Abstract:
An improved apparatus for sharpening the cutting edge of a knife blade or other cutting implement including a frame assembly having clamping means for securing the blade thereto and guide means for maintaining an abrading means or an abrading assembly in a substantially constant angular relationship with the blade. The apparatus also includes means for accommodating a variety of blade sizes and thicknesses as well as means for performing abrading operations varying from coarse to fine on the blade without changing or rotating the abrading assembly. Handle means are also provided and include shield means for protecting the hands of the user.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates generally to an apparatus for sharpening knife blades or other cutting implements, and more particularly to such an apparatus which is manually operable and has an abrading assembly that is slidably movable in engagement along the knife blade or other cutting implement for abradingly forming a sharpened cutting edge portion thereon. 
     Various devices have been provided for forming a sharpened cutting edge portion on a knife blade or other cutting implement and are available in a wide variety of types and configurations. Many of such devices are powered by electric current and thus suffer the disadvantage of being unusable in remote areas where electric power is not available. Other prior sharpening devices are manually operated, but are frequently expensive and relatively cumbersome to use. 
     With regard to other prior sharpening devices that are portable and lightweight, it is known to use a pair of separate gripping fingers to clamp a knife blade to be sharpened, with the fingers being clamped together via a fastener assembly. In the present invention, however, the fingers are pivotally hinged together to facilitate handling. In addition a resilient member urges and holds the two gripping fingers apart to assist in the insertion of the blade between the fingers. The fingers are also provided with confronting ridges, which define a stop, and locating surfaces which assist in aligning the blade to be sharpened. 
     In the present invention, the gripping fingers are part of a frame assembly. A separate abrading means (which includes abrading members on a support rod) is pivotally and slidably engageable with guide means on the frame assembly for guiding and maintaining the abrading means in a substantially constant angular relationship with the cutting edge as the abrading means is moved along the cutting edge. Preferably, the sharpening apparatus of the present invention includes means for altering or adjusting the angular relationship between the abrading means and the cutting edge in order to accommodate cutting implements of various sizes or configurations while still maintaining a substantially constant angular relationship between the abrading means and the cutting implement during sharpening. The preferred abrading means comprises an abrading assembly having a number of axially aligned abrading members on a single rod, each of which has a different grit or coarseness in order to allow the user to initially perform relatively coarse abrading operations on the cutting edge portion of the cutting implement and to finish the sharpening operation with a relatively fine abrading member, thereby achieving a smooth, sharp cutting edge. Since the abrading members are axially aligned on a single rod the sharpening operation can be completed without the need to use a plurality of abrading means and with a minimum amount of manipulation of the support rod. 
     Since the apparatus is operated manually, one of the objectives of the present invention is to provide such a shield-like structure wherein the user&#39;s hands are substantially protected from the cutting edge being sharpened. As will be seen, by locating the abrading members in axial alignment, the shield can be made substantially wide to enhance protection of the operator&#39;s hand. 
     The preceding are some of the features of the present invention. Additional objects, advantages, and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an apparatus for sharpening a cutting implement according to the present invention. 
     FIG. 2 is a top view of the sharpening apparatus of FIG. 1. 
     FIG. 3 is an end view, partially broken away in cross-section, of the sharpening apparatus of FIG. 1, illustrating various positions of the abrading assembly engaged or interconnected with the guide means thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 through 3 of the drawings illustrate an exemplary preferred embodiment of an apparatus according to the present invention for sharpening a knife blade or other cutting implement. One skilled in the art will readily recognize from the drawings and the following discussion that the principles of the invention are equally applicable to a sharpening apparatus other than that shown for purposes of illustration in the drawings. 
     As illustrated in FIGS. 1 through 3, a sharpening apparatus 10 according to the present invention is illustrated in use for sharpening a knife blade 11 or other cutting implement in order to form a sharpened cutting edge portion 13. The sharpening apparatus 10 includes a frame assembly 12, preferably having a pair of clamping members 14a and 14b, which are pivotally interconnected by a hinge assembly 16. Clamping members 14a and 14b are provided with elongated clamping finger portions 17a and 17b, respectively, which are adapted to be pivoted toward and away from each other via the hinge assembly 16. The hinge assembly 16 is formed with an elongated socket portion 18 at the base of finger portion 17b of clamping member 14b and is adapted to be hingedly interconnected with a complementary elongated pivot pin protrusion 20 at the base of the finger portion 17a of the other clamping member 14a. As will become readily apparent from the following description, such a hinge assembly configuration allows the clamping members 14a and 14b  to be of a one-piece construction formed by conventional extrusion processes permitting the production of an inexpensive but high quality device. 
     The clamping members 14a and 14b are equipped with a threaded fastener assembly 24 including a threaded screw 26 extending through aligned openings in finger portions 17a and 17b, and threadably engaging a nut 27 for urging the finger portions 17a and 17b toward one another to clamp the blade 11 therebetween. 
     The clamping surfaces of the finger portion 17a and 17b include one or more stepped recessed portions 22a, 23a and 22b, 23b, respectively, for abuttingly engaging the backside of the blade 11. The recessed portions 22a, 22b and 23a, 23b define stop surfaces or shoulders for locating the blade and for aligning the blade relative to the sharpening apparatus 10. A resilient spring-type wavy washer 25, or other biasing means, is provided for biasing the finger portions 17a and 17b away from one another in order to facilitate easy and convenient insertion of the blade 11 into the space between them prior to actuation of the threaded fastener assembly 24 or other securing means. 
     The clamping members 14a and 14b also include guide members 28a and 28b, respectively, which are integral with the clamping members and which extend generally transversely and outwardly at acute angles in opposite directions from the bases of finger portions 17a and 17b, respectively. The guide members 28a and 28b include a plurality of elongated guide openings 30a, through 30c and 31a through 31c, respectively. The guide members 28a and 28b are adapted to be engaged by, or pivotally interconnected with, an abrading assembly 40 as described below. 
     The abrading assembly 40 generally includes a body portion 42 having one or more hone or abrading members 46a, 46b and 46c thereon. An elongated rod-like member 48 extends in a generally parallel or colinear direction from the body portion 42 and is adapted to be inserted into any of the preselected guide openings 30a through 30c, or 31a through 31c, on either of the guide members 28a or 28b in a pivotal engagement or interconnection therewith. By inserting the rod-like member 48 into a preselected guide opening 30a through 30c, or 31a through 31c, the abrading members 46 may be slidably engaged with the cutting edge portion 13 of the blade 11 and slidably moved back and forth along and/or across the blade in order to abradingly sharpen the cutting edge 13. As shown in FIG. 3, in phantom lines, the rod-like member 48 of the abrading assembly 40 may be inserted into the appropriate one of the guide openings to accommodate the size, height, and configuration of the blade 11 or other cutting implement being sharpened. Although the guide openings may have any of a number of suitable shapes, it is preferred that they are elongated as shown in the drawings in order to provide for a substantial amount of pivotal travel of the abrading assembly 40 back and forth along and/or across the cutting edge 13 during the abrading operation. 
     It should be noted that regardless of which of the elongated guide opening 30a through 30c, or 31a through 31c, on either of the guide members 28a or 28b, the angular relationship between the abrading members 46 and the blade 11 is maintained substantially constant during the slidable abrading movement of the abrading assembly 40 along and/or across the blade 11 for a given preselected guide opening. This allows for sharpening the cutting edge portion 13 on the blade 11 in a generally uniform manner. A plurality of abrading members 46a, 46b, and 46c, having different degrees of coarseness or grit are provided on the single abrading assembly 40 in order to allow the user to initially perform relatively coarse sharpening operations on the cutting edge 13 and progressively perform finer sharpening operations in order to form a smooth sharp cutting edge 13. Thus only one abrading assembly 40 is required to perform the complete sharpening operation. It should also be noted that the plurality of abrading members are disposed longitudinally in line, in a generally end-to-end relationship with one another, as shown in the drawings and preferably have their abrading (blade engaging) surfaces oriented generally in the same direction. Thus the abrading assembly 40 need only be moved longitudinally to permit use of the different abrading members 46a through 46c. 
     As illustrated in the drawings, the guide members 28a and 28b are formed at an appropriate angle with the respective finger portions 17a and 17c, and hence with the blade 11, such that the rod-like member 48 forms an approximately 90-degree angle with the guide members 28a and 28b when inserted into any of the guide openings 30a through 30c, or 31a through 31c when the abrading members 46a, 46b, or 46c abradingly engage the cutting edge 13. Such a relationship facilitates a generally smooth and unrestricted pivotal engagement between the rod-like member 48 and the selected guide opening 30a through 30c, or 31a through 31c. 
     The body portion 42 of the brading assembly 40 also includes an elongated rib on the opposite side thereof from the abrading members 46a through 46c, which defines a handle portion 50 being adapted to be gripped by the user of the sharpening apparatus 10. In order to protect the user&#39;s hands or other gripping means from injury or damage resulting from contact with the cutting edge 13, the body portion 42 includes one or more shield portions 52 disposed generally between the handle portion 50 and the abrading members 46a through 46c. It should be noted that the shield portions 52 extend for a substantial distance outwardly from the handle portion 50 in order to protect the user&#39;s fingers which are gripping the handle portion 50. In one form of the invention the shield portions 52 extend outwardly or laterally from the handle portion 50 a distance that is at least equal to the width of the abrading members 46a through 46c. It can also be seen that the shield portions 52 are formed at an angle with the handle portion 50 so as to be inclined rearwardly away from the abrading members 46a through 46c. This inhibits or minimizes the possibility of contact between the shield portions 52 with the cutting edge 13 during the sharpening operation. It also minimizes the possibility of contact between the operator&#39;s hands and the cutting edge 13 in the event that his or her hands slip off the handle portion 50. In this regard, the handle portion 50 is preferably tapered, as shown in FIG. 1, so that its rearward edge is thicker than its forward edge so that if the operator&#39;s fingers slip on the handle portion 50, they tend to slip toward the rearward side of the shield portions 52 where they are shielded from the cutting edge 13. 
     Furthermore, in order to facilitate safe and convenient sharpening operations, the sharpening apparatus 10 is designed and configured so that once the blade 11 is secured between the clamping fingers 17a and 17b, the user may maintain the blade 11 and the frame assembly 12 in a stationary position merely by securely gripping the handle 15 of the cutting implement. It should be noted that because of the above-mentioned longitudinal end-to-end relationship of the abrading members, progressive abrading operations may be performed without moving the user&#39;s hands on either the abrading assembly or the knife. 
     From the above discussion, one skilled in the art will readily recognize that the present invention provides a sharpening apparatus which can be safely used and operated, which accommodates various sizes, thicknesses and configurations of blades or other cutting implements to be sharpened, and which conveniently allows for relatively coarse, intermediate, and/or relatively fine abrading operations on the cutting edge of the blade without the necessity of a plurality of abrading assemblies. 
     The foregoing discussion discloses and describes exemplary embodimemnts of the present invention. One skilled in the art will readily recognize from such discussion that various changes, modifications and variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims.