Abstract:
A hydraulically activated shear is provided. The shear includes: a first jaw; a second jaw configured to slide past the first jaw in a shearing motion; and a first cutting plate attached to at least one side of the first and second jaws, the first cutting plate defining a shear edge and a shear surface, the shear surface having a positive camber with respect to a plane perpendicular to the jaws, wherein at least one of the first and second jaws is actuated by a hydraulic cylinder.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates generally to shears and, more particularly, to shears having cutting plates having a positive camber. 
       BACKGROUND 
       [0002]    Shears are often used to cut things. Shears, whether they be scissors for cutting paper or large hydraulic shears for cutting metal or other materials, operate on similar principles. Two relatively flat surfaces move past each other and are close enough to slide against each other. The material to be cut is located between the two surfaces and fails in shear causing the material to be cut. 
         [0003]    While the system works well for cutting a variety of objects, problems can develop. For example, simple paper cutting shears may not always cut if the paper is allowed to move substantially parallel to the shears and the two shearing surfaces move past the paper. The problem of material sliding down the shearing surface rather than being cut is not limited to paper cutting shears but happens in shears of all types. This can cause problems not only with small paper cutting shears but large hydraulic shears. 
         [0004]    For example, when using large hydraulic shears to cut objects such as metal, if the shears are worn, not properly adjusted, ill designed, or for variety of other reasons, the shears may not cut. Rather, in such instances, the metal may smear down the sides of the shear surfaces. This can cause a situation where the metal that was to be cut jams the jaws of the shear. It can even cold weld itself to the shearing surfaces on the shear jaws. This may result in a substantial delay while the operators of the hydraulic shears may need heavy tools to remove the fouling from the shear jaws. 
         [0005]    Heavy-duty shears such as hydraulically activated shears often use shear plates that are set within shear plate pockets. The shear plates are often removable from the shear jaws so that the shear plates (which are a high wear part) may be rotated, removed for maintenance or replaced when they become worn. Shims can provide a desired positioning of the shear plate within the shear plate pocket. Traditionally, shear plates are set to be at a neutral position or, in other words at 0 angle with respect to the opposing jaw. This may be referred to as a neutral camber. If the shear plates having negative angle, sometimes referred to as a negative camber, they may actually pull the workpiece to be sheared toward the jaws or create other problems. 
         [0006]    One example sheer is described in U.S. Pat. No. 6,926,217. This patent describes a shear jaw were a cross blade located at an end or tip of the jaw is located at an acute angle between 1 and 30 degrees. While this cross blade may assist in snipping material at the end or tip of the jaw, it does not address the problems associated with the cutting surfaces located at the sides of the jaw. The sides of the jaw is where a majority of the cutting or shearing often occurs. As result, the embodiment illustrated in this patent does not specifically address the problems described herein. 
         [0007]    In addition to these problems, substantial force may be required to cause some materials to be sheared. As result, shears are be very robustly built and operated by robust hydraulic systems. Furthermore, shears often are called upon to provide many cutting operations. As result, the shear surfaces or edges that help define the shear surfaces may become rounded or otherwise dull. 
         [0008]    Accordingly it would be desirable to provide a set of shears that can provide any, some, or all of the following characteristics: more reliably cut material rather than smearing it along the shear surfaces, reduce the amount of force required to cut material, and provide many cutting operations before needing any adjustments. 
       SUMMARY 
       [0009]    In one aspect, the disclosure describes a hydraulically activated shear. The shear includes: a first jaw; a second jaw configured to slide past the first jaw in a shearing motion; and a first cutting plate attached to a side of at least one of the first and second jaws, the first cutting plate defining a shear edge and a shear surface, the shear surface having a positive camber with respect to a plane perpendicular to the jaws, wherein at least one of the first and second jaws is actuated by a hydraulic cylinder. 
