  has warp wires  302   a  and shute wires  302   b ; and the layer  303  has warp wires  303   a  and shute wires  303   b . The number of each of these types of wires per inch, wire diameters, and spacings AA, BB, CC, DD, as viewed from above, are as follows: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 No./inch 
                 Diameter (inches) 
                 Spacing (inches) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 301a 
                 111 
                 .00250 
                 .0090 
               
               
                   
                 301b 
                 111 
                 .00250 
                 .0090 
               
               
                   
                 302a 
                 74 
                 .00360 
                 .0135 
               
               
                   
                 302b 
                 44 
                 .00360 
                 .0227 
               
               
                   
                 303a 
                 30 
                 .00750 
                 .0333 
               
               
                   
                 303b 
                 30 
                 .00750 
                 .0333 
               
               
                   
                   
               
             
          
         
       
     
         [0113]      FIGS. 4A-4L  show a screen  400  according to the present invention and parts of it. The screen  400  has multiple mesh layers  401  (top),  402  (middle) and  403  (bottom). As shown in  FIGS. 4B and 4C , the wires of each layer are aligned with the wires of the other two layers. 
         [0114]    In one particular embodiment of a screen  400 , the layer  401  has warp wires  401   a  and shute wires  401   b ; the layer  402  has warp wires  402   a  and shute wires  402   b ; and the layer  403  has warp wires  403   a  and shute wires  403   b  (warp wires across from left/right or right/left,  FIG. 4B ; shute wires intersect warp wires—as is also true for  FIGS. 3B ,  5 B, and  6 B). The number of each of these wires per inch, wire diameters, and the wire spacings EE, FF, GG, HH (as viewed from above) are as follows: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 No./inch 
                 Diameter (inches) 
                 Spacing (inches) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 401a 
                 225 
                 .00130 
                 .0044 
               
               
                   
                 401b 
                 225 
                 .00130 
                 .0044 
               
               
                   
                 402a 
                 150 
                 .00190 
                 .0067 
               
               
                   
                 402b 
                 90 
                 .00190 
                 .0011 
               
               
                   
                 403a 
                 30 
                 .00750 
                 .0333 
               
               
                   
                 403b 
                 30 
                 .00750 
                 .0333 
               
               
                   
                   
               
             
          
         
       
     
         [0115]      FIGS. 5A-5L  show a screen  500  according to the present invention and parts of it. The screen  500  has multiple mesh layers  501  (top),  502  (middle) and  503  (bottom). As shown in  FIGS. 5B and 5C , the wires of each layer are aligned with the wires of the other two layers. 
         [0116]    In one particular embodiment of a screen  500 , the layer  501  has warp wires  501   a  and shute wires  501   b ; the layer  502  has warp wires  502   a  and shute wires  502   b ; and the layer  503  has warp wires  503   a  and shute wires  503   b . The number of each of these wires per inch, wire diameters, and the wire spacings II, JJ, KK, LL (as viewed from above) are as follows: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 No./inch 
                 Diameter (inches) 
                 Spacing (inches) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 501a 
                 90 
                 .00300 
                 .0044 
               
               
                   
                 501b 
                 90 
                 .00300 
                 .0044 
               
               
                   
                 502a 
                 60 
                 .00370 
                 .0067 
               
               
                   
                 502b 
                 45 
                 .00370 
                 .0011 
               
               
                   
                 503a 
                 30 
                 .00750 
                 .0333 
               
               
                   
                 503b 
                 30 
                 .00750 
                 .0333 
               
               
                   
                   
               
             
          
         
       
     
         [0117]      FIGS. 6A-6L  show a screen  600  according to the present invention and parts of it. The screen  600  has multiple mesh layers  601  (top),  602  (middle) and  603  (bottom). As shown in  FIGS. 6B and 6C , the wires of each layer are aligned with the wires of the other two layers. 
         [0118]    In one particular embodiment of a screen  600 , the layer  601  has warp wires  601   a  and shute wires  601   b ; the layer  602  has warp wires  602   a  and shute wires  602   b ; and the layer  603  has warp wires  603   a  and shute wires  603   b . The number of each of these wires per inch, wire diameters, and the wire spacings MM, NN, OO, PP (as viewed from above) are as follows: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 No./inch 
                 Diameter (inches) 
                 Spacing (inches) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 601a 
                 105 
                 .00250 
                 .0095 
               
