Abstract:
A metallic housing utility knife and method for making the device with a soft over molded elastomeric cover to provide blister free comfort and slip proof safety. The cover or skin is molded into the unique structure of the housing in a fashion that results in mechanical bonds that embrace the cover on the housing. The knife includes flexible posts from the cover that project into the blade storage compartment of the housing to prevent internally stored spare blades from moving within the storage compartment. An elastomeric blade clamp integrally formed with the cover serves to restrict lateral movement of blades of varying sizes when installed in a cutting position within the knife assembly. A rear quick release latch and interlocking housing sections provide a convenient way to open and close the knife and assure that it is also secure and firmly held when locked in a safe cutting position.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to utility knives, and more particularly to a non-retractable utility knife with a durable metallic blade carrier housing halves and an integrated soft comfortable grip.  
         BACKGROUND OF THE INVENTION  
         [0002]    Cutting implements, such as utility knives of the type in which the cutting blade is removable from the handle are well known, the combination of knife blade and handle being typically referred to as a utility knife. Such utility knives are normally available both with retractable blades, such as the type described in U.S. Pat. No. 3,192,624, and with non-retractable blades. Generally, such prior art utility knives comprise the type where two separate complimentary halves are secured together by a screw, such as the type of utility knife manufactured by Stanley Model No. 299, or the type disclosed in U.S. Pat. Nos. 2,376,887; 2,862,296; 2,948,961; 3,062,147; 3,107,426; or 3,192,624. Other prior art utility knives of the non-retractable type have been utilized which have a separate carrier member which pivots into and out of a handle, such as the type disclosed in U.S. Pat. No. 2,245,096. Some of the previously mentioned types of utility knives in which two separable halves are utilized provides for storage of replacement blades within the handle housing but often lack a means for securing these blades within the housing and they rattle around in the knife during storage and often get dull before these blades have had an opportunity to be utilized.  
           [0003]    In addition, some such prior art knives are formed of metal die cast housings with a screw to hold the handle together. While the hard die cast housings serve to make the utility knife a durable work tool, the hard surface can be uncomfortable or otherwise ergonomically undesirable leading to blisters. Maintaining a good grip is also a problem with such knives. Additional problems with such knives relates to the use of the attachment screw. Generally, since the screw is centrally located to clamp the blade, a stripped thread will have a tendency to separate the halves and become a hazard. Moreover, since they require use of a screwdriver to remove the halves, the screw makes replacing the blades more difficult and potentially less safe if one slips.  
           [0004]    Plastic injection molded utility knives have attempted to address the comfort issue by a dual molding process that combines a rigid plastic housing, typically of polypropylene, with a softer outer cover externally molded thereto, typically made from an elastomeric material such as Santoprene. The surface areas of the two materials chemically adhere due to the nature of the materials. However, these devices lack the safety, durability and feel of the heavier die cast variation as they wear quickly and the sharp blade tends to cut through. Moreover, simply molding an elastomeric material to the exterior of a metallic housing is not possible since such elastomeric material does not bond or adhere to metallic surfaces as it does with compatible plastic surfaces.  
           [0005]    Furthermore, in several of these prior art utility knives having separate halves, the portion of the cutting blade that remains in the housing has a tendency to bear against the metal of the housing when pressure is applied to the cutting edge. This typically results in the unused edge becoming dull prior to actual use of the blade.  
           [0006]    Accordingly, it is an objective of the invention to provide a non-retractable hardened utility knife with a soft, grippable and securely fixed outer cover.  
           [0007]    It is an additional objective of the invention to provide such a knife with a quick and easy means for accessing the blade storage compartment or changing the blade.  
           [0008]    It is a further objective to provide such a knife with a construction that protects the internal edge of the cutting blade from being dulled from movement when the external edge of the cutting blade is in use.  
           [0009]    It is a still further objective to provide such a device with a frontal bridge near the cutting blade to prevent the housing halves from separation during use and causing injury.  
           [0010]    It is another objective to provide such a knife with an economical and efficient method of manufacture.  
           [0011]    Additional objectives will be apparent from a review of the preferred embodiment of the invention described herein.  
