Abstract:
A folding tool has a monolithic, one-piece handle with an implement rotationally mounted to the handle for rotational movement between a closed, stored position and an open, use position. The handle is adapted for installation of bearings on both sides of the implement following a defined method of installation so that the implement rides on bearings as it is rotated relative to the handle.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to tools that have implements foldably attached to a one-piece handle, and especially tools such as knives in which the blade is foldably attached to a one-piece handle. 
       BACKGROUND 
       [0002]    Unitary, one-piece handles for knives have become increasingly more popular with consumers. There appear to be a variety of reasons for the uptick in interest in knives and other tools with one-piece handles, including aesthetics, strength and functionality. At the same time, some knife makers are using a variety of types of bearings around the pivot shaft where the knife blade is foldably and rotatably attached to the handle. Bearings have obvious functional benefits in such situations since they smooth the rotational movement of the blade from closed to open, and vice versa and they also reduce the amount of force required to rotate the blade. 
         [0003]    Conventional folding knives have handles that have opposed sidewalls or handle halves that are attached together with a space between the opposed sidewalls—the blade receiving groove is located in the space between the sidewalls. The blade is rotatably attached to the two handle halves with a pivot shaft that extends through a tang portion of the blade. As the blade rotates between closed and open, open and closed, the blade rotates about the pivot shaft. A variety of spacers and screws are used to attach the handle halves together. In such construction, installing bearings around the pivot shaft is a relatively simple task during assembly of the knife because the bearings can be installed as the handle halves are being connected with the pivot shaft and blade. 
         [0004]    However, when the handle is a monolithic unit that has a blade groove in the unitary piece, installation of bearings around the pivot shaft is very difficult because the sidewalls of the handle cannot be separated. 
         [0005]    There is a need therefore for apparatus and methods that allow bearings to be installed around the pivot shaft of a knife having a one-piece handle. The present invention defines such apparatus and method. Those of skill in the art will readily recognize that while the invention is enabled with respect to a specific type of knife, the invention is not limited to knives but extends to any tool having a one-piece handle with an implement rotatably attached to the handle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention will be better understood and its numerous objects and advantages will be apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings in which: 
           [0007]      FIG. 1  is a perspective view of a type of knife sold by the assignee of the present invention under the trademark BALI-SONG and in which the two handles of the knife are formed in unitary, monolithic pieces and in which the present invention is embodied; in  FIG. 1  the blade of the knife is in the closed position between the two handles. 
           [0008]      FIG. 2  is a side elevation view of the knife of  FIG. 1  and in which the two unitary handles and the blade have been manipulated in order to move the blade into the open position. 
           [0009]      FIG. 3  is a perspective and exploded view of one part of one handle of the knife shown in  FIG. 1 , and more specifically, is an exploded view of the end of one handle to which the blade is attached. 
           [0010]      FIG. 4  is a cross sectional view taken along the line  4 - 4  of  FIG. 2 . 
           [0011]      FIG. 5  is a cross sectional view of an alternative embodiment of an invention according to the present similar to the cross sectional view of  FIG. 4  and taken along the same sectional line of a knife in which the alternative embodiment is incorporated as the knife of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    One specific knife that consumers have expressed a strong desire for a one-piece handle is the BALI-SONG knife such as the knife  10  shown in  FIG. 1 . In  FIG. 1  the blade  12  is in the closed position in which the blade is safely stowed between the handle halves. The BALI-SONG knife  10  is a well-known tool in which the single blade  12  is pivotally attached to two separate handle halves  14  and  16 . The blade  12  is pivotally attached to each handle half  14  and  16  separately at the tang end  18  of the blade with two separate pivots, labelled  20  and  22  in  FIG. 1 . Use of such a knife  10  is an art and combat form well known to connoisseurs of these tools. 
         [0013]    In the embodiment of knife  10  described herein and shown in the drawings, each of the handle halves  14  and  16  re fabricated as a one piece monolithic unit. In a preferred embodiment the handle halves are machined from aluminum. However, it will be appreciated that there are numerous equivalent methods of forming a unitary handle half and the handles may be formed from a variety of materials such as titanium, G10, etc. 
         [0014]    With reference now to  FIG. 2  the blade  12  is extended into the extended or working position. Manipulation of the blade  12  and the handle halves  14  and  16  to move the blade/handles between the closed position of  FIG. 1  and the open position of  FIG. 2  is well-known to those of skill in the art, and as noted above, use of the knife is an art form. Smooth rotational movement of the blade relative to the handles is very important and enhances greatly the manipulation of the knife  10  by users. Said another way, if frictional drag between the pivot shafts that interconnect the blade to the handles is significant, manipulation of the knife according to time honored techniques is impeded. Accordingly, knife makers have always strived to reduce the rotational friction between the blade and the handles. 
         [0015]    The apparatus and method of the present invention relates to the dual pivot axes  20  and  22  that attach the blade  12  to the two handle halves  14  and  16 . Again, it will be understood that each of the two handle halves  14  and  16  is a monolithic piece. Each of the handle halves includes a longitudinal blade slot  24  into which the blade is received when the knife  10  is in the closed position. In cross section, each of the two handle halves defines a substantially U-shaped member where the blade is received in the U-shaped blade slot  24  when in the closed position. In  FIG. 1  the longitudinal slots  24  are facing one another; in  FIG. 2  the longitudinal slots  24  face outwardly since the relative positions of the handle halves is reversed when the blade  12  is in the open or extended position. 
         [0016]    Reference is now made to  FIG. 3 , which is a perspective and exploded view of one end of one handle half, in this case handle half  14 , illustrating the components of the blade-to-handle pivot in exploded orientation. More specifically,  FIG. 3  is a close up perspective and exploded view of the end labelled with reference number  26  in  FIG. 2 , with the components that comprise pivot axis  20  exploded in the view of  FIG. 3 . 
         [0017]    In the assembled knife  10 , the tang end  18  of blade  12  is inserted into the tang slot  28  in handle half  14  and is pivotally attached thereto with the components that define the pivot axis  20 . The tang slot  28  is defined by two sides of handle half  14 , one on either side of tang slot  28  and labelled with reference numbers  30  and  32  in  FIG. 3 . A bore  34  having a diameter X is formed through side  32 . A blind counter bore  36  is formed in the interior surface  38  of side  30 ; blind counter bore  36  is axially aligned with bore  34  and has a diameter X identical to of closely similar to the diameter X of bore  34 . It will be understood by those of skill in the art that the diameter of the bores and other structures identified herein as being identical or the same are very close to being the same size and are within normal manufacturing tolerances, but seldom are precisely identical. A central through-bore  40  having a diameter Y is formed through the axial center of blind counter bore  36  such that the center of through-bore  40  is axially aligned with the axial center of bore  34 . The diameter Y is less than the diameter X to thereby define a seat  41  around through-bore  40  and created by the counter bore  36 . The term through-bore as used herein refers to a bore that penetrates entirely through the pertinent material in which the bore is formed. 
         [0018]    A pivot shaft bore  42  having a diameter Y (or nominally slightly larger than Y) is formed through tang end  18  of blade  12 . Because there are two handle halves  14  and  16 , a second pivot shaft bore  43  is formed through tang end  18  for receiving the other pivot axis associated with handle half  16 . The diameter of pivot shaft bore  43  also is Y. 
         [0019]    The pivot axis  20  is defined by a pivot shaft  44 , and pair of cartridge bearings  46  and  48  and a retainer nut  64 . Each of the cartridge bearings  46  and  48  is identical and are cartridge type bearings in which plural balls  50  are retained between inner and outer races. The bearings  46  and  48  are commercially available on the market. The outer diameter of each cartridge bearing  46 ,  48  is X (or nominally slightly smaller than X) so that a bearing, in the case of  FIG. 3 , cartridge bearing  46  may be inserted through bore  34  of side  32  in the direction of arrow A in  FIG. 3 , and seated in the seat  41  in side  30 , which as detailed above is formed by counter bore  36 . The thickness of cartridge bearing  46  is such that when the bearing is seated in seat  41  the exposed balls  50  are positioned such that when tang  18  of blade  12  is inserted into the tang slot  28  the balls  50  make contact with the side surface of the tang  18  (there are  7  balls  50  spaced around the periphery of the bearings  46 ,  48  shown in  FIG. 3 —it will be understood that these specific bearings are exemplary only). With the bearing  46  seated in seat  41 , the opening  54  through the center of the bearing is axially aligned with the axial center of through-bore  40 . 
         [0020]    The next step in assembly of the pivot axis  20  is to slide the tang  18  of blade  12  into tang slot  28  between sides  30  and  32  until the pivot shaft bore  42  is axially aligned with the through-bore  40 . The second cartridge bearing  48  is then inserted into bore  34  in side  32  of handle half  14  in the direction of arrow A until the balls  50  of bearing  48  rest on the surface  19  of tang  18  of the blade and such that opening  54  is axially aligned with through-bore  40 . Pivot pin  44  is then inserted through the aligned bores and openings in the direction of arrow A—that is, in sequential order, the distal end  62  of pivot pin  44  is inserted through bore  34  in side  32  and through opening  54  in bearing  48 , through pivot shaft bore  42  in tang  18  of blade  12 , and through opening  54  in bearing  46  and through through-bore  40  in side  30 . Pivot pin  44  has a bearing-contacting surface or seat  45  that in the assembled knife  10  bears against the balls  50  of cartridge bearing  48 —this is best seen in the sectional view of  FIG. 4 . The proximate end  56  of pivot pin  44  defines a larger diameter flange  60  that is received in a seat  58  formed on the outer surface of side  32  and around bore  34 . The distal end  62  of the pivot pin  44  extends through the entire assembly and a retainer nut  64  is attached to the distal end  62 , for example, with a threaded attachment or other attachment that allowed for compression of the components of the pivot axis. Retainer nut  64  includes a cylindrical and inwardly-projecting boss  66  that fits into a cylindrical recess  52  in the outer side of side  30  (not visible in  FIG. 3  but see  FIG. 4 ). Boss  66  has a threaded bore formed therethrough that is adapted for receiving the threaded end of pivot pin  44 . As such, when retainer nut  64  is threaded onto pivot pin  44  as shown in  FIG. 4  the boss  66  the nut may be tightened to secure the assembly. 
         [0021]    The same process is repeated with the components of pivot axis  22 , which is identical to the pivot axis  20  just described except as noted below: 
         [0022]      FIG. 4  is a cross sectional view taken along the line  4 - 4  of  FIG. 2 . It will be appreciated that in the orientation of the components of pivot axis  20  are the inverse of the components of pivot axis  22 , although in practice these components may be oriented in the same manner if desired. 
         [0023]    When assembled as illustrated in  FIG. 4 , the tang  18  of blade  12  rides on and is supported by the exposed balls  50  of the bearings  46 ,  48  and rotation of the blade about the pivot axes  20 ,  22  is very smooth and easy. More specifically, the retainer nuts  64  are tightened to the pivot pins  44  such that the exposed balls  50  of the cartridge bearings  46  and  48  are compressed between the seats  41  (of the sides  30 ,  32  of the handle halves) and the seats  45  of the pivot pins  44 . The retainer nuts  64  draw the pivot pin toward the center of the structure creating a compressive pre-load on the bearings, blade and handles. 
         [0024]    The components of pivot axes  20  and  22  and the structural features that they are assembled with in the handle halves  12  and  14  allow bearings to be easily installed into a monolithic handle. 
         [0025]    In the embodiment of knife  10  shown in  FIGS. 1 through 4  the material that is used to define the handle defines one of the surfaces on which the balls  50  of bearings  46  make contact. More specifically, the balls  50  of cartridge bearing  46  make direct contact with the material of handle  14  at seat  41 , as best shown in  FIGS. 3 and 4 . In some instances, the material that is used to fabricate the handles  14  and  16  may not define adequate surfaces on which the balls make contact. For example, if the handle material is relatively soft the balls can wear on the seat more rapidly than desired, which could negatively affect performance of the blade over time. 
         [0026]    This wearing-in phenomena may be alleviated or eliminated in several ways. A first method is to deposit a relatively harder surface in seat  41  on which balls  50  rotate—for example, with a deposited coating or an insert such as a washer that defines a harder surface. Another solution is illustrated in  FIG. 5 , which is a cross sectional view of a knife  100  that is analogous to the view of knife  10  shown in  FIG. 4 , except illustrating an alternative in which pivot axes  20  and  22  are defined by an alternative structure to those shown in  FIG. 4 . More specifically still, in  FIG. 5  the pivot axes  20  and  22  are defined by a three component pieces whereas the pivot axes  20  and  22  shown in  FIG. 4  have two analogous components, namely, the pivot pin  44  and the retainer nut  64 . 
         [0027]    In  FIG. 5  the bores  34  and  36  through the sides  30  and  32 , respectively, are both through-bores that have a diameter X. A retainer nut  70  threads onto the distal end  72  of pivot pin  74  and the inner-facing surface of nut  70  defines a bearing surface that bears against balls  50  of cartridge bearing  48  on the outer side of the bearing and defines the outer seat for the bearing (the surface  19  of tang  18  continues to define the seat against which balls  50  bear on the opposite side of the bearing). The pivot pin  74  includes a radial flange  78  that has an outer diameter X and which is received in bore  34  and the inner-facing surface  80  of which bears against balls of cartridge bearing  46 . The surface  19  of tang  18  defines the bearing surface against which balls  50  of cartridge bearing  46  ride on the opposite side thereof. A second retainer nut  82  threads onto the threaded end  84  of pivot pin  74  and the second nut  82  bears against the radial flange  78 . The knife lOs shown in  FIG. 5  is assembled in a manner similar to the assembly of knife  10  described above except that the second retainer nut  82  is used to adjust the tightness of the components of the pivots  20  and  22 . 
         [0028]    While the present invention has been described in terms of a preferred embodiment, it will be appreciated by one of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.