Patent Application
20200368877
The present invention relates to a device for sharpening and honing a cutting edge, for example of a knife, that became dulled or had its edge rolled from normal use.
Sharpening devices are known and generally include a housing configured to define a guiding slot through which a cutting edge, for example of a knife, is drawn so that an edge contacts sharpening structures located within, or in association with, the guiding slot of the housing. The guiding slot provides general guidance to the user as to the appropriate orientation of the knife edge during sharpening.
The presence of such a guide slot—which needs to be wider than that of the knife blade—provides the user with guidance for a general orientation for sharpening, and is sufficiently deep so that the sharpening structures contact the cutting edge to provide a specific cutting angle.
Conventional knife sharpeners have biasing structures, such as crossed honing or sharpening elements, that contact the knife during the sharpening process to provide their own sharpening, and to provide visual and tactile guidance to the user during sharpening. Such devices provide spring biasing of the crossed elements by the use of either separate leaf springs abutting the crossed sharpening elements, or by attaching ends of each of two or more sharpening elements to the housing to provide the spring biasing.
The conventional manner of biasing the crossed sharpening elements has the disadvantage of requiring alignment of more than one sharpening rod, each being separately attached to, and biased in relation to, the guide slot in the housing. The separate biasing spring action must be coordinated between the two separate elements to provide for symmetrical sharpening guidance, which requires high precision coordination and dimensioning between the two sharpening elements, increasing production costs and making accuracy of construction more difficult. Also, because the two separate sharpening elements are attached individually to the housing, there are two points of possible failure, i.e., at each of the connection points with the housing.
Conventional crossed alignment and/or sharpening elements are asymmetrically arranged, i.e., the crossing elements are arranged to the outside of one face of the housing of the sharpener. Such an arrangement has several disadvantages. One is that the user must push draw the blade through the crossing elements in the direction of the housing that is behind the crossing elements. Because of this, if a pulling sharpening stroke desired, the sharpening unit must be properly oriented. Another disadvantage is that the crossing elements are exposed to being subject to impact, i.e., during storage in a drawer, which can result in misalignment of the crossing elements.
Thus, there is a need for a sharpening device that provides tactile and visual guidance to a person sharpening the knife, is less subject to mechanical failure or impact-related misalignment, and at the same time provides a device that is easier to manufacture with high precision.
It is therefore an object of the present invention to provide an improved sharpening device that is configured to sharpen and restore cutting edges, such as knives, that have been dulled through use.
According to a first aspect of the invention, a sharpener for sharpening a cutting edge of a cutting tool includes: a housing extending in an upright plane having an elongated vertically extending slot therein, and an anchor region; a spring biased sharpening element having a pair of arms, the sharpening element being arranged within the housing and secured to the housing at the anchor region below the vertically extending slot to provide a pivot point for the arms, the sharpening element having: a coil spring portion, arranged at the pivot point, and the pair of arms being integrally formed with the coil spring portion, each arm comprising first and second elongated sharpening portions, respectively, extending from respective ends of the coil spring portion, the coil spring portion and the first and second elongated sharpening portions being spring biased in relation to one another to maintain a crossed relation within housing, each elongated sharpening portion being swingable downwardly in crossed relation about the pivot point in a plane adjacent and parallel the plane of the housing, such that a crossing point of the first and second elongated sharpening portions remains within the slot of the housing. Each of the first and second elongated sharpening portions has an upper and lower part and a curved intermediate part extending downwardly from its upper part and relative to the pivot point, and the spring biasing of the sharpening element applies a force sufficient to urge each of the sharpening portions to, as the elongated cutting tool is drawn downwardly through and outwardly away from the slot, maintain its crossed relationship with the other by pivoting toward the other to thereby provide contact sharpening surfaces of each sharpening portion to respective sides of the cutting edge of the elongated cutting tool.
In another aspect, the sharpening elements are curved sufficiently so as to provide a substantially uniform angle of contact between cutting edge surfaces of the cutting tool and sharpening contacts of the sharpening elements as the cutting tool is moved downwardly and outwardly through the slot of the housing.
In another aspect, the sharpener further includes a mounting base affixed to a bottom of the housing.
In another aspect, the mounting base is affixed to the housing using a press fit connection.
In another aspect, the housing has one or more ports, and the mounting base has one or more spring arms each having a tab at an end portion thereof, the press fit connection being provided by engagement of respective ones of the one or more tabs with a respective ones of the ports of the housing.
In another aspect, each of the first and second elongated sharpening portions are made of metal and have an abrasive surface formed thereon.
In another aspect, the abrasive surface comprises a diamond electroplating.
In another aspect, each of the first and second elongated sharpening portions are made of steel and configured as a blade honing surface.
In another aspect, the sharpening portions terminate, at a top of the sharpener, in respective arcuate vertical end portions.
In another aspect, the sharpener further includes first and second spring pivots configured to engage with one another and with the coil spring portion.