         BRIEF DESCRIPTIONS OF THE INVENTION  
         [0012]    The present invention is a non-retractable utility knife with housing sections made of metal. These sections align together to form a handle and to hold a blade for cutting. The knife includes a means for releasably engaging the sections that, for preference, is a latch. This provides a way to install the cutting blade or access a blade storage compartment between the sections. A soft cover formed of an elastomeric material is mechanically retained on an exterior portion the housing sections. Preferably, the sections have rivet ports through which integrally formed molded rivets extend from the cover to retain the cover to the housing. The sections also have half channels at internal edges with tabs by which the cover is also retained. Optional flexible posts extend into the blade storage cavity to press against spare blades and impede movement of the spare blades during use of the utility knife. These posts bend as additional spare blades are stacked within. A blade clamp integrally formed with the cover protrudes against a side of the cutting blade to limit the blade&#39;s lateral movement. The housing sections interlock by tongue and groove near the cutting blade opposite the latch.  
           [0013]    The invention further includes a novel method for making the utility knife housing. The method involves casting the utility knife housing in a first mold with molten metal such as zinc or aluminum. A mold in this die casting process includes mechanical or structural features to shape the housing for retaining a subsequently formed soft cover around the housing. In the subsequent injection molding process, the soft cover and its integrated features are then formed directly onto the previously die cast knife housing. The mold in this second process receives the utility knife housing and the soft cover is subsequently formed by injection molding an elastomer to and around the inner knife casting. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a top elevation view of a utility knife assembly of the invention;  
         [0015]    [0015]FIG. 2 is a side elevation view of the utility knife assembly of FIG. 1;  
         [0016]    [0016]FIG. 3 is an internal elevation view of a mount side of the housing of the assembly of FIG. 1 with blades and latch inserted;  
         [0017]    [0017]FIG. 4 is an elevation view of a quick release latch from the embodiment of the invention of FIG. 1.  
         [0018]    [0018]FIG. 4A is a top plan view of the quick release latch of FIG. 4.  
         [0019]    [0019]FIG. 4B is a sectional view of the latch of FIG. 4 taken along line A-A of FIG. 4.  
         [0020]    [0020]FIG. 4C is a side plan view of the quick release latch of FIG. 4.  
         [0021]    [0021]FIG. 5 is an external elevation view of a mount side of the housing of the assembly of FIG. 1 with soft outer cover;  
         [0022]    [0022]FIG. 6 is a top elevation of the mount side of FIG. 5;  
         [0023]    [0023]FIG. 7 is an internal elevation view of the mount side of FIG. 5;  
         [0024]    [0024]FIG. 8 is a sectional view of the mount side of FIG. 7 taken along line F-F of FIG. 7.  
         [0025]    [0025]FIG. 9 is a sectional view of the mount side of FIG. 7 taken along line D-D of FIG. 7.  
         [0026]    [0026]FIG. 10 is a sectional view of the mount side of FIG. 7 taken along line E-E of FIG. 7.  
         [0027]    [0027]FIG. 11 is a sectional view of the mount side of FIG. 7 taken along line B-B of FIG. 7.  
         [0028]    [0028]FIG. 12 is an elevation view of the mount side of FIG. 7 in the direction of sight of arrow G of FIG. 7.  
         [0029]    [0029]FIG. 13 is a sectional view of the mount side of FIG. 7 taken along line C-C of FIG. 7.  
