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[0001]    This application claims priority from U.S. Provisional Application No. 61/946,203, filed Feb. 28, 2014. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates to high production rock ripping tools, and more particularly to bucket type excavation and ripping tools for excavators and backhoes. 
       BACKGROUND 
       [0003]    Excavation tools of the types described herein are typically mounted to conventional excavators or backhoes having a dipper stick, with the tool mounted on the dipper stick. The tools are employed for excavation of difficult-to-excavate intermediate substrate, e.g. substrate between the category of loose soil or loose gravel and the category of solid rock. Attempts have been made to develop tools that are effective and efficient in excavating intermediate substrate. For example, an excavation tool for the removal of substrate is described in Horton U.S. Pat. No. 7,739,815, and a multi-tooth bucket approach where several teeth are mounted on the back side of a bucket is described in Arnold U.S. Pat. Nos. 4,279,085 and 4,457,085. The complete disclosures of all of these references are incorporated here by reference. Each of these approaches has been found to have drawbacks, and none is seen to be particularly efficient or effective for excavation of intermediate substrate with high production, wide width, high capacity buckets. 
       SUMMARY 
       [0004]    According to one aspect of the disclosure, a rock ripping tool mountable to an arm of an excavation machine for ripping engagement with a substrate comprises a tool body mounted for rotation from the arm, a pair of side plates and a curved back plate mounted to the tool body, a bottom plate having an angled front leading edge and mounted to span a space between the side edge plates, and a plurality of teeth comprising a first set of two or more teeth mounted to the angled front leading edge such that the tips of each tooth of the first set of two or more teeth lies on an arc having a first radius, a second set of one or more teeth mounted to at least one of the bottom plate and/or the back plate, such that the tips of each tooth of the second set of one or more teeth lies on an arc having a second radius greater than the first radius. 
         [0005]    Implementations of this aspect of the disclosure may include one or more of the following additional features. The first radius and the second radius intersect at a common axis of the ripping tool. The rock ripping tool comprises at least a third set of one or more teeth mounted to the bottom plate and/or the back plate, such that the tips of each tooth of the third set of one or more teeth lies on an arc having a third radius greater than the first radius and greater than the second radius. Each tooth of the plurality of teeth is angled such that an angle between a line bisecting the tooth and a line perpendicularly bisecting the respective arc where the tip of the tooth lies on the arc is at an optimum angle. Each tooth in the plurality of teeth is at the optimum angle. The optimum angle is in the range of about 35° to about 70°, e.g. the optimum angle is approximately 50°. The second set of teeth rips the substrate in a path between the paths of the teeth of the first set of two or more teeth. The side plates can have leading edges that define cutting profile edges. A lower portion of the back plate defines an outer surface lying on a radius having a center coaxial with at least one of the first radius and the second radius. Each tooth of the plurality of teeth is configured to engage the substrate sequentially and individually from each other tooth. 
         [0006]    According to another aspect of the disclosure, a rock ripping tool having a tool body and mountable to an arm of an excavation machine for ripping engagement with a substrate comprises a first set of teeth comprising at least two teeth mounted to the tool body such that the tips of each of the at least two teeth of the first set of teeth lies on an first arc having a first radius, and a second set of teeth comprising at least one tooth mounted to the tool body such that the tip of each tooth of the at least one tooth of the second set of teeth lies on an second arc having a second radius greater than the first radius, wherein each tooth of the plurality of teeth is configured to engage the substrate independently from each tooth in the first set of teeth and each tooth in the second set of teeth. 
         [0007]    Implementations of this aspect of the disclosure may comprise at least a third set of one or more teeth mounted to the bottom plate and/or the back plate, such that the tips of each tooth in the third set of one or more teeth lies on an arc having a third radius greater than the first radius and greater than the second radius. 
         [0008]    Advantages of the new rock ripping tool include that the tool can have a relatively wider bucket, e.g. to increase production without increasing the number of teeth on the front leading edge. Rather, by providing teeth at the back of the bucket, i.e. behind the leading edge, deeper cuts can be made with each pass, thus reducing or eliminating grooves in the substrate material, while keeping a relatively large side view engagement angle between the teeth, assuring one tooth at-a-time engagement. The back teeth are arranged to cut relatively deeper, i.e. as compared to the teeth at the leading edge, with increased radii, also resulting in increased production. Since the number of teeth is relatively increased, the wear on each tooth is proportionately reduced. The rock ripping tool of the disclosure is designed in particular for use in ripping medium hard rock. 
