WO2000073030A1

WO2000073030A1 - Cutting wheel hub for a rotary food slicer

Info

Publication number: WO2000073030A1
Application number: PCT/US2000/009815
Authority: WO
Inventors: Brent L. Bucks; Eugene H. Cole
Original assignee: Urschel Laboratories Inc
Current assignee: Urschel Laboratories Inc
Priority date: 1999-06-01
Filing date: 2000-05-23
Publication date: 2000-12-07
Anticipated expiration: 2001-12-01
Also published as: AU5266700A

Abstract

Radially extending blade supporting projections (16) on a tensioning hub (12) for a food slicer (10) using radial blades (18) supported and tensioned by the radial projections are prevented from moving circumferentially under the influence of cutting blade impact with hard objects during cutting to avoid permanent deformation of the projections in a circumferential direction. Exemplary arrangements for preventing such circumferential movement of the projections are disclosed, including thin gap spacings (28) between projections and spacer elements (52, 64) between projections.

Description

CUTTING WHEEL HUB FOR A ROTARY FOOD SLICER

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a hub construction for a cutting wheel for a rotary food slicer using radial cutting blades mounted between the hub and a rim of the cutting wheel.

Related Technology

Rotary cutting wheels having radially extending, circumferentially spaced cutting blades have been utilized for many years to cut and slice food products to reduce the size of the original food products to that which can be readily consumed or used for further processing of the food products. An early version of such a food slicing cutting wheel is illustrated in U.S. Patent No. 2,482,523 to Urschel et al. In accordance with this early version, each cutting blade was set at a pitch angle to enhance the cutting operation and was individually tensioned between a hub and a rim of the cutting wheel by an appropriate tensioning system. An improved tensioning system for radial cutting blades of rotary food slicers was disclosed later in U.S. Patent No. 2,665,723 to Urschel et al., this improvement providing a central blade tensioner operating on cam and follower principles whereby a tensioning ring is advanced axially on the hub of the cutting wheel to uniformly draw inwardly a series of circumferentially spaced radial projections mounted in cantilever fashion on the hub and arranged to receive the inboard ends of the radially extending cutting blades that extend between the hub and the rim of the cutting wheel. This tensioning wheel system continues in use to the present day and the present invention is intended to be utilized with such a hub to improve and extend its operational life. The problem encountered with a hub having cantilevered radial projections with gap spacings between the projections is that the projections can be permanently deformed or take a permanent set when they are displaced circumferentially when reacting loads imposed by a blade striking a hard object during cutting. The permanent bending or deformation of a projection by forces that cause it to be strained beyond its elastic limit where it joins the main body of the hub prevents proper alignment of a replacement blade on the same projection. Attempts to straighten the projection to restore it to its original alignment produce varying results depending upon the skill of the individual performing the alignment and the degree of bending of the projection. Accordingly, blade impact against hard objects, a relatively frequent occurrence when the food slicing or cutting is carried out in the field results in the need to replace or rebuild the cutting wheel.

It is highly desirable to avoid permanent bending of the projections when one or more blades are struck by hard objects during cutting operations to avoid the foregoing problems.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, circumferential movement of radially extending projections (including portions thereof) extending from a cutting wheel hub and supporting radially extending blades is limited so that the elastic yield strength of the projections is not exceeded when the projections are deflected or moved in response to a blade supported thereon striking a hard object.

Various arrangements are utilized to achieve the objectives of the invention, including the use of very thin gap spacings between the projections, gap spacers to maintain the gap spacing between projections and other arrangements that will ensure continuous alignment of the radial projections despite forces imposed on the projections by cutting blades striking hard objects during cutting procedures.

Brief Description of the Drawings

With reference to the appended drawings, wherein:

Figure 1 is a vertical elevation view of a rotary cutting wheel for a food slicer showing a hub having radially extending projections for supporting one end of radially extending blades that span the distance between the projections and a rim of the wheel;

Figure 2 shows the hub portion of the cutting wheel shown in Figure 1 without the blades and rim;

Figure 3 shows the hub area of Figure 1 with a tensioning ring installed for tensioning the cutting blades by radially flexing the projections uniformly;

Figure 4 shows another hub for a cutting wheel having projections arranged to accommodate fewer cutting blades on the cutting wheel;

Figure 5 shows a hub area of a cutting wheel without the blades attached and with one of the projections displaced circumferentially so as to close a gap between the projection and the next adjacent projection;

Figure 6 shows a first embodiment of the invention whereby the gap between radial projections is minimized to prevent circumferential motion of the projections to an extent that would cause deformation of the projections beyond their elastic yield strength; Figure 7 illustrates a radial projection shown in Figure 6 displaced circumferentially so as to close a next adjacent circumferential gap but without exceeding its elastic yield strength;

Figure 8 shows another embodiment of the invention wherein a spacer element is utilized to limit motion of the radially extending projections in a circumferential direction by maintaining the gap spacing when a blade supported by the projection strikes a hard object;

Figure 9 illustrates the hub area of Figure 8 assembled with the tensioning ring and projection spacer elements;

Figures 10(A) and 10(B) show left and right perspective views of the spacer elements shown in Figures 8 and 9;

Figure 11 is a vertical exploded section view of a hub area of a cutting wheel using a different form of spacer element between radial projections;

Figure 12 shows an enlarged perspective plan view of the spacer element shown in Figure 11 ;

Figure 13 is a vertical elevation view of the spacer element of Figure 12 installed in the hub area illustrated in Figure 11 with the spacer element installed; and

Figures 14, 15, 16 and 17 illustrate other embodiments of the invention utilizing different forms of spacer devices between projections orfor limiting circumferential movement of the projections of a cutting wheel hub constructed in accordance with the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference to the appended drawings, Figure 1 shows a rotary cutting wheel 10 for a food slicer, in particular a food slicing machine for cutting food products into uniform slices or pieces. This type of cutting wheel may be used in vertical and horizontal positions but it will be assumed for the purpose of this discussion that the wheel is mounted for rotation about an axis extending in a generally horizontal plane so that the cutting wheel 10 is located in a generally vertical plane.

The cutting wheel 10 includes a hub portion 12 preferably formed of a manganese-aluminum-bronze alloy having an elastic yield strength (.02% offset) of 41 ksi (1 ,000 psi) and having a drive shaft receiving or connecting opening 14 through which a drive shaft (or an element connected to a drive shaft) for rotating the wheel 10 may extend when the wheel is mounted in its operational position. The wheel 10 could be made of other metals having known yield strengths. For example, 303 stainless steel having an elastic yield strength of 35 ksi could be used. The use of the invention, as will be described below, permits the use of metals having yield strengths that are in the above ranges without risk of permanent damage to the wheel hubs upon blade impact with a hard object.

The hub 12 includes radially extending cantilevered projections 16 for supporting one inner or proximal end of radially extending cutting blades 18 each having a sharpened cutting edge 20 on its leading edge facing in a direction of rotation of the cutting wheel as depicted by arrow 22.

The radially outer or distal ends of the blades 18 are supported by a rim portion 24 of the cutting wheel 10 and the blades are tensioned between the hub 12 and rim 24 by a tension ring arrangement to be described below.

The blades are fastened to the projections 16 and the rim 24 by appropriate high strength fasteners 26 extending in or through apertures 27 (see Fig. 2) in the projections and that are compatible with the functional requirements of the cutting wheel.

The cutting wheel 10 is generally organized and constructed in the manner of the cutting wheel illustrated in U.S. Patent No.2,665,723 assigned to the assignee of the applicant named herein. In accordance with said patent, the cutting wheel is mounted horizontally and each blade is mounted on the hub and rim so as to have an inclined pitch relative to the cutting plane of the blades. Patent No.2,665,723 is incorporated herein by reference and contains a fuller description of the cutting blade arrangement illustrated in Figure 1 herein. U.S. Patent No.4,482,523 also assigned to the assignee of the applicant named therein may be referred to for an illustration of a rotary cutting wheel for a food slicing machine in which the wheel is mounted for rotation in a generally vertical plane.

