US2499786A - Knife steel - Google Patents

Description

March 7, 1950 s N 2,499,786

KNIFE STEEL Filed Aug. 2, 1948 JNVENTOR YRMH SHAW A T TOR/VEX Patented Mar. 7, 1950 UNITED STATES tPATENT glam OFFICE 10 Claims.

The present invention relates to knife steels. While the invention is of general applicability and is suitable for home use, it is particularly useful in butcher shops and other establishments where the use of very sharp knives is essential to the trade.

Knife steels comprising a rod of steel, usually tapered and roughened, have long been used for increasing the cutting properties of knives. The action of the steel on the knife is apparently more of a stropping action tending to line up the microscopic sections of the cutting edge rather than an abrasive action intended to remove material from the knife.

In a butcher shop, a knife steel is usually hung over, or provided near, every chopping block or cutting table. Each time, before cutting a piece of meat, the butcher customarily reaches for the steel, strokes the knife on it several times, stroking first one side and then the other, and after he has finished he puts the steel back in the place where it is kept. This requires time and effort which, when magnified by recurring dozens or perhaps hundreds of times a day, reaches considerable proportions. It means loss of time and increase of fatigue.

Moreover, considerable skill is required in steeling a knife properly with the conventional steel. The stroking of the knife and the angle of contact between the knife and the steel must both be just right. This is no problem to an expert butcher. However, in these days of scarcity of skilled craftsmen, it is frequently necessary to employ persons who are not experts. Moreover, conventional knife steels have never been any too satisfactory for home use since most householders are not sufficiently skillful in using them.

It is an object of the present invention to provide a knife steel which can be mounted on the side of a chopping block or cutting table, or in other convenient location, and is used merely by drawing a knife through it without removing the steel from its support. The time and effort required in reaching for a steel and then putting it back in place is wholly eliminated since the steel in accordance with the present invention is always ready for use and need not be moved. Still more time is saved by the fact that the knife need be drawn through the device only one or two times to produce a fine edge. A further advantage is that use of my novel knife steel requires little or no skill to produce excellent results. It is, hence, ideally suitable for home use as well as for use in butcher shops, packing plants,

hotels, restaurants and other commercial establishments.

Other objects and advantages of my invention will appear from the following description of the preferred embodiment of the invention which has been illustrated by way of example in the accompanying drawings.

In the drawings:

Fig. l is a side elevation of a knife-steel in accordance with the present invention.

Fig. 2 is a top view.

Fig. 3 is an end view as seen from the left hand end of Fig. 1.

Fig. 4 is a fragmentary cross-section of one of the spring brackets taken approximately on the line 4-4 of Fig. 1.

Fig. 5 is a View similar to Fig. 2, but showing a modification.

Fig. 6 is a cross-section approximately on the line 6-6 of Fig. 5.

Fig. '7 is a diagrammatic view representing the outline of a cross-section taken approximately on the line 'l-l in Fig. 1 but on an enlarged scale and showing only the outlines of the cross-section.

The embodiment of my invention shown in Figs. 1 to i comprises a base, a pair of reversibly symmerical elongated knife steel sections having inner surfaces which are substantially in contact for a portion of their length and gradually diverge at one end in a sharp V and resilient means for pivotally mounting the steel sections on the base so as to turn about their longitudinal axes and to be resiliently pressed into contact with one another while being separable against the action of the spring brackets to allow a knife to be drawn between the sections. n

The frame or base It] can be of any suitable form and material, being shown as a flat plate having a plurality of screw holes H for attaching it to the side of a chopping block or cutting table so that the base plate is substantially vertical. These screw holes are shown merely by way of example, it being understood that any other suitable attaching means can be provided.

The steel sections I2 and 13 are similar to sections of a conventional knife steel. In other words, each of the steel sections comprises a length of hardened steel rod which is preferably magnetized and preferably has its surface slightly rilled or roughened, for example by fine longitudinally extending ribs and grooves. The steels are shown as being of ovoid cross-section (Fig. '7), the term ovoid being used generically to designate a figure having a major axis and a minor axis, such for example, as an ellipse or semi-ellipse or a crescent or double crescent or slope gradually inwardly and meet the base such as that illustrated in Fig. '7.

