Abstract:
A cutting tooth for use with a stump cutting apparatus wherein the cutting tooth has a removable and replaceable cutting bit. The cutting bit is removably and nonrotatably secured to a head of an elongated shank with the shank secured to a mounting block or pocket of a stump cutting tool. A support member having an indexing surface is also removably and nonrotatably secured to the head of the elongated shank. Accordingly, the support member enables indexing the cutting bit to expose and use a plurality of cutting edges located on the periphery of the cutting bit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a stump cutting apparatus and more specifically to a cutting tooth used with a stump cutting apparatus. 
         [0004]    2. Description of Related Art 
         [0005]    Stump cutters or stump cutting machines are generally known in the art and are used to cut or grind stumps. A typical stump cutter includes a plurality of cutting tools mounted to a rotatable cutting wheel or drum. Placing the wheel or drum against a stump and rotating it causes the cutting tools, and more particularly individual cutting teeth, to engage and cut away the stump. Tool holders, sometimes referred to as pockets, are used to secure the cutting teeth to the cutting wheel. 
         [0006]    Due to the harsh environment these cutting teeth are subjected to replacement of the cutting teeth is almost a continuous job. For example, contact with the ground surface rapidly dulls the cutting edge of each cutting tooth. Further, if a cutting tooth strikes something hard such as a stone or rock the cutting bit or an edge thereof may break or chip requiring replacement of the cutting tooth. In addition, depending upon the particular cutting tooth design or style a carbide cutting bit is used. In many instances only a portion of the carbide cutting bit actually performs the cutting operation of thus wasting the remaining portion or cutting edge of the carbide cutting bit. Finally, continuous loading of the cutting tooth can cause cutting tooth failure including twisting or bending of the shank portion. In some instances, the tooth itself may break thus necessitating replacement. As cutting tooth replacement is costly both in material replacement costs and man-hours to remove and install each individual new cutting tooth it is desirable to use as much of the cutting bit as possible and replace only the worn or used cutting bit as necessary while maximizing use of the entire cutting bit. 
         [0007]    One type of cutting tooth and tool holder/pocket assembly is disclosed in the U.S. Pat. No. 5,743,314 the disclosure of which is hereby incorporated by reference. As set forth therein, the &#39;314 patent discloses a stump cutting tool assembly including a cutting tooth having an insert made of a solid material such as tungsten carbide and a generally cylindrical shank that extends through an aperture in a mounting block or pocket. As known, changing each cutting tooth can be expensive. Thus, reducing the amount of the cutting tooth that must be replaced and increasing the life of the cutting bit increases the overall desirability of a cutting tooth. Accordingly, there is a need in the art for a cutting tooth having a replaceable cutting bit for use with a stump cutting tool. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, the present invention provides a cutting tooth for use with a stump cutting apparatus of the type using a rotatable cutting wheel or drum. The cutting tooth includes an elongated shank having a head and a fastening mechanism. A cutting bit having an aperture therein is removably and nonrotatably disposed on the head of the shank. In addition, a support member also having an aperture therein is removably and nonrotatably disposed on the head of the shank adjacent the cutting bit. The cutting bit and support member are located on the head of the elongated shank; the fastening mechanism secures the shank to a pocket or mounting block. 
         [0009]    In a further embodiment, a plurality of connected segments join together to form the cutting bit. The segments are connected such that the interface or boundary between each of the respective segments forms a barrier that reduces crack travel or migration between the respective segments. In an additional embodiment, the cutting bit is connected to the support member. 
         [0010]    Accordingly the present invention provides a cutting tooth having a removable and replaceable cutting bit whereby the shank and support portions of the cutting tooth may be reused. 
         [0011]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a partial perspective view of a stump cutting tool having a cutting tooth according to the present invention attached to a cutting wheel of a stump cutting apparatus. 
           [0013]      FIG. 2  is a partial side view of the stump cutting tool of  FIG.1 . 
           [0014]      FIG. 3  is an exploded perspective view of the cutting tooth of  FIG. 1  according to the present invention. 
           [0015]      FIG. 4  is an end view of a cutting tooth according to the present invention. 
