Abstract:
A utility knife comprising a casing, a blade holder moveably mounted within the casing, said blade holder being moveable incrementally from a fully extended position outside the casing to a fully retracted position inside the casing whereby the blade holder may be positioned in a partially extended position.

Description:
BACKGROUND  
       [0001]     The present invention relates to a utility knife and more particularly to a utility knife in which the blade may be moved into the handle when the knife is not in use.  
         [0002]     Utility knives have been in use for a number of years. Some of these utility knifes have blades which are moveable within a handle when the knife is not in use. However, a number of these utility knives have many movable parts which makes them difficult to use and expensive to manufacture. In some of these utility knives replacement of the blade is a complicated operation which may required the use of special tools. Moreover, some existing utility knives do not have means to permit the blade to be only partially moved out of the handle nor do they have the ability to incrementally move the blade in and out of the handle.  
       OBJECTS  
       [0003]     The present invention overcomes these problems and has for one of its objects the provision of an improved utility knife in which the blade may be easily moved into the handle.  
         [0004]     Another object of the present invention is the provision of an improved utility knife in which the blade is held securely on a blade holder.  
         [0005]     Another object of the present invention is the provision of an improved utility knife in which the blade moves easily to any position within the handle.  
         [0006]     Another object of the present invention is the provision of an improved utility knife in which the blade may be moved incrementally in and out of the handle.  
         [0007]     Another object of the present invention is the provision of an improved utility knife which is simple to use and inexpensive to manufacture and maintain.  
         [0008]     Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment described, or will be indicated in the appended claims and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. 
     
    
     DRAWINGS  
       [0009]     A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification, wherein:  
         [0010]      FIG. 1  is an exploded perspective view of a utility knife made in accordance with the present invention.  
         [0011]      FIG. 2  is a perspective view of the assembled utility knife of the present invention.  
         [0012]      FIG. 3  is a top plan view thereof.  
         [0013]      FIG. 4  is a sectional view taken along the line  4 - 4  of  FIG. 2 .  
         [0014]      FIG. 5  is an enlarged fragmentary sectional view of the blade moving mechanism of the present invention.  
         [0015]      FIG. 6  is a fragmentary side view of the knife as shown in  FIG. 5 .  
         [0016]      FIG. 7  is a sectional view taken along lines  7 - 7  of  FIG. 5 .  
         [0017]      FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 4 .  
         [0018]      FIG. 9  is a sectional view similar to  FIG. 4  showing the blade holding mechanism.  
         [0019]      FIG. 10  is an enlarged detail of the blade holding mechanism in the blade locking position.  
         [0020]      FIG. 11  is an enlarged detail similar to  FIG. 10  showing the blade holding mechanism in its blade unlocking position.  
         [0021]      FIG. 12  is an enlarged fragmentary sectional view showing the removal of the blade.  
         [0022]      FIG. 13  is a side elevational view of knife of the present invention from one side.  
         [0023]      FIG. 14  is a side element view of the knife of the present invention from the other side.  
         [0024]      FIG. 15  is an enlarged fragmentary sectional view showing the blade storage compartment of the present invention. 
     
    
     DESCRIPTION  
       [0025]     Referring to the drawings, the utility knife  1  of the present invention comprising a first casing  2 A half and a second casing half  2 B which are assembled together to form the complete casing  2 . Both casing halves  2 A and  2 B have respectively, a side wall  3 A and  3 B, a top wall  4 A and  4 B, a bottom wall  5 A and  5 B a rear wall  6 A and  6 B and an open mouth  7 A and  7 B. The casing halves  2 A and  2 B are mounted together by any well known means, such as a fastener  17  to form top wall  4 , bottom wall  5  and rear wall  6  and open mouth  7 . The front ends of  8 A and  8 B of the two casing halves  2 A and  2 B are reduced so that when the casings  2 A and  2 B are mounted together a front end  8  of reduced dimension is formed. A mouth assembly  10  having a front wall  11  with a slit  14 , an open bottom  15 , end walls  12  and side walls  13  is mounted over the front ends  8 A and  8 B of the casing  2  together. A lock button  16  may be provided in the front end  8 B adapted to be inserted into an opening  17  in a side wall  13  of the mouth assembly  10  in order to lock the mouth assembly  10  in place over the casing end  8 . Thus, the two casings  2 A and  2 B are held together by the mouth assembly  10  held in place by the lock bottom  16  at the front and fastener means  18  at the rear of the casings  2 A and  2 B.  
         [0026]     Mounted within the casing  2  are drive worm gear  30  and a drive worm gear  20 . The worm gears  30  and  20  have front and rear ends  30 A and  30 B and  20 A and  20 B mounted in the joint  20  and  30 . Each worm gear  20  and  30  has an interconnecting gear wheel  22  and  32  mounted on its rear ends  20 A and  30 A which are adapted to mesh with each other so that when the drive worm gear  30  rotates the driven worm gear  20  will also rotate. In the drawings the worm gears  20  and  30  are shown as being located within the casing  2  so that the drive worm gear  30  is located in casing half  2 A and driven worm gear  20  is in the second casing half  2 B thereby positioning the worm gears  20  and  30  in a side-by-side relationship. However, it will be understood that the positions of the worm gears  20  and  30  can be changed as long as the drive worm gear  30  and the driven worm gear  20  are mounted to permit their gear wheels  32  and  22  to mesh with each other. The drive worm gear  30  gear has a thread gauge  33  larger than the thread gauge  23  of the driven worm gear  20 .  
         [0027]     A finger slide button assembly  40  is slidably mounted in the side wall  3 A through a slot  41  in said side wall  3 A. The finger slide button assembly  40  has a finger  42  extending inwardly and meshing with the thread  33  of the drive worm gear  30 . It is seen that when the finger slide button  40  is moved back and forth along the slot  4 , the finger  42  slides in the thread  33  of the drive worm gear  30  to rotate the drive worm gear  30  in either direction. Since the drive wheel  32  at the rear of the drive worm gear  30  meshes with the drive wheel  22  at the rear of the driven worm gear  22 , rotation of the drive worm gear  30  will rotate the driven worm gear  20 .  
         [0028]     A blade carrier assembly  50  is provided to receive a blade B. The blade B has a lower cutting edge  60  and notches  61  in its upper edge  62 . The blade carrier assembly  50  comprises a flat body portion  51  having upper and lower walls  52  and  53  which are substantially parallel to each other and extend from the body portion  51  at a right angle thereto. A rear wall  54  is also provided. The body portion  51  is shown as being shaped substantially like a parallelogram, however it will be understood that the body portion  51  may be shaped differently, such as rectangular, etc. The upper wall  52  of the blade carrier assembly  51  has a notch  55  therein. The blade carrier assembly  50  also has fingers  56  extending thereafter which enter and mesh with the thread  23  of the driven worm gear  20  so that when that worm gear  30  is rotated, the blade carrier  50  will move along the thread  23  to the driven worm gear  20 .  
         [0029]     A resilient blade lock assembly  70  is mounted on one side (preferably the outside) of the blade carrier and is held there by fasteners  57 . The blade lock assembly  70  comprises a resilient bar  71  having a release finger  72  and a blade holding finger  73  extending at right angles therefrom. The blade holding finger  72  extends through the notch  55  in the blade carrier  50  and into a notch  61  in the blade B. The release finger  72  is longer than the blade holding finger  73  and is at a higher level than the level of the blade holding finger  73  so that it extends over the top wall  52  of the blade carrier  50  for a distance greater than the blade holding finger  73 . The support bar  70  in its unflexed position lies against the outside of the blade carrier  50  with the blade holding finger  73  extending into a notch  61  in the blade B and the release finger  72  extending over the top wall  54  of the blade carrier  50 . In this manner the blade B is held in place. on the blade carrier  50 .  
         [0030]     It will thus be seen that when the finger slide button assembly  40  is moved back and forth along slot  41 , the drive worm gear  30  is rotated back and forth. This in turn rotates the driven worm gear  20  which allows the blade carrier  50  to move back and forth thereby extending or retracting the blade B to its full extent or only partially between a fully extended position and a fully retracted position. This movement of the blade B is variable depending on the forward and backward movement of the finger slide button assembly  40 .  
