Patent Publication Number: US-6708828-B2

Title: Magnetically fastenable magnetic wedge separator

Description:
REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/341,216 filed Dec. 20, 2001. 
    
    
     TECHNICAL FIELD 
     This invention relates to magnetic removal of ferrous metal objects from non-ferrous material. 
     BACKGROUND 
     Conveyors are used to transport various materials. As one example, a vibratory or “shaker” conveyor may transport non-ferrous material such as wood chips. The non-ferrous material may be commingled with ferrous metal objects (e.g. screws, nuts, broken machinery parts, spikes, nails, steel filings, steel chips, etc.), which if not separated from the non-ferrous material could be ingested into other processing machinery, potentially damaging the machinery. Screens provided in a shaker conveyor may not be adequate to remove such ferrous metal objects. This invention assists in removal of such ferrous metal objects. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is an oblique perspective view of a magnetically fastenable magnetic wedge separator in accordance with the invention. 
     FIG. 2 is a top plan view of the FIG. 1 apparatus. 
     FIG. 3 is a cross-sectional side elevation view of the FIG. 1 apparatus in operation on a shaker conveyor. 
    
    
     DESCRIPTION 
     Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
     The invention provides a wedge-shaped separator  10  having a leading edge  12  and a trailing edge  14 . One or more fastening magnets  16  are embedded within separator  10  to removably magnetically fasten separator  10  atop the ferrous metal surface  18  of a conveyor such as a shaker conveyor, without the need for structural modification or adaptation of the conveyor to receive or retain separator  10 . The body of separator  10  is preferably a non-ferrous material such as polyurethane formed in a wedge shape to provide an inclined surface  19  extending upwardly from leading edge  12  to trailing edge  14 . Protective caps  20 ,  22  can be fitted over leading edge  12  and trailing edge  14  respectively. One or more separating magnets  24  are embedded within separator  10 , adjacent trailing edge  14 . Trailing edge cap  22  is made of a non-ferrous material to minimize interference with the magnetic field  32  of separating magnets  24 . 
     Conveyor surface  18  transports a moving stream of non-ferrous material  26  (e.g. wood chips) in the direction indicated by arrow  28  (i.e. from right to left as viewed in FIG.  3 ). Non-ferrous material  26  may be commingled with some ferrous metal objects  30  (e.g. screws, nuts, broken machinery parts, spikes, nails, steel filings, steel chips, etc.). 
     Commingled non-ferrous material  26  and ferrous metal objects  30  are transported along conveyor surface  18 , initially encountering separator  10 &#39;s leading edge  12  which diverts commingled non-ferrous material  26  and ferrous metal objects  30  from conveyor surface  18  onto separator  10 &#39;s inclined surface  19 . Separator  10  is formed such that its width dimension “W” (FIG. 2) in only slightly smaller than the width of conveyor surface  18 , so that substantially all material transported along conveyor surface  18  will be diverted onto separator  10 &#39;s inclined surface  19 . The shaker conveyor&#39;s vibratory (shaking) action transports the diverted commingled non-ferrous material  26  and ferrous metal objects  30  across inclined surface  19 , toward and over trailing edge  14  which abruptly intersects conveyor surface  18 . 
     Commingled non-ferrous material  26  and ferrous metal objects  30  encounter the magnetic field  32  of separating magnets  24  as the commingled material and objects are transported over trailing edge  14 . Depending upon their size, substantially all ferrous metal objects  30  are magnetically attracted toward separating magnets  24  and magnetically retained on separator  10  near trailing edge  14 ; without substantially impeding transport of non-ferrous material  26  along the conveyor. More particularly, non-ferrous material  26  is unaffected by separating magnets  24 , drops off trailing edge  14  onto conveyor surface  18 , and is transported along conveyor surface  18  away from separator  10  in the direction of arrow  28  for further processing (not shown). Periodically, at convenient times, any ferrous metal objects  30  magnetically retained on separator  10  can be removed, for example by scraping such objects off separator  10  with a non-metallic scraping tool (not shown). 
     Instead of using fastening magnets  16  to removably magnetically retain separator  10  atop conveyor surface  18 , metal backing plates can be embedded in separator  10  to facilitate welding, bolting, clamping or other attachment of separator  10  to the conveyor. This may however require structural modification or adaptation of the conveyor to receive or retain separator  10 . Besides avoiding conveyor modification or adaptation to receive or retain separator  10 , fastening magnets  16  allow rapid removal and replacement of separator  10 . Specifically, the tip of a pry bar—not shown—can be inserted into one of leading edge recesses  34  (or into another recess—not shown—in trailing edge  14 ) and force can then be applied to the pry bar to break the magnetic bond between separator  10  and conveyor surface  18 . Other techniques known to persons skilled in the art, such as use of a jacking bolt—not shown—can be employed to break the magnetic bond between separator  10  and conveyor surface  18 . The capability to rapidly remove separator  10  from the conveyor also simplifies removal of ferrous metal objects  30  magnetically retained on separator  10 , after which separator  10  can be quickly returned to service on the conveyor. Fastening magnets  16  also allow separator  10  to be rapidly removed from one conveyor and placed in service on a different conveyor. 
     Fastening magnets  16  further allow separator  10  to be rapidly removed from one location on a particular conveyor and replaced in service at a different location on the same conveyor. This enables optimization of separator  10 &#39;s capability to remove ferrous metal objects  30  from non-ferrous material  26 , which may be affected by factors such as the particular type of non-ferrous material being conveyed; and, the size, volume or consistency of ferrous metal objects  30  typically commingled within non-ferrous material  26 .