HK1089997B - Precision means for sharpening and creation of microblades along cutting edges - Google Patents

Description

Precision apparatus for sharpening and making microblades along a cutting edge

Technical Field

The present invention relates to a precision forming apparatus for making micro-blades along the edge of a cutting blade.

Background

To make ultra-sharp edges, a number of abrasive based sharpening devices have been described in their patents by many inventors. Such a blade is ideal for a variety of applications where the sharpest blade is required. Examples of such applications include razor blades, scalpels, and microtome blades for optically cutting ultra-thin slices of hard, non-fibrous materials. The cross-section of the edge suitable for this application shows that the facets meet at a very precise point or boundary, the width of which is less than a few microns, and the width of the edge used in ultramicrotomes is typically as small as 50 angstroms. Typically, for such precision slicing, the edge seen in a straight line profile is generally very straight and free of defects that are larger in size than the thickness of the edge.

However, there are many applications involving relatively softer fibrous materials, such as meat, fibrous muscle and fibrous vegetables, where small imperfections along the edge profile and across the edge facet boundaries can make cutting of such materials more convenient.

Disclosure of Invention

A precision forming apparatus for forming microdefects of controlled size and number along the edge of a blade for cutting such soft fibrous materials is disclosed. There are a number of serrated blades sold with purposely made and large mechanical serrations machined along the blade edge for cutting similar materials, particularly those with hard-tipped properties, where cutting is improved by the saw-like action of the blade. Such serrations, if large, can result in visually realistic tearing and chipping of the cut object.

The present application describes highly sophisticated apparatus and equipment that first presents a controllable method for reproducibly preparing edges with high geometric precision and with microblades at the boundaries of the edge facet and along the edge profile. Such defects can range in size from fractions of a micron up to over 100 microns. Defects of this size may be used as microblades, particularly if the microblades are substantially limited to a point within the geometry of the facet and the geometric extent of the original facet at which they would otherwise intersect to form an edge of approximately less than 20 microns in thickness.

Blade manufacturers have for several generations offered various elongated steel bars (often referred to as "steel members") for aligning the blade edges. These have proven to be particularly difficult or impossible to use for the general public because the user is unable to manually control the angle of contact with the edge facet, the orientation of the blade, or the pressure exerted by the steel member on the blade edge. Because few people do so, the use of tools for improving the cutting ability of the blade will already be very limited if anyone has the skill required to move the blade at a consistent angle and bar pressure repeatedly in one stroke. From a practical point of view, most people are warned of the potential danger of seriously cutting themselves while manually swinging the sharp blade against the steel bar. Thus, the advantages expected to be obtained by the device have not actually been obtained by the average cook or the average public.

The use of manual steel bars is not as scientific as it is, but rather, as skilled, lacking any scientific basis or understanding. For example, it is said that a manual steel bar "eliminates micro-gaps on the blade surface and rearranges molecules in the cutting edge". It has also been said that "best magnetization of the steel helps to pull the molecules into realignment" or "whenever sharpened, the alignment of the molecules in the blade is strengthened, … and the process removes little actual metal from the blade". Others have reviewed the use of steel to "realign and smooth the edge of the blade".

It is clear to both scientifically and physically founded persons that the magnetic forces involved in commercial sharpening rods are not capable of exerting any influence at all on the atomic level structure in the steel and even of altering the physical structure of any burr associated with the edge.

A number of manual bar type sharpening devices have been described in published U.S. patents, including:

U.S. patent No.5,046,385 to IVo Cozzini, No. 76/89.2, 9/10, 1991; U.S. patent No.2,461,690 to k.k.leong, classification No. 51-214; U.S. patent No.4,799,335 to silvero r.battachi, 24/6/1989, classification No. 51/102; U.S. patent No.4,197,677 to Louis n.graves, 4/15/1980, classification No. 51/214; U.S. patent No.4,094,106 to Thomas d.harris at 13/6/1978, classification No. 51/214; U.S. patent No.4,090,418 to Shigyoshi Ishida, 1978, 23, classification No. 76/84; U.S. patent No.5,163,251, classification No. 51/214, issued to David Lee on 17.11.1992. For a variety of individual reasons, none of the prior art devices have proven to be practical devices that can repeatably modify physical structures along a cutting edge. None of the patents include means for determining the angular orientation of the edge facet relative to the hardened surface of the steel bar or other material with sufficient pointing accuracy or consistency to achieve the effects described in this application. Efforts have been made in the prior art to provide a guide for the blade, but the devices used are not angularly consistent or precise because of variations in blade geometry, blade height, blade thickness, etc., or because the precision of the device is inherently poor and the impacts may vary.

Typically, in the prior art, the angle of the facet provided relative to the hardened surface is entirely determined by the skill of the operator. Thus, those inventors have found that these designs lack the precision and repeatability necessary to form the optimum and consistent microblade structure along the cutting edge of the blade, regardless of the geometry and dimensions of the blade geometry or the skill of the user of such devices.

The edge conditioning apparatus disclosed herein relies, among other things, on a highly accurate angular reference of the blade edge based on the most repeatable feature of the blade, i.e., the plane defined by the large face of the blade, which can be held in precise position on a flat physical plane to ensure the required angular accuracy, independent of variations in other physical features of the blade.

The present invention is based on the following findings: a surprising series of things occurs along the edge if the straight edge of a sharpened blade is pressed against or dragged along a hardened surface (preferably of hardness greater than rockwell C-60, but preferably certainly harder than the blade edge) in the general direction of the linear axis of the edge in a carefully controlled manner so that the face of the edge facet adjacent the hardened surface is at an angle, preferably only a few degrees, against the surface in line with the face of the hardened surface with the appropriate force. Contrary to the generally believed view, the burr formed in the previous sharpening step does not straighten but is first deformed, removed, split or pressed against one side of the edge and eventually chipped as tiny fragments along the edge break off, leaving a microscopically serrated edge. The burr may be removed, pressed against the first facet or it may be moved to the opposite side of the edge and pressed against the facet. The physical action of moving the burr fragments from one side of the edge to the other or pressing them against the edge creates severe cracking and defects along the edge structure, ranging in size from a few thousandths of an inch to almost a micron. As one then continues to strike the blade edge facet repeatedly across the appropriate hardened surface at the same consistent small relative angle, a micro facet is formed at the boundary of the larger facet and small micro-serrations are formed. Studies of this process have shown that if the angular relationship between the hardened surface and the contacting edge facet is closely and consistently controlled and the applied pressure is controlled, the average size and number of microstructures along a given blade edge are surprisingly completely repeatable each time the process is repeated. Because of the very small size of the microstructures, the blade edge so formed is razor sharp, and is a good cutting edge for fibrous materials. As will be described later, the characteristics of the edge structure can be modified by changing the angular relationship, but consistent, predictable results are critically dependent on precise control of the angle along the edge at each impact.

