Patent Publication Number: US-7712222-B2

Title: Composite utility blade, and method of making such a blade

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This patent application claims the benefit of U.S. provisional patent application Ser. No. 60/451,985, filed Mar. 5, 2003, entitled “Composite Utility Knife Blade, And Method Of Making Such A Blade”. The foregoing patent application is assigned to the Assignee of the present invention and is hereby expressly incorporated by reference as part of the present disclosure. 

   FIELD OF THE INVENTION 
   The present invention relates to utility blades, and more particularly, to composite utility blades wherein the outer cutting edge of the blade is made of a highly wear-resistant alloy, and a backing portion of the blade is made of an alloy selected for toughness, such as spring steel. The present invention also relates to methods of making such composite utility blades. 
   BACKGROUND INFORMATION 
   Conventional utility blades are made of carbon steel and define a back edge, a cutting edge located on an opposite side of the blade relative to the back edge, and two side edges located on opposite sides of the blade relative to each other and extending between the back and cutting edges of the blade. A pair of notches are typically formed in the back edge of the blade for engaging a locator in a blade holder. Typically, the back, cutting and side edges of the blade define an approximately trapezoidal peripheral configuration. However, prior art utility blades have been commercially available for many years in a variety of shapes other than trapezoidal, such as rectangular or hooked blades. In addition, prior art utility blades have been provided in snap-off configurations wherein a single blade includes axially spaced score lines and separable blades or blade segments therebetween. 
   Conventional utility blades are manufactured by providing a carbon steel strip, running the strip through a punch press to punch the notches at axially spaced locations on the strip, and stamping a brand name, logo or other identification thereon. Then, the strip is scored to form a plurality of axially spaced score lines, wherein each score line corresponds to a side edge of a respective blade and defines a preferred breaking line for later snapping the scored strip into a plurality of blades. The punched and scored strip is then wound again into a coil, and the coil is hardened and tempered. The hardening and tempering operations may be performed in a “pit-type” vacuum furnace wherein the coils are repeatedly heated and cooled therein. Alternatively, the hardening and tempering operations may be performed “in-line”, wherein the strip is unwound from the coil and successively driven through a series of furnaces and quenching stations to harden and temper the strip. The carbon steel strip is typically heat treated to a surface hardness of about 58 Rockwell “c” (“Rc”), and thus defines a relatively hard and brittle structure. 
   The heat treated strip is then ground, honed and stropped in a conventional manner to form the facets defining a straight cutting edge along one side of the strip. Then, the strip is snapped at each score line to, in turn, break the strip along the score lines and thereby form from the strip a plurality of trapezoidal or other shaped utility blades. Because the entire strip is relatively hard and brittle (about 58 Rc), the strip readily breaks at each score line to thereby form clean edges at the side of each blade. 
   One of the drawbacks associated with such conventional utility blades is that each blade is formed of a single material, typically carbon steel, which is heat treated to a relatively hard and brittle state, typically about 58 Rc. Thus, although such blades define a relatively hard, wear-resistant cutting edge, the entire blade is also relatively brittle, and therefore is subject to premature breaking or cracking in use. In addition, the cutting edges of such conventional blades are frequently not as wear resistant as might otherwise be desired. However, because the entire blade is made of the same material, any increase in hardness, and thus wear resistance of the cutting edge, would render the blade too brittle for practical use. As a result, such conventional utility blades are incapable of achieving both the desired wear resistance at the cutting edge, and overall toughness to prevent cracking or premature breakage during use. Another drawback of such conventional utility blades is that the carbon steel typically used to make such blades corrodes relatively easily, thus requiring premature disposal of the blades and/or costly coatings to prevent such premature corrosion. 
   Certain prior art patents teach composite utility blades defining sandwiched, laminated, or coated constructions. For example, U.S. Pat. No. 4,896,424 to Walker shows a utility knife having a composite cutting blade formed by a body section  16  made of titanium, and a cutting edge section  18  made of high carbon stainless steel and connected to the body section by a dovetail joint  25 . 
   U.S. Pat. Nos. 3,279,283, 2,093,874, 3,681,846, and 6,105,261 relate generally to laminated knives or razor blades having cutting edges formed by a core layer made of a high carbon steel or other relatively hard material, and one or more outer layers made of relatively softer materials. Similarly, U.S. Pat. Nos. 3,911,579, 5,142,785, and 5,940,975 relate to knives or razor blades formed by applying a relatively hard carbon coating (or diamond like coating (“DLC”)) to a steel substrate. In addition, U.S. Pat. Nos. 5,317,938 and 5,842,387 relate to knives or razor blades made by etching a silicon substrate. 
   One of the drawbacks associated with these laminated, sandwiched and/or coated constructions, is that they are relatively expensive to manufacture, and therefore have not achieved widespread commercial use or acceptance in the utility blade field. 
   In stark contrast to the utility blade field, bi-metal band saw blades have been used in the saw industry for many years. For example, U.S. Reissue Pat. No. 26,676 shows a method of making bi-metal band saw blades wherein a steel backing strip and high speed steel wire are pre-treated by grinding and degreasing, and the wire is welded to the backing strip by electron beam welding. Then, the composite band stock is straightened and annealed. The sides of the annealed stock are then dressed, and the band saw blade teeth are formed in the high speed steel edge of the composite stock by milling. Then, the teeth are set and the resulting saw blade is heat treated. There are numerous methods known in the prior art for heat treating such band saw blades. For example, International Published Patent Application No. WO 98/38346 shows an apparatus and method for in-line hardening and tempering composite band saw blades wherein the blades are passed around rollers and driven repeatedly through the same tempering furnace and quenching zones. The heat treated composite band saw blades are then cleaned and packaged. 
   Although such bi-metal band saw blades have achieved widespread commercial use and acceptance over the past 30 years in the band saw blade industry, there is not believed to be any teaching or use in the prior art to manufacture utility blades defining a bi-metal or other composite construction as with bimetal band saw blades. In addition, there are numerous obstacles preventing the application of such band saw blade technology to the manufacture of utility blades. For example, as described above, conventional utility blades are manufactured by forming score lines on the carbon steel strip, and then snapping the strip along the score lines to break the strip into the trapezoidal or other shaped blades. However, the relatively tough, spring-like backing used, for example, to manufacture bi-metal band saw blades, can be relatively difficult to score and snap in comparison to conventional carbon steel utility blades. In addition, the heat treating applied to conventional utility blades could not be used to heat treat bimetal or other composite utility blades. 
   The high speed or tool steels used to manufacture wear-resistant cutting edges, such as the wear-resistant cutting edges in prior art band saw blades, are relatively expensive in comparison, for example, to the carbon steels used to manufacture conventional utility blades. In addition, the grinding and honing operations involved in forming wear-resistant cutting edges from high speed and tool steels can create significant amounts of scrap and/or waste of these expensive materials. 
   Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and disadvantages of prior art utility blades and/or methods of making such blades, and to provide a bi-metal or other composite utility blade defining a relatively hard, wear-resistant cutting edge, and a relatively tough, spring-like backing, and a method of making such utility blades. 
   SUMMARY OF THE INVENTION 
   One aspect of the present invention is directed to a composite utility blade comprising a back edge, a cutting edge located on an opposite side of the blade relative to the back edge, and two side edges located on opposite sides of the blade relative to each other and extending between the back and cutting edges of the blade. In one embodiment of the present invention, the back, cutting and side edges of the blade define an approximately trapezoidal peripheral configuration. However, the blades of the present invention may take any of numerous different shapes and configurations, including rectangular, hooked, and snap-off blades. The composite utility blade of the present invention further defines first and second metal portions, wherein the first metal portion extends between the back edge and the second metal portion, and further extends from approximately one side edge to the other side edge of the blade. The first metal portion is formed of an alloy steel heat treated to a first hardness that is preferably within the range of approximately 38 Rc to approximately 52 Rc. The second metal portion defines the cutting edge, and extends from approximately one side edge to the other side edge, and is formed of a high speed or tool steel heat treated to a second hardness that is greater than the first hardness, and preferably within the range of approximately 60 Rc to approximately 75 Rc. A weld region of the blade joins the first and second metal portions and extends from approximately one side edge to the other side edge of the blade. 