         [0009]    The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and in the description below. Other features, objects and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a somewhat schematic representation of a hydraulic excavator fitted with an example of the high production rock ripping tool of this disclosure. 
           [0011]      FIG. 2  is a left front perspective view of the high production rock ripping tool of  FIG. 1   
           [0012]      FIG. 3  is a bottom view of the high production rock ripping tool of  FIG. 1 . 
           [0013]      FIG. 4  is a left rear perspective view of the high production rock ripping tool of  FIG. 1 . 
           [0014]      FIG. 5  is a rear view of the high production rock ripping tool of  FIG. 1 . 
           [0015]      FIG. 6  is an enlarged side view of the ripping excavation tool of  FIG. 1 , e.g. a high production rock ripping tool of the disclosure, having multiple ripping teeth mounted to the tool in an arrangement with angular spacing between ripping teeth in a general direction of substrate ripping motion. 
           [0016]      FIG. 7  is a schematic representing a cross-sectional view of a pattern of substrate material ripped from a substrate during use of a high production rock ripping tool of the disclosure. 
       
    
    
       [0017]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0018]    Referring first to  FIG. 1 , a hydraulic excavator  10 , e.g. of the type suited for use with a high production rock ripping tool  12  of the disclosure, has a chassis  14 , tracks  16  and  17  for mobility, and a cab  18  for an operator. Extending from the chassis  14  is a boom  20  pivotally attached to the chassis  14  and a dipper stick  24  pivotally attached to the outboard end of the boom. A hydraulic actuator  26  articulates the dipper stick  24 . A high production rock ripping tool  12  can be mounted to the outboard end of the dipper stick  24  of the hydraulic excavator  10  by means of a quick-change coupler mechanism  28 , or it can be mounted directly to the dipper stick and linkage. A second hydraulic actuator  30  articulates the high production rock ripping tool  12  generally about an axis, H (see, also,  FIG. 6 ). A second axis, A, is an imaginary axis that is a combination of the rotational axis translation, which is preferably located near and generally above and forward of the dipper pivot rotation center, i.e., the axis, H, of hinge pin  32 , e.g. for ripping engagement, e.g., with the medium hard substrate, S. 
         [0019]    Referring also to  FIGS. 2 through 6 , the high production rock ripping tool  12  has a tool body including a tool body upper portion  34 , constructed for secure, releasable connection to the lower side of the quick-change mechanism  28  ( FIG. 1 ). The quick-connect coupler mechanism  28 , in turn, is connected to the dipper stick  24  and the hydraulic actuator  30  ( FIG. 1 ), or the tool can be connected directly to the dipper stick. Connected to the tool body upper portion  34  are two or more plates  36  that together generally form a tube. A set of rear and front side edge plates  38 ,  40  are mounted at respective upper ends to opposite ends of the tool body upper portion  34 . Each side edge plate  38 ,  40  extends generally perpendicular to the axis, A, of the high production rock ripping tool  12 . A curved back plate  42  is mounted to span a region between the side edge plates  38  and  40 . Also spanning side edge plates  38 ,  40 , at a bottom aspect of the tool  12 , opposite the tool body upper portion  34 , a rear bottom plate segment  44  and mid bottom plate segment  46 . Also partially spanning the bottom of the rock ripping tool  12  is a front bottom plate segment  48 . The front bottom plate segment  48  is forward of the mid bottom plate segment  46 , which is forward of the rear bottom plate segment  44 . The front bottom plate segment  48  is attached to a bottom front portion of the forward side edge plate  40 , approximately perpendicular to the second forward edge plate  40 . As best seen, e.g., in  FIGS. 2 and 4 , the rear bottom plate segment  44 , mid bottom plate segment  46 , and front bottom plate segment  48  do not necessarily lie on a plane and rather are angled relative to each other. In other implementations, the bottom plate  43  may be formed as a single, e.g. bent, plate having angled portions. 
         [0020]    Referring, e.g., to  FIG. 2 , the mid bottom plate segment  46  and front bottom plate segment  48  each has a plate leading edge  50 ,  52  that together form a discontinuous front leading edge  54  for cutting engagement with the substrate, S. The front leading edge plate  54  is angled laterally by angle, B, of  FIG. 3 , e.g. about 10° to about 35°. The angled front leading edge plate  54  may or may not have teeth mounted thereto; however, in the implementation shown in the present drawings, a first set of front teeth  60  is mounted to the front leading edge plate  54 . The side edge plates  38 ,  40 , and teeth  62  of the first set of teeth  60 , are laterally spaced apart along the axis A, and the teeth are positioned in a direction of substrate-engagement motion. 
