Abstract:
A tub grinder has a rotor with hammers that pass between adjacent slug bars. The slug bars have a riser bar portion disposed on the top of the slug bars, the riser bar portions extending vertically higher on one end of each respective slug bar than on the other end of each respective slug bar so that the hammers extend farther beyond the top of the riser bar and slug bar when they pass by first end than when they pass by the second end of the riser bar.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/452,554 filed Apr. 20, 2012, and is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to tub grinders and more particularly to an improvement to the slug bars of tub grinders. 
     BACKGROUND 
     Grinders for grinding hay or other materials to be ground are shown in U.S. Pat. No. 3,912,175 to Anderson, U.S. Pat. No. 3,966,128 to Anderson et al., U.S. Pat. No. 4,033,515 to Barcell et al., U.S. Pat. No. 4,134,554 to Morlock, U.S. Pat. No. 4,210,289 to Arnoldy, U.S. Pat. No. 4,846,411 to Herron et al., U.S. Pat. No. 5,419,502 to Morey, U.S. Pat. No. 5,626,298 to Arnoldy, and U.S. Pat. No. 6,412,715 to Brand et al., all of which are incorporated herein by reference in their entirety. 
     Tub grinders are used to reduce the size of many things such as bales of hay, tree branches, material from demolished buildings, etc. The material is placed in the top of the “tub” portion, for example with a grappling hook or front end loader on a tractor, then the tub portion rotates around a floor as can be seen in the prior art shown in  FIG. 1  of the drawings. An opening in the floor as shown in prior art  FIGS. 1 and 2  is provided with rotating hammers passing between slug bars, the hammers hitting the material in the tub, reducing the size to smaller particles that are delivered to an unloading conveyor to put the ground up particles in a pile or on a trailer or the like for transporting the ground material to another place. Typically the material to be ground is moving in the direction of the tub as shown by the arrow in  FIG. 1 , while the hammers are rotating in the direction shown in  FIG. 1 . 
     One of the problems associated with tub grinders is that they do not operate at optimum efficiency for all types of material to be ground. 
     Accordingly a tub grinder that can be easily adapted to efficiently grind different types of material is needed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above needs are at least partially met through provision of the apparatus described in the following detailed description, particularly when studied in conjunction with the drawings, wherein: 
         FIG. 1  is a typical prior art tub grinder; 
         FIG. 2  is a cross sectional view taken along line  2 - 2  of the prior art device of  FIG. 1 ; 
         FIG. 3  is a side elevational view of a slug bar with one preferred configuration of a riser bar welded to the top thereof and immediately above that integral structure is shown the riser bar alone, before it is welded onto the slug bar; 
         FIG. 3A  is an enlarged, partial cross sectional view taken along line  3 A- 3 A of  FIG. 3 ; 
         FIG. 4A  is a cross sectional view similar to the prior art view of  FIG. 2 , but showing a preferred embodiment of the present invention set up for grinding material that is relatively easy to grind; 
         FIG. 4B  is a cross sectional view similar to the prior art view of  FIG. 2 , but showing a preferred embodiment of the present invention set up for grinding material that is more usual or medium to grind; 
         FIG. 4C  is a cross sectional view similar to the prior art view of  FIG. 2 , but showing a preferred embodiment of the present invention set up for grinding material that is difficult or hard to grind; 
         FIG. 5  is a perspective view of the embodiment of  FIGS. 3 and 4B  as would be seen if looking at a tub grinder from the view of  FIG. 1  if it had the improvement of the present invention thereon; 
         FIG. 6  is a side elevational view of a riser bar similar to the one shown in  FIG. 3 , but having a serrated and sharpened top surface on a part thereof; and 
         FIG. 6A  is a cross sectional view taken along line  6 A- 6 A of  FIG. 6 . 
     
    
    
     Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein. 
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein like reference numerals indicate identical or similar parts throughout the several views,  FIGS. 1 and 2  show a typical tub grinder  10  without the improvements of the present invention thereon and explained in the third paragraph above. The tub grinder  10  has a floor  11  that is fixed with respect to the frame of the tub grinder  10 . A rotating wall  12  is provided for moving the material within the walls of the tub wall  12  in the same general direction that the tub wall  12  is moving in order to move the material to a hammer mill  13  disposed in an opening in the floor of the tub grinder  10 . Rotation of the rotor  19  and hammers  14  in the direction shown in  FIG. 2  between slug bars  15  forces material above the floor  11  down into the area above screen  16  and the hammers also force the material through the screen  16  so that the ground up material can eventually be delivered to the unloading conveyor  17  for dumping the ground up material on the ground or into a trailer or wagon or the like. 