   Another aspect of the present invention is directed to a method of making composite utility blades. In accordance with one embodiment of the present invention, the method comprises the steps of providing an elongated wire formed of high speed or tool steel, and an elongated backing strip formed of an alloy steel and defining an approximately planar upper side, an approximately planar lower side, and opposing back and front edges extending between the upper and lower sides. The wire is butt joined to the front edge of the backing strip. Then, thermal energy is applied to the interface between the wire and backing strip to weld the wire to the backing strip and, in turn, form a composite strip defining a first metal portion formed by the steel backing strip, a second metal portion formed by the high speed steel wire, and a weld region joining the first and second metal portions. The composite strip is then annealed, and the annealed strip is straightened to eliminate any camber or other undesirable curvatures in the annealed composite strip. Then, a plurality of notches are formed, such as by punching, in axially spaced locations relative to each other along the back edge of the first metal portion and/or at other desired locations of the annealed composite strip. The annealed and punched composite strip is then hardened such that the first metal portion defines a first surface hardness that is preferably within the range of approximately 38 Rc to approximately 52 Rc, and the second metal portion defines a second surface hardness greater than the first surface hardness, and preferably within the range of approximately 60 Rc to approximately 75 Rc. The hardened strip is then subjected to at least one, and preferably two, tempering and quenching cycles. Then, facets are formed on the edge of the second metal portion, such as by grinding, honing and stropping, to in turn form an approximately straight, high speed or tool steel cutting edge along the side of the composite strip opposite the back edge of the first metal portion. The composite strip is then die cut, bent and/or snapped, or otherwise separated along shear or score lines axially spaced relative to each other to form a plurality of utility blades from the strip. In a currently preferred embodiment of the present invention, each utility blade defines an approximately trapezoidal peripheral configuration and at least one notch is formed in the back edge thereof. However, the blades of the present invention may take any of numerous different shapes and configurations, including rectangular, hooked, and snap-off blades. 
   In accordance with an alternative embodiment of the present invention, prior to hardening, the high speed or tool steel edge of the composite strip is cut to form notches, such as by punching, at the interface of each shear or score line and the second metal portion. The notches are formed to separate the high speed steel cutting edges of adjacent composite utility blades formed from the composite strip, to facilitate bending and snapping the blades from the composite strip, and/or to shape the corners of the cutting edges of the blades. 
   In accordance with another embodiment of the present invention, the composite strip is scored at axially spaced locations relative to each other to form a plurality of score lines, wherein each score line is oriented at an acute angle relative to the back edge of the first metal portion, and the plurality of score lines define a plurality of blade sections and scrap sections located between the blade sections. In the trapezoidal blade configuration, the scrap sections are approximately triangular and the blade sections are approximately trapezoidal. As described above, notches are preferably formed at the interface of each score line and the second metal portion to facilitate separation of the blades from the composite strip and to shape the corners of the cutting edges of the blades. In order to separate the blades from the composite strip, each scrap section is bent outwardly relative to a plane of the composite strip on one side of a respective score line. Upon bending each scrap section, the composite strip is pressed on an opposite side of the respective score line to, in turn, break the blade section away from the bent scrap section along the respective score line. This process is repeated at each score line, or is performed substantially simultaneously for each pair or other group of score lines defining each respective utility blade, to thereby form the plurality of blades from the composite strip. 
   In accordance with another aspect, the present invention is directed to a method of making a composite utility blade. The blade includes a first metal portion forming a backing, a second metal portion forming a cutting edge and defining a first predetermined cross-sectional shape, and a weld region joining the first and second metal portions. The method comprises the steps of: 
   (i) providing an elongated backing strip formed of steel, wherein the elongated backing strip includes a first side, a second side, and opposing edges extending between the first and second sides; 
   (ii) providing an elongated wire formed of wear-resistant steel and defining a second predetermined cross-sectional shape substantially corresponding to the first predetermined cross-sectional shape of the second metal portion of the blade; 
   (iii) placing the wire in contact with an edge of the backing strip; 
   (iv) applying thermal energy to the interface between the wire and backing strip to weld the wire to the backing strip and, in turn, forming a composite strip defining a first metal portion formed by the steel backing strip, a second metal portion formed by the wear-resistant steel wire having substantially the second predetermined cross-sectional shape, and a weld region joining the first and second metal portions; 
   (v) heat treating the composite strip; and 
   (vi) forming at least one facet on the second metal portion and, in turn, forming a wear-resistant steel cutting edge on the composite strip. 
   In one embodiment of the present invention, the step of providing an elongated wire includes providing a wire that defines an initial cross-sectional shape, and then shaping the wire into the second predetermined cross-sectional shape that is different than the initial cross-sectional shape. Preferably, the wire is shaped into the second predetermined cross-sectional shape prior to welding the wire to the backing strip. Also in one embodiment of the present invention, the initial cross-sectional shape of the wire is substantially round, and the second predetermined cross-sectional shape of the wire is multi-faceted. Preferably, the second predetermined cross-sectional shape of the wire is selected from the group including: (a) substantially rectangular; (b) substantially trapezoidal; (c) substantially triangular; (d) substantially parallelogram-shaped; and (d) a combination of substantially rectilinear and triangular. Also in currently preferred embodiments of the present invention, the step of shaping the wire into the second predetermined cross-sectional shape includes at least one of: (a) rolling the wire; (b) passing the wire through a Turks Head; and (c) passing the wire through a draw die. 
   In one embodiment of the present invention, the method further comprises the step of coating the wear-resistant cutting edge with at least one of TiN and AlTiN. In one such embodiment, the method further comprises the steps of coating the wear-resistant cutting edge with an inner layer of AlTiN and an outer layer of TiN. In one such embodiment, the method further comprises the step of applying the AlTiN coating in a gradient such that there is a lower concentration of aluminum at the inner side of the coating and a higher concentration of aluminum at the outer side of the coating. 
   In accordance with another aspect, the present invention is directed to a composite strip for forming therefrom at least one utility blade. The blade includes a first metal portion forming a backing, a second metal portion forming a cutting edge and defining a first predetermined cross-sectional shape, and a weld region joining the first and second metal portions. The composite strip comprises a first metal portion defined by an elongated backing strip formed of steel, wherein the elongated backing strip defines a first side, a second side, and opposing edges extending between the first and second sides. A second metal portion of the strip defines a second predetermined cross-sectional shape substantially corresponding to the first predetermined cross-sectional shape of the second metal portion of the blade, and is defined by an elongated wire formed of wear-resistant steel and having substantially the second predetermined cross-sectional shape. A weld region of the strip joins the first and second metal portions. 
   In one embodiment of the present invention, the second predetermined cross-sectional shape of the wire and the first predetermined cross-sectional shape of the second metal portion are selected from the group including: (a) substantially rectangular; (b) substantially trapezoidal; (c) substantially triangular; (d) substantially parallelogram-shaped; and (d) a combination of substantially rectilinear and triangular. In one such embodiment, the second predetermined cross-sectional shape of the wire is substantially the same as the first predetermined cross-sectional shape of the second metal portion of the blade. 
   In one embodiment of the present invention, the composite strip further comprises at least one of an AlTiN coating and a TiN coating. In one such embodiment, the composite strip comprises an inner AlTiN coating and an outer TiN coating. In one such embodiment, the coatings define a strip extending along opposite sides of the cutting edge relative to each other. 
   One advantage of the utility blades of the present invention, is that they provide an extremely hard, wear-resistant cutting edge, and an extremely tough, spring-like backing, particularly in comparison to the conventional utility blades as described above. Thus, the utility blades of the present invention provide significantly improved blade life, and cutting performance throughout the blade life, in comparison to conventional utility blades. In addition, the utility blades, and methods of making such blades, are relatively cost effective, particularly in comparison to the composite utility blades defining sandwiched, laminated and/or coated constructions, as also described above. As a result, the utility blades of the present invention provide a combination of wear resistance, toughness, cutting performance, and cost effectiveness heretofore believed to be commercially unavailable in utility blades. 
   Other objects and advantages of the present invention will become readily apparent in view of the following detailed description of preferred embodiments and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view of a composite utility blade embodying the present invention; 
       FIG. 2  is partial, end elevational view of the composite utility blade of  FIG. 1  showing the multi-faceted cutting edge of the blade. 
       FIGS. 3A and 3B  are flow charts illustrating conceptually the procedural steps involved in a method of making the composite utility blades in accordance with certain embodiments of the present invention. 
       FIG. 4  is a somewhat schematic, perspective view of an apparatus for welding a high speed steel wire to a spring-steel backing to form bi-metal utility blades in accordance with certain embodiments of the present invention. 
