Abstract:
A chisel blade with a permanently attached shaft is disclosed. The chisel blade and shaft are dimensioned and configured such that shaft is removably attachable to a portable heating element. The chisel blade with an attached shaft may include a portable soldering iron with the soldering tip removed. In the two possible embodiments, the chisel blade has a rectangular shape with a beveled cutting surface having a straight cutting edge. In a third embodiment, the chisel blade is concave and the beveled cutting edge is concave.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the U.S. Provisional Patent Application No. 61/210374 filed Mar. 18, 2009 by the present inventors. This provisional patent application is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to cutting instruments. More particularly the invention relates to cutting instruments in which the cutting blade is heated. 
       BACKGROUND 
       [0003]    There are many inventions directed to removable blades that are attached to a hand-held handle. There are also inventions in which a blade is attached to a hand-held heating element to serve a specific function such as cutting honeycombs or shaping dental molds. There are also inventions in which a hand-held heating element is used with a removable blade. These are called tire groovers and they are used to cut grooves in the rubber without applying excessive heat that would damage the rubber. However, some of these inventions are customized, expensive tools. Others have blades that are thin and fragile. Thus, there is a need for an inexpensive tool that is used to trim the knobs of a tire on a dirt bike or similar tire after the tire is used in a race such that the knob&#39;s edges are restored to their original sharpness. Furthermore, the tool should have a durable blade that is easy to use, keeps its sharpness for extended periods, and is easily resharpened. 
       SUMMARY 
       [0004]    The present invention provides a low cost, easily manufactured device that allows the user to trim the knobs of off road tires easily and effectively. The invention is a chisel blade with an attached chisel shaft that replaces the soldering tip commonly used in soldering irons. The invention is useful for trimming the knobs of dirt bike tires without damaging them. The invention is used to trim motorcycle and dirt bike tires to recondition them in the field after being used in off-road motorcycle and dirt bike competitions and recreational use. The invention provides the correct amount of heat for trimming the tire knobs easily and without damaging the remaining rubber on the tire. Furthermore, the blade retains its sharpness and strength for a long time. 
         [0005]    The present invention has a simple but effective design that is inexpensively manufactured and may be deployed simply by replacing the soldering tip of a soldering iron or similar heating device with the removable chisel blade. The invention provides a useful tool for trimming knobby tire treads and other tire treads used in competition and recreational activities. Furthermore, unlike other products that are designed to cut tire treads, the removable chisel blade is essentially unbreakable, retains its sharpness for extended periods of time, and is resharpened easily with tool sharpeners commonly available to the consumer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates a front perspective view of a first embodiment of the removable chisel blade. 
           [0007]      FIG. 2  illustrates a front view of the removable chisel blade of  FIG. 1 . 
           [0008]      FIG. 3  illustrates a left side view of the removable chisel blade of  FIG. 1 . 
           [0009]      FIG. 4  illustrates an exploded view of the removable chisel blade of  FIG. 1 . 
           [0010]      FIG. 5  illustrates a prior art soldering iron with a soldering tip. 
           [0011]      FIG. 6  illustrates the removable chisel blade attached to a soldering iron. 
           [0012]      FIG. 6A  illustrates a close up view of  FIG. 6  illustrating the chisel blade attached to the soldering iron. 
           [0013]      FIG. 7  illustrates a front perspective view of a second embodiment of the removable chisel blade. 
           [0014]      FIG. 8  illustrates a front view of the second embodiment of the removable chisel blade. 
           [0015]      FIG. 9  illustrates a left side view of the second embodiment of the removable chisel blade. 
           [0016]      FIG. 10  illustrates an exploded view of the second embodiment of the removable chisel blade. 
           [0017]      FIG. 11  illustrates a front perspective view of a third embodiment of the removable chisel blade. 
           [0018]      FIG. 12  illustrates a front view of the third embodiment of the removable chisel blade. 
           [0019]      FIG. 13  illustrates a left side view of the third embodiment of the removable chisel blade. 
           [0020]      FIG. 14  illustrates an exploded view of the third embodiment of the removable chisel blade. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    As used in this specification and claims, the phrase soldering iron refers to a hand held soldering iron that has a removable soldering iron tip. The term removable chisel blade refers to a chisel blade with a shaft attached. 
         [0022]    In the following description, the terms top, bottom, front, back, left and right refer to the figure where each reference is first introduced. The term concave upward refers to a curved shape that in the figure it refers to “holds water”. Similarly, concave to the right is a curved shape that when rotated counterclockwise approximately 90 degrees becomes concave upwards. 
