Abstract:
A folding knife includes a lock blade and a handle. The handle includes a transfer bar assembly and a blade opener spring. When the lock blade is closed, a spring working in conjunction with the transfer bar assembly biases the lock blade closed. When the lock blade is opened past a certain point, a blade opening spring assists in moving the lock blade into its open locked position.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of folding knives, and more particularly to a folding knife with a spring driven opening mechanism. 
       BACKGROUND OF THE INVENTION 
       [0002]    Folding knives are popular due to their compact size and portability. However, a potential drawback of certain folding knives is that they require two hands for use. One hand is required for holding the handle portion of the blade, while the other hand is necessary to withdraw the blade from its retracted position within the handle and move the blade to the extended, operable position. 
         [0003]    In most assisted-opening folding knives, a leaf torsion spring or straight wire spring is used, so that when the knife is opened, the spring provides an initial assist to move the blade, but the continued opening of the blade relies on inertia to complete the opening process. 
         [0004]    For example, the folding knife disclosed in U.S. Pat. No. 5,815,927 (Collins) allows the user to extract the blade from its refracted position within the handle by the user&#39;s engaging and pulling on ridges defined in a rear portion of the blade. A plunger mechanism having a coil spring facilitates opening of the blade, but the user is still required to pull on the ridges in order to move the blade through a selected range of motion and for the spring to assist the blade to move it to the extended position. 
         [0005]    Many folding knives have been patented. U.S. Pat. No. 273,858 (Korn) discloses a folding knife having a leaf-type spring for moving a blade to an extended position. U.S. Pat. No. 1,603,914 (Hermann) discloses a folding knife having a coil spring connected to a metal tape, which pulls the blade to a retracted position. U.S. Pat. No. 2,601,999 (Sly) discloses a foldable gaff hook having a similar opening mechanism. U.S. Pat. No. 2,407,897 (Newman) discloses a spring for pivoting blade open upon actuation of a locking lever. U.S. Pat. No. 698,080 (Treas) discloses use of an actuating spring for pivoting a blade to an open position. U.S. Pat. No. 4,535,539 (Friedman, et al.) and U.S. Pat. No. 5,093,995 (Jan) disclose button release mechanisms for folding knives. U.S. Pat. No. 4,893,409 (Poehlmann) and U.S. Pat. No. 5,964,035 (Poehlmann) disclose folding knives having adjustment screws for adjusting the fit of the blade in the extended position. U.S. Pat. No. 1,065,863 (Carter) also discloses use of set, or an adjustment, screw. U.S. Pat. No. 6,397,477 (Collins) discloses a spring-assisted folding knife which initiates pivoting a blade from a retracted position to a locked extended position. These knives typically use either inertia, gravity-assist, or a flick of the wrist to complete the opening process. 
       SUMMARY OF THE INVENTION 
       [0006]    Briefly stated, a folding knife includes a lock blade and a handle. The handle includes a transfer bar assembly and a blade opener spring. When the lock blade is closed, a spring working in conjunction with the transfer bar assembly biases the lock blade closed. When the lock blade is opened past a certain point, a blade opening spring assists in moving the lock blade into its open locked position. 
         [0007]    According to an embodiment of the invention, a folding knife includes a lock blade; and a handle connected to the lock blade; wherein the handle includes a transfer bar assembly biased by a compression spring; and a blade opener spring connected to the lock blade; such that when the lock blade is in a closed position, the transfer bar assembly biases the lock blade into the closed position, and such that when the lock blade is opened past a certain point, the blade opener spring assists in moving the lock blade into an open position. 
         [0008]    According to an embodiment of the invention, a method of manufacturing a folding knife includes the steps of making a file side handle, a lock side liner, a spline, a mark side liner, a mark side handle, and a lock blade; wherein the lock side liner, the spline, and the mark side liner each contain a transfer bar assembly recess; making a transfer bar assembly by (a) making a front transfer bar, (b) making a rear transfer bar, (c) making a leaf spring, (d) pivotally connecting the front transfer bar to the rear transfer bar, and (e) connecting the leaf spring to the rear transfer bar such that the leaf spring biases the front transfer bar so that the front transfer bar is axially aligned with the rear transfer bar; making a compression spring and a blade opener spring; and assembling the folding knife. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows an exploded perspective view of a folding knife according to an embodiment of the invention. 