         [0021]    The side edge plates  38 ,  40  can be beveled at their front aspect, e.g. to provide side cutting edges, and are shaped, thus providing a rearward side leading edge  39  and tooth  62 C and a forward side leading edge  41  and tooth  62 A that are spaced apart and approximately parallel to each other along the axis, A, e.g. as shown in  FIGS. 2 and 3 . Additional tooth  62 B is intermediately spaced along the front leading edge  54  at the front-most portion of mid bottom plate segment  46 . 
         [0022]    The plate leading edges  50 ,  52  of front leading edge  54  are also beveled to provide forward bottom cutting edges for cutting the packed substrate S. Additionally, the plate leading edges  50 ,  52  of front leading edge  54  can be scalloped, e.g. to help slice through the hard packed substrate, as shown, e.g., in  FIG. 2 . 
         [0023]    Referring further to  FIGS. 3-5 , in preferred implementations, the rock ripping tool  12  has three sets of removable teeth  60 ,  70 ,  80  mounted to the high production rock ripping tool  12 . The first tooth set  60  includes three teeth  62 A,  62 B,  62 C, which are mounted along on the front leading edge  54 . Each of the teeth  62 A,  62 B,  62 C of the first set of teeth  60  is mounted to a tooth adapter  90 , respectively, which is easily welded at the tip of the associated side edge plate  38  or the forward edge s of the rear, mid, and/or front bottom plate segments  44 ,  46 ,  48 , respectively, or the bottom plate  43 . Two teeth  72 A,  72 B, in a second tooth set  70 , are mounted on tooth adaptors  92 ,  94  positioned to the bottom and rear of the rock ripping tool  12 . The forward tooth  72 A of the second tooth set  70  is mounted to the rear bottom plate segment  44 , and the rearward tooth  72 B of the second tooth set  70  is mounted to the curved back plate  42 . A third tooth set  80  contains a single tooth  82 A, which is mounted upon a highly curved tooth adaptor  96  positioned at the rear of curved back plate  42 . 
         [0024]    Referring to  FIG. 6 , the three teeth  62 A,  62 B,  62 C of first tooth set  60  are all positioned to lie on arc  66  having a radius, R 1 , centered on axis, A, near and generally above and forward of the dipper pivot rotation center, i.e. axis, H, of hinge pin  32 . The two teeth  72 A,  72 B of the second tooth set are positioned to lie on arc  76  having the same center, A, as arc  66 , but with a relatively larger radius, R 2 . The tooth  82 A of the third tooth set  80  is positioned to lie on arc  86 , also of the same center, A, and having a radius, R 3 , larger than either of the radius, R 1 , and radius, R 2 . As seen from the side, the teeth are not positioned to lie in a common plane. Each tooth is spread at a similar engagement angle, e.g., about 15 to 18 degrees, to approximately equally spread the teeth for engagement with the substrate, S. 
         [0025]    Each set of teeth  60 ,  70 ,  80  is angled such that an angle Z 1 , Z 2 , Z 3  for each set of teeth, being the angle between the bisection of each tooth and the radii R 1 , R 2 , R 3  of the respective arcs  66 ,  76 ,  86 , is optimized to provide maximum penetration in the substrate. That is, all of the teeth are angled such that angles Z 1 , Z 2 , Z 3  are equalized to an optimum ripping angle, Z. The optimum angle, Z, depends on tooth manufacture, but typically lies in the range of about 35° to about 70°, or approximately 50°. 
         [0026]    Referring to  FIG. 5 , the three teeth  62 A,  62 B,  62 C, i.e. of the first tooth set  60 , are positioned to be laterally spaced from each other generally along the axis, A, of the high productions rock ripping tool  12 . In this implementation, the ripping teeth  62 A,  62 B,  62 C are equally spaced apart from each other, creating generally uniform intervening gaps  68 . 
         [0027]    The next two teeth  72 A,  72 B, i.e. of second tooth set  70 , are positioned to be laterally spaced apart from each other generally along the axis, A, creating intervening gap  78  between the two teeth. In this implementation, the teeth  72 A,  72 B are equally spaced apart and span the width of the tool  12 . The two teeth  72 A,  72 B are also laterally positioned between the front three teeth  62 A,  62 B,  62 C, i.e. in the intervening gaps  68  between the teeth of the first tooth set  60 . 
