Abstract:
A clamping device for clamping an object to a structure, the device including a lever arm pivotally mounted relative to the structure, at least one member for urging one end portion of the arm in a direction to pivot the other end portion into engagement with the object, and an actuator supported by the housing and adapted to engage the one end portion of the arm to pivot the other end portion out of the engagement. The device is utilized to clamp a screen to a bed of a separator.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a vibrating screen separator and, more particularly, to such a separator utilizing a pretensioned screen on a vibrating bed for separating solids of different sizes or for separating solids from a liquid. 
     A typical screen separator consists of an elongated, box-like, rigid bed, and a screen attached to, and extending across, the bed. The bed is vibrated as the material to be separated is introduced to the screen which retains the relatively large size material and passes the liquid and/or relatively small sized material into the bed. The bed can be vibrated by pneumatic, hydraulic, or rotary vibrators, in a conventional manner. 
     In these type arrangements, it is difficult to positively clamp the screen to the bed during the separating process, yet permit the screen to be easily removed for cleaning or replacement. For example, rubber bladder systems have been used to clamp the screen, but suffer from excessive wear and are dependent on available air pressure for clamping force. Also, wedge devices, although having certain advantages, suffer from the fact that they use small parts that can be lost, damaged or become out of adjustment. Also, it takes an inordinately long time to replace both of these devices should they fail or wear out. 
     Therefore, what is needed is a device for clamping a separation screen to a vibrating bed, easily and quickly without the need for air pressure for the clamping force, yet is durable, does not come out of adjustment, and is reliable. Also needed is quick, external access and single component replacement in connection with the clamping devices which eliminate the need for complete screen unit disassembly. 
     SUMMARY OF THE INVENTION 
     The present invention, accordingly, is directed to a device for clamping an object, such as a separating screen, to a structure, such as a vibrating bed, according to which a lever arm is provided that is pivotally mounted relative to the structure. At least one member is provided for urging one end portion of the arm in a direction to pivot the other end portion into engagement with the object. An actuator is supported by the housing and adapted to engage the one end portion of the arm to pivot the other end portion out of the engagement. 
     There are several advantages to the system and method according to an embodiment of the present invention. For example, the clamping device clamps the screen to the bed easily and quickly without the need for air pressure for the clamping force, yet is durable, does not come out of adjustment, and is reliable. Also, quick, external access and single component replacement are provided for the clamping devices which eliminate the need for complete screen unit disassembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of a vibrating screen separator according to an embodiment of the present invention. 
     FIG. 2 is a view similar to that of FIG. 1 but depicting the separator in an assembled condition. 
     FIG. 3 is an enlarged isometric view of one of the clamping devices of FIGS. 1 and 2. 
     FIGS. 4 is an enlarged sectional view taken along the line  4 — 4  of FIG.  1 . 
     FIG. 5 is a view similar to that of FIG. 4 but depicting the clamping device of FIG. 4 in a different operating mode. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, the reference numeral  10  refers, in general, to an open housing, or bed, having a floor, or bottom wall  12 , and two side walls  14   a  and  14   b  that are respectively connected to the longitudinal edges of the bottom wall and extend perpendicularly thereto. A rear wall  16  is connected to the rear edge of the bottom wall  12  and to the rear ends of the side walls  14   a  and  14   b , and also extends perpendicularly to the bottom wall. 
     Four cross braces  18   a - 18   d  extend between the side walls  14   a  and  14   b  and slightly above the bottom wall  12 . The cross braces  18   a - 18   d  are connected to the side walls  14   a  and  14   b  in any known manner and function to add strength and rigidity to the bed  10 . 
     Two angle irons  20   a  and  20   b  are respectively connected to the inner surfaces of the side walls  14   a  and  14   b  in any known manner, and extend for the entire length thereof. Three spaced support bars  22   a - 22   c  extend between the side walls in the rear portion of the bed and are connected to the side walls in any known manner. The upper surfaces of the support bars  22   a - 22   c  extend flush with the upper surfaces of the angle irons  20   a  and  20   b , with the respective end portions of the support bars being notched to receive the angle irons. 
     Two angle irons  24   a  and  24   b  also are respectively connected to the inner surfaces of the side walls  14   a  and  14   b  and extend below, and parallel to, the angle irons  22   a  and  22   b , respectively. The angle irons  24   a  and  24   b  extend from the front ends of the bottom wall  12  to a location approximately midway between the respective ends thereof. Three spaced support bars  26   a - 26   c  extend between the side walls  14   a  and  14   b  in the front portion off the bed  10  and are connected to the side walls  14   a  and  14   b  in any known manner. The upper surfaces of the support bars  26   a - 26   c  extend flush with the upper surfaces of the angle irons  24   a  and  24   b , and the respective end portions of the support bars are notched to receive the angle irons. The support bars  26   a - 26   c  thus extend below, and parallel to, the support bars  22   a - 22   c.    
     As shown in FIGS. 1 and 2, a screen assembly  30  is provided in the rear portion of the bed  10  and rests on the upper surfaces of the upper angle irons  20   a  and  20   b  and the upper support bars  22   a - 22   c . The screen assembly  30  includes an outer rigid frame  32  (FIG.  1 ), a longitudinal support strut  34   a , and two spaced lateral cross-struts  34   b  and  34   c , all of which support a mesh-like material  36  which is connected to the frame and the struts in a conventional manner. The material  38  is selected so that it passes liquid and very small solid particles and retains larger particles of a certain size. The width of the screen assembly  30  is slightly less that the distance between the inner surfaces of the side walls  14   a  and  14   b  and, in the installed position shown in FIG. 2, the screen assembly extends for approximately one-half the length of the bed with its rear end abutting the inner surface of the rear wall  16 . 
