POWERED SHARPENER WITH MANUAL HONE STAGE
Apparatus and method for sharpening a cutting tool, such as a kitchen knife. A sharpener has a base unit and one or manual sharpening modules. The base unit has a housing which encloses at least one flexible abrasive disc rotated by an electric motor. Each flexible abrasive disc is adjacent a powered sharpening stage to perform a primary sharpening operation upon the tool. Each manual sharpening module may be removably attachable to the base unit and has a manual sharpening stage that incorporates at least one sharpening element to perform a secondary sharpening operation upon the tool. Each manual sharpening module further has a powered stage guide surface to form a portion of a corresponding powered sharpening stage. When two powered sharpening stages are used, the manual sharpening module(s) can be individually placed between the powered sharpening stages to provide opposing powered stage guide surfaces for each.
The present application makes a claim of domestic priority to U.S. Provisional Patent Application No. 62/854,077 filed May 29, 2019, the contents of which are hereby incorporated by reference.
BACKGROUNDCutting tools are used in a variety of applications to cut or otherwise remove material from a workpiece. A variety of cutting tools are well known in the art, including but not limited to knives, scissors, shears, blades, chisels, machetes, saws, drill bits, etc.
A cutting tool often has one or more laterally extending, straight or curvilinear cutting edges along which pressure is applied to make a cut. The cutting edge is often defined along the intersection of opposing surfaces (bevels) that intersect along a line that lies along the cutting edge.
In some cutting tools, such as many types of conventional kitchen knives, the opposing surfaces are generally symmetric; other cutting tools, such as many types of scissors and chisels, have a first opposing surface that extends in a substantially normal direction, and a second opposing surface that is skewed with respect to the first surface.
Complex blade geometries can be used, such as multiple sets of bevels at different respective angles that taper to the cutting edge. Scallops or other discontinuous features can also be provided along the cutting edge, such as in the case of serrated knives.
Cutting tools can become dull over time after extended use, and thus it can be desirable to subject a dulled cutting tool to a sharpening operation to restore the cutting edge to a greater level of sharpness. A variety of sharpening techniques are known in the art, including the use of grinding wheels, whet stones, abrasive cloths, abrasive belts, etc.
SUMMARYVarious embodiments of the present disclosure are generally directed to an apparatus and method for sharpening a cutting tool, such as but not limited to a kitchen knife.
In some embodiments, a sharpener is provided for sharpening a cutting tool having a cutting edge. The sharpener has a housing, a flexible abrasive disc mounted to a central shaft within the housing to provide a powered sharpening stage, an electric motor disposed within the housing and configured to rotate the flexible abrasive disc in a selected rotational direction, and a manual sharpening module removably attachable to the housing at a location adjacent the powered sharpening stage. The manual sharpening module has a powered stage guide surface configured to support a first side of the cutting tool during presentation of an opposing second side of the cutting tool against the flexible abrasive disc to effect a primary sharpening operation upon the cutting edge. The manual sharpening module further has an elongated access slot to facilitate movement of the cutting tool against a manual sharpening element along a cutting tool drawing axis to effect a secondary sharpening operation upon the cutting edge.
In related embodiments, a sharpener is provided for sharpening a cutting tool having a blade with opposing first and second sides that converge to an intervening cutting edge. The sharpener includes a housing, first and second flexible abrasive discs mounted to a central shaft in a spaced apart relation within the housing to provide opposing first and second powered sharpening stages, an electric motor disposed within the housing and configured to rotate the first and second flexible abrasive discs in a selected rotational direction, and a manual sharpening module affixed to the housing between the first and second powered sharpening stages. The manual sharpening module has opposing first and second guide surfaces configured to respectively support the opposing first and second sides of the blade during presentation of the corresponding second and first sides of the blade against the respective first and second flexible abrasive discs. The manual sharpening module further has a honing stage having an elongated access slot to facilitate presentation of the cutting edge against a manual honing element disposed within the access slot.
