Patent Publication Number: US-7901271-B2

Title: Shimless dual arbor scrap chopper

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/621,860, filed Oct. 25, 2004, herein incorporated by reference. This application is a divisional of U.S. application Ser. No. 11/163,610, filed Oct. 25, 2005 now abandoned, the disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates to choppers that are used in scrap edge trimming of flat sheet metal or other scrap strip production processes that require effective collection and removal of large quantities of scrap strip material, more specifically the invention relates to a dual arbor chopper that does not require shims after the chopper knife blades are sharpened. 
     BACKGROUND OF THE INVENTION 
     During processing of sheet materials such as sheet metal, it is frequently necessary to subdivide rolls or pieces of sheet stock into narrower rolls or pieces. A slitter apparatus is typically employed for this purpose, with the apparatus including a plurality of cutting mechanisms which cut the sheet stock lengthwise to the desired narrower widths. An edge trimmer apparatus is typically employed on each side of the slitter to cut off the bad edges. 
     Attendant to slitting or edge trimming of sheet material in this fashion, it is common for opposite edge portions of the sheet stock to be cut, and recycled as scrap material. Because such pieces of scrap material have lengths corresponding to that of the original sheet stock, it is desirable to continuously cut the scrap edge portions as the slitter or trimmer apparatus is operated to slit the sheet stock. 
     Typical dual arbor scrap choppers utilize knives that are three-dimensional helical knives when mounted on the drum. Another type of knife blade used in dual arbor scrap choppers is a two-dimensional cutting knife blade that is made at least partially in the form of a radius and/or at least partially in the form of an ellipse. Such a knife blade and associated arbor is disclosed in co-owned U.S. Pat. No. 4,858,506, incorporated herein by reference. 
     Knife blades used in chopping scrap become dull with use and need to be sharpened. The knife blades are sharpened by removing material from at least one side of the knife blade adjacent the cutting edge. When the material is removed, a shim is required between the arbor and the knife blade to compensate for the loss of material and to ensure that the cutting edge remains in the proper location with respect to the arbor and to the opposite cutting edge of the knife blade mounted on the opposing arbor. The installation of the shims can be time consuming as the correct shim width must be determined and installed. These prior art systems will be discussed in greater detail below. 
     It would therefore be an advantage to provide a dual arbor chopper that utilized a knife in a manner that did not require shims throughout the life of the knife. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes at least one disadvantage of the prior art by providing a dual arbor chopper comprising: a support housing; a pair of oppositely disposed arbors rotatably positioned within the housing, each arbor having at least one blade attachment recess, the blade attachment recess including a first planar register surface oblique to a longitudinal axis of the arbor; at least one blade on each arbor positioned in a corresponding blade attachment recess, each blade including an active cutting edge; and a clamping block adapted to secure each blade in position within the corresponding blade attachment recess, wherein the clamping block is moveable toward and away from the first planar register surface to compensate for different blade widths; wherein the rotation of the arbors causes corresponding active cutting edges to progressively shear a material fed between the arbors. 
     At least one embodiment of the present invention provides a dual arbor chopper comprising: a support housing; a pair of oppositely disposed arbors rotatably positioned within the housing, each arbor having at least one blade attachment recess, the blade attachment recess formed having a first planar register surface oblique to a longitudinal axis of the arbor and a second register surface generally perpendicular to the first planar register surface; a drive means interconnecting and controlling relative rotational speed of the arbors; at least one blade on each arbor, each blade comprising a first face side generally parallel to a second face side, a first end opposite a second end, and a top surface opposite a bottom surface, wherein an active cutting edge is formed at the intersection of the top surface and the first face side; wherein each blade is positioned in a corresponding blade attachment recess such that the first face side registers against the first planar register surface of the arbor and the bottom surface of the blade registers against the second register surface of the arbor; and a clamping block registerable against the second face side of the blade; a fastener positioned through an aperture in the clamping block and the blade to attach the blade and the clamping block to the arbor; wherein the rotation of the arbors causes corresponding active cutting edges to progressively shear a material fed between the arbors. 
     Another embodiment of the present invention provides a method of sharpening a plurality of blades of a dual arbor chopper comprising the steps of: providing a dual arbor chopper comprising a support housing, a pair of oppositely disposed arbors rotatably positioned within the housing, each arbor having at least one blade attached to the arbor by a clamping block in a first position and at least one fastener, each blade comprising a first face side generally parallel to a second face side, and a top surface opposite a bottom surface, wherein an active cutting edge is formed at the intersection of the top surface and the first face side, wherein the first face side of the blade registers against the arbor and the clamping block registers against the second face side of the blade; removing the fastener and the clamping block from each arbor to release the blade when the active cutting edge of the blade is worn; sharpening each blade by grinding at least the first face side of the blade; attaching the blade to the arbor with a fastener and the clamping block such that the clamping block is positioned in a second position displaced from the first position by an amount equal to the material ground from the blade. 
