GB1577762A

GB1577762A - Meat extruder and cutter having an overhanging blade cutter bar

Info

Publication number: GB1577762A
Application number: GB16224/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-11-26
Filing date: 1977-04-19
Publication date: 1980-10-29

Description

(54) MEAT EXTRUDER AND CUTTER HAVING AN OVERHANGING BLADE CUTTER BAR (71) I, JAMES HAYWOOD BARNES, of 283 Tolbert Street, Wadsworth, Ohio 44281, United States of America, a citizen of the United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: In the meat cutting and/or extruding fields, it is believed that the commerical practices therein have remained relatively static for a number of years. That is, apertured flat metal discharge or cutter disc plates are provided in extrusion apparatus having a driven rotary screw therein and with this screw carrying a cutter knife at the end thereof positioned at the flat metal extrusion disc.

The knives as used presently have in general comprised a cast structure having, for example, four substantially radially extending fingers thereon and with a hardened cutter insert being provided at a leading edge of each of the cutter blades and forming a very localized or knife edge contact only for engaging the discharge or extrusion disc for presumably cutting meat as forced into the apertures in the extrusion disc. The blades frequently have torn the meat apart rather than cutting the meat.

These cutter blades and extrusion discs as used commerically today have required relatively frequent maintenance, repair or inspection services since the cutter blade tends to become dull relatively rapidly in use and the cutter discs themselves may become gouged or roughened.

The meat extrusion process is used primarily for forming hamburger meat and the like. Naturally, it is desirable to provide this meat in a saleable or as useful a condition as possible and it is desired that this extruded meat will have a good shelf life when ground and placed in cold storage until sold. Obviously, it is quite desirable to extrude or form the hamburger or cut meat particles as rapidly as possible and to maintain maximum efficiency from the extrusion equipment.

According to the present invention there is provided a rotary cutter for a meat cutting and/or extruding device including an apertured flat-faced discharge means, said cutter comprising a plurality of cutter blades extending substantially radially from an axis of rotation, each of said cutter blades having a flat surface, said flat surfaces substantially lying in a common plane perpendicular to said axis, and including a cutting edge at the foremost portion of said surface for an intended direction of rotation and a leading edge axially spaced from and in advance of said cutting edge, said leading and cutting edges being connected by a smooth continuous surface extending forwardly in the direction of rotation from said cutting edge to the leading edge.

The general object of the present invention is to provide a novel and improved rotary cutter means or cutter knife for use in meat cutting and extruding devices and wherein the cutter knife has a plurality of cutter blades that have overhanging leading edge surfaces thereon smoothly connected to a leading cutting edge on each blade, which cutting edge is at the circumferentially forward margin of a flat bearing surface provided on each of the cutter blades and positioned adjacent or against a flat face of an apertured discharge means with which the cutter knife is used.

An advantage of the invention is that it provides an improved rotary cutter adapted to extrude or force meat and similar products through an associated discharge means rapidly and at low temperatures to obtain a desirable product having improved or desirable length shelf time.

Another advantage of the invention is that it may be used to provide an improved meat grinder wherein the meat is cut or ground under low temperture conditions by a device that can be operated without generating a large amount of heat.

Another advantage of the invention is that it may be used in a meat grinder having a discharge assembly including a plastics extrusion disc and a backup metal disc and support means for the extrusion disc.

Another advantage of the invention is that its use improves the service life of meat cutter and extruding devices, especially when used in a meat extruder wherein the cutter knife operates against a low friction plastics material which does not rapidly dull the knife or heat up the cutter and extrusion means.

Another advantage of the invention is that it provides a rotary cutter having improved properties both in the amount of meat that can be processed in a cutter means assembly with minimum or no maintenance thereon and where an improved type of a bearing action is provided between the cutter blades and an associated flat surfaced apertured extrusion disc; and to use a one piece metal casting as a cutter knife.