         [0030]    [0030]FIG. 14 is an internal elevation view of a release side of the housing of the assembly of FIG. 1 with soft outer cover and soft inner projections;  
         [0031]    [0031]FIG. 15 is a top elevation of the release side of FIG. 14;  
         [0032]    [0032]FIG. 16 is a external elevation of the release side of FIG. 14;  
         [0033]    [0033]FIG. 17 is a sectional view of the release side of FIG. 14 taken along line H-H of FIG. 14;  
         [0034]    [0034]FIG. 18 is a sectional view of the release side of FIG. 14 taken along line K-K of FIG. 16;  
         [0035]    [0035]FIG. 19 is a sectional view of the release side of FIG. 14 taken along line J-J of FIG. 16;  
         [0036]    [0036]FIG. 20 is a sectional view of the release side of FIG. 14 taken along line I—I of FIG. 16;  
         [0037]    [0037]FIG. 21 is an elevation view of the release side of FIG. 14 in the direction of sight of arrow N of FIG. 16;  
         [0038]    [0038]FIG. 22 is a sectional view of the release side of FIG. 14 taken along line L—L of FIG. 16;  
         [0039]    [0039]FIG. 23 is a partial sectional view of the release side of FIG. 14 taken along line M—M of FIG. 16;  
         [0040]    [0040]FIG. 24 is an external elevation view of the mount side of FIG. 5 before a soft outer cover is molded to it;  
         [0041]    [0041]FIG. 25 is a top elevation of the mount side of FIG. 24, casting only;  
         [0042]    [0042]FIG. 26 is an internal elevation view of the mount side of FIG. 24;  
         [0043]    [0043]FIG. 27 is a sectional view of the mount side of FIG. 24 taken along line O-O of FIG. 26;  
         [0044]    [0044]FIG. 28 is a sectional view of the mount side of FIG. 24 taken along line R-R of FIG. 26;  
         [0045]    [0045]FIG. 29 is a sectional view of the mount side of FIG. 24 taken along line S-S of FIG. 26;  
         [0046]    [0046]FIG. 30 is a sectional view of the mount side of FIG. 24 taken along line P-P of FIG. 26;  
         [0047]    [0047]FIG. 31 is an elevation view of the mount side of FIG. 24 in the direction of sight of arrow T of FIG. 26;  
         [0048]    [0048]FIG. 32 is a sectional view of the mount side of FIG. 24 taken along line Q-Q of FIG. 26;  
         [0049]    [0049]FIG. 33 is an internal elevation view of the release side of FIG. 14 without an overmolded soft outer cover;  
         [0050]    [0050]FIG. 34 is a top elevation of the release side of FIG. 33, inner casting only;  
         [0051]    [0051]FIG. 35 is an external elevation view of the release side of FIG. 33;  
         [0052]    [0052]FIG. 36 is a sectional view of the release side of FIG. 33 taken along line Y-Y of FIG. 35;  
         [0053]    [0053]FIG. 37 is a sectional view of the release side of FIG. 33 taken along line W-W of FIG. 35;  
         [0054]    [0054]FIG. 38 is a sectional view of the release side of FIG. 33 taken along line V-V of FIG. 35;  
         [0055]    [0055]FIG. 39 is a sectional view of the release side of FIG. 33 taken along line U-U of FIG. 35;  
         [0056]    [0056]FIG. 40 is an elevation view of the release side of FIG. 33 in the direction of sight of arrow AA of FIG. 35;  
         [0057]    [0057]FIG. 41 is a sectional view of the release side of FIG. 33 taken along line X-X of FIG. 35;  
         [0058]    [0058]FIG. 42 is a partial sectional view of the release side of FIG. 33 taken along line Z-Z of FIG. 35. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0059]    With reference to FIGS. 1 and 2, a utility knife assembly  2  of the invention includes a housing  4 , a gripping cover  5  and a quick release latch  6 . Generally, the housing  4  is configured to serve as a handle and secure a cutting blade in a cutting position extending into and from the housing  4  at a cutting portion  8  of the housing  4 . The housing  4  has two corresponding housing sections with complementing structures. When joined by the latch  6 , the two sections form the knife assembly  2 . The housing sections include a mount side  10  and a release side  12 . These housing sections are joined by interlocking structures at the cutting portion  8  of the housing  4  and by the quick release latch  6  at a latching portion  14 . The housing  2  is preferably made of a die-cast metal, such as zinc or aluminum or other moldable metal alloy, to form a hard, durable handle for the utility knife assembly  2 . The gripping cover  5  is made from a soft molded elastomer such as Santoprene. The latch  6  is a preferably firm resilient engineering plastic with some limited flexibility, e.g., Celcon acetal resin, Lexan polycarbonate or nylon.  
         [0060]    The quick release latch  6  provides a means for releasably engaging the housing sections at the latching portion  14 . FIGS. 4, 4A,  4 B and  4 C depict one embodiment of the latch  6  in detail. The latch  6  is molded to complement related structural features of the housing sections. The latch  6  includes locking tabs  16  extending from the latch base  22  for fixing the latch  6  to the mount side  10  of the housing  4 . The latch  6  includes a latching tongue  18  to releasably engage with the release side  12  of the housing  2 . The latching tongue  18  is adjacent to a finger tab  20 . The latching tongue  18  has a beveled side  18 B opposite a latching side  18 L.  
