Abstract
A knife includes interchangeable blades that are secured within the handle using a locking mechanism having a lock pin disposed between the distal end of the lock bar and the blade. In addition to strengthening the lock, the lock pin also serves as a safety catch n the unlikely event of lock failure, resisting rotation of the blade into a position in which the user's fingers would be cut.
Claims
1. A knife, comprising: a blade having a shank, the shank having a proximal end defining a convex curved edge surface, the shank having a first shank side and a second shank side, with a locking projection extending upward from the first shank side, the blade further having a blade back surface extending upward from the shank; the blade further defining a support surface adjacent to the second shank side; a handle having a pair of handle sides, the handle defining a shank-receiving recess between the handle sides, the handle further having a blade support pin extending between the handle sides and corresponding to the support surface adjacent to the second shank side; a lock bar pivotally secured between the handle sides, the lock bar having a downwardly extending hook, the hook including a bottom surface, a first side surface extending upwardly from the bottom surface, and a second side surface extending upwardly from the bottom surface, the lock bar being movable between a locked position wherein the first side surface of the hook abuts the locking projection of the shank, and an unlocked position wherein the first side surface of the hook is disengaged from the locking projection of the shank, the lock bar being spring-biased towards the locked position; a lock pin extending between the handle sides adjacent to the shank-receiving recess, the lock pin being disposed between and abutting the second side surface of the hook and the blade back surface when the shank is within the shank-receiving recess and the lock bar is in the locked position, the lock pin being dimensioned and configured so that upon rotation of the blade about the blade support pin to an angular position that is downward from an angular position in which the blade is retained by the lock bar, the locking projection will abut the lock pin, resisting further rotation of the blade.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a side elevational view of a knife, with one handle panel removed.
(2) FIG. 2 is a side elevational view of a blade for the knife of FIG. 1.
(3) FIG. 3 is a side elevational view of a lock bar for the knife of FIG. 1.
(4) FIG. 4 is a perspective view of a first handle side panel for the knife of FIG. 1.
(5) FIG. 5 is a perspective view of a first handle side panel for the knife of FIG. 1.
(6) FIG. 6 is a perspective view of a second handle side panel for the knife of FIG. 1.
(7) FIG. 7 is a perspective view of a second handle side panel for the knife of FIG. 1.
(8) FIG. 8 is a side elevational view of a first step of inserting a blade into the handle of a knife of FIG. 1.
(9) FIG. 9 is a side elevational view of a second step of inserting a blade into the handle of a knife of FIG. 1.
(10) FIG. 10 is a side elevational view of a knife of FIG. 1, showing how the blade is intercepted prior to contacting a user's fingers in the unlikely event of lock failure.
(11) Like reference characters denote like elements throughout the drawings.
DETAILED DESCRIPTION
(12) Referring to the drawings, a knife 10 is illustrated. As shown in FIG. 1, the knife 10 has a plurality of blades 12, with the reference character 12 referring to a blade in general, and 12A, 12B, etc. referring to specific blades. The knife 10 also includes a handle 14 having first and second panels 16, 18, respectively. In most of the Figures, the handle panel 18 is removed for clarity. A lock bar 20 is pivotally secured between the handle panels 16, 18, and is spring-biased towards a locked position by a leaf spring 22 as described in greater detail herein.
(13) Referring to FIGS. 1-2, the blade 12A, 12B includes a body 24 having a cutting edge 26, a spine 28, and a tip or point 30 (not all blade tips will include points). Other blade styles that omit, modify, or substitute some features, for example, sheep's foot blades, gut hooks, plain edge and serrated edge blades, hawk bill blades, and the like, may all be used without departing from the invention. The common feature of all of the blade 12 is the shank 32. The shank 32, disposed opposite the tip or point 30, includes a convex curved edge surface 34 at its proximal end, providing the shank 32 with a tapered profile. The portion of the shank 32 corresponding to the spine 28 includes a locking projection or hook 36, with a lock bar receiving recess 38 defined between the hook 36 and the body 24. The lock receiving recess 38 includes a bottom surface 40, an upwardly extending surface 42 corresponding to the hook 34, and an upwardly extending blade back surface 44, corresponding to the body 24. The upwardly extending surface 44 includes a recess 46 for receiving a lock pin that will be described in greater detail below. The angle A3, formed between the surfaces 40, 42, is equal to or slightly less than 90° in the illustrated example. The side of the shank 32 corresponding to the edge 26 defines a support surface, which in the illustrated example is a support pin receiving recess 48, for abutting a blade support pin that will be described in greater detail below.
