Abstract:
An apparatus for sorting particles of a material such as concrete. The apparatus includes a frame and a drive assembly attached to the frame to induce gyroscopic vibratory motion of the frame in a selected rotational direction. Adjacent first and second inclined screens are affixed to the frame. The screens slope downwardly away from an intermediate ridge at different, respective first and second angles. Material dropped onto the intermediate ridge separates into a first stream which passes along the first inclined screen and a second stream which passes along the second inclined screen. The first and second angles are selected in relation to the vibratory motion of the frame so that the first and second streams each move at substantially the same velocity. A diverter member at the intermediate ridge aids in the transition of material flow along the respective screens.

Description:
RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/302,324, filed Jun. 28, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to the field of material sorting devices, and more particularly, but not by way of limitation, to an apparatus which sorts particles of a material by motorized vibration of a pair of inclined screens.  
         BACKGROUND  
         [0003]    Sorting equipment of the type intended for sorting and separating particles of a material (also sometimes referred to as a “shaker table”) usually include a stand, a frame movably suspended on the stand, an inclined elongated screen of usually approximately four to eight feet mounted on the frame, and one or more motors mounted on the frame for vibrating the frame and attached screen. The screen has a number of apertures of selected size (such as ½ inch).  
           [0004]    A material is deposited on the upper end of the inclined vibrating screen. As the material is advanced down the screen by the vibratory motion thereof, smaller particles having diameters less than the size of the screen apertures fall through the screen while larger particles having diameters greater than screen apertures pass along the length of the screen.  
           [0005]    Such equipment finds broad application in a number of industrial areas. For example, an aggregate of granulated cement material can be processed so that smaller, useful particles are passed on for subsequent use and larger “clumps” (formed from the undesired addition of water to the aggregate) are discarded.  
           [0006]    Although such sorting systems perform their intended functions well, it has become apparent in many applications that a single screen is inefficient and as well as poorly suited to situations with clearance or topography restrictions.  
           [0007]    Thus, there is a need for improvements in the art directed to the sorting of particles of a material that overcomes these and other limitations of the prior art.  
         SUMMARY OF THE INVENTION  
         [0008]    As embodied herein and as claimed below, the present invention is generally directed to an apparatus for sorting particles of a material, such as granulated cement.  
           [0009]    In accordance with preferred embodiments, the apparatus includes a frame and a drive assembly attached to the frame to induce gyroscopic vibratory motion of the frame in a selected rotational direction. Adjacent first and second inclined screens are affixed to the frame.  
           [0010]    The screens slope downwardly away from an intermediate ridge at different, respective first and second angles. Material dropped onto the intermediate ridge separates into a first stream which passes along the first inclined screen and a second stream which passes along the second inclined screen.  
           [0011]    The first and second angles are selected in relation to the vibratory motion of the frame so that the first and second streams each move at substantially the same velocity.  
           [0012]    Preferably, the screens each comprise a plurality of screen apertures of selected size so that particles in the material smaller than the selected size pass through the apertures while particles larger than the selected size traverse the length of the screens. A diverter member at the intermediate ridge preferably aids in the transition of material flow along the respective screens.  
           [0013]    These and various other features and advantages of the claimed invention will be apparent from a reading of the following detailed description and a review of the associated drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a perspective view of a dual-screen particle sorting apparatus constructed and operated in accordance with preferred embodiments of the present invention.  
         [0015]    [0015]FIG. 2 is a partial cross-sectional view of the apparatus of FIG. 1.  
         [0016]    [0016]FIG. 3 is a partial cross-sectional side view of a frame apparatus.  
         [0017]    [0017]FIG. 4 is a partial cross-sectional side view of a diverter member of the apparatus.  
         [0018]    [0018]FIG. 5 is a top view of the apparatus.  
         [0019]    [0019]FIG. 6 is a partial cross-sectional view of a drive assembly of the apparatus. 
