Patent Publication Number: US-11655821-B2

Title: Cutting blade assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/299,279 that was filed on Oct. 20, 2016, which claims priority to U.S. patent application Ser. No. 14/217,043 that was filed on Mar. 17, 2014, which claims priority to U.S. Provisional Patent Application No. 61/787,386 that was filed on Mar. 15, 2013 and U.S. Provisional Patent Application No. 61/887,080 that was filed on Oct. 4, 2013, all of which are hereby incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Cutting blade assemblies are used in a wide variety of applications to generally reduce the particle size of the medium being processed. Grinder pumps include a motor that rotates an impeller and an associated cutting blade assembly. Fluid and debris suspended within the fluid are drawn into the grinder pump where the cutting blade assembly attempts to reduce the particle size of the suspended debris before the impeller pumps the resulting slurry to a downstream location. 
     One issue common to most cutting blade assemblies, and especially those incorporated in a grinder pump or other fluid pumping applications, is the efficient processing and jam-free operation of the cutting blade assembly given the wide variety of debris encountered. For instance, with grinder pumps, debris including rags, mop heads, beverage containers, diapers, coins, and other objects can clog and jam the cutting blade assembly or place an increased load on the motor driving the cutting blade assembly. The various types of debris present many challenges because stringy debris (e.g., a mop head) can tend to wrap around the cutting blade assembly, resilient debris (e.g., plastic and rubber objects) can tend to wedge between moving parts of the cutting blade assembly, and hard debris (e.g., metallic objects) can wear or damage the cutting features of the cutting blade assembly. 
     To address these various problems associated with processing a variety of suspended debris, the drive motor torque can be increased, the cutting blade assembly strengthened, and the allowable particle size increased. However, none of these approaches presents an efficient, cohesive technique to address the persistent issues faced by cutting blade assemblies, and especially those cutting blade assemblies used in grinder pump applications. 
     SUMMARY OF THE INVENTION 
     In light of these problems, a need exists for a cutting blade assembly that provides a bidirectional and/or multifaceted cutting blade assembly to efficiently and effectively process various types of debris encountered by the cutting blade assembly. 
     Some embodiments of the invention provide a cutting blade assembly that is operably coupleable to a fluid pump and includes a cutting plate having an axial face and an opening defining a radial face that is skewed relative to the axial face. A cutting slot is formed in the cutting plate and intersects the axial face and the radial face. The cutting slot has an axial cutting edge at the intersection of the cutting slot and the axial face, and a radial cutting edge at the intersection of the cutting slot and the radial face. A cutting hub has an axial cutting arm that is positioned adjacent to the axial face and has a radial cutting arm that is positioned adjacent to the radial face. When the cutting plate and the cutting hub undergo relative rotation, the axial cutting arm of the cutting hub passes adjacent to the axial cutting edge and the radial cutting arm of the cutting hub passes adjacent to the radial cutting edge, so that the relative rotation of the cutting plate and the cutting hub defines a bidirectional cutting action. 
     Other embodiments of the invention provide a plurality of cutting slots that are formed in the cutting plate and intersect the axial face and the radial face, and each of the plurality of cutting slots is circumferentially spaced about and aligned generally perpendicular to the opening in the cutting plate. A cutting hub has a cutting arm that is positioned adjacent to the cutting plate. Each of the plurality of cutting slots has a base surface that is skewed axially inward from the axial face in the direction of the opening. When the cutting plate and the cutting hub undergo relative rotation, the cutting arm of the cutting hub passes adjacent to the cutting plate, so that the relative rotation of the cutting plate and the cutting hub defines a cutting action. 
     In some embodiments of the invention, a cutting hub has a central portion and a plurality of cutting arms that are circumferentially spaced about and extend radially outward from the central portion, each of the plurality of cutting arms is positioned adjacent to the cutting plate. The central portion of the cutting hub has at least one serration that is positioned between adjacent cutting arms of the plurality of cutting arms and that extends adjacent to the axial face of the cutting plate. When the cutting plate and the cutting hub undergo relative rotation, the plurality of cutting arms and the at least one serration of the cutting hub pass adjacent to the cutting plate, so that the relative rotation of the cutting plate and the cutting hub defines a cutting action between the plurality of cutting arms and the cutting plate, and between the at least one serration and the cutting plate. 