The steels l2 and I3 are of such shape and are mounted in such relation to one another that their inner or meeting faces are in contact, or substantially in contact, with one another throughout a portion of their length and then gradually diverge in the form of a sharp V (Figs. 2 and 3). The steel sections may be substantially straight, in which event the portions of the surface that are in contact are progressively flattened a greater amount in order to provide substantial contact over an appreciable increment of length. Alternatively, at least one of the sections is curved in a longitudinal direction in order to provide the desired contact and divergence. In the preferred form of the invention shown in Figs. 1 to 4, both steel sections are curved, being reversely symmetrical to one another. As will be seen in Figs. 2 and 3, the lower portions of the steels are approximately straight to provide substantial contact between the two steels for a distance preferably amounting to at least one-quarter, and not more than three quarters, the length of the steel section. The upper end portions of the steel sections are curved outwardly from one another so. as to diverge in a sharp V.

At opposite ends, the steel sections i2 and I3 are provided with means for mounting the sections on the base l0. At least one, and preferably both, of the sections are pivotally mounted so as to be capable of turning a limited amount about their respective longitudinal axes. In the form shown in the drawings, the steel section [2 ends with axially projecting shaft portions i5 and IS. The steel section 13 is in like manner provided with axially projecting shaft portions l1 and I8. These projecting shaft portions may be integral with the steel sections or may be in the form of stub shafts or pins set into holes in the end of the steel section. It will be understood that alternative pivotal mounting means can be provided, as for example, merely by drilling holes in the ends of the steel sections to receive pins or other projections mounted On the base.

The steel sections are mounted on the base in such position that, except for their divergence, they are approximately parallel to the base but are at an appreciable angle to the horizontal, for example an angle of not less than degrees and preferably 20 degrees or more. The longitudinal axes of the two sections i2 and I3 are in a common plane which is approximately perpendicular to the plane of the base. In the embodiment shown in Figs. 1 to 4, the steel section 12 is supported by brackets 2| and 22 comprising strips of spring steel secured to the base by any suitable means, such as screws or rivets 23 and engaging the stub shafts l5 and 18 respectively in such manner as to permit pivotal movement of the steel section l2 about its longitudinal aXis. Pivotal connection is conveniently provided merely by curling the ends of the bracket strips 2! and 22 around the shaft portions !5 and 56 respectively.

The other steel section I3 is mounted on the base by somewhat similar spring brackets 25 and 2B which are, however, considerably longer and are secured to the base at a considerable distance below the steels by suitable screws, rivets, or other fastening means, 21. The upper portions of the brackets 25 and 26 are approximately parallel with the base. The lower portions curve in a sharp angle, as indicated at 23. The spring strips forming the brackets 25 and 26 are preferably convex on their inner surfaces, as illustrated in Fig. 4. In addition to the advantages pointed out below, this form of strip permits the use of lighter strip while still securing the required stiffness. Instead of using strip stock for the spring brackets, round wire or other stock may be used. For example, the brackets can be formed of relatively heavy spring wire having the end portions bent at approximately right angles and projecting into holes in the ends of the steel sections i2 and [3 to provide the desired pivotal mounting.

The spring brackets, and in particular the longer spring brackets 25 and 26, resiliently press the steel sections l2 and I3 into contact with one another. The bracket 26, by virtue of being longer and hence somewhat more flexible, provides lighter spring pressure than the bracket 25.

The knife steel in accordance with my invention is used simply by drawing the edge of the knife blade through the sharp V between the steel sections I2 and 13. The position in which the steel sections are mounted makes it easy and natural for the blade to be drawn through in proper relation to the steels. As the blade is drawn through with a slight amount of downward pressure, it passes down between the steel sections, separating them slightly against the resilient action of the spring brackets. The resiliency of the brackets assures the proper pressure between the steels and the knife blade throughout the draw. The shape of the brackets and their relative stiffness are such that correct pressure and correct angle of contact are assured at all times.

