Cutter assembly for meat grinder

The invention relates to a cutter assembly for use in a meat grinder which consists of a disc perforated by bores of diameters which vary over the length of the bores thereby to provide dwell and massage zones and a rotatable knife in sliding engagement with one of the surfaces of the disc, the knife consisting of a peripheral ring and a hub with a plurality of evenly spaced first knife blades extending from the ring toward the hub, a plurality of evenly spaced second knife blades extending from the hub toward the ring, and a plurality of evenly spaced third knife blades extending from the hub to the ring, the knife blades forming between them cutting zones. The configuration of the perforations and the knife blades ensures cutting raw materials into particles of uniform size.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention, in general, relates to a cutter assembly and, more 
particularly, to a combination of a perforated disc and a knife for use in 
meat grinders or similar diminution machinery provided with feed screws or 
augers rotatably mounted in a pressure housing and with single or 
multiple-component cutter sets. 
2. The Prior Art 
In its simplest form, a cutter set for meat grinders is made up of a 
perforated disc rigidly mounted in the cutter housing of the meat grinder 
and of a knife associated with the perforated disc and rotatably driven by 
the feed auger provided with an axial stub for receiving the knife. An 
arrangement of a plurality of knives and perforated discs constitutes a 
multiple-component cutter assembly. 
During rotation of the knives, their cutting edges move over the surfaces 
of the perforated discs to chop the material advanced against the surfaces 
of the perforated disc facing the interior of the housing or, in the 
event, the flow of the material. The perforations in the discs are 
fabricated in various ways and, depending upon their disposition in the 
surface of the disc, they participate in the acceptance and movement of 
the material. The reason for this is that the perforations or bores are 
distributed over the entire surface of a disc, arranged in different 
coordinates and disposed in different ways relative to the arms of the 
knives. The different dispositions and different pressure build-up in the 
raw material lead to different feed processes in individual perforations 
or segments of a perforated disc. 
The state of the art is replete with perforated discs and rotary knives 
used in such cutter assemblies. The perforated discs serve not only to 
receive within their perforations the material being processed, but also 
to compact and support the material, their edges functioning as counter 
blades for the rotating knife to accomplish the cutting or chopping 
action. 
To function as counter blades the perforated discs are made from tool and 
other high-quality steels of a Rockwell C hardness of between about 50 and 
about 62. Moreover, the selected material, the perforation density and the 
number of perforations in a given disc are of the utmost importance as 
regards the rate of feed of material through the disc, and they bear upon 
the quality of the entire cutting assembly. 
Hitherto, perforated discs have been made to provide a plurality of 
perforations constituting bores with little resistance to material 
feeding, care being always taken to ensure disposition of these 
perforations such that they provide sharp edges relative to the surface of 
the disc and to provide a high-grade surface smoothness to interfere as 
little as possible with the feeding of the material through the 
perforations. 
Thus, German Patent DD 277,399 relates to the problem of an optimum 
perforation density in a disc. As disclosed, the surface ratio between 
perforated and non-perforated areas is between 0.2 and 0.3, the density is 
between &lt;60 and 80%. The connected surface portions are said to constitute 
a system of secondary cutting edges, and the width of a perforated disc 
structured in this manner is to be in certain proportion to the diameters 
of the perforations. The width of perforated discs structured in this 
manner is to between about 0.125 to about 0.25 times the diameter of the 
bores. 
German Patents 3,821,930 and 4,338,347 relate to the material of perforated 
discs relative to mechanical processing and to its matching with a given 
knife. In particular, German Patent 3,821,930 describes a meat grinder the 
perforated disc and knives of which are covered by a ceramic coating. 
Suitable ceramic materials are aluminum oxide (Al.sub.2 O.sub.3), 
zirconium oxide (ZO.sub.2), silicon carbide (SiC) or mixtures of such 
materials. 
With a view to reducing the technical complexity of the manufacture and its 
costs, German patent 4,338,347 discloses a perforated disc for meat 
grinder cutter sets made of grey cast iron, preferably spheroidal graphite 
cast iron or laminar cast iron with a Rockwell C hardness between about 25 
and 28. 