         [0010]    In another aspect, the disclosure describes a hydraulically activated shear. The shear includes: a first means for shearing; a second means for shearing configured to slide past the first means for shearing in a shearing motion; and a means for providing a cutting edge attached to a side of at least one of the first and second means for shearing, the first means for shearing defining a shear edge and a shear surface the shear surface having a positive camber with respect to a plane perpendicular to the jaws, wherein at least one of the first and second jaws is actuated by a hydraulic cylinder. 
         [0011]    In yet another aspect, the disclosure describes a shear. The shear includes a first jaw having a first side shear surface; a second jaw having a second shear surface wherein the first and second jaws are configured to slide past each other and the first and second shear surfaces are nearly but not parallel, the first shear surface has a positive camber and is cambered toward the second shear surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a machine equipped with a hydraulic shear in accordance with the disclosure. 
           [0013]      FIG. 2  is a perspective view of a shear in accordance with the disclosure. 
           [0014]      FIG. 3  is an exploded view of certain components of a shear in accordance with the disclosure. 
           [0015]      FIG. 4  is a perspective view of a shear in accordance with the disclosure. 
           [0016]      FIG. 5  is a perspective view of a cutting plate and shim located in a cutting plate pocket of a shear jaw in accordance with the disclosure. 
           [0017]      FIG. 6  is a partial cross-sectional view of a cutting plate mounted within a tapered cutting plate pocket in accordance with the disclosure. 
           [0018]      FIG. 7  is a partial cross-sectional view of a cutting plate mounted within a tapered cutting pocket in accordance with the disclosure. 
           [0019]      FIG. 8  is a partial cross-sectional view of a tapered cutting plate mounted in a cutting plate pocket in accordance with the disclosure. 
           [0020]      FIG. 9  is a partial cross-sectional view of a tapered cutting plate mounted in a cutting plate pocket in accordance with the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    With reference to the drawings, like reference numbers refer to like elements, FIG. illustrates a machine  10  having an arm  12 . The arm  12  includes a boom  14  pivotally attached to a stick  16 . The stick  16  includes a Shear  18 . The boom  14  is raised and lowered by hydraulic pistons and cylinders  20 . In the machine  10  illustrated in  FIG. 1 , the arm  12  is also rotated along with the cab  19  upon a tracked chassis  21 . The machine  10  illustrated in  FIG. 1  is one example of a machine  10  that can use a shear  18  in accordance with the disclosure. However, in other embodiments, other types of machines may also be used. In addition, in some embodiments, the shear  18  may not even be hydraulically actuated. However, in the example illustrated, and in the figures and discussed herein, the shear  18  is hydraulically actuated. 
         [0022]    As shown in  FIG. 1 , the stick  16  is pivoted by a hydraulic piston and cylinder  22 . The stick  16  is connected to the boom  14  via a pivotal connection  24 . The shear  18  includes a set of jaws  23 . The jaws  23  include a fixed jaw  26  and a movable jaw  28 . The movable jaw  28  is actuated by a hydraulic piston and cylinder  30  which connects to the movable jaw  28  at the pivotal connection  32 . The jaws  23  pivot with respect to each other about the pivotal connection  34 . In the example shown and described herein, one jaw  26  is a fixed jaw in another jaw  28  is a movable jaw. However, in other embodiments in accordance with the disclosure, both jaws  23  may be movable. Further, the jaws  23  are not limited to pivotal connections only. In some embodiments the jaws  23  may move laterally with the respect to each other or in some other manner. 
         [0023]      FIG. 2  illustrates a perspective view of a shear  18  in accordance with an embodiment. The shear  18  includes jaws  23 . The jaws  23  include a fixed jaw  26  and a movable jaw  28 . The fixed jaw  26  and the movable jaw  28  each have a hole  36  through which a pivot shaft  34  (shown in  FIG. 1 ) is placed. The jaws  23  pivot with respect to each other about the pivot shaft  34 . While jaw  26  is referred to as a fixed jaw and jaw  28  is referred to as movable, one of ordinary skill the art will understand that the two jaws  26  and  28  do pivot with respect to each other. In other embodiments both jaws  26  and  28  may be movable. Movable jaw  28  also has a hole  38  to provide a pivotal connection  32  (as shown in  FIG. 1 ) to the hydraulic piston and cylinder  30 . It is a hydraulic piston and cylinder  30  which actuates or moves the movable jaw  28 . In embodiments, the jaws  23  may be actuated by other means. 
