Patent Publication Number: US-7210582-B2

Title: Screen and screen frame for improved screen to shaker placement, handling and retention

Description:
BACKGROUND 
     Rotary drilling methods employing a drill bit and drill stems have long been used to drill wellbores in subterranean formations. Drilling fluids or muds are commonly circulated in the well during such drilling to cool and lubricate the drilling apparatus, lift drilling cuttings out of the wellbore, and counterbalance the subterranean formation pressure encountered. The recirculation of the drilling mud requires the fast and efficient removal of the drilling cuttings and other entrained solids from the drilling mud prior to reuse. Shaker separators are commonly used to remove the bulk solids from the drilling mud. An essential element of the shaker separators are the shaker screens. Shaker screens are typically composed of a support frame and screen (either pretensioned or perforated plate screen) assemblies. As is illustrated in  FIG. 2  the current state of the art method for securing the shaker screen ( 22 ) to the shaker separator (not fully shown) involves the use of a wedge block clamp ( 24 ) which is an integral part of the shaker separator and a wedge block ( 26 ). As one of skill in the art should know, the screen is placed in position underneath the wedge block clamp and then the wedge block is pounded into position so as to secure the screen to the shaker separator. Unfortunately, the shaking motion of the shaking separator can cause the loosening of the wedge block and thus the loosening of the screen vis-à-vis the shaker separator. Thus there exists a continuing need for improved designs in the support frames for shaker screens that improve the placement and retention of the screen to the shaker. 
     SUMMARY OF THE CLAIMED SUBJECT MATTER 
     The present disclosure is generally directed to a support frame for a shaker screen ( 1 ), the frame includes a first outer longitudinal support member ( 2 ), a second outer longitudinal support member ( 4 ), which is spaced apart from and substantially parallel to the first outer longitudinal support member and one or more inner longitudinal support member ( 6 ), each of which is positioned between and substantially parallel to the first outer longitudinal support member and the second outer longitudinal support member. A first outer lateral support member ( 8 ) is connected to the one end of the first outer longitudinal support member and is substantially perpendicular to the first outer longitudinal support member. A second outer lateral support member ( 12 ) is connected to the other end of the first outer longitudinal support member is substantially perpendicular to the first outer longitudinal support member. Similarly a third outer lateral support member ( 10 ), and a fourth lateral support member ( 14 ) are connected to the second outer longitudinal support member both of which are substantially perpendicular to the second outer longitudinal support member. The screen frame also includes one or more inner lateral support member which is positioned between and substantially perpendicular to the first outer longitudinal support member and the second outer longitudinal support member and which are connected to the one or more inner longitudinal support members. A first lateral support brace ( 18 ), is connected to the first and third outer lateral support members. Similarly, a second lateral support brace ( 20 ), is connected to the second and fourth outer lateral support members. 
     In one illustrative embodiment, the support frame is designed such that the first lateral support brace and the second lateral support brace are positioned to form a wedge block clamping platform on the lateral edge of the support frame. In one preferred embodiment, the wedge block clamping platform is positioned and has a width such that it corresponds substantially to the width of the wedge block thereby enhancing screen clamping to the shaker. 
     Alternatively or in addition, an illustrative embodiment of the support frame is designed such that the combination of the first lateral support brace and the first and third outer lateral support members form a gripping element on the lateral end of the support frame. Similarly, the combination of the second lateral support brace and the second and fourth outer lateral support members form a gripping element on the lateral end of the support frame. When used in combination with each other, the pairs of gripping elements can be used to obtain a firm grip on the screen frame using a human hand or by using a gripping tool, such a gripping hook. The gripping element is preferably positioned and sized such that the support frame, and thus the shaker screen, can be easily gripped for positioning prior to securing to the shaker separator. 
     Additional details and information regarding the claimed subject matter can be found in the following description. 
    
    
     
       DESCRIPTION OF THE FIGURES 
       The present disclosure is made with reference to the following Figures: 
         FIG. 1 , is a top view of an illustrative embodiment of a shaker screen frame as disclosed herein; 
         FIG. 2  is a diagram illustrating the interactions of a state of the art (prior art) screen frame with a wedge block and a wedge block retaining bracket of a shaker separator. 
         FIG. 3  is a diagram illustrating the interactions of a screen frame as disclosed herein with a wedge block and a wedge clock retaining bracket of a shaker separator. 
     
    
    