It will be noted that the projections 16 are circumferentially spaced from each other by means of gap or projection spacings 28 between circumferentially adjacent projections. Accordingly, the projections 16 are cantilevered from the central portion of the hub 12 and separated by the gap spacings 28. Each projection 16 is connected to the central portion of the hub 12 by a relatively flexible generally axially extending connecting portion 29 whereby each projection may be flexed or displaced radially inwardly and outwardly by means of a tension ring (to be described below) for the purpose of uniformly tensioning cutting blades 18 after they have been installed on the cutting wheel. Each connecting portion 29 is capable of being flexed or bent within its elastic limit so that, upon release of tension force applied to the projections, each projection springs back substantially to its original non- tensioned position.

Figure 2 shows the hub portion 12 of Figure 1 enlarged to reveal structural details thereof while omitting the blades 18 for clarity. Figure 3 is a cross-section view taken along line Ill-Ill of Figure 2 with blades 18 and fasteners 26 added for reference purposes and shows a central, axially extending boss or core 30 having external threads 32 on which is mounted by threading a tensioning nut 34 that is assembled to a tensioning ring 36 by means of low friction rollers or balls 38.

Tension ring 36 includes a peripheral tapered camming surface 40 that cooperates with and engages cam follower surfaces 42 on inner ends of projections 16 at the upper ends of connecting portions 29 as shown in Figure 3.

The tension nut and tension ring arrangement essentially corresponds with the blade tensioning arrangement described in the aforesaid U.S. Patent No. 2,665,723 and reference may be had to that patent for a more detailed description of the cutting blade tensioning arrangement shown in Figure 3 herein. Essentially, the tension ring 36 is mounted so that its camming surface 40 engages the follower surfaces 42 of the projections 16 and then the nut 34 is threaded down over the boss 30 to axially drive the ring 36 via the bearing elements 38 into engagement with the cam follower surfaces 42 of the projections 16 to cause each projection connection 29 to bend slightly radially inwardly uniformly where it is connected to the central section 12 of the hub 10. The amount of displacement of each projection 16 does not cause sufficient deformation of the proximal inner ends of the projections 16 or the connections 29 such that the material of the projections exceeds its elastic yield strength. Thus, repeated tensioning of blades can be carried out over the life of the cutting wheel without permanently deforming the projections 16 at their proximal ends where they are connected to the central portion of the hub 10. When the nut 34 is sufficiently advanced along the central boss 30, the tension in the blades 18 will be set and maintained to enable the cutting wheel to function properly during continuous slicing of food products in high speed, high volume operations. The material of the rim and blades is typically high strength steel, preferably stainless steel.

It will be noted that the number of projections 16 on each cutting wheel 10 corresponds to the number of blades mounted on the wheel. In accordance with the cutting wheel shown on Figure 1 , twenty four blades are mounted on the cutting wheel which results in the need to provide twenty four projections 16 circumferentially spaced about the hub body portion 12. Figure 4 illustrates a hub portion 44 of a cutting wheel having sixteen projections 46 which would be utilized in a cutting wheel having sixteen cutting blades mounted thereon. Since there are fewer projections circumferentially located about the periphery of the hub 44, each projection 46 is proportionally wider than the projections 16 shown in Figures 1 and 2. It will thus be evident that the proximal areas of connection between the projections 16 and the hub 12 are smaller in cross-section than the proximal connections between projections 46 and hub portion 44 shown in Figure 4. Hubs having different number of blades mounted thereon would have proportionally more or less cross-sectional area at their proximal inner ends where they connect to the main body of the hub.

A problem encountered in cutting wheels for food slicing machines of the type discussed thus far is the permanent deformation of the projections 16, 46 of the cutting wheels when a hard object impacts the cutting blade and drives the inner end of the cutting blade rearwardly relative to the direction of rotation of the cutting wheel as the blade reacts to the impact. When this occurs, the projection supporting the radially inner end of the impacted blade reacts to the load by moving rearwardly as shown by arrow the 48 in Figure 5, such movement causing the respective projection 46 (as illustrated) to close the adjacent gap spacing 46A to the extent that the projection 46 is displaced rearwardly in the direction of arrow 48 until it approaches or actually contacts the circumferentially next adjacent projection 46 on its trailing side. If the degree of motion of the projection 46 is such that the elastic yield strength of the projection 46 is exceeded, particularly in its proximal zone at connection 29 where it intersects the main hub body, the projection is permanently deformed and remains out of its proper position to a sufficient extent to prevent alignment of a replacement blade mounted later on the projection. This improper alignment of the new blade results in undesirable cutting performance of food products by the affected cutting wheel.

Obviously, smaller projections such as illustrated in Figure 1 will be more easily displaced than larger projections of the type shown in Figure 5, for example. Whether a respective projection will be permanently deformed or not by impact of a hard object with a cutting blade will depend on whether or not the projection is displaced circumferentially to an extent that the elastic yield strength of the projection is exceeded. The elastic yield strength of a projection is defined as an upper limit of strain imposed on the projection that does not exceed the ability of the projection to elastically recover from the imposed strain so as to virtually resume its original position upon removal of the strain load. The elastic yield strength is sometimes referred to as the elastic limit or yield strength of the material under consideration and is a well- known physical characteristic of structural materials to those skilled in the art.

Typically, movement of a projection as a result of blade impact with a hard object will proceed in a circumferential direction rearwardly relative to the direction of rotation of the hub until the affected projection strikes the next adjacent projection on its trailing side. Thereafter, the combined strength of the displaced projection and the unmoved projection will be sufficient to resist the displacing load imposed by the impacted blade. However, depending upon the size of the gap spacing between the projections, a projection may be deformed to an extent that its elastic yield strength will be exceeded even before it strikes the next adjacent projection, particularly if the hub contains fewer, more widely spaced and thicker projections. To alleviate this problem and to prevent permanent deformation of blade supporting projections in hubs of the type described, the present invention proposes to structurally limit the deformation of the hub projections that would otherwise result from impact of a cutting blade with a hard object during cutting wheel operation so the projection is not permanently deformed by the impact. Limiting the displacement of each projection so that the elastic yield strength of the projection is not exceeded may be carried out in various forms, example of which are described below, without limitation. It is to be understood that the broad objective of the invention is to limit displacement of each projection so that it will not be permanently deformed upon blade impact with a hard object while at the same time avoiding interference with the ability of each projection to be radially displaced by the tensioning ring previously described to effect proper tensioning of cutting blades supported by the projections. Thus, the invention has for its objective limiting the circumferentially displacement of each projection while not interfering with the radial displacement of each projection under the influence of the tensioning ring such as shown in 36 in Figure 3.

By avoiding permanent deformation of each projection that would otherwise result when a cutting blade mounted on the projection is impacted by a hard object, a broken or bent cutting blade can be replaced on the same projection in substantially perfect original alignment with the other cutting blades because the circumferential position of the projection has not been permanently affected. This enables repeated repair of broken or bent cutting blades on the same hub without change of alignment of the cutting blades.

In accordance with one preferred example of the invention, circumferential motion of each radially extending projection is limited by reducing the gap spacing between projections to a very small dimension, for example as illustrated in Figure 6. In accordance with this example, projections 46 are circumferentially spaced by gap spacings 50 that are very small, for example on the order of .025 - .031 in. (.635 - .79 mm). While this has proven successful to prevent permanent deformation of radial projections on a cutting wheel hub of the type described upon impact of a blade with a hard object, precise cutting of extremely narrow gap spacings presents a manufacturing challenge and tends to increase the manufacturing cost of the hubs. On the other hand, this solution is one that can be applied universally to various size cutting hubs having different numbers of projections thereon for supporting different numbers of blades on a cutting wheel. Also, no additional parts or pieces are required during assembly of the cutting wheel as compared with the number of pieces associated with the original cutting wheel assembly.

