Abstract:
A piercing tip assembly has two piercing tips, each having two sets of piercing and shearing edges. The tip is reversible so that the tip can be detached from the shears, its orientation changed, and replaced on the shears so a fresh, sharp set of piercing and shearing edges is exposed during use. The tips are reverse by rotating each tip and replacing the tip mounted on the right side of the jaw, and switching the tip on the left side of the jaw to the right side, and the tip on the right side of the jaw to the left side. The piercing tip assembly protects a substantial portion of the upper jaw of a metal shears from wear.

Description:
This application claims priority to provisional U.S. Patent Application No. 60/827,212, filed Sep. 27, 2006. 
    
    
     TECHNICAL FIELD 
     The field of this disclosure is powered jaws for shearing or crushing, such as metal shears adapted for mounting on a hydraulic excavator machine for shearing metal, and the removable cutting and piercing elements that are mounted thereon. 
     BACKGROUND 
     Metal shears and other similar tools may feature bolt-on piercing tips. In metal shears, the piercing tip is a portion at the distal end of the upper or lower jaw of the shear. The piercing tip often experiences a high rate of wear because of the difficult duty it performs in harsh environments. The wear can cause the piercing tip to lose sharpness, which results in more difficult penetration and shearing. The increased difficulty causes the shear to work harder, requiring more energy and lengthening cycle times, which ultimately can reduce the overall efficiency of the shear. 
     When the piercing tip wears and loses sharpness, it is advantageous to replace the tip. This is facilitated if the piercing tip components are attached to the shear with bolts or other mechanical fasteners. Bolt-on piercing tips have been proposed and implemented on metal shears, and facilitate replacing a dull tip for a sharp one. For example, a bolt-on piercing tip is disclosed in U.S. Patent Application Publication No. 2005/0091852 A1, published on May 5, 2005 (“the &#39;852 publication”). The piercing tip disclosed therein can be removed from the shear jaw by removing the bolts that hold it in place, and replaced with a fresh, sharp tip. 
     The &#39;852 publication also discloses a piercing tip with multiple shearing edges so the tip can be used more than once. The piercing tip disclosed therein can be detached from the shear jaw, rotated 180 degrees, and replaced on the same side of shear jaw to expose a fresh, sharp shearing edge for use. 
     However, the piercing tip in the &#39;852 publication still leaves room for improvement. The piercing tip must also protect the jaw of the shear from wear as much as possible. The geometry of the jaw and piercing tip must also resist the forces on the tip during use, without yielding or excessively fatiguing the steel. 
     SUMMARY 
     A shear tip for a metal shears may comprise a central portion joining two distal cutting portions, the two cutting portions each having a piercing edge and a shearing edge, and a plane of symmetry defined by the central portion and two cutting portions and passing through the central portion, where the two cutting portions are symmetrical about the plane of symmetry. 
     A shear tip for a metal shears may also comprise a central portion joining two distal cutting portions, the two cutting portions each having a piercing edge and a shearing edge, and the central portion and the two cutting portions forming a generally planar outside surface which is “bowtie” shaped. 
     A set of two piercing tips for a metal shears may comprise a first piercing tip having a central portion joining two distal cutting portions, the two cutting portions each having a piercing edge and a shearing edge, a second piercing tip having a central portion joining two distal cutting portions, the two cutting portions each having a piercing edge and a shearing edge, and wherein the first piercing tip is a mirror image of the second piercing tip. 
     Metal shears may comprise a jaw assembly having at least one jaw, a first piercing tip mounted to a left side of the jaw, a second piercing tip mounted to a right side of the jaw; and wherein the first and second piercing tips may be reversed by the first piercing tip being removed and replaced in the position of the second piercing tip, and the second piercing tip being removed and replaced in the position of the first piercing tip. 
     Metal shears may also comprise a jaw assembly having at least one jaw, at least one piercing tip mounted on a side of the jaw, the piercing tip including a pair of cutting portions each having a piercing edge, a pocket formed on the jaw for receiving one of the cutting portions, the cutting portion received in the pocket being an active cutting portion, and a through slot formed in the jaw for receiving the other of the cutting portions, the cutting portion received in the through slot being an inactive cutting portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the upper jaw of a metal shears with left and right side bolt-on piercing tips. 
         FIG. 2  is an assembled view of the upper jaw and bolt-on piercing tips of  FIG. 1 . 
         FIG. 3  is another assembled view like  FIG. 2 , taken from a different angle and showing the right side of the jaw rather than the left side. 
         FIG. 4  is a partially assembled view of the jaw of  FIG. 1 , with only the right side bolt-on piercing tip attached. 
         FIG. 5  is a close-up view of the right side of the jaw of  FIG. 1 , revealing the mounting location where the right side bolt-on piercing tip attaches to the jaw. 
         FIG. 6  is a perspective view of one of the bolt-on piercing tips of  FIG. 1 . 