A preferred embodiment of the invention comprises a rotary cutter means for use in meat extruding devices, including a plurality of cutter blades that have overhanging leading edges joined by inclined surfaces to a cutting edge at the foremost edge of a flat bearing surface provided on each cutter blade adjacent the extrusion disc. A radially extending slot may extend the operative length of each cutter blade, interrupting the flat surface thereof to provide two circumferentially spaced radially extending cutter edges on each cutter blade. A cutter device which has a self sharpening action on the cutting edges thereof is provided by bearing engagement of one surface forming a portion of the cutting edge against an associated extrusion disc.A cutting edge on a cutting blade of the cutting device of the type described is advantageously formed between surfaces on the cutter blade meeting at substantially 90 . Substantially circumferentially directed small recesses in radially spaced portions of a cutter blade and extending a short circumferential length thereof may be provided to release quantities of meat engaged with the entire leading edge surface of the cutter blade and not force or move all of such material contacted toward the associated extrusion disc for extrusion and cutting action; and to control the rate of extrusion and cutting action of the material processed at least partially by the number and size or depth of these bypass recesses formed on the leading edges of the individual cutter blades.

Preferred features and advantages of the invention will be made more apparent as the specification proceeds.

In the accompanying drawings: Fig. 1 is a side elevation, partially broken away and shown in vertical section, of a meat cutting or extruding device having the cutter means of the invention associated therewith; Fig. 2 is a section on line II--II of Fig. 1 of the cutter blade of the invention; Fig. 3 is a fragmentary plan of a portion of the cutter means of the invention; Fig. 4 is a front elevation of the cutter knife of Fig. 3; Fig. 5 is a section of a cutter blade taken on line 5-5 of Fig. 3; Figs. 6 and 7 are sections of modifications of the cutter blades of the invention; Fig. 8 is a longitudinal section of another embodiment of the apparatus of the invention, Fig. 9 is an elevation of a portion of a plastics cutter disc of Fig. 8; and Fig. 10 is a plan view of a portion of a modified cutter knife of the invention; Fig. 11 is a side elevation ofthis cutter knife; Fig. 12 is a side elevation of one cutter blade of this cutter knife.

When referring to corresponding members shown in the drawings and referred to in the specification, corresponding numerals are used to facilitate comparisons therebetween.

A meat cutting or extruding device of including a rotary cutter embodying the invention includes an apertured flat faced discharge means or extrusion disc against which the rotary cutter abuts.

The cutter preferably includes a one piece metal cutter knife having a plurality of cutter blades extending substantially radially thereof with each blade having an overhanging leading edge that is axially spaced from the flat face of said extrusion disc, a cutting edge on each cutter blade adjacent an extrusion disc, and a continuous surface being formed on each cutter blade and extending from said leading edge to the cutting edge, each cutter blade having a flat surface thereof normally bearing on the flat face of the extrusion disc, and with the cutting edge being at the foremost edge of the flat bearing surface. The cutter blades preferably have radially extending slots in each of the flat bearing surfaces and extending the length thereof to form a pair of parallel cutting edges on each cutter blade and positioned in spaced circumferential relation.The cutter blades of the invention are relatively massive in cross section and normally are of greater circumferential length than axial depth, the flat bearing surfaces distributing any axially directed assembly pressures over these flat bearing surfaces, and with the cutting edges of the cutter blades being formed by surfaces intersecting at angles of substantially 90 . Extrusion flow pressure relieving recesses may be provided in leading edge portions of the cutter blades.

With reference to the details of the construction shown in the drawings, a meat cutting and/or extruding device is indicated as a whole by the numeral 10. This device includes a tubular housing 12 that has a driven extrusion screw 14 positioned therein. This screw 14 and housing 10 are of conventional construction and meat or other material to be extruded is suitably fed to a lefthand input portion (not shown) of the extrusion device.

The screw can be manually or power driven, as desired, to force the meat from the device in processed form.