     In further embodiments of the invention, a cutting blade assembly is operably coupleable to a fluid pump. The cutting blade assembly comprises a cutting plate having an axial face and an opening defining a radial face that is skewed relative to the axial face. A first series of cutting slots is formed in the cutting plate and circumferentially spaced about the opening. Each of the first series of cutting slots intersects the axial face and the radial face, and defines a respective first axial cutting edge at the intersection of each of the first series of cutting slots and the axial face. Each of the first series of cutting slots establishes fluid communication with the opening in the cutting plate. A second series of cutting slots is formed in the cutting plate and circumferentially spaced between adjacent ones of the first series of cutting slots. Each of the second series of cutting slots intersects the axial face to define a respective second axial cutting edge at the intersection of each of the second series of cutting slots and the axial face. A cutting hub is positioned in the opening and has a cutting arm adjacent to the axial face. The cutting arm defines an arcuate front surface and a leading edge. When the cutting plate and the cutting hub undergo relative rotation, the leading edge of the cutting arm passes adjacent to the first axial cutting edges of the first series of cutting slots and the second axial cutting edges of the second series of cutting slots so that the relative rotation of the cutting plate and the cutting hub defines a scissor-type cutting action between the leading edge and both the first axial cutting edges and the second axial cutting edges. 
     Some embodiments provide a cutting blade assembly operably coupled to a fluid pump. The cutting blade assembly includes a cutting plate, a series of cutting slots formed in the cutting plate, and a cutting hub. The cutting plate has an axial face and an opening. Each of the series of cutting slots intersects the axial face and defines a respective axial cutting edge at the intersection of each of the series of cutting slots and the axial face. Also, each of the series of cutting slots includes a landing portion, the landing portion being a surface within the cutting slot that is parallel to the axial face. The cutting hub is positioned in the opening and has a cutting arm adjacent to the axial face. The cutting arm defines a leading edge. In some forms, each of the series of cutting slots includes a base surface having a landing portion, the landing portion being parallel to the axial face. 
     In other embodiments, a cutting blade assembly operably coupled to a fluid pump is provided. The cutting blade assembly includes a cutting plate having an axial face and an opening, a plurality of cutting slots formed in the cutting plate, and a cutting hub. Each of the plurality of cutting slots intersects the axial face to define a respective axial cutting edge at the intersection of each of the plurality of cutting slots and the axial face. Each of the plurality of cutting slots includes a through-hole extending through the cutting plate and a landing portion, the landing portion being parallel to the axial face. The cutting hub is positioned in the opening and has a cutting arm adjacent to the axial face. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an isometric view of a cutting blade assembly according to one embodiment of the invention for a grinder pump. 
         FIG.  2    is a partial section view along line A-A of  FIG.  1   . 
         FIG.  3    is an exploded isometric view of the cutting blade assembly and a portion of the grinder pump of  FIG.  1   . 
         FIG.  4    is a front plan view of the cutting blade assembly of  FIG.  1   . 
         FIG.  5    is a side plan view of the cutting blade assembly of  FIG.  1   . 
         FIG.  6    is a rear plan view of the cutting blade assembly of  FIG.  1   . 
         FIG.  7    is a partial detailed cross-sectional view along line B-B of  FIG.  4   . 
         FIG.  8    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  1   . 
         FIG.  9    is a cross section along line C-C of  FIG.  8   . 
         FIG.  10    is a front view of a cutting hub of the cutting blade assembly of  FIG.  1   . 
         FIG.  11    is a rear view of the cutting hub of  FIG.  10   . 
         FIG.  12    is a side plan view of the cutting hub of  FIG.  10   . 
         FIG.  13    is an isometric view of a cutting blade assembly according to a second embodiment of the invention for a grinder pump. 
         FIG.  14    is an isometric view of the cutting blade assembly of  FIG.  13   . 
         FIG.  15    is a front view of the cutting blade assembly of  FIG.  13   . 
         FIG.  16    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  13   . 
         FIG.  17    is another isometric view of the cutting plate of  FIG.  16   . 
         FIG.  18    is a front view of the cutting plate of  FIG.  16   . 
         FIG.  19    is a cross section along line D-D of  FIG.  18   . 
         FIG.  20    is an isometric view of a cutting hub of the cutting blade assembly of  FIG.  13   . 
         FIG.  21    is another isometric view of the cutting hub of  FIG.  20   . 
         FIG.  22    is an isometric view of a cutting blade assembly according to a third embodiment of the invention for a grinder pump. 
         FIG.  23    is an isometric view of the cutting blade assembly of  FIG.  22   . 
         FIG.  24    is a front view of the cutting blade assembly of  FIG.  22   . 
         FIG.  25    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  22   . 
         FIG.  26    is another isometric view of the cutting plate of  FIG.  25   . 
         FIG.  27    is a front view of the cutting plate of  FIG.  25   . 
         FIG.  28    is a cross section along line E-E of  FIG.  27   . 
         FIG.  29    is a partial cross section along line F-F of  FIG.  27   . 
         FIG.  30    is an isometric view of a cutting hub of the cutting blade assembly of  FIG.  22   . 
         FIG.  31    is another isometric view of the cutting hub of  FIG.  30   . 
         FIG.  32    is an isometric view of a cutting blade assembly according to a fourth embodiment of the invention for a grinder pump. 
         FIG.  33    is an isometric view of the cutting blade assembly of  FIG.  32   . 
         FIG.  34    is a front view of the cutting blade assembly of  FIG.  32   . 
         FIG.  35    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  32   . 
