Abstract:
An improvement for a dual handle fighting knife having interlocking handles when in open position and multiple spring blades stabilization in open and closed position. The handle blade spring engagement provides for a safe, straight-forward interlocking blade position and spacing of said cutting edge engagement with said handle when in closed position.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   This invention relates to knives, specifically folding knives that have a blade attached to a pivoting handle. Such knives typically lock in open use or closed position with the blade stored within or partially within the handle. 
   2. Description of Prior Art 
   A dual handle knife or “butterfly, fighting” knife typically has a pair of pivoting handles, each of which covers one-half the blade in folded closed position and forms a full hand grip in open use position. 
   A number of prior dual handle “butterfly” type knives have been developed with modified blade and handle locking mechanisms. Such locking systems have relied on a variety of additional engagement structures as seen generally in U.S. Pat. Nos. 4,047,298, 4,364,174, 4,547,965, 6,195,898 and 6,848,183. 
   In U.S. Pat. No. 4,047,298 a sheath and rigid handle for a knife is disclosed in which a two-piece full handle pivots at right angles to the blade. 
   U.S. Pat. No. 4,364,174 claims an improved manufacturing method for a handle of a butterfly fighting knife. 
   A synchronized folding knife is seen in U.S. Pat. No. 4,547,965 having a pair of channel handles that are pivotally connected to a knife blade with mesh gears. 
   U.S. Pat. No. 6,195,898 is directed to a magnetically locking butterfly fighting knife having a pair of magnets on the respective end handle portions so as to be magnetically attracted to one another in either open or in closed position due to the corresponding positioning of the plurality of the magnets. 
   Finally, in U.S. Pat. No. 6,848,183 a thumb lock for a butterfly fighting knife is disclosed wherein a locking mechanism is positioned on the distal end of the knife handles and has a movable magnetic components and interengaging swing elements associated therewith. 
   SUMMARY OF THE INVENTION 
   A locking dual handle “butterfly type fighting knife” having a pair of integral blade engaging elongated spring urged handle elements that selectively engage a compound configured surface of pivoted handle engagement points. Such multiple selective sequential registration provides for positive multiple handle positions that are sequentially engaged from a locked closed position to intermediate and then to an open use locked positions. Handle interengagement portions prevent translateral movement of the handle elements with one another when in open use position. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevational view of the knife of the invention in open use position. 
       FIG. 2  is a partial enlarged side elevational view of the improved handle and blade configurations of the invention in open use locked position. 
       FIG. 3  is a side elevational view of the knife as seen in closed locked position. 
       FIG. 4  is an enlarged side elevational view with portions broken away illustrating intermediate handle positions. 
       FIG. 5  is an enlarged side elevational view with portions broken away in open use position illustrating blade shank pivot surface engagement with respective handle portions. 
       FIG. 6  is a side elevational view of the blade handle spring elements in open independent position. 
       FIG. 7  is a side elevational view of the blade handle spring elements in closed independent position orientation. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1-4  of the drawings, a folding knife  10  of the invention can be seen having a blade portion  11  and a handle portion  12 . The blade portion  11  has a blade element  13  with an end point  14 , back edge  15  and oppositely disposed cutting edge  16 . A shank  17  of the blade has bifurcated handle engagement shank portions  18 A and  18 B with respective pivot apertures  19 A and  19 B therewithin, 
   Each of the shank portions  18 A and  18 B have different angled engagement surfaces  20  with the shank portion  18 B having a tapered outside edge  21  with a right angular end edge  22 . An angularly disposed return edge  23  terminates at a joining end edge  24  extending between the respective bifurcated end portions. The shank portion  18 A has an outside tapered edge  25  with a right angled end edge  26 . A corresponding return edge  27  has an angularly disposed surface effacing the hereinbefore described return edge  23  and terminates in the corresponding adjoining end edge  24 , as noted. 
   It is important to note that the return angled edge surfaces of the shank portions  18 A and  18 B are at a precise angular inward inclination away from one another indicated for engagement with the handle portion  12  as will be described in greater detail hereinafter. 
   The handle portion  12  is comprised of a pair of independent handle elements  28  and  29 , best seen in  FIGS. 1 ,  2  and  3  of the drawings which are pivotally secured to the respective shank portions  18 A and  18 B by pivot pins  30 A and  30 B respectively. 
   Each of the handle elements  28  and  29  have elongated compound shaped spring plates  31  and  32  respectively, best seen in dotted lines and independently in solid lines in  FIGS. 6 and 7  of the drawings. The spring plates  31  and  32  have engagement end portions  33  and  34  and are secured to the respective handle elements  28  and  29  by multiple fasteners F positioned along their longitudinal length. 
   In operation, as shown in open “used” blade extended and locked position as seen in  FIGS. 1 ,  2 ,  5  and  6  of the drawings, the spring plate end engagement portions  33  and  34  are registerable on the respective effacing shank portion&#39;s angled surfaces  23  and  27  and the handle element pairs  28  and  29  are engaged with one another for use. A spring plate portion  35  interlocks the free ends of the handle portions  28  and  29  as best seen in  FIG. 2  of the drawings preventing handle translateral movement therebetween. 
   The respective engagement surfaces of the end engagement portions  33  and  34  impart a co-lateral force on the incline return surfaces  23  and  27  of the shank portions  18 A and  18 B due to their angular inclination thus maintaining a secure lock position in the open configuration. 
   Referring to  FIG. 4  of the drawings, it will be seen that the handle portions  28  and  29  have been closed midway in which the spring plate end engagement portions  33  and  34  fully engage the respective shank portion end surfaces  22  and  26  imparting a positive positioning thereto at right angles to the blade. 
   Upon closure, as seen in  FIG. 3  of the drawings, the handle portions  28  and  29  are respectively engaged over the back of the blade edge  15  and cutting edge  16  of the blade  13 . In this position the spring end plate portions  33  and  34  are now in contact with the corresponding outer surfaces  21  and  25  of the shank portions  18 A and  18 B which due to their angular inclination as previously described will force the handles  28  and  29  together, holding the handles tightly closed on the blade  13  as described. The spring plate  32  has an extending blade stop  40  inwardly of its end engagement portion  34  that prevents the blade  13  upon full closure of the handle  29  thereon from engagement with the cutting edge  16  by spaced contact therewith indicated generally at  41 . 
   Correspondingly, the handle portion  28  is held tightly against the back edge  15  of the blade  13  with the spring plate  31  resting along the back edge  15  of the blade as best seen in  FIG. 3  of the drawings in dotted lines. 
   If will be evident from the above description that the improved dual handle fighting knife  10  of the invention provides for a unique multiple handle retainment positionings wherein the spring plates  31  and  32  engagement configuration with the angular orientation of the shank portions  18 A and  18 B corresponding registration surface pairs  23  and  27  when in open position and  21  and  25  when in closed position and  22  and  23  when in transition position. The handle pairs  28  and  29  and blade  13  will always be in retained resistant relation to one another that is novel only to a dual handle folding knife  10  of the invention with the above described critical improvements and structural configurations as defined.