         FIG. 7  is another perspective of one of the bolt-on piercing tips of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The following is a detailed description of exemplary embodiments of the invention. The exemplary embodiments described herein and illustrated in the drawing figures are intended to teach the principles of the invention, enabling those of ordinary skill in this art to make and use the invention in many different environments and for many different applications. The exemplary embodiments should not be considered as a limiting description of the scope of patent protection. The scope of patent protection shall be defined by the appended claims, and is intended to be broader than the specific embodiments described herein. 
       FIG. 1  is an exploded view of a shear upper jaw assembly  100  incorporating a piercing tip assembly  200 . The piercing tip assembly  200  is mechanically attached to the upper jaw assembly  100 , for easy removal and changing of the tips. The tips in the piercing tip assembly  200  are reusable, having two distinct sets of piercing edges. The tips can be reversed by changing them from a first position to a second position, exposing a fresh set of piercing edges, so that each tip can be used twice before replacement. In the illustrated embodiment, the tips in the piercing tip assembly  200  are mirror images of one another, so the costs of development and production of different left and right versions of the tips are avoided. The piercing tip assembly  200  also provides a high level of protection for the upper jaw assembly  100 , covering a large portion of surfaces that would otherwise be subject to wear during use of the shear. 
     In the illustrated embodiment, the piercing tip assembly  200  comprises two mirror image piercing tips  210 . For simplicity in explanation, the two separate tips  210  will be described by referring to only one of the tips. 
     With reference to  FIG. 1 , and  FIGS. 6 and 7  which show a tip  210  by itself, the tip  210  comprises a central portion  220  separating two distal cutting portions  230 . In the illustrated embodiment, the tip  210  comprises a plane of symmetry S (see  FIG. 6 ). Most of the features of tip  210 , including cutting portions  230 , are symmetrical about the plane of symmetry S, i.e. one half of tip  210  on one side of plane S is a mirror image of the other half of tip  210  on the other side of plane S. Symmetrical in this context does not require perfect symmetry of every feature. Indeed, some of the structures of piercing tip  210 , such as fastening structures, may not be symmetrical at all. Other features may still be considered symmetrical about plane S if the tip still is able to function as described herein, even though the geometry of those features is not perfectly mirrored. 
     Central portion  220  and cutting portions  230  combine to form a generally flat and smooth outside surface  211  (see  FIG. 7 ). Outside surface  211  can be described as “bowtie” shaped. The perimeter of outside surface  211  is defined by a concave pocket  212 , which is formed in the central portion  220 . Two forward edges  213  extend from the pocket  212  in the central portion  220  to each of the distal cutting portions  230 . Each of the forward edges may optionally be chamfered, as shown, so as to form two forward edges  213 . The cutting portions  230  include shearing edges  214  which intersect at one end thereof with forward edges  213  at an angle between approximately 50 and 70 degrees, or more preferably, between approximately 55 and 65 degrees, or more preferably an angle of approximately 60 degrees. The other end of shearing edges  214  intersects a pair of back edges  215  formed in the central portion  220 . The back edges intersect each other to form an obtuse angle. The outside surface  211  of tip  210  can be described as “bowtie” shaped because the width of outside surface  211  measured between the intersection of back edges  215  and the pocket  212  is less than the width measured from the intersections of back edges  215  with shearing edges  214  and the intersection of forward edges  213  with pocket  212 . 
     Central portion  220  also comprises an inside surface  221  (see  FIG. 6 ) opposite from the outside surface  211 . Cutting portions  230  are elevated from inside surface  221 , preferably at least twice the thickness of central portion  220 . Cutting portions  230  each include a piercing edge  231 . Each of the piercing edges  231  intersect a respective one of the forward edges  213  at approximately right angles. Cutting portions  230  are generally elongated in one direction, forming the piercing edges  231  on one end thereof, and fillet ends  232  at another opposite end thereof in the direction of elongation. Fillet ends  232  form a generally gradual and smooth fillet for effective load transfer to the upper jaw assembly  100 . 
       FIGS. 4 and 5  illustrate the upper jaw assembly  100  where the piercing tips  210  mount thereto. The upper jaw assembly  100  includes a central portion mounting pad  110  on each side thereof which corresponds in shape to the central portions  220  of piercing tips  210 . The upper jaw assembly  100  includes a left side central portion mounting pad  110  (shown in  FIGS. 1 and 4 ), and a right side central portion mounting pad  110  (shown in  FIG. 5 ). Each central portion mounting pad  110  may be a mirror image of the other. Each central portion mounting pad  110  has a general “bowtie” shape, similar to and defined in a similar fashion as the outside surfaces  211  of tips  210 . The central portion mounting pad  110  is recessed from the other exterior surfaces of upper jaw assembly  100  a depth approximately equivalent to the thickness of the central portions  220  of piercing tips  210 . 