As previously mentioned, the accuracy of the physical geometry along the cutting edge of the blade and the presence of microstructures along the edge can play a very important role in the cutting ability of the blade depending on the properties of the material being cut. Near perfect geometry of the edge formed by the facets supporting the edge is important if it is desired to slice or more precisely control the direction or path of travel of the edge as it penetrates the material being cut. In order to cut ultra-thin slices of stronger and harder materials, even more geometrically perfect edges are required. Also, for cutting softer fibrous materials, the perfection of the geometry is very important if it is desired to cut very thin slices, but the presence of a series of micro-blades or micro-defects along the edge can be an additional advantage of cutting soft fibrous materials that may otherwise deform slightly under the cutting pressure and thus provide resistance to the more finished edge with smoother geometry being applied. For these reasons, the most common cutting edge for soft materials is one with controlled defects or microblades along the edge rather than an edge with a high degree of geometric perfection. Without geometric perfection, it is more difficult to cut thin sections. Without edge defects, it is more difficult to cut the fibrous material. For these reasons, close control of all factors affecting the edge conditioning step is important in order to optimize the final edge profile and the formation of defects or microblades along the edge.

Drawings

Fig. 1 to 9 illustrate various knife edges;

figures 10 to 12 illustrate sharpening of the blade;

figures 13 to 20 show various devices that may be used to sharpen and condition the edge in accordance with the present invention;

FIGS. 21 and 22 show in detail the angular relationship of facet and hard material required to make this optimum edge configuration; and is

Fig. 23 to 24 show the application of the invention with a clamping blade and precision means to move hard objects across or along the edge of the blade.

Detailed Description

Fig. 1 shows a conventional double-facet insert 1 with two faces 3 terminating in facets 2, each facet being formed at an angle a (fig. 2) relative to the insert face 3. Typically, each facet is sharpened at an angle a and intersects the edge. The nature of the edge itself is determined by the method used to sharpen the facet, but if the facet is ground using conventional methods, a burr 4 will form along the edge, as shown in figures 3 and 4, figure 4 being an enlarged view of the circular area of the edge itself (figure 3). Figure 4 is a view of a freshly sharpened edge showing a series of individual burr structures bent nearly perpendicular to the center line of the two facets. Figure 5 shows how facets 2 and residual burr 4 along the same edge in figure 4 may appear after the facets have been forced into frictional contact multiple times at a consistent and precisely controlled angle with respect to the plane of the hardened surface and moved in a direction nominally aligned with the linear edge of the blade. Figure 6 shows the edge structure after (a) its back facet has been repeatedly pressed at the same controlled angle against the hardened surface and (b) the front facet has also been pressed against the hardened surface. The nature of these edge deformations will of course depend on the pressure exerted on the edge against the hardened surface, the relative angle between the plane of the facet and the plane of the hardened surface and the number of impacts against the hardened surface. Most of the initial burr structure will have been removed at this point and the desired microstructure begins to develop along the edge.

By repeating the step of alternately pressing one side and then the other side of the edge against the hardened surface at a precisely controlled angle, approximately 10 to 20 times, the burr is disconnected from the facet boundaries and the remaining pieces of the burr are shed, leaving an edge structure similar to that shown in figure 7. Additional pressing of the resulting edge structure against the hardened surface at a precisely controlled angle leaves a very regular fine microteeth structure along the edge as shown. As will be described later, success with this technique is only possible if the angle of the plane of the contact facet remains consistent at the same precise angle relative to the plane of the hardened surface at each impact at the point of contact.

Thus, the microteeth formed along the blade edge can improve the efficiency of cutting a wide range of materials, including fibrous foods.

The process of slidingly pressing the edge against the surface of the hardened material can be repeated hundreds of times before the blade facet needs to be resharpened (re-angled) as it moves in a direction generally coincident with the edge axis and at a consistent and precisely controlled angle between the plane of the hardened material surface and the plane of the facet in each stroke. This is particularly true if the angle between the facet and the hardened surface is small, for example in the range of 3 to 10 degrees. Repeated contact causes the remaining edge structure to harden and thus repeatedly break, leaving hyperfine microteeth along the edge. It is important to understand that the means and precision of positioning must be sufficiently precise that the contact area along the edge facet is strictly limited to the lower portion of the facet very close to the edge. However, as this rubbing process is repeated hundreds or thousands of times, repeated breaks along the edge will remove one row of initial microteeth along the edge and another new row of replacement microteeth is formed along the remaining edge structure. This process must be precisely controlled by using a bevel guide and preferably by means of a device that firmly holds the blade face against the guide, otherwise a poorly localized contact impact along the edge can eliminate most of the microstructure and result in less efficient edge cutting capability. As this process repeats, trace amounts of metal will be removed along the edge by repeated fracture along the edge and micro-shearing along the lower portion of the facet surface. As the edge itself repeatedly stress hardens, fractures and peels, the width of the blade facet (measured perpendicular to the edge) diminishes, but at the same time, the actual line or area of contact between, for example, the cylindrical hardened surface and the facet surface slowly lengthens, requiring a slightly greater pressure to be applied between the facet and the hardened surface in order to remove a trace amount of metal from the facet and maintain consistent and proper contact with the edge and its fractured microstructure. At this point, it may be more time and labor efficient for the user to judge that the edge needs to be resharpened in order to provide a more favorable relative angle between the lower portion of the facet and the surface of the hardened material. The device is described in more detail in the latter part.

The subtle nature and precision of the edge conditioning process is clear by the recognition that the operation is initially limited to the lower 1% to 10% of the facet near the edge. The facets on relatively new inserts are typically only about 0.025 "(0.6 mm) wide. This means that the initial contact area with the hardened surface is limited to about 0.002 "(0.05 mm) of the land area of the edge itself. As the facet is repeatedly pressed hundreds of times across a corresponding area on the hardened surface, the contact area of the facet does increase slightly due to the abrasive action near the edge, and this contact area will eventually extend upwardly on the facet toward the shoulder where the facet meets the blade surface. As the process continues, the force applied to the blade is distributed over a larger facet area and the level of stress applied at the point closest to the edge is reduced. However, as long as the blade is used for cutting, lateral distortion of the microteeth occurs, which increases the lateral stress on these teeth during subsequent re-finishing and thereby facilitates continuous removal and re-creation of microteeth along the stressed and stress hardened edge.

The high precision nature of this novel finishing process is even clearer by recognizing that the amount of metal removed along the edge of a 10 inch blade as a result of one thousand controlled impacts along the edge is very small and only about 5 to 10 milligrams of steel.

It is important to recognize that the controlled repetitive motion described herein to create a microstructure along the edge is fundamentally different from conventional sharpeners which use a planing action to quickly remove the entire facet in only one or a few impacts and thereby create a new facet and a new edge. Conventional planing devices are similar to conventional sharpening devices in that they are designed to create a new edge by removing the old facet in its entirety and replacing it with a new facet created at an angle that is typically poorly positioned. The class of prior art planing sharpeners includes those that use a sharp edge of a hard material, such as silicon carbide or tungsten carbide, to remove a large amount of metal at an uncontrolled angle in one stroke and completely replace the entire facet with very few strokes. These planing devices may also be provided with wheels or corners made of hard metal or ceramic with intersecting sharp edges. They do not contain means for precise angular control and are therefore unsuitable and problematic for precision edge finishing of the type described herein.

The inventors have found that this new micro-manipulation device for forming microteeth along the cutting edge must be precisely controlled if the result is to be optimized. For best results, in order to control the rate at which the burr edge transitions to the microteeth edge 6 of fig. 7, the contact angle B (fig. 9) between the face 2 of the edge facet and the face 5 of the hardened surface at the point or line of contact must be repeatable and constant with great precision. The best cutting edge is generally obtained when all the initial burrs are removed and the microteeth structure is formed.

The edge with the pronounced burr shown in fig. 3 and 4 does not cut very well. The edge cuts significantly better when the burr structure is removed and the microteeth is formed. The blade as shown in fig. 6 will cut well but will cut better when further modified to the blade configuration of fig. 7. It is clear that if the thickness W of the edge boundary becomes too large (fig. 8), the advantage of having microteeth will be somewhat reduced. There is therefore a clear advantage in forming a cutting edge with microteeth, and it would be better to achieve this in a way that minimizes the effective thickness of the cutting edge at its boundaries.

The inventors have been able to demonstrate that if the angle B (figure 9) between the plane of the facet 2 and the plane of the hardened surface 5 of hard material at the point of contact remains less than 5 deg., for these facets, as they move repeatedly along the hardened surface 5 in an alternating facet manner, the burr will wear away relatively quickly and microteeth will form in small amounts without increasing the effective edge thickness. A blade thickness of 5 microns is readily achieved. However, if the angle B is much greater than 5 degrees, the frangible edge will have more bending on each impact, which will prematurely dislodge the microteeth and will disadvantageously increase the effective thickness of the edge as the microteeth breaks. If a larger angle is also used, the hardened surface will rub more under the edge, tending to widen and eliminate the microstructure, thereby reducing the structure and reducing its cutting effectiveness.

If an attempt is made to condition a freshly sharpened faceted edge by manually moving the blade and impacting its edge against a hardened surface without precisely controlling the contact angle between the plane of the facet and the hardened surface, this will quickly compromise or destroy the quality of the microstructure formed along the edge and produce an edge with far less than optimal cutting capabilities. Furthermore, repeated contact at different angles and from different directions in successive impacts may prevent clean formation of the microstructure and may not result in an optimal edge. Consequently, the edge must be resharpened more frequently and the life of the blade is shortened. To avoid (a) impacting the blade at an angle less than the facet angle a (fig. 9) so that the edge itself does not contact the hardened surface or (b) pressing the edge at a very large angle or with excessive force, which would widen the edge and prevent effective removal of burrs and creation of an optimal microstructure along the edge, it is necessary to use the precise bevel angle guides of the blade at all times during each impact. This novel method of creating microstructures along the edge can avoid the frequent resharpening that results from conventional methods, a fact that is important not only for extending the life of the blade, but is also a big advantage for butcher or users who do not have to interrupt their cutting operation frequently in order to resharpen the blade.

Therefore, controlling the angle B (fig. 9) is quite critical. It is clear that if the angle a is accurately controlled in the previous sharpening step, it is possible to ensure accurate control of the angle B between the facet and the hardened surface 5 in a suitable way.

It is important to emphasize the novelty and value of providing a precision sharpening device that sharpens the edge facet at a very precise angle a relative to the plane of the blade surface and a conditioning device that conditions the sharpened edge by pressing the lower portion of the facet so formed at a very precise and sustained angle B (optimally only a few degrees greater than angle a) against the plane of the hardened surface in a single device. This unique combination ensures the angular control required to optimize the breaking of the edge structure and the formation of the highly regular micro-sawtooth structure along the edge. By using these two critical steps in the same device, a particularly important and necessary angular relationship can be ensured.

Figure 10 shows a precision blade sharpening apparatus sharpening the blade with sufficient precision before the blade passes through the precision edge conditioning apparatus. It comprises two precision angle guide surfaces 8 and 8a set at an angle a relative to the plane 11 of the sharpening grit layer on the surface of a rotating disk whose surface is shaped as a section, for example, of a truncated cone. A blade 1 with its face 3 positioned against the guide surface 8 will be sharpened by this device to form a facet 2 whose plane will be precisely formed at an angle a relative to the blade face 3. Abrasive disks (abrasive coated disks) 9 and 9a are shown here rotating about their mounting shafts 10 driven by a motor (not shown). As the discs move from their rest position, determined by the stop 12, the discs are free to move slidingly on the shaft 10 against the spring 14 on the shaft 10. After the facet is formed on the first side of the blade as shown, the blade can be moved onto the guide surface 8a, where a second facet can be formed by a second grinding wheel disc 9a at an angle a relative to the opposite guide face 3 of the blade. This type of sharpening device is described in more detail in the inventor's earlier us patent.

Figure 11 shows a precision edge conditioning station suitable for use with a precision sharpening station. Shown is a cross-section of a precision elongate blade guide having guide surfaces 7 and 7a and a hardened member 13. The face 3 of the blade 1 shown rests on an elongate guide surface 7 which is accurately positioned at an angle C relative to the contact surface 5 of the hardened member 13. If the blade 1 is first sharpened in the precision sharpening apparatus of figure 10, its facet 2 will be precisely at angle a relative to the elongated surface of the guide surface 7. As a result, the plane of the facet 2 is positioned at an angle B (angle C-angle a) precisely with respect to the hardened surface 5 (fig. 11). It is therefore clear that by independently and accurately controlling the angle a of the sharpening process in fig. 10 and the angle C of the edge conditioning process in fig. 11, the angle B of the edge itself during conditioning can be accurately controlled. The angle in each sharpening and edge conditioning step must be independently and precisely controlled in order to create the optimum microstructure along the blade edge. To obtain the highest accuracy, angle a and angle C will be formed using the same reference feature of the blade. For this purpose, the most reliable reference feature of the blade is its elongated large facet. By using the two large faces of the insert as references, respectively, the angle of the facet can be precisely shaped at the angle a. Also, by using the same plane as a reference in the edge conditioning step, the angle B between the thus formed facet and the plane of the edge conditioning hardened surface at the point of contact will be precisely controlled.