         [0061]    The finger tab  20  is incorporated to the latch base  22  by a flexing support  24 . The finger tab  20  extends from the flexing support  24  to form a lever such that when a pushing force is applied to the finger tab  20  when the latch base is fixed to the housing  4 , the flexing support  24  bends elastically in a lateral direction. With such bending, the latch  6  can release the engagement of the two sections as the latching tongue  18  moves. Similarly, the beveled side  18 B serves to convert a closing force into a lateral bending force on the flexing support  24  of the latch  6  as a housing section is forced against the bevel when the assembly  2  is manipulated from its open position to its closed position. Since the latch  6  is made from a firm material with limited flexibility, after bending of the flexing support  24 , it will return to its original molded unbent configuration to securely engage the housing sections when the assembly is in the closed position.  
         [0062]    As previously noted, the housing  4  includes a mount side  10 . The mount side  10  is generally depicted in FIGS.  3 ,  5 - 13  with the cover  5  molded thereon and in FIGS.  24 - 32  before molding the cover thereon. The mount side  10  includes blade ledges  26  and a blade positioning tab  28  to align a cutting blade  30  in a non-retractable position at the cutting portion  8 . The mount side  10  of the housing  4  also has a mounting aperture  32  and mounting studs  34  at the latching portion  14 ′ The mounting aperture  32  is sized to lock on the locking tabs  16  of the latch  6  such that ridges of the locking tabs  16  engage the external surface edges  33  of the mounting aperture  32  when the locking tabs  16  are inserted therein. The mounting studs  34  are positioned and sized to reside in corresponding holes in the latch base  22 .  
         [0063]    The mount side  10  preferably includes a blade store cavity  36  to retain spare blades  38 . At the cutting portion  8 , the mount side  10  includes opposing grooves  40 . The grooves  40  serve to interlock the mount side  10  to the release side  12  when these housing sections are joined. The cutting blade  30  passes through the grooves  40  when installed in a non-retractable cutting position in the assembly  2 .  
         [0064]    The mount side  10  has several features designed to mechanically secure a portion of the gripping cover  5  to the housing  4  at the mount side  10 . At a portion of the internal edges of the mount side  10  are half channels  42  with several cover holding tabs  44 . The half channels  42  serve as a mold to receive the part of the gripping cover  5  attached to the mount side. Since the half channels  42  surround the holding tabs  44 , the gripping cover  5  is retained by the cover holding tabs  44 . The mount side  10  also includes rivet ports  46  to receive molded rivets  48  that are integrally formed with the gripping cover  5 . The molded rivets  48  are formed within the housing  4  so that the head portion of each rivet within the housing  4  is larger than the rivet ports  46  and resides next to each rivet port. This serves to keep the molded rivets  48  from moving or passing out through the rivet ports  46  to thereby assist with holding the gripping cover  5  on the housing  2 .  
         [0065]    The release side  12  of the housing  4  is depicted in FIGS.  14 - 23  with the cover  5  and in FIGS.  33 - 42  prior to the molding of the cover  5  thereon. The release side  12  has a structure to interlock with the grooves  40  of the mount side  10  and a structure to releasably engage with the latch  6  at the latching tongue  18 . At a cutting portion  8  the release side  12  has mating tongues  50  arranged to reside within the grooves  40  and interlock therewith. The release side  12  further has a latch aperture  52  to receive the finger tab  20 . A latching tongue indent  54  lies adjacent to the latch aperture  52 . The external surface of this latching tongue indent  54  engages with the latching tongue  18  at the latching side  18 L to releasably engage the housing sections when the housing sections are aligned and interlocked with the mating tongues  50  in the groves  40  and when the latch  6  is in the latch aperture  52 . This configuration corresponds with the assembly  2  being in its closed position.  
         [0066]    The release side  12  of the housing  4  also includes a half channel  42  along a portion of its edges as well as several rivet ports  46 . The channels also include several cover holding tabs  44  to mechanically hold the portion of the gripping cover  5  on the release side  12  of the housing  4  in a similar fashion as that of the portion of the gripping cover  5  on the mount side  10  of the housing  4 . Preferably, the half channels  42  from each housing section are aligned at internal edges so that they reside between the housing sections when the assembly  2  is in its closed position. Additionally, opposing cover holding tabs  44  on the opposing housing sections may also be aligned with each other. These alignments provide for an additional mechanical hold on the gripping cover  5  by holding the edges of the gripping cover  5  between the closed housing  4  and inhibiting the gripping cover from being pulled over the cover holding tabs  44  within each half channel  42  as the opposing cover holding tabs  44  contact or otherwise reside near each other when the housing  4  is closed.  
         [0067]    As an integral part of the portion of the gripping cover  5  on the release side  12 , flexible posts  56  protrude beyond the cavity of the release side, extending well into the blade store cavity  36  of the mount side  10  of the housing  2 . These flexible posts  56  provide a means to prevent movement of the spare blades  38 . When the assembly  2  is in its closed position with spare blades  38  enclosed in the blade store cavity  36 , the flexible posts  56  press against one or more spare blades  38 . Since they are flexible, the protruding posts will bend but still apply pressure against the spare blades  38 . As the stack reduces in height, the flexible posts  56  straighten to accommodate a varying number of spare blades. With this device, the spare blades  38  within the housing will not rattle regardless of the number of spare blades. This also serves to prevent the spare blades  38  from becoming dull as a result of being jostled against the internal structures of the housing  2  during use. To enable the flexible posts  56  to also serve a function of holding the gripping cover  5  to the housing  4 , at their base the flexible posts  56  include molded rivets  48  to impede the flexible posts  56  from passing out through the rivet ports  46 . Thus, these flexible molded rivets  48  secure the outer soft gripping cover  5  to the cast housing  4  on the release side  12 . Conversely, since the gripping cover  5  is formed integrally with the flexible posts  56 , the gripping cover  5  through one or more rivet ports  46  serves to secure the flexible posts  56  to the release side  12 .  
         [0068]    As shown in FIGS. 14 and 17, a flexible blade clamp  58  is another integral feature of the gripping cover  5  that extends within the release side  12  of the housing  4 . In conjunction with the blade positioning tab  28  and the blade ledges  26 , the flexible blade clamp  58  assists in securing the cutting blade  30  in a cutting position in the assembly  2 . More specifically, the blade clamp  58  provides for lateral support of the cutting blade between the housing sections. In the preferred embodiment of the blade clamp  58 , three protrusions extend toward the blade a sufficient distance to flexibly apply pressure or squeeze against the cutting blade  30  when the assembly  2  is in its closed position to limit lateral movement of the cutting blade. The flexible nature of these protrusions permits blades of varying sizes to be held firmly. Moreover, since the blade clamp  58  is integrally formed with the gripping cover  5  through one of the rivet ports  46  of the release side  12 , its location inside the housing  4  serves the further purpose of providing an additional mechanical hold on the gripping cover  5  to keep the gripping cover  5  fixed to the housing  4 . An additional hold down pin  59  formed as an integral part of the flexible blade clamp  58  resides in a pin port  60  in the release side  12  of the housing  4 .  
         [0069]    In use the assembly  2  provides a safe, sturdy and functional utility knife. From its closed position, the assembly  2  may be opened by pressing the user&#39;s finger against the finger tab  20 , to force the latching tongue  18  away from its contact at the latching side  18 L with the latching tongue indent  54  of the release side  12  of the housing  2 . Upon release, the release side  12  may be separated from the mount side  10  by withdrawing the mating tongues  50  of the release side  12  from the grooves  40  of the mount side  10  at the cutting portion  8  of the housing  4 . A spare blade  38  can be removed from the blade store cavity  36 . The blade can then be placed on the blade ledges  26  on the blade positioning tab  28  under the grooves  40  at the cutting portion  8  of the mount side  10  of the housing  4 .  