(14) Referring to FIGS. 1 and 3, the lock bar 20 is illustrated. The lock bar 20 includes a distal end 21 and a proximal end 23. A pivot hole 25 is located between the distal end 21 and proximal and 23, and in the illustrated example is centrally located on the lock bar 20. In some examples, the pivot hole 25 may be elongated as illustrated in FIG. 7 of U.S. Pat. No. 7,469,476. Other examples of the pivot hole 25 may be slightly larger than the pivot pin 60. The proximal end 23 of the lock bar 20 includes a spring support surface 27 and a spring stop surface 29, which in the illustrated example is substantially perpendicular to the spring support surface 27. The distal end 21 includes a downwardly projecting hook 31 defined by a lower surface 33 and a pair of upwardly projecting surfaces 35, 37 on either side of the hook 31. The surface 35 in the illustrated example includes a slight convex curvature. In the illustrated example, the angle A1 is slightly greater than 90°, and the angle A2 is slightly less or equal to 90°. The angles A2, A3 are selected so that the surfaces 37, 42 are substantially parallel when the blade 12 is locked in position as described below.
(15) The first panel 16 of the handle 14 is illustrated in FIGS. 1 and 4-5. The panel 16 includes a distal end 40 and the proximal end 42. The back edge 44 and front edge 46 extends between the distal end 40 and proximal end 42. The front edge 46 in the illustrated example includes a finger groove 48 for receiving the index finger of the user, thus securing the knife 10 within the user's grip. The back edge 44 includes a recess 50 to facilitate depression of the lock bar 20. The front edge 46 also includes a female interlocking projection 52, which in the illustrated example defines a pair of slots 54, 56. A pivot pin hole 58 is defined centrally, and proximate to the back edge 44, for receiving the pivot pin 60 for the lock bar 20. Some examples of the pivot pin hole 58 may have a larger diameter than the pivot pin 60, or may be elongated in a direction extending between the distal and proximal ends of the panel 16. A hole 62 is defined in the distal end 40, proximate to the rear edge 44, for receiving the lock pin 64. The illustrated example of the hole 62 is counterbored, including a larger diameter portion 66 on the inner side 68, and a smaller diameter portion 70 on the outer side 72. A support pin aperture 74 is also defined within the distal end 40, proximate to the front edge 46. The support pin aperture 74, for receiving the support pin 76, also includes a larger diameter portion 78 adjacent to the inside surface 68, and a smaller diameter portion 80 adjacent to the outer surface 72. The interlocking projection 52 extends around the distal end 42 of the panel 16, defining apertures 82, 84 as well as slot 86 for receiving corresponding projections on the handle 18 are described below. The interlocking projection 52 also defines a channel 88 for receiving the leaf spring 22 therein. In the illustrated example, a lanyard hole 90 extends through the proximal end 42.
(16) The second handle panel 18 is illustrated in FIGS. 6-7. The second handle panel 18 is in some respects a mirror image of the first handle panel 16. The second handle panel 18 includes a distal end 92 and proximal end 94, corresponding to the distal end 40 and proximal end 42 of the first panel 16. The panel 18 further includes a back edge 96 and front edge 98 corresponding to the back edge 44 and front edge 46 of the panel 16. The front edge 98 includes a finger groove 100 corresponding to the finger groove 48, and the back edge 96 includes a recess 102 corresponding to the recess 50 of the panel 16. A lock pivot hole 104 is defined centrally on the panel 18, adjacent to the back edge 96, so that when the panel 16, 18 are joined together, the holes 58, 104 will be substantially coaxial. Some examples of the pivot pin hole 104 may have a larger diameter than the pivot pin 60, or may be elongated in a direction extending between the distal and proximal ends of the panel 18. Similarly, the support pin hole 106 is substantially coaxial with the whole 62, and also includes a larger portion 108 corresponding to the inner surface 110 of the panel 18, and a smaller diameter portion 112 corresponding to the outer surface 114 of the panel 18. Similarly, the blade support pinhole 116 is positioned to be substantially coaxial with the whole 74 of the panel 16. The support pinhole 116 also includes a large diameter portion 118 corresponding to the inner surface 112, and a smaller diameter portion 120 corresponding to the outer surface 114. The inner surface 110 also includes projection 122 that is dimensioned and configured to fit within the slot 56. Similarly, the projection 124 is dimensioned and configured to fit within a slot 54. Projections 126, 128 are dimensioned and configured to fit within the holes 84, 82, respectively. Projection 130 is dimensioned and configured to fit within a slot 86. In the illustrated example a lanyard hole 132 is positioned to be substantially coaxial with the hole 90.