While a specific slot dimension has been disclosed above, it is to be understood that the gap spacing width only needs to be dimensioned such that circumferential displacement of a projection beyond its elastic yield strength is avoided before it strikes the next circumferentially spaced projection, for example as illustrated in Figure 7.

In accordance with another embodiment of the invention, circumferential displacement of each projection can be limited or prevented altogether by spacer elements inserted in the gap spacings between projections. Such an example is illustrated in Figure 8 where a spacer element 52 is shown in an exploded view of a hub 44, tension ring 36 and spacer element 52.

The fully assembled hub 44 with tension ring 36, tension nut 34 and spacer 52 installed in the gap spacing between projections 46 of hub 44 is illustrated in Figure 9. The thickness of the spacer element 52 is dimensioned and configured to maintain the gap spacing between projections 46 irrespective of loads imposed on the projections by blades impacted by hard objects. The spacers 52 are shown in more detail in Figures 10(A) and 10(B) and it will be observed that they are configured so that they do not interfere with the functioning of the tension ring 36. This is achieved by providing a notch area 54 that includes an inclined surface 56 that extends generally parallel with cam follower surface 42 (see Figure 3) on the projections. While it is not necessary that surface 56 extend precisely parallel with the cam follower surface of the respective projections between which the spacer element is inserted, the configuration of the spacer element 52 so that the notch 56 closely approximates the position of the cam follower surface 42 allows the tension ring 36 to firmly secure the spacer element 52 in position on the hub 44, and to support the spacer elements 52 against radially outward motion under the influence of centrifugal force when the hub is rotated at high speeds.

A spacer element 52 constructed in accordance with the embodiments shown in Figures 9, 10(A) and 10(B) includes a radially outwardly extending flange portion 58 and an axially extending leg portion 60. The flange portion 58 and leg portion 60 effectively fill the gap spacing between projections 46, thereby preventing circumferential movement of projections on either side of the spacer element under the influence of forces generated when a blade supported by the projection engages a hard object during cutting wheel operation.

To prevent the end of the leg 60 opposite the flange 58 from moving outwardly under the influence of centrifugal force when the hub is rotated at high speeds, a tab 62 is stamped molded, or pressed into the leg 60 so that it projects outwardly from the plane of the leg 60 (i.e., is "offset") to provide a notch or tab 62 that locks the leg 60 behind adjacent projections on either side of the spacing element 52, as shown in Figure 9.

Accordingly, when spacer element 52 is located in the gap spacing between adjacent projections 46, it is held securely between the projections by the tab 62 and the tensioning ring 36. Another embodiment of a spacer element is shown in Figures 11, 12 and 13 wherein spacer element 64 is inserted in the gap spacings between radial projections 46 on hub 44. The spacer element 64 preferably is stamped from sheet metal stock having a desired thickness sufficient to maintain the gap spacing between the radial projections cantilevered from the hub 44. The spacer element 64 as shown in Figure 12 includes a radially extending flange 66 and an axially extending leg portion 68 having a first tab 70 formed integrally in one piece from the sheet metal stock forming the spacer element 64 and a second tab 72 that defines a notch 74 located towards the axial end of leg 68.

When the spacer element 64 is located in the gap spacing 46A between projections 46 as shown in Figure 13, the tab 70 locks behind an adjacent projection 46 to prevent centrifugal displacement of the spacer element 64 in an outward direction away from the rotational axis of the hub 44. The bottom 74 of tab 72 will engage the bottom area 78 of the gap spacing 46A to locate the end of the leg 68 at the lower end of the gap spacing 46A when the retaining ring 36 is advanced to radially tension cutting blades mounted on the projections 46.