           [0016]      FIG. 5  is a side view of a cutting tooth according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    Referring now to the drawings, specifically  FIGS. 1-2 , a plurality of stump cutting tools, seen generally at  10 , are shown attached in pairs to a cutting wheel  12  of a stump cutting apparatus (not shown.) The stump cutting apparatus supports the cutting wheel  12  in a known manner for rotation in the direction shown by the arrow  14 . It should be understood that a stump cutting apparatus of this type is conventional and known in the art. Also, while shown herein with a cutting wheel  12 , the present invention may be used with a tool assembly attached to a cutting drum. 
         [0018]    Initially, it should be understood that the cutting tool assembly  10  includes a pocket or mounting block  16  and a cutting tooth  18 . As illustrated in  FIG. 1  the pockets or mounting blocks  16  are typically secured to the cutting wheel  12  in pairs. In the disclosed embodiment one of the pockets  16  includes a through bore or aperture having an adjacent countersunk portion  22  with the opposite pocket having a threaded bore or aperture. A fastener  26  extends through the through bore or aperture, through an aperture in the cutting wheel  12  and threadably engages the threaded bore or aperture on the opposite or complementary pocket  16 . Tightening the fastener  26  draws the respective pockets  16  together and sandwiches the cutting wheel  12  there between to secure the pockets  16  to the cutting wheel  12 . Although only two fasteners  26  are used to secure the pockets  16  to the cutting wheel  12 , additional fasteners  26  may also be used. 
         [0019]    Each pocket or mounting block  16  includes a cutting tooth holder portion  28  having an aperture  30  extending longitudinally, radially or circumferentially therethrough. Accordingly, the pocket or mounting block  16  is secured to the cutting wheel  12  with the cutting tooth  18  disposed and secured in the aperture  30 . 
         [0020]    Turning now to  FIGS. 3-5  there is shown in greater detail a cutting tooth  18  according to the present invention. The cutting tooth  18  includes a shank  32  having a fastening or retention mechanism, shown herein as a threaded portion  34  located on one end of the shank  32 , and a triangular shaped head  36  located on the opposite end. As shown, the threaded portion  34  receives a retaining member such as a nut  80  that secures the cutting tooth  18  to the mounting block or pocket  16 . Since the fastening mechanism functions to secure the cutting tooth  18  to the pocket or mounting block  16 , other fastening mechanisms including those using other retaining members can also be used. For example a spring-loaded retaining pin or detent member located on said shank, a retaining ring that fits into a groove on the shank  32  or a spring-loaded ring located on the shank  32  and engaging the pocket or mounting block  16  are suitable for retaining or fastening the cutting tooth  18  to the pocket or mounting block  16 . In addition, a tapered shank  32  that fits into a correspondingly tapered aperture located in the pocket or mounting block  16  is also suitable for securing the cutting tooth  18  to the pocket or mounting block  16 . Accordingly, while the threaded portion  34  is one fastening mechanism for attaching or fastening the cutting tooth  18  to the mounting block  16 , other fastening mechanisms are also suitable and come within the scope of the present invention. 
         [0021]    A flange member or radially extending lip  38  extends around the periphery of the head  36  adjacent a leading end or face  40  thereof. The flange member  38  provides a shoulder surface  42  that functions as a stop. While shown herein as an integral part of the head  36 , the flange member  38  can be removably attached to the head  36 . 
         [0022]    A support member  44  having a triangular shaped aperture  46  extending longitudinally from a leading end  48  to a trailing end  50  of the support member fits over and on the head  36 . The triangular shaped head  36  and triangular shaped aperture  46  are complementary shaped to provide a secure, non-rotatable mating configuration. Accordingly, other complementary shapes or configurations could also be used provided they enable placing the support member  44  on the head  36  in a non-rotatable manner. The support member  44  further includes a backing plate  52  located at the leading end  44  and a plurality of flat surfaces  54  extending longitudinally about the outer or peripheral surface  56  of the support member  44  adjacent to the trailing end  50  thereof. The flat surfaces  54  provide a detent mechanism enabling indexing or selective rotation of the cutting tooth  18  about the longitudinal axis of the shank  32 . Accordingly, while the preferred embodiment illustrates three flat surfaces  54  that provide a detent mechanism, other configurations or shapes that provide a rotatable indexing feature enabling the cutting tooth  18  to be selectively positioned at a plurality of positions with respect to the pocket or mounting block  16  are contemplated and are within the scope of the present invention. 
         [0023]    The support member  44  supports a cutting bit  58  made of a material such as tungsten carbide on the head  36 . The cutting bit  58  includes a triangular shaped aperture  60  complementary to the triangular shape of the head  36 , such that the cutting bit  58  fits on the head  36 . As set forth above, the shape or configuration of the aperture  60  in the cutting bit  58  is such that it provides a secure, non-rotatable mating configuration with the head  36 . Like the aperture  46  in the support member  44 , the aperture  60  in the cutting bit  58  may also have a variety of other complementary shapes or configurations. For example, the apertures may have a circular, square, rectangular, lobe or other shape and may include a serrated or grooved surface. As set forth herein, the support member  44  and the cutting bit  58  are placed on the head  36 . Since it is contemplated that the cutting bit  58  can be attached or fastened to the support member  44  by some type of fastening mechanism including welding, brazing, bonding, adhesive or mechanical fastener it is not necessary that the aperture  60  in the cutting bit  58  have a shape complementary to the head  36 . When positioning the cutting bit  58  on the head  36  separate or unconnected from the support member  44 , for example when the cutting bit  58  and the support member  44  are placed on the head  36  in a side by side stacked relationship, it is desirable that the aperture  60  of the cutting bit  58  be complementary to the cross-sectional shape of the head  36 . In addition, it is not necessary that both of the apertures  46 ,  60  of the respective support member  44  and cutting bit  58  be complementary to one another. In some instances it may be desirable to use a different configuration for each aperture with the head  36  being shaped accordingly. For instance, the aperture  60  of the cutting bit  58  may be cylindrical while the aperture  46  of the support member  44  may have a triangular shaped cross section. 
         [0024]    As shown, the corners or vertices  46   a,    60   a  of the aperture  46  in the support member  44  and the aperture  60  in the cutting bit  58  are rounded or curved to reduce potential cracking or failure at these corners or vertices  46   a,    60   a.  In addition, is not necessary that the apertures  46 ,  60  of the respective support member  44  and cutting bit  58  have a shape complementary to the vertices or corners of the head  36 . For example, the vertices  46   a,    60   a  of the respective apertures  46 ,  60  may include a small cylindrical aperture at the apex of the each vertex as such a structure is known to help reduce cracking at the vertex or intersection of respective sides of the apertures  46 ,  60 . It should be understood that the respective apertures  46 ,  60  of the support member  44  and cutting bit  58  need only be complementary to the shape of the head  36  to a degree necessary to prevent relative rotation between the respective components. 
         [0025]    As illustrated in  FIGS. 2-4  a portion of the triangular shaped aperture  60  has a slightly larger size  60   b  that forms a ledge or seat  62  at the intersection of the respective triangular shaped apertures  60 ,  60   b.  Accordingly, as the cutting bit  58  is positioned on the head  36  of the shank  32 , the flange member  38  engages the ledge or seat  62  to retain the cutting bit  58  and the corresponding support member  44  on the head  36  of the shank  32 . 