         [0024]    Both the fixed jaw  26  and the movable jaw  28  have cutting plates  40 . The cutting plates are collectively referred to by reference numeral  40 . Specific cutting plates have specific reference numerals which are described further below. The cutting plates  40  are removable from the jaws  23  for maintenance and replacement and/or repositioning. It is the movement of cutting plates  40  on different jaws  23  moving past each other which create the shearing or cutting action. The cutting plates  40  are subject to a high amount of wear and for this reason, in some optional embodiments, they are removable in order to be replaced, repositioned, or for maintenance. 
         [0025]    The side cutting plates  42  are located on the movable jaw  28 . An end cutting plate  44  is located at an end or tip of the fixed jaw  26 . The movable jaw  28  also has a left tip cutting plate  46  and a right tip cutting plate  48 . The fixed jaw  26  may also be equipped with a small right side cutting plate  50  and more left side cutting plates  52 . Attaching plates  53  are also located on the fixed jaw  26 . The attaching plates  53  will be described in further detail below. 
         [0026]      FIG. 3  is an exploded view of some of the components associated with a shear  18 . The fixed jaw  26  and movable jaw  28  are not illustrated in order to avoid overcrowding of the FIG. Bolts  54  having threaded portions  56  are used with washers  58  to attach the cutting plates  42  to the jaws  23 . The cutting plates  40  have holes  60  located in them to facilitate attaching the cutting plates  40  via the bolts  54 . In some embodiments, shims  61  are used to provide a desired orientation of the cutting plates  40  when mounted onto the jaws  23 . For example, the small right side cutting plate  50  has a corresponding shim  61 . The shim  61  is equipped with slots  63  which allows the shim  61  to be positioned without moving the position of the bolts  54  within the holes  60 . In some embodiments, the holes  60  in the cutting plates  40  are threaded and thereby communicate with the threaded portions  56  on the bolts  54  to hold the bolts  54 , the shims  61  and the cutting plates  40  in place on the jaws  23 . In some embodiments, and as shown in FIG.  3 ., different shims  61  maybe used for different cutting plates  40 . For example, shims  62  correspond to the cutting plates  42  on the movable jaw  28 . A shim  64  corresponds to the end cutting plate  44 . Shims  66  are used along with the side cutting plates  52  located on the fixed jaw  26 . 
         [0027]    In addition to the cutting plates  40  attaching plates  53  may also be used to facilitate attaching the cutting plates  42  the jaws  23 . The attaching plates  53  provide a surface for the bolts  54  to compress and therefore trap the fixed jaw  26  between the cutting plates  52  and the attaching plates  53  thereby attaching the cutting plates  53  to the fixed jaw  26 . In some embodiments, as shown in  FIG. 3 , shims  68  may be used with the attaching plates  53 . The shims  68  may also include slots  63  similar to that described with respect to the other shims  61 . 
         [0028]      FIG. 3  also shows other features such as a bushing lock  70  used in positioning attaching the end cutting plate  44  to the fixed jaw  26 . 
         [0029]      FIG. 4  is a perspective view of a shear  18 . A portion of the left side cutting plate  52  on the fixed jaw  26  a portion of the fixed jaw  26  is illustrated in broken lines. This portion is enlarged as  FIG. 5 .  FIG. 5  illustrates a portion of a shear  18  in accordance with an embodiment. The shear  18  includes a cut out portion referred to as a cutting plate pocket  74 . A fixed left side cutting plate  52  is located in the cutting plate pocket  74 . A shim  66  for the left side cutting plate is located between the left side cutting plate  52  and a side wall  72  of the cutting plate pocket  74 . In some embodiments, the base  80  of the side cutting plate  52  may rest on a horizontal wall  73  of the cutting plate pocket  74 . In other embodiments, the shim  66  and/or side cutting plate  52  may be spaced from the horizontal wall  73 . The side cutting plate  52  is attached to the shear  18  by the threaded portion  56  of the bolt  54  located in the hole  60 . 