The spacer element 64, like the spacer element 52 described previously, includes a notch 80 and a sloping or inclined surface 82 that cooperates with camming surface 40 of tension ring 36 in the manner described previously in connection with a spacer element 52. If desired, multiple layers of spacer elements can be built up to make up a full spacer for the projection spacings. The term "spacer element" herein includes such multi-layered construction.

In accordance with another embodiment of the invention, as illustrated in Figure 14 individual pins or studs 84 may be inserted in threaded or smooth bores formed between projections 16 of a hub 12 of a rotary cutting wheel for a food slicer. The blades and the remainder of the cutting wheel are omitted for clarity. The pins or studs 84 may be oriented axially as illustrated in Figure 14 or could be oriented radially (not illustrated) in appropriate bores formed in the gap spacing between the projections.

In accordance with another embodiment of the invention as illustrated in Figure 15, the gap spacings between projections 16 could be entirely filled with a relatively rigid, relatively incompressible non-metallic material 86 such as a synthetic resin that is molded or otherwise disposed between the projections 16 within the gap spacings 28 between the projections. The filling material will permit the projections to flex radially under the influence of a tension ring (see Figure 3) or would otherwise accommodate the radial flexing movement of the individual projections 16.

In accordance with another embodiment of the invention as illustrated in Figure 16, circumferential movement of the projections 16 to an extent that would result in exceeding the elastic yield strength of the projections is carried out by forming the proximal root ends of the blades 18 so that they engage and buttress each other as illustrated at 88. Alternatively, a washer or shim element (not illustrated) may be inserted under each blade at its proximal root end with the shape of the shim element enabling the shim elements to engage each other at or adjacent the gap spacings 28 between the projections 16 to achieve the same objective as the portions 88 of blades 18.

In accordance with another embodiment of the invention as illustrated in Figure 17, flange portions of gap spacer elements 90 made of bent sheet metal or synthetic resin strips fastened in the gap spacings 28 between projections 16 to prevent circumferential movement of the projections 16 upon impact of a blade 18 with a hard object during a cutting operation. The elements 90 may be fastened to the projections under the blades 18 by a circumferentially extending portion formed as a bent tab of the elements 90. It will thus be seen that, in accordance with the invention, various means are possible for carrying out the primary objective of the invention, namely to prevent circumferential displacement of the radial projections extending in cantilevered fashion from the hub body of a rotary cutting wheel for a food slicer so that motion of each projection in reaction to impact of a hard object upon a blade carried by the projection will not result in permanent circumferential deformation of the projection.

While the spacer elements described above preferably are formed of sheet metal stock, it will be understood that any appropriate material that is sufficiently rigid to resist compression and to endure the rigors of a food slicer cutting wheel environment could be utilized. For example, a hard, relatively rigid plastic spacer element could be utilized and would have the advantage of relatively lightweight and inexpensive construction. In addition, the spacer elements could be molded, stamped, machined, cast, or otherwise formed, without limitation, to provide a structural element that will prevent closing of the gap spacing between adjacent radial projections of a cutting wheel hub that will produce permanent deformation of the projections under the influence of impact by a blade with a hard object during a cutting operation.

While each radial projection associated with a cutting wheel hub illustrated in the drawings and described above is manufactured in one piece integrally with the central hub body, it can be envisioned that the radial projections could be formed as separate elements and connected to the hub body by a material connecting the proximal ends of the projections to the hub body. In such event, the invention envisions the use of a suitable arrangement involving, for example, thin gap spacings or spacer elements that would prevent permanent deformation of the material joining the projections to the central hub. Various other embodiments of the projections can be envisioned by those skilled in the art and the foregoing description of preferred examples of the invention is not intended to limit the invention in any manner whatsoever.

