Abstract:
An utility knife and method of blade removal in a utility knife comprising releasing a cam pressure using a lever on a fastener holding a first half and a second half of a handle of a utility knife; separating the first half and second half; and rotating the first half from the alignment with the second half to allow a blade to be removed are shown.

Description:
[0001]    The present invention relates to the field of cutting tools. Particularly, it relates to cutting tools such as utility knifes with replaceable blades. In one preferred embodiment, it relates to a utility knife with a fixed, clamped blade of the style often used by drywall hanging professionals. 
       BACKGROUND 
       [0002]    Cutting tools with replaceable blades are well known and are generally referred to as utility knives. Generally, utility knife designs require a closing mechanism of some sort to hold the halves of the knife together. This closing mechanism is typically a threaded screw, requiring a screwdriver or similar tool simply to replace the blade. 
         [0003]    There is a need to improve the mechanical properties of the utility knife such that the closing mechanism does not need an additional tool, is easy to use and has a quick release. 
         [0004]    Information relevant to utility knives can be found in U.S. Pat. Nos. 3,509,627 (Gilbert et al.), 3,660,895 (West), 4,068,375 (Rathbun et al.), 4,524,518 (West), 4,604,805 (Krieger), 4,939,839 (Gorst), 5,005,290 (Gilbert), 5,022,156 (Kallens et al.), 5,301,428 (Wilcox), 5,404,645 (Janser), 5,862,596 (Chung), 5,864,952 (Chung), 5,878,501 (Owens et al.), 6,026,575 (Haung), 6,223,439 (Wonderley) and 6,971,178 (Rowlay). Each of the foregoing United States patent is incorporated herein by reference. Each one of these referenced items, however, suffers from one or more of the needs cited above. 
         [0005]    For example, one disadvantage is that the closing mechanism having a screw thread requires an additional tool. 
         [0006]    For example, another disadvantage is that the threaded screw may be lost if removed. 
       SUMMARY 
       [0007]    It is an object of the present invention in one embodiment to allow blades to be replaced with the movement of a lever. The lever has a cam lobe and pivot at its end, allowing force to be applied to the two halves of the knife and the blade without the need for a threaded closing mechanism. 
         [0008]    It is a further object of the present invention in one embodiment to provide a utility knife for mounting a blade comprising a lever having a cam with an eccentric rotation axis; a handle for the utility knife comprising: a first half having a recessed pocket and a first slot, a second half having a forward inner section wherein a blade is mounted to extend at least partially past the forward inner section; and a fastener comprising a first end and a second end; wherein the fastener is coupled to the second half and the first end of the fastener passes through the first slot and rotatably couples to the cam of the lever; and wherein the first half and the second half couple and uncouple by the force of the cam movement. Preferably, in this embodiment, the first half further comprises a first interlocking lobe and a first lobe coupler at a forward section and the second half further comprises a second interlocking lobe and a second lobe coupler at a forward section wherein the first interlocking lobe and second lobe coupler matingly couple and the second interlocking lobe and the first lobe coupler matingly couple. Also, preferrably, the second half further comprises at least one rear interlocking alignment rib wherein the at least one interlocking alignment rib couples to the first half for alignment thereof, and more preferably yet, the at least one rear interlocking alignment rib comprises four interlocking alignment ribs. 
         [0009]    In yet another preferred embodiment, the second half further comprises a blade support made of magnetic material. Likewise in a preferred embodiment, the second half may further comprise a second slot wherein the fastener passes before passing through the first slot, and more preferably the second end of the fastener further comprises a rectangular portion. 
         [0010]    Most preferably, the invention may further comprise a spring placed between the second half and first half through which the fastener passes, comprising a friction plate having a friction slot and an alignment tooth and wherein the first half further comprises a first recessed portion adapted to receive the friction plate, and the second recessed portion further comprises spacing ribs. 
         [0011]    Another preferred embodiment of the invention provides a method of blade removal in a utility knife comprising: releasing a cam pressure using a lever on a fastener holding together a first half and a second half of a handle of a utility knife; separating the first half and second half; and rotating the first half from the alignment with the second half to allow a blade to be removed. 
         [0012]    Another preferred embodiment of the invention may comprise a utility knife for mounting a blade including a lever having a cam with an eccentric rotation axis; a handle for the utility knife comprising: a first half having a recessed pocket and a first slot, a second half having a forward inner section wherein the blade is mounted to extend at least partially past the forward inner section, and a fastener comprising a first end and a second end wherein the fastener is connected to the second half and coupled to the first end of the fastener that passes through the first slot and rotatably couples to the cam of the lever; and wherein the first half and the second half couple and uncouple by the force of the cam movement 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective top view of one preferred embodiment of a utility knife including a blade. 
           [0014]      FIG. 2  is a perspective bottom view of one preferred embodiment of a utility knife including a blade. 
           [0015]      FIG. 3   a  is a perspective top view of one preferred embodiment of a utility knife including a blade with a lever in an up open position. 
           [0016]      FIG. 3   b  is a perspective top view of one preferred embodiment of a utility knife including a blade with a lever in an up and reversed open position. 
           [0017]      FIG. 4  is a perspective top view of one preferred embodiment of a utility knife in an open position. 
           [0018]      FIG. 5  is an exploded side top view of one preferred embodiment of a utility knife. 
           [0019]      FIG. 6  is an exploded side bottom view of one preferred embodiment of a utility knife. 
           [0020]      FIG. 7  is a side view of one preferred embodiment of a lever side of a utility knife showing a line A-A. 
           [0021]      FIG. 8  is a cross-sectional view of one preferred embodiment of a lever side of a utility knife taken along the line A-A in  FIG. 7 . 
           [0022]      FIG. 9  is a side view of one preferred embodiment of a lever side of a utility knife in a closed position showing a line B-B. 
           [0023]      FIG. 10  is a cross-sectional view of one preferred embodiment of a lever side of a utility knife taken along the line B-B in  FIG. 9 . 
           [0024]      FIG. 11  is a side perspective view of one preferred embodiment of a non-lever side showing a specific section C. 
           [0025]      FIG. 12  is an enlarged view of one preferred embodiment of a non-lever side showing the section C in detail. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, attention is first directed to  FIGS. 1 and 2  which show a perspective top and bottom view of a utility knife  10  incorporating one preferred embodiment of the invention generally comprising a substantially hollow handle  20  having a forward section  22  and rear section  28  comprising a first half  30  and a second half  40  which receive the blade  50 . The exterior of the handle  20  is suitably shaped to facilitate manual holding of handle  20  and use of the utility knife  10  to perform various cutting tasks using the blade  50 . The first half  30  and the second half  40  have opposed interlocking lobes, a first interlocking lobe  60  and a second interlocking lobe  70 , respectively, that, in this preferred embodiment, are located on the forward section  22  of the handle  20 . First interlocking lobe  60  and second interlocking lobe  70  matingly couple respectively with a second lobe coupler  90  and a first lobe coupler  80  when the first half  30  and second half  40  are coupled in a closed position. In this preferred embodiment, the first half  30  comprises a recessed pocket  100  in which the lever  110  including a cam  120  having an eccentric rotation axis  130  at one end  135  that is adapted to matingly couple about to a fastener  140  having a first end  150  and a second end  160 , as shown in  FIG. 5 , wherein the second end  160  is coupled to the second half  40  and the first end  150  is coupled to the cam  120  such that the lifting of the lever  110  from the recessed pocket  100  relieves the pressure from the first half  30  and the second half  40  of the handle  20  and the blade  50  to allow the first half  30  and the second half  40  to open for blade  50  change or retrieval. While the second end  160  of the fastener  140  may be integral or connected to second half  40 , preferably the fastener  140  extends through both the second half  40  and the first half  30  along a fastening axis. Closing the handle  20  merely reverses the process. 
         [0027]      FIG. 3   a  shows a preferred embodiment where the lever  110  has been lifted from the recessed pocket  100 .  FIG. 3   b  shows a preferred embodiment where the lever  110  has been lifted from the recessed pocket  100  and then rotated about the fastening axis such that the cam  120  is not directed toward the first half if the lever  110  is returned to the recessed pocket  100 . In a more preferred embodiment, the rear section  28  has an attachment hole  29  so that a cord, strap or wrist strap may be attached. 
         [0028]    The first half  30  and the second half  40  are pivotally movable in a swivel-like motion around the fastening axis between the closed position shown in  FIGS. 1 ,  2 ,  3   a  and  3   b  and the open position illustrated in  FIG. 4 . In a closed position, the first half  30  and second half  40  cooperate to form the utility knife  10  comprising a handle  20  and a blade  50 . The blade  50  may be of any kind used in utility knives, but is preferably a trapezoidal type having a notch or a plurality of notches. In the preferred embodiment shown in  FIG. 4 , the second half  40  has an inside section  200  including a forward inside section  210  having a blade rib  215  and a rear inside section  220  and at least one rear interlocking alignment rib  230 , and preferably four rear interlocking alignment ribs  230 . In this preferred embodiment, the blade  50  is mounted in forward inside section  210  such that blade rib  215  cooperates with a notch in the blade  50  to define the longitudinal projection of the blade  50  beyond the forward inside section  210  (and the forward section  22  when the handle  20  is in the closed position) such that the cutting surface of blade  50  may be used for cutting. In this preferred embodiment, additional blades  51  may be placed in the rear inside section  220  for carrying and later use.  FIGS. 7  though  10  show the preferred embodiment of the invention in cross section when closed. 