       FIG. 5  is a somewhat schematic, perspective view of an apparatus for scoring and punching bi-metal strips in order to make bi-metal utility blades in accordance with one embodiment of the present invention. 
       FIG. 6  is a somewhat schematic, perspective view of an apparatus for die cutting bi-metal strips in accordance with an embodiment of the present invention. 
       FIG. 7  is a somewhat schematic, perspective view of an apparatus for punching notches in the high-speed or tool steel edges of the bi-metal strips prior to hardening the strips in accordance with an embodiment of the present invention, and the resulting notched strip. 
       FIG. 8  is a somewhat schematic, top plan view of an apparatus for bending and snapping the composite strips in order to make the composite utility blades in accordance with another embodiment of the invention. 
       FIG. 9  is a partial cross-sectional view of the bending and snapping apparatus taken along line  9 - 9  of  FIG. 8 . 
       FIG. 10  is a side elevational view of a composite bi-metal strip that further illustrates in broken lines the bending pins and breaking punches of the bending and snapping apparatus of  FIGS. 8 and 9  that operate on the composite strip to form the composite utility blades of the present invention. 
       FIGS. 11A-11D  are top plan views of the composite utility blade of the present invention illustrating exemplary shapes and configurations that the utility blade may take. 
     FIGS.  12 A and  12 D- 12 F are cross-sectional views of additional embodiments of the composite strip of the present invention formed by welding pre-shaped high speed steel wires to the spring steel backings. 
       FIG. 12B  is a somewhat schematic, perspective view of the apparatus for welding the pre-shaped high speed steel wire to the spring steel backing of the composite strip of  FIG. 12A . 
       FIG. 12C  is a partial, perspective view of the composite strip of  FIG. 12A . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIG. 1 , a composite utility blade embodying the present invention is indicated generally by the reference numeral  10 . The utility blade  10  defines a back edge  12 , a cutting edge  14  located on an opposite side of the blade relative to the back edge, and two side edges  16 ,  18  located on opposite sides of the blade relative to each other and extending between the back and cutting edges of the blade. As shown typically in  FIG. 1 , in the illustrated embodiment of the present invention, the back, cutting and side edges of the blade preferably define an approximately trapezoidal peripheral configuration. However, as described further below with reference to  FIGS. 11A-11D , the utility blade of the present may take any of numerous different shapes or configurations that currently or later become known, including, for example, a square or parallelogram shape, and/or any desired shape with squared, rounded or oblique cutting corners. 
   The blade  10  further defines a first metal portion  20  and a second metal portion  22 . As shown typically in  FIG. 1 , the first metal portion  20  extends between the back edge  12  and the first metal portion  22 , and further extends from approximately one side edge  16  to the other side edge  18 . In accordance with the present invention, the first metal portion  20  is formed of a steel, typically referred to as an “alloy” steel, that is heat treated to a surface hardness within the range of approximately 38 Rockwell “c” (referred to herein as “Rc”) to approximately 52 Rc. The second metal portion  22  defines the cutting edge  14  and extends from approximately one side edge  16  to the other side edge  18 . In accordance with the present invention, the second metal portion  22  is formed of a steel, typically referred to as a “high speed” or “tool” steel, that is heat treated to a surface hardness within the range of approximately 60 Rc to approximately 75 Rc. 
   The first metal portion  20  defines a spring-like backing that is relatively pliable, tough, and thus highly resistant to fatigue and cracking. The second metal portion  22 , on the other hand, is relatively hard and highly wear resistant, and thus defines an ideal, long-lasting cutting blade. As a result, the composite utility blades of the present invention define highly wear-resistant, long-lasting cutting edges, combined with virtually unbreakable or shatterproof backings (and thus shatter-proof blades). Thus, in stark contrast to the typical utility blades of the prior art, the composite utility blades of the present invention provide a cost-effective blade exhibiting both improved wear resistance and toughness heretofore commercially unavailable in such blades. 
   The first metal portion  20  of blade  10  is preferably made of any of numerous different grades of steel capable of being heat treated to a surface hardness within the preferred range of approximately 38 Rc to approximately 52 Rc, such as any of numerous different alloy steels or standard AISI grades, including without limitation 6135, 6150 and D6A. The second metal portion  22 , on the other hand, is preferably made of any of numerous different types of wear-resistant steel capable of being heat treated to a surface hardness within the preferred range of approximately 60 Rc to approximately 75 Rc, including any of numerous different tool steels or high-speed steels, such as any of numerous different standard AISI grades, including, without limitation, M Series grades, such as M1, M2, M3, M42, etc., A Series grades, such as A2, A6, A7 A9, etc., H Series grades, such as H10, H11, H12, H13, etc., T Series grades, such as T1, T4, T8, etc., and W, S, O, D and P Series grades. 
   As may be recognized by those skilled in the pertinent art based on the teachings herein, the currently preferred materials used to construct the first and second metal portions  20  and  22  and disclosed herein are only exemplary, and numerous other types of metals that are currently or later become known for performing the functions of the first and/or second metal portions may be equally employed to form the composite utility blades of the present invention. 
   As further shown in  FIG. 1 , each composite utility blade  10  defines a pair of cut outs or notches  24  formed in the back edge  12  and laterally spaced relative to each other. As shown typically in  FIG. 1 , each notch  24  defines a concave, approximately semi-circular profile, and is provided to engage a corresponding locator mounted within a blade holder (not shown) in order to retain the blade in the blade holder. As may be recognized by those skilled in the pertinent art based on the teachings herein, the notches  24  may take any of numerous different shapes and/or configurations in any of numerous different locations, and the blade may include any number of such notches or other recesses that are currently or later become known to those skilled in the pertinent art for performing the function of engaging a blade holder, or the blade actuating mechanism or locator of such a holder. 
   As also shown in  FIG. 1 , the blade  10  further defines a registration aperture  26  extending through the first metal portion in an approximately central portion of the blade. As described further below, the registration aperture  26  is provided to receive a blade positioning device to position the blade in a die, in a blade bending and snapping apparatus, or other blade forming device used during the process of making the blades in accordance with the present invention. As may be recognized by those skilled in the pertinent art based on the teachings herein, the aperture  26  may take any of numerous different shapes or configurations, and the blade may include any number of such apertures or other structural features for performing the function of properly positioning the blade in a die or other manufacturing apparatus. In addition, the registration aperture(s)  26  may be located in any of numerous different locations on the utility blade, or may be located within the scrap material adjacent to the blade and within the bimetal strip from which the blade is formed. 
   As further shown in  FIG. 1 , the blade  10  defines a weld region  28  formed between the first and second metal portions  20  and  22 , respectively, and defining an approximate line of joinder extending from one side edge  16  to the other side edge  18 . As described in further detail below, the second metal portion is joined to the first metal portion  20  by applying thermal energy to the interface, such as by electron beam welding, to thereby weld the first metal portion to the second metal portion and form a resulting weld region defining a line of joinder between the two different metal portions. 
   As also shown in  FIG. 1 , the cutting edge  14  defines an approximately straight cutting edge extending from one side edge  16  to the other side edge  18 . As shown in  FIG. 2 , the cutting edge  14  preferably defines first facets  30  located on opposite sides of the blade relative to each other, and second facets  32  spaced laterally inwardly and contiguous to the respective first facets  30 . As shown typically in  FIG. 2 , the first facets  30  define a first included angle “A”, and the second facets  32  define a second included angle “B”. Preferably, the second included angle B is less than the first included angle A. In one embodiment of the present invention, the first included angle A is approximately 26° and the second included angle B is approximately 18°. However, as may be recognized by those skilled in the pertinent art based on the teachings herein, these included angles are only exemplary and may be set as desired depending upon the physical properties and/or proposed applications of the blade. As may be further recognized by those skilled in the pertinent art, the utility blades of the present invention may include any number of facets. 
   Turning to  FIGS. 3A and 3B , a method of making the composite utility blades of the present invention is hereinafter described in further detail. As shown at steps  100  and  102 , the backing steel forming the first metal portion  20  and the high speed or tool steel wire forming the second metal portion  22  are cleaned and otherwise prepared for welding in a manner known to those of ordinary skill in the pertinent art. As shown in  FIG. 4 , the backing steel is preferably provided in the form of one or more continuous elongated strips  34  wound into one or more coils. Each backing strip  34  defines an approximately planar upper side  36 , an approximately planar lower side  38 , and opposing back and front edges  40  and  42 , respectively. Similarly, the high speed steel wire is preferably provided in the form of one or more continuous lengths of wire  44  wound into one or more coils. 
   At step  104  of  FIG. 3A , the high speed or tool steel wire  44  is butt joined to the front edge  42  of the backing strip  34 , and thermal energy is applied to the interface between the wire and the backing strip to, in turn, weld the wire to the backing strip and form a bimetal or composite strip  46  defining the first metal portion  20  formed by the steel backing strip  34 , the second metal portion  22  formed by the high speed steel wire  44 , and the weld region  28  joining the first and second metal portions. As shown in  FIG. 4 , a typical welding apparatus  48  includes opposing rollers  50  laterally spaced relative to each other for butt joining the high speed steel wire  44  to the front edge  42  of the backing strip  34 , and rotatably driving the composite or bimetal strip  46  through the welding apparatus. A thermal energy source  52  is mounted within the welding apparatus  48  and applies thermal energy to the interface of the high speed steel wire  44  and front edge  42  of the backing strip to weld the wire to the backing strip. In the currently preferred embodiment of the present invention, the thermal energy source  52  transmits an electron beam  54  onto the interface of the high speed steel wire and backing strip to electron beam weld the wire to the backing strip. However, as may be recognized by those skilled in the pertinent art based on the teachings herein, any of numerous other energy sources and/or joining methods that are currently or later become known for performing the functions of the electron beam welding apparatus may be equally employed in the method of the present invention. For example, the energy source for welding the high speed steel wire to the backing strip may take the form of a laser or other energy source, and welding processes other than electron beam welding may be equally used. As described further below in connection with  FIGS. 12A through 12F , the high speed or tool steel wire  44  may be pre-shaped to define a predetermined cross-sectional shape that is the same as, or otherwise that substantially corresponds to the cross-sectional shape of the second metal portion  22 , and then the pre-shaped wire may be welded to the backing strip as described above. As also described further below, pre-shaping the wire in this manner can reduce the amount of scrap and/or waste of the high speed or tool steel wire during grinding, and further, can reduce the amount of grinding and thus can reduce the overall cost of the blades. 
   As shown at step  106  of  FIG. 3A , after welding the wire to the backing strip, the bimetal strip  46  may then be coiled for annealing and/or for transporting the strip to an annealing station. As shown at step  108 , the bi-metal strip  46  is annealed in a manner known to those of ordinary skill in the pertinent art. Typically, the bi-metal strips  46  are annealed in a vacuum furnace of a type known to those of ordinary skill in the pertinent art wherein a plurality of coils are vertically mounted relative to each other on a thermally conductive rack, and the rack is mounted in an evacuated furnace to soak the coils at a predetermined annealing temperature for a predetermined period of time. In the currently preferred embodiment of the present invention, the bimetal strips  46  are annealed at a temperature within the range of approximately 1400° F. to approximately 1600° F. for up to approximately 5 hours. Then, the heated coils are allowed to cool at a predetermined rate in order to obtain the desired physical properties. For example, the coils may be cooled within the evacuated furnace initially at the rate of about 50° F. per hour until the coils reach approximately 1000° F., and then the coils may be allowed to cool at a more rapid rate. As may be recognized by those skilled in the pertinent art based on the teachings herein, these temperatures and times are only exemplary, however, and may be changed as desired depending upon any of numerous different factors, such as the particular materials, constructions and/or dimensions of the bimetal strip  46 , the type of welding process used to weld the wire to the backing, and/or the desired physical properties of the resulting blades. 
   After annealing, the bi-metal strip  46  is then uncoiled, if necessary, as shown at step  110 , and the strip is straightened, as shown at step  112 . After welding and annealing, the bi-metal strip  46  may develop a significant camber or other undesirable curvatures, and therefore such curvatures must be removed prior to further processing. In the currently preferred embodiment of the present invention, the bimetal strip  46  is mechanically straightened by passing the strip through a series of pressurized rolls in a straightening apparatus of a type known to those of ordinary skill in the pertinent art, such as the Bruderer™ brand apparatus. However, as may be recognized by those skilled in the pertinent art based on the teachings herein, any of numerous straightening apparatus that are currently or later become known for performing the function of straightening metal articles like the bi-metal strip  46  may be equally employed. For example, as an alternative to the mechanical straightening apparatus, the bimetal strip  46  may be straightened by applying heat and tension thereto in a manner known to those of ordinary skill in the pertinent art. 
   As shown at step  114 , the straightened bimetal strip  46  may be coiled again, if necessary, for transportation and further processing. As shown at step  116  of  FIG. 3B , the annealed and straightened bi-metal strip  46  is then uncoiled, if necessary. At step  118 , the bimetal strip is punched to form a plurality of notches or other cut outs  24  axially spaced relative to each other along the back edge  40  of the annealed bi-metal strip, if desired or otherwise required, and is scored to form a plurality of score lines defining the side edges  16  and  18  of each blade. As shown in  FIG. 5 , a typical apparatus for performing the punching and scoring operations on the bi-metal strip  46  is indicated generally the reference numeral  56 . The apparatus  56  includes a scoring tool or instrument  58  mounted on a support  60  above a work support surface  62  supporting the bi-metal strip  46  thereon. As indicated by the arrows in  FIG. 5 , the scoring instrument is movable vertically into and out of engagement with the bi-metal strip, and may be movable laterally relative to the strip. Thus, as shown typically in  FIG. 5 , the scoring tool  58  is controlled to engage the upper surface  36  of the bi-metal strip and move into and/or laterally across the strip to, in turn, score the upper surface of the strip and thereby form a plurality of score lines  64  axially spaced relative to each other on the strip and each defining a side edge  16  or  18  of a respective utility blade  10  ( FIG. 1 ). As may be recognized by those skilled in the pertinent art based on the teachings herein, the scoring instrument may take any of numerous configurations that are currently, or later become known for performing the function of scoring the composite strip as described herein. For example, a progressive die may be employed to punch the registration aperture  26  for each blade. Then, the same progressive die may either simultaneously or sequentially form the notches  24 ,  98  in the back and/or cutting edges of each blade and form the score lines  64 . The term score line is used herein to mean a line defined by a recess or indentation in the surface of the composite strip. Such lines can be formed by any of numerous instruments or tools that are currently or later become known. 
   In accordance with a currently preferred embodiment of the present invention, the depth of score is preferably within the range of about 40% to about 50% of the thickness of the blade, and most preferably within the range of about 45% to about 48% of the thickness of the blade. In the illustrated embodiment, the blade is approximately 0.6 mm thick, and the depth of score is preferably within the range of about 0.27 mm to about 0.29 mm. With the current blade design and materials of construction, a depth of score greater than about 50% of the blade thickness has tended to cause the bi-metal strip to pull apart at the score lines upon passage through the furnace. Also in accordance with the currently preferred embodiment of the present invention, each score line is approximately v-shaped, and the included angle of each v-shaped score line is preferably within the range of about 50° to about 60°. In the illustrated embodiment of the present invention, the included angle of each score line is about 55°. The greater the included angle of the score line, the greater is the pressure on the back side of the blade upon scoring, and thus the greater is the likelihood that the scoring tool will create a ripple effect on the back side of the blade. The smaller the included angle, on the other hand, the more rapid will be the scoring tool wear during use. 
   The apparatus  56  further includes a punch  66  defining a plurality of cutting surfaces  68 , each corresponding in shape and position to a respective notch  24  and aperture  26 . As shown in  FIG. 5 , the punch  56  is drivingly connected to drive source  70 , such as a hydraulic cylinder, and is movable into and out of engagement with the bi-metal strip seated on the work support surface  62  for cutting the notches  24  and aperture  26  in the bi-metal strip. As will be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the scoring tool  58  and punch  66  may be computer-controlled to automatically drive the scoring tool and punch into and out of engagement with the bi-metal strip, and a driving mechanism (not shown) may be employed to automatically index the bi-metal strip relative to the scoring tool and punch. Similarly, the scoring tool and punch may be mounted in different apparatus or work stations than each other, and/or may each take the form of any of numerous other tools that are currently or later become known for either applying the score lines to the bi-metal strip, or cutting the notches and/or apertures in the bi-metal strip. For example, as described above, a progressive die may be employed to punch the registration apertures and notches and to form the score lines. In addition, as described further below, at step  118  of  FIG. 3B , the high speed or tool steel cutting edges of the blades may be notched at the juncture of each score line and the cutting edge to facilitate separation of the blades from the composite strip and to shape the corners of the cutting edges of the blades. 