In further related embodiments, a method is provided for sharpening a cutting tool having opposing first and second sides that converge to an intervening cutting edge. The method includes inserting the cutting tool into a first powered sharpening stage of a powered sharpener to perform a primary sharpening operation upon the cutting edge, the powered sharpener having a housing which encloses an electric motor configured to rotate a first flexible abrasive disc in a selected rotational direction, and a removably attachable manual sharpening module having a main body with a powered stage guide surface and an interior manual sharpening element, the powered stage guide surface supporting the second side of the cutting tool during contacting engagement of the first side of the cutting tool against the first flexible abrasive disc; and drawing the cutting tool through an elongated slot of the manual sharpening module to draw the cutting tool against the manual sharpening element to perform a secondary sharpening operation upon the cutting edge.
These and other features and advantages of various embodiments can be understood from a review of the following detailed description in conjunction with the accompanying drawings.
Various embodiments of the present disclosure are generally directed to a powered knife and tool sharpener, and to a method for using the same. As explained below, the sharpener includes a base unit with powered abrasive media and one or more manual sharpening modules with manually activated abrasive media. Within the base unit, an interior motor drives a central transverse shaft to which one or more flexible rotatable abrasive discs are mounted. It is contemplated that two discs will be used, one on each side of the shaft, but this is not necessarily required. The motor shaft is parallel to the disc shaft and power transfer takes place using a power transfer mechanism such as a belt and pulley system.
Stationary sharpening guides are provided to enable the user to repetitively present opposing sides of a knife or other cutting tool against the interior facing rotating surfaces of the abrasive disc(s). The flexible discs may incorporate sandpaper or similar media of a flexible nature adapted to provide an abrasive surface that removes material from the presented cutting tool to conform an outer shape of the cutting tool to a desired cutting geometry.
In at least some embodiments, the discs can be rotated at two different speeds, a slower “sharp” setting and a faster “shape” setting. Each of these can be activated by pressing respective buttons located near the rear of the sharpener housing, which in turn causes the motor to operate at different settings to effect the desired sharpening operation.
A manual sharpening module is removably attached to a central top portion of the base unit. When two discs are used, the manual sharpening module may be positioned between the opposing rotatable abrasive discs. The manual sharpening module has a central slot through which the user can insert the blade after the powered sharpening operations using the abrasive discs. The manual sharpening module can be used while the module is affixed to the base unit, or can be used in a hand-held fashion as the user holds the module in the user's hand or places the module on a suitable support surface such as a counter-top. The purpose of the manual sharpening module is to apply a fine (hone) sharpening operation upon the cutting edge of the tool after the tool has been sharpened using the powered abrasive.
The module incorporates a manual sharpening element, which may take the form of a double canted sharpening wheel with two frusto-conical surfaces in facing relation to one another. The wheel may be formed of a single piece of ceramic, and is canted at an acute angle with respect to the central slot. Advancement and retraction of the blade provides a honing action upon the blade as the blade is concurrently acted upon by both of the frusto-conical discs. The honing action can operate to remove burrs and provide refined shaping of the cutting edge. Other arrangements for the manual sharpening element can be used, including but not limited to a pair of intersecting sharpening elements such as abrasive wheels, rods, plates, blocks, etc.
In further embodiments, two different manual sharpening modules are provided for use with the base unit of the sharpener. One manual sharpening module is configured for use with knives having relatively thin blades, such as kitchen knives, and the other sharpening module is configured for use with knives having relatively thick blades, such as pocket knives. The different manual sharpening modules may be adapted to provide different sharpening geometries, such as different shapes or angles, to the cutting tool. As noted above, the modules can be used either while attached to the housing, while holding the module in the user's hand, or by placing the modules on a flat base surface.
Outside surfaces of each module provide angled support (guide) surfaces for use during the sharpening against the abrasive discs in the base unit. The different manual sharpening modules can provide different presentation angles of the respective blades against the rotating media. In some embodiments, the pocket knife module has a larger sharpening angle (e.g., about 25 degrees) as compared to the kitchen knife module (e.g., about 20 degrees). In this way, a selected sharpening module can not only provide the desired coarse ground sharpening angle as the tool is subjected to the powered coarse sharpening operation, but can also provide a suitable corresponding fine honing operation to provide a desired fine ground sharpening angle as the tool is subsequently honed.