               
                   
                 601b 
                 105 
                 .00250 
                 .0095 
               
               
                   
                 602a 
                 70 
                 .00350 
                 .0191 
               
               
                   
                 602b 
                 52.5 
                 .00350 
                 .0143 
               
               
                   
                 603a 
                 35 
                 .00700 
                 .0286 
               
               
                   
                 603b 
                 35 
                 .00700 
                 .0286 
               
               
                   
                   
               
             
          
         
       
     
         [0119]    In certain aspects a screen according to the present invention (e.g., but not limited to, the screens of  FIGS. 3A-7A ) are made with multiple layers of screen cloth that are stacked one on top of the other. Ideally each piece of screen cloth as received from the manufacturer has well-defined openings between wires across its entire surface. According to the present invention, to insure that initially the wires of one layer line up with the wires of another layer and remain in this position during the making of a screen or screen assembly, two, three or more layers (however many are to be in the final screen or screen assembly), are carefully positioned one with respect to the other with wires aligned and then they are connected or secured together to hold them in position for further processing. In one aspect, the multiple layers are glued together with one or more amounts of hot melt glue or a line of hot melt glue is applied along one edge of the layers and allowed to set. Alternatively any suitable known glue, epoxy, adhesive or connector(s) (e.g. but not limited to staples, rivets, clips, etc.) may be used. 
         [0120]      FIG. 7A  shows a step in a method according to the present invention in which multiple layers of screen cloth  801 ,  802 ,  803  (three shown) are stacked together for a multi-layer screen  800 . The layers are positioned so that wires in each layer align with wires in the other layers. As shown for a screen  800   a  with layers  801 - 803  in  FIG. 7B , two amounts of adhesive  804  adhere the three layers together to maintain their relative position and the alignment of the wires. One, two, three, four or more amounts of adhesive (e.g. glue, hot melt glue, epoxy, adhesive, cement, plastic, thermoplastic) may be used. 
         [0121]    Optionally, or in addition to the amounts of adhesive  803 , a staple or staples  805  may be used (or a rivet or rivets  807 , as in  FIG. 7C ). Any suitable connector may be used (staple, rivet, clip, screw. 
         [0122]    As show in  FIG. 7C  in a screen  800   b  with layers  801 - 803 , a line of adhesive (e.g., but not limited to, a line  806  of hot melt glue) is applied to the layers  801 - 803  to connect them together. In any embodiment of the present invention an adhesive and/or a connector can be applied manually or by a machine. 
         [0123]    In any embodiment of a multi-layer screen according to the present invention, the layers may be unconnected to each other or any two adjacent or all layers may be connected together. 
         [0124]    In any screen according to the present invention with multiple layers, all layers can have wires of the same diameter or wires in each layer can be of different diameters. 
         [0125]    In certain aspects placing one layer selected according to the present invention on top of another layer selected according to the present invention in combination results in desired alignment (e.g. before the combination of a panel having multiple openings with mesh layers) and/or the force of fluid and/or vibratory force contributes to this alignment. It is within the scope of the present invention by selecting wire screen layers as described above (any embodiment) with wire count ratios according to the present invention to achieve a substantial amount of wire alignment between wires of layers of screening material; e.g., in certain aspects, in a multi-layer screen according to the present invention, to achieve such alignment of at least 30%; of at least 50%; or, in some cases, at least 70%. The percentage of aligned wires in one direction achieved according to the present invention is based on the wire count ratio for that direction. 
         [0126]      FIG. 8  illustrates one method according to the present invention for selecting layers of wire screening material for a screen according to the present invention having aligned wires according to the present invention. The method includes steps  1  to  9 . 
         [0127]    In step  1  a basis point is selected for the top layer of the screen-which determines whether it will be fine or coarse. In one aspect, a screen mesh can be selected with a top warp opening in microns between 25 to 500 microns. 