         FIG.  36    is another isometric view of the cutting plate of  FIG.  35   . 
         FIG.  37    is a front view of the cutting plate of  FIG.  35   . 
         FIG.  38    is a cross section along line G-G of  FIG.  27   . 
         FIG.  39    is a partial cross section along line H-H of  FIG.  27   . 
         FIG.  40    is an isometric view of a cutting hub of the cutting blade assembly of  FIG.  32   . 
         FIG.  41    is another isometric view of the cutting hub of  FIG.  40   . 
         FIG.  42    is an isometric view of a cutting blade assembly according to a fifth embodiment of the invention for a grinder pump. 
         FIG.  43    is an isometric view of the cutting blade assembly of  FIG.  42   . 
         FIG.  44    is a front view of the cutting blade assembly of  FIG.  42   . 
         FIG.  45    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  42   . 
         FIG.  46    is another isometric view of the cutting plate of  FIG.  45   . 
         FIG.  47    is an isometric view of a cutting hub of the cutting blade assembly of  FIG.  42   . 
         FIG.  48    is an isometric view of a cutting blade assembly according to a sixth embodiment of the invention for a grinder pump. 
         FIG.  49    is an isometric view of the cutting blade assembly of  FIG.  48   . 
         FIG.  50    is a front view of the cutting blade assembly of  FIG.  48   . 
         FIG.  51    is an isometric view of a cutting plate of the cutting blade assembly of  FIG.  48   . 
         FIG.  52    is another isometric view of the cutting plate of  FIG.  51   . 
         FIG.  53    is an isometric view of a cutting hub of the cutting blade assembly of  FIG.  48   . 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention. 
     One embodiment of a cutting blade assembly  10  is described in the context of a grinder pump  12 . However, the embodiments described herein can be incorporated into other suitable types of cutting devices, such as blenders, mixers, and food processors. 
       FIGS.  1 - 3    illustrate a grinder pump  12  including the cutting blade assembly  10  and a fluid pump  14 . The grinder pump  12  generally draws fluid and debris adjacent to an inlet  16  formed in a pump housing  18 . The fluid and debris are processed by the cutting blade assembly  10  and the resulting slurry is directed through an internal manifold  20  (as shown in  FIG.  2   ) toward an outlet  22  (as shown in  FIGS.  1  and  3   ). Specifically, the fluid pump  14  includes an electric motor  24  configured to rotate a central drive shaft  26  about a drive axis A. The drive shaft  26  is rotatably fixed to an impeller  28 , which is seated within the pump housing  18 . As the impeller  28  rotates, fluid and debris are drawn toward the inlet  16  and engaged by the cutting blade assembly  10 . 
     The cutting blade assembly  10  of one embodiment of the invention includes a disk-shaped cutting plate  30  that is seated into a mating cylindrical recess  32  formed in the pump housing  18 . The cutting plate  30  is rotatably fixed to the recess  32  by a series of bolts  34  that are engaged with mating threaded holes  35  formed in the recess  32 . The cutting blade assembly  10  further includes a cutting hub  36  that is rotatably coupled to the drive shaft  26  of the motor  24 , so that the cutting hub  36  rotates in unison with the impeller  28 . The cutting hub  36  is threaded onto the end of the drive shaft  26  and is further secured to the drive shaft  26  with a retaining ring  38 , which is seated in a recess  40  of the cutting hub  36  and retained by a screw  42  engaged with a threaded bore  44  (shown in  FIG.  2   ) in the end of the drive shaft  26 . To aid disassembly of the cutting plate  30  from the recess  32 , the cutting plate  30  includes several threaded bores  46  that are circumferentially spaced about the cutting plate  30 . Driving the bolts  34  into the threaded bores  46  will result in a tip of each bolt extending through the cutting plate  30  and engaging the recess  32 , urging the cutting plate  30  away from the recess  32 . 
       FIGS.  4 - 12    illustrate the structure of and interaction between the cutting plate  30  and the cutting hub  36  of the cutting blade assembly  10 . The cutting plate  30  and the cutting hub  36  are configured to establish both an axial cutting action (i.e., generally parallel to the drive axis A) and a radial cutting action (i.e., generally perpendicular to a direction that is parallel with the drive axis A). The axial cutting action and the radial cutting action are achieved via relative rotation between the cutting plate  30  and the cutting hub  36 . 