Both modules may be removed and attached to the housing by sliding the associated module forward, and engaging a rigid hook that locks the associated module into place. Removal of the module allows a top cover of the base unit to be raised using a set of hinges, providing easy access to the abrasive discs and other interior aspects of the sharpener. Contrawise, installment of the module onto the rigid hook locks the top cover in place. In some cases, a stationary scissors support is formed in the top surface of the base unit to allow a user to sharpen a pair of scissors against a selected one of the abrasive discs when the module is removed from the base unit.
The abrasive disc(s) may be mounted to the central shaft using annular disc retainers. The disc retainers cover a substantial portion of the backing layer of each abrasive disc, such as by having a radius that is nominally about 50% of the radius of the associated abrasive disc. This places an edge of the disc retainer at a location below a contact area on the opposing side of the associated disc to provide a biasing force to increase the surface pressure and material take off (MTO) rate during the sharpening operation. In some cases, the retainer operates to provide higher surface pressure for thicker blades and reduced surface pressure for thinner blades.
The powered flexible abrasive discs can take a variety of constructions. In some embodiments, the discs are formed of double sided sandpaper so as to have opposing outer abrasive surfaces on a medial backing layer. Other constructions can be used, such as a flexible abrasive disc with a foam intermediate layer that compresses to allow conformal shaping during the sharpening operation.
These and other features and advantages of various embodiments can be understood beginning with a review of
As explained in greater detail below, the module 104 is generally configured for relatively thinner blades (e.g., the “kitchen knife module”) and the module 106 is generally configured for relatively thicker blades (e.g., the “pocket knife module”). It will be appreciated that the provision of two (or more) modules is merely exemplary and is not necessarily required. Moreover, the removable nature of the modules is not necessarily required in at least some embodiments.
As further depicted in
Enclosed within the housing 108 are a pair of rotatable flexible abrasive discs 118, 120. The discs 118, 120, also sometimes referred to as the first and second discs, are arranged for rotation about a central shaft 122 which is rotated using a drive system having an electric motor 124, a belt 126 and pulley 128, as generally depicted in
A pair of sharpening ports 130, 132 (also sometimes referred to as powered sharpening stages) are provided in the top cover 112 to provide access to the interior surfaces of the abrasive discs 118, 120. Opposing guide surfaces 134, 136 are provided on each of the sharpening modules 104, 106. In this way, during a powered sharpening operation, a user can place opposing sides of a blade of a knife against the respective guide surfaces 134, 136 in succession to sharpen the cutting edge of the knife against the respective abrasive discs 118, 120. For this reason, the guide surfaces may also be referred to as powered stage guide surfaces or outer guide surfaces. It will be noted that in this configuration, the discs 118, 120 both rotate in the same direction with respect to the cutting tool in each of the sharpening stages (e.g., down and across, etc.).
Each of the modules 104, 106 includes a central aperture (slot) 146 that extends in a longitudinal direction along the overall length of the associated module. The slot 146, also sometimes referred to as a manual sharpening stage or a honing stage, provides non-contacting access to an interior manual sharpening member 148, which in
While not limiting, it is contemplated that the sharpening wheel will be formed of ceramic, although other materials may be used. A double canted sharpening wheel such as 148 provides a honing action on opposing sides of the blade along the intersection of the respective axes of the frusto-conical surfaces 150, 152. The slot allows the blade of the knife to be advanced and retracted along the length of the cutting edge against the wheel.
Referring again to the base unit 102 in
The disc retainers 170, 172 are nominally identical and each have a central annular groove 176. The groove 176 accommodates the belt 128 (see
As depicted in
Because each retainer is offset from the contact area, the flexible disc can be deflected back and follow the contour of the blade. The edge of the retainer disc is recessed as shown so that, generally, higher surface pressure is applied for thicker blades and lower surface pressure is applied to thinner blades. A central aperture (hole) 179 in the disc allows the disc to slip over the associated threaded end 166, 168 of the central shaft 160 during disc installation.