   As shown at step  120  of  FIG. 3B , the punched and scored bi-metal strip  46  may be coiled again, if necessary, for either temporary storage or transportation to the hardening and tempering stations. At step  122 , the bi-metal strip is then uncoiled, if necessary, and at step  124 , the uncoiled strip is hardened and tempered. As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the hardening and tempering operations may be performed in accordance with any of numerous different hardening and tempering processes and apparatus that are currently known, or later become known for hardening and tempering articles like the bi-metal strip  46 . In the currently preferred embodiment of the present invention, the bi-metal strip  46  is hardened at a temperature within the range of approximately 2000° F. to approximately 2200° F. for a hardening time period within the range of about 3 to about 5 minutes. Then, after hardening, the bi-metal strip is tempered within a first tempering cycle at a temperature within the range of approximately 1000° F. to approximately 1200° F. for a tempering time within the range of about 3 to about 5 minutes. After the first tempering cycle, the bi-metal strip is quenched by air cooling to room temperature. In the currently preferred embodiment of the present invention, the hardening and tempering cycles are performed “in-line” such that the bi-metal strip is continuously driven first through an elongated hardening furnace, then through a first elongated tempering furnace, then through a quenching station, and then through at least one more tempering furnace and quenching station. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the bi-metal strip may be repeatedly passed through the same tempering furnace and quenching station(s), and/or may be wound into coils and hardened, tempered and quenched in a “pit-type” or other furnace. In addition, the quenching may be an air quench as described herein, or may be an oil quench or other type of quench that is currently, or later becomes known for quenching tempered articles of the type disclosed herein. Similarly, the composite strip may be subjected to any number of tempering and quenching cycles as may be required in order to obtain the desired physical characteristics of the resulting blades. 
   At step  126 , the tempered and quenched bi-metal strip  46  is coiled again, if necessary, for transportation to the next tempering station, and at step  128 , the bi-metal strip is uncoiled for the second tempering cycle. As discussed above, these and other coiling and uncoiling steps can be eliminated by providing one or more in-line stations for processing the bi-metal strip. At step  130 , the bi-metal strip is tempered again within a second tempering cycle at a temperature within the range of approximately 1000° F. to approximately 1200° F. for a tempering time within the range of about 3 to about 5 minutes. After the second tempering cycle, the bi-metal strip is quenched to room temperature. In the currently preferred embodiment, the quench is an air quench; however, as discussed above, this quench may take the form of any of numerous other types of quenching processes that are currently or later become known for articles of the type disclosed herein. Then, at step  132  the tempered and quenched bi-metal strip is coiled again either for temporary storage and/or transportation to the grinding, die cutting or bending and snapping stations. 
   At step  134 , the annealed, hardened and tempered bi-metal strip  46  is uncoiled again, if necessary, and at  136 , the bi-metal strip is subjected to grinding, honing, stropping, and die-cutting or bending and snapping steps. More specifically, the bi-metal strip  46  is ground, honed and stropped in a manner known to those of ordinary skill in the pertinent art to form the facets  30  and  32  of  FIG. 2 , and thereby define a straight, high-speed or tool steel cutting edge along the side of the composite strip opposite the back edge of the first metal portion. At this point, the ground, honed and stropped bi-metal strip  46  may be coated, such as by PVD coating the cutting edge and adjacent portions of the strip with a TiN or AlTiN coating, or with an inner coating of AlTiN and an outer coating of TiN, as described further below. Alternatively, the bi-metal strip may not be coated. The ground, honed and stropped bi-metal strip  46  (either coated or not coated) is then die cut, bent and snapped or otherwise separated along the score lines  64  of  FIG. 5  to thereby form a plurality of utility blades from the composite strip. As described above, in one embodiment of the present invention, each utility blade defines an approximately trapezoidal peripheral configuration with the notches  24  and central aperture  26  formed therein, as shown typically in  FIG. 1 , or otherwise as described below. 
   As shown in  FIG. 6 , a typical apparatus for die cutting the bi-metal strip is indicated generally by the reference numeral  72 . The apparatus  72  comprises male and female dies  74  and  76 , respectively, wherein the female die  76  is connected to a shaft  78  and the shaft is, in turn, drivingly connected to a hydraulic cylinder or like drive source  80  for moving the female die  78  into and out of engagement with the bi-metal strip  46  overlying the male die  74 . The male die  74  includes a locator pin  82  projecting upwardly therefrom and received within the apertures  26  of the bi-metal strip to thereby properly locate the bimetal strip between the male and female dies. As shown in phantom in  FIG. 6 , the female die  76  includes blade-like edges  84 , and the male die  74  includes opposing blade-like edges  86  overlying and underlying respectively the score lines  64  of the portion of the bi-metal strip  46  received between the dies. Then, in order to die cut the strip, the drive source  80  is actuated to drive the female die  76  downwardly and into engagement with the bi-metal strip such that the female and male blade-like edges  84  and  86 , respectively, cooperate to shear the bi-metal strip along the score lines and thereby form a respective utility blade embodying the present invention, as shown typically in  FIG. 1 . During this die-cutting operation, because of the relative hardness of the first and second metal portions  20  and  22 , respectively, of the bi-metal strip, the strip is sheared by the blade-like edges along the score lines  64  within the first metal portion  20 , and is snapped by the blade-like edges along the portions of the score lines within the relatively hard and brittle second portion  22 . Thus, the score lines provide desired break lines (or a desired “crack path”) within the relatively hard and brittle second metal portion, and therefore are important to providing clean and sharp edges in these regions of the blades. 
   In accordance with an alternative embodiment of the present invention, and as shown typically in  FIG. 7 , the bi-metal strip  46  may be punched prior to hardening at step  124  in order to avoid the need to later cut the relatively hard and brittle high speed steel edge at step  136 , and thereby prevent any possible damage to the cutting edge  14  and facets  30  and  32  formed thereon that might otherwise occur during die-cutting. As shown typically in  FIG. 7 , an apparatus for punching the high-speed steel edge in accordance with one embodiment of the present invention is indicated generally by the reference numeral  88 . The apparatus  88  includes a punch or like tool  90  mounted on a tool support  92  over a work support surface  94  for supporting the bi-metal strip  46  thereon. The tool support  92  is drivingly connected to a hydraulic cylinder or like drive source  96  for driving the punch  90  into and out of engagement with the high speed steel edge  14  of the bi-metal strip  46 . As shown typically in  FIG. 7 , the punch  90  is shaped and configured to form a notch  98  at the interface of each score line  64  and the high speed steel edge or second metal portion  22 . Thus, as shown typically in  FIG. 7 , each notch  98  may extend along the respective score line throughout the second metal portion  22  of the score line to thereby separate the high speed steel portion of the respective blade from the remainder of the bi-metal strip at the score lines. Alternatively, as described further below, each score line may extend along only a portion of the lateral extent of the second metal portion to facilitate cleanly separating the blades from the composite strip and/or to shape the corners of the cutting edges. Then, when the bi-metal strip  46  is die cut as shown in  FIG. 6 , or bent and snapped as described below, the equipment need only cut or snap the first metal portion  20  of the strip along the score lines and need not cut or snap the high speed steel edge portions removed by the notching operation. As described above, the first metal portion  20  is relatively pliable and significantly less hard than the second metal portion  22 , and therefore the first metal portion  20  may be easily and cleanly die cut, bent and snapped, or otherwise separated along the score lines  64 . After hardening, the second metal portion  22  may be relatively difficult to die cut because of the relative hardness and brittleness of this portion. However, prior to hardening, the high speed steel edge exhibits a surface hardness within the range of about 25 Rc, and therefore may be relatively easily and cleanly cut at this stage of the process. Accordingly, the alternative process and construction of  FIG. 7  may facilitate the ability to avoid any damage to the hardened, high speed steel edge, that might otherwise occur when die cutting such edge. 
   The notches  98  of  FIG. 7  are shown as v-shaped notches. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, these notches or cut outs may take any of numerous different shapes that may be required to separate the high speed steel edge portions of each blade from the remainder of the composite strip at the score lines. Similarly, as described further below, the notches may be formed to shape the corners of the cutting edges to be squared, oblique, or any other desired shape. As may be further recognized by those skilled in the pertinent art based on the teachings herein, it may be possible in the alternative embodiment of the present invention to eliminate the score lines because the score lines may be unnecessary in certain circumstances for purposes of die cutting the first metal portion  20  of the bi-metal strip. 
   Turning again to  FIG. 3B , at step  138  the blades are stacked, and at step  140 , the stacked blades are packaged in a manner known to those of ordinary skill in the pertinent art. 
