The present disclosure relates generally to devices for sharpening knife blades.
Many of the wide variety of knife sharpeners that have been developed in the past fail to give truly sharp edges or even consistently good edges because of the lack of good angular control during the sharpening process. This is particularly true of “V-type” sharpeners intended to sharpen both edge facets simultaneously. Manual means for sharpening in particular are unsatisfactory because existing V-type sharpeners do not have an integral control of the angle but depend on the user to hold the blade vertically with respect to the sharpening surfaces while sharpening. To develop a really sharp edge it is important that the blades pass over the abrasive surface stroke after stroke at the same angle.
A common V-type sharpener is the crock stick sharpener, which typically includes a pair of ceramic rods that are crossed to form a V-shaped slot. The rods usually are made of abrasive material such as sintered aluminum oxide. In use, the knife edge is pulled through the crotch formed by the two rods. Unfortunately, there is no angular control and any rotational motion of the blade (deviation from vertical) or any tilting of the blade horizontally stroke to stroke will substantially reduce the chances of getting a sharp edge on the blade.
Another V-type sharpener uses a series of flat individual rectangular abrasive bars to form a V slot, but again there is no provision for angular control of the blade as it is pulled through the sharpener. This, like other V-type sharpeners, requires a skillful operator to hold the blade “vertical” during sharpening, which is an impractical requirement. Any angular variation stroke to stroke will result in reforming each of the blade facets at a new and different angle. This tends to dull the edge and possibly deform it, rather than sharpen it to a keen edge.
Thus, there is exists much room for improvement in the prior art.
The present disclosure concerns embodiments of an improved knife sharpener. According to one embodiment, the knife sharpener has an elongated sharpening member, which can be, for example, an abrasive sharpening rod. The sharpening rod can be made of any of various suitable materials, such as ceramic, porcelain, stone, and/or diamond. The sharpening member extends through a sharpening guide, which is movable in both directions along the length of the sharpening member. The sharpening guide desirably is made of a low-friction material, such as nylon, high-density polyethylene or similar polymers, to facilitate sliding of the sharpening guide relative to the sharpening member. The sharpening guide defines at least one guide slot for receiving a knife blade to be sharpened. The guide slot is configured to position a facet (i.e., one side of the blade edge) of the knife blade in sliding contact with the sharpening member and at a predetermined angle with respect to the sharpening member.
To sharpen the knife blade, the user draws the blade through the guide slot while moving the sharpening guide and the blade in the direction of the length of the guide. As the blade slides laterally and longitudinally across the sharpening surface during a sharpening stroke, the blade is held at the predetermined angle with respect to the sharpening member by the guide. Notably, the guide slot also aligns the blade at the same angle on each successive stroke to ensure a sharp blade.
In particular embodiments, a biasing member, such as a coil spring, is coupled to the sharpening guide. The biasing member resiliently urges the sharpening guide to a rest position. When sharpening a blade, the sharpening guide is moved along the length of the sharpening member against the biasing force of the biasing member. At the end of the stroke, the user reduces hand pressure on the blade to allow the sharpening guide to move back to the rest position under the force of the biasing member.
In certain embodiments, a knife sharpening kits includes multiple sharpening members of different grades of coarseness and multiple sharpening guides that are useable with any of the sharpening members. The sharpening guides are provided with guide slots that are inclined at different angles to accommodate different types of blades.
In another embodiment, a knife sharpening apparatus includes a case or housing and a knife sharpener pivotably connected to the housing. The sharpener desirably includes an elongated sharpening member and an elongated support rod extending from a rotatable base disposed in the housing. The sharpening member and the support rod are pivotable together between a down position inside the housing for storage and a generally upright position extending from the housing for use in sharpening a blade. A sharpening guide is slidably disposed on the sharpening member and has a guide slot for positioning a blade at a predetermined angle with respect to the sharpening member and in sliding contact with the sharpening member. The support rod extends through a groove formed in the sharpening guide to limit rotation of the sharpening guide while permitting sliding of the sharpening guide along the length of the sharpening member.
The housing can include storage space for one or more removable sharpening guides having different pre-set sharpening angles. The housing also can include a lid for mounting a flat sharpening stone that can be used to sharpen knife blades and other tools in a conventional manner.
The foregoing and other features and advantages of the invention will become more apparent from the following detailed description of several embodiments, which proceeds with reference to the accompanying figures.
As used herein, the singular forms “a,” “an,” and “the” refer to one or more than one, unless the context clearly dictates otherwise.
As used herein, the term “includes” means “comprises.”
As used herein, the term “knife” can include any cutting device or utensil having at least one cutting blade, which may be fixed, foldable or partially or wholly retractable relative to a handle or grip. Examples of cutting devices and utensils included within the term “knife” include, without limitation, kitchen knives, butcher's knives, chefs knives, sporting knives, box cutters knives, pocket knives, letter openers or bodkins, and the like.
Referring first to
The sharpening member 14 desirably comprises a hard, abrasive material, such as ceramic, porcelain, stone, diamond, or any of various other suitable materials. The sharpening member can be made entirely of an abrasive material. Alternatively, the sharpening member can have an inner core (which can be a non-abrasive material) and an outer layer of abrasive material overlaying the core.
The sharpening member 14 in the illustrated configuration is an elongated rod, which can be generally cylindrical as shown, or can have other cross-sectional profiles, such as a square, rectangular, oval, ellipse, or combinations thereof. In a specific implementation, the rod can be generally cylindrical with one or more flat sharpening surfaces extending the majority of the length of the rod.
The sharpening member 14 can be mounted on the base by inserting the lower end portion into an aperture (not shown) in the base. Similarly, the cap 18 can be mounted on the sharpening member 14 by inserting the upper end portion of the sharpening member into an aperture (not shown) in the lower surface of the cap. The sharpening member desirably is removable from the base 12, the cap 18, and the sharpening guide 16 so that another sharpening member that is more or less coarse can be used and/or a different sharpening guide can be used. In particular embodiments, for example, an assembly or kit includes two or more similarly shaped sharpening members of different grades of coarseness. The kit also can include different sharpening guides configured to accommodate different blade thicknesses or blade angles, as further described below.
In alternative embodiments, the cap and/or the base can be permanently mounted to the sharpening member.
The sharpening member 14 extends through a central opening 22 (
As best shown in
While the illustrated embodiment shows the guide surfaces of the slots 24, 26 as being generally parallel, this is not a requirement. For example, a guide slot can be slightly tapered from the top of the slot to the bottom of the slot to correspond to the taper of a knife blade.
As shown in
The incline of the guide slot with respect to the sharpening member can vary depending on the type of knife to be sharpened. In certain embodiments, the incline of the guide slot is in the range from about 15 degrees to about 25 degrees, although greater or smaller angles also can be used. As mentioned above, the sharpening guide 16 desirably is removable from the sharpening member 14. As such, a set of two or more sharpening guides having guide slots oriented at different angles can be provided. In one embodiment, for example, a set of sharpening guides includes a first sharpening guide having guide slots inclined at about 15 degrees with respect to the sharpening member and a second sharpening guide having guide slots inclined at about 20 degrees with respect to the sharpening member. The first sharpening guide can be used, for example, for knives having relatively finer cutting edges, such as pocket knives. The second sharpening guide can be used, for example, for hardier knives, such as choppers.
The width of the gap between the guide surfaces of a slot 24, 26 desirably is slightly greater than the thickness of the blade to be sharpened so that the surfaces of the guide slot contact the opposing surfaces of the blade. To accommodate blades of varying thicknesses, a set of sharpening guides can include multiple sharpening guides of the same sharpening angle but different gap widths. Alternatively, each sharpening guide can have a first set of guide slots and a second set of guide slots formed below the first set of guide slots. In this alternative configuration, the first and second sets of guide slots can have the same sharpening angle but different gap widths. In a more sophisticated embodiment, a sharpening guide can be configured to vary the gap width between guide surfaces. For example, a portion of the sharpening guide can be movable to vary the gap width between the guide surfaces. The movable portion can be spring loaded to maintain a minimum gap width and increase the gap width upon insertion of a knife blade.