All perforated discs hitherto known have been structured in the mentioned 
manner, care having always been taken to ensure the perforations are as 
sharpedged as possible and that the wall surfaces of the perforations were 
as smooth as possible for feeding the material through the disc 
perforations substantially without interference. This has been found to be 
disadvantageous, however, because the material could only be fed through 
the perforations, always in as straight a feed direction through the 
perforated disc and cutter set as possible. This does not, however, 
positively affect the cohesion of the material being chopped. 
A further disadvantage of known knives and perforated discs is the 
different cutting sequences which leads to particles or grains of 
different sizes within the perforations of the disc and, hence, to 
different levels of pressures pressure in given areas of the perforated 
disc. 
OBJECTS OF THE INVENTION 
It is an object of the invention to provide perforated discs and knives for 
cutter sets of meat grinders of reduced cost and complexity as regards the 
manufacture of the perforated discs. 
Another object of the invention is to provide a perforated disc providing 
increased dwell time of the material within the perforations. 
It is also an object of the invention to provide a perforated disc of the 
kind referred to which provides for improved cohesion of the material by 
deflection of its cross section. 
Yet another object of the invention is to provide a perforated disc of the 
kind referred to which provides for improved cohesion of the material by 
changing its cross section. 
Still another object of the invention is to provide a perforated disc and 
knife assembly for meat grinders ensuring uniform size of the chopped 
pieces of material. 
Other objects will in part be obvious and will in part appear hereinafter. 
BRIEF SUMMARY OF THE INVENTION 
In accordance with a currently preferred embodiment of the invention there 
is provided an assembly consisting of a rotatably driveable knife provided 
with hanging, standing or uninterrupted blades and of a perforated disc 
provided with stepped perforations of different diameters and divided into 
a dwell zone and a massage zone, the perforations being disposed in 
parallel relationship to the axis of the perforated disc. 
In contrast to hitherto known perforated discs, the perforations of the 
disc in one embodiment of the invention are of stepped configuration. In 
another embodiment the perforations are provided with a shoulder or neck. 
The material to be fed through the perforated disc is retained at these 
steps or shoulders and is rolled, kneaded or rotated before it is ejected 
from the perforation. As a result of this action, the material assumes a 
state of enhanced cohesion and improved water absorbency 
In accordance with another preferred embodiment of the invention, the 
blades or arms of the knives are of different configurations. They may be 
uninterrupted knife arms extending from a peripheral ring to the hub of 
the knife, or they may be hanging or standing blades extending from a 
peripheral ring in the direction of the hub or extending radially from the 
hub to the peripheral ring. Combinations of hanging and standing blades 
are also possible. A knife may consist of three or four evenly spaced 
blades or arms providing between them equally sized cutting zones. 
The particle size of the chopped material is determined by the shape of the 
knife blades and by the length of time the material penetrated into a 
given perforation is exposed to the blade. 
Structure and disposition of the perforations in the disc, the 
configuration of the knives as well as the matching between knives and 
disc result in a certain cooperative relationship and provide for 
effective spacings of the knife blades relative to a given number of 
perforations of the disc within the effective range of the knife blades. 
Hence, there are equal spacings between individual knife blades and 
perforations as well as an equal number of perforations in individual 
cutting zones. This ensures equally sized chopped material particles and 
homogenous processing conditions as a result of the effect the internal 
configuration has upon the material. 
In accordance with a further advantageous embodiment of the invention, the 
perforations in a disc may be of different cross-sectional configurations. 
The perforations are arranged within the surface of a disc such that their 
number and spacing are identical in each cutting zone. The perforations 
may be of circular or other cross-sectional configuration such as, for 
instance, square or polygonal. 
Preferably, the perforations are not smooth and uninterrupted but stepped 
to provide different cross-sections disposed such that there is an equal 
number of such perforations at a defined spacing from the knife blades. 
The perforations may be configured to have one or more shoulders or 
strictures intermittently reducing the diameter of a perforation in the 
direction of its output end. In another configuration, the perforations 
may have relatively wide openings at both ends with an intermediate 
stricture. 
In a further advantageous embodiment of the invention, the perforations may 
be formed by two radially offset sections. 