   Turning to  FIGS. 8 and 9 , an apparatus for bending and snapping the composite strips  46  in order to form the utility blades  10  is indicated generally by the reference numeral  142 . The apparatus  142  includes a blade support  144 , a drive assembly  146  mounted on one side of the blade support, and a blade magazine  148  mounted on the opposite side of the blade support relative to the drive assembly  146 . The drive assembly  146  includes a drive plate  147  mounted on linear bearings (not shown) and drivingly connected to a suitable drive source, such as a hydraulic or pneumatic cylinder (not shown), for moving the drive plate toward and away from the blade support  144  as indicated by the arrows in  FIG. 8 . The drive assembly  146  further includes a first bending pin  150  slidably received through a first pin aperture  152  extending through the blade support  144 ; a second bending pin  154  slidably received through a second pin aperture  156  extending through the blade support; a first breaking punch  158  including a support shaft  160  slidably received through a first punch aperture  162  extending through the blade support; and a second breaking punch  164  including a support shaft  166  slidably received through a second punch aperture  168 . The first breaking punch  158  includes a first blade release pin  170 , and the second breaking punch  164  includes a second blade release pin  172 . As described further below, each blade release pin  170  and  172  is spring loaded in the direction out of the page in  FIG. 9 . Accordingly, upon bending and snapping each blade  10  from the composite strip  46 , the spring loaded pins  170  and  172  drive the respective blade  10  into the blade magazine  148 . The apparatus  142  further includes a spring-loaded presser plate  174  for pressing the composite strip  46  against the blade support  144 . The presser plate  174  is mounted on a shaft  176  slidably received through an aperture  178  formed in a support block  180  for movement toward and away from the blade support, as indicated by the arrows in  FIG. 8 . A coil spring  182  or like biasing member is coupled to the presser plate  174  and support shaft  176  to normally bias the presser plate toward the blade support. As shown in  FIG. 8 , the blade magazine  148  is spaced away from the blade support  144  to thereby define a blade gap  184  therebetween. The composite strip  46  is fed through the blade gap  184  in the direction from the right-hand to the left-hand side in each of  FIGS. 8 and 9 . The surface  186  of the blade magazine  148  facing the blade support  144  defines a rule or die against which the composite strip is pressed for performing the bending and snapping operation. 
   In  FIG. 10 , the composite strip  46  that is bent and snapped in the apparatus  142  includes registration apertures  26  formed in the scrap portion of the strip, i.e., between the score lines  64  of adjacent blades  10 . In addition, the composite strip  46  includes a plurality of notches  98  formed in the second metal portion  22  at the juncture of each score line  64  and the second metal portion. As can be seen in  FIG. 10 , each notch  98  extends laterally into the second metal portion  22  about half-way across the width of the second metal portion. In addition, the end surfaces of each notch in the axial direction of the composite strip are each oriented approximately normal to the cutting edge (i.e., each notch is approximately rectangular). In this manner, when the composite strip is bent and snapped and the blades are separated therefrom as described further below, the corners of each cutting edge  14  are squared. The depth of each notch  98  (i.e., the lateral dimension on the composite strip) is sufficient to remove from the strip the respective portion of the cutting edge  14  that does not define a score line  64 , and that contains any portion of the respective score line that is too shallow due to the sloped configuration of the facets  30 ,  32  to effectively bend and snap the blade from the strip and thereby define a clean corner (i.e., a straight edge or otherwise an edge defined by a clean break along the respective score line). Accordingly, a significant advantage of the notches  98  is that they facilitate forming a clean break at the corners of the cutting blades. In addition, by shaping the corners of the cutting edge to define a squared edge, a rounded edge, an oblique edge, or other desired shape, the corners of the blade can be made significantly more robust in comparison to pointed corners, and thus less susceptible to chipping and/or breaking in comparison to pointed corners. As may be recognized by those skilled in the pertinent art based on the teachings herein, the notches may take any of numerous different shapes, configurations and/or sizes that may be desired to facilitate the manufacture and/or to enhance performance of the blades, or otherwise as desired. As described above, the notches  98  are preferably formed at step  118  of  FIG. 3B  in a progressive die or other suitable tool or equipment. 
   In the operation of the bending and snapping apparatus  142 , the composite strip  46  is fed through the blade gap  184  of the apparatus in the direction of the arrow C of  FIG. 10 , i.e., from the right-hand to the left-hand side in each of  FIGS. 8-10 . First, the composite strip  46  is secured in place by a locating pin (not shown) received within a respective registration aperture  26 . Then, the drive assembly  142  is driven toward the blade support  144 , and the first and second bending pins,  150  and  154 , respectively, and the first and second breaking punches  158  and  164 , respectively, are configured to successively bend and break the composite strip about each score line as hereinafter described. Initially, the first bending pin  150  is driven by the drive assembly  142  against the strip to bend the first triangle  188  of  FIG. 10  about the respective score line  64 , i.e., in the direction out of the page in  FIG. 10 . As can be seen, the portions of the composite strip  46  defining the respective score lines  64  are driven against the die  186  to thereby bend the respective triangle about the die and score line, and away from the blade support  144 . While the first bending pin  150  is bending the first triangle  188  outwardly, the first breaking punch  158  is pressed against the blade to simultaneously apply pressure to the composite strip  46  on the opposite side of the respective score line  64  relative to the first bending pin  150 . Next, the second bending pin  154  is driven against the composite strip  46  at the second triangle  190  of  FIG. 10  to, in turn, bend the second triangle outwardly around the respective score line, i.e., out of the page in  FIG. 10 . While the second bending pin  154  is bending the second triangle  190  outwardly, the second breaking punch  164  is pressed against the composite strip to simultaneously apply pressure to the composite strip on the opposite side of the respective score line  64  relative to the second bending pin  154 . The first breaking punch  158  then snaps the composite strip at the respective score line  64  and the first triangle  188  falls downwardly away from the blade. Then, the second breaking punch  164  snaps the composite strip at the respective score line  64 , and the spring-loaded pins  170  and  172  drive the resulting blade  10  outwardly into the blade magazine  148 . The drive assembly  142  is then driven rearwardly, i.e., away from the blade support  144 , the spring loaded presser plate  174  presses and, in turn, bends the second triangle  190  of the composite strip inwardly against the blade support  144  to thereby straighten the respective portion of the strip and allow its subsequent passage through the blade gap  184 , and the composite strip  46  is indexed forwardly through the blade gap to present the next blade section of the composite strip for bending and snapping in the manner described above. This process is repeated for each blade section until all blades  10  are bent and snapped away from the composite strip  46 . As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the bending pins and breaking punches may take any of numerous different shapes and/or configurations that are currently, or later become known for performing the functions of these components as described herein. For example, as shown in phantom in  FIG. 8 , the ends of the bending pins may be defined by angled surfaces to facilitate the bending operation. Similarly, the breaking punches may define angled or other surfaces to facilitate pressing and snapping the blades without damaging them. 
   As shown in  FIG. 8 , the blade magazine  148  includes an adjustable blade support  192  that is slidably mounted within the magazine, and the support  192  includes an adjustment knob  194  for fixedly securing the position of the blade support within the magazine. As the blades  10  are bent and snapped away from the composite strip  46 , they are stacked by the spring-loaded pins  170  and  172  against the blade support  192 . The drive assembly  142  further includes a blade guard  196  overlying the bending and snapping region of the apparatus  142  to prevent upward movement of the blades and retain them within the magazine. 
   Turning to  FIGS. 12A-12F , additional embodiments of a composite strip of the present invention are indicated generally by the reference number  246 . The composite strips  246  are similar to the composite strips  46  described above, and therefore like reference numerals preceded by the numeral “2” are used to indicate like elements where possible. One of the differences of the composite strips  246  in comparison to the composite strips  46  described above, is that the composite strips  246  are formed with elongated wear-resistant steel wires  244  that define predetermined cross-sectional shapes that substantially correspond to the final or ultimate shape of the second metal portion of the blade (e.g., the second metal portion  22  of the blade of  FIG. 1 ). For example, in  FIG. 12A , the high speed or tool steel wire  244  is substantially triangle-shaped in cross-section; in  FIG. 12D , the wire  244  is substantially trapezoidal-shaped in cross-section; in  FIG. 12E , the wire  244  is substantially triangle-shaped in cross-section, and is multi-faceted, defining a first pair of facets  230  and a second pair of facets  232 ; and in  FIG. 12F , the wire  244  also is substantially triangle-shaped in cross-section. 
   In each case, the cross-sectional shape of the wire  244  more closely corresponds to the cross-sectional shape of the second metal portion of the blades to be formed from the composite strip than does a square cross-sectional shaped wire, for example. Preferably, the cross-sectional shape of the wire  244  substantially matches the cross-sectional shape of the second metal portion of the blade. For example, if the cross-sectional shape of the second metal portion is triangular, than the cross-sectional shape of the elongated wire is preferably also triangular. However, manufacturing limitations and/or other considerations may require that the cross-sectional shape of the wire not match the cross-sectional shape of the second metal portion of the blade. For example, although the second metal portion of the blade may define a triangular cross-sectional shape, the pre-shaped wire may define a trapezoidal cross-sectional shape as shown, for example, in  FIG. 12D . The trapezoidal configuration may be tougher and otherwise may better prevent breakage of the high speed or tool steel portion during processing of the bi-metal strip, while nevertheless saving material and reducing processing time and expense in comparison to bi-metal blades without pre-shaped portions. 