At the extrusion or discharge end of the device 10, an apertured flat faced discharge means or extrusion disc 16 is provided and it is secured over the open end of the tubular housing 12. Normally the disc is secured in position as by a conventional collar 18 releasably engaging the end of the housing 12 and abutting the disc 16 against a shoulder 20 formed on the end of the housing 12. The extrusion screw 14 may have an end that is journalled in or positioned by an aperture in the extrusion disc 16. The portions of the device 10 described hereinabove may be of any known construction.

A conventional type of an extrusion disc 16 is secured in the apparatus, and a rotary cutter means indicated as a whole by the numeral 22 is operatively carried by the end of this screw 14 for meat cutting and extrusion action.

Such cutter means is a one-piece metal casting. This rotary cutter normally has a substantially square aperture 24 formed therein that engages a complementary shaped end portion on the screw, and with an end of the rotary cutter means tightly abutting against an end portion of the screw 14. The cutter blades also have a flat operative face or surface 36 abutted against a flat face 26 of the extrusion disc 16.

This disc-like cutter knife has a plurality of cutter blades 28 extending substantially radially thereof in equally spaced circumferential relation. The width of each of blades 28 may be offset slightly from and parallel to a radially extending axis or be centered on such axis, as desired. Each of these cutter blades has an overhanging leading edge 30 formed thereon and this leading edge 30 is spaced axially from the flat face 26 of the extrusion disc 16. Such leading edge is connected to a cutting edge 32 formed on each cutter balde by a continuous surface 34. This surface 34 may be of a slightly concave shape as shown in Fig. 4 of the drawings, but with such face smoothly extending from the leading edge to the cutting edge and forming an angle of slightly more than 90" with flat surface 36 on each of the cutter blades.These surfaces 36 define, with the other flat surfaces on the other cutter blades a plane perpendicular to the axis of rotation so that such flat surfaces can be abutted on and bear smoothly against the flat face 26 of the extrusion disc.

Preferably and as shown each of the cutter blades 28 has a radially extending slot or recess 40 formed in its flat face 36. This slot extends the operative length of the cutter blade and is relatively deep so that, when the rotary cutter member is in operation, small quantities of processed material, and usually bone chips, tend to accumulate in this slot 40. By this slot 40, a second cutting edge 42 is formed on each of the cutter blades. Such cutting edge is formed at the 90" angle provided by a portion of the flat face 36 of each of these cutter blades and the substantially radially inwardly extending adjacent flat wall 44 of this slot 40. The cutting edge 42 is parallel to the cutting edge 32 of the same cutter blade but is spaced slightly circumferentially in relation thereto.

It should be noted, as shown in the drawings, that each of these cutter blades is relatively massive as it has an effective circumferential length indicated as between the lines a-a and b-b of Fig. 4, and it has an axial length or thickness at its outermost end indicated by the distance between the lines c-c and d-d so that the circumferential length of the blade is greater than its than axial depth throughout most of it length. Preferably the entire rotary cutter means 22 is formed as a one piece casting from suitable material such as high carbon steel whereby a tough, durable cutting member has been provided and a large quantity of meat can be processed without any resharpening of the blade unit or any other maintenance thereon.In fact, the blade unit has a definite self-sharpening action inasmuch as the flat bearing surfaces 36 of each cutter blade in use are pressed tightly against the adjacent flat surface 26 of the extrusion disc. That is, in the conventional assembly of an apparatus embodying the invention, axial pressures are placed on the collar 18 or other member used to hold the assembly together and this forces the cutter disc 16 against the flat surfaces or faces 36 of the cutter blades.

The individual cutter blades are of greater axial depth adjacent the hub of the cutter means, as seen in Fig. 4, and hence are here axially deeper than their circumferential length. But for the greater portion of their lengths, the blades decrease in axial thickness and the circumferential length normally is the longer dimension.

The rotary cutter means 22 requires no added cutter bars or the like, but does form and maintain in use sharp cutting edges at corners formed by surfaces meeting at substantially 90" angles.

Yet a further action that seems to be obtained by the provision of grooves 50 in the overhanging leading edges of the cutter blades is that a good mixing action is obtained at the front of the cutter blades on the meat being processed. The apparatus achieves a faster production rate than prior devices.