     As shown in  FIGS.  3  and  4   , the cutting plate  30  is generally disk-shaped and has a circular axial face  52  and an opening  54  through the cutting plate  30 . The opening  54  defines a cylindrical radial face  56  that is perpendicular (or alternatively skewed relative) to the axial face  52 . A plurality of cutting slots  58  are formed in the cutting plate  30  and extend through both the axial face  52  and the radial face  56 . Each cutting slot  58  defines an axial cutting edge  60  at the intersection of the cutting slot  58  and the axial face  52 , and defines a radial cutting edge  62  (as shown in  FIG.  7   ) at the intersection of the cutting slot  58  and the radial face  56 . The cutting slot  58  is a rectangular slot through the axial face  52  that defines the axial cutting edge  60 , an opposite back edge  64  (as shown in  FIG.  8   ), and a radially outer edge  66  connecting the axial cutting edge  60  and the back edge  64 . As shown in  FIGS.  8  and  9   , the cutting slot  58  includes a base surface  68  that is skewed axially inward from the axial face  52  in the direction of the opening  54  through the cutting plate  30 . The contoured base surface  68  is flush with the axial face  52  at the radially outer edge  66  of the cutting slot  58  and is angled toward a central plane of the cutting plate  30  near the radial cutting edge  62 . The increasing depth and flow area of the cutting slot  58  (relative to the axial face  52 ) helps direct axially cut slurry toward the radial cutting edge  62 , where the radial cutting action is performed to further reduce the particle size of the axially cut slurry. 
     The cutting plate  30  includes multiple cutting slots  58  that are identical in shape, that are perpendicular to the drive axis A and opening  54 , and that are circumferentially spaced about the drive axis A in a regular pattern. In other embodiments, the shape, number, and relative orientation of the cutting slots  58  may be altered to accommodate application-specific requirements. Furthermore, as shown in  FIG.  9   , the cutting plate  30  incorporates a mirrored set of cutting slots  70  that extend through another axial face  72  that is parallel and opposite to the axial face  52 , so that the cutting plate  30  may be flipped should the axial cutting edges  60  and/or the radial cutting edges  62  become dull, damaged, or otherwise degraded. 
     As shown in  FIG.  3   , the axial cutting action is generally accomplished as axial cutting arms  74  of the cutting hub  36  rotate adjacent to the axial cutting edges  60  in a scissor-type, shearing action. The scissor-type action establishes a zone of cutting engagement that progresses radially outward as the cutting hub  36  rotates relative to the cutting plate  30 . Specifically, the cutting hub  36  includes three circumferentially spaced axial cutting arms  74  that extend radially outward from a central, cylindrical hub portion  78 . Each of the axial cutting arms  74  of the cutting hub  36  has a leading edge  80  that is positioned adjacent to the axial face  52  of the cutting plate  30 . As the cutting hub  36  rotates, the leading edges  80  of each axial cutting arm  74  shear past the fixed axial cutting edges  60  of the cutting plate  30  (see  FIGS.  4 ,  5 , and  7   ). As shown in  FIG.  5   , the gap or spacing  37  between the leading edge  80  and the axial face  52  can be adjusted based on the particular application requirements, such as desired axial cut size and medium being processed. 
     As shown in  FIGS.  3 - 5   , each of the axial cutting arms  74  is substantially fin shaped and tapers from a wider and thicker base portion  82  adjacent the hub portion  78  to a narrower and thinner tip portion  84  at a distal end of the axial cutting arm  74 . As shown in  FIG.  4   , the axial cutting arm  74  has a generally arcuate front surface  86  and a generally planar rear surface  88 . The front surface  86  is rounded to aid in rejecting suspended debris that has not been sufficiently reduced in size by the axial cutting action. As shown in  FIG.  3   , the hub portion  78  is also dome-shaped to further aid in the rejection of undesirable debris being processed by the axial cutting action. As shown in  FIG.  11   , an undercut  90  is formed in the rear surface  88  to create a low pressure zone on the back edge  92  of the axial cutting arm  74  to help prevent debris being trapped or becoming stagnant as the axial cutting arm  74  rotates. The arcuate front surface  86  of the cutting arms  74  and the dome-shape of the hub portion  78  also minimize the magnitude of a torque spike of the motor  24  when debris comes into abrupt contact with the cutting hub  36 . 
     As shown in  FIGS.  10  and  11   , a series of serrations  94  are formed on the hub portion  78  between adjacent axial cutting arms  74 . The serrations  94  are incorporated to cut debris and prevent debris from becoming entangled with the cutting hub  36 . The serrations  94  extend from a midway point on the hub portion  78  and intersect the rear surface  88  of the cutting hub  36 , so that the perimeter cutting edges  98  are both adjacent to the axial face  52  and spaced further from the axial face  52  to engage larger debris with an additional cutting action. The shape, number, and placement of the serrations  94  may be adapted to meet a variety of particular application requirements. 