         [0026]    The peripheral edge  64  of the front surface  66  of the cutting bit  58  defines a cutting edge  68 . In accordance with a further aspect of the present invention, the cutting bit  58  is formed from a plurality of segments  70   a,    70   b,    70   c.  As illustrated in  FIG. 3  the cutting bit  58  includes three segments  70   a,    70   b,    70   c  fastened or joined together at segment lines or boundaries  72 , see  FIG. 4 . Brazing or welding is one bonding agent used for fastening or joining the respective segments  70   a,    70   b,    70   c  together to form the cutting bit  58 . Other bonding agents or mechanical means to join the respective segments can also be used, for example, structural adhesives or cements and mechanical fasteners can be used. Forming the cutting bit  58  of a plurality of segments  70   a,    70   b,    70   c  provides a plurality of interfaces each of which form a barrier that impedes crack travel or migration through the cutting bit  58 . For example, during the stump cutting process shock loading of the cutting bit  58 , typically occurring when the bit  58  strikes a hard surface or object, can cause cracks in the cutting bit  58 . Often these cracks propagate through the cutting bit  58  causing premature failure of the cutting bit  58  necessitating replacement. Accordingly, the interface  72  located between the respective segments  70   a,    70   b,    70   c  reduces the possibility that a crack formed in one segment  70   a,    70   b,    70   c  will travel to the remaining segments  70   a,    70   b,    70   c  thus increasing the overall life of the cutting bit  58 . In addition, the material or method used to fasten or join the segments  70   a,    70   b,    70   c  can also on reduce crack propagation through the cutting bit  58 . 
         [0027]    In addition, a wear plate  74  may be attached or connected to the front or leading end or face  40  of the head  36 . When a wear plate  74  is used, the ledge or seat  62  of the cutting bit  58  normally extends inward to a depth such that the wear plate  74  is flush with the surface of the cutting bit  58 . The wear plate  74  may be a hard material such as tungsten carbide that functions to reduce wear on the head  36  of the shank  32 . When used, the wear plate  74  is attached, typically by brazing, to the leading end or face  40  of the head  36 . 
         [0028]    Accordingly, the cutting tooth  18  is assembled by placing the cutting bit  58  and support member  44  on the head  36  of the shank  32 . The cutting bit  58  and the support member  44  can be attached or placed on the head  36  of the shank  32  separately or as a single member. For example, in some instances it may be advantageous to braze or otherwise attach the cutting bit  58  to the support member  44  prior to placing the components on the head  36  of the shank  32 . In most instances, the cutting bit  58  is placed on the head  36  of the shank  32  separate from the support member  44 . This arrangement allows replacement of only the cutting bit  58  when all of the cutting edges  68   a,    68   b,    68   c  of the respective segments  70   a,    70   b,    70   c  become dull. Thus, the shank  32  and support member  44  are reusable. 
         [0029]    Once assembled, the cutting tooth  18  is connected to the pocket or mounting block  16  by placing the shank portion through the aperture  30  in the cutting tooth holder portion  28  of the pocket  16 . The length of the aperture  30  is such that the threaded portion  34  of the shank  32  extends past the cutting tooth holder portion  28  and receives a threaded fastener such as a nut  80 . The flats  54  engage a ledge or abutment  82  on the cutting tooth holder portion  28  of the pocket  16  to prevent rotation of the cutting bit  58 . Accordingly, the cutting tooth  18  may be indexed to provide a new cutting edge by loosening the nut or fastener  80  and sliding the shank  32  outward, away from the tool holder portion  28 , to disengage the flat  54  of the support member  44  from the ledge or abutment  82 . The cutting tooth  18  is then rotated to provide a fresh cutting edge  68 , slid back into place where a flat  54  engages the ledge or abutment  82  and the nut  80  is retightened to secure the cutting tooth  18  in place. 
         [0030]    As disclosed herein, the cutting bit  58  includes three segments  70   a,    70   b,    70   c  that provide three cutting edges  68   a,    68   b,    68   c.  It should be understood that the cutting bit  58  does not need to include three segments but may be formed as a single piece. In addition, it may also include two or more segments as needed. Once these cutting edges become dull broken or otherwise unusable, the cutting tooth  18  is removed from the tool holder  28  and the support member  44  slides off the head  36  of the shank enabling removal and replacement of the cutting bit  58 . Once a new cutting bit  58  is installed, the entire cutting tooth  18  is placed back on the pocket or mounting block  16 . It should be understood that the present invention provides a cutting tooth  18  that facilitates replacement of the cutting bit  58  without requiring replacement of the entire cutting tooth  18  thereby reducing the overall cost. Further, by using a segmented cutting bit  58  overall cutting bit  58  failure is reduced thereby increasing the life of the cutting bit  58  and correspondingly increasing its usefulness and thus value. 
         [0031]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.