In the use of the invention, it appears that the leading edge 30 functions better in these cutter blades if it is formed to a continuous, slightly concavely curved surface as shown in the drawings. However, any inclined surface from an angle of about 88" with the plane defined by the contacting flat surfaces 26 and 36 down to an angle of about 10 would function satisfactorily. Normally the overhanging leading edge surface would have a lower limit of an angle of from about 30 to 45" with the adjacent flat surface of the cutter disc and usually the angle formed between these two surfaces would be in the vicinity of about 75 to 850 but it could even go a little higher. In fact, good cutting and extruding action occurs when the cutter blade is of the shape of the blade 28b of Fig. 7.

Here, the leading edge 30a makes an angle of about 90" with the plane defined by the associated flat face of the cutter disc 16.

These cutter blades function effectively until the flat surfaces 36 thereof have been worn down to the depth of the slot or groove 40 provided in the cutter blade arm. A very large quantity of meat normally can be processed with no sharpening of the cutter blades being required. The lock ring or collar 18 must be designed so that by tightening it after use of the apparatus of the invention, the cutter disc 16 is maintained in pressure engagement with the flat surfaces 36 of the cutter means. Such pressure engagement is maintained in use of the cutter means of the invention. Should the cutting edges 32 and 42 become dull or irregular, grinding off only a few thousandths of an inch from the flat aligned surfaces 36 sharpens the blades for continued good cutting action.The screw 14 naturally is positioned to abut on means (not shown) whereby it does not move away from the cutter disc 16.

In test use of an extrusion device or cutter means embodying the invention, it has been found that in some instances it is desirable to reduce the rate of feed or flow of meat or other processed material through the device of the invention. Hence, it has been found that by the provision of radially spaced, circumferentially short recesses, or grooves 50, 50a, 50b, 50c, etc. in the leading edge 30 of each cutter blade, the rate of flow or movement of meat through the device can be controlled.

These grooves aid in permitting some of the meat being processed to slide by the rotary cutter means without being forced into and through the extrusion disc on its initial contact with a cutter blade.

Fig. 5 shows that the bottom of the recesses 50 may be inclined at an angle of, for example, about 35 to the cutter disc to facilitate flow of meat past the cutter blade. These recesses can vary appreciably in size and shape to aid in controlling the rate of meat flow through a cutter apparatus of the invention. By inclining the axes of the recesses radially inwardly or outwardly at small acute angles, the mixing action of the meat being processed is improved. The recesses 50 seem to aid in forming a sturdy cutter blade with good properties for meat extrusion and also to aid in control of the rate of extrusion by variation in the number, shape and size of the recesses. The recesses preferably do not extend circumferentially more than about 25 to 40% of the circumferential width of the blade.The extrusion rate also can be varied by change of the axial depth of the cutter bars.

Fig. 6 shows a flat, inclined leading surface 70 on a cutter blade 28a that connects to a sharp leading edge 72. Recess 74 for pressure relief of the extruded material also is shown.

A plurality of these recesses 74 are provided in radially spaced portions of the leading edge areas of each of the cutter blades or arms.

Another design of a cutter blade arm 170 is shown in Fig. 7. The arm 170 has a modified overhanging L-shape in section terminating in a leading sharpened edge 172 which is offset axially from an apertured extrusion disc or plate 171 with which it is used. The arm includes a base section 174 that has a sharpened cutting edge 176a on a flat blade surface 176 which may be relieved at a desired small acute angle to provide clearance towards the trailing edge of the blade, or the surface 176 may abut on the face of the disc 171. By this overhanging leading sharpened edge portion 172, the meat can be sliced preparatory to the final extrusion action thereon and the forcing of the meat through the cutter disc.An overhanging tapered or shallowly concave surface 179 is provided on the cutter blade to extend axially inwardly toward the cutting edge 176a of the blade and towards the cutter disc to aid in forcing the meat toward the disc 171 for final cutting and extrusion.

A modified meat cutting or grinding device is indicated as a whole by the numeral 100 in Fig. 8. The device is of substantially conventional construction insofar as it includes a metal frame 112 having any desired type of a support provided therefor and which frame 112 has a tubular portion defining a cylindrical extrusion chamber 114. A conventional extrusion screw 116 is positioned in the chamber on the longitudinal axis thereof to substantially fill the same. This screw has a manual power crank or handle or a drive member connected thereto for rotating the screw and forcing meat received in the chamber 114 axially thereof. This meat is fed into the chamber through a conventional hopper (not shown) operatively connecting thereto. At the discharge end of the chamber 114, a rotary cutter member 120 is suitably operably secured to the screw shaft for rotation with the screw and shaft. This cutter 120 has a plurality of knives, arms or blades 126 thereon extending from a hub portion thereof. These blades 126 each have a sharp cutting edge 130 formed thereon. Cutter 120 is shown only schematically but will in practice be a cutter embodying the invention.

In positioning the cutter 120 in the appa ratus, normally the flat surfaces 134 of the individual blades of the cutter member are flush against a flat surface of an associated cutter disc 136. This disc 136 is made from a low friction plastics material, such as nylon or other equivalent plastics that is relatively rigid and has low friction properties. The disc 136 has a plurality of cutting apertures or bores 138 extending therethrough so as to facilitate cutting and discharge of the meat being forced through the meat cutting and grinding device of the invention. These bores 138, in association with the cutting edges 130 of the driven blades provide a good, low friction cutting action on the meat being processed.

Retention of the plastics cutter disc 136 in the apparatus is facilitated by the provision of a metal carrier disc 140. This carrier disc has a recess 142 in one face surface thereof in which the plastics disc 136 is received. The carrier disc 140 also has axially extending bores 144 formed therein with such bores being aligned with the bores or holes 138, but which are slightly larger in diameter than the bores 138 for flow of the cut meat therethrough as it is discharged from the apparatus.

The plastics disc 136 and the carrier disc 140 both have center bores formed therein through which the shaft 122 extends for support thereof. A suitable cap 146 or other conventional means may engage an end portion of this shaft 122.

The carrier disc 140 is secured in position in engagement with the tubular frame of the apparatus, as by a lock ring 148. This lock ring 148 has a radially inwardly extending edge flange 150 that engages the periphery of the metal carrier disc 140 and forces it axially of the tubular frame 112. When the lock ring 148 is tightened, usually the carrier disc 140 seats against a shoulder 152 provided in the frame at the end thereof. The plastics disc 136 also may engage this shoulder 152 and in all events, it is snugly held in place when the lock ring 148 is tightened, and the disc is suitably retained in position in use of the apparatus.

In order to avoid rotation of the plastics disc 136 with relation to the carrier disc 140, there are a plurality of circumferentially spaced studs 154 provided on and protruding from the disc 140 for seating in holes 156 provided in one face of the disc 136 and only extending partially therethrough.

In assembly of the lock ring 148, the construction and arrangement of the apparatus of the invention is such that this lock ring can be used to maintain the discs 136 and 140 in good operative positions, and be secured against rotation in use.

A modified cutter blade 210 is shown in Figs. 10, 11 and 12. Its blades are preferably of the general cross sectional shape as shown for other blades such as the blade of Fig. 7.

However, in this instance, a flat surface 212 is formed on the portion of this blade adjacent the extrusion disc and it has a plurality of diagonally extending recesses 214 formed therein in parallel relation to each other. The recesses 214 are shown extending into the cutter blade about 1/8th inch. The recesses are provided at an angle of about 70" to a straight line forming the front or cutting edge 215 of this cutter knife 210. It should be noted that cutting sections are provided on the edge 215 between the recesses 214.Sharp cutting edges 216 are also provided where edge walls of the recess interesect or connect to the flat surface 212 and they extend slantingly with respect to a radius of the blade a sufficient distance so as to operatively overlap the adjacent recess and its similar cutting edge 216 whereby a plurality of cutting surfaces are provided on this blade. Normally the edges 215 and 216 of the blades are quite sharp. By the plurality of individual cutting and slicing actions provided by the plurality of cutting surfaces on the blade 110, an effective tearing, shredding and slicing action is provided on the meat for effective cutting and extrusion thereof.