Returning to
A primary (or powered) sharpening operation can thus be carried out by presenting each side of the blade 180 in the respective sharpening slots 130, 132 in turn. In some cases, the motor 124 can be configured to rotate the respective discs 118, 120 at a fixed rotational rate suitable for a primary sharpening operation. In other cases, the motor 124 can be configured to operate at different speeds and/or over different time periods to accomplish different forms of sharpening.
In one non-limiting embodiment, a primary sharpening operation using the flexible discs 118, 120 can include a sharpening cycle which includes a first higher (sharpening) speed to quickly abrade the bevel and a second lower (refine) speed to reduce/remove any burr formed in the first higher speed. The times for each of the speeds is controlled by a motor control circuit (not shown) coupled to the motor. This sequence can be carried out by the user depressing a single button on the unit.
After the sharpening cycle, a second shaping cycle can be initiated by an alternate input from the user. The shaping cycle provides a third higher (shape) speed/time to re-shape/re-store excessively dull or damaged edges followed by a low (refine) speed to remove/reduce any burr formed in the previous high speed operation. This third higher shape speed increases a component of centrifugal force acting on the disc and subsequently further increases the material take off (MTO) of the shape step.
The reduction in speeds provided during the refine speed of sharpening and shape cycles reduces a component of centrifugal force acting on the disc and subsequently further reduces the MTO of the refine step.
During a manual (secondary) sharpening operation, including after the conclusion of a powered (primary) sharpening operation as described above against the discs 118, 120, the user can place the blade 180 into the slot 146 (honing stage) and advance/retract the blade against the wheel 148 a suitable number of times, such as ten times (10×), along a cutting tool drawing axis 186 as depicted by reciprocal arrow 186A. The user may grasp a handle 188 affixed to the blade 180 of the knife 190 to manipulate the blade during both primary and secondary sharpening operations in the respective powered and manual sharpening stages (e.g., 130, 132, 146). The honing operation refines a cutting edge 191 established at the intersection of the respective sides 182, 184 of the blade.
With reference again to
Various internal elements described above are depicted in
A pair of disc-shaped magnets 198 are provided in the base member 110 below the respective flexible discs 118, 120. The magnets collect collect swarf (particles, etc.), via magnetic attraction, that have been removed from the blades during primary sharpening operations using the discs.
It is noted that the aforementioned pulley 128 is affixed to a motor shaft 199 driven by the electric motor 124. The motor shaft 199 is nominally parallel to the central shaft 160 supporting the discs 118, 120. The central shaft is housed within the central boss 196 but is depicted including in
As described above, after sharpening the blade on a flexible abrasive disc the user may place the blade 180 (
Another configuration can provide powered sharpening ports to enable the cutting tool to be alternately presented against each side of the double sided abrasive disc to respectively sharpen each side of the tool in turn. In this latter case, multiple powered sharpening guide surfaces can be incorporated into the manual sharpening module and the manual sharpening element(s) within the manual sharpening module may be offset from the powered sharpening stages rather than necessarily located therebetween.
The abrasive layer(s) can take any number of suitable forms and abrasiveness (grit) levels. In some cases, the layers are formed of sandpaper media with a grit in the range of from about 120-240. Other ranges and forms of abrasive particles can be used as desired. The backing layer is any suitable flexible material such as cloth or paper. It is contemplated that the abrasive layers on the respective discs will have a common abrasiveness level, but this is not necessarily required in that one surface could have a more coarse grit and the other surface could have a more refined grit.
While it is contemplated that the various embodiments discussed herein have used powered abrasive media in the form of flexible abrasive discs, aspects of the various embodiments can be utilized with other forms of moveable media, such as but not limited to endless abrasive belts, rigid grinding wheels, etc.
It is to be understood that even though numerous characteristics and advantages of various embodiments of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the disclosure, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Claims
1. A sharpener for sharpening a cutting tool having a cutting edge, the sharpener comprising:
- a housing;
- a flexible abrasive disc mounted to a central shaft within the housing to provide a powered sharpening stage;
- an electric motor disposed within the housing and configured to rotate the flexible abrasive disc in a selected rotational direction; and
- a manual sharpening module removably attachable to the housing at a location adjacent the powered sharpening stage, the manual sharpening module having a powered stage guide surface configured to support a first side of the cutting tool during presentation of an opposing second side of the cutting tool against the flexible abrasive disc to effect a primary sharpening operation upon the cutting edge, the manual sharpening module further having an elongated access slot to facilitate movement of the cutting tool against a manual sharpening element along a cutting tool drawing axis to effect a secondary sharpening operation upon the cutting edge.
