Tool Sharpener

Abstract

Apparatus and method for sharpening tools such as knives and scissors. The apparatus comprises an elongated rod coated with a sharpening surface of particles of synthetically produced, polycrystalline diamond. The rod is set into a handle. A tool is sharpened by stroking an edge of the tool against the sharpening surface of the rod.

Parent Case Text

This application is a continuation-in-part of copending U.S. Pat. application Ser. No. 232,777 filed Mar. 8, 1972, now abandoned.

Description

BACKGROUND

1. Field of the Invention

The invention relates to a tool sharpener and more particularly to a sharpening device having a surface covered with dust-like particles of synthetically produced, polycrystalline diamond.

2. The Prior Art

Sharpening devices for knives and other tools are wellknown in the art. Such devices, particularly when adapted for knife sharpening, are known as steels in the meat cutting industry. A skilled meat cutter requires a sharp knife so that he can carve meat in a fast and effective manner and without scoring or feathering the meat. The knife, dulled through use, requires frequent sharpening. Consequently, a steel is used to bring the blade of the knife back into a highly sharpened condition.

Traditionally, a steel is an elongated fluted round metal rod that is set into a handle. The handle of the steel is gripped in one hand and the knife in the other. The edge of the blade is then stroked against the fluted rod in a generally arcuate sweeping motion towards the handle of the steel. As the blade of the knife engages each ridge of the fluted rod the blunt edge of the blade is gradually reshaped or polished resulting in a more acute edge. Usually the blade is further polished by stroking the blade against another steel having a sharpening surface comprised of smooth metal. To improve upon the fluted rod, steels have been produced having a sharpening surface made of a carbonaceous substance embedded in a ceramic material. Each carbonaceous particle acts as a sharpening edge as a knife is urged over the ceramic surface of the steel. However, the ceramic material is easily shattered when the steel is inadvertently dropped thereby making it a less desirable material.

Other patents teach the use of diamond dust or particles as the abrasive constituent in a honing device, for example, see U.S. Pat. Nos. 2,379,569 and 3,288,580. However, none of the cited prior art teaches the distinct and patentably unique concept of this invention of using polycrystalline synthetically produced diamond particles as the abrasive constituent of their honing devices.

Advantageously, it has been found that polycrystalline synthetic diamond particles exhibit surprisingly superior characteristics as compared to natural diamond particles when used as a tool sharpener. A natural diamond particle offers relatively very few cutting points. A natural diamond particle of the size used in a tool sharpening instrument generally has from 8 to 18 cutting points. Natural diamond particles of this size are usually single crystals which accounts for their having a very limited number of cutting points or edges. On the other hand, a polycrystalline synthetic diamond particle offers thousands of sharp cutting edges per particle, and thus a honing device comprising synthetically produced polycrystalline diamond particles as the cutting medium exhibits superior cutting characteristics.

BRIEF DESCRIPTION AND OBJECTS OF THE INVENTION

According to the present invention an improved sharpening steel is made of polycrystalline, synthetically produced diamond dust bonded to a rod. Not only is the steel durable and shatter-proof, but the blade of the knife that is urged over the sharpening surface of the steel is more quickly sharpened. Each polycrystalline diamond particle has thousands of cutting edges which act as sharpening surfaces leaving the edge of the knife blade finely serrated. The finely serrated edge of the knife blade is a far more efficient cutting tool than a conventional smooth edge blade.

It is therefore a primary object of the present invention to provide an improved sharpening tool.

It is another primary object to provide a novel sharpening tool which is durable and shatter-proof.

It is another significant object of this invention to provide an improved sharpening tool incorporating on the surface thereof synthetically produced polycrystalline diamond particles.

These and other objects and features of the present invention will become more fully 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 a presently preferred sharpening device embodiment of the invention;

FIG. 2 is an exploded fragmentary view of a knife blade that has been sharpened by the device of FIGS. 1, 3, 4 and 5;

FIGS. 3 and 4 are perspective views of a presently preferred sharpening device embodiment of the invention showing the device in its extended and folded positions, respectively;

FIG. 5 is a longitudinal cross-sectional view of the foldable sharpening device of FIGS. 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is now made to the drawings and particularly to FIG. 1. A presently preferred embodiment of the invention generally designated 10 has an elongated tapered metal rod generally designated 12 rigidly set into a handle generally designated 14. Fine particles of synthetically produced polycrystalline diamond dust have been bonded to the surface 16 of rod 12. Any suitable technique could be used for bonding diamond dust to the rod. An example of an available bonding technique can be found in U.S. Pat. No. 2,360,798.

Handle 14 is generally cylindrical in configuration and is made of molded plastic or other suitable material. A hand guard generally designated 18 is integral with handle 14 and is positioned perpendicularly about the axis of rod 12 at the boundary between rod 12 and handle 14. Hand guard 18 is preferably triangular in configuration having a large enough surface area so that projections 20 protect a hand gripping handle 14 against the blade of the knife that is being urged down rod 12 towards handle 14.

Handle 14 is made of sections 22, 24 and 26. Cylindrical section 22 contains rod 12. Section 22 tapers inwardly to section 24. Section 24 accommodates a thumb (not shown) when handle 14 is gripped in the hand. Section 24 gradually tapers outwardly to section 26. Section 26 is preferably scored or fluted to facilitate a firm and secure hand grip. An eyelet 28 is set into the end of handle 14 so that the steel 10 may be hung on a hook (not shown) when not in use.

In use, the handle 14 of steel 10 is gripped in a hand (not shown). A knife (not shown) is gripped in the other hand and the blade of the knife generally designated 30 (see FIG. 2) is urged against surface 16 of rod 12. Edge 32 of knife blade 30 is urged along surface 16 in a generally arcuate sweeping motion toward handle 14. Grooves 34 are formed in knife blade 30 as knife blade 30 engages the synthetically produced polycrystalline diamond particles in surface 16. Grooves 34 in knife blade 30 cause edge 32 to be serrated. The serrated edge 32 gives the knife blade 30 a more efficient cutting edge and allows the blade to pass more readily through meat or other material. Where the blade is very dull, it has been found desirable to hone the blade with a circular scrubbing motion. Because of the unusual sharpening ability of this invention, special sharpening stones and like devices are unnecessary.

Referring to FIG. 3, another presently preferred tool sharpener embodiment is illustrated. In the FIG. 3 embodiment, an elongated metal rod 50 has bonded on the surface thereof particles of synthetically produced polycrystalline diamond as indicated at 52. The rod 50 is forwardly tapered at 51 and preferably has a hollow interior 64. The hollow interior has been found useful to reduce the overall weight of the tool without adversely affecting the utility of the tool.

The metal rod 50 is secured in an annular collar 56. Collar 56 is integrally mounted upon the trailing end 61 of metal rod 50 in, for example, a press-fit relationship with the diametrally reduced bore 60. Desirably, the collar 56 may be made of two bushings secured back to back to facilitate production and assembly of the collar 56. It has also been found desirable to place resilient O-rings (not shown) within the annulus 58 and bore 63 adjacent the diametrally reduced bore 60. The O-rings have been found to minimize the machining effect on threads as the collar is tightened upon the handle 54. Thus, binding and galling of the threads is eliminated.

The forward end 57 of the collar 56 has a smooth exterior surface and defines an annulus 58 which is interiorly threaded. The annulus 58 has a diameter which is greater than bore 60 and is in communication therewith.

The trailing end 59 preferably has an exteriorly knurled surface 62 to provide a gripping surface for the purpose hereinafter more fully described. Interiorly, the trailing end 59 defines enlarged bore 63 having a diameter which is the same as the diameter of annulus 58. Bore 63 is similarly interiorly threaded, the threads having a pitch and size which match those of annulus 58.

A handle 54 is formed in tubular configuration which serves both as a handle and as a sheath when metal rod 50 is inserted therein for carrying purposes as shown in FIG. 4. As shown in FIG. 5, the handle 54 has an exteriorly threaded leading end 65 removably attached to the collar 56 at bore 63. The hollow 67 of handle 54 opens to the exterior at the leading end 65. Metal rod 50 is insertible into handle 54 in a sheath relationship represented by broken lines 50a. Accordingly, metal rod 50 with its bonded diamond particles 52 is suitably protected by handle/sheath 54 when in the broken-line position 50a.

To place the rod 50 in the broken-line position 50a (FIG. 5), the collar 56 is initially separated from the handle 54 by rotating the collar relative to the handle. The knurled surface 62 provides an improved finger-grip to facilitate the separation. After separation of the collar 56 from handle 54, the orientation of rod 50 is reversed and the rod inserted axially into the hollow 67 of handle 54. The collar 56 is then threadedly secured to the handle 54 at annulus 58. Accordingly, the embodiment of FIGS. 3-5 is both lightweight and compact. Weight reduction is of considerable importance when a tool sharpener according to the illustrated embodiment is carried by hikers, backpackers and the like. Moreover, a significant reduction in the overall length of the honing device is achieved quite readily by the simple expedient of placing the working surface portion of the tool inside the handle member, thus substantially reducing the overall length of the tool sharpener. In a non-folding tool sharpener as shown in FIG. 1, a hollow metal rod and hollow handle could also be used to achieve significant weight reductions which is of considerable benefit to the user thereof.

The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

What is claimed and desired to be secured by United States Letters Patent is:

1. A tool sharpener comprising:

a generally cylindrical elongated sharpening rod;

a coupling sleeve mounted to one end of the sharpening rod and having an outside diameter greater than that of the rod and comprising threaded opposing internal bores within the sleeve of an internal diameter greater than the diameter of the rod, each bore extending inwardly less than half the length of the sleeve; and

a generally hollow handle having an exteriorly threaded cylindrical end capable of threadedly engaging either of the internal bores of the coupling sleeve and of internally accommodating the sharpening rod when coupled with the end of the sleeve from which the rod extends.

2. A tool sharpener comprising:

a hollow elongated metal rod having trailing and leading ends and terminating in a conical tip at the leading end, the entire exposed surface of the rod having synthetic polycrystalline diamond particles bonded thereto;

a cylindrical sleeve rigidly affixed to the trailing end of the rod and extending beyond the trailing end of the rod, the sleeve having an outside diameter which is greater than the outside diameter of the rod and comprising opposed internally threaded bores separated by a diametrally reduced bore into which the rod is rigidly mounted; and

a cylindrical handle hollowed to an inside diameter which is greater than the outside diameter of the rod, the handle having one open end at least a portion of which has an outside diameter which is less than the outside diameter of the sleeve, said open end being exteriorly threaded to threadedly engage to with the interior threads of both opposed bores of the sleeve, thereby permitting the rod to be threadedly attached to the handle both in a forwardly projecting position and in a concealed position with the handle.