The individual blades on the cutter 210 have inwardly slanted beveled arcuate or flat leading surfaces 218 thereon to aid in forcing meat towards the outer plate, and in cutting the meat. The surfaces 218 smoothly connect a leading overhanging edge 220 to the sharp cutting edge 215.

WHAT WE CLAIM IS: 1. A rotary cutter for a meat cutting and/ or extruding device including an apertured flat-faced discharge means, said cutter comprising a plurality of cutter blades extending substantially radially from an axis of rotation, each of said cutter blades having a flat bearing surface, said flat surfaces substantially lying in a common plane perpendicular to said axis, and including a cutting edge at the foremost portion of said surface for an intended direction of rotation and a leading edge axially spaced from and in advance of said cutting edge, said leading and cutting edges being connected by a smooth continuous surface extending forwardly in the direction of rotation from said cutting edge to the leading edge.

2. A rotary cutter as claimed in claim 1 wherein said continuous surface is a smoothly curved concave surface.

3. A rotary cutter as claimed in claim 1 wherein said continuous surface is substantially flat.

4. A rotary cutter as claimed in claim 1, 2 or 3 and including a radially extending slot in each of said flat bearing surfaces forming a second cutting edge on each said cutter blade.

5. A rotary cutter as claimed in claim 4 wherein said cutting edges are parallel and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

ratus, normally the flat surfaces 134 of the individual blades of the cutter member are flush against a flat surface of an associated cutter disc 136. This disc 136 is made from a low friction plastics material, such as nylon or other equivalent plastics that is relatively rigid and has low friction properties. The disc 136 has a plurality of cutting apertures or bores 138 extending therethrough so as to facilitate cutting and discharge of the meat being forced through the meat cutting and grinding device of the invention. These bores 138, in association with the cutting edges 130 of the driven blades provide a good, low friction cutting action on the meat being processed.

Retention of the plastics cutter disc 136 in the apparatus is facilitated by the provision of a metal carrier disc 140. This carrier disc has a recess 142 in one face surface thereof in which the plastics disc 136 is received. The carrier disc 140 also has axially extending bores 144 formed therein with such bores being aligned with the bores or holes 138, but which are slightly larger in diameter than the bores 138 for flow of the cut meat therethrough as it is discharged from the apparatus.

The plastics disc 136 and the carrier disc

140 both have center bores formed therein through which the shaft 122 extends for support thereof. A suitable cap 146 or other conventional means may engage an end portion of this shaft 122.

The carrier disc 140 is secured in position in engagement with the tubular frame of the apparatus, as by a lock ring 148. This lock ring 148 has a radially inwardly extending edge flange 150 that engages the periphery of the metal carrier disc 140 and forces it axially of the tubular frame 112. When the lock ring

148 is tightened, usually the carrier disc 140 seats against a shoulder 152 provided in the frame at the end thereof. The plastics disc

136 also may engage this shoulder 152 and in all events, it is snugly held in place when the lock ring 148 is tightened, and the disc is suitably retained in position in use of the apparatus.

In order to avoid rotation of the plastics disc 136 with relation to the carrier disc 140, there are a plurality of circumferentially spaced studs 154 provided on and protruding from the disc 140 for seating in holes 156 provided in one face of the disc 136 and only extending partially therethrough.

In assembly of the lock ring 148, the construction and arrangement of the apparatus of the invention is such that this lock ring can be used to maintain the discs 136 and 140 in good operative positions, and be secured against rotation in use.

A modified cutter blade 210 is shown in Figs. 10, 11 and 12. Its blades are preferably of the general cross sectional shape as shown for other blades such as the blade of Fig. 7.