Claims

WHAT IS CLAIMED:Claims:

1. A cutting wheel hub for a rotary food slicer comprising: a central hub portion; radially extending, circumferentially spaced blade fastening projections each connected at a proximal end to the central hub portion and separated by a spacing, said projections having a known elastic yield strength, and wherein movement of a projection relative to the central hub portion causing deformation of the moved projection beyond said elastic yield strength results in permanent deformation of such projection; each spacing dimensioned so that circumferential movement of any projection before its engagement with a circumferentially adjacent unmoved projection is limited to motion producing deformation of the moved projection that does not exceed the elastic yield strength of the moved projection.

2. A cutting wheel as claimed in claim 1 , wherein each projection is cantilevered from said central hub portion and includes a flexible connection at its proximal end connecting the projection to the central hub portion, said flexible connection arranged so that it limits radial movement of the projection relative to the central hub portion without deformation of the projection beyond its elastic yield strength.

3. A cutting wheel hub for a rotary food slicer as claimed in claim 2, wherein the central hub portion, flexible connections and projections are all formed from a single piece of metal.

4. A cutting wheel hub for a rotary food slicer a claimed in claim 3, wherein the metal has an elastic yield strength of about 41 ksi, the spacings are uniform , and the spacings do not substantially exceed .031 in. (.79mm).

5. A cutting wheel hub for a rotary food slicer comprising: a central hub portion; radially extending, circumferentially spaced blade fastening projections each connected to said central hub portion by a projection material having a known elastic yield strength, said projections spaced circumferentially by projection spacings; motion limiting arrangements associated with the projections and the spacings configured and dimensioned to prevent circumferential displacement of each projection that will produce deformation of the projection material of a displaced projection that exceeds the elastic yield strength of such projection material.

6. A cutting wheel hub for a rotary food slicer as claimed in claim 5, wherein each projection is cantilevered from said central hub portion and includes a flexible connection at its proximal end connecting the projection to the central hub portion, said flexible connection permitting limited radial movement of the projection relative to the central hub portion without deformation of the projection beyond its elastic yield strength.

7. A cutting wheel hub for a rotary food slicer as claimed in claim 6, wherein the central hub portion, flexible connections and projections are all formed from a single piece of metal.

8. A cutting wheel hub for a rotary food slicer as claimed in claim 7, wherein the metal has an elastic yield strength of about 41 ksi, the gap spacings are uniform, and the gap spacings do not substantially exceed .031 in. (.8mm).

9. A cutting wheel hub for a rotary food slicer as claimed in claim 5, wherein said motion limiting arrangements comprise a motion limiting element within each projection spacing.

10. A cutting wheel hub for a rotary food slicer as claimed in claim 9, wherein said motion limiting elements each comprises a spacer element dimensioned to fit closely within a respective spacing, and including a retainer element that secures the motion limiting element against radial movement relative to a next adjacent projection.

11. A cutting wheel hub for a rotary food slicer as claimed in claim 10, wherein said spacer elements are each formed of a single piece of metal and said retainer element of each spacer comprises a bent tab portion of the spacer element.

12. A cutting wheel hub for a rotary food slicer as claimed in claim 10, wherein said spacer elements are each formed of a single piece of metal and said retainer element of each spacer comprises an offset portion of the spacer element.

13. A cutting wheel for a rotary food slicer comprising: a hub; radially extending blade fastening projections cantilevered from the hub, each projection connected to the hub by a projection material having a predetermined elastic yield strength and separated circumferentially from a next adjacent projection by a projection spacing; a motion limiting device associated with at least one projection spacing arranged to prevent circumferential motion of at least one projection on one side of said projection spacing beyond that degree of motion that produces permanent deformation of the projection material of the moved projection.

14. A cutting wheel for a rotary food slicer as claimed in claim 13, wherein each projection is cantilevered from said hub and said projection material comprises a flexible connection connecting the projection to the hub, said flexible connection arranged and constructed so that radial movement of the projection relative to the hub is enabled without deformation of the projection and projection material beyond its elastic yield strength.

15. A cutting wheel for a rotary food slicer as claimed in 14, wherein said hub, flexible connections and projections are all formed from a single piece of metal.