   Accordingly, one advantage of pre-shaping the tool steel wire prior to forming the composite strip is that it reduces the amount of scrap generated during grinding and honing of the strip, and thus may enable a significant reduction in the amount of high speed or tool steel required to form the blades and, in turn, enable a decrease in the overall cost of the blades in comparison to blades formed from composite strips having, for example, round and/or square tool steel wires. For example, a conventional rectangular shaped high speed or tool steel wire, as described above, may define a width of about 0.04 inch and a height of about 0.025 inch. Thus, pre-shaping the wire in a triangular cross-sectional shape may reduce by about one half the amount of relatively expensive high speed or tool steel required to form the cutting edges of the blade in comparison to the same sized blades that employ rectangular wires. Although the trapezoidal shaped wires do not reduce by half the amount of high speed or tool steel in comparison to similarly sized rectangular wires, they nevertheless can significantly reduce the amount of high speed or tool steel required, and further, can reduce the amount of grinding required in comparison to blades that employ similarly sized rectangular wires. Accordingly, another advantage of employing pre-shaped wires is that they can significantly reduce the amount of grinding required and, in turn, increase the throughput of the manufacturing process, thus further enabling a decrease in overall cost of the blades. 
   As shown in  FIG. 12B , the backing steel is preferably provided in the form of one or more continuous elongated strips  234  wound into one or more coils. Each backing strip  234  defines an approximately planar upper side  236 , an approximately planar lower side  238 , and opposing back and front edges  240  and  242 , respectively. The high speed steel wire  244 , on the other hand, may take the shape of any of numerous different pre-shaped forms as indicated, for example, in  FIGS. 12A-12F , and is preferably provided in the form of one or more continuous lengths of wire  244  wound into one or more coils. 
   The wire  244  may be provided in round form. In this case, it may be necessary to draw the round stock through a drawing die or series of drawing dies in a manner known to those of ordinary skill in the pertinent art in order to reduce the diameter to that necessary or otherwise desired for further processing. Then, the drawn round wire is shaped into the desired predetermined shape that substantially corresponds to the shape of the second metal portion of the blade, as shown, for example, in  FIGS. 12A-12F , by any of numerous different wire shaping processes that are currently or later become known for performing this process. For example, the wire may be formed into the predetermined shape by one or more of: (a) rolling the wire; (b) passing the wire through a Turks Head; and (c) passing the wire through a draw die. Depending upon the width-to-thickness ratio of the desired predetermined wire shape, it may be desirable to employ a combination of these processes. For example, a Turks Head operation may be used to create a square wire, whereas a combination of rolling and Turks Head operations may be used to create rectangular, trapezoidal or triangular pre-shaped wires. Exemplary wire shaping apparatus include Turks Head and wire shaping mills, such as the combination Turks Head/Rolling Mills, or other wire flattening and shaping mills, such as those manufactured by Fenn Manufacturing of Newington, Conn. U.S.A., or other profiling rolling machines, such as those manufactured by Karl Fuhr GmbH &amp; Co. KG of Germany. The Turks Head is believed to facilitate the formation of relatively sharp corners that, in turn, allow the wire to intimately contact the corresponding surface of the backing strip throughout the interface between the two components to thereby ensure the integrity of the weld. 
   As shown in  FIG. 12B , the high speed or tool steel wire  244  is butt joined to the front edge  242  of the backing strip  234 , and thermal energy is applied to the interface between the wire and the backing strip to, in turn, weld the wire to the backing strip and form a bimetal or composite strip  246  defining the first metal portion  220  formed by the steel backing strip  234 , the second metal portion  222  formed by the high speed steel wire  244 , and the weld region  228  joining the first and second metal portions. As shown in  FIG. 12B , a typical welding apparatus includes opposing rollers  250  laterally spaced relative to each other for butt joining the high speed steel wire  244  to the front edge  242  of the backing strip  234 , and rotatably driving the composite or bi-metal strip  246  through the welding apparatus. A thermal energy source  252  is mounted within the welding apparatus and applies thermal energy to the interface of the high speed steel wire  244  and front edge  242  of the backing strip to weld the wire to the backing strip. 
   The composite strip  246  is then processed in the same manner as any of the composite strips described above in order to form therefrom the composite utility blades. As indicated above, a significant advantage of the composite strip  246  is that it may use less high speed steel and/or increase the manufacturing throughput than otherwise might be achieved without pre-shaping the wire. 
   Turning to  FIGS. 11A-11D , the blade  10  may take any of numerous different shapes and/or configurations. As shown in  FIG. 11A , the cutting edge  14  of the trapezoidal blade  10  may define squared corners formed by the notches  98  described above with reference to  FIG. 10 . In  FIG. 11B , the cutting edge  14  of the blade may define rounded corners by forming correspondingly shaped notches  98  in the composite strip  46 . Alternatively, as shown in dashed lines in  FIG. 11B , the blade  10  may define a rectangular shape, or as shown in the dashed-dotted lines, the blade may define a parallelogram. In  FIG. 11C , the blade  10  defines a plurality of parallelogram-shaped segments separated by score lines  64  and respective notches  98 . The notches  98  extend laterally into each second metal portion in the same manner as the notches  98  described above with reference to  FIG. 10 . The blade  10  of  FIG. 11C  is designed for use in a “snap-off” blade holder of a type known to those of ordinary skill in the pertinent art whereby each parallelogram-shaped segment (or other shaped segment, if desired) may be snapped off when the respective cutting edge segment  14  becomes worn to, in turn, expose a fresh cutting edge segment. Similarly, although the composite utility blades  10  described above define a bi-metal construction, the blades of the present invention may equally define a tri-metal or other composite construction. For example, as shown in  FIG. 11D , the utility blades of the present invention may define high speed or tool steel cutting edges  14 ,  14 ′ (the second cutting edge  14 ′ being shown in broken lines) formed on opposite sides of the blade relative to each other, with a relatively tough, spring-like portion formed between the outer high speed steel edges. Similarly, a tri-metal strip may be cut down the middle, or otherwise cut along an axially-extending line to form two bi-metal strips which each may, in turn, be cut to form the blades of the present invention. As also shown in  FIG. 11D , the corners of the cutting edges  14 ,  14 ′ may be formed by lateral surfaces oriented at oblique angles relative to the cutting edge. 
   In addition, many, if not all, of the coiling and uncoiling steps shown in  FIGS. 3A and 3B  may be eliminated by employing in-line processing apparatus. Also, the blades first may be blanked from the composite strip, such as by die-cutting or bending and snapping, and then the heat treating, grinding and other finishing steps may be performed on the blanked blades to form the final utility blades. 
   In some embodiments, a blade in accordance with any of the embodiments described hereinabove, is provided with one or more coatings. Such coating(s) may be provided for one or more of a number of reasons. For example, some types of coatings are purely decorative (i.e., non-functional or cosmetic). Some other types of coatings are purely functional (e.g., wear and/or corrosion resistance). Some other types of coatings may have decorative and functional aspects. Moreover, one or more coating(s) may be provided on top of one or more other coating(s). For example, in some embodiments, a functional coating is provided over a blade (or portion(s) thereof) and a decorative coating is provided over the functional coating (or portion(s) thereof). A coating may be provided over an entire blade or any portion thereof (e.g., the cutting edge  14  or portion(s) thereof). 
   As used herein, except where otherwise stated, the phrases “decorative” coating and “cosmetic” coating, mean at least primarily “decorative” and at least primarily “cosmetic”, respectively, so as not to preclude the possibility that a decorative coating or a cosmetic coating, respectively, provide some amount of wear and/or corrosion resistance (or some other non-decorative or non cosmetic property). For example, decorative coatings may provide some measure of wear and/or corrosion resistance. However, the amount of wear and/or corrosion resistance (or other property) provided by a decorative or cosmetic coating will generally be small compared to that of a purely functional coating of similar thickness and suitable composition. 
   Some examples of different types of coatings include carbide coatings, nitride coatings, and combinations thereof. Coatings intended to reduce the rate of wear of the blade may comprise, for example, any suitable material(s) including but not limited to titanium nitride (TiN), chrome nitride (CrN), titanium carbide (TiC), ceramic(s), titanium carbonitride (TiCN), Aluminum Titanium Nitride (AlTiN), Aluminum Titanium Carbonitride (AlTiCN), Zirconium Nitride (ZrN), Zirconium Carbonitride (ZrCN), and/or combinations thereof. 
   Some types of decorative coatings are used to make a blade (or portion(s) thereof, e.g., the cutting edge  14 , or portion(s) thereof) having a colored appearance, e.g., gold, or any of numerous other colors. Some of such decorative coatings are comprised of titanium nitride (TiN). In some embodiments, a decorative coating is applied only to one or more of the first facets  30  (or portion(s) thereof), thereby defining colored strip(s) over the cutting edge  14 . 
   Some methods for use in providing functional (e.g., wear or abrasion resistant coatings) on a blade include the step of heating the base material (e.g., carbon steel). Although such heating may cause a reduction in the hardness of the base material it also increases the ability of the base material to support the coating, which helps the coating hold up better against heat generated during cutting operations. For a base material formed of carbon steel, the temperature may be, but is not limited to, a temperature in the range of about 300° F. to about 400° F. For high speed steel, the temperature may be, but is not limited to, a temperature of about 1000° F. In some embodiments, the temperature may be greater than about 1000° F. One advantage of the bi-metal blades of the currently preferred embodiments of the present invention is that the high speed steels used to form the cutting edges can be heated to temperatures on the order at least about 1000° F. without damage thereto, and therefore such blades are uniquely suited for coatings that require high temperatures or that permit operation under high temperatures, such as AlTiN or other PVD coatings. Accordingly, if relatively high temperatures are generated at the cutting edges of the AlTiN coated blades of the present invention, the coating can better withstand the heat in comparison to prior art blades. If some conventional carbon steels, on the other hand, are heated to temperatures above between about 300° F. and about 400° F., the steel can lose its hardness and strength and, in turn, lose its ability to properly support some such coatings. 