     Once the axial cutting action has occurred, the slurry continues downstream where it is subjected to the radial cutting action. Specifically, the radial cutting action occurs as radial cutting arms  100  of the cutting hub  36  sweep past the radial cutting edge  62  of the cutting plate  30  (as shown in  FIGS.  6  and  7   ). The cutting hub  36  includes several radial cutting arms  100  that are positioned adjacent to the radial face  56  as the cutting hub  36  rotates relative to the cutting plate  30 . The radial cutting arms  100  are circumferentially spaced about a cylindrical surface  102  that is orthogonal to the rear surface  88  of the hub portion  78 . Each radial cutting arm  100  has a leading edge  104  that is positioned adjacent to the radial face  56  of the cutting plate  30 . As shown in  FIGS.  6  and  7   , as the cutting hub  36  rotates, the leading edge  104  of each radial cutting arm  100  shears past the fixed radial cutting edges  62  of the cutting plate  30  effecting the radial scissor-type cutting action. As shown in  FIG.  7   , each of the radial cutting arms  100  extends from a base  106  adjacent to and extending from the rear surface  88  to a tip  108  that is circumferentially narrower than the base  106 . A channel  114  is defined in the base  106  of each radial cutting arm  100  adjacent to the rear surface  88 . A leading surface  110  of the radial cutting arm  100  is skewed relative to the rear surface  88 , and a trailing surface  112  (as shown in  FIG.  11   ) is orthogonal to the rear surface  88 . The skewed leading surface  110  reduces the required driving torque and also efficiently directs the resulting slurry, which has undergone both the axial and radial cutting action, toward the impeller  28 . The shape, placement, orientation, and number of radial cutting arms  100  may be altered to accommodate specific application requirements. 
     Once the radial cutting action is complete, the resulting slurry is urged by the rotating impeller  28  through the internal manifold  20  and ultimately to the outlet  22 . The illustrated construction of the cutting plate  30  and the cutting hub  36  (as shown in  FIG.  2   ) provides a generally constant inlet area that improves the efficiency of the overall cutting blade application. For instance, the cross sectional area of the opening  54  in the cutting plate  30  is generally constant over the axial length of the opening  54 . The relatively constant inlet area minimizes the velocity changes of the fluid/slurry as it travels through the cutting blade assembly  10  and associated pump components. In the cutting blade assembly  10 , the fluid speed is increased as it passes into and through the cutting slots  58 , reduces slightly downstream of the cutting slots  58 , and maintains approximately the same velocity before reaching the impeller  28 . The torque required to operate the cutting blade assembly  10  is further minimized by the swept back configuration of the axial cutting arms  74  and the radial cutting arms  100 . Furthermore, the scissor-type cutting employed in both the axial and radial cutting actions reduces the torque requirements as compared to a straight cutting action. The reduction in typical cut size also reduces the torque required (e.g., the example axial and radial cutting action results in a particle size not to exceed ⅛ inch by ⅛ inch). 
     In one embodiment, the cutting plate  30  and the cutting hub  36  may be investment cast from 440C stainless steel and subsequently hardened to 58-61 Rc. A variety of materials, including metals, plastics, and composites may be used to construct the cutting blade assembly given the specific application requirements. 
     A second embodiment of a cutting blade assembly  200  incorporating a multifaceted cutting configuration is described with reference to  FIGS.  13 - 21   . The cutting blade assembly  200  and associated grinder pump  202  are similar to the cutting blade assembly  10  and grinder pump  12  described above, but focuses on axial cutting. Therefore, the description of the cutting blade assembly  200  will generally discuss the main differences from the cutting blade assembly  10 . 
       FIGS.  15 - 21    illustrate the structure of and interaction between a cutting plate  204  and a cutting hub  206  of the cutting blade assembly  200 . The cutting plate  204  and the cutting hub  206  are configured to primarily establish an axial cutting action during relative rotation between the cutting plate  204  and the cutting hub  206 . 
     As shown in  FIGS.  14 - 18   , the cutting plate  204  is generally disk-shaped and has a circular axial face  208 . A plurality of cutting slots  210  are formed in the cutting plate  204 . Each cutting slot  210  includes an arcuate circumferential portion  212  and a radial portion  214  that converge at a circular opening  216  that extends through the cutting plate  204 .  FIG.  17    illustrates the backside of the cutting plate  204  defining a recess  232 . The openings  216  extend through the cutting plate  204  and terminate at the recess  232 , thereby allowing the slurry within the cutting slot  210  to exit into the recess  232 . The circumferential portion  212  defines a first axial cutting edge  218  and the radial portion  214  defines a second axial cutting edge  220  the intersection of the cutting slot  210  and the axial face  208 . The circumferential portion  212  of the cutting slot  210  includes a first base surface  222  that is skewed axially inward from the axial face  208 . Similarly, the radial portion  214  of the cutting slot  210  includes a second base surface  224  that is also skewed axially inward from the axial face  208 . The skewed first base surface  222  and second base surface  224  help direct the slurry toward and through the openings  216 , reducing the tendency of the slurry to clog. The radial portion  214  is also circumferentially angled or undercut (as shown in  FIGS.  15 ,  18 , and  19   ) to help maintain a sharp second axial cutting edge  220 , even as the radial portion  214  wears during use. A series of radially inward slots  226  are also formed in the axial face  208 . These inward slots  226  are circumferentially spaced and each defines a slot cutting edge  228  that is formed by a circumferentially skewed pocket  230 , similar to the radial portion  214  of the cutting slots  210 . In other embodiments, the shape, number, and relative orientation of the cutting slots  210  and inward slots  226  may be altered to accommodate application-specific requirements. 