         [0070]    To close the assembly  2 , the mating tongues  50  of the release side  12  are inserted into the grooves  40  of the mount side  10 . The release side  12  may then be aligned so that the latch aperture  52  of the release side  12  moves over the finger tab  20  of the latch. As the release side  12  and mount side  10  are pressed together, the latching tongue  18  moves away from the latching tongue indent  54  as the release side traverses the surface of the beveled side  18 B of the latching tongue  18  on the latch  6 . Simultaneously, the flexible posts  56  from the release side  12  are forced to bend against any remaining spare blade  38  in the blade store cavity  36  of the mount side  10  of the housing  4 . Similarly, the flexible blade clamp  58  is forced against the cutting blade  30 . When the latching tongue indent  54  passes the latching side  18 L of the latching tongue  18 , the latching tongue will return to its unbent position to contact the surface of the latching tongue indent  54 , thereby engaging the release side  12  and the mount side  10  of the housing  4 .  
         [0071]    Once locked closed, the assembly  2  may be used for cutting by grasping the assembly at the gripping cover  2 . Since the gripping cover  2  is mechanically attached to the housing  4  by (a) the flexible blade clamp  58 , (b) the molded rivets  48 , (c) edge portions of the cover residing in the interior aligned half channels  42  and looped around or otherwise surrounding the cover holding tabs  44 , the gripping cover  2  provides a firmly retained, non-slip outer skin for ergonomic comfort.  
         [0072]    Despite the intricacies of the combined features of the assembly, a unique manufacturing process may be followed to reduce assembly of the various features during manufacture of the invention. To this end, while the gripping cover  5 , the blade clamp  58 , the flexible posts  56  and the molded rivets  48  may be manufactured as separate components and combined in a final assembly with all or some of the components, it is preferred to have some or all of these features applied to the housing sections of the housing  4  in a common process. Thus, the invention includes a methodology in which the internal and external soft structural features of the gripping cover  2  are manufactured onto either housing section in a single injection molding process.  
         [0073]    The steps to accomplishing the method include the preparation of corresponding housing sections in a mold or molds. The molds include the reverse shapes of the separate housing sections of the utility knife particularly with the structural features for fastening or retaining the gripping cover  5  on exterior portions of the housing  4 . Thus, a mold is optionally made to include half channels  42 , cover holding tabs  44 , and/or rivet ports  46 . Those skilled in the art would understand the steps of creating such a mold. With one or more of such molds, the housing sections are cast in a first metal casting process by pressure casting molten metal into the mold.  
         [0074]    Similarly, one or more molds are made to receive each cast metal housing section. The molds have reverse shapes to correspond with the surface of the gripping cover  2  and its integrated parts such as the interior retaining portions that hold the gripping cover  5  to the housing  4 . Thus, the preferred release side  12  mold would include structures for forming internal features including barriers for the portion of the gripping cover  5  in the half channels  42 , the interior portions of the blade clamp  58 , the interior portions of the flexible posts  56  and the interior portions of the molded rivets  48 . The preferred mount side  10  mold would include barriers for the portion of the gripping cover  5  in the half channels  42  and the interior portions of the molded rivets  48 . Of course, due to the structures of the mount side  10  and the release side  12  which will be included in the molding process, these housing sections themselves serve as an important part of the structure of the mold. In the secondary elastomer molding process, the gripping cover  5  with its incorporated features is cast by injecting an elastomer as a hot liquid into each mold with a corresponding housing section contained therein. The liquid elastomer then moves over an exterior cover portion of the housing section, through the various rivet ports  46  and into the half channels  42  of the housing section to form the gripping cover  5  with its integrated features. The latch  6  formed from another mold may then be installed in the cooled housing sections by attaching one to a mount side  10  and a release side  12 .  
         [0075]    Basically, the tool ends up being an extremely simple and safe two-piece knife with a soft and comfortable grip. It is safe as the user&#39;s hand does not slip. It is convenient as the cutting blade can be changed readily without the use of a screwdriver or other tool. It is accurate since the blade is clamped during use and cuts straight. It is strong since the blade will not move during cutting. Its razor sharp spare blades do not shake or dull during use or transport, thereby promoting safety. A sharp blade is a safe blade. In its preferred form, it is the only two-piece non-retractable utility knife without loose or moving parts.  
         [0076]    Although the invention is described in terms of a particular embodiment, it is to be understood that the embodiment is merely illustrative of an application of the principles of the invention. Numerous modifications may be made and other arrangements may be devised without departing from the spirit and scope of the invention as defined by the claims. For example, although a latch is the preferred means for releasably engaging the other housing sections, alternatives might be used for example, a screw.