     
    
     DETAILED DESCRIPTION  
       [0020]    Referring to the drawings in general, and more particularly to FIG. 1, shown therein is a view of a dual-screen particle sorting apparatus  10  (herein also referred to as the “apparatus” and “dual-screen sorter”) constructed in accordance with preferred embodiments of the present invention.  
         [0021]    The dual-screen sorter  10  receives material  12  from a silo  14  that can come from a source  16 , such as a bulk storage facility. The material  12  is separated and passed on to a carrier  18  to be used on site or transported to another location. The dual-screen sorter  10  includes a frame  20  held in a stand  22 , a plurality of suspension assemblies  24 , a vibrator motor  26 , a pair of screens  28   a ,  28   b  and a diverter member  30 .  
         [0022]    In a preferred embodiment the material comprises granulated cement. Due to the undesired adsorption of water or other liquids during transit or storage, “clumps” of cement may be formed within the material. Thus as described below, the dual-screen sorter  10  operates to screen, or filter out such clumps that are larger than an acceptable size as determined by the apertures through the screens  28   a ,  28   b  (such as ½ inch diameter). The particular configuration of the dual-screen sorter  10  allows the sorter to be located in the relatively restrictive clearance space between the silo  14  and the carrier vehicle  18 .  
         [0023]    The stand  22  includes a generally rectangular-shaped base portion  32  and upright portions  34  shown in FIG. 2. The frame  20  is generally rectangular-shaped and is movably suspended on the stand by the plurality of suspension assemblies  24 . More specifically, each suspension assembly  24  includes a bottom spring pad  36  and a top spring pad  38  mounted on the frame  20  and vertically aligned with spring pad  36 . A coil spring  40  is captured between each aligned pair of spring pads  36 ,  38  for movably suspending the frame  20  on the stand  22 . The dual-screen sorter  10  has a lid  42  with an opening capable of accepting the nozzle of the silo  14  or other material carrier, such as a conveyor.  
         [0024]    [0024]FIG. 3 shows a partial cross-section of the side of the frame  20  without the drive assembly or stand  22  to make the frame  20  easier to see. The frame has a frame top  44 , body  46  and bottom  48 . The screens  28   a ,  28   b  of this embodiment are suitable for dry sorting operations and have more than one screen or screen face. The screens,  28   a ,  28   b  are removably mounted on the frame body  46  and supported within the frame  20 . The screens  28   a ,  28   b  of this embodiment are pretensioned framed screens, although other types of screens can be used if desired. The screens  28   a ,  28   b  in this embodiment are each approximately four feet in length and four feet wide and are slightly arched (approximately 3 degrees) to improve sorting efficiency. Also shown in FIG. 3 is a drive shaft  50  in the shaft opening  52 .  
         [0025]    [0025]FIG. 4 shows the diverter device  30  which includes an upper support structure  54  suspended from the frame top  44  that supports deflector supports  56  and an arcuate deflector  60 . The diverter device  30  is located below a nozzle  58 . The arcuate deflector  60  is mounted on the frame  20  by the deflector supports  56  that are supported by the upper support  54  as shown in partial cross-section. The inlet opening in this embodiment, which is directly below the nozzle  58 , is circular with a radius of about 4 feet cut in the lid  42  of the dual-screen sorter  10 . The arcuate deflector  60  is sized to allow the maximum expected particle size, specific to the application, to pass into the dual-screen sorter  10  through the space between the arcuate deflector  60  and the circumference of the opening.  
         [0026]    The arcuate deflector  60  also is built to have a specific shape with a specific camber to maximize the sorting efficiencies. In this embodiment the arcuate deflector is angled to transition from an approximate vertical direction to a direction that approximates the slope of the screens  28   a ,  28   b . The size and camber of the arcuate deflector  60  is preferably selected to achieve efficient and cost effective sorting on the dual-screen sorter  10 , and to minimize velocity reductions in the material as the material transitions from a vertical drop path to inclined travel across and through the screens  28   a ,  28   b.    