2. The sharpener of claim 1, wherein the flexible abrasive disc is a first flexible abrasive disc, the powered sharpening stage is a first powered sharpening stage and the powered stage guide surface is a first powered stage guide surface, wherein the sharpener further comprises a second flexible abrasive disc mounted to the central shaft within the housing to provide a second powered sharpening stage, wherein the manual sharpening module further has a second powered stage guide surface configured to support the second side of the cutting tool during presentation of the first side of the cutting tool against the second flexible abrasive disc, and wherein the manual sharpening module is disposed between the first and second powered sharpening stages.
3. The sharpener of claim 1, wherein the powered stage guide surface is skewed with respect to the cutting tool drawing axis by an intervening angle of from about 10 degrees to about 30 degrees.
4. The sharpener of claim 1, wherein the electric motor has a motor shaft to which a pulley is affixed, a power transfer belt extends from the pulley to the central shaft to transfer power from the electric motor to the central shaft, and the central shaft and the motor shaft are nominally parallel.
5. The sharpener of claim 1, wherein the powered sharpening stage is formed by attachment of the manual sharpening module to a top surface of the housing so that the powered stage guide surface forms one side of the powered sharpening stage and a portion of the housing forms an opposing second side of the powered sharpening stage.
6. The sharpener of claim 1, wherein the housing comprises a base member and a top cover connected to the base member using a hinge assembly, wherein a rigid hook extends from the base member through an opening in the top cover to engage the manual sharpening module and lock the top cover to the base member, and wherein removal of the manual sharpening module from the hook enables the top cover to be pivoted with respect to the base member via the hinge assembly to provide user access to the first and second flexible abrasive discs.
7. The sharpener of claim 1, wherein the manual sharpening element of the manual sharpening module comprises a sharpening wheel.
8. The sharpener of claim 7, the sharpening wheel comprising a pair of facing frusto-conical surfaces and mounted at a selected acute angle with respect to the slot such that presentation and rolling of the cutting edge along the wheel provides compressive forces on opposing sides of the cutting tool as the cutting tool is retracted along the cutting tool drawing axis.
9. The sharpener of claim 1, wherein the manual sharpening element of the manual sharpening module comprises at least a selected one of an abrasive block, an abrasive rod, an abrasive disc or a metal plate.
10. A sharpener for sharpening a cutting tool having a blade with opposing first and second sides that converge to an intervening cutting edge, the sharpener comprising:
- a housing;
- first and second flexible abrasive discs mounted to a central shaft in a spaced apart relation within the housing to provide opposing first and second powered sharpening stages in which abrasive surfaces of the respective first and second flexible abrasive discs move in a common direction with respect to the cutting tool;
- an electric motor disposed within the housing and configured to rotate the first and second flexible abrasive discs in a selected rotational direction; and
- a manual sharpening module affixed to the housing between the first and second powered sharpening stages, the manual sharpening module having opposing first and second guide surfaces configured to respectively support the opposing first and second sides of the blade during presentation of the corresponding second and first sides of the blade against the respective first and second flexible abrasive discs, the manual sharpening module comprising a honing stage having an elongated access slot to facilitate presentation of the cutting edge against a manual honing element disposed within the access slot.
11. The sharpener of claim 10, wherein the manual honing element of the manual sharpening module comprises a pair of intersecting elements that form a v-shaped channel through which the cutting tool is configured to be drawn during a honing operation.
12. The sharpener of claim 10, wherein the manual honing element of the manual sharpening module comprises at least a selected one of a frusto-conically shaped skew wheel, a pair of steel plates, a pair of abrasive rods, a pair of rotatable discs, or a single abrasive block.