         [0023]      FIGS. 1 through 4  illustrate a first embodiment of the invention. Referring to  FIG. 1 , the removable chisel blade  100  of the first embodiment is comprised of a chisel blade  102  and a chisel shaft  104 . The chisel blade  102  has the shape of a flat rectangular solid that has been beveled so it has a flat surface  106  with a cutting edge  112 . The cutting edge  112  is disposed at the top back of the chisel blade  102 . The chisel shaft  104  is a cylindrical solid. As seen in  FIGS. 2 and 3  the chisel blade  102  is joined to the chisel shaft  104  with a weld  110 . 
         [0024]    Referring to  FIGS. 1 through 4 , the top  120  of the chisel shaft  104  has a circular shape and is attached at the bottom  108  of the chisel blade  102  equidistant from the left side  114  and the right side  116  of the chisel blade  102 . The axial direction A of the chisel shaft  104  is parallel to the left  114  and the right  116  sides of the chisel blade  102 . The back  126  of the chisel shaft  104  is aligned with the back  124  of the chisel blade  102  as shown in  FIG. 3 . If the diameter d of the chisel shaft  104  is larger than the thickness t of the chisel blade  102 , then the chisel shaft top  120  may have a protruding ridge  128  at the front  122  of the chisel blade  102 . 
         [0025]      FIG. 5  illustrates a prior art soldering iron  202 . The prior art soldering iron has a removable soldering tip  206 . The soldering iron  202  has a tubular shaft  204 , a handle  208  and an electrical cord  212 . The soldering iron tip  206  is secured to the shaft  204  with adjusting screws  210 . 
         [0026]      FIG. 6  illustrates the disposition of the removable chisel blade  100  in the soldering iron shaft  204 .  FIG. 6A  illustrates a detail of the soldering iron with the removable chisel blade  100  installed. To install the removable chisel blade  100  on the soldering iron  202 , the soldering iron tip is removed. Then the adjusting screws  210  of the soldering iron shaft  204  are loosened sufficiently such that the chisel shaft  104  of the removable chisel blade is inserted in the interior cylinder  302  of the soldering iron shaft  204 . The adjusting screws  210  are then tightened securing the chisel shaft  104 . 
         [0027]      FIGS. 7 through 10  illustrate a second embodiment of the invention. Instead of the flat chisel shaft  104  of the first embodiment, a chisel shaft  404  with an L-shaped notched top  406  is provided as shown in  FIGS. 7 ,  9  and  10  replaces the flat top  120  of the first embodiment. The notch  406  provides extra surface area for the weld  410  and presents a more pleasant appearance. The chisel shaft  404  has threads  408  disposed on the bottom portion of the chisel shaft  404 . The threads  408  are configured to be used with a soldering iron that accepts threaded shafts. The threads  408  ensure excellent contact between the chisel shaft  404  and a soldering iron designed to accept a threaded tip. 
         [0028]      FIGS. 11 through 14  illustrate a third embodiment of the invention. Instead of the beveled chisel blade  102  of the first embodiment, the blade body is concave and has a concave cutting edge. Referring to  FIG. 12 , the cutting edge  512  is upwardly concave. The back of the blade  524  is concave to the right as illustrated in  FIG. 13 . 
         [0029]    Any dimensions, configurations or materials of the chisel blade and chisel shaft that are compatible with existing or newly designed soldering irons and function in a manner equivalent to the three embodiments presented herein are within the scope of this inventive concept. 
         [0030]    The invention comprises the removable chisel blade or optionally the removable chisel blade with a soldering iron. As one example of a typical implementation, the chisel blade  102  is made from tool steel with the beveled flat surface ground to form a sharp cutting edge  112 . The size of the chisel blade  102  comes in several sizes with widths from 20 mm (¾ inch) to 51 mm (2 in), a height of 20 mm (¾ inch) and a thickness of 4.0 mm ( 5/32 in). The chisel shaft  104  is made from a welding rod with a diameter selected to fit the sleeve of a soldering iron. Typical diameters are ¼ inch and ⅜ inch. Alternatively, the shaft may have threads to fit in a soldering iron that accepts soldering iron tips with threads. 
         [0031]    Various modifications to the embodiments are within the inventive concept presented here. The electric soldering iron may be replaced by a portable propane-powered soldering iron or a soldering iron powered by a car battery or rechargeable portable battery. A shaft that has a different cross section, such as a hexagon, may replace the cylindrical solid shaft. Additionally, the shaft may have a bend in it. The chisel blade and chisel shaft may be made from single piece of material. The chisel shaft may be joined to the chisel blade by means other than welding, such as screws. The chisel blade may be permanently attached to the heating element so that it is not removable. 
         [0032]    The disclosure presented herein presents three embodiments of the invention. These embodiments are to be considered as only illustrative of the invention and not a limitation of the scope of the invention. Various permutations, combinations, variations and extensions of these embodiments are considered to fall within the scope of this invention.