Patent Grant
9126259
The present invention relates to utility knife blades, and more particularly, to composite utility knife 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 knife blades.
Conventional utility knife 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.
Conventional utility knife 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 shaped utility knife 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 knife blades is that each blade is formed of a single material, typically carbon steel, that 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 knife 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 convention utility knife 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 knife 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 knife blade field.
In stark contrast to the utility knife 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 knife blades defining a bi-metal or other composite construction as with bi-metal band saw blades. In addition, there are numerous obstacles preventing the application of such band saw blade technology to the manufacture of utility knife blades. For example, as described above, conventional utility knife 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-shaped blades. However, the relatively tough, spring-like backing used, for example, to manufacture bi-metal band saw blades, cannot be scored and snapped. Rather, such relatively tough materials require different processes to form the utility knife blades from a heat treated, composite strip. In addition, the heat treating applied to conventional utility knife blades could not be used to heat treat bi-metal or other composite utility knife blades.
Accordingly, it is an object of the present disclosure to overcome one or more of the above-described drawbacks and disadvantages of prior art utility knife blades and methods of making such blades, and to provide a bi-metal or other composite utility knife blade defining a relatively hard, wear-resistant cutting edge, and a relatively tough, spring-like backing, and a method of making such utility knife blades.
The present disclosure is directed to a composite utility knife 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. Preferably, the back, cutting and side edges of the blade define an approximately trapezoidal peripheral configuration. The composite utility knife blade 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 hardness 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 hardness 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.
The present invention is also directed to a method of making composite utility knife blades. 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 of the annealed composite strip. The annealed and punched composite strip is then hardened such that the first metal portion defines a surface hardness within the range of approximately 38 Rc to approximately 52 Rc, and the second metal portion defines a surface hardness 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 along shear lines axially spaced relative to each other. Each shear line is oriented at an acute angle relative to the back edge of the first metal portion, and at least one notch is located between adjacent shear lines. The die cutting of the composite strip forms a plurality of utility knife blades, wherein each utility knife blade defines an approximately trapezoidal peripheral configuration and at least one notch is formed in the back edge thereof.
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, such as by punching, at the interface of each shear line and the second metal portion, to thereby separate the high speed steel cutting edges of adjacent composite utility knife blades formed from the composite strip. Then, during the die-cutting step, only the first metal portion of the hardened composite strip is die cut along the axially spaced shear lines to thereby form the plurality of utility knife blades from the composite strip.
One advantage of the utility knife blades and method 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 knife blades as described above. Thus, the utility knife blades and method of the present invention provide significantly improved blade life, and cutting performance throughout the blade life, in comparison to conventional utility knife blades. In addition, the utility knife blades, and method of making such blades, is relatively cost effective, particularly in comparison to the composite utility knife blades defining sandwiched, laminated and/or coated constructions, as also described above. As a result, the utility knife blades and method of the present invention provide a combination of wear resistance, toughness, cutting performance, and cost effectiveness heretofore believed to be commercially unavailable in utility knife 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.
In
The blade 10 further defines a first metal portion 20 and a second metal portion 22. As shown typically in
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 knife blades made in accordance with the method of the present invention define highly wear-resistant, long-lasting cutting edges, combined with virtually unbreakable or shatter-proof backings. Thus, in stark contrast to the typical utility knife blades of the prior art, the composite utility knife blades made in accordance with the method 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 standard AISI grades, including 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, 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., and T Series grades, such as T1, T4, T8, etc.
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 knife blades in accordance with the present invention.
As further shown in
As also shown in
As further shown in
As also shown in
Turning to
At step 104 of
As shown at step 106 of
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 bi-metal 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 bi-metal 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 bi-metal strip 46 may be coiled again, if necessary, for transportation and further processing. As shown at step 116 of
As shown at step 120 of
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 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 and punching 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 bend and snap 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
As shown in
In accordance with an alternative embodiment of the present invention, and as shown typically in
The notches 98 of
Turning against to
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 knife 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. For example, although the composite utility knife blades 10 illustrated herein define a bi-metal construction, the blades made in accordance with the present invention may equally define a tri-metal or other composite construction. For example, the utility knife blades made in accordance with the present invention may equally define high speed or tool steel cutting edges formed on opposite sides of the blade relative to each other, with a relatively tough, spring-like portion formed between the outer high speed or tool 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 in accordance with the present invention. In addition, many, if not all, of the coiling and uncoiling steps shown in
This patent application is a continuation of U.S. patent application Ser. No. 10/792,415, filed Mar. 3, 2004, entitled “Method of Making a Composite Utility Blade,” now U.S. Pat. No. 7,658,129, which is a divisional of U.S. patent application Ser. No. 09/916,018, filed Jul. 26, 2001, entitled “Composite Utility Knife Blade, and Method of Making Such a Blade,” now U.S. Pat. No. 6,701,627, which are hereby expressly incorporated by reference as part of the present disclosure. This application is related to U.S. patent application Ser. No. 10/202,703, filed Jul. 24, 2002, entitled “Composite Utility Knife Blade, and Method of Making Such a Blade,” now U.S. Pat. No. 8,291,602, which is a continuation-in-part of U.S. patent application Ser. No. 09/916,018, now U.S. Pat. No. 6,701,627.
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| Number | Date | Country | |
|---|---|---|---|
| 20100263491 A1 | Oct 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09916018 | Jul 2001 | US |
| Child | 10792415 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10792415 | Mar 2004 | US |
| Child | 12702151 | US |