     A screen assembly  38  is provided in the front portion of the bed  10  and rests on the upper surfaces of the lower angle irons  24   a  and  24   b  and the lower support bars  26   a - 26   c . The screen assembly  38  is identical to the screen assembly  30  and it extend for approximately one-half the length of the bed  10  with its front end extending substantially flush with the front end of the bed  10 . 
     It is understood that the bed  10  is vibrated by pneumatic, hydraulic, or rotary vibrators in a conventional manner as the material to be separated is introduced to the screen and that the screen functions to retain the relatively large size material and passes the liquid and/or relatively small sized material into the bed. 
     Two spaced clamping devices  40  are mounted to each side wall  14   a  and  14   b  for clamping the screen assembly  30  to the upper surfaces of the angle irons  20   a  and  20   b , and two spaced clamping devices  41  are also mounted to each side wall for clamping the screen assembly  38  to the upper surfaces of the angle irons  24   a  and  24   b.    
     One of the clamping devices  40  is shown in detail in FIGS. 3-5 and includes a substantially U-shaped elongated housing  42  having a mounting flange  42   a  extending from the upper end thereof for bolting to the outer surface of the side wall  14   b . Two posts  44   a  and  44   b  through openings in the respective side walls of the housing  42  with one end portion of each projecting out from its corresponding side wall. The corresponding ends of two compression springs  46   a  and  46   b  are attached to the projecting portions of the posts  44   a  and  44   b , respectively. 
     As better shown in FIGS. 4 and 5, a L-shaped support bracket  48  is disposed in the housing and includes a first, vertically extending leg  48   a  which extends across the lower rear portion of the housing, and a horizontally extending leg  48   b . Two openings (FIG. 3) are provided through the leg  48   a  for receiving bolts, or the like to mount the bracket  48  to the side wall  14   b.    
     A clamping lever arm  50  is pivotally mounted in the housing  42  about a fixed pin  52  mounted between two devises  54   a  and  54   b  (FIG. 3) extending from the leg  48   a  of the bracket  48 . The arm  50  extends through an opening in the leg  48   a  of the bracket  48 , and through an opening in the side wall  14   b.    
     A clamping pad  56  is mounted on the end portion  50   a  of the arm  50  extending inside the side wall  14   b . The other end portion  50   b  of the arm  50  extends in the housing  42  and two posts  58   a  and  58   b  (FIG. 3) extend from opposite sides, respectively, of the latter end portion and receive the other ends of the springs  46   a  and  46   b , respectively. The springs  46   a  and  46   b  thus pull the end portion  50   b  of the arm  50  upwardly as viewed in the drawings and, due to the pivotal mounting of the arm about the pin  52 , urge the end  50   a  of the arm, and therefore the pad  56 , downwardly and towards the angle iron  20   b . Since a side wall portion of the frame  32  of the screen assembly  30  rests on the angle iron  20   b  the pad  56  is thus urged into a clamping engagement with the latter frame portion. 
     An actuator, in the form of an air cylinder  60 , is mounted on the leg  48   b  of the bracket  48 , and has a movable plunger  62  that projects from the bottom of the cylinder and through an opening in the leg. The plunger  62  is adapted to extend in an axial direction in response to the flow of air from an external source (not shown) into the cylinder  60 , and is adapted to retract, under a spring force, or the like, when the air flow is terminated. Since the air cylinder  60  is conventional, it will not be described in any further detail. 
     In the retracted position of the plunger shown in FIG. 4, the springs  46   a  and  46   b  urge the pad  56  onto the corresponding upper surface of the frame  32  of the screen assembly  30  to clamp the frame between the pad and the angle iron  20   b . When it is desired to remove the screen assembly  30  for cleaning or replacement, the air cylinder  60  is actuated to extend the plunder  62  into engagement with the end portion  50   b  of the arm  50  with a force sufficient to overcome the force of the springs  46   a  and  46   b . Thus, the end portion  50   b  is pushed downwardly, and the pad  56  is pivoted away from the frame  32  to the position shown in FIG. 5 to release the clamping engagement with the frame. 
     It is understood that the other clamping device  40  that is mounted on the sidewall  14   b , the other two clamping devices  41  mounted on the side wall  14   b , and the corresponding clamping devices mounted on the side wall  14   a , all function in an identical manner. Thus, the screen assembly  30  can easily and quickly be clamped to and released from the angle irons  20   a  and  20   b  by the clamping devices  40 , and the screen assembly  38  can easily and quickly be clamped to and released from the angle irons  24   a  and  24   b  by the clamping devices  41 . 
     The present invention thus enjoys several advantages. For example, the clamping devices on both side walls of the bed securely clamp corresponding portions of the respective frames of the screen assemblies in the operative position of the screen assemblies, yet permit quick and easy disengagement of the clamping force. Also, each screen assembly is positively clamped in place by spring tension regardless of air pressure availability, while a pneumatic diaphragm cylinder is used to provide a quick and positive release. Further, the clamping devices are easily accessible and can be replaced on an individual basis as needed. Further, the system and method of the present invention features quick, external access and single component replacement instead of requiring complete screen unit disassembly. 
     It is understood that several variations may be made in the foregoing without departing from the scope of the invention. For example, the number of screens, angle irons, and clamping devices can be varied within the scope of the invention. Also, the clamping devices can be used in other applications, such as manufacturing processes, molding and welding fabrication. Further, the actuator can take other forms other than an air cylinder. 
     It is understood that other modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.