16. A cutting wheel for a rotary food slicer as claimed in claim 15, wherein the metal has an elastic yield strength of about 41 ksi, the gap spacings are uniform , and the gap spacings do not substantially exceed .031 in. (.79mm).

17. A cutting wheel for a rotary food slicer as claimed in claim 13, wherein said at least one motion limiting device comprises a spacer element dimensioned to fit closely within a respective projection spacing.

18. A cutting wheel as claimed in claim 17, wherein each spacer element is formed of a single piece of metal and includes a portion connected to the spacer element that is arranged to prevent radial motion of the spacer element relative to a next adjacent projection during rotation of the cutting wheel.

19. A hub for a rotary cutting wheel, comprising: a central hub portion; radially extending circumferentially spaced cantilevered projections each connected to the central portion by a material having a predetermined elastic yield strength; means for preventing each of said projections from moving circumferentially relative to the central hub portion to an extent that would result in said material being deformed beyond its elastic yield strength.

20. A hub as claimed in claim 19, wherein said central hub portion and projections are formed in one piece of metal; each projection is cantilevered from said central hub portion at its proximal end by means of a flexible connection having a predetermined yield strength connecting the projection to the central hub portion; said flexible connection permitting limited radial movement of the projection relative to the central hub portion without deformation of the projection and flexible connection beyond their elastic yield strengths; said means for preventing said projections from moving circumferentially comprising spacer elements disposed within respective spaces between said projections.

21. A hub as claimed in claim 20, wherein said spacer elements are constituted of individual separate members.

22. A hub for a cutting wheel comprising: a central hub portion; radially extending cantilevered projections circumferentially spaced by projection spacings about the central hub portion; said central hub portion and projections integrally formed from a single piece of material having a known elastic yield strength defining a limit of deformation beyond which the material is permanently deformed; a motion limiting element within each projection spacing configured to prevent motion of any projection in a circumferential direction tending to reduce the gap spacing between the moved projection and a next adjacent projection exceeding that motion that produces a deformation of the moved projection that exceeds the elastic yield strength of the moved projection.

23. A spacer element for maintaining circumferential spacings between outwardly projecting radial projections connected to and circumferentially spaced about a central hub member, comprising: a flange portion dimensioned to fit closely within a circumferential spacing; a securing portion configured so that it structurally retains the spacer element against radially outward motion relative to a circumferential spacing when the flange is installed in a circumferential spacing.

24. A spacer element as claimed in claim 23, wherein the spacer element is formed of a sheet metal member and the securing portion is a bent tab constituting part of the sheet metal member.

25. A spacer element as claimed in claim 23, wherein the securing portion is an offset portion of the member.

26. A spacer element as claimed in claim 23, wherein the securing portion comprises a notch area defining an inclined surface adjacent said flange portion.

27. A method of operating a rotary cutting wheel in a food slicer, wherein the cutting wheel includes a central hub portion; a rim portion concentrically surrounding the hub portion; cutting blades having cutting edges, and radially connected to and spanning the hub and rim portions with the cutting edges facing towards the direction of rotation of the cutting wheel; said hub portion including radially extending, circumferentially spaced projections for fixedly supporting the radially inner ends of the cutting blades, said projections having a known elastic yield strength, the method comprising: driving the wheel in rotation; upon impact of a blade with an object hard enough to cause the blade to react the load imposed by the impact upon the respective projection to which the blade is secured and to cause the said projection to be moved in a direction opposite the direction of rotation of the wheel, limiting the degree of movement of the projection so that the projection is not deformed to an extent exceeding the elastic yield strength of the projection, thereby enabling the projection to elastically return to the position it assumed before impact.

28. The method according to claim 27, wherein limiting the degree of movement of the projections is carried out by inserting spacer elements in the spacings between circumferentially adjacent projections, said spacer elements arranged to substantially maintain the circumferential spacings between said projections upon said impact.