           [0010]      FIG. 2  shows a perspective view of a lock blade according to an embodiment of the invention. 
           [0011]      FIG. 3  shows a front elevation view of a spine according to an embodiment of the invention. 
           [0012]      FIG. 4A  shows a perspective view of a front transfer bar according to an embodiment of the invention. 
           [0013]      FIG. 4B  shows a top view of a leaf spring according to an embodiment of the invention. 
           [0014]      FIG. 4C  shows a perspective view of a rear transfer bar according to an embodiment of the invention. 
           [0015]      FIG. 4D  shows a perspective exploded view of the front transfer bar, rear transfer bar, and leaf spring according to an embodiment of the invention. 
           [0016]      FIG. 4E  shows a perspective view of a transfer bar assembly according to an embodiment of the invention. 
           [0017]      FIG. 5  shows a front elevation view of a mark side liner according to an embodiment of the invention. 
           [0018]      FIG. 6  shows a perspective view of a liner lock according to an embodiment of the invention. 
           [0019]      FIG. 7A  shows a front elevation view, including stippling, of a file side handle according to an embodiment of the invention. 
           [0020]      FIG. 7B  shows a perspective view of the file side handle of  FIG. 7A . 
           [0021]      FIG. 8A  shows a front elevation view, including stippling, of a mark side handle according to an embodiment of the invention. 
           [0022]      FIG. 8B  shows a perspective view of the mark side handle of  FIG. 8A . 
           [0023]      FIG. 9A  shows a front elevation view of a blade opener spring according to an embodiment of the invention. 
           [0024]      FIG. 9B  shows a top view of the blade opener spring of  FIG. 9A . 
           [0025]      FIG. 9C  shows a perspective view of the blade opener spring of  FIGS. 9A-9B . 
           [0026]      FIG. 10  shows a method of assembly of the folding knife of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    Referring to  FIG. 1 , a folding knife  10  is shown in its component parts. Referring also to  FIG. 2 , a lock blade  20 , preferably made of 420HC stainless and preferably heat treated to 50-59 HRC, includes an edge  24 , a blade spine  26  with a notched area  28  on it, and a tang  22 . Blade spine  26  preferably includes a recessed area  32  with a threaded hole  34  centered therein which receives a thumb stud screw  38  which attaches a thumb stud  36  to lock blade  20 . Tang  22  includes a hole  30  and a hole  150  which are used in the knife assembly process, a sear  40 , and a cutout area  42 . Cutout area  42  ensures that lock blade  20  doesn&#39;t interfere with the remainder of the knife as it is folded. The purpose of sear  40  will be explained later. 
         [0028]    Referring now to  FIGS. 1 and 3 , a spine  50  is preferably of 420 stainless and includes a transfer bar assembly recess  52  for receiving a transfer bar assembly  70 , a recess  54 , a liner lock stop  56 , a plurality of threaded holes  58 , and a lanyard hole  60 . 
         [0029]    Referring to  FIGS. 1 and 4 , transfer bar assembly  70  includes a front transfer bar  72  which includes a hook  84 , while a rear transfer bar  74  includes a bar  82 . Hook  84  fits over bar  82 , thus connecting front transfer bar  72  to rear transfer bar  74  while allowing front transfer bar  72  to pivot with respect to rear transfer bar  74 . A leaf spring  76  is connected across front transfer bar  72  and rear transfer bar  74  to keep transfer bar assembly  70  biased in the straight position. Leaf spring  76  is preferably made of stainless steel, while front transfer bar  72  is preferably made of high carbon stainless steel, so leaf spring  76  can be welded to front transfer bar  72 . Rear transfer bar  74  is preferably made of a plastic such as DELRIN®, so a stud hole  78  is formed near an end of leaf spring  76  which fits over a stud  80  on rear transfer bar  74 . Leaf spring  76  is then connected to rear transfer bar  74  preferably by hot melting stud  80 . 
         [0030]    Referring to  FIGS. 1 and 5 , a mark side liner  90  includes a curved slot  92  and a transfer bar assembly recess  94 . Mark side liner also includes a hole  96 , a plurality of threaded holes  98 , and a lanyard hole  99 . 
         [0031]    Referring to  FIGS. 1 and 6 , a lock side liner  100  includes a transfer bar assembly recess  107  and a liner lock  102 . Lock side liner  100  also includes a hole  106 , a plurality of threaded holes  108 , and a lanyard hole  109 . 