As the knife blade is drawn between the steel sections, the sections tend to turn on their longitudinal axes, such turning being permitted by the pivotal mounting of the sections. This movement of the steels has two effects. It presents new surfaces of the steels to the knife blade and, in cooperation with the spring supports, it assures firm contact between the steels and the knife. As illustrated in Fig. 7 which represents diagrammatically the cross-sectional outline of the steels and their respective pivotal axes, the curvature of the inner or working face of each steel is less than that of a circle having a radius equal to the distance from the pivotal axis 0 of the section to the nearest point C of the working face ACB. In other words the curvature of the surface ACB is less, i. e., flatter than that of a circle having a radius equal to the distance ll-C. The distance from the pivotal center 0 to the edges A and B of the working face is greater than the distance from 0 to the midpoint C. Normally, the midpoints C of the opposite working faces of the two steels are in contact with one another. As the sections turn slightly about their pivotal axes 0 due to the friction of the knife blade as it is drawn through between them, the pivotal movement tends to bring into contact with the blade new surfaces of the steel, for example siu'faces D, which are more distant from the pivotal axes than the surfaces C. This causes the steels to press firmly on the knife blade so that predetermined pressure of contact is assured.

It is intended for the knife blade to be drawn between the steels in a direction approximately parallel to its cutting edge. If, through the application of excessive downward pressure, the

knife is forced all the way down so as to come out below the steels, no damage is done since the way in which the spring brackets 25 and 26 are mounted provides adequate clearance. Moreover, even if the blade should strike one of the brackets, it would be a glancing blow on a convex surface similar to that of the steels so that the edge will not be appreciably blunted. The same is true even if the knife edge should come all the way down to the point at which the bracket is attached to the base, since the sharp V 28 between the bracket and the base (Fig. 3) is similar to the V between the steel sections and, hence, exercises a sharpening rather than a dulling action.

The embodiment of my invention shown in Figs. 5 and 6 is basically the same as that of Figs. 1 to 4 and like parts are designated by the same reference numerals. The embodiment of Figs. 5 and 6 is different in that portions of the steel sections H2 and H3 are cut away to accommodate inserts 32 and 33 of an abrasive material, for example, Carborundum. The abrasive inserts 32 and 33 are held in place by suitable means, for example, by providing dovetailing surfaces. Alternatively, they may be held by spring clips 35, as illustrated in Figs. 5 and 6. The working surfaces of the abrasive inserts form smooth continuations of the working surfaces of the respective steels. However, as the abrasive material will usually wear more rapidly than the steel, the leading edge of the steel section may be rounded slightly so that the knife blade does not strike any sharp corner. The abrasive inserts are replaceable so that they may be renewed from time to time, as desired, or may be replaced by inserts of finer or coarser abrasive, as desired.

The working surfaces of the sections H2 and H3 are thus formed of abrasive material for a portion of their length and of steel in another portion of their length. The portion of knife steel and portion of abrasive may be united in other ways, for example, by mounting both of them end to end on a suitable backing strip. In using the embodiment of Figs. 5 and 6, the knife is first drawn through between the abrasive portions 32 and 333 and then drawn through between the steel portions H2 and H3. While the steel portions H2 and H3 are shown in Fig 5 as being substantially parallel and in contact, it will be appreciated that, because of the greater resiliency of the bracket 25, the steels will be slightly separated and form a sharp V with one another as the knife blade is drawn down between them. The embodiments of Figs. 5 and 6 thus provides both an effective abrasive action and an effective steeling action.

While the invention has been described with reference to the specific embodiment illustrated in the drawings, it will be understood that these are shown merely by way of example and that modifications may be made in them within the scope of the appendant claims. The invention thus provides a knife steel which is so convenient to use as to make possible substantial savings in time and effort in establishments such as butcher shops, meat-packing plants, hotels and restaurants, and is substantially foolproof so that it can be used even by an inexperienced person and is, hence, eminently suitable for household use as well as commercially.

