Abstract:
A grate magnet apparatus comprising a frame defining an opening adapted to have material to be separated pass therethrough, a non-magnetic tube supported by the frame and extending across the opening, and an elongated magnetic member removably housed in the tube, whereby magnetic material is attracted to the tube when the magnetic member is housed in the tube and is released from the tube when the member is removed from the tube. The non-magnetic tubes and magnet members are connected both for joint movement to be withdrawn from the path of the flowing material and then for relative movement to release magnetic material from the non-magnetic tube.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to magnetic separation devices and, more particularly, to grate magnets. 
     A conventional grate magnet includes a frame defining an opening through which material to be separated passes. A plurality of elongated, usually cylindrical magnets extend across the opening so that magnetic material is attracted to the magnets while non-magnetic material is not. Typically, the magnets are mounted in a drawer-like frame that is slidably housed in a delivery duct or chute so that the magnets can be removed from the duct before magnetic material is removed from the magnets. Removal of magnetic material from the magnets can be difficult. 
     SUMMARY OF THE INVENTION 
     The invention provides a grate magnet apparatus in which the magnets of the prior art are replaced by non-magnetic tubes slidably housing elongated magnets. When the magnets are in the tubes, magnetic material is attracted to the exterior of the tubes. When the magnets are removed from the tubes, the magnetic material falls off the exterior of the tubes. 
     More particularly, the preferred embodiment of the invention is combined with a duct defining an opening into a chamber adapted to contain non-magnetic material, and a frame defines an opening in the duct through which material to be separated passes. The frame is removably housed within the duct with the opening in the frame aligned with the opening into the chamber. The apparatus also comprises a plurality, e.g. ten or twelve, of parallel, non-magnetic tubes supported by the frame and extending across the opening in the frame. Each of the tubes removably houses a respective elongated, cylindrical magnet. 
     As described above, the magnets can be pulled out of the tubes in order to remove magnetic material from the exterior of the tubes. In order to facilitate removal of the magnets from the tubes, the magnets are connected together so that they can be removed from their respective tubes simultaneously. This could present a problem in that, because it could be difficult to line up ten or more magnets with their respective tubes, and because the magnets are relatively heavy, it could be difficult to align all of the magnets with the ends of their respective tubes in order to reinsert the magnets into the tubes. 
     In order to eliminate this potential problem, the magnets are maintained in alignment with their respective tubes, preferably by having the tubes extend beyond the frame. In other words, each tube includes a first portion extending across the opening through which material passes, and a second portion extending beyond or outside of the opening. Preferably, the frame includes a wall which partially defines the opening in the frame, the first portion of each tube extends on one side of the wall, and the second portion of each tube extends on the other side of the wall. Since only the first portions of the tubes extend across the opening, magnetic material is attracted only to the first portions when the magnets are housed in the tubes. Therefore, it is only necessary to remove the magnets from the first portions of the tubes in order to remove magnetic material from the tubes. The ends of the magnets can remain housed in the second portions of the tubes while magnetic material is removed from the first portions, and the second portions of the tubes therefore maintain alignment of the magnets with the tubes and guide the magnets back into the tubes after magnetic material is removed from the first portions of the tubes. 
     When the magnets are withdrawn from the first portions of the tubes, magnetic material on the exterior of the tubes tends to follow the magnets toward the frame wall separating the first portions from the second portions. The frame wall separating the first and second tube portions acts as a scraper and causes magnetic material to fall off the exterior of the tubes when it hits the frame wall and the magnets are fully withdrawn from the first portions of the tubes. 
     In the preferred embodiment, the outer ends of the magnets are interconnected by a plate having thereon a handle for facilitating manual movement of the magnets. Preferably, a chain extends between the frame and the plate to prevent the magnets from being completely withdrawn from the tubes, i.e., from being pulled out of the second portions of the tubes. 
    
    
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial, side elevational view of a grate magnet apparatus embodying the invention and comprising a duct, a frame slidably houses in the duct, a plurality of tubes supported by the frame, and a plurality of cylindrical magnets slidably housed by the tubes. 
     FIG. 2 is a view similar to FIG. 1 and showing the frame removed from the housing. 
     FIG. 3 is a view similar to FIG. 2 and showing the magnets removed from the tubes. 
     FIG. 4 is a top view of the apparatus. 
     FIG. 5 is a view taken along line 5--5 in FIG. 2. 
     FIG. 6 is a top view of the frame and showing the magnets partially removed from the tubes. 
     FIG. 7 is an enlarged, partial top view of the frame, a tube, and a magnet being withdrawn from the tube. 
    
    
     Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention iscapable of other embodiments and of being practiced or being carried out invarious ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A grate magnet apparatus 10 embodying the invention is illustrated in the drawings. As shown in FIGS. 1 and 4, the apparatus 10 comprises a generally rectangular duct 12 defining an opening 14 into a chamber 16 adapted to contain non-magnetic material. The chamber 16 can be enclosed within the duct 12 or can simply communicate with a container (not shown) for non-magnetic material. As shown in FIG. 4, the duct 12 includes two pairs of generally perpendicular walls 18, 20, 22 and 24. The wall 18 of the duct 12 has therein a rectangular opening 26 (see FIG. 1). 
     The apparatus 10 also comprises a generally rectangular, drawer-like frame 28. As best shown in FIG. 6, the frame 28 includes two pairs of generally perpendicular walls 30, 32, 34 and 36 and defines an opening 38 through which material intended to undergo the separation process passes. The frame 28 extends through the opening 26 in the duct wall 18 and is slidably and removably housed by the duct 12 with the opening 38 in the frame 28 aligned with the opening 14 in the duct 12, so that material passing through the opening 14 in the duct 12 also passes through the opening 38 in the frame 28 and into the chamber 16. When the frame 28 is pulled out of the duct 12, as shown in FIGS. 2 and 3, the frame opening 38does not overlap with the duct opening 14. 