         [0027]    [0027]FIG. 5 shows a top view of the frame  20  showing the suspension assemblies  24  and the inlet opening  62  that will be cut in the lid  42 . Also shown is the upper support  54  of the diverter device  30 , which supports the arcuate deflector  60  in the position that allows the dual-screen sorter  10  to operate efficiently.  
         [0028]    The drive assembly is shown in FIG. 6. The motor (not shown) is mounted on a motor base, which in turn is attached to the frame  20 , so that the drive shaft  50  of the motor is positioned horizontally, and extends transversely with respect to the frame  20 . The motor  26  is of the type, which is well known in the sorting equipment art, and transmits a gyroscopic, generally horizontal vibrating motion to the frame through the motor base and the frame  20 . An example of a suitable motor which could be used with the dual-screen sorter  10  is the rotary electric vibrator motor manufactured by SMICO, Inc. of Oklahoma City, Okla., and identified as Model DH.  
         [0029]    Surrounding the drive shaft  50  is a shaft housing  64  and on one end of the drive shaft  50  is a counter weight  66  that helps produce the elliptical motion that drives the screens  28   a ,  28   b . The drive shaft  50  is connected to the frame body  46  by a drive hub  68 . The drive hub  68  transmits the motion created by the motor  26  from the drive shaft  50  on to the frame  20 , the screens  28   a ,  28   b , and eventually the material  12 . This transferred motion when coupled with the screen slope, mesh size, motor means and material velocity profile results in the desired material separation for a particular application. As is well known in the art, appropriate dampening devices are used to dampen harmonics caused by the dual-screen device when it operates.  
         [0030]    The improved method of the present invention for sorting and separating particles of a material using the dual-screen sorter  10  is set forth below. The motor is actuated and transmits an elliptical gyroscopic motion to the frame and attached screens.  
         [0031]    The material  12  to be processed, such as dry cement, is supplied via the nozzle  58  to the inlet opening  62  of the dual-screen sorter  10 , passing over the diverter device  30 . The cement material  12  travels over the arcuate deflector  60  and passes onto the upper ends of vibrating screens  28   a ,  28   b . The cement material  12  then travels downwardly on the screens  28   a ,  28   b  with undesirable larger size particles remaining on the screens and dropping off the lower ends of the screens  28   a ,  28   b  for removal. Although not shown with particularity in the drawings, the larger undesired particles are passed down a conduit to a suitable receptacle (such as a dumpster or bin). The desirable smaller size particles pass downwardly through screens  28   a ,  28   b  and out of the dual-screen sorter  10  into the carrier  18 .  
         [0032]    Due to the elliptical motion imparted by the motor, the resulting vibrations will tend to advance the material  12  down one of the screens  28   a ,  28   b  and tend to impede the material flow down the other screen. If the drive mechanism is moving in essentially a clockwise direction, as in this embodiment, the screens  28   a ,  28   b  that moves with the flow will be at approximately a 6-degree angle since the material  12  will flow faster down screens  28   a ,  28   b . Screens  28   a ,  28   b  will be set at approximately a 10-degree angle since the material will flow at a slower rate down screens  28   a ,  28   b . The screen angles improve the efficiency of the particle sorting operation by providing more uniform material flow. In the current embodiment the screens  28   a ,  28   b  are bolted at the desired position and are re-bolted at a new angle to change the screen&#39;s angle as desired.  
         [0033]    It should be noted that depending on the material being sized and separated, the necessary slope of the screens  28   a ,  28   b  is within the wide range from near three degrees to about sixty degrees. When it is desired to utilize particle dual-screen sorter  10  in a different application requiring a different screen slope, different bolting arrangements are used.  
         [0034]    It will be clear that the present invention is well adapted to attain the ends and advantages mentioned as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the invention disclosed and as defined.