I claim:

1. A knife steel comprising a pair of reversely symmetrical elongated knife steel sections having inner surfaces which are substantially parallel for a portion of their length and gradually diverge at at least one end, means for pivotally mounting each of the sections to turn about its longitudinal axis, the mounting means of at least one of the steel sections being resilient to press the parallel surface portions of the sections resiliently into contact with one another, the inner surfaces of said parallel portions being of less curvature in cross section than a circle having a radius equal to the distance from the respective pivotal axes of said sections to the central portions of said surfaces.

2. A knife steel comprising a pair of reversely symmetrical knife steel sections of non-circular cross section, means for pivotally mounting said sections to form a sharp V with one another and to turn about their respective longitudinal axes, said axes being located in a common plane, the mounting means of at least one of the sections being resilient to press said sections resiliently together so that they are normally in contact but are separable to allow a knife to be drawn between them.

3. A knife steel comprising a vertical base plate, a pair of elongated knife steel sections at least one of which is curved longitudinally, means for pivotally mounting said sections to form a sharp V with one another and to turn about their respective longitudinal axes, said axes being normally disposed in a common plane, the mounting means of at least one of the sections being resilient to press said sections normally into contact with one another but to permit their separation against the action of said resilient mounting to allow a knife to be drawn between the sections.

4. A knife steel comprising a vertical base, an elongated steel section mounted on the base substantially parallel thereto and at an angle to the horizontal, a second similar steel section, spring brackets attached to the base a substantial distance below the first steel section and pivotally supporting the second section by its opposite ends so as to form a sharp V with the first section with the axes of the two sections in a common plane perpendicular to the base, the second section being resiliently pressed against the first section by the spring brackets while permitting sufficient separation of the sections against the action of the spring brackets to allow a knife to be drawn between the sections.

5. A knife steel according to claim 4, in which the upper and inner sides of said spring brackets are convex.

6. A knife steel comprising a vertical base, a pair of elongated, longitudinally curved knife steel sections of ovoid cross section, a pair of spaced brackets secured to the base and pivotally supporting one of said sections by its opposite ends in a position approximately parallel to the base and at an angle to the horizontal, a second pair of spring brackets attached to the base a substantial distance below the first section and pivotally supporting the second section by its opposite ends so as to form a sharp V with the first section with the longitudinal axes of the two sections in a common plane perpendicular to the base, the second section being resiliently pressed against the first section by said spring brackets.

'7. A knife steel according to claim 6, in which each steel is provided for in the upper portion of its length with an insert of abrasive material.

8. A knife steel comprising a pair of elongated sections, means for pivotally mounting said sections to forma sharp V with one another and to turn about their respective longitudinal axes, the mounting means of at least one of the sections being resilient to press said sections resiliently into contact with one another while permitting their separation against the action of the resilient mounting to allow a knife blade to be drawn between them, the knife engaging portion of one portion of each section comprising a section of knife steel and the knife engaging portion of another portion comprising an abrasive section.

9. In a knife sharpener, a composite sharpening clement comprising a section of knife steel, said section of steel being reduced in cross section for a portion of its length to provide a supporting face set back from the working face of the adjacent full cross section portion of the steel, an abrasive stone supported on said supporting face and detachably united with said steel, said stone having a working face forming a smooth continuation of the working face of said steel.

10. In a knife sharpener, an elongated sharpening element comprising a section of knife steel, said section being reduced incrosssectionfor a portion of its length to provide a supporting face set back from the working face of said steel, an elongatedsectionof abrasive stone supported on said supportingja ce and having a working face forming acontinuation of the working face of said steel, and spring clips removably holding said abrasive stone in place.

YERME H. SHAIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 602,192 Maillot Apr. 12, 1898 1,059,491 Schwartz Apr. 22, 1913 1,068,973 Brown July 29, 1913 1,463,653 Loomis July 31, 1923 1,907,870 Reader May 9, 1933 2,432,231 Elphee Dec. 9, 1947 2,443,821 Gray June 22, 1948

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