(17) Referring back to FIG. 1, the handle 14 is assembled by placing the lock pivot pin 60 within the aperture 58 of the panel 16. The lock pin 64 is placed within the aperture 62. The blade support pin 76 is placed within the apertures 74 of the panel 16. The lock bar 20 is positioned so that the pin 60 passes through the aperture 25, and so that the hook 31 corresponds to the distal end 40 of the panel 16. The spring 22 is positioned with one and 134 within the slot 88, and the opposite end 136 abutting the intersection between the spring support surface 27 and spring stop 29. The panel 18 is then joined to this assembly, with the lock pin 64 passing into the aperture 106, the blade support pin 76 passing into the aperture 116, and the lock pivot pin 60 passing into the aperture 104. The projections 122, 124, 126, 128, and 130 are simultaneously inserted into the slots 56, 54, holes 84, 82, and slot 86, respectively. At this point, the handle 14 is ready to removably secure any desired blade 12 within the recess within the distal end of the handle in the manner described below.
(18) Although the panel 18 will typically be in place during installation and removal of the blade 12, panel 18 has been removed from FIGS. 8 and 9 for clarity. As shown in FIG. 8, the shank 32 of any desired blade 12 can be inserted between the distal ends 40, 92 of the panel 16, 18, respectively. As shown in FIG. 9, the convex curved surface 34 and resulting tapered profile will direct the shank 32 upward, with the same curved surface 34 pushing the hook 31 of the lock bar 20 upward to permit passage of the shank 32 completely into the handle 14, until it reaches the position illustrated in FIG. 1. In this position, with the hook 36 completely past the hook 31, the hook 31 is biased into the recess 38, with the surface 37 of the lock bar 20 abutting the surface 42 of the blade 12, and the surface 35 of the lock bar 20 abutting the lock pin 64. The blade support pin 76 is within the recess 48 on the blade 12, providing support for the side of the blade 12 having the edge 26. The lock pin 64 is within the recess 64, supporting the side of the blade adjacent to the spine 28. Depressing the proximal end 23 of the lock bar 20 disengages the hook 31 from the hook 36, permitting removal of the blade 12 from the handle 14.
(19) The lock pin 64 provides two different advantages to the knife 10: strengthening the lock, and providing a safety catch in the very unlikely event of lock failure. With the hook 31 wedged between the hook 36 and lock pin 64, pressure on the cutting edge 26 of the blade 12 is resisted by the lock pin 64 rather than the pivot pin 60. Similarly, pressure on the spine 28 of the blade 12 causes the hook 36 to push the hook 31 into the lock pin 64, so that this force is also resisted by the lock pin 64 rather than the pivot pin 60. Given the distance between the blade 12 and pivot pin 60, any forces applied at an angle could potentially create leverage that would increase the amount of force applied to the pin 60. Resisting these forces closer to the blade 12 with the pin 64 minimizes the likelihood of such force-multiplying leverage exceeding the strength of a pin. Additionally, when the hook 31 is wedged between the hook 36 and pin 64, the surface 33 of the lock bar 20 will ordinarily not be in contact with the surface 40 of the blade. The angles of the surfaces 35, 37 of the lock bar 10 are such that the hook 31 tapers to a narrower width as the surface 33 is approached. As the knife 10 is used repeatedly and the various components are subject to wear, the hook 31 may pass farther into the recess 38 to compensate for wear.
(20) The second advantage is best illustrated in FIG. 10. In the very unlikely event of lock failure, the blade 12 will rotate around the blade support pin 76 until the hook 36 abuts the lock pin 64. Pin 64 thereby resists additional rotation of the cutting edge 26 towards the fingers of the user. Pin 64 thus functions not only as a lock strengthening pin, but also as a safety catch.
(21) The present invention therefore provides a fixed blade knife having interchangeable blades. The knife includes a particularly strong blade retention mechanism. The knife also includes a safety catch that resists rotation of the blade to a position in which the user's fingers would be injured in the unlikely event of lock failure.
(22) A variety of modifications to the above-described embodiments will be apparent to those skilled in the art from this disclosure. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention. The appended claims, rather than to the foregoing specification, should be referenced to indicate the scope of the invention.
