Abstract:
A vibrating screen apparatus for sizing materials is shown that has a minimum of moving parts therein. A vibrating motor is mounted below longitudinal vibrating bars. The vibrating bars are set on air mounts, which air mounts are between the vibrating bars and cross braces connected to the frame. The vibrating bars press against the underside of a vibrating screen to form a crown therein when the air mounts are inflated. The vibrating screen is stretched between the sides of the frame by tensioning rails. A shroud over the top of the frame is secured in place. Multiple size materials can be produced by stacking multiple vibrating screen apparatuses.

Description:
This application is a continuation-in-part of application Ser. No. 09/320,033, filed on May 26, 1999, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vibrating screen mechanism and, more particularly, to a vibrating screen mechanism that is used to separate materials by size. 
     2. Background of the Invention 
     For many years, vibrating screens have been used to separate products into different sizes. While some screens may be used in an environment that is relatively mild, other screens would be used in the harshest of environments, such as mines, quarries or plants, where materials, such a bauxite, gravel, crushed rock, limestone, cement, shale or clay, are sized into different sizes. In these harsh environments in which a vibrating screen operates, any mechanically moving parts can be fouled by dust, grit or grime from the materials being sized. The larger number of moving parts to operate the vibrating screen, the greater the probability there will be a mechanical failure. The simpler the operation of the vibrating screen, the less likely the mechanical parts will foul or break. 
     U.S. Pat. No. 4,444,656 to Nelson shows a vibrating screen with a plurality of transverse beams extending from side to side for vibrating the screen. A large number of beams are used, as well as a large number of moving parts. Likewise, a plurality of different motors are used, with each transverse beam having a different motor and a different rate of vibration. 
     Typical of the modern day vibrating screen are those screens disclosed in U.S. Pat. Nos. 3,378,142; 3,834,534; 4,180,458; 4,274,953; 4,340,469; 4,632,751; 5,100,539; 5,341,939; and 5,749,471. Unlike the present invention, in each of the referenced patents, a motor is attached to a frame to which is attached a screen. Activation of the motor causes the frame and consequently, the screen to vibrate. To allow such vibration, the frame is somehow affixed to isolating devices, usually springs. U.S. Pat. No. 3,378,142 imparts the vibrating force to the frame using “two drivingly coupled resiliently borne oscillating frames having alternative inter-engaging cross members.” U.S. Pat. No. 3,834,534 attaches a screen to a frame using springs and then allows the vibration mode of the screen and frame assembly to be controlled as well as slid beneath the screen. U.S. Pat. No. 4,180,458 uses a traditional structure, but isolates the structure to achieve better noise control. U.S. Pat. No. 4,274,953 mounts the vibration motor on the outside of the frame. U.S. Pat. No. 4,340,469 imparts the vibrational force to the frame and screen using unbalanced weights to generate gyrational vibratory motion. U.S. Pat. Nos. 4,632,751; 5,100,539; 5,341,939; and 5,749,471 each contain disclosures typical of vibrating frame/screens. Unlike the present invention, all of the inventions disclosed in the foregoing patents contain complex vibrating mechanisms with multiple mechanical parts and the vibrating force is imparted to a frame which in turn causes the screen to vibrate. 
     Not known to be the subject of a U.S. patent, is the vibrating screen apparatus utilized by J&amp;H Equipment, Inc. (“J&amp;H”), P.O. Box 928, Roswell, Ga. 30077, telephone number (800) 989-1606. Unlike the present invention which does not attach the vibrating screen apparatus to the screen and which does not require attachment through the screen, the J&amp;H vibrating screen apparatus attaches rods across and through a screen. The rods are then attached to an overhead motor which, when activated, unlike the present invention, causes the entire apparatus, screen rods and screen to vibrate. 
     To simply and advance the prior art, a vibrating screen apparatus must, as does the present invention, reduce the number and complexity of the mechanical parts necessary to cause vibration of the screen and which in fact vibrate. Furthermore, for ease of maintenance, the entire vibrating apparatus should easily remove from the screen system. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a vibrating screen apparatus with a minimum amount of moving parts. 
     It is a further object of the present invention to provide a vibrating screen apparatus that is easily maintained and repaired. 
     It is yet another object of the present invention to provide a vibrating screen apparatus that is more reliable and economical to operate. 