         [0028]    The rear tooth  82 A, i.e. of the third tooth set  80 , is positioned near the lateral center of the tool, i.e., within intervening gap  78  between teeth  72 A,  72 B. 
         [0029]    Referring in particular to  FIG. 3 , each tooth  62 A,  62 B,  62 C of the disclosure has a first ripper tooth portion  63 , terminating in a first ripper tooth tip  64 , and at least a second ripper tooth portion  65 , terminating in a second ripper tooth tip  66 . The twin or double tiger points or tips  64 ,  66  of first and second ripper tooth portions  63 ,  65 , respectively, are dimensionally spaced apart along the axis, A, by a dimension, W, e.g. about one-third of the length of the tooth. 
         [0030]    The edge plates  38 ,  40  with the bottom plate  43 , consisting of rear bottom plate segment  44 , mid-bottom plate segment  46 , and front bottom plate segment  48 , provide a bucket volume, V ( FIG. 2 ), of predetermined capacity for receiving material excavated from the substrate, S. The bucket volume, V. can be about 0.1 cubic yard for use with a mini (e.g., 6,000 pound weight) excavator to 6 or more cubic yards for use with a large (e.g., 300,000 pound) excavator. The rearward side edge plate  38  is shaped to support the bottom plate segments  44 ,  46  and tooth adapter  90  (to which a tooth  62 A is mounted, e.g. by pins (not show)), while also limiting side spillage, thus providing for maximum capacity of excavated substrate material. The width of the high production rock ripping tool  12  may be made larger than other rock ripping buckets, thereby permitting increased capacity. For example, the width of the tool can be 18 inches for use with a mini (e.g., 6,000 pound weight) excavator to 72 inches for use with a large (e.g., 300,000 pound) excavator. The bucket volume, V, of the high production rock ripping tool  12  fills and empties easily, thereby permitting the operator to scoop excavated materials efficiently. 
         [0031]    The high production rock ripping tool of  FIG. 1  thus improves the efficiency of excavating hard packed substrate, e.g. when compared to prior art tools, by focusing the breakout force one tooth at a time. As the operator is excavating hard packed substrate, the tool is rolled toward the operator such that the first tooth  62 A alone engages the material first. The concentration of machine breakout force on one tooth provides a concentration of the forces that are high enough to easily break up hard packed substrate, S, such as medium hard rock. 
         [0032]    During operation, the high production rock ripping tool  12  is pivoted all the way back at the end of the dipper stick  24 , and extended out as far forward of the chassis  14  as possible. The tool  12  is then lowered until the first tooth  62 A of the first tooth set  60  engages the substrate, S. The rock ripping tool  12  is then drawn downward, and in ripping motion, the second tooth, i.e. the tooth  62 B next adjacent to tooth  62 A, engages the substrate. Looking at the first tooth and the second tooth together, the first tooth engages with the hard packed substrate with full breakout force. When the second tooth engages the substrate, some of the load is shared with the first tooth. As the tool is rolled forward, the third tooth  62 C of first tooth set  60  then engages the substrate, S, and the load is shared between the several teeth that have engaged with the substrate. Throughout a good portion of the digging of the medium hard rock substrate, the tool  12  will have only one or two teeth engaged at any one instant due to the rolling operation of the bucket, thus always providing high forces for simplifying the excavation of the hard material. 
         [0033]    Referring to  FIG. 7 , there is shown a cross-sectional schematic representation of the pattern of profiles by which substrate, S, is ripped. Since, as described above, no two teeth are in alignment, when the high production rock ripping tool  12  is rolled, each tooth engages separately, so that each tooth portion fractures the groove cut by the preceding ripper tooth or teeth. The top three trapezoidal shapes  69 A,  69 B,  69 C represent the profile of material removed from the substrate, S, by the three teeth  62 A,  62 B,  62 C of the first tooth set  60 , located on the front leading edge  54 , after the tool  12  has been rotated and translated over the medium hard rock material. The flat bottom  100  of each trapezoid-shaped profile indicates the result following the cutting action of each tooth in the first tooth set  60 , and the angled sides  102  represent the broken out material. The flat bottoms  100  of the top profiles are at a depth,  67 , from the surface of the substrate. After the first three teeth  69 A,  69 B,  69 C have passed, the teeth have left the two raised grooves of material  104  located in the gaps  68 . 