         [0029]      FIGS. 5 and 6  show exploded views of a preferred embodiment of the invention. In addition to the elements described in  FIGS. 1-4 , this preferred embodiment shows additional preferred elements and details. The preferred embodiment shown in  FIGS. 5 and 6  include the fastener  140  having a second end  160  which is round and a rectangular portion  165  extending therefrom to a cylindrical portion  166  and to the first end  150  having first end hole  155  therein and which is more preferably rounded or blunt.  FIGS. 5 and 6  additionally show the second half  40  having a second recessed portion  45  having a second slot  300  substantially perpendicular to the longitudinal axis of the second half  40  and an optionally preferred blade support  700  that can be used to clamp the blade  50  when the utility knife is to be used as a fixed, clamped blade style. More preferably the blade support  700  is made of magnetic materials such that it may removably couple with the blade  50  to hold it in place. Additionally,  FIGS. 5 and 6  show an optional spring  400 , a friction plate  500  having a friction plate slot  550  and an alignment tooth  560 , coupler  600 , and lever  110  having offset holes  132  in the cam  120  at the front end  135 . Likewise,  FIGS. 5 and 6  show the first half  30  having a first recessed portion  35  having a first slot  350  substantially parallel to the longitudinal axis of the first half  30  and adapted to receive the friction plate  500 . In this preferred embodiment, fastener  140  is of the appropriate size, except for second end  160 , to pass through, in order, the second slot  300 , the spring  400 , the first slot  350  and, the friction plate  500  such that the rectangular portion  165  is perpendicular to the longitudinal axis of the second half  40  and coupled to lever  110  such that the coupler  600  passes through both offset holes  132  and first end hole  155  such that that lever  110  is movably coupled to the fastener  140 . In this preferred embodiment, the height of the rectangular portion  165  is chosen such that when the handle  20  is in the closed position and the lever  110  is moved into the recessed pocket  100 , it is substantially perpendicular to the second slot  300  and the height is sufficient to cause the first half  30  and second half  40  to be pressed together thereby clamping the blade  50  in place. 
         [0030]      FIGS. 7 and 8  show a side view of a preferred embodiment of the invention and a longitudinal cross-section taken along the axis A-A. Similarly,  FIGS. 9 and 10  show a side view of a preferred embodiment of the invention and a transverse cross-section taken along the axis A-A.  FIGS. 11 and 12 , show an additional preferred embodiment of the second half  40  including a second recessed portion  45 , a second slot  300 , and an additional two spacing ribs  375 . In this preferred embodiment, the second slot  300  is substantially perpendicular to the longitudinal axis of the second half  40  and the spacing ribs  375  are parallel to the longitudinal axis of the second half  40  and are located on either side of the center of the second slot  300 . The spacing ribs  375  provide additional spacing for the fastener  140  by interacting with the rectangular portion  165  depending on which way the fastener  140  is turned. 
         [0031]    The utility knife  10  may be made of any material with sufficient strength such as metals, plastics or composites. The handle  20  should be made of a material with sufficient strength to transfer the clamping force to the blade  50  without collapse, but preferably a degree of flex within is desired such that the cam does not seize. More preferably, the first half  30  and second half  40  are commonly made of cast metal (aluminum or zinc), and most preferably aluminum for the light weight and feel and ability to take a variety of finishes (paint, powder coat, polish, anodizing, etc.). Preferably, the lever  110  is made of made of a molded plastic (such as nylon or glass-fiber-reinforced nylon) having the advantage of being molded in colors and are also typically inexpensive to create while holding tight tolerance. More preferably, the lever  110  is made of made of a cast metal (aluminum preferred). Preferably, the fastener  140  is made of a high tensile strength material such as metal or plastics; for example steel, aluminum or nylon material plastics. Preferably, the friction plate  500  is made of a low friction material such as metal or plastics; for example brass or bronze, or nylon or acetal (such as DELRIN) material plastics. In the preferred embodiment, the spring  400  is made of steel or other compressible material. 
         [0032]    In another preferred embodiment of this invention, the invention could also be applied to retractable-blade utility knife designs by clamping only the two halves of the knife together without clamping the blade itself-allowing the blade to be retracted without interference from the knife halves. Likewise, a variety of additional preferred embodiments of knife handle styles can be used with this same clamping means so the utility of this idea can be expanded to all sorts of existing utility knife designs. 
         [0033]    The preferred embodiment of the invention is described above in the Drawings and Description of Preferred Embodiments. While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the purview of this description are intended to be included therein as well. Unless specifically noted, it is the intention of the inventor that the words and phrases in the specification and claims be given the ordinary and accustomed meanings to those of ordinary skill in the applicable art(s). The foregoing description of a preferred embodiment and best mode of the invention known to the applicant at the time of filing the application has been presented and is intended for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in the light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application and to enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.