Abstract:
The present invention provides a screen for separating materials according to particle size. The screen has a body, a plurality of fingers, and a plurality of rods. The fingers may be integrally formed with the body. The rods are supported within the body and extend within the fingers to provide structural stability.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application No. 60/785,497, entitled “Cantilever Rod Screen” filed on Mar. 24, 2006, which is hereby incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to a screen for separating materials and, more particularly, to a cantilever rod screen and method of making the same.  
       BACKGROUND OF THE INVENTION  
       [0003]     Vibrating screen machines are used to separate aggregate particles such as topsoil, rock, crushed rock, gravel, sand, landfill material, recycling waste, compost, demolition debris, and the like (herein collectively referred to as “material”) into various sizes. These machines typically comprise one or more screens containing perforated plates, molded plastic with holes, wire cloth screens, or a plurality of evenly spaced fingers, which together act as a sieve through which the material is separated. In screens with a plurality of fingers, a charge of material typically is deposited on the receiving end of the screen and, as the machine vibrates, the fingers vibrate, conveying the material across the fingers to the discharge end. As the material is conveyed across the fingers, smaller material falls through the openings, allowing the larger material to continue across the fingers to a location separate from the smaller particles. Accordingly, the fingers must be strong enough to support the weight of the material, yet flexible enough to withstand vibration.  
         [0004]     Most screens have rod-like metallic fingers that are individually bolted or welded to a support bracket, or clamped in a flexible clamp block to withstand vibrations. However, such screens have numerous parts and require extensive assembly time, making them expensive to manufacture and install. In addition, fingers that are rigidly attached by bolts and welds are subject to mechanical failure at their point of attachment, while clamped fingers may loosen during operation.  
         [0005]     These fingers are also susceptible to abrasion and lodging of material between the fingers, which produces bowing and spacing between the fingers, resulting in poor screening. Attempts have been made to protect the metallic fingers by coating them with a thin layer of wear-resistant material. However, such coatings do not provide a sufficient volume of wear material to adequately protect the fingers during use. Alternatively, fingers made exclusively of flexible, wear-resistant material do not provide sufficient stiffness to satisfactorily separate materials. Therefore, it is desired to provide an inexpensive screen with fewer parts that eliminates the typical stress points and avoids loosening during operation. It is also desired to provide a screen having both increased wear-resistance and sufficient stiffness for separating materials according to particle size.  
         [0006]     Additional information will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention relates to a screen for separating materials according to particle size. The screen has a body, a plurality of fingers, and a plurality of rods. The fingers may be integrally formed with the body. The rods may have a first end supported within the body and a second end extending within the fingers to provide structural stability.  
         [0008]     In another aspect, the present invention is directed to a method for producing a screen that comprises providing a mold having a cavity, positioning a plurality of rods in the cavity, inserting a material to substantially fill the cavity, and molding a screen having a body and a plurality of fingers integrally formed with and extending from the body, so that the first end of each rod is supported within the body and the second end of each rod extends within the fingers to provide structural stability. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0009]     Operation of the invention may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein:  
         [0010]      FIG. 1  is a perspective view of a cantilever rod screen in an embodiment of the invention.  
         [0011]      FIG. 2  is a side view of the screen of  FIG. 1 .  
         [0012]      FIG. 3  is a cross-sectional view of a screen finger in an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     While the present invention is described with reference to the embodiments described herein, it should be clear that the present invention should not be limited to such embodiments. Therefore, the description of the embodiments herein is merely illustrative of the present invention and should not limit the scope of the invention as claimed.  
         [0014]     Reference will now be made in detail to the embodiments of the invention as illustrated in the accompanying figures. Embodiments of a cantilever rod screen  10  are shown in  FIGS. 1 through 3 . The screen  10  generally has a body  12  with a plurality of fingers  14  and a plurality of rods  16 .  
         [0015]     As shown in  FIG. 1 , the body  12  may have an elongated, substantially trapezoidal or wedge-shape, with a face  18  located at an opposing end of a rear wall  20 . As best shown in  FIG. 2 , the perimeter of the body  12  leading from the rear wall  20  to the face  18  may be tapered to facilitate installation in a fixture  22  of a vibrating screen machine. The body  12  may be fabricated from any known material having flexible and wear-resistant properties. Typically, the body  12  may be fabricated from a polymeric material, such as polyurethane or rubber. However, the body  12  should not be deemed as limited to any specific shape or material. One of ordinary skill in the art will appreciate the use of various shapes and materials for the body  12 .  
         [0016]     The fingers  14  are attached to the body  12  and are capable of freely vibrating. In one embodiment, the fingers  14  may be integrally formed with the body  12 . As shown in  FIG. 1 , the fingers  14  may be substantially rectangular in shape and composed of the same flexible, wear-resistant material as the body  12 . As best shown in  FIG. 1 , the fingers  14  may be arranged substantially parallel to each other in a substantially coplanar row extending substantially perpendicularly outward from the face  18 . Accordingly, the row of fingers  14  defines an array of sieve-like openings  24  of a predetermined size for allowing material of up to a predetermined size to pass through the fingers  14 .  
         [0017]     As best shown in  FIG. 2 , the rods  16  have a first end  26  embedded and/or molded in the body  12  and a second end  28  extending outwardly from the face  18  and through the fingers  14 . The rods  16  support the fingers  14  to provide sufficient stiffness for material separation. As best shown in  FIG. 3 , the rods may be embedded within the fingers  14  by a molding process, and may extend the length of the fingers  14 . The rods  16  may be composed of metals, polymers, combinations or composites thereof, or other suitable materials. In addition, although illustrated as cylindrical in shape, the rods  16  should not be deemed as limited to any specific shape. One of ordinary skill in the art will appreciate the use of various shapes for the rods  16 .  
         [0018]     Turning to the screen  10 , an example of how to use the screen  10  as illustrated in  FIGS. 1-3  is set forth below. As shown in  FIG. 2 , the body  12  is positioned in a fixture cavity  22  of a vibrating screen machine. When in place, the machine may begin vibrating and particulate material may be fed to the screen  10 . The free vibration of the wear-resistant fingers  14  may separate any agglomeration or stratification of the material and may provide an improved self-cleaning action that prevents the clogging of the fingers  14  typically occuring in conventional screens. The vibrating action of the fingers may induce lateral movement of the material, wherein smaller material falls through the sieve-like openings  24  while larger material is retained by the fingers  14 .  
         [0019]     Screens as described herein may be produced in a variety of manners. For example, they may be formed or manufactured by any molding or casting process. Non-limiting, illustrative examples of molding processes include injection, compression, transfer, and reaction injection molding. The mold typically includes a cavity that generally defines the shape of the above-described screen  10 . Rods  16  may be positioned in the mold, and a polymeric material may then be inserted into the cavity. Once the screen  10  is formed, the screen  10  can be removed from the mold.  
         [0020]     As can be understood from the above description, the screen  10  allows for easy installation and replacement in a vibrating screen machine. The screen  10  can be inexpensively molded, thereby reducing equipment costs. If one or more fingers  14  suffer mechanical failure, the entire screen  10  can be quickly replaced, thereby reducing downtime. Moreover, the individual fingers  14  may not require removal or replacement, resulting in significant labor savings. In addition, the rods  16  may be embedded in a resilient manner in the body  12  by a molding or casting process, reducing or eliminating stress points at which mechanical failure of the rods  16  and fingers  14  occur.  
         [0021]     The invention has been described above and, obviously, modifications and alternations will occur to others upon a reading and understanding of this specification. The claims as follows are intended to include all modifications and alterations insofar as they come within the scope of the claims or the equivalent thereof.