         [0128]    Once the top warp opening size of the top layer is selected, a wire diameter for wires in the top layer is determined by multiplying the selected top warp opening size by a multiplier, e.g. between 0.1 to 1.1 (based on experience and desirable resulting wire diameters). In one particular aspect, no result finer than 0.0010 inches is used (step  2   a ). 
         [0129]    In step  3  an aspect ratio is selected (in one aspect, in step  3   a , between 0.25 to 4.00) with 1.0 being the aspect ratio for a square opening. Alternatively, in step  3   b , a top layer warp weaving angle is selected, e.g. between 5 and 45 degrees. 
         [0130]    At the end of step  3 , the top layer&#39;s warp opening, wire diameter, and aspect ratio are determined. 
         [0131]    Steps  4 - 6  deal with the middle layer of a three layer screen. In step  4  a count ratio is selected, the count ratio between the top warp wires (per unit length) and the middle warp wires (per unit length), with the numerator and denominator in each ratio being an integer or nearly an integer (e.g. within ±0.1 of an integer); in one aspect, with the integers between 1 and 10 and with the resulting count ratio being 0.1 to 10. Step  4 , therefore, yields the warp count for the middle layer. 
         [0132]    In step  5 , the shute count for the middle layer is determined in a manner similar to that of step  4  for warp count. 
         [0133]    In step  6 , the diameter of the wires of the middle layer is determined by using step  6   a  or step  6   b . In step  6   a  a constant ratio is chosen (based on experience) of top layer wire diameter to middle layer wire diameter, e.g. in a range between 0.2 to 5; or, in step  6   b , a wire diameter is calculated based on results from step  1  (e.g. using a simple formula function based on the numerical result of step  1 ). 
         [0134]    Steps  7 - 9  deal with the lowermost bottom layer of a three layer screen. In step  7  the lowermost layers warp count is determined (e.g. as in step  4 , above for the middle layer), in one aspect, with integers ranging between 1 and 10. In step  8 , the lowermost layer&#39;s shut count ratio is determined (e.g. as in step  5 , above, for the middle layer). In step  9 , the diameter of the wires of the lowermost layer is determined (e.g. as in step  6 , above, for the middle layer). 
         [0135]      FIG. 8A and 8B  show values, measurements, and ratios for screens  1 - 6  according to the present invention determined with the method of  FIG. 8 . “TMDR Value” is top-to-middle diameter ratio. “MBDR Value” is middle-to-bottom diameter ratio. 
         [0136]      FIGS. 9A and 9B  show a screen assembly  900  according to the present invention which has ends  900   g ,  900   h  and a frame  910  on which are secured a plurality of screening layers  901 ,  902 ,  903  with a panel  904  applied to the screening layers. In certain aspects the frame  910  is made of sheet metal, e.g. aluminum, stainless steel, or composite material, or fiberglass. The screening layers  901 - 903  are any suitable known screening material, e.g., but not limited to, screen cloth of multiple spaced-apart wires of stainless steel; and the panel  904  is any suitable material, e.g. mild steel or mild steel coated with cured epoxy. In  FIG. 9B  the layers  901 - 903 , the panel  904 , and the frame  910  are shown somewhat schematically without all the detail of other figures. Any one or two of the layers  901 - 903  may be deleted. 
         [0137]    Peripheral edges of the panel  904  and/or of the screening layers  901 - 903  are connected, secured, and/or adhered to the sides  910   a ,  910   b  and the ends  910   g ,  910   h  of the frame  910 . In one aspect, the panel edges and the screening layer edges are epoxied to the frame. Optionally, the frame  910  has a plurality of holes  912  (and the panel  904  has holes  912   p ) which receive an amount of epoxy that secures the screening layers. The holes  912 , in one aspect, are not aligned with the holes  912   p . In another aspect, the holes  912  and the holes  912   p  are aligned. The holes  912  go all the way through the frame but it is within the scope of the present invention for the holes  912  to project into the frame without penetrating all the way through. 
         [0138]    Optionally, the panel  904  has the majority of its area formed with hexagonal openings  904   a . Optionally, several of these openings, openings  904   b , have a crossbar  904   c , for added strength and wear resistance. The openings  904   c  extend along two sides of the screen assembly at locations of expected relatively high solids impact and/or locations of high accumulation of separated solids. Optionally, the panel  904  has elongated hexagon openings  904   d  (one or, as shown, two rows, or more rows) each with a crossbar  904   e  for added strength and wear resistance. Optionally the panel  904  has areas  904   f  at the end  904   g  adjacent the openings  904   d . Relatively more panel material defines the openings  904   f , hence, they present a stronger area to material flowing thereon. Also, a corresponding shape of the frame  910 , edge  910 f, underlies the areas  904   f  and there is no flow through the areas  904   f . For example, in certain aspects, a screen assembly  900  is positioned on a vibratory separator or shale shaker so that material is fed to the screen assembly to initially fall on the end  900   g  at which the panel  904  has the openings  904   d  and/or areas  904   f  and/or openings  904   b  since the impact of the material and its effects can be greater at a feed end of the screen. An exit end  900   h  of the screen assembly may also have some or all of these areas and openings; as shown, the panel  904  at the exit end  900   h  has areas  904   k  (like the areas  904   f ). Optionally, the frame  910  includes then edge  910   f  which corresponds in shape to the areas  904   f . Optionally, the frame  910  has a plurality of crossbars  910   s  (or crossmembers or cross strips). 