     A plurality of generally parallel tubes 40 are supported by the frame 28 and extend across the frame opening 38. These tubes are made of a non-magnetic material such as stainless steel. Preferably, the tubes 40 extend through the frame wall 30 and each tube 40 includes a first portion42 extending on one side of the frame wall 30 and across the frame opening 38, and a second portion 44 extending on the other side of the frame wall 30 and thus beyond the frame opening 38. 
     Each tube 40 removably houses a respective elongated, cylindrical magnetic member or magnet 46. When the members 46 are fully inserted into the tubes40 and the frame 28 is fully inserted into the duct 12, magnetic material passing through the duct 12 is attracted only to the exterior of the firstportions 42 of the tubes 40. When the members 46 are removed from the tubes40, i.e., at least from the first portions 42 of the tubes 40, magnetic material is released from the exterior of the tubes 40. 
     Means 48 connnects the members 46 for common movement of the members 46 axially of the tubes 40 in response to movement of the connecting means 48. While various suitable connecting means 48 can be employed, in the preferred embodiment, the connecting means 48 includes a plate 50 fixedly connected to the ends of the members 46. As illustrated in the drawings, the plate 50 has thereon a handle 52 for facilitating manual movement of the members 46. 
     Means 54 maintains alignment of the members 46 with the tubes 40 and guidesthe members 46 into the tubes 40 after the members 46 are withdrawn from the tubes 40, i.e., from the first Portions 42 of the tubes 40. While various suitable aligning and guiding means 54 can be used, in the illustrated construction, such means 54 includes the second portions 44 ofthe tubes 40. As explained above, magnetic material is attracted only to the first portions 42 of the tubes 40 when the magnets or members 46 are fully inserted into the tubes 40. Therefore, it is only necessary to withdraw the magnets 46 from the first portions 42 of the tubes 40 in order to remove magnetic material from the exterior of the tubes 40. Accordingly, the ends of the magnets 46 can remain housed in the second portions 44 of the tubes 40, as shown in FIG. 3, so that the magnets 46 remain aligned with their respective tubes 40. 
     In the preferred embodiment, means 56 is also provided for preventing removal of the magnets 46 from the second portions 44 of the tubes 40. While various suitable preventing means 56 can be employed, in the preferred embodiment, such means 56 includes a chain 58 extending between the frame 28 and the plate 50. The length of chain 58 is such that it prevents complete withdrawal of magnets 46 from portions 44. 
     Preferably, means 60 is provided for locking the frame 28 within the duct 12, i.e., in the position shown in FIGS. 1 and 4. While various suitable locking means can be employed, in the preferred embodiment, such means 60 includes a member 62 (see FIG. 1) which is pivotally mounted on the wall 18 of the duct 12 by a bolt 64 and which is pivotally movable between a locked position (shown in solid lines in FIG. 1) wherein the member 62 overlaps the frame 28 and prevents withdrawal of the frame 28 from the duct 12 and an unlocked position (shown in dotted lines in FIG. 1) whereinthe member 62 permits withdrawal of the frame 28 from the duct 12. 
     Means 70 is also provided for securing the plate 50 to the frame 28 so thatthe entire assembly of the plate 50, the frame 28, the tubes 40 and the magnetic members 46 can be withdrawn from the duct 12 by pulling on the handle 52. While various suitable means can be used, in the illustrated construction, such means 70 includes a pair of studs 72 extending outwardly from the frame wall 30 and through aligned apertures (not shown)in the plate 50. The means 70 also includes wing nuts 74 removably threadedonto the studs 72. When the members 46 are fully inserted into the tubes 40, the studs extend through the apertures in the plate 50, and the wing nuts 74 are threaded onto the studs 72 to prevent movement of the plate 50relative to the frame 28. When the handle 52 is pulled away from the duct 12 with the wing nuts 74 threaded onto the studs 72, the frame 28 is withdrawn from the duct 12. After the wing nuts 74 are removed from the studs 72, pulling on the handle 52 causes the plate 50 to move away from the frame 28 and withdraws the members 46 from the tubes 40. 
     The apparatus operates as follows. When the frame 28 is fully housed in theduct 12 and the magnets 46 are fully housed in the tubes 40, as shown in FIG. 1, material passing through the duct 12 passes over the exterior of the first portions 42 of the tubes 40. Magnetic material is attracted to the exterior of the first portions 42 of the tubes 40, while non-magnetic material is allowed to pass into the chamber 16. In order to remove magnetic material from the exterior of the tubes 40, the frame 28 is firstremoved from the duct 12, as shown in FIG. 2. Next, the magnets 46 are withdrawn from the first portions 42 of the tubes 40, as shown in FIG. 3. 
     As can be seen in the drawings, the movement of the frame relative to the duct and then the movement of the magnets relative to the frame is in the same direction along the same path of movement relative to the duct. As the magnets 46 are withdrawn from the tubes 40, as shown in FIG. 7, magnetic material on the exterior of the tubes 40 follows the magnets 46 along the exterior of the tubes 40. The frame wall 30 acts as a scraper and a barrier preventing the magnetic material from following the magnets 46 and causing the magnetic material to fall off the exterior of the tubes40. Any magnetic material remaining on the exterior of the tubes 40 can be easily brushed off, since it is not magnetically attracted to the tubes 40. 
     Various features of the invention are set forth in the following claims.