When at rest, the spring 20 resiliently urges the sharpening guide 16 to an initial or rest position adjacent the cap 18 (as shown in
At the beginning of a sharpening stroke, the handle end of the blade 40 is positioned in one of the guide slots of the sharpening guide 16 such that a facet of the cutting edge contacts the sharpening member 14 (
Another approach for sharpening the blade 40 is as follows. With the sharpening guide at its rest position, the blade is drawn rearwardly and downwardly until just the tip of the blade remains in the sharpening guide. At this point, hand pressure on the blade is lightened to allow the spring 20 to lift the sharpening back to its rest position while the blade is pushed forwardly through the guide slot to ready the blade for another stroke. This sequence can be repeated as necessary, after which the blade is positioned in the opposite guide slot to sharpen the other facet of the blade in the same manner. After the majority of the length of the blade is sharpened, the tip of the blade can be sharpened in one or more short strokes.
In a less sophisticated embodiment, a fixed or stationary sharpening guide can be retained at a fixed position on a sharpener member. In this embodiment, the sharpening guide aligns the blade at a predetermined angle with respect to the sharpening member as the blade is stroked laterally across the sharpening member, but does not allow any longitudinal movement of the blade relative to the sharpening guide.
The lid 104 is connected to the case 102 by a pivot pin (not shown) so that the lid can be pivoted between a down position covering the upper opening of the case (
The sharpener 106 in the illustrated configuration generally comprises a rotatable base 112 mounted in the case 102, an elongated sharpening member 114 (e.g., an abrasive rod) extending from the base 112, a support rod 116 extending from the base 112 in generally parallel relationship with the sharpening member 114, a sharpening guide 118 slidably disposed on the sharpening member 114, a coil spring 120 disposed on the sharpening member 114 between the sharpening guide 118 and the base 112, and a cap, or end piece, 122 mounted to the ends of the sharpening member 114 and the support rod 116.
In the illustrated embodiment, the upper end portion of the sharpening member 114 extends into a similarly shaped opening (not shown) in the bottom of the end piece 122. The end piece 122 can be secured in place by a screw 140 extending through an opening 142 in the end piece and tightened into a threaded opening 144 in the upper end portion of the support rod 116 (
As shown in
The support 124 can be retained in the case 102 using any techniques or mechanisms, such as by securing the support with an adhesive or a mechanical fastener (e.g., a screw). The base 112 in the illustrated embodiment is secured to the case 102 by screws 150. Referring to
When the sharpener 106 is pivoted to the upright position, the sharpening member 114 and the support rod 116 can be inserted into respective openings 130, 134 in the support 124 to prevent rotation of the base, thereby locking the sharpener in place for use (as best shown in
Like the embodiment shown in
As best shown in
The guide portion 160 desirably is sufficiently resilient form a “snap-fit” connection with sharpening member to retain the guide portion 160 in place between the end portions 162, 164 of the sliding portion 158 during use. As used herein, a “snap-fit” connection means a releasable connection between two bodies having opposing surfaces, which connection is formed by resiliently deforming at least one of the bodies so as to allow the opposing surfaces to be placed in an interlocking relationship with each other. To connect the guide portion 160, the guide portion is positioned against the sharpening member 114 between the end portions 162, 164 of the sliding portion 158. Sufficient pressure is then applied to the guide portion to cause the guide portion to deform slightly and allow opposing edges 170 (
Guide slots 172 and 174 for a receiving a knife blade (e.g., knife blade 40 shown in
As best shown in
The sharpener 106 can be used to sharpen knife blades in the manner described above in connection with the sharpener 10 (
The present invention has been shown in the described embodiments for illustrative purposes only. The present invention may be subject to many modifications and changes without departing from the spirit or essential characteristics thereof. We therefore claim as our invention all such modifications as come within the spirit and scope of the following claims.
The present application claims the benefit of U.S. Provisional Application No. 60/621,329, filed Oct. 22, 2004, which is incorporated herein by reference.
Number | Date | Country | |
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60621329 | Oct 2004 | US |