Abstract:
A cutting tooth for a rotary cutter that has a mounting bore arranged such that when a fastener disposed in the mounting bore is used to attach the cutting tooth to a tooth holder, the cutting tooth is attached into the holder so as to pull both a rear trailing surface and a bottom radially inner surface into tight contact with abutting surfaces of the tooth holder.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates generally to a cutting tooth for a rotary cutter and more particularly to a cutting tooth mounting structure which holds the cutting tooth tighter against at least two abutting surfaces of a tooth holder. 
       BACKGROUND 
       [0002]      FIG. 1  of this patent document shows a representative figure for U.S. Pat. No. 5,950,945 to Schaller (which is incorporated herein by reference), wherein a replaceable tooth PA 1  has a leading face PA 2 , a trailing face PA 3 , a radially outer face PA 4  and a radially inner face PA 5 . The leading face PA 2  has cutting portion PA 6  on it. The trailing face PA 3  is disposed along a first plane PA 7  and a radially inner face PA 5  is disposed in a second plane PA 8 . The replaceable tooth PA 1  is held in place with a threaded fastener PA 10  disposed along a longitudinal axis PA 11  in a tooth holder PA 9 . The axis PA 11  is disposed at an angle of PAa with respect to the plane PA 8  coincident with the radially inner face PA 5 . 
         [0003]    Still referring to  FIG. 1 , the longitudinal axis PA 11  intersects the plane PA 8  at a point (PA 12 ) in front of the leading edge PA 2  of the tooth PA 1  as it rotates about a rotational axis (not shown). Due to that just described structural relationship, when the threaded fastener PA 10  of the Schaller device is tightened, the trailing face PA 3  of the Schaller cutting tooth PA 1 , as shown herein in  FIG. 1 , is pulled against the leading face PA 14  of the tooth holder PA 12 . However, also as a result of that tightening procedure, the bottom or radially inner face PA 5  of the Schaller tooth PA 1  has forces on it in use tending to cause it to be pulled away from the mating surface PA 15  of the tooth holder PA 12 . So, the tightness being increased on only one of the abutting surfaces PA 3 /PA 14 , instead of on both abutting surfaces, PA 3 /PA 14  and PA 5 /PA 15 , makes the tooth PA 1  less stable than it could otherwise be. This problem will be explained in more detail in the following paragraph and in relation to  FIGS. 1A and 1B . 
         [0004]      FIGS. 1A and 1B  show the forces on the Schaller prior art tooth PA 1  of  FIG. 1  wherein, as shown in  FIG. 1A , a vector PAV extending generally from the leading face PA 2  towards the trailing face PA 3  along the longitudinal center PA 11  can be broken into a component PAVC 1  perpendicular to and directed towards the trailing face PA 3  and a corresponding component PAVC 2  parallel to the trailing face PA 3  that is directed towards the radially inner face PA 5 ; and  FIG. 1B  shows a component PAVC 3  perpendicular to and directed away from (not towards as in the present invention) the radial inner face PA 5  and a corresponding component PAVC 4  parallel to the inner face PAVC 4  that is directed towards the trailing face PA 3 . 
         [0005]    Accordingly, there is a need for a cutting tooth and holder wherein a tightening of a cutting tooth fastener will pull both a rear or trailing face PA 3  and a bottom or radially inner face PA 5  of the tooth against abutting surfaces of a tooth holder, whereby both the rear and bottom surfaces of the cutting tooth are in a tight abutting relationship with the abutting surfaces of the tooth holder, as result of a positive force vector being induced against both of those surfaces. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The above identified need is at least partially met through provision of the apparatus described in the following detailed description, particularly when studied in conjunction with the drawings, wherein: 
           [0007]      FIG. 1  is a side view of a cutting tooth in a tooth holder of the type for attachment to a rotor such as that shown in U.S. Pat. No. 5,950,945 to Schaller; 
           [0008]      FIGS. 1A and 1B  show a force vector along a longitudinal center of a bore in the cutting tooth of  FIG. 1  broken into force vector components; 
           [0009]      FIG. 2  is a cross sectional view of a first embodiment of the cutting tooth of the present invention; 
           [0010]      FIG. 3  is a cross sectional view of the cutting tooth of  FIG. 2  shown in a tooth holder; 
           [0011]      FIGS. 4A and 4B  are cross sectional views of a second embodiment of the cutting tooth of the present invention, showing a breakdown of a force vectors due to bolt clamp force acting at the center line of the bore in the cutting tooth for comparison to the force vector analysis of the prior art, as shown in  FIGS. 1A and 1B  respectively; 
           [0012]      FIGS. 5A and 5B  are cross sectional views of a third embodiment of the cutting tooth of the present invention, showing a breakdown of a force vectors due to bolt clamp force acting at the center line of the bore in the cutting tooth for comparison to the force vector analysis of the prior art, as shown in  FIGS. 1A and 1B  respectively; and 
           [0013]      FIG. 6  is a top view of the cutting tooth of  FIG. 2 , showing two mounting bores in dashed lines. 
       
    
    
       [0014]    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 
       [0015]    Referring now to the drawings, wherein like reference numerals indicate identical or similar parts throughout the several views,  FIGS. 1 ,  1 A and  1 B show a typical prior art cutting tooth of the type mounted to a rotor and  FIGS. 2-6  show preferred embodiments of cutting teeth constructed in accordance with the present invention. 
         [0016]      FIG. 2  shows a cutting tooth body ( 1 ) adapted to be rotated about a rotary axis ( 13 ). The tooth body ( 1 ) has a leading face ( 2 ), a trailing face ( 3 ), a radially outer face ( 4 ) and a radially inner face ( 5 ). A radially outer part ( 6 ) of the leading face ( 2 ) has a cutting surface ( 6 ) on it. The trailing face ( 3 ) is disposed generally in a first plane ( 7 ) and the radially inner face ( 5 ) is disposed generally in a second plane ( 8 ). The cutting surface ( 6 ) may be in the form of a shear edge, a grinding surface, or any other edge or surface that facilitates a cutting, tearing, shredding, or other size-reducing action when contacting a body (not shown) that is to be nominally cut or reduced in size. 
         [0017]    A mounting bore ( 10 ) is disposed in the tooth body ( 1 ) and extends at least through the trailing face ( 3 ), the mounting bore ( 10 ) having a centrally-located longitudinal axis or centerline ( 11 ) of the mounting bore ( 10 ), the longitudinal axis ( 11 ) extending through the first plane ( 7 ). The mounting bore axis ( 11 ) is defined by an acute bore angle (a) relative to the radially inner face ( 5 ), the mounting bore axis ( 11 ) inclining away from the radially inner face ( 5 ) while approaching the leading face ( 2 ). This is graphically illustrated by the fact that the mounting bore axis ( 11 ) crosses the plane ( 8 ) behind the tooth ( 1 ) at point ( 12 ) as it rotates about a rotational axis ( 13 ), as contrasted from the prior art shown in  FIG. 1 , wherein the point PA 12  shown in  FIG. 1  is the point where the mounting bore axis PA 11  crosses the plane PA 8 , doing so in front of the leading face PA 2 . The acute angle (a) is ideally 7 degrees but can fall in the range of 2-15 degrees. The lower end of the given range 2-15 degrees ensures that a measurable downward force vector (VC 2 /VC 3 /VC 6 /VC 7 ) component would result upon mounting, while the upper end of the range 2-15 degrees takes into account the need for sufficient space/clearance to exist in order to facilitate the insertion of a given threaded fastener ( 25 ) into place. 
         [0018]    Looking to  FIG. 2  it is noted that the longitudinal axis ( 11 ) crosses the second plane ( 8 ) at an acute angle behind the trailing face ( 3 ) at a point ( 12 ) resulting in a positive force vector on both the trailing face ( 3 ) and the radially inner face ( 5 ) when the bolt ( 25 ) is tightened. This is in contrast to the prior art tooth (PA 1 ) of  FIG. 1  wherein the longitudinal axis (PA 11 ) crosses the second plane (PA 8 ) at an acute angle at point (PA 12 ) in front of the trailing face (PA 3 ) so that there is a positive force vector only on the trailing face (PA  3 ) but not on the radially inner face (PA 5 ) when the bolt/nut PA 10  is tightened. 
         [0019]    A rearmost part ( 15 ) of the radially inner face ( 5 ) lies in the second plane ( 8 ) is forward of the first plane ( 7 ) and a radially innermost part ( 16 ) of the trailing face ( 3 ) lies in the first plane ( 7 ) spaced radially outwardly from the second plane ( 8 ), thereby avoiding a sharp corner between the trailing face ( 3 ) and the radially inner face ( 5 ). In other words, the cutting tooth ( 1 ) forms a bevel face between points ( 15 ) and ( 16 ), the bevel face extending between the trailing face ( 3 ) and the radially inner face ( 5 ), the bevel face being at a respective bevel angle relative to each of the trailing face ( 3 ) and the radially inner face ( 5 ). The lack of a sharp corner at the junction of the trailing face ( 3 ) and the radially inner face ( 5 ) facilitates the adaptable/maneuverable positioning of the cutting tooth ( 1 ) during mounting thereof to the position of the tooth ( 1 ) in holder ( 21 ) as shown in  FIG. 3 . 
         [0020]    During rotation of the cutting tooth ( 1 ) about the rotary axis ( 13 ), the longitudinal axis ( 11 ) of the mounting bore is preferably disposed in a third plane which is perpendicular to the rotary axis ( 13 ), so that if there are two or more mounting bores  10 , they are essentially parallel with each other. But the axes ( 11 ) of the mounting bores ( 10 ) are not required to be parallel, as shown in  FIG. 6 . Only one mounting bore ( 10 ) is required, however. 
         [0021]    Referring to  FIG. 2 , the mounting bore ( 10 ) has a first bore opening ( 10   a ) defined in the leading face ( 2 ) and a second bore opening ( 10   b ) in the trailing face ( 3 ), as can be seen clearly in  FIG. 2 , though it is not a requirement for the bore ( 10 ) to extend that far. The first bore opening ( 10   a ) is spaced at a first opening distance from the radially inner face ( 5 ), and the second bore ( 10   b ) is spaced at a second opening distance from the radially inner face, the first opening distance being greater than the second opening distance.  FIG. 2  shows that the second bore ( 10   b ) is defined in the trailing face ( 3 ). In the preferred embodiments shown in  FIGS. 2 ,  3 ,  4 A and  4 B the second plane ( 8 ) intersects the first plane ( 7 ) at an acute angle (b) ( FIG. 2 ) as measured through the tooth body ( 1 ) from the trailing face ( 3 ) to the radially inner face ( 5 ). This geometry causes a preferred wedge like structure. But in the preferred embodiment of  FIGS. 5A and 5B  that angle (c) between the first plane ( 7 ) and the second plane ( 8 ) is not acute, but is oblique, so in some cases that angle may be 90 degrees or more. 
         [0022]    Referring now to  FIGS. 2 and 3 , in use, the cutting tooth ( 1 ) is attached to the outer periphery of a rotor ( 20 ) and is configured for rotating in the first direction around the rotary axis ( 13 ). A tooth mounting structure ( 21 ) is operatively attached to an outer portion of the rotor ( 20 ). The tooth mounting structure ( 21 ) has a first wall ( 22 ) disposed along the first plane ( 7 ) in abutment with the trailing face ( 3 ) of the cutting tooth and a second wall ( 23 ) disposed along the second plane ( 8 ) in abutment with the radially inner face ( 5 ) of the tooth. A bore ( 24 ) in the tooth mounting structure ( 21 ) has a longitudinal center coaxially disposed along the longitudinal axis ( 11 ) of the bore ( 10 ) in the tooth ( 1 ). A fastener such as threaded bolt ( 25 ) is disposed in both the mounting bore ( 10 ) in the cutting tooth and in the bore ( 24 ) in the tooth mounting structure ( 21 ) for holding the cutting tooth ( 1 ) in place. The bore ( 10 ) in the tooth ( 1 ) may be threaded to facilitate engagement with the threaded bolt ( 25 ) to hold the cutting tooth ( 1 ) in place. 