         [0139]    As shown in  FIGS. 9A and 9C , in one particular aspect a screen according to the present invention has, as seen from above, a generally “W” shaped area that includes the areas  904   f , the openings  904   c , the openings  904   d , and a plurality of central openings  904 K (three shown) which cover a portion of the screen area which, in certain uses, is subjected to relatively increased impact, and/or relatively increased solids accumulation and/or wear, and/or relatively larger forces. The openings  904   c ,  904   d  and  904   k  each has a crossbar. 
         [0140]    The openings of the panel  904  may be any desired shape as viewed from above and crossbars may be used with any shape. Any shape may be used for the majority of the panels area with elongated shapes used at certain areas, e.g. at one or both ends. In one particular aspects, the openings  904   a  are regular hexagons with a side-to-side length L of 1.83 inches which is about 8% larger than the side-to-side length of some commonly-used hexagonal panel openings. 
         [0141]    In certain aspects, the elongated hexagonal openings  904   d  have a side-to-side length that is at least 15% greater than a comparable non-elongated hexagon. In one particular aspect, with a side-to-side length between elongated sides which are 1.83 inches apart, the side-to-side length M is 2.198 inches. 
         [0142]    In certain aspects, a panel with hexagon openings with a larger side-to-side length L is used with one or more screening material layers which have wires of relatively larger diameter; e.g., see screens  1 - 6  as described in  FIGS. 8A ,  8 B. 
         [0143]    In certain aspects, in screen assemblies according to the present invention in which wires with relatively larger diameters are used, the wires are spaced-apart a relatively larger distance so that screen open area is not significantly reduced because of the use of larger wires; for example, see screens  1 - 6 ,  FIGS. 8A ,  8 B. 
         [0144]    In certain aspects, screen assemblies according to the present invention have a top layer of wire screening material that has generally square openings and a lower layer beneath the top layer which has non-square rectangular openings. In certain aspects, in such a screen assembly according to the present invention the ratio of wire count (number of wires per unit of length) for the top layer to wire count for the middle layer (or bottom layer if there are only two layers) is a ratio of whole numbers, whether or not there is a whole number of wires per inch in each layer. 
         [0145]    In one particular embodiment the wires of screens are in a 1:1.5 ratio in one direction and a 1:2.5 ratio in the other direction so that across the first direction 1 of 3 openings formed by the top mesh are unobstructed by a wire in the second mesh in that direction, while in the other direction 3 of 5 openings formed by the top mesh are unobstructed by a wire in the second mesh in that direction. In this particular embodiment, when these ratios are maintained, the middle mesh has a count ratio (warp to shute) of 1:1.7. 
         [0146]    In one particular screen assembly according to the present invention (“Embodiment A”), the screen assembly has three layers of screening material, each with wires of stainless steel, including a lowermost layer of tensile bolting cloth (“TBC”), a middle layer with generally non-square rectangular openings; and a top layer with generally square openings. The wire count for each layer and warp and shute wire diameters are as follows: 
         [0000]                                                                                                                Embodiment A                Mesh Type                    Warp       Shute                    Count   Diameter   Count   Diameter                            TBC layer   120   .0026″   120   .0026″           Middle layer   74   .0036″   44   .0036″           Top layer   111   .0025″   111   .0025″                        
In such a screen assembly, the mesh count of the top layer is lower than the mesh count of the TBC layer (with similar wire diameters) so the weaving angles of the top layer are generally less and, therefore, the wires of the top layer can move relatively more than the wires of the TBC layer. Comparable previous known screen assemblies (“B” and “C” below) have the following characteristics for top and middle layers (employing the same TBC lowermost layer):
 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 B: Square Openings: Top &amp; Mid Layers 
               