         [0030]    In the embodiment shown in  FIG. 5  the shim  66  is tapered such that the thickness of the shim at the base as shown by arrow A is thinner than the thickness at the top are the shim  66  as illustrated by arrow D. In other words, the taper may be defined by air angle θ. In some embodiments the angle θ is between 0.2 and 2 degrees. In other embodiments the angle θ is between 0.45 and 1 degree. In the figures, the angle and distances represented by the lettered arrows are exaggerated and are not drawn to scale in order to better illustrate the fact that the taper exists and the general shape of the taper. 
         [0031]    The angle or taper is passed on through the cutting plate  52  such that the cutting face  78  of the side cutting plate  52  is at approximately the same angle. When the cutting face  78  is at an angle, this is referred to as a camber. A positive camber is what is illustrated in the figures where the cutting edge  76  is located closer to the opposing jaw  23  then the rest of the cutting face  78 . If the cutting face  78  was straight up and down with respect to the opposing jaw  23 , such a position would be referred to as a mutual camber. If distance as illustrated by arrow A was greater than the distance illustrated by arrow B, then the cutting edge  76  would be farther away from the opposing jaw  23  then the rest of the cutting face  78 . This would be a negative camber. 
         [0032]    The positive camber may be accomplished, in some instances, by the cutting plate  52  having a substantially rectangular cross-section. By creating an angle or taper on the cutting face  78  a cutting edge  76  is defined. The cutting edge  76  extends farther out from the cutting plate pocket  74  then the cutting face  78  at the base  80  of the cutting plate. This provides some features. For example, when the shear  18  is compressing a workpiece within the jaws  23 , the cutting edge  76  will assist in cutting or shearing the workpiece. Further, by having the cutting face  78  in a tapered condition such that the cutting edge  76  extending toward the opposing jaw  23  than the base  80  of the cutting face  78 , the force required to move the jaws  23  past each other diminishes as the cutting edge  76  passes a corresponding cutting edge on the corresponding jaw. As result, less energy is required to move or slide the jaws  23  past each other. 
         [0033]      FIG. 6  illustrates a partial end view of a shear  18  according to another embodiment. In contrast to the embodiment shown in  FIG. 5 , the embodiment shown in  FIG. 6  has does not use a shim  61  to impart a taper to the cutting face  78 . Rather the vertical wall  72  of the cutting plate pocket  74  not truly vertical but is tapered. The distance from vertical is illustrated by arrow C. It can also be expressed by an angle which starts at the intersection of the vertical wall  72  and the horizontal wall  73  of the cutting plate pocket  74 . The angle θ may be the same as described above. Namely, in some embodiments the angle is between 0.2 and 2 degrees. In other embodiments is between 0.45 and 1 degree. The cutting-edge  76  extends farther out toward the opposing jaw  23  (not shown in  FIG. 6 ) than any other portion of the cutting face  78 . To accomadate the taper in the wall  72 , the horizontal wall  73  may also be tapered in order to allow the generally rectangular cutting plate  40  to reside in cutting plate pocket  74  at a desired camber. 
         [0034]    No shims  61  are used in the embodiment shown in  FIG. 6 . However in other embodiments shims  61  maybe used. The taper to the cutting face  78  is provided by the taper of the vertical wall  72 . In other embodiments, the taper of the cutting face  78  may be a result of a tapered shim  61  and a tapered vertical wall  72 . In the embodiment shown in  FIG. 6 , the cutting plate  40  is substantially rectangular in cross-section. As result, whatever taper occurs at the vertical wall  72  is translated to the cutting face  78 . The cutting plate  40  is attached to the shear  18  via the threaded portion  56  of the bolt  54 . The bolt  54  may also enter the cutting plate at an angle to more easily allow different cutting plates  40  to be installed in the cutting plate pocket  74 . The base  80  of the cutting plate  40  may be in contact with the horizontal wall  73  of the cutting plate pocket  74  or the base  80  may be spaced from the horizontal wall  73  of the cutting plate pocket  74  depending on the individual requirements of a given situation. 
