Abstract:
An abrasion resistant metal earth working surface having a plurality of spaced hollow open ended cup-shaped abrasion resistant studs welded to the surface which collect particulate material in the hollow open ends of the weld studs, wherein the particulate material forms an abrasion resistant barrier limiting abrasion of the earth working surface. The size and shape of the cup-shaped weld studs and the spacing between the array of studs is selected to provide optimum collection of particulate material which reduces wear to extend the efficient operation and life of the earth working surface.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. Provisional Application Serial No. 60/363,060, filed Mar. 11, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to an abrasion resistant earth working surface useful for various earth working implements or tools including, but not limited to, dozer blades, evacuation and backhoe buckets, grinders and the like, subject to abrasion and an open ended hollow abrasion resistant weld stud.  
         BACKGROUND OF THE INVENTION  
         [0003]    There are numerous earth working implements and tools having a metal surface subject to abrasive wear from sand, rocks and the like. As used herein, the term “earth working” includes an implement or tool having metal surfaces subject to abrasion, including buckets, blades, grinders, etc. used in the construction, road building and mining industries, for example. Various methods have been utilized to renew such surfaces subject to abrasion including for example arc welding a consumable electrode onto the worn metal surfaces, thermal or plasma spraying a metal surface over the worn surface and the like. Wear strips have also been utilized which may be secured by weld studs or welded onto the metal surfaces subject to wear such as disclosed, for example, in U.S. Pat. No. 4,129,952.  
           [0004]    The prior art has also proposed various methods of reducing wear or abrasion of metal earth working surfaces including welding an array of cast abrasion resistant studs onto the metal surfaces such as disclosed in U.S. Pat. No. 4,547,985. However, such cast abrasion resistant studs are similarly subject to abrasive wear or breakage during use.  
           [0005]    The need therefore remains for an improved abrasion resistant earth working surface and weld stud which effectively shields the surfaces of an earth working tool or implement during use.  
         SUMMARY OF THE INVENTION  
         [0006]    The abrasion resistant metal earth working surface of this invention includes a plurality of spaced hollow open ended abrasion resistant studs welded to the earth working surface which collect particulate material in the hollow open end of the abrasion resistant studs, forming an abrasion resistant barrier over the studs and the metal earth working surfaces. In the preferred embodiment, the abrasion resistant studs have a length measured from the earth working surface less than about one inch, limiting breakage of the studs and the studs are closely spaced on the earth working surface a distance which promotes collection of particulate material between the studs, thereby providing an abrasion barrier of particulate material covering the earth working surface. As set forth above, the metal earth working surface may be any implement or tool having a metal surface subject to abrasion from earth, sand, rocks and the like, including but not limited to buckets, blades, grinders, etc. used for example by the construction, road building and mining industries, but is not limited to such applications. The drawings illustrate, as an example only, an excavator bucket having a plurality of closely spaced hollow open ended abrasion resistant studs welded to the metal surfaces of the excavator bucket which collect particulate material including earth, sand, small rocks, dirt and other particulate material forming an abrasion barrier of the particulate material limiting wear of both the earth working surfaces and the abrasion resistant hollow studs.  
           [0007]    In one preferred embodiment of the abrasion resistant metal earth working surface of this invention, the abrasion resistant studs are spaced on the metal earth working surface a distance 1.5 and six times the diameter of the abrasion resistant studs, such that the particulate material also collects on the metal earth working surface between the studs forming a protective abrasion resistant layer of particulate material protecting the previously exposed metal earth working surface or surfaces. In the disclosed embodiment, the abrasion resistant studs each have a diameter of about one inch or less and the internal diameter of the opening through the hollow open end is equal to one-third the external diameter of the studs or greater or preferably about one-half the external diameter of the studs. In one preferred embodiment, the body portion of the studs includes a cylindrical body portion having a cylindrical opening through the distal end and a generally flat proximal end having a projecting preferably conical flux tip formed of aluminum or other suitable flux. That is, the abrasion resistant weld studs are cup-shaped to collect particulate material following welding to the metal earth working surface.  
           [0008]    In one preferred embodiment, the abrasion resistant studs have a diameter of about one inch or less and the inside diameter of the cylindrical opening is at least one-third the diameter of the body portion or preferably at least one-half or greater than the external diameter of the body portion. Thus, the studs are preferably spaced on the metal earth working surface a distance between centers of less than about twice the diameter of the abrasion resistant studs assuring collection of the particulate material between the studs forming a protective abrasion resistant barrier of the metal earth working surface and the cup-shaped studs. As set forth below, the abrasion resistant studs of this invention may be formed of various material including ferrous and non-ferrous alloys. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a partial top perspective view of a conventional excavator bucket, wherein the internal metal earth working surfaces are protected with the abrasion resistant studs of this invention;  
         [0010]    [0010]FIG. 2 is a side perspective view of one embodiment of an abrasion resistant stud of this invention;  
         [0011]    [0011]FIG. 3 is a side cross-sectional view of the abrasion resistant stud shown in FIG. 2 following welding to a metal earth working surface; and  
         [0012]    [0012]FIG. 4 is a side cross-sectional view of the excavator bucket shown in FIG. 1 during use illustrating the abrasion barrier provided by the abrasion resistant metal earth working surface of this invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    [0013]FIG. 1 is a partial elevation of a conventional excavator bucket  20  having a plurality of digger teeth  22 . As will be understood by those skilled in this art, the excavator bucket  20  and digger teeth  22  each have a plurality of metal earth working surfaces  24  which are subject to wear during use from earth, sand, rocks and other particulate material. However, in the disclosed embodiment of this invention, the metal earth working surfaces  24  include a plurality or array of abrasion resistant cup-shaped weld studs  26  which provide an abrasion resistant barrier as described below.  