However, in this instance, a flat surface 212 is formed on the portion of this blade adjacent the extrusion disc and it has a plurality of diagonally extending recesses 214 formed therein in parallel relation to each other. The recesses 214 are shown extending into the cutter blade about 1/8th inch. The recesses are provided at an angle of about 70" to a straight line forming the front or cutting edge 215 of this cutter knife 210. It should be noted that cutting sections are provided on the edge 215 between the recesses 214.Sharp cutting edges 216 are also provided where edge walls of the recess interesect or connect to the flat surface 212 and they extend slantingly with respect to a radius of the blade a sufficient distance so as to operatively overlap the adjacent recess and its similar cutting edge 216 whereby a plurality of cutting surfaces are provided on this blade. Normally the edges 215 and 216 of the blades are quite sharp. By the plurality of individual cutting and slicing actions provided by the plurality of cutting surfaces on the blade 110, an effective tearing, shredding and slicing action is provided on the meat for effective cutting and extrusion thereof.

The individual blades on the cutter 210 have inwardly slanted beveled arcuate or flat leading surfaces 218 thereon to aid in forcing meat towards the outer plate, and in cutting the meat. The surfaces 218 smoothly connect a leading overhanging edge 220 to the sharp cutting edge 215.

WHAT WE CLAIM IS: 1. A rotary cutter for a meat cutting and/ or extruding device including an apertured flat-faced discharge means, said cutter comprising a plurality of cutter blades extending substantially radially from an axis of rotation, each of said cutter blades having a flat bearing surface, said flat surfaces substantially lying in a common plane perpendicular to said axis, and including a cutting edge at the foremost portion of said surface for an intended direction of rotation and a leading edge axially spaced from and in advance of said cutting edge, said leading and cutting edges being connected by a smooth continuous surface extending forwardly in the direction of rotation from said cutting edge to the leading edge.
2. A rotary cutter as claimed in claim 1 wherein said continuous surface is a smoothly curved concave surface.
3. A rotary cutter as claimed in claim 1 wherein said continuous surface is substantially flat.
4. A rotary cutter as claimed in claim 1, 2 or 3 and including a radially extending slot in each of said flat bearing surfaces forming a second cutting edge on each said cutter blade.
5. A rotary cutter as claimed in claim 4 wherein said cutting edges are parallel and

said slot is adapted to collect bone chips therein.
6. A rotary cutter as claimed in any preceding claim, wherein said flat bearing surfaces terminate short of the axis of rotation.
7. A rotary cutter as claimed in any preceding claim, wherein radially spaced recesses are formed in the portion of each blade forming said leading edge.
8. A rotary cutter as claimed in claim 7, wherein said recesses extend circumferentially and are of maximum depth at the leading edge of each said blade.
9. A rotary cutter as claimed in any preceding claim, wherein each of said blades includes a plurality of slots or recesses formed in said flat bearing surface and extending from the front cutting edge thereof across said blade.
10. A rotary cutter as claimed in claim 9, wherein said slots are inclined to a radius at an angle less than a right angle and are spaced so that cutting edges formed by said slots operatively overlap.
11. A rotary cutter in accordance with claim 1 and substantially as hereinbefore described with reference to Figures 1 to 4, Figures 5, 6, or 7, or Figures 10 to 12 of the accompanying drawings.
12. A meat cutting and/or extruding device including a rotary cutter as claimed in any of the preceding claims.
13. A meat cutting and/or extruding device as claimed in claim 12 and including a driven screw extruder to which said rotary cutter is secured and wherein said discharge means includes an apertured disc formed from low-friction plastics material.
14. A meat cutting and/or extruding device as claimed in claim 12, wherein said discharge means comprises an apertured metal reinforcing disc and said apertured cutter disc of low-friction plastics material is positioned adjacent said cutter and parallel to said metal disc, the apertures in said metal and plastics discs being aligned.
15. A meat cutting and/or extruding device in accordance with any one of claims 12 to 14 and substantially as hereinbefore described with reference to Figures 8 and 9 of the accompanying drawings.