         [0023]    The fastener ( 25 ) is a threaded fastener such as a bolt ( 25 ), whereby rotation of the threaded fastener ( 25 ) in one direction pulls the trailing face ( 3 ) of the tooth in abutment with the first wall ( 22 ) of the tooth mounting structure, while at the same time pulling the radially inner face ( 5 ) of the cutting tooth against the second wall ( 23 ) of the tooth mounting structure. Further, rotation of the threaded fastener ( 25 ) in an opposite direction causes loosening of the tooth with respect to the tooth mounting structure. Of course the rotor could be any kind of a cutter or grinder. For example, it could be a drum on a brush chipper. 
         [0024]    Referring now to a second embodiment shown in  FIGS. 4A and 4B , a cutting tooth ( 101 ) is shown and is adapted to be rotated about a rotary axis ( 13 ) like that shown in  FIG. 3 . The cutting tooth body ( 101 ) has a leading face ( 102 ), a trailing, generally planar, face ( 103 ), a radially outer face ( 104 ), and a radially inner, generally planar, face ( 105 ). A radially outer part ( 106 ) of the leading face ( 102 ) has a cutting surface ( 106 ) on it. A mounting bore ( 110 ) disposed in the tooth body has a longitudinal center ( 11 ) oriented such that a vector (V) extending generally from the leading face towards the trailing face along the longitudinal center ( 11 ) can be broken into: 
         [0025]    a component (VC 1 ) ( FIG. 4A ) perpendicular to and directed towards the trailing face ( 103 ) and a corresponding component (VC 2 ) parallel to the trailing face ( 103 ) that is directed towards the radially inner face ( 105 ); and 
         [0026]    a component (VC 3 ) ( FIG. 4B ) perpendicular to and directed towards the inner face ( 105 ) and a corresponding component (VC 4 ) parallel to the radially inner face ( 105 ) that is directed towards the trailing face ( 103 ). Stated another way, a mounting bore ( 110 ) disposed in the tooth body ( 101 ) has a longitudinal bore centerline ( 11 ), the bore centerline ( 11 ) being positioned at an acute angle with respect to the radially inner face ( 105 ) and being oriented along a slope vector that can be broken into: 1) a rise component (VC 3 ) directed downward and perpendicular to the inner face ( 105 ); and 2) a run component (VC 4 ) parallel to the inner face ( 105 ) and generally directed towards the trailing face ( 103 ) as shown in  FIG. 4B . 
         [0027]    In the embodiment of  FIGS. 4A and 4B  the angle (c) between the trailing face ( 103 ) and the radially inner face ( 105 ) is acute forming a wedge shaped cutting tooth ( 101 ). 
         [0028]    The embodiment  201  of  FIGS. 5A and 5B  is essentially like the cutting tooth ( 101 ) of  FIGS. 4A and 4B  except that the angle (d) between the plane of the trailing face ( 203 ) and the radially inner face ( 205 ) is obtuse instead of acute. A mounting bore ( 210 ) disposed in the tooth body ( 201 ) has a longitudinal center ( 11 ) oriented such that a vector (V) extending generally from the leading face towards the trailing face along the longitudinal center ( 11 ) can be broken into: 
         [0029]    a component (VC 5 ) ( FIG. 5A ) perpendicular to and directed towards the trailing face ( 203 ) and a corresponding component (VC 6 ) parallel to the trailing face ( 203 ) that is directed towards the radially inner face ( 205 )); and 
         [0030]    a component (VC 7 ) ( FIG. 5B ) perpendicular to and directed towards the inner face ( 205 ) and a corresponding component (VC 8 ) parallel to the radially inner face ( 205 ) that is directed towards the trailing face ( 203 ). 
         [0031]    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.