     The upper jaw assembly  100  also includes a forward cutting portion receiving pocket  120  and an aft cutting portion receiving slot  130 . In the illustrated embodiment, each of the forward cutting portion receiving pocket  120  and the aft cutting portion receiving slot  130  is formed all the way through the thickness of the upper jaw assembly  100 . The forward cutting portion receiving pocket  120  includes a rear fillet  121  which generally matches the radius of fillet ends  232  of piercing tips  210 . The forward cutting portion receiving pocket  120  also defines an upper cutting surface  122  which is approximately parallel to the axis of rotation of upper jaw assembly  100  when it rotates to shear material against a lower jaw. The aft cutting portion receiving slot  130  in the illustrated embodiment comprises a through slot formed all the way through the thickness of the upper jaw assembly  100 . 
     The piercing tips  210  are received in the left and right side central portion mounting pads  110 , the forward cutting portion receiving pocket  120  and the aft cutting portion receiving slot  130  during operation of the metal shears. One set of cutting portions  230  is received in the forward cutting portion receiving pocket  120  and becomes the active set. The other set of cutting portions  230  is received in the aft cutting portion receiving slot  130  and becomes the inactive set. The piercing edges  231  and shearing edges  214  of the active set act to pierce and shear the metal held between the jaws of the metal shears. When the piercing edges  231  and shearing edges  214  of the active set become dull after a period of use, the piercing tips  210  can be reversed to move the inactive set of cutting portions  230  received in the aft cutting portion receiving slot  130 , to the forward cutting portion receiving pocket  120  to become the new active set. To reverse the piercing tips  210 , each of the right and left side tips are detached from the upper jaw assembly  100 . The tip from the right side is flipped and moved to the left side, and the tip from the left side is flipped and moved to the right side. 
     In the illustrated embodiment, the piercing tip assembly  200  comprises two separate, but mirror image piercing tips  210 , an “A” version and its negative a “B” version. This is best perceived by the view in  FIG. 1 . Also,  FIG. 6  shows the “A” version, while  FIG. 7  shows the “B” version. Both an “A” version and a “B” version of the piercing tip  210  are attached to each upper jaw assembly  100 . As described above, each of the “A” and “B” versions can be mounted to and reversed between the left and right side of the upper jaw assembly  100 . Because each “A” version is a mirror image of the “B” version, the costs of development and manufacturing are minimized. 
     Each piercing tip  210  can be mounted via mechanical fasteners such as bolts. Those of ordinary skill in this art will be able to specify an appropriate fastening system appropriate for a particular type of shear or other environmental factors. In the illustrated fastening system, two bolts  240  pass through each of the piercing tips  210 , through the upper jaw assembly  100 , and thread into the piercing tip  210  on the opposite side thereof. To accomplish this, each piercing tip  210  central portion  220  is provided with a pair of through threaded holes  222 , and a pair of through countersunk holes  223 . The countersinks  224  are formed on the outside surfaces  211  of the piercing tips  210 . The central portion mounting pad  110  of the upper jaw assembly is provided with four through holes  111  through which bolts  240  pass.  FIG. 4  shows the bolts  240  as they would be positioned when both piercing tips  210  are mounted. An advantage of this arrangement is that no threaded holes are needed in the upper jaw assembly  100 . If any of the threaded holes  222  become damaged, they are repaired easily by replacing piercing tips  210 . 
     To assist in force transfer from the piercing tips  210  to the upper jaw assembly  100 , dowel pins  250  may optionally be provided. Dowel pins  250  are received by the piercing tips  210  in blind dowel holes  225  formed on the inside surface  221  of central portion  220 . Dowel pins  250  are also received by the upper jaw assembly  100  in blind dowel holes  112 . 
     Depending upon the fastening system, any through threaded holes, through countersunk hoes, dowel holes, or the like may not be perfectly symmetrical about the plane of symmetry S. In describing the symmetry of the piercing tips  210 , the piercing tips may still considered symmetrical even though some variations may exist because of the arrangement of the fastening system structure. Likewise, in describing the mirror image relationship of the separate “A” and “B” versions of piercing tip  110  to one another, the versions may still be considered to be mirror images of one another even though some variations may exist because of the arrangement of the fastening system structure. 
     When mounted to the upper jaw assembly  100 , piercing tips  210  provide protection against wear which would otherwise degrade and shorten the life of upper jaw assembly  100 . As seen in  FIGS. 2 and 3 , the cutting portions  230  of piercing tips  210  completely cover the upper cutting surface  122 . The cutting portions  230  of each of the left side and right side piercing tips each cover about half of the upper cutting surface  122  in the illustrated embodiment. But it may also be possible to construct piercing tips  210  so that the tip on side of the jaw covers more than half the upper cutting surface  122 , and the tip on the other side less than half. The central portions  220  of piercing tips  210  also extend from the upper cutting surface  122  upwards to protect the left and right sides of upper jaw assembly  100 . 
     INDUSTRIAL APPLICABILITY 
     The piercing tip described and illustrated herein finds industrial applicability in metal shears or similar tools for shearing scrap metal and other materials, in industrial processes such as scrap recycling and demolition of structures.