         [0034]    The next two lower profiles  79 A,  79 B represent the next two teeth  72 A,  72 B of the second tooth set  70  passing through, ripping out the grooves with a deeper cut of relatively larger radius, removing the sections of material  79 A,  79 B to a depth  77 . The two teeth  72 A,  72 B also remove the raised grooves of material  104  in gaps  68  while leaving a new raised portion  106  between the sections of material  79 A,  79 B, in the gap  78 . The bottom shape or profile  89 A represents the final, deepest cut, performed by rear tooth  82 A of the third tooth set  80 , with the relatively largest radius R 3 , which removes material to the lowest depth,  87 , while also removing the raised groove of material  106 . Once all the teeth have engaged and cut through the substrate, S, a staggered form of a “V” shape or profile has been cut into the substrate material (e.g., rather than a flat bottom). 
         [0035]    The rear tooth can also be used as a pick when the tool is in the rolled forward position. 
         [0036]    A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, six teeth are described in one implementation of a high production rock ripping tool of this disclosure. In other implementations, more than or less than six teeth may be employed, positioned upon the surface of the tool. For example, four teeth may be positioned in the first tooth set  60  on the front leading edge  54 . In this implementation, the number of teeth in the second group  70  could still be two, and the third tooth set  90  could still include a single tooth in the center, for a total of seven teeth. 
         [0037]    Also, other arrangements of the teeth in the sets of teeth may be employed. For example, although in the implementation of the disclosure shown in the drawings the right outboard tooth  62 A is forward, left outboard tooth  62 C is rearward, and intermediate or central tooth  62 B is in the middle, other arrangements may be employed according to the disclosure. For example, the center tooth  62 B could be the first engaging tooth, with the right tooth  62 A engaging next, followed by the left tooth  62 C. 
         [0038]    Referring to  FIGS. 3-6 , in a preferred implementation, a lower portion  47  of the curved back plate  42  has an outer surface  49  with a radius R 4  having a center, A, that is co-axial with respective arcs  66 ,  76 ,  86  of the sets of tooth tips. This feature makes it easier to position and attach the tooth adaptors  92 ,  94  (or shanks) for teeth  72 A and  72 B on the curved back plate  42 , and also helps to keep the shanks as short as possible, which serves to reduce stresses on the curved back plate. This arrangement also reduces wear on the outer and bottom surfaces of the bucket  12  because as the bucket moves parallel to the ripped rock surface of the substrate forming the bottom of the trench, the bottom surface of the bucket is less exposed for scraping engagement along the bottom of the trench. In contrast, bottom surfaces of some buckets of conventional design have a “heel” configuration that wears quickly due to its exposure and due to its tendency for scraping engagement along the substrate surface forming the bottom of the trench. 
         [0039]    Also, in the implementation of the disclosure shown in the drawings, the high production rock ripping tool  12  is represented as being a bucket; however, other implementations are also possible. For example, rather than a closed bucket with side and bottom plates supporting attached teeth, a set of shanks could instead be attached to the tool body upper portion  34  in an arrangement to rip the substrate, S. For example, the teeth in a first set of staggered teeth  60  positioned relative to the axes of rotation and to the other teeth as described above may each be mounted to the end region of a shank. A second set of staggered teeth  70  that rip between, and deeper than, the first set  60  may also be mounted on shanks, and then a final tooth or set  80  positioned to rip between, and deeper than, the second set  70  would be mounted on still another shank. Each set of subsequent ripping teeth would rip on a relatively larger radius between the previous teeth, e.g. as described above. 
         [0040]    Accordingly, other embodiments are within the scope of the following claims.

Summary:
A rock ripping tool mountable to an excavation machine for engagement with a substrate has a rotatable tool body, a pair of side plates and a curved back plate mounted to the body, a bottom plate with an angled leading edge mounted to span a space between side plates, and a plurality of teeth, including a first set mounted to the front edge, the tip of each tooth lying on an arc having a first radius, a second set mounted to the bottom and/or back plate, the tip of each tooth lying an arc having a second radius greater than the first radius, and a third set of teeth mounted to the bottom plate and/or the back plate, with the tip of each tooth lying on an arc having a third radius greater than the first and second radii. Each tooth is configured to engage the substrate sequentially and individually.