     These and other advantages will be apparent upon a review of the drawings and detailed description of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in further detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a prior art dual arbor scrap chopper with associated drive unit; 
         FIG. 2  is front elevational view of the arbors of  FIG. 1  with two-dimensional knife blades positioned in the middle of a cut; 
         FIG. 3  is a cross-sectional view of the arbors of  FIG. 2  showing the dual arbor two-dimensional knife blade; 
         FIG. 4A  is perspective view of a standard technique used to sharpen a two-dimensional knife blade and  FIG. 4B  is a side elevational view of the knife blade showing the removed material due to sharpening; 
         FIG. 5  is a cross-sectional view of the prior art arbors of  FIG. 2  utilizing two-dimensional knife blades after sharpening and requiring a shim; 
         FIG. 6  is a cross-sectional view of a single prior art arbor of a dual arbor chopper utilizing a helical three-dimensional knife blade; 
         FIG. 7A  is side elevational view of a standard technique used to sharpen a three-dimensional knife blade and  FIG. 7B  is a perspective and standard elevational views of a typical the helical knife blade; 
         FIG. 8  is a cross-sectional view of the single prior art arbor of  FIG. 6  utilizing a helical three-dimensional knife blade after sharpening and requiring a shim; 
         FIG. 9  is a cross-sectional view of the dual arbors of the present invention utilizing a two-dimensional knife blade; 
         FIG. 10  is a cross-sectional view of the dual arbors of the present invention utilizing a two-dimensional knife blade after sharpening; 
         FIG. 11  is a perspective view of a face grinding sharpening of multiple two-dimensional knife blades; 
         FIG. 12  is a perspective view of associated face shims as used in the prior art; and 
         FIG. 13  is a perspective view of a two-dimensional knife blade used in an embodiment of the present invention as shown in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A prior art dual arbor scrap chopper  100  can be seen in  FIG. 1  of the drawings comprising a mounting enclosure  105  securing to a base  101  by a plurality of fasteners  102 . The mounting enclosure  105  has an opening at  103  in which is positioned a pair of rotating arbors  112  and  112 ′ with associated support bearings and inner-connected speed regulator gearing reduction mechanism connected to a motor  106  as will be well understood and known in the art. 
     A front elevational view of the arbors  112  and  112 ′ of the prior art chopper of  FIG. 1  is shown in  FIG. 2  and a cross-sectional view of arbors  112  and  112 ′ is shown in  FIG. 3 . Referring to  FIGS. 2 and 3 , arbors  112  and  112 ′ are shown with each arbor  112 ,  112 ′ utilizing a two-dimensional knife blade  114 ,  114 ′ attached to the arbor  112 ,  112 ′. The knife blade  114 ,  114 ′ is positioned in a blade seat  123 ,  123 ′ formed in each arbor  112 ,  112 ′. The blade seats  123 ,  123 ′ comprise a pair of oppositely disposed angularly aligned transverse recesses  104 ,  104 ′ which extend to an angular upstanding edge mount  140 ,  140 ′. The transverse recesses  104 ,  104 ′ are concave transversely perpendicular with the upstanding edge mount  140 ,  140 ′. A fastener  116 ,  116 ′ is positioned through each knife blade  114 ,  114 ′ to attach the knife blade  114 ,  114 ′ to the arbor  112 ,  112 ′. The knife blade  114  has a cutting face side  120  having a cutting edge  122  which cooperates with the cutting edge  122 ′ of the knife blade  114 ′ of the opposite arbor  112 ′. 
     After use, the cutting edges  122 ,  122 ′ become dull and need to be resharpened. The knife blades  114 ,  114 ′ are sharpened by removing a portion  148  (shown in phantom in  FIG. 4B ) of the face side  120  with a grinding wheel  150  as shown in  FIG. 4A and 4B  to create a sharpened knife blade  114 R having a new cutting edge  122 R. The face grind sharpening process of knife blades  114  is also shown in  FIG. 11 . It is noted that the cross-section of the knife blade  114  is generally rectangular such that the sharpening of knife blade  114  does not change the height of the cutting edge  122  when mounted in the arbor  112 . 
     Referring now to the dual arbor chopper  110 R shown in  FIG. 5 , the resharpened knife blades  114 R,  114 R′ are remounted on arbors  112 ,  112 ′ with a shim  124 ,  124 ′ used to replace the removed material such that the resharpened cutting edges  122 R,  122 R′ are re-positioned in the same location as when the knife blade  114 ,  114 ′ was in the new condition. A variety of shims  124  are also shown in  FIG. 12 . 
     Referring to  FIG. 6 , a cross-sectional view of a single arbor of a second prior art dual arbor chopper is shown with each arbor  212  utilizing a three-dimensional helical knife blade  214  attached to the arbor  212 . A fastener  216  is used to attach a mounting block  230  to the arbor  212  in a manner securing the knife blade  214  to the arbor  212 . The knife blade  214  has a cutting face side  220  having a cutting edge  222  which cooperates with the cutting edge of an opposing arbor (not shown). After use, the cutting edge  222  becomes dull and needs to be resharpened. The helical knife blade  214  is sharpened by mounting the knife blade  214  in a drum fixture  234  and removing a portion of a top side  226  of the helical knife blade  214  with a grinding wheel  250  as shown in  FIG. 7A  creating cutting edge  222 R. In  FIG. 7B , various views of a typical helical knife  214  are shown. It is noted that the top side  226  is a three dimensional surface that is not perpendicular to its side faces  228 . Referring now to  FIG. 8 , the sharpened knife blade  214 R is remounted on arbor  212  with a shim  240  used to replace the removed material such that the cutting edge  222 R is re-positioned in the same location as when the knife blade  214 R was in the new condition. In this case, the shim  240  radially elevates the knife blade. 