The guide surface described herein may be an extended flat surface or a series of two or more bars or rollers may be provided to form an extended plane against which the blade may rest when the blade edge is sharpened or finished by contact with a hardened surface. It is important that the hard surface has sufficient hardness, but the support structure below the surface does not have to have the same hardness.

Figure 12 simply illustrates the advantage of using one elongated guide surface 7 and the long face of the blade 3 as reference surfaces in order to position the edge facet 2 of the blade 1 at a precisely controlled angle relative to the plane of contact formed by the hardened surface member 13. The close contact of the elongated planar region 3 on the back side of the blade with the rigid planar surface 7 of sufficient length, width and area ensures precise control of the angular position of the blade and its facet with respect to the predetermined orientation of the hard contact surface 5 on the member 13. The greater the length and width of the guide surface, up to the blade size, the greater the accuracy of the angle control. To better ensure sufficient angular accuracy, the length of the guide surface is no less than 20% of the length of the blade, but is typically no less than about one inch. By controlling the angle between the facet and the hardened surface in this way, the angle will be very consistent and will not change due to characteristics such as blade thickness at the edge or blade width variation along the length of the blade. It is clear that the accuracy of the above-described angular control using an elongated plane, such as that shown in fig. 12, will be much higher than that obtained, for example, with a single circular guide bar angularly aligned onto a hardened surface to serve as a bevel guide adjacent the hardened member 13. Two bars may be provided at a common angular spacing to define a plane for guiding the blade, but a continuous surface across the entire length of the blade will be more accurate and more convenient. Random variations of only a few degrees in the alignment of the facet and hardened surface will significantly affect the quality of the microstructure along the edge of the insert. Precise angular control can of course be obtained by clamping the blade in a precise robotic arm, where the precision of the arm mechanism provides the required angular precision. However, such complex devices are not practical in a home or industrial kitchen or slaughter environment, and they represent an unnecessary complexity to obtain the required accuracy.

Figures 13 and 14 show a construction for a precision manual edge conditioner according to the principles described above. The hardened member 13 is nominally centrally mounted between elongate blade guides 17 in a physical structure 15 having a connecting handle 16, the handle 16 being conveniently held in one hand while the face of the blade 1 is alternately pulled along the surface of the guide 17 with the other hand. The length of the guide 17 is sufficient to ensure accurate alignment of the blade edge with the guide and the contact surface of the hardened member 13. The use of two hard members 13 is optional, but such use has the following advantages: in configuration 15, the edge conditioner can be conveniently used by either a right or left handed operator and has the advantage of two hardened members sharpening the blade more quickly and the advantage of being able to condition the entire length of the edge up to the hand guard or handle. Alternatively, only one rigid member 13 may be similarly located between the guides. The members 13 are sized and positioned as shown centrally between the guides so that the edge of the blade facet will contact one or both members as the blade is pulled along the elongated guide surface and pressed against the contact surface of the hardened member. The angle of the elongated blade guide may be selected so that the angle between the plane of the edge facet and the plane of the hardened surface is optimized for the blade whose edge is being finished. A mechanism such as that shown in figure 16a may be employed to allow adjustment of the angle of the guide so that the angle C (figures 11 and 16a) can be optimized for the particular angle of the edge facet being conditioned. Alternatively, as described above, a combination of a precision edge sharpener (either manual or motorized) and a precision manual edge conditioner thus provides control of angles a and C in one device and ensures the best results of the edge conditioning step.

The rigid member 13 may be cylindrical, oval, rectangular, or any shape. Preferably, the member has a hardness greater than the blade being sharpened. The radius of the surface at the line or point of contact may be designed to optimize the pressure exerted on the blade edge when the blade edge is forced into contact with the surface. The effective radius at the contact line or contact area may be the result of a large curvature of the hardened member or the result of microstructures, such as grooves and ribs, at that point. For best results, such grooves, ribs or score lines along the surface should be generally perpendicular to the edge line being finished and, in any event, it is preferred that the arrangement of grooves or score lines be aligned across the edge line. The invention may be applied to such ribs having their axes at an angle other than perpendicular, including angling the ribbed surface or spiraling the rib to form alternating angles of attack.

In creating the optimum edge configuration by the novel, precise means described herein, the hardened contact surface 13 will initially contact the facet only at the end of the facet 2 adjacent the edge (fig. 21). As the burr is removed, the hardened surface will also remove trace metal adjacent the edge and the lowermost portion of the facet will begin to re-angle to an angle closer to the angle of the hardened plane after multiple impacts. Thus, a line and larger contact area 44 (FIG. 22) is created between the lower portion of the facet and the contact surface of the hardened member. This increased contact area 44 (fig. 22) created by the multiple repeated impacts of the facet against the hardened surface is important to stabilize the localized pressure on the forming edge structure and thereby reduce the likelihood of premature micro-tooth loss during subsequent edge reconditioning. The device relies on a highly accurate and consistent angular relationship between the facet and hardened surface, which reduces the chance of the hardened surface striking under the edge and knocking off the microteeth by that striking rather than by the desired repeated wear along the facet side and the resulting stress hardening and fracture process.

It has been found that localized axial ribs along the surface of the hardened member is a convenient way to create the appropriate localized stress levels on the facet and edge without damaging the microteeth being formed. However, it is preferred that the ribs each be rounded and not terminate in an ultra sharp edge that can remove too much metal and thus tear the microteeth. The level of force must be sufficient to stress the microteeth and create fractures beneath the root of the microteeth and allow their removal and replacement after the cutting edges have dulled for use. In order for such a rib to not remove a significant amount of metal along part of the edge facet, the depth of such a rib must also be controlled.

The hardened member 13 (fig. 13) may be rigidly fixed to the structure 15 or alternatively, the hardened member may be mounted on a structural member such that it may move slightly against the restraining force when the edge facet is pressed into contact with the member. The restraining force may be provided by a linear or non-linear elastic material or similar means. It is possible to design the device to allow the user to manually adjust or select the amount of restraining force and the range of displacement. Fig. 15 and 16 illustrate one of many possible configurations that employ the concept of a restraining force. The hard member 13 shown in fig. 15 and 16 may be, for example, a cylinder or tube with a hard surface, or a hollow body rotatable on a threaded rod 18 and internally threaded, the rod 18 extending into a support 19 bored to receive the non-threaded portion of the rod 18, and the rod 18 in turn being grooved to receive an elastic O-ring 20 that supports and physically centers the rod 18 in the bore of the support 19. If this or a similar structure is installed in the device of fig. 13 and 14, as the blade 1 (fig. 13 and 14) is inserted along the elongated guide 17, the hardened member 13 will contact the blade edge facet 2 and move slightly angularly or laterally by applying sufficient downward force to the blade 1, resulting in a lateral force being applied to the O-ring 20. To maintain the contact angle B preferably within 1 to 2 degrees of optimal value, the degree of compression of the O-ring and the resulting angular displacement of the hardened member 13 may be limited by physical stops or other means. By allowing the hardened member to move slightly in this manner under a controlled resistance pressure, it is possible to minimize the chance of excessive pressure being applied by an operator manually applying a force between the blade and the hardened member. Excessive force is detrimental to the progressive process of removing burrs and forming microstructures along the edge in an optimal manner. However, if it is desired to accelerate the rate of microteeth generation, more pressure can be applied to the blade, the angle B will increase slightly and the microteeth will be generated faster. It has been found that there is an optimum level of resistance and the apparatus provides a way to establish and maintain the optimum level. Typically, a resistance of between 1 and 3 pounds is optimal. The threaded connection of the hardened member to the support bar 18 allows the user to rotate and raise or lower the hardened member 13 in order to expose the new surface of the hardened member to the blade facet 2 when the surface of the hardened member becomes distorted, carries debris, or is excessively worn due to repeated contact with the blade facet. The threaded connection may be tight enough that the hardened member 13 does not rotate when the blade is rubbed on its contact surface. Alternatively, the threaded connection may be loose enough to rotate slowly due to friction and friction as the blade edge is pulled across the surface of the hardened member 13. Preferably, the hardened surface will perform little or no conventional abrasive action on the edge structure. If there is any abrasive action along the edge, it must be small enough not to significantly interfere with the slow process of deburring by non-abrasive methods or prematurely remove the fine microstructure formed along the blade edge. As will be described later, some advantages may be shown in some cases due to the very slight abrasive supplementary action along the edge that may slightly reduce the width of the microstructure, but this action must be particularly gentle and careful to not remove the microstructure being formed by the hardened member.

The arrangement of figures 13, 14, 15, 16 and 16a is but one example of a structure that can be used to achieve a precision edge conditioning process while maintaining tight control of the angle B (figure 11) between the plane of the facet 2 and the plane of the hardened member 13. The shape of the surface and the shape of the hardened member may vary widely to accommodate various alternative means of accurately guiding the blade and accurately determining the angle B between the surface of the hardened member 13 and the blade facet 2. It will be appreciated that various alternative restraining mechanisms may be used to position the hardened member and allow controlled movement of the hardened member but provide resistance to that movement, including wire springs and leaf springs. Various alternative means may be used to allow movement of the hardened members to expose new areas on the surface they may be used to condition the edge. A sharpener employing a precision sharpening station and edge conditioning apparatus as shown in figures 15 and 16 allows for precise control of angle B and formation of the edge with optimum conditioning as previously described.

As previously mentioned the surface of the hardened member may be embossed, scored or provided with a texture or pattern to be formed, with higher but controlled localized pressure and force being applied along the blade edge to assist in removing the burr structure and forming the microstructure, which would otherwise be necessary to apply greater manual force on the blade itself. Such a microstructure may be formed by a series of fine, hard, shallow ribs on the surface of the hardened member, for example, spaced 0.003 inch to 0.020 inch apart, where it is preferred that the axes of the ribs be perpendicular to the edge line but always aligned at a significant angle to the edge line when the edge contacts the hardened surface. Preferably, such ribs should be so shallow that they do not remove excess metal from the facet adjacent the microstructure being formed. However, in order to achieve an optimal microstructure, the plane of such ribs, defined by the plane of the contact surface, point or line adjacent the contact blade facet, must maintain an optimal angle B as described herein. The optimum size of such ribs is determined in part by the hardness of the blade material.

The possible geometries required for the hardened surfaces to form the edge microstructure described herein may include repeating geometric features having small radii on the order of thousandths of an inch. However, the finishing step described herein is not a conventional planing operation, which would typically remove, re-angle, or create a new facet regardless of the specific, desired microstructure along the edge itself, and it is important to understand this. The present invention can be said to be a precision operation that addresses the careful removal of burrs from blades that have previously been sharpened using conventional methods by urging the blade edge against the surface of a hardened material at a precisely controlled angle relative to the surface with sufficient pressure to progressively and significantly remove the burr, fracture the edge at the point of attachment of the burr, and create a relatively uniform microstructure along the edge. Planing the entire facet (or re-angling the entire facet) will work in reverse, as with a rough and aggressive sharpening, which will create a new facet and re-create a traditional burr along the edge, and leave the edge very rough and unfinished.

The present invention is a unique method for conditioning a traditionally sharpened edge so as to create an efficient microstructure along the edge while maintaining a relatively sharp edge defined by its geometric perfection.

The formation of this useful type of blade requires highly precise repetitive micro-operations. In addition to the need to accurately determine the angle between the plane of the facet and the surface of the hardened material at the point of contact, it is critical to ensure that the angle of attack is maintained each time the edge strikes along its entire length. The angle of attack must be maintained with a repetition accuracy that reduces approximately plus or minus 1 to 2 degrees. This precision of repetition is required to avoid serious damage to the microteeth or to alter the characteristics of the edge structure being formed along the edge. Furthermore, to avoid premature shedding of newly formed microteeth, the pressure exerted by the blade facet on the hardened surface must be optimized. The forces generated along the edges of the facets by the repeated sliding contacts smooth the sides of the microteeth, but compress and tension them in a manner to repeatedly fracture their support structure along the edge at a depth significantly below their apparent point of attachment. This repeated process ultimately results in the removal of the microteeth and their replacement with a new row of microteeth formed by repeated breakage of the supporting blade structure beneath each "tooth". The amount of force exerted on the microteeth in each impact is determined by the downward force exerted on the blade by the user. It is important to recognize that the localized forces on the microteeth can be very large because of the wedging effect at the blade edge between the elongated angled blade guide and the hardened surface. Thus, the force that must be applied by the user is relatively modest and, of course, less than would be directly applied without the blade guide. It is difficult to consistently apply this level of force to the blade edge by any manual, unguided impact procedure.

Generally, the hard material should not be an abrasive. The process removes the burr, forms microteeth along the edge, and grinds away trace metal from the facet adjacent the edge by a substantially non-abrasive process. The rate of metal removal by any abrasive is readily achieved in comparison to trace amounts of metal removed while forming and reforming aligned microteeth along the blade edge.

The edge conditioner shown in fig. 13 and 14 includes two hardened members 13 so that the device will be equally effective if used by either a right-handed or left-handed person. It is clear that this construction allows to refine the entire length of a conventional blade, in particular including the portion of the cutting edge close to the handle or hand guard. If there is only one such member 13 in a device having one elongated guide 17 for ensuring precise angular control, then it will not be possible for either the right-handed or left-handed person or both to comfortably condition the blade edge to the full length of the hand guard or blade handle. In order to condition the edge near the guard while providing an elongated guide for the blade surface, a hardened member must be located on one side of the conditioner so that the entire edge can contact it, up to the guard and the blade handle.

As previously mentioned, hard surfaces should not have an inherent tendency to wear. The surface should not be coated with conventional, more aggressive, large abrasive material particles such as diamond, carbide or oxide abrasive particles. When in the form of particles of suitable size, these materials often have particularly sharp edges that impart their aggressive abrasive properties. However, these materials are extremely hard and are essentially non-abrasive when prepared in a largely planar form and highly polished. The edge conditioning process disclosed herein relies on the precise application of bevel pressure by a hardened surface on the facet at its facet edge in order to cause the microstructure to repeatedly form and fracture along the edge at the boundary of the facet. The process of repeatedly rubbing the blade facet and edge structure against the hardened surface stress hardens the facet near the edge, fractures the edge below the edge line and deforms the metal immediately near the edge. The metal along the lower portion of the facet near the edge is deformed, abraded away by the localized contact pressure and microshear because of the small difference in the orientation angle of the plane of the hardened surface to the plane of the blade facet. Thus, the localized contact pressure slowly fractures the microteeth along the edge and slowly and selectively re-angles the lower portion of the facet to intimately contact the plane of the hardened surface. It is clear that if the difference in the positioning angles is too great, or if there is any real abrasive action at the edge, the microstructure will be abraded away and destroyed prematurely, otherwise it will be slowly formed and reformed. In order for the microstructure to have time to develop and prevent direct wear, the rate of facet deformation and metal removal near the edge must be minimized. The amount of wear that occurs along the lower portion of the facet due to the inherent roughness of the hardened surface in the range of a few microns appears to be acceptable. In order for such roughness not to cause excessive metal removal while forming an optimal microstructure, surface roughness (versus size of small repeating geometric features) greater than about 10 microns will be roughly the application limit in some cases with limitations on pressure and rate of microteeth generation. Therefore, it is important that the hard surface not have significant abrasive properties.

Because it is important to control the angle B between the plane of the sharpened facet along the edge and the surface at the point of contact with the hardened surface, it is important to control the angle a of the facet (figure 10) and the angle C in the conditioning operation (figure 11) as described above for optimum conditions so that the difference B (angle C-angle a) is closely controlled. Thus, it is now clear that there is a significant advantage to forming a single device 31 that includes the sharpening stage and the edge conditioning stage 26 and that each have precisely controlled angles a and C, respectively, as shown, for example, in fig. 17 and 18. The sharpening station can be manual or motorized, but in this example the sharpening station is motorized. The first (sharpening) station 25 of the apparatus has an elongated guide plane 23 and an abrasive surface each disposed at an angle a relative to the blade face. The guide planes 24 in the second (edge conditioning) station 26 are each disposed at an angle C relative to the contact surface of the hardened member 13. The first station (figure 17) is shown with a U-shaped guide spring 22 designed to hold the blade firmly against the elongated guide plane 23 as it is pulled along the elongated guide plane and into contact with the sharpening disks 9 and 9a (figures 10 and 18).

The U-shaped guide spring 22 which firmly holds the blade face against the guide plane 23 in fig. 17 is shown for the first station 25, but is omitted in the second station 26 merely for clarity. Such springs are described in U.S. patent nos. 5611726 and 6012971, the details of which are incorporated herein by reference. However, to ensure that the blade face 3 remains in intimate contact with the elongate guide plane, it is preferred that a similar blade guide spring 22 extends along the length of the guide in the second station 26. That in turn will ensure that the blade facet is oriented relative to the contact surface of the member 13.

The rigid member 13 is supported above a structure 19, which is located in front of the drive shaft 34 or is slotted to allow the shaft 34 to pass and rotate continuously, while the shaft 34 is supported at its ends by bearing means 35, which bearing means 35 in turn is supported by a structure 37 connected to the base 32. The structure 19 is also part of the base 31 or is a separate member connected to the base 31. The hardened member 13, which in this example is supported by a rod 18 and is threaded onto the rod 18, can move laterally when in contact with the blade cutting facet, the amount of movement being controlled by selecting the appropriate hardness and design of the O-ring 20. Alternatively, the member 13 may be rigidly mounted to the structure 19 so as not to move, but this option requires slightly more skill on the part of the user to avoid applying excessive force along the cutting edge.

The practice of the apparatus as shown in figures 17 and 18 demonstrates the significant improvement in forming the edge microstructure in a strictly uniform condition, where the angular difference B (C-a) is precisely controlled by a precisely elongated guide to be in the range of 3 to 5 °. The advantage of having both sharpening and edge conditioning operations in the same device is evident because each angle a and C is predetermined by the preset angle of the elongated guide. The sharpening process, which must be designed to form all facets at the desired angle a, can be accomplished by any conventional means known to those skilled in sharpening, including grinding and planing means. It is also noted that the use of diamond grit in the sharpening stage provides advantages for the rapid and accurate formation of a base facet with a significant burr. Diamond is the most efficient abrasive for sharpening and cleanly removing metals. Thus, diamond, regardless of its hardness, can form a very pronounced and well-defined burr along the edge of any metal without overheating. The process of creating the optimum microstructure along the blade edge relies on starting with a blade that is sufficiently sharpened and forms a good facet and then applying pressure by a small angular difference B alternately on one side of the edge and then the other until the residual burr is removed, leaving a microstructure along the edge. As this breaking process continues, it may be interrupted and the blade may be used to cut food or other objects, and then further refined to again further enhance the cutting ability of the blade structure. This reconditioning process can be interrupted and repeated multiple times until the reconditioning process becomes so slow that it is desirable to resharpen the edge and start with a newly formed facet. By maintaining a small angular difference B during this process, it is important to note that the edge can be reconditioned a number of times before needing to be resharpened at angle a to create a new precise facet.

The cutting ability of the blade edge depends on various factors, but most importantly the geometric perfection of the edge and the nature of all microstructures along the edge that contribute to the effectiveness of cutting certain materials, particularly fibrous materials as described herein. The manual and motorized devices described in this publication are designed to optimize and control the formation of the desired fine microstructure along the edge. In forming this microstructure, the burr remaining from the previous sharpening step is gradually removed until virtually all of the burr is removed, leaving the microstructure. As shown in fig. 8, when the burr is removed, the microstructure is generally formed as shown, but the edge may sometimes be wider at its boundary than if the facets 2 intersected at a point. This is because of the debris left along the edge or the destroyed microstructure resulting from the use of the blade. These fragments are usually small but it is also possible to reduce their size slightly without removing the microstructure being formed. It has been found that by using a finishing process in the form of a very slight polishing and sharpening action (non-aggressive) at an angle precisely set very close to angle C, it is possible to reduce the size of such chips along the edge during the edge finishing step without significantly removing the microstructure being formed by the apparatus, if desired. The effective angle D (fig. 20) of such a light polishing device must be very close to angle C. It is clear that if it is exactly the facet angle a (figure 10), it is possible to remove any debris outside the geometric projection of the facet and only remove a minimal amount of material from the facet itself. If sufficiently slight, this grinding action can sometimes improve the geometric perfection of the edge and reduce the thickness of the edge slightly, without removing the toothed structure of the microstructure formed by the edge conditioning step. Practice has shown that this subsequent slight action may slightly improve the cutting ability of the edge for some materials. It is also clear that if the angle D of this slight application step significantly exceeds angle C, it will quickly remove the desired microstructure along the edge and form a burr structure. The finishing operation must therefore be performed under highly controlled conditions at precisely the optimum angle relative to the angle a of the initial aggressive sharpening action that forms the initial facet and initial burr.

Figures 19 and 20 illustrate a motor driven three station edge conditioning apparatus comprising a sharpening station 25 designed to operate at an angle a, an edge conditioning station 26 designed to operate at an angle C and a conditioning station designed to operate at an angle D that must approach the angle C (preferably within 1 or 2 degrees) using a very slight polishing or grinding action. All of these angles are the angles between the controlled guide surfaces of the station and the contact surfaces of the abrasives 9, 9a, 38 and 38a or the surface of the hardened member 13. In this device (fig. 19 and 20), the first station 26 may, for example, use grinding disks 9 and 9a coated with 270 grit diamonds. The third station discs 38 and 38a may be made of ultra-fine 3 to 10 micron abrasive material such as alumina embedded in a flexible matrix as described in earlier us patent 6267652B1 and 6113476, the details of which are incorporated herein by reference. To avoid being so powerful that the microstructure formed in the second station is prematurely removed or destroyed, in the third station 27, it is preferred that the grit size must be very small (less than 10 microns) and the force limiting the spring 40 or its equivalent must be particularly small, preferably less than 0.2 pounds.

In fig. 19 and 20, the second blade conditioning station 26 is substantially the same as previously described with reference to fig. 17 and 18. The guide for this station holds the angle C precisely.

New surface area on the hard member 13 may be exposed by rotating the member on the threaded portion of the rod 18. Although not shown, to ensure precise angular control during edge conditioning, a hold down spring, such as spring 22, is typically used to hold the face 3 of the blade firmly against the plane of the elongated guide 24.

The surface of the discs in the first and third stations 25, 27 may, for example, be of truncated conical cross-section. In determining the precise contact angle in these stations, it is important that a vertical angle be formed between the face of the guide surface and the face of the surface on the abrasive surface at the point of contact of the blade edge with the blade facet. The guides 23, 24 and 21 are elongated allowing precise angular control as the blade face moves in close contact with the elongated plane of the guide surface. For example, discs 38 and 38a rotating on shaft 34 at a speed of about 3600 rpm may be moved laterally by sliding contact with the shaft against the restraining force of spring 40. By allowing the disk to move and glide away from the blade facet in this manner as the facet comes into contact with the surface of the disk, the chance of the abrasive material gouging the cutting edge or damaging the microstructure is greatly reduced. As previously shown in fig. 18, the lateral position of the drive shaft 34 is precisely determined by a precision bearing arrangement 35 held fast in a channel-like structure 37 connected to the device base 31. By accurately determining the lateral position of the shaft 34, the disk is accurately laterally positioned relative to the guides 21, 24 and 23.

To use the device, the motor is started and the blade is pulled along the guide plane several times with the blade facets in contact with the rotating discs 9 and 9a, while pulling alternately in the left and right guides 23 of station 1 until facets and burrs are created along the blade edges. The blade is then pulled along the elongated guide plane 24 by contacting the facet with the hardened member 13 and is pulled along the left and right guides 24 of station 2 alternately a plurality of times. The blade may then be used for cutting or it may first be pulled quickly once along the left and right guides of station 3 while keeping the blade edge in contact with the rotating disks 38 and 38 a. Station 3 must be used conservatively so that the microstructure along the edge is not removed. When the efficiency of the blade is reduced by cutting, the blade edge can be finished again in station 2. The blade can be refinished many more times before it has to be sharpened again in the above-mentioned station 1.

The foregoing description discloses a variety of unskilled devices for reproducibly creating a unique uniform microstructure along the edge of a sharpened blade when using a high precision bevel angle guide system for the blade so that a very narrow area of the blade edge adjacent the edge can be repeatedly moved across a hardened surface at exactly the same angle in successive strokes. This highly controlled action stress hardens the lower portion of the facet within about 20 microns of the edge, causing fractures to occur in a repeatable manner in a small area near the edge, which in turn causes the micro-section of the edge to break off along the edge, leaving a highly uniform tooth structure along the edge. The teeth so formed are typically less than 10 microns in height and are spaced every 10 to 50 microns along the edge. These dimensions are comparable to or significantly smaller than the width of a person's hair. Several devices have been described herein that operate by moving the blade edge against a hardened surface. However, similar results can be obtained by moving the hardened surface along the edge of the stationary blade edge, as long as the hardened surface maintains exactly the same angle at the point or area of contact in each impact. For best results, the angular difference between the plane of the blade facet and the contact plane of the hardened surface should be on the order of about 3 to 5 degrees, preferably less than 10 °.