         [0014]    [0014]FIG. 2 illustrates one preferred embodiment of the abrasion resistant cup-shaped weld studs  26 , wherein each of the weld studs include a body portion having a cylindrical external surface  28 , an open end  30  including an opening or cavity  32  as shown in FIG. 3 having a cylindrical inner surface  34 , a base portion  36 , as shown in FIG. 2, having a flat or generally flat bottom surface  38 , an arcuate surface  40  intermediate the cylindrical external surface  28  and the flat bottom surface  38  and the bottom surface  38  includes a generally conical flux  42 . The abrasion resistant weld stud is also unique because the cylindrical bore  32  permits the use of an internal male chuck during welding. As will be understood by those skilled in this art, the preferred flux  42  will depend upon the alloy selected for the weld stud  26 . In a typical application, the weld flux  42  will be formed of aluminum, or an aluminum alloy, wherein an opening or bore (not shown) is formed in the bottom surface  38  of the base portion  36  and the flux  42  is deformed into the opening retaining the flux  42  to the base portion  36  of the weld stud  26 . The weld studs  26  are then stud welded to the earth working surfaces  24  by drawing an electric arc between the flux  42  and the metal earth working surface  24 , melting the flux  42  and the opposed metal surface  24 . The weld studs  26  are then “plunged” into the molten metal, forming a weld  44  as shown in FIG. 3, securely retaining the abrasion resistant studs  26  to the earth working surfaces  24  of the excavator bucket  20 .  
         [0015]    [0015]FIG. 4 illustrates the excavator bucket  20  during use, wherein the abrasion resistant cup-shaped weld studs  26  retain an abrasion resistant barrier of particulate material  32  protecting the earth working surfaces  24 . During use, the cup-shaped wear resistant weld studs  26  collect particulate material  46  in the openings or cavities  32  of the studs  26  and the particulate material  46  then provides an abrasion resistant barrier overlying the weld studs  26  and the earth working surfaces  24  between the weld studs  26  as shown in FIG. 4. As will be understood from the above description, the length “L” of the weld studs  26  should be selected to avoid undue stress and breaking of the weld  44  during use of the excavator bucket. Further, the distance “D” between adjacent weld studs  26  should be selected to assure collection of particulate material  46  between the weld studs  26  covering the earth working surfaces  24  as shown in FIG. 4. Finally, the diameter of the weld studs  26  and particularly the opening or cavity  32  should also be selected to assure collection of the particulate material  46 . Based upon testing, the length “L” of the weld studs  26  should not be greater than about one inch and preferably the length should be between 0.5 and one inch.  
         [0016]    The outer diameter of the cylindrical external surface  28  is also preferably less than about one inch or more preferably between ¾ and ⅝ inches, wherein the inside or inner diameter of the cylindrical inner surface  34  is at least one-third and preferably about one-half the external diameter or greater, providing a rugged wear resistant stud having a sufficient cavity  32  to assure collection of particulate material normally encountered by earth working tools or apparatus of the type described. The distance “D” between adjacent weld studs  26  should be between 1.5 and six times the diameter of the weld studs or more preferably between 1.5 and four times the diameter measured between the center axis of the weld studs as shown in FIG. 4. An array of weld studs  26  having these dimensions has been found to be particularly suitable for this application and assures an abrasion resistant barrier of particulate material  46  as shown in FIG. 4.  
         [0017]    The material of the abrasion resistant weld studs  26  should be selected to reduce abrasive wear of the weld studs and may include ferrous or non-ferrous alloys preferably having a hardness of greater than about 40 Rockwell or more, preferably about 50 Rockwell on the C scale. Suitable ferrous alloy steels include 4037 steel, 8620 steel, 1527 steel, etc., wherein the ferrous alloy may include carbon, manganese, chromium, vanadium, molybdenum, nickel and other elements. Depending upon the material selected, the alloy may need to be heat treated to provide optimum abrasion resistance. The weld studs  26  may be formed by conventional cold forming techniques wherein the cavity  32  may be formed by back extrusion over a pin and may include a cone shaped end well, not shown.  
         [0018]    As set forth above, the abrasion resistant metal earth working surface and weld stud of this invention may be utilized in any earth working tool or apparatus having metal surfaces subject to abrasion, including but not limited to bulldozer and excavator blades and buckets, excavators, crushers, grinders, etc. and thus is not limited to a particular application. Further, as will be understood by those skilled in this art, various modifications may be made to the abrasion resistant metal earth working surface and abrasion resistant stud of this invention within the purview of the appended claims. For example, the size, shape and spacing of the array of studs on the earth working surface may be selected for a particular application, such as digging or plowing relatively soft earth having a high abrasive sand content, wherein larger studs may be selected or smaller studs may be selected for impeller blades of a grinder or crusher. Having described a preferred embodiment of the abrasion resistant metal earth working surface and abrasion resistant stud of this invention, the invention is now claimed, as set forth below.