In another aspect, the sharpener further includes a spring pivot bolt and spring pivot nut configured to be threadingly engagable with one another to securely mount the engaged combination of the coil spring portion and the first and second spring pivots to the housing at the anchor region.
In another aspect, the housing further includes a pivot hole located at the pivot point, the spring pivot bolt passing through the pivot hole when threadingly engaging the spring pivot nut.
In another aspect, the sharpener further includes a keying engagement between the housing and the first and second spring pivots.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
As best seen in the sectional views of
Preferably, at least at the elongated sharpening portions 12a and 12b, the spring biased sharpening element 8 comprises an abrasive surface, such as a surface having diamond electroplating, using, for example, 5-10 micron particles. Such a surface would be able to shape the cutting edge, performing true sharpening by removal of metal from the cutting edge until it is sharp. The use of alternative materials will be readily apparent to those of ordinary skill.
The spring can also be made of a steel surface that is relatively smooth, like that of a chef's honing steel. If the first and second elongated sharpening portions 12a and 12b are provided in this manner, then using the sharpener 1 would reshape, i.e., hone, the edge without removing material from the edge.
As will be discussed below, the sharpener 1 may include more than one slot, one having first and second elongated sharpening portions 12a and 12b with an abrasive surface for true sharpening, and another having first and second elongated sharpening portions 12a and 12b with a surface similar to that of a chef's steel, for honing the cutting edge. As is known to those of skill in the art, both sharpening and honing results in a blade with an improved cutting ability. Hereinafter, reference to the word “sharpen” or “sharpening” will be used mean either true sharpening or honing of the cutting edge.
Alternatively, the sharpener may provide the ability to readily replace a spring biased sharpening element 8 with the above-described abrasive surface, for a spring biased sharpening element 8 with the above-described honing surface.
The coil spring portion 10 and the first and second elongated sharpening portions 12a, 12b, are spring biased in relation to one another to maintain the first and second elongated sharpening portions 12a, 12b in a crossed configuration, with each elongated sharpening portion being swingable downwardly in crossed relation about the pivot point 14 in a plane adjacent and parallel to the plane of the housing 2.
The spring biasing of the sharpening element 8 applies a force sufficient to urge each of the sharpening portions 12a, 12b, as the elongated cutting tool is drawn downwardly through and outwardly away from the slot 4, to maintain its crossed relationship with the other by pivoting toward the other to thereby provide contact sharpening surfaces of each sharpening portion to respective sides of the cutting edge of the elongated cutting tool.
As can be seen, for example, in
This press-fit feature is facilitated by the provision in the mounting base 18 of plastic leaf spring arms 19 extending upwardly at two outer edges. The tab 20 extends outwardly at the top end of each leaf spring arm 19. During insertion of the mounting base 18 into the opening at the bottom of the housing, the arms 19 will be inwardly compressed by the housing walls, but, due to their resilient spring force characteristics, the arms 19 will maintain an outward biasing force. Upon reaching the height at which the tab 20 is level with the port 22 of the housing, the outward biasing force of the arms 19 causes the snapping in of the tab 20 into the port 22.
To remove the mounting base 18, for example for cleaning the sharpener 1 or replacing the spring biased sharpening element 8 due to wear, the tabs 20 may be pressed inwardly by the user while the user pulls down on the bottom of the mounting base, allowing the arms 19 to slide easily downwardly along the inner surface of the housing 2 until the arms 19 are free from the housing 2.
Spring pivot bolt 25 and spring pivot nut 26 are configured to be threadingly engagable with one another to securely mount the coil spring portion 10 and the spring pivots 24a, 24b to the housing. At least one of the spring pivots includes a female keying 116 that engages, upon assembly of the sharpener, with a male keying 115 of the housing. As can be seen from the partial exploded view of
Returning to
A passing through of the knife blade 30 consists of pushing the knife blade 30 down, by grasping a knife handle. The biasing of the spring biased sharpening element 8 will continually provide an urging force to return to the position of
Thus, as shown in
The biasing of the sharpening portions 12a, 12b and the coil spring portion 10 provides a force continually urging the sharpening portions 12a, 12b back towards the position of
An upwardly directed spring force is also provided to the bottom of the knife to urge it upwardly, preventing too rapid a downward motion, and making it less likely for the knife to bottom out in the sharpener.
Also, the sharpening portions 12a, 12b terminate, at the top of the sharpener 1, in respective arcuate vertical end portions 13a and 13b, respectively. The arcuate shape of these vertical end portions allow the top part of the spring biased sharpening element 8 to contact the inner side walls of the housing 2 at the lowermost point of the sharpening process, for example, as illustrated in
As should be understood, the provision of the spring biased sharpening element 8 within the housing 2, allows for symmetrical use of the sharpener 1. That is, during sharpening the blade of the knife can be drawn toward, or pushed away from, the user, without the need to orient the sharpener front-to-back, or back-to-front with respect to the user. Further, this arrangement prevents impact-related misalignment of the sharpening portions of the spring biased sharpening element 8 because the crossed sharpening portions are protected via positioning within the housing.
Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