If the angle difference exceeds 10 deg., the characteristics and number of the micro-teeth will be significantly changed and the cutting ability of the resulting edge is adversely affected. Beyond 10 deg., the microteeth are each smaller, the tooth spacing becomes more irregular and the total number of actual teeth will decrease if the angle is increased. Furthermore, it is important that for larger angles B, the edge width W is larger and the edge is no longer as sharp. The advantage of keeping the angle B small, e.g. less than 10 °, is very evident. It is also clear that in order to keep the conditioning angle C within such close proximity to the sharpening angle a in each conditioning stroke, it is necessary to use a precision guide. This is the only way in which the results can be obtained.

Two examples of devices for creating similar microstructures by moving a hardened surface along the edge of a blade with a controlled angular difference between the plane of the blade facet and the plane of the hardened surface are shown in figures 23 and 24. In the first example (fig. 23), the blade 1 is set with its axis nominally graded. The plane of the blade facet is positioned at an angle a degrees to the horizontal, where a is the angle of the upper facet 2. The angle of the plane of the hard surface 5 to the horizontal is adjustable and is shown set at angle C. The difference in angle between the plane of the edge facet and the plane of the hardened surface is therefore C-a, equal to the angle B, which optimally must be in the order of about 3 to 5 ° and preferably less than 10 °.

The rigid member 13 is adjustably connected to a post 46 mounted on a carriage 47 that is slidably movable along an angled base member 48. When the hardened member 5 is so manually moved along the base member 48 in sliding contact with the lower portion of the upper facet 2 adjacent the edge, the amount of pressure exerted by the hardened surface on the edge facet can be controlled by the user by pushing the hardened member with more or less force against the facet. The base member 48 is designed to support a blade 1 clamped to an upper platform 58 of the base 48 by a clamp 50 and a connecting screw 56.

In a second embodiment (fig. 24) employing a device with a moving hardened surface 5, the blade 1 is mounted such that the angular plane of its upper facet 2 is only B degrees different from the horizontal plane X-X corresponding to the lower surface 5 of the hardened cylinder 13 which is lowered into physical contact with the edge of the upper blade facet 2. By adjusting the angle C by the angle adjustment screw 45, the absolute value of the angle B can be changed to an optimum level. The lower surface 5 of the heavy, hard cylinder may be smooth or scored with fine radial grooves and ribs in order to provide a smaller contact area with the edge facet and thus a greater level of stress along the edge for compressing and breaking the edge as described above. If it is desired to optimise the load placed on the facet by the hardened surface 5, the weight of the cylinder may be optimised or a spring (not shown) may be added. The hard surface can be slid along the height of the post 46 attached to the carriage 47, the carriage 47 being free to slide on the angled base member 48. The bevel base member has a vertical column 50 on which is mounted an angle adjustment plate 52 which holds the blade 1 by means of a clamp 54 and a fastening screw 56.

Claims (12)

1. An edge conditioning apparatus for modifying the physical structure along an elongated edge of a metal blade having two faces which have been sharpened at their periphery to form two facets which intersect to form the elongated edge at the junction of the two edge facets, said apparatus comprising at least one precision angle blade guide, the guide faces of said guide being extended flat surfaces, one face of the blade being in constant sliding contact with said guide to guide the elongated edge of the blade into constant contact with the hardened surface of an object and to position the face of one edge facet at a precisely predetermined angle (B) relative to the plane of contact of the edge with the hardened surface, wherein said hardened surface is composed of a material which is at least as hard as the blade metal and has no tendency to wear as the blade face moves along said guide while its elongated edge remains in constant contact with said hardened surface, thereby leaving a fine microtooth structure along the edge.

2. An edge conditioning device according to claim 1 for modifying the physical structure along the elongated edge of a metal blade wherein said guide has an elongated surface with which the face of the blade is in constant contact.

3. A knife-edge conditioning apparatus for modifying the physical structure along the elongated edge of a metal blade of claim 1 wherein said guide is an elongated precision blade guide having an effective length no less than 1 inch in length.

4. An edge conditioning device according to claim 1 for modifying the physical structure along the elongated edge of a metal blade comprising at least one said hardened surface and at least one said blade guide adjacent said hardened surface, said guide comprising a physical member that contacts the blade and applies a force to press the blade against said blade guide as the blade moves along said blade guide with the edge continuously contacting said hardened surface.

5. An edge conditioning apparatus according to claim 1 for modifying the physical structure along an elongated edge of a metal blade comprising a plurality of said hardened surfaces and a said blade guide adjacent said hardened surfaces, said guide comprising an inverted U-shaped spring member having resilient cantilevered arms and an intermediate connecting portion, said connecting portion being located between said plurality of hardened surfaces, and each of said arms of said spring member extending generally downwardly along a portion of a corresponding one of said guides.

6. An edge conditioning device for modifying the physical structure along a metal blade elongated edge according to claim 1 wherein the predetermined angle (B) of adjacent facets relative to said contact surface of said hardened surface is less than 10 degrees.

7. An edge conditioning device according to claim 1 for modifying the physical structure along the elongated edge of a metal blade wherein said hardened surface is the surface of a stationary cylinder with its axis disposed perpendicular to the elongated edge of said blade.

8. An edge conditioning device according to claim 1 for modifying the physical structure along the elongated edge of a metal blade wherein said hardened surface is the surface of a rotatable cylinder with its axis disposed perpendicular to the elongated edge of the blade.

9. A knife-edge conditioning apparatus according to claim 8 for modifying the physical structure along the elongated edge of a metal blade wherein a braking mechanism prevents rotation of said rotatable cylinder unless the torque applied to said cylinder exceeds the torque applied by the braking mechanism.

10. An edge conditioning apparatus according to claim 1 for modifying the physical structure along the elongated edge of a metal blade wherein said hardened surface of said object is restrained in a predetermined rest position relative to adjacent said guide by a restraining mechanism, said restraining mechanism applying a restraining force to position said object in said position, said object being moved against said restraining force by the force applied by the edge facet contacting said hardened surface of said object.

11. An edge conditioning device according to claim 7 for modifying the physical structure along the elongated edge of a metal blade wherein said cylinder is adjustable in order to allow selection of different areas of the hardened surface of said cylinder as points of contact with the adjacent edge facet.

12. An edge conditioning device according to claim 1 for modifying the physical structure along a metal blade elongated edge wherein said hardened surface of said object has a continuous groove at the point of contact of said hardened surface with the elongated edge and the angular orientation of said groove is oriented to cross the elongated edge as the edge moves across said hardened surface with a continuous groove.