         [0035]      FIG. 7  illustrates an opposing jaw  23  to the jaw  23  shown in  FIG. 6 . This jaw  23  may be a movable jaw  28 . Similar to the embodiment shown in  FIG. 6 , the wall  72  of the cutting plate pocket  74  provides a taper and the wall  73  is also tapered to accomade the generally rectangular cross-section of the cutting plate  40 . As result, the distance illustrated by arrow D from the location of the horizontal wall  73  from an actual horizontal line illustrated by dashed line gets longer the farther one moves from the horizontal wall  73 . Another way to express the taper is by an angle θ. In some embodiments the angle θ is between 0.2 and 2 degrees. In other embodiments the angle is between 0.45 and 1 degree. The cutting plate  40  is attached to the jaw  23  by the threaded portion  56  of the bolt  54 . The base portion  80  of the cutting plate  40  may or may not contact the horizontal wall  73  of the cutting plate pocket  74 . As described with respect to the previous figures, the cutting edge  76  extends furthest towards an opposing jaw  23  farther than any other part of the cutting face  78 . 
         [0036]    In the embodiments shown and described in  FIGS. 5 through 7  the cutting plates  40  have a substantially right angular cross-section and therefore translate any taper as result of the shim  61  or cutting plate pocket  74  to the cutting face  78 . The fact that the cutting plates  40  are substantially rectangular in cross-section allows the cutting plates to be rotated in position or between various positions once the cutting edge  76  are cutting face  78  starts to exhibit signs of undesired amounts of wear. 
         [0037]    In the embodiment shown in  FIGS. 8 and 9  the cutting plates  40  are generally not rectangular in cross-section but are tapered.  FIGS. 8 and 9  will now be described as they are opposing jaws  23  according to another embodiment. The cutting plates  40  are attached to the jaws  23  via the threaded portions  56  on the bolts  54 . In the embodiment shown in  FIGS. 8 and 9 , the cutting plate pockets  74  are generally squared cross-section. In other words, the vertical wall  72  and the horizontal wall  73  lead at substantially a right angle. However the cutting plates  40  themselves are tapered as illustrated by arrows E and F. Arrows E and F illustrate a position of the cutting face  78  with respect to actual horizontal line represented by the dashed line. This is also be represented by angle θ. In some embodiments the angle θ is between 0.2 and 2 degrees. In other embodiments is between 0.45 and 1 degree. The cross-section of the cutting plate  40  is such that the cutting plate  40  is more narrow at the base  80  then is at the other end defining the cutting edge  76 . The base  80  may contact or be spaced from the horizontal wall  73  of the cutting pocket  74 . The base  80  may also contact or be spaced from the vertical wall  72  of the cutting pocket  74 . While shims  61  are not illustrated in the  FIGS. 8 and 9  they may optionally be used. 
       INDUSTRIAL APPLICABILITY 
       [0038]    The present disclosure is applicable to shears of all sizes and uses. While the present application is directed primarily to heavy-duty hydraulic shears  18  aspects according to the disclosure may be applicable to any type of shear. By providing a cutting edge  76  that extends toward an opposing shear jaw  23  and a cutting face  78  that is tapered from the cutting edge  76  away from the opposing shear jaw  23 , a shear  18  may work more reliably in cutting or shearing materials. Furthermore, less force may be required to move for slide the shear jaws  23  past each other once the two cutting edges  76  on the two share jaws  23  have moved past each other because the cutting faces  78  will be farther from each other as the shear jaws  23  close. 
         [0039]    The amount of the taper of the shear faces (also referred to as camber) may vary per application. However one of ordinary skill the art will understand that providing too much camber may result in a cutting edge  76  that wears to quickly and providing not enough of a camber may result in a lack of the benefit from the apparatus described herein.