13. The sharpener of claim 10, further comprising first and second annular disc retainers configured to threadingly engage opposing first and second ends of the central shaft to secure the first and second rotatable flexible abrasive discs thereto, each of the first and second annular disc retainers extending a portion of an overall radius of the associated first or second rotatable flexible abrasive disc to provide a bias force to an opposing second side of the associated first or second rotatable flexible abrasive disc during presentation of the cutting edge of the cutting tool against a contact area on a first side of the associated first or second rotatable flexible abrasive disc.
14. The sharpener of claim 10, wherein each of the first and second flexible abrasive discs is characterized as a single-sided abrasive disc having an abrasive layer on a first side and a non-abrasive backing layer on an opposing second side.
15. The sharpener of claim 10, wherein each of the first and second flexible abrasive discs is characterized as a double-sided abrasive disc having first and second abrasive layers on opposing sides of an intermediary backing layer.
16. The sharpener of claim 15, wherein the intermediary backing layer is formed of a selected one of cloth, paper or foam rubber.
17. The sharpener of claim 10, further comprising a magnet disposed within the housing adjacent a selected one of the first or second rotatable flexible abrasive discs to magnetically retain swarf responsive to a primary sharpening operation.
18. The sharpener of claim 10, wherein the manual sharpening module is configured to be removably attachable to the housing via sliding engagement of a first retention member on a main body portion of the manual sharpening module with a second retention member of the housing.
19. The sharpener of claim 10, wherein the manual sharpening module is characterized as a first manual sharpening module and the opposing first and second guide surfaces of the first manual sharpening module extend at a first selected guide angle, wherein the sharpener further comprises a second manual sharpening module having a second manual honing element in a second honing stage and opposing third and fourth guide surfaces which extend at a different, second selected guide angle, wherein each of the first and second manual sharpening modules can be separately installed between the first and second powered sharpening stages to provide different sharpening angles to the cutting tool against the respective first and second flexible abrasive discs.
20. A method for sharpening a cutting tool having opposing first and second sides that converge to an intervening cutting edge, the method comprising:
- inserting the cutting tool into a first powered sharpening stage of a powered sharpener to perform a primary sharpening operation upon the cutting edge, the powered sharpener having a housing which encloses an electric motor configured to rotate a first flexible abrasive disc in a selected rotational direction, and a removably attachable manual sharpening module having a main body with a powered stage guide surface and an interior manual sharpening element, the powered stage guide surface supporting the second side of the cutting tool during contacting engagement of the first side of the cutting tool against the first flexible abrasive disc; and
- drawing the cutting tool through an elongated slot of the manual sharpening module to draw the cutting tool against the manual sharpening element to perform a secondary sharpening operation upon the cutting edge.
21. The method of claim 20, further comprising removing the manual sharpening module from the housing of the powered sharpener after the inserting step and prior to the drawing step.
22. The method of claim 20, wherein the sharpener further comprises a second flexible abrasive disc mounted to the central shaft within the housing to provide a second powered sharpening stage, and wherein the method further comprises subsequently inserting the cutting tool into the second powered sharpening stage to perform a second primary sharpening operation upon the cutting edge, the manual sharpening module having a second powered stage guide surface which supports the first side of the cutting tool during contacting engagement of the second side of the cutting tool against the second flexible abrasive disc.
23. The method of claim 22, wherein the manual sharpening module is characterized as a first removable manual sharpening module that can be removably affixed to the housing, wherein the first and second powered stage guide surfaces of the first removable manual sharpening module extend at a first selected angle, and wherein the method further comprises removing the first removable manual sharpening module from the housing and installing a second removable manual sharpening module to the housing between the first and second powered sharpening stages, the second removable manual sharpening module having a second manual sharpening element in a second elongated slot and opposing third and fourth powered stage guide surfaces that extend at a different, second selected angle to form respective portions of the first and second powered sharpening stages.
24. The method of claim 20, further comprising using a magnet disposed within the housing adjacent the first flexible abrasive disc to magnetically retain swarf generated during the primary sharpening operation.
Type: Application
Filed: May 29, 2020
Publication Date: Dec 3, 2020
Inventor: Daniel T. Dovel (Shady Cove, OR)
Application Number: 16/887,913