     It is an even further object of the present invention to provide a vibrating screen apparatus that has less dust pollution or noise proliferation. 
     It is yet another object of the present invention to have vibrating bars that run lengthwise of the screen to impart the necessary vibrations to the screen. 
     It is yet another object of the present invention to suspend the vibrating bars and pull the screen taut by inflating air mounts below the vibrating bars. 
     It is yet another object of the present invention to provide tension rails for proper tensioning of the wire cloth that makes up the vibrating screen. 
     It is even another object of the present invention to mount the vibrating motor to the vibrating bars to cause the vibration of the wire cloth of the vibrating screen apparatus. 
     In the present invention, side plates are held into position by cross braces to form the frame of the present vibrating screen apparatus. The bottom of the frame is enclosed by a concave surface and a discharge outlet for the fine material that has gone through the last screen. 
     The screen is made of wire cloth that is tightened by tension rails on each side. The tension rails connect into hooks that are attached to the wire cloth and pulled tight between the respective sides of the frame. 
     Immediately below the screen are vibrating bars that run lengthwise of the screen. Attached to the underside of the vibrating bars is a vibrating motor that will cause the bars to vibrate. On top of the vibrating bars is some type of resilient material, such as rubber, to keep the vibrating bars from wearing out the screen. 
     The vibrating bars are mounted on air mounts set on cross braces between the sides of the frame. By inflating the air mounts, the screen is tightened to the predetermined tautness that is desired when the vibrating bar is lifted. Tension on the wire cloth increased and the vibrating mechanism is ready to be turned ON for operation. 
     Material to be sized comes in at the feed end of the vibrating screen apparatus. Material that is less than the predetermined size of the wire cloth will go through the screen and be less than the predetermined size. The remainder of the material that is larger than the predetermined size will come out of the discharge end of the vibrating screen apparatus. 
     If material is to be sized between a predetermined range, vibrating screen apparatuses can be stacked one on top of the other and material that comes out of the discharge end of other than the top vibrating screen apparatus would be of a predetermined size range depending upon the size of the individual screens therebetween. 
     To prevent air pollution by dust and other particles, a cover will cover the uppermost of the vibrating screen apparatuses. In the present invention, a rubber dust cover is used that is ratcheted down tightly into place to prevent noise proliferation or environmental pollution by dust. 
     Since the entire vibrating screen apparatus is gravity fed, the angle of the frame should be at least greater than the angle of repose of the material being sized. It is anticipated the angle of repose would typically be between 15°-45°. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a demonstration model of the present invention with a portion cut away for illustration purposes. 
     FIG. 2 is a partial perspective cutaway view of the present invention illustrating the mounting of the vibrating bar. 
     FIG. 3 is a perspective view of the frame with the vibrating bar as mounted therein. 
     FIG. 3A is a cross-sectional view of the vibrating mechanism of FIG. 2 along section lines  3 A— 3 A, with the air mounts deflated. 
     FIG. 3B is a cross-sectional view of the vibrating mechanism of FIG. 2 along section lines  3 A— 3 A, with the air mounts inflated. 
     FIG. 4 is a side view illustrating the mounting of the motor to the vibrating bar. 
     FIG. 5 is an enlarged partial sectional view illustrating positioning of the air mounts between the vibrating bar and the cross braces. 
     FIG. 6 is an enlarged partial sectional view illustrating the tensioning of the wire cloth. 
     FIG. 7 is an enlarged partial sectional view illustrating contact between the vibrating bar and the wire cloth. 
     FIG. 8 is a partial sectional view illustrating the tensioning of the wire cloth and the securing of the shroud. 
     FIG. 9 is a side view illustrating the stacking of multiple vibrating screens to give multiple size materials therefrom. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the present invention, a description of a demonstrator model of the vibrating screen apparatus  12  is shown. Material to be sized  14  feeds into the hopper  16  of the present invention. The hopper  16  may be pivoted on pivot point  18  so that the material to be sized  14  feeds out of the hopper  16  at the lower end  20  thereof into the vibrating screen body  22 . The vibrating screen body  22  has a frame  24  (shown in detail in FIG. 3) that is covered by a shroud  26 . The shroud  26  is held in position by ratcheted tie-downs  28  on the side walls  30 . 
     Inside of the vibrating screen body  22  is located a vibrating screen  32  that is typically made from a wire cloth. The vibrating screen  32  is tensioned between the respective side walls  30  by means of a tension rail  34 . 
     The angle of repose of the vibrating screen body  22  is great enough so the material be sized  14  will flow there along by gravity. The vibrating screen body  22  may be pivoted on pivot point  36  by means of hydraulic ram  38 . By extending the hydraulic ram  38 , the angle of repose can be increased. The slot  46  along with the pivot bar  48  allow for adjustment of the angle of repose between the hopper  16  and the vibrating screen body  22 . As the material to be sized  14  feeds through the vibrating screen body  22 , the larger particles  40  that will not go through the vibrating screen  32  and come out the discharge end  42 . The sized particles  44  that are smaller than the spaces in the vibrating screen  32  come out of the bottom of the vibrating screen body  22 . 
     Referring now to FIG. 2 of the drawings, an enlarged partial sectional view of the vibrating screen body  22  is shown. A portion of the shroud  26  has been cut away to illustrate the screen  32  being stretched between the sides  30  by means of tension rail  34  being tightened into position by bolts  50 . This will be explained in more detail in conjunction with FIG.  6 . 
     Immediately below the vibrating screen  32 , which is made of wire cloth, is located two parallel vibrating rails  52 . The vibrating rails  52  run lengthwise along the vibrating screen body  22  from one end thereof to the other. The vibrating rails  52  are supported on the bottom thereof by air mounts  54 . The air mounts  54  are mounted to cross braces  56  by means of a mounting platform  58 . 
     Suspended below vibrating rails  52  is a vibrating motor  60 . Vibrating motor  60  attaches directly to vibrating rails  52  by any convenient means, such as base  62 . By turning on the vibrating motor  60 , through the base  62 , it causes the vibrating rails  52  to vibrate. The vibration of the vibrating rails  52  will in turn cause the screen  32  to vibrate. By inflating the air mounts  54 , the vibrating rails  52  will be the sole contact between the screen  32 , other than the edges that are tightened into place by tension rail  34 . 
     Turning now to FIG. 3 of the drawings, the frame  24  will be explained in more detail. The side walls  30  make up the sides of the frame  24 . Across the bottom of the frame  24  are lower cross braces  64 , which can be of any dimension; however, applicant has found that circular braces do not cause an accumulation of the material being sized. 
     Towards the upper part of the side walls  30  are the upper cross braces  66 . While the upper cross braces  66  can be of any particular size, square bar stock has found to be particularly suitable for this particular application. The upper cross braces  66  connect to the side walls  30  just below the vibrating screen mount  68 . The vibrating rails  52  are secured to the top of the air mounts  54 . The air mounts  54  are secured to the frame  24  by means of mounting platform  58  on upper cross braces  66 . The vibrating motor  60  suspends below the vibrating rails  52  by means of inverted base  62 . 
     Referring now to FIGS. 3A and 3B in combination, the proper tensioning of the vibrating screen  32  is shown and explained. Referring first to the tightening of the vibrating screen  32 , enlarged FIG. 6 may be useful. The vibrating screen  32  is a wire cloth that is made with a predetermined mesh. The wire cloth has warp wires  70  that run lengthwise along the vibrating screen and shoot wires  72  that run perpendicular to the warp wire and perpendicular to the side walls  30 . For the purpose of tensioning vibrating screen  32 , some type of hook or connection is provided on the chute wires  72 . In the present case, hooks  74  are contained on the ends of the chute wires  72 . 
     To install the vibrating screen  32 , it is placed inside of the vibrating screen body  22  on the vibrating screen mount  68 . Then the hook side  76  of the tension rail  34  is placed inside of the hooks  74 . By tightening nuts  78  on bolts  50 , the slide side  80  of the tension rail  34  will slide along the side  30  and allow the tension rail  34  to tighten screen  32  by pulling against the hooks  74 . By tightening the nuts  78  on the bolts  50 , the vibrating screen  32  can be tightened to any desired tension. However, care should be exercised not to tighten too much, otherwise any bend contained in the warp wires or chute wires of the vibrating screen  32  may be deformed. 
     Again, referring to FIGS. 3A and 3B, the tightening of the shroud  26  will be explained in conjunction with enlarged cross-sectional view FIG.  8 . The ratcheted tie-downs  28  will be explained in more detail. A strap  82  is connected to the shroud  26  by any convenient means, such as bolts  84  having eyelets with hooks  86  running therethrough. The hooks  86  connect to strap  82 , which are tightened by ratchet  88 . The other side of the ratchet  88  is connected to side wall  30  by means of flange  90  and bolt  92 . 
     In FIG. 3A, the air mounts  54  are deflated and the vibrating screen  32  is in its lowermost position. However, in FIG. 3B, the air mounts  54  are inflated so the vibrating rails  52  are raised up. In that manner, the vibrating screen  32  forms a crown and only comes into contact with the vibrating rails  52 . Therefore, when the vibrating rails  52  vibrate, the screen  32  will vibrate. 
     Referring to FIG. 7, the top part of the vibrating rail  52  is shown. The uppermost portion of vibrating rail  52  is capped by a rubber grommet  94  to prevent damage to the vibrating screen  32 . Any other type of resilient material to prevent damage to vibrating screen  32  can be used. In situations where a hot material is being sized, the rubber grommet  94  can be replaced with a heat resistant flexible material or even eliminated, if necessary. 
     Referring now to FIG. 5, the mounting of the vibrating rail  52  to the air mount  54  is illustrated. The vibrating rail  52  may be connected to air mount  54  by any convenient means, such as bolt  96  and nut  98 . On the underside, the air mount  54  is connected to the mounting platform  58  by means of similar bolt  96  and nut  98 . Also, the rubber grommet  94  is illustrated on the vibrating rail  52 . 
     FIG. 4 shows the mounting of the vibrating motor  60  on the underside of the vibrating rails  52  by means of bolts  100  and nuts  102  through base  62 . The vibrating motor may be of any particular type, but applicant has found that motors made by Visam are particularly suited for the present operation because of the adjustability of their speed and vibrating weight. Also, these motors have variable frequencies and may differ in power requirements according to the needs of the particular situation. The particular Visam motor can be selected and set according to the particular requirements of the job. 
     In actual operation, the vibrating screen apparatus can be tightened to a particular tension by inflating the air mounts  54  through inflating valve  104  as shown in FIG.  1 . The inflating valve is connected by hoses (not shown) to the air mounts  54 . The pressure gauge  106  measures the amount of pressure that has been inserted in the air mount  54 . By use of the air mounts  54  and inflating them to a predetermined pressure, the tension on the vibrating screen  32  is continually adjusted. This adjustment eliminates the re-tensioning of the screen  32  or makes the re-tensioning a less frequent requirement. 
     By putting the material to be sized  14  into hopper  16  and allowing it to flow through the lower end  20  thereof into the vibrating screen body  22 , material to be sized  14  now flows along the vibrating screen body  22 . Particles that were too large to flow through the vibrating screen  32  will come out the discharge end  42  as larger particles  40 . The sized particles  44  will flow out of the bottom of the vibrating screen body  22 . 
     To size particles over a range, the vibrating screen bodies  22  may be stacked in a manner as shown in FIG.  9 . The material to be sized  14  would then flow into the upper vibrating screen body  108 . The particles that were too large to flow through the upper vibrating screen  110  will then come out of discharge end  112 . However, the materials that flow through the upper vibrating screen  110  into the intermediate vibrating screen body  114  will then be vibrated along intermediate vibrating screen  116 . Hence, particles that would flow through upper vibrating screen  110 , but not intermediate vibrating screen  116 , would come out intermediate discharge  118 . Therefore, the particles coming out of intermediate discharge  118  are of a predetermined size range. For further refinement, a lower vibrating screen body  120  with a lower vibrating screen  122  is also included. From the lower discharge  124 , even finer size particles are discharged that would flow through upper vibrating screen  100 , intermediate vibrating screen  116 , but not lower vibrating screen  122 . 
     In the stacking of vibrating screen bodies as illustrated in FIG. 9, the coarser vibrating screens are at the top and the finer vibrating screens are at the bottom. From the lower vibrating screen body  120  is located a bottom chute  126 , with a bottom funnel  128 . Only the finest of particles would come out of bottom funnel  128 , which particles would flow through each of the upper vibrating screen  110 , intermediate vibrating screen  116 , and lower vibrating screen  122 . In this manner, a different range of sized particles can be determined in any given condition.