             
          
           
               
                   
                 Mesh Type 
                   
               
             
          
           
               
                   
                 Warp 
                   
                 Shute 
                   
               
             
          
           
               
                   
                 Count 
                 Diameter 
                 Count 
                 Diameter 
               
               
                   
                   
               
             
          
           
               
                   
                 Top layer 
                 130 
                 .0017″ 
                 130 
                 .0017″ 
               
               
                   
                 Middle layer 
                 100 
                 .0023″ 
                 100 
                 .0025″ 
               
               
                   
                   
               
             
          
         
       
     
         [0000]                                                                                                                C: Rectangular Openings: Top &amp; Mid Layers                Mesh Type                    Warp       Shute                    Count   Diameter   Count   Diameter                            Top layer   170   .0017″   105   .0017″           Middle layer   105   .0025″   64   .0025″                        
The screen assembly of Embodiment A according to the present invention has a top square opening mesh layer which is more stable than the rectangular openings of the C screen assembly since less relative movement of wires occurs with square openings. By using a wire diameter (e.g. 0.0025″) for the top layer that is relatively larger than the wire diameters of the top layers of screen assemblies B and C (0.0017″), the strength of the top layer of the screen assembly according to the present invention is increased. A layer in a screen according to the present invention with “square” openings has openings that are square within manufacturing tolerances; i.e., the square openings may not be exact perfect squares.
 
         [0147]    In any of these screen assemblies according to the present invention the top, middle, and/or lowermost support layers can be calendared. Calendaring can enhance wire alignment. 
         [0148]    In certain screen assemblies according to the present invention (one example being Embodiment A above), the top layer has a mesh wire count ratio of 1:1 (i.e., for a 1:1 ratio, the ratio of the number of wires in one direction is the same as the number of wires in the other direction) or nearly 1:1 (ratio X), e.g. 1:0.9; the wire count ratio (ratio Y) in a first direction of two directions (warp or shute) between the top layer and the layer below the top layer (e.g. a middle layer), is between 1:1.25 and 1:1.75; and the count ratio (ratio Z) between the top layer and layer below the top layer in the second of the two directions is between 2.25 and 2.75. In such screen assemblies the wire diameters of wires in the top layer and the layer below the top layer can be different or the same. In one particular embodiment, specific ratios are as follows: 
         [0000]                                                Ratio X   1:1             Ratio Y   1:1.5           Ratio Z   2.5                        
In certain aspects, wire diameter for wires in a top layer range between 0.0011 to 0.0055 inches and wire diameter for wires in a middle layer range between 0.0011 to 0.0055 inches; and wire diameter ratios, top wire diameter to middle wire diameter, range between 0.72 and 0.68. In certain aspects the wire diameter of wires in a top layer are not smaller than 0.0010″.
 