         [0031]     A spring pressed blade ejection button assembly  80  is mounted at the front of the casing and is biased outwardly by a spring  82  and is provided with an inner edge  81 . The spring pressed button assembly  80  is at the same level as the blade release finger  72  extending from the resilient release bar  70 . When it is desired to remove or replace the blade B, the blade B is placed in its most forward position so that it protrudes fully from the slit  11  in mouth  10 . At this point, the inner edge  81  of the ejection button  80  is adjacent the blade release finger  72 . When the blade ejection button  80  is pressed inwardly against the bias of the spring  82 , its inner edge  81  strikes the release finger  72  and moves it inwardly. This flexes the resilient support bar  70  inwardly away from the body  50  to move the blade holding finger  73  inwardly out of the upper notch  61  in the blade B. This releases the blade B and the blade B can then be removed manually through the slit  11  in the mouth.  
         [0032]     Replacement of the blade B may be accomplished in the same manner by pushing the ejection button  80  inwardly to move the release finger  72  and the blade holding finger  73  inwardly. The blade B is then slid into the blade carrier  50  through the slit  14  in the mouth  10 . When the ejection button is released the bar  70  springs back to its original position and the blade holding finger  73  moves into the notch  61  of the blade B to hold it in place.  
         [0033]     A blade storage compartment S also is provided at the rear of the casing half  2 A to accommodate a plurality of spare blades B. The side wall  3 A of the casing  2 A has an opening top  90  in its side wall  3 A which is adapted to be closed by a cover assembly  91 . A front portion  91 A of the cover assembly  91  is pivotally mounted to the wall of the casing half  2 A my means of a pivot assembly  92 . The cover assembly  91  has a top surface  93  with a side skirt  94  depending from the top surface  93 . The side skirt  94  has a lower curved convex edge  95  which conforms to and mates with the concave edge  96  in the open top  90  of the side wall  3 A when the cover assembly  91  is in its closed position.  
         [0034]     The rear portion  91 B of the cover assembly  91  also has a hook  97  extending downwardly therefrom. A latch assembly  100  is provided on side wall  3 A with a finger button  101  extending through an opening  102  in the sidewall  3 A. A lock bar  103  is spring pressed in an inward position so that it is normally positioned over the hook  97  to keep the cover assembly  90  in its closed position. When the lock bar  103  is moved by the finger button against a spring (not shown) in a forward direction it is moved from beneath the hook  97  to release the cover assembly  90  and to permit it to open. If desired, a spring mechanism  105  may be applied to the cover assembly so that it causes the cover assembly  90  to spring up under the influence of the spring  105  when the lock bar  102  is released from under the hook  97 . In order to close the blade storage compartment S, the cover  90  is moved down against the bias to the spring  105  until the hook  97  snaps under the lock bar  102  to hold the cover assembly  90  of the blade storage compartment S in a closed position. A plurality of blades B may be stored within the blade storage compartment S, each of which can be removed when it is desired to replace an old blade with a new blade B.  
         [0035]     In operation, a blade B is located on the blade carrier  50  which has fingers  56  meshing with thread  23  of the driven worm gear  20 . The slide finger  40  is positioned in the slot  41  of the side wall  3 A and has its finger  43  meshing with the thread  33  of the driving worm gear  30 . When the slide finger  40  is moved forward or backward the driving worm gear  30  is rotated to rotate the driven worm gear  33  through the intermediation of the toothed gear wheel  32  and  22  at the rear of each worm gear  30  and  20 , respectively. The rotation of the driven worm gear  20  causes the blade carrier  50  to move along the threads  23  of the driven worm gear  20 . It will thus be seen the slide finger  40  may move the blade B all the way forward or all the way back or anywhere in between so that the amount of exposure of the blade B out of the slit  11  may be varied.  
         [0036]     When it is desired to remove and replace a blade B the ejection button  80  is pushed inwardly. This moves the ejection finger  72  of the resilient bar  70  inwardly away from the blade carrier  50  which in turn moves the blade holding finger  73  out of the notch  61  in the blade B thereby permitting the blade B to be slid out of the slit  11  in the front face  14  and a new blade B to be slid into the front of slot  14 .  
         [0037]     It will thus be seen that the present invention provides and improved utility knife in which the blade holder may be easily moved into the handle, in which the blade is held securely on the blade holder, in which the blade moves easily to any position in which the blade may be moved variably in and out of the handle.  
         [0038]     As many and varied modifications of the subject matter of this invention will become apparent to those skilled in the art from the detailed description given hereinabove, it will be understood that the present invention is limited only as provided in the claims appended hereto.