     DESCRIPTION OF THE CLAIMED SUBJECT MATTER 
     The present disclosure is generally directed to a support frame for a shaker screen and a shaker screen incorporating such a frame. With reference to  FIG. 1 , one illustrative embodiment of a frame for a shaker screen ( 1 ) of the present invention includes, a first outer longitudinal support member ( 2 ), and a second outer longitudinal support member ( 4 ), spaced apart from and substantially parallel to the other. It will be appreciated by one of skill in the art that all of the support members, unless noted otherwise, inherently have a first end and a second end. The frame also includes one or more inner longitudinal support member ( 6 ), each being positioned between and substantially parallel to the first outer longitudinal support member and the second outer longitudinal support member. 
     The frame further includes a first outer lateral support member ( 8 ), substantially perpendicular to the first outer longitudinal support member. One end of the first outer lateral support frame is connected to the first end of the first outer longitudinal support member. A second outer lateral support member ( 12 ), is connected to the second end of the first outer longitudinal support member and is substantially perpendicular to the first outer longitudinal support member. The other end of the support frame preferably mirrors that just described. That is to say, a third outer lateral support member ( 10 ), is connected to the other end of and is substantially perpendicular to the second outer longitudinal support member. Similarly a fourth outer lateral support member ( 14 ), is connected to the second end of the second outer longitudinal support member in a substantially perpendicular manner. The frame further is composed of one or more inner lateral support member ( 16 ) each of which is positioned between and substantially perpendicular to the first outer longitudinal support member and the second outer longitudinal support member. As shown in  FIG. 1 , at least one end of each of the one or more inner lateral support member is connected to the one or more inner longitudinal support member. A first lateral support brace ( 18 ) has a first half end and a second half end. The first lateral support brace is connected at one half end to the second end of the first outer lateral support member; and at the other half end is connected to the second end of the third outer lateral support member. Similarly, a second lateral support brace ( 20 ) has a first half end and a second half end. The second lateral support brace at one half end is connected to the second end of the second outer lateral support member; and at the other half end is connected to the second end of the fourth outer lateral support member. As shown in  FIG. 1 , the above forms a support frame for a shaker screen upon which screening or filtering elements may be supported. As is further shown in  FIG. 1 , the positioning of the lateral support braces and the outer lateral support members can be used to form a pair of gripping elements on the lateral sides of the screen frame. Such gripping elements may be of a sufficient size and design to be gripped by a human hand to assist in the handling of the screen frame. Alternatively, the gripping elements can be sized and designed to be gripped by a gripping tool. Such a gripping tool may be a conventional cargo hook or may be a specially designed tool having a handle and an engaging portion designed to engage the gripping element. Regardless of the gripping tool utilized, the concept is to provide the user the ability to securely and safely grip the screen frame so that it can be handled and positioned as needed. 
     One of the many features of the present illustrative embodiment includes the ability to increases the contact surface area between the wedge block and the screen frame. As is illustrated in  FIG. 2  the current state of the art method for securing the shaker screen ( 22 ) to the shaker separator (not fully shown) involves the use of a wedge block clamp ( 24 ) which is an integral part of the shaker separator and a wedge block ( 26 ). As one of skill in the art should know, the screen is placed in position underneath the wedge block clamp and then the wedge block is positioned so as to secure the screen to the shaker separator. Unfortunately, the shaking motion of the shaking separator can cause the loosening of the wedge block and thus result in the loosening of the screen vis-à-vis the shaker separator. In contrast and as is shown in  FIG. 3 , the present illustrative embodiment of the present invention includes a combination of the two outer lateral support members ( 8  &amp;  10 ) and the lateral support brace ( 18 ) form an increased contact surface area (not shown) for the wedge block ( 26 ). This increased contact surface area substantially increases the frictional contact between the wedge block and the shaker screen. One of skill in the art should immediately appreciate that such an arrangement increases the static frictional energy required to loosen the wedge block during the shaking process. Further it will be appreciated that the positioning of the wedge block serves to seal any gap in the screen formed by the presence of any gripping element without decreasing the effective surface area of the shaker screen. 
     One of skill in the art should understand and appreciate that a wide variety of materials may be utilized for the construction of the above described frame. In one such illustrative embodiment, the frame is constructed of welded metal, such as steel, steel alloys, aluminum, aluminum alloys, and the like which may subsequently be coated with paint, epoxy, thermoplastic and other such protective materials. Alternatively, the frame may be constructed from composite materials including resin based composites, such as: fiberglass/resin; carbon fiber/resin; metal fiber/resin; combinations of these and the like, thermoplastic composites such as fiberglass/plastic; carbon fiber/plastic; metal fiber/plastic; combinations of these and the like; as well as combinations of various composite materials that are suitable for such applications. Finally it should be noted that one of skill in the art would appreciate that the illustrative frames may be cast, stamped, forged, or machined from ferrous and non-ferrous metals, plastics, composite materials and the like. 
     Structurally the frame is preferably made of a tubular material and more preferably all of the components of the frame are substantially made from a tubular material. In one illustrative embodiment, the tubular material is selected from square tubular material, rectangular tubular material, round tubular material, combinations of these and other materials that should be known to one of skill in the art. 
     Formation of a shaker screen utilizing the frames described above should be well known to one of skill in the art. In general, screen elements, which may or may not be pre-tensioned, are secured to the frame. This securing step may be any conventional means taking into account the composition of the frame and the composition and nature of the screen. 
     In view of the above, one of skill in the art should appreciate that one illustrative embodiment of the present invention includes a shaker screen ( 1 ), having one or more screen layers supported by a frame in which the improvement includes the frame as substantially described herein. Further, it should be appreciated that the present invention also includes a conventional shaker separator having one or more shaker screens, in which each of the shaker screens has one or more screen layer supported by a frame, the improvement including the frame as substantially described herein. Finally it should be appreciated that the present invention encompasses the use of the frames as substantially described herein in the separation of materials on a shaker separator. 
     While the apparatus, compositions and methods disclosed above have been described in terms of preferred or illustrative embodiments, it will be apparent to those of skill in the art that variations may be applied to the process described herein without departing from the concept and scope of the claimed subject matter. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the subject matter as it is set out in the following claims.