       FIG. 3  is a side elevational view of a slug bar  115  with one preferred configuration of a riser bar  121  welded by welds  122  to the top of prior art part  120  thereof as shown in  FIG. 3A , and immediately above that integral slug bar structure  115  in  FIG. 3  is shown the riser bar  121  alone, before it is welded onto the prior art slug bar  120 . 
       FIG. 4A  is a cross sectional view similar to the prior art view of  FIG. 2 , but showing a preferred embodiment of the present invention set up for grinding material that is relatively easy to grind, such as very dry or light porous material such as alfalfa hay or Styrofoam. The rotor  119  is rotated in the direction shown by the arrow in  FIG. 4A  and the swinging hammers  114  do not hit the material to be ground as the hammers  114  first rotate upwardly between the slug bars  120  and riser bar portions  121   a  until about point A on the riser bar portion  121   a . After that the hammers  114  gradually extend above the riser bar portions  121   a  more until they are only extending above the slug bars  120 . 
       FIG. 4B  is a cross sectional view similar to the view of  FIG. 4A , but showing a preferred embodiment of the present invention set up for grinding material that is average or medium to grind, such as wet or dense material like high moisture hay or fescue hay or medium porous material or the like. The rotor  119  is rotated in the direction shown by the arrow in  FIG. 4B  and the swinging hammers  114  do not hit the material to be ground as the hammers  114  first rotate upwardly between the slug bars  120  and riser bar portions  121  until about point B on the riser bar portion  121 . After that the hammers  114  gradually extend above the riser bar portions  121   a  more until they are only extending above the slug bars  120 . Since the riser bar portion  121  is longer an higher for more of the length of the riser bar  121  than for the riser bar portion  121   a  in  FIG. 4A , the hammers  114  only extend above the riser bar portions  121  starting at point B where the hammer is substantially vertically oriented, therefore since the hammers  114  extend above the riser bars for less time and do not extend above the riser bars as far during such relative time, a less aggressive approach is taken which requires less horsepower to rotate the rotor  119  and doesn&#39;t slow the revolutions per minute (rpm) as much as if the same medium to grind material was in the tub grinder arrangement shown in  FIG. 4A . Keeping the rpm of the rotor  119  (and therefore the rpm of an engine that rotates the rotor  119 ) above a certain predetermined level is important to the efficiency of a tub grinder and also reduces the wear and tear on such equipment such as the engine powering the tub grinder. The hammers  114  force the material through a screen  116  similar to  FIG. 2 . 
       FIG. 4C  is a cross sectional view similar to the view of  FIGS. 4A and 4B , but showing a preferred embodiment of the present invention set up for grinding material that is difficult or hard to grind, such as very dense material like wood, rubber, rubber tires or the like. The rotor  119  is rotated in the direction shown by the arrow in  FIG. 4C  and the swinging hammers  114  do not hit the material to be ground as the hammers  114  first rotate upwardly between the slug bars  120  and riser bar portions  121   c  until about point C on the riser bar portion  121   c . After that the hammers  114  gradually extend above the riser bar portions  121   c  more until they are only extending above the slug bars  120 . Since the riser bar portion  121   c  is longer an higher for more of the length of the riser bar  121   c  than for the riser bar portion  121   a  in  FIG. 4A  or riser bar portion  121  of  FIG. 4B , the hammers  114  only extend above the riser bar portions  121  starting at point C where the hammer  114  is substantially past vertically oriented, therefore since the hammers  114  extend above the riser bars  121   c  for less time than when riser bars  121  or  121   a  are used and do not extend above the riser bars  121   c  as far during such relative time, a less aggressive approach is being taken than when the riser bars  121  or  121   a  are used, which requires less horsepower to rotate the rotor  119  and doesn&#39;t slow the revolutions per minute (rpm) as much as if the same easy to grind or medium to grind material was in the tub grinder arrangement shown in  FIG. 4A  or  FIG. 4B  respectively. 
       FIG. 5  is a perspective view of the embodiment of  FIGS. 3 and 4B  as would be seen if looking at a tub grinder  10  from the view of  FIG. 1  if it had the improvement of the present invention thereon. Slug bars  120  have riser bar portions  121  welded to the top thereof and the hammers  114  are shown passing between the slug bars  120  and riser bar portions  121  to gradually begin grinding material as the hammers  114  move to the right in the direction of the arrow shown in  FIG. 5 . 
       FIG. 6  is a side elevational view of a riser bar  221  similar to the riser bar  121  shown in  FIG. 3 , but having a serrated and sharpened top surface  222  on a part thereof.  FIG. 6A  is a cross sectional view taken along line  6 A- 6 A of  FIG. 6  and shows how the serrated part  222  is also sharpened to an edge. Using this alternate embodiment will provide additional cutting action as the hammers  114  force the material against the sharpened serrated edge  222 . 
     Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept as expressed by the attached claims.