         [0032]    Referring to  FIGS. 1 and 7 , a file side handle  110  includes a hole  112 , a plurality of threaded holes  114 , and a lanyard notch  116 . 
         [0033]    Referring to  FIGS. 1 and 8 , a mark side handle  130  includes a hole  134 , a plurality of threaded holes  136 , a lanyard notch  138 , and a belt clip recess  132 . 
         [0034]    Referring to  FIGS. 1 and 9 , a blade opener spring  142  is shown, with an end  144  bent orthogonally to a plane running through a circumference of a circular portion of spring  142 , and another end  146  bent outward along a radial axis of the circular portion of spring  142 . Blade opener spring  142  is a torsion coiled spring, preferably of 0.025 inch diameter music wire. 
         [0035]    Referring to  FIGS. 1 and 10 , folding knife  10  is preferably assembled as follows. In step  201 , transfer bar assembly  70  is completed by fitting front transfer bar  72  to rear transfer bar  74  by placing hook  84  over bar  82 . Leaf spring  76  is placed onto stud  80  of rear transfer bar  74  ( FIG. 4 ) a attached by hot melting stud  80  or riveting. In step  202 , file side handle  110  is preferably placed in an assembly fixture (not shown) or held in a person&#39;s hand (not shown), after which lock side liner  100  is placed onto file side handle  110 , followed by blade washer  44   a  and spine  50 . If using the assembly fixture, the assembly fixture contains a blade assembly guide pin which fits through holes  112 ,  106 , and blade washer  44   a.  If using one&#39;s hand, male blade screw  118  preferably forms this function. 
         [0036]    In step  203 , a compression spring  148  is inserted into transfer bar assembly recess  52  of spine  50 , and in step  204 , transfer bar assembly  70  is inserted in the front portion of spine  50  in front of compression spring  148 . Compression spring  148  is thus to the rear of transfer bar assembly  70 . “Rear” denotes the end of spine  50  which contains lanyard hole  60 , while “front” denotes the opposite end. 
         [0037]    In step  205 , hole  30  of lock blade  20  is placed onto the blade assembly guide pin if using the assembly fixture, or alternatively onto the end of male blade screw  118 . Folding knife  10  is preferably assembled with lock blade  20  in the open position. In step  206 , blade washer  44   b  is placed onto the blade assembly guide pin if using the assembly fixture, or alternatively onto the end of male blade screw  118 . 
         [0038]    In step  207 , mark side liner  90  is emplaced onto the growing knife assembly. Then, in step  208 , a blade opener spring  142  is placed onto the blade assembly guide pin if using the assembly fixture, or alternatively onto the end of male blade screw  118 . End  144  must be placed through curved slot  92  into hole  150  of lock blade  20 . In step  209 , mark side handle  130  is placed onto mark side liner  90 . 
         [0039]    In step  210 , body screws  122  are screwed into corresponding holes  136  on mark side handle  130 . In step  211 , the finished knife assembly is removed from the assembly fixture if one is being used. In step  212 , belt clip  140  is placed into belt clip recess  132 , after which female blade screw  120  is inserted into hole  134  in step  213 . If the assembly fixture was used to assemble the knife, in step  214  male blade screw  118  is inserted into hole  112  and screwed into the end of female blade screw  120 ; but if no assembly fixture was used and male blade screw  118  is already within the knife assembly, at this step male blade screw  118  is simply screwed into female blade screw  120 . 
         [0040]    In step  215 , body screws  122  are screwed into corresponding holes  114  in file side handle  110 . Finally, in step  216 , thumb stud  36  is fastened in place in recess area  32  using thumb stud screw  38 . 
         [0041]    Folding knife  10  is an assisted opening folding knife. When lock blade  20  is in the closed position, it is biased into the closed position by compression spring  148 , with sear  40  engaging transfer bar assembly  70 . When opening lock blade  20 , once lock blade  20  is moved out approximately  30 ° and front transfer bar  72  clears sear  40 , the action of blade opener spring  142  moves lock blade  20  into the fully open position. 
         [0042]    While the present invention has been described with reference to a particular preferred embodiment and the accompanying drawings, it will be understood by those skilled in the art that the invention is not limited to the preferred embodiment and that various modifications and the like could be made thereto without departing from the scope of the invention as defined in the following claims.