   In at least some embodiments, one or more coating(s) are provided using physical vapor deposition (PVD). Physical vapor deposition may be carried out in any suitable manner including but not limited to using cathodic arc deposition, thermal/electron beam deposition, and/or sputter deposition. However coatings also may be provided by other methods. Indeed, coatings may be provided using any suitable manner including but not limited to painting, spraying, brushing, dipping, plating (electroplating or electro-less plating), physical and/or chemical vapor deposition, or any combination thereof. Powder coatings and e-coatings, and/or combinations of any of the above, also may be employed. 
   In accordance with currently preferred embodiments of the present invention, the utility blades are coated with either TiN or AlTiN, or with an inner layer of AlTiN and an outer layer of TiN for a gold-colored appearance. The coatings extend along the cutting edge, and along the sides of the blade adjacent to the cutting edge. The AlTiN coatings are applied to the pre-sharpened blades in a thickness within the range of about 3 micrometers to about 5 micrometers. In the embodiment employing an inner coating of AlTiN and out outer coating of TiN, the outer coater is thinner than the inner coating. Also in a currently preferred embodiment of the present invention, the AlTiN coating is applied so as to provide a gradient (linear or otherwise) such that the concentration of aluminum increases from about 32% (atomic percent) at the substrate surface to about 66% at the outer surface of the coating. One advantage of this configuration is that the higher concentration of titanium at the substrate/coating interface facilitates adhesion of the coating to the substrate. 
   The AlTiN and TiN coatings are applied to the blades in a commercially available cathodic arc deposition system, in which the coiled bi-metal strips (or separated blades if so desired) are processed through a multistage cleaning system to remove the bulk of surface contaminant soils. The PVD coating chamber is of a conventional type including gas lines for oxygen, nitrogen, argon, and methane/acetylene; a vacuum pump system coupled in fluid communication with the chamber for evacuating the chamber; a plurality of targets spaced relative to each other about the chamber; a water circulating unit that circulates hot and cold water via a closed loop system to the chamber; and a plurality of evaporators and evaporator power supplies. 
   Each bi-metal strip is preferably wound into a coil with a buffer strip interposed between the windings of the bi-metal strip. The buffer strip may be formed, for example, of stainless steel, and may define a plurality of axially spaced dimples projecting laterally therefrom to define a pre-determined spacing between adjacent windings of the bi-metal coil. The width of the buffer strip is preferably less than the width of the bi-metal strip. Thus, when the strips are wound together into a coil, the back edges of the strips are preferably aligned such that the cutting edge of the bi-metal strip extends beyond the corresponding edge of the buffer strip. The exposed portions of the bi-metal strip will be exposed to the targets, and thus will be coated with the AlTiN, TiN, AlTiN/TiN, or other PVD coating. Thus, the extent to which the bi-metal strip extends beyond the corresponding edge of the buffer strip defines the depth of coating on the bi-metal strip (or the width of the coating on opposing sides of the cutting edge). 
   A plurality of such coils are mounted on cross-shaped or other suitable fixtures for holding the coils in the coating chamber and allowing relative movement between the coils and targets for coating the cutting edges of the bi-metal strips. The exposed edges or cutting edges of the bi-metal coiled strips are preferably oriented in planes approximately parallel to the planes of the targets (i.e., the cutting edges are mounted to face the targets and to receive a substantially uniform PVD coating therefrom). The cross-shaped or other suitable fixtures for holding the coils are mounted on a planetary fixture that is received within the coating chamber and rotatably driven therein. The cross-shaped fixtures and coils mounted thereon are mounted on the planetary fixture such that they are axially and angularly spaced relative to each other. In one embodiment, the planetary fixture can hold about 8 coils, with a first set of four coils angularly spaced about 90° relative to each other, and a second set of four coils angularly spaced about 90° relative to each other and axially spaced relative to the first set of four coils. If desired, the two sets of coils can be angularly offset about 90° or otherwise relative to each other. 
   Once the coils are mounted within the coating chamber, the chamber is pumped down to insure a pure processing environment consisting of only the cleaned bi-metal strips to be coated and the solid material to be vaporized. Then, after the extremely low pressure or high vacuum pure environment is created, the coiled bi-metal strips are gently heated. Heating ensures out gassing of the bi-metal substrates and raises the core and surface temperatures of the bi-metal substrates to better match the thermodynamics of the coating cycle. One embodiment of the system uses PID controlled heaters to coat at a temperature within the range of about 100°-120° F. for a time period within the range of about 0-150 minutes. 
   The apparatus then performs etching by employing a combination of sputter etches at a high bias voltage and arc assisted argon etches at a high bias voltage (the apparatus may transition from sputter etch to arc assisted glow discharge etch in steps). Etch depth is controlled in a manner known to those of ordinary skill in the pertinent art. The sputter etch is a Ti ion bombard etch where the surface is heated up and conditioned by ramping the voltage in discrete steps as a precursor to an arc enhanced glow discharge. The arc enhanced glow discharge uses a Mod pulsar system for substrate conditioning. The shutter closes on the Ti/Cr targets and there is a generation of a glow (plasma) using bias voltage that gradually raises from 0 to about 400 V in steps with two targets running from 0 to about 85 V. 
   The next phase consists of Argon gas plasma cleaning (etching) of the substrates inside the vacuum chamber. The Argon back sputter ion cleaning is effective in atomically preparing the surface of the substrates by removing oxide layers and exposing native surfaces. One advantage of this feature is that it facilitates adhering the coating to the substrate and not to any oxides or other contaminants that otherwise could be located on the surface of the substrate. 
   The reactive coating process is performed at about 0-500 V bias and by turning on the evaporators from about 0-85 amps on the targets. Process gases are bled into the chamber and the coating material is vaporized and condensed or deposited on the exposed cutting edges and adjacent surfaces of the wound bi-metal substrates. The desired coating thickness is reached by allowing the vaporization to continue for a predetermined amount of time. Coating times may vary from about 30 minutes to about four hours. As described above, in currently preferred embodiments of the present invention, the coatings consist of either TiN or AlTiN, or an inner coating of AlTiN with an outer coating of TiN to achieve a gold-colored appearance. In a currently preferred embodiment of the present invention, the AlTiN coating is applied in a thickness within the range of about 3 micrometers to about 5 micrometers. In the embodiment including an inner AlTiN coating, and an outer TiN coating, the outer TiN coating is thinner than the inner AlTiN coating. The coating(s) preferably are applied in stripes or like narrow bands extending along opposite sides of the cutting edge relative to each other. In the currently preferred embodiments of the present invention, the width of each stripe is preferably within the range of about 0.005 inch through about 0.025 inch (for blades having a width of about 0.75 inch and a thickness of about 0.025 each). In one currently preferred embodiment of the present invention, the width of the stripe is about 0.125 inch. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the coatings may cover all and/or other portions of the blades, as may be applied in a format other than a stripe. Once the coating process is completed, the wound bi-metal strips are allowed to cool, the chamber is brought back to atmospheric pressure, and the coated bi-metal strips are removed and are ready for separating same into the individual blades as described above. Exemplary procedural steps involved in coating utility blades as described above are illustrated in Table 1 below. 
   
     
       
         
             
           
             
               TABLE 1 
             
             
                 
             
           
          
             
               
                 
                   
                   
                       
                       
                   
                 
               
             
             
                 
             
          
         
       
     
   
   Some types of coatings and methods for providing such coatings are described by Teer, D. G., et al., “Self Lubricating Coatings for the Protection of Cutting and Forming Tools and Mechanical Components”, Vacuum Technology &amp; Coating, Society of Vacuum Coaters, October 2000, pp. 48-53, which is incorporated by reference herein. However, other types of coating(s) and method(s), or combinations thereof, also may be used. 
   Of course, as indicated above, the utility blades and processes of making such blades in accordance with the present invention do not require coating(s). 
   Accordingly, as may be recognized by those skilled in the pertinent art based on the teachings herein, numerous changes and modifications may be made to the above-described and other embodiments of the composite utility blades and the methods of making such blades of the present invention without departing from the scope of the invention as defined in the appended claims. This detailed description of preferred embodiments is to be taken in an illustrative, as opposed to a limiting sense.