         [0149]      FIGS. 10A-10G  show a frame  1000  which can be used with the screen of  FIG. 8A  (or any screen according to the present invention). The frame  1000  has sides  1000   a ,  1000   b  and ends  1000   d ,  1000   e . In one aspect the end  1000   d  is a feed end for the screen  1000  and end  1000   e  is a discharge end. The frame  1000  has cross supports  1002  and scalloped edges  1004 . Optionally, a lower series of cross-supports  1006  are also used which extend across the frame  1000  as do the cross supports  1002 . 
         [0150]    The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer above the second layer, each of a plurality of the first wires aligned with a corresponding second wire according to a preselected wire count ratio, a panel combined with the at least two layers of screening material, the panel having multiple spaced-apart openings, a plurality of the multiple spaced-apart openings having a central crossmember extending from a first side of an opening to a second side thereof, said plurality of openings in a pattern on the panel as viewed from above, and a support for the panel and the at least two layers of screening material. Such a screen may have one or some, in any possible combination, of the following: wherein the vibratory separator is a shale shaker for use on a drilling rig; wherein the at least two layers of screening material includes a third layer, the third layer below the second layer and made of a plurality of intersecting third wires, each of a plurality of the first wires aligned with a corresponding third wire, each of a plurality of the second wires aligned with a corresponding third wire; wherein the multiple spaced-apart openings include a plurality of openings with a regular hexagonal shape; wherein a side-to-side length across one of the regular hexagonal openings is 1.83 inches; wherein the plurality of the multiple spaced-apart openings includes a plurality of openings with an elongated hexagonal shape; wherein a side-to-side length across one of the elongated hexagonal openings is 2.19 inches; wherein the pattern includes high impact areas of the screen; wherein the high impact areas include a feed end of the screen, a central area of the screen adjacent the feed end, and two side areas of the screen each adjacent the feed end; wherein the support is a frame; wherein the support has two spaced-apart ends, each of the two spaced-apart ends having a shaped edge, the shaped edge having a shape corresponding to a shape of a portion of the multiple spaced-apart openings; and/or wherein the shaped edges block flow through the at least two layers of screening material. 
         [0151]    The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer above the second layer, each of a plurality of the first wires aligned with a corresponding second wire according to a preselected wire count ratio, a panel combined with the at least two layers of screening material, the panel having multiple spaced-apart openings, a plurality of the multiple spaced-apart openings having a central crossmember extending from a first side of an opening to a second side thereof, said plurality of openings in a pattern on the panel as viewed from above, a support for the panel and the at least two layers of screening material, wherein the at least two layers of screening material includes a third layer, the third layer below the second layer and made of a plurality of intersecting third wires, each of a plurality of the first wires aligned with a corresponding third wire, each of a plurality of the second wires aligned with a corresponding third wire, and wherein the pattern includes high impact areas of the screen. 
         [0152]    The present invention, therefore, provides in at least certain embodiments, a screen for a vibratory separator, the screen having at least two layers of screening material, the at least two layers of screening material including a first layer and a second layer, the first layer made of a plurality of intersecting first wires, the second layer made of a plurality of intersecting second wires, the first layer above the second layer, the first layer having a warp-to-shute wire count ratio A between 0.9 and 1.1, a wire count ratio B in a first direction between the first layer and the second layer is between 1 to 1.25 and 1 to 1.75, and a wire count ratio C in a second direction different than the first direction between the top layer and the second layer is between 2.25 and 2.75. Such a screen may have one or some, in any possible combination, of the following: wherein the ratio A is 1:1, the ratio B is 1:1.5, and the ratio C is 2.5; wherein wires in the first layer range in diameter in inches between 0.0011 and 0.0055, wires in the second layer range in diameter in inches between 0.0011 and 0.0055, and a ratio of diameters of wires of the first layer to diameters of wires in the second layer ranges between 0.72 and 0.68; wherein the first layer and the second layer are calendared together; wherein the vibratory separator is a shale shaker for use on a drilling rig; and/or wherein the at least two layers of screening material includes a third layer of screening material. 
         [0153]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. §102 and satisfies the conditions for patentability in §102. The invention claimed herein is not obvious in accordance with 35 U.S.C. §103 and satisfies the conditions for patentability in §103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. §112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.