     As shown in  FIGS.  14  and  15   , the axial cutting action is generally accomplished as axial cutting arms  234  of the cutting hub  206  rotate adjacent to the first axial cutting edge  218 , the second axial cutting edge  220 , and the slot cutting edge  228  in a scissor-type, shearing action. Specifically, the cutting hub  206  includes three circumferentially spaced axial cutting arms  234 . Each of the axial cutting arms  234  of the cutting hub  206  has a leading edge  236  that is positioned adjacent to the axial face  208  of the cutting plate  204 . As the cutting hub  206  rotates, the leading edges  236  of each axial cutting arm  234  shear past the first axial cutting edge  218 , the second axial cutting edge  220 , and the slot cutting edge  228  in a scissor-type fashion. 
     As shown in  FIGS.  14 ,  15 ,  20 , and  21    the cutting hub  206  includes a pocket or undercut  238  that is larger than the undercut  90  of the first example cutting hub  36 . In addition, a pair of deeper serrations  240  are formed in a dome-shaped hub portion  242 , in contrast to the three shallower serrations  94  of the first example cutting hub  36 . The shape, number, and placement of the undercut  238  and serrations  240  may be adapted to meet a variety of particular application requirements. 
     A third embodiment of a cutting blade assembly  300  having a multifaceted configuration is described with reference to  FIGS.  22 - 31   . The cutting blade assembly  300  and associated grinder pump  302  are similar to the cutting blade assembly  10  and grinder pump  12  described above, but emphasize axial cutting. Therefore, the description of the cutting blade assembly  300  will highlight the main differences from the preceding cutting blade assemblies  10 ,  200 . 
       FIGS.  23 - 31    illustrate the structure of and interaction between a cutting plate  304  and a cutting hub  306  of the cutting blade assembly  300 . The cutting plate  304  and the cutting hub  306  are configured to primarily establish an axial cutting action during relative rotation between the cutting plate  304  and the cutting hub  306 . 
     As shown in  FIGS.  23 - 27   , the cutting plate  304  is generally disk-shaped and has a circular axial face  308 . A series of four orthogonal and circumferentially spaced cutting slots  310  are formed in the cutting plate  304 . Each cutting slot  310  includes an arcuate end portion  312  and a radial portion  314 . The end portion  312  and the radial portion  314  define an axial cutting edge  318  at the intersection of the cutting slot  310  and the axial face  308 . With specific reference to  FIG.  29   , the cutting slot  310  includes a base surface  322  that is skewed axially inward from the axial face  308  toward a central opening  316  formed through the cutting plate  304 . As shown in  FIG.  29   , the base surface  322  includes a landing portion  323  near the central opening  316  that is generally parallel with the axial face  308 . The skewed arrangement of the base surface  322  helps direct slurry through the cutting slots  310  to the central opening  316 . The cutting slot  310  is generally circumferentially angled or undercut (as shown in  FIGS.  24 ,  27 , and  28   ) to help maintain a sharp axial cutting edge  318 , even as the axial face  308  wears during use. In addition, an inner portion  319  of the cutting slot  310  (shown in  FIG.  28   ) is generally perpendicular to the axial face  308 . A series of circumferential slots  326  of varying arc length are also formed in the axial face  308 . These slots  326  are circumferentially spaced in two general rings about the central opening  316  and each defines a slot cutting edge  328  and a skewed slot base surface  330  that is angled axial inward from the axial face  308 . In other embodiments, the shape, number, and relative orientation of the cutting slots  310  and circumferential slots  326  may be altered to accommodate application-specific requirements. 
     As shown in  FIGS.  24  and  25   , the axial cutting action is generally accomplished as axial cutting arms  334  of the cutting hub  306  rotate adjacent to the axial cutting edge  318  and the slot cutting edge  328  in a scissor-type, shearing action. Specifically, the cutting hub  306  includes three circumferentially spaced axial cutting arms  334 . Each of the axial cutting arms  334  of the cutting hub  306  has a leading edge  336  that is positioned adjacent to the axial face  308  of the cutting plate  304 . As the cutting hub  306  rotates, the leading edges  336  of each axial cutting arm  334  shear past the axial cutting edge  318  and the slot cutting edge  328  to reduce debris to the desired size. 
     A fourth embodiment of a cutting blade assembly  400  having a multifaceted configuration is described with reference to  FIGS.  32 - 41   . The cutting blade assembly  400  and associated grinder pump  402  are similar to the cutting blade assembly  10  and grinder pump  12  described above, but focus on axial cutting. Therefore, the description of the cutting blade assembly  400  will emphasize the main differences from the preceding cutting blade assemblies  10 ,  200 ,  300 . 
       FIGS.  33 - 41    illustrate the structure of and interaction between a cutting plate  404  and a cutting hub  406  of the cutting blade assembly  400 . The cutting plate  404  and the cutting hub  406  are configured to primarily establish an axial cutting action during relative rotation between the cutting plate  404  and the cutting hub  406 . 
     As shown in  FIGS.  33 - 37   , the cutting plate  404  is generally disk-shaped and has a circular axial face  408 . A series of four orthogonal and circumferentially spaced cutting slots  410  are formed in the cutting plate  404 . Each cutting slot  410  includes an arcuate end portion  412  and a radial portion  414 . The end portion  412  and the radial portion  414  define an axial cutting edge  418  at the intersection of the cutting slot  410  and the axial face  408 . With specific reference to  FIG.  39   , the cutting slot  410  includes a base surface  422  that is skewed axially inward from the axial face  408  toward a central opening  416  formed through the cutting plate  404 . As shown in  FIG.  39   , the base surface  422  includes a landing portion  423  near the central opening  416  that is generally parallel with the axial face  408 . The skewed arrangement of the base surface  422  helps direct slurry through the cutting slots  410  to the central opening  416 . The cutting slot  410  is generally circumferentially angled or undercut (as shown in  FIGS.  34 ,  37 , and  38   ) to help maintain a sharp axial cutting edge  418 , even as the axial face  408  wears during use. In addition, an inner portion  419  of the cutting slot  410  (shown in  FIG.  38   ) is generally perpendicular to the axial face  408 . A series of slots  426  of are also formed in the axial face  408 . The slots  426  are oriented generally radially outward from the central opening  316  and are skewed relative to a ray extending from a central point of the cutting plate  404 . In addition, each slot  426  defines a slot cutting edge  428 , a distal edge  429  that is angled relative to parallel sides of the slot  426 , and a skewed slot base surface  430  that is angled axial inward from the axial face  408 . The slot base surface  430  is skewed inward from the axial face  408  as it extends from an outer portion toward the central opening  416  of the cutting plate  404 . The configuration of the slots  426  helps prevent debris or slurry from becoming trapped or stagnant between the cutting hub  406  and the cutting plate  404 , and each slot  426  defines a pocket (i.e., the slot  426  does not extend through the cutting plate  404 ). In other embodiments, the shape, number, and relative orientation of the cutting slots  410  and slots  426  may be altered to accommodate application-specific requirements. 
     As shown in  FIGS.  34  and  35   , the axial cutting action is generally accomplished as axial cutting arms  434  of the cutting hub  406  rotate adjacent to the axial cutting edge  418  and the slot cutting edge  428  in a scissor-type, shearing action. The scissor-type action establishes a zone of cutting engagement that progresses radially outward during relative rotation. Specifically, the cutting hub  406  includes three circumferentially spaced axial cutting arms  434 . Each of the axial cutting arms  434  of the cutting hub  406  has a leading edge  436  that is positioned adjacent to the axial face  408  of the cutting plate  404 . As the cutting hub  406  rotates, the leading edges  436  of each axial cutting arm  434  shear past the axial cutting edge  418  and the slot cutting edge  428  in a radially outward progression. 
     A fifth embodiment of a cutting blade assembly  500  having a bidirectional, multifaceted configuration is described with reference to  FIGS.  42 - 47   . The cutting blade assembly  500  and associated grinder pump  502  are similar to the cutting blade assembly  10  and grinder pump  12  described above. Therefore, the description of the cutting blade assembly  500  will discuss the main differences from the preceding cutting blade assemblies  10 ,  200 ,  300 ,  400 . 
     The cutting blade assembly  500  includes a cutting plate  504  including an annular flange  505  that is coupleable to a pump housing  503 . A cylindrical portion  506  of the cutting plate  504  includes an annular surface  508  and an axial surface  510 . The cutting blade assembly  500  further includes a cutting hub  512  that includes three cutting arms  514  circumferentially spaced. Each cutting arm  514  includes an axial cutting portion  516  extending from a central hub  518  and a radial cutting portion  520  that extends generally orthogonally from the distal end of the axial cutting portion  516 . 
       FIGS.  44  and  45    illustrate the structure of and interaction between the cutting plate  504  and the cutting hub  512  of the cutting blade assembly  500  that establishes both an axial cutting action and a radial cutting action. The cutting plate  504  includes a plurality of cutting slots  522  having an axial portion  524  formed in the axial surface  510  and a radial portion  526  formed in the annular surface  508  of the cutting plate  504 . The axial portion  524  of each cutting slot  522  is oriented generally tangential to a central opening  528  formed in the cutting plate  504 . The axial portion  524  of each cutting slot  522  defines an axial cutting edge  525  at the intersection with the axial surface  510 . The recessed axial portion  524  intersects with the radial portion  526  proximate an outer perimeter of the cylindrical portion  506  of the cutting plate  504 . Fluid, debris, and slurry within the axial portion  524  is directed outward along the axial portion  524  toward the radial portion  526 . The radial portion  526  is oriented generally perpendicular to the annular flange  505  and includes skewed side walls  530 ,  532 . One side wall  530  of the radial portion  526  defines a radial cutting edge  534  at the intersection with the annular surface  508 . Openings  536  are formed in the radial portions  526  and extend through the cylindrical portion  506  of the cutting plate  504  and into a cavity  538  formed on the backside of the cutting plate  504 . Thus, slurry sized according to the openings  536  flows through the cutting slots  522 , through the openings  536 , and into the cavity  538 . 
     The cutting arms  514  of the cutting hub  512  define cutting edges that interact with the axial cutting edges  525  and radial cutting edges  534  of the cutting plate  504  to establish a scissor-type cutting action. Specifically, each cutting arm  514  defines an axial leading edge  540  along the axial cutting portion  516  and a radial leading edge  542  along the radial cutting portion  520 . The axial leading edge  540  shears past the axial cutting edge  525  while the radial leading edge  542  shears past the radial cutting edge  534  to perform respective axial and radial cutting functions. The radial leading edge  542  is skewed relative to the side walls  530 ,  532  to further aid the scissor-type cutting action. The axial cutting portion  516  of each cutting arm  514  includes an angled or undercut backside  544 . Similarly, the radial cutting portion  520  also includes an angled or undercut backside  546 . Both backsides  544 ,  546  are configured to prevent debris from becoming trapped or clogged between the cutting arms  514  and the cutting plate  504 . In addition, each cutting arm  514  defines a curved outer surface  548  to deflect debris and prevent clogging of the cutting blade assembly  500 . 
     In other embodiments, the shape, number, and relative orientation of the cutting slots  522  and cutting arms  514  may be altered to accommodate application-specific requirements. 
     A sixth embodiment of a cutting blade assembly  600  incorporating a bidirectional, multifaceted configuration is described with reference to  FIGS.  48 - 53   . The cutting blade assembly  600  and associated grinder pump  602  are similar to the cutting blade assembly  10  and grinder pump  12  described above. Therefore, the description of the cutting blade assembly  600  will emphasize the main differences from the preceding cutting blade assemblies  10 ,  200 ,  300 ,  400 ,  500 . 
     The cutting blade assembly  600  includes a cutting plate  604  including an annular flange  605  that is coupleable to a pump housing  603 . A frustoconical portion  606  of the cutting plate  604  includes a generally conical surface  608  and an axial surface  610 . The cutting blade assembly  600  further includes a cutting hub  612  that includes three cutting arms  614  circumferentially spaced. Each cutting arm  614  includes an axial cutting portion  616  extending from a central hub  618  and a radial cutting portion  620  that extends at an angle from the distal end of the axial cutting portion  616 . 
       FIGS.  49  and  50    illustrate the structure of and interaction between the cutting plate  604  and the cutting hub  612  of the cutting blade assembly  600  that establishes both an axial cutting action and a radial cutting action. The cutting plate  604  includes a continuous cutting slot  622  having repeating axial portions  624  formed through the axial surface  610  and radial portions  626  formed in the conical surface  608  of the cutting plate  604 . The axial portion  624  of each cutting slot  622  defines an axial cutting edge  625  at the intersection with the axial surface  610 . The radial portion  626  includes repeating slots  630  that are interconnected by slanted slots  632 . Each slot  630  and interconnecting slanted slot  632  defines a cutting edge  634  at the intersection with the conical surface  608 . Openings  636  are formed in the slots  630  and extend through the conical surface  608  of the cutting plate  604  and into a cavity  638  formed on the backside of the cutting plate  604 . Thus, slurry sized according to the openings  636  flows through the cutting slot  622 , through the openings  636 , and into the cavity  638 . 
     The cutting arms  614  of the cutting hub  612  define cutting edges that interact with the axial cutting edge  625  and cutting edge  634  of the cutting plate  604  to establish a scissor-type cutting action. Specifically, each cutting arm  614  defines an axial leading edge  640  along the axial cutting portion  616  and a radial leading edge  642  along the radial cutting portion  620 . The axial leading edge  640  shears past the axial cutting edge  625  while the radial leading edge  642  shears past the cutting edge  634  of the repeating cutting slot  622  to perform respective axial and radial cutting functions. The axial cutting portion  616  of each cutting arm  614  includes an angled or undercut backside  644 . Similarly, the radial cutting portion  620  also includes an angled or undercut backside  646 . Both backsides  644 ,  646  are configured to prevent debris from becoming trapped or clogged between the cutting arms  614  and the cutting plate  604 . In addition, each cutting arm  614  defines a curved outer surface  648  to deflect debris and prevent clogging of the cutting blade assembly  600  during operation. 
     In other embodiments, the shape, number, and relative orientation of the cutting slot  622  and cutting arms  614  may be altered to accommodate application-specific requirements. 
     It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications, and departures from the embodiments, examples, and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein. Various features and advantages of the invention are set forth in the following claims.