     The present invention will now be described in detail with reference to  FIG. 9  which shows a cross-sectional view of a dual arbor chopper  10  with each arbor  12 ,  12 ′ utilizing a two-dimensional knife blade  14 ,  14 ′ attached to the arbor  12 ,  12 ′. As best shown in  FIG. 13 , each blade  14 ,  14 ′ comprises a first face side  32 , generally parallel to a second face side  34 , a first end  36  opposite a second end  38 , and a top surface  42  opposite a bottom surface  44 , wherein an active cutting edge  22  is formed at the intersection of the top surface  42  and the first face side  32 , wherein the active cutting edge  22  is formed at least in part as a radius or an ellipse in the axial direction of the arbor  12 . Referring again to  FIG. 9 , each arbor  12 ,  12 ′ comprises at least one blade attachment recess  23 ,  23 ′ formed by a first planar register surface  40 ,  40 ′ and a second register surface  4 ,  4 ′ generally perpendicular to the first planar register surface  40 . Second register surface  4  may be concave transversely to correspond to the curved bottom surface  44  of the blade  14  as shown in the prior art arbor  112  of  FIG. 2 . Each blade  14 ,  14 ′ is positioned in a corresponding blade attachment recess  23 ,  23 ′ such that the first face side  32 ,  32 ′ registers against the first planar register surface  40 ,  40 ′ of the arbor  12 ,  12 ′ and the bottom surface  44 ,  44 ′ of the blade  14 ,  14 ′ registers against the second register surface  4 ,  4 ′ of the arbor  112 ,  112 ′. A fastener  16 ,  16 ′ is positioned through a clamping block  18 ,  18 ′ and an aperture  13 ,  13 ′ in the knife blade  14 ,  14 ′ to attach the knife blade  14 ,  14 ′ to the arbor  12 ,  12 ′. The clamping block  18 ,  18 ′ is utilized to provide a backing for the knife blade  14 ,  14 ′ against the cutting force during operation of the chopper  10 . 
     The orientation of the blade recess  23 ,  23 ′ of arbor  12 ,  12 ′ of the present invention is opposite that of a conventional two-dimensional knife bladed arbor  112  as shown in  FIG. 3 . In the present invention, the first face side  32 , or cutting face side of the knife blade  14  registers against the upstanding surface  40  of the arbor  12 . In the prior art arbor  112 , the cutting face side  120  was opposite the upstanding surface  140  of the arbor  112 . 
     After use, the cutting edge  22  of the blade  14  of the present invention becomes dull and needs to be resharpened. The knife blade  14  is sharpened by removing a portion of the face side as previously shown in  FIG. 4A and 4B  to create knife blade  14 R having cutting edge  22 R. Referring now to  FIG. 8 , the knife blade  14 R is remounted on arbor  12  such that the newly formed cutting face side  32 R registers against the surface  40  of the arbor  12 . Newly formed cutting edge  22 R remains in the same location as when the knife blade  14  was in the new condition. The fastener  16  is tightened to move the clamping block  40  laterally to compensate for the change in material thickness of the knife blade  14 . No shims are required with the arbor/knife blade of the present invention, saving the set-up time required when using shims. 
     The knife blades of the present invention may have four cutting edges as the knife blades disclosed in co-owned U.S. Pat. No. 4,858,506. The knife blades are not intended to be limited to four cutting edge configurations as the present invention will also work with similar two dimensional knife blades having one or more cutting edges. 
     For knife blades used in the present invention having multiple cutting edges, the term active cutting edge means the cutting edge that is actually positioned to make the cut and the remaining cutting edges are considered inactive cutting edges. It is also noted that dual arbor choppers of the present invention and in the prior art may utilize what is referred to as a master shim on the register surface of the arbor. The master shim is produced by the dual arbor chopper manufacturer to properly position cutting edge of the knives when the knife blades are attached to the arbor. The master shim is used due to the difficulty of final machining the register surface of the arbor to ensure proper positioning of a blade. Once the master shim is attached to the register surface during manufacturing, it does not need to be replaced or modified. The master shim is not shown in the present invention. For purposes of this invention, the master shim (not shown) is considered to be part of the register surface  40  of the arbor  12 . For purposes of this invention a shim is a thickness of material used to compensate for the loss of material of a knife blade in the sharpening process. The end result of the use of a shim is that the sharpened active cutting edge of the knife is repositioned where it was when it was in a new condition. 
     Although the present invention has been described above in detail, the same is by way of illustration and example only and is not to be taken as a limitation on the present invention. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.