Proper selection of the diameter of the perforations causes the surfaces of 
a chopped particles to be roughened, massaged and rubbed upon entering the 
perforation, whereas the zonal arrangement of knife blades results in a 
uniform particle size thus increasing the cohesion and absorbency of the 
chopped material. Other advantages derived from the invention are improved 
quality of the final product and reduced processing time.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Perforated discs 1 of the kind useful in the context of the present 
invention are of a basic structure similar to well-known discs of this 
kind and consist of a body member 2 provided with a center bore 3 for 
rotatably receiving an axial stud of a feed auger (not shown). As will be 
described hereinafter, knives in accordance with the invention may be 
provided with a plurality of blades disposed at a given spacing from each 
other. 
The front and rear surfaces 9, 10 of the perforated discs are planar 
surfaces disposed in parallel to each other, the front surface 9 facing 
the material to be chopped (not shown) and constituting a sliding surface 
for a rotating knife. The rear surface 10 is the output surface of the 
disc 1. As may be seen from FIG. 1, the disc 1 is provided with 
perforations 4 disposed parallel to the axis of the center bore 3. The 
blades of the knives 15 shown in FIGS. 5 and 6 form zonal knife spacing 
systems, sometimes referred herein as cutting zone 16, which lead to 
chopped material particles of uniform size. 
As may also be seen in FIG. 1, the perforations 4 are of stepped 
configuration forming intake ends or sections 5 and output ends or 
sections 7 of different diameters, with a tapered shoulder or stricture 
being formed intermediate the intake and output ends to provide for a 
change in the flow of raw material. As shown in FIG. 1, the diameter 
D.sub.1 of the intake end 5 is larger that the diameter D.sub.2 of the 
output end 7. The tapered shoulder constitutes a massaging zone 12 where 
the material is kneaded, rolled or otherwise physically rearranged. A 
dwell zone L1 for temporarily retaining particles of chopped material is 
disposed ahead of the massaging zone 12. The size of the particles is 
determined by the cutting zones 16 (see FIG. 7). 
The functional relationship between the input end 5 of the perforations 4 
and the output end 7 and knife arm system or cutting zone 16 is determined 
by the geometric dimensions of the perforations 4. As shown in FIG. 2, the 
perforations 4 are segregated into an intake section 5, an intermediate 
section 6 and an output section 7. The longitudinal extent of the dwell 
zones 21 and of the massage zones 12 is a function of the diameters of 
those sections. 
Thus, the length of the dwell zone L1 of the perforated disc 1 shown in 
FIG. 1 is thrice or four times the diameter of the input section 5 and the 
overall width of the perforated disc 1 is determined by the ratio of 5 to 
6 times 
##EQU1## 
wherein D.sub.3 =the diameter of the output section 7; 
D.sub.2 =the diameter of the intermediate section 6; 
D.sub.1 =the diameter of the intake section 5. 
The perforation 4 of the perforated disc 1 schematically shown in FIG. 2 
has multiple steps. The disc 4 may be called a "massaging disc" because of 
its plurality of transitional sections. The perforations 4 of this 
embodiment are divided into an intake section 5, an intermediate section 
6, and an output section 7. In this embodiment the dwell zone 11 is 
located in the longitudinal extent of the intermediate section 7 and may 
be derived from the ratio of 1 to 2 times the diameter D.sub.2 of the 
intermediate section 6. 
The direct relationship between the diameters of the intake sections 5 and 
the output section 7 is in the range of from about 0.5 to about 0.95, 
whereas the lengths of the dwell zones, relative to the same diameters of 
the intake and output sections, are about once or twice or, depending upon 
the extent of the desired mixing and massaging of the raw material, thrice 
to four times the diameter of the intake or output sections 5, 7. 
Further embodiments of perforated discs are shown in FIGS. 3 and 4. As 
shown in FIG. 3 the intake section 5 is radially offset from the output 
section 7, with a shoulder 13 being formed between the two sections to 
provide a dwell zone 11 and a massage zone 12. The diameters of the intake 
and output sections 5, 7 are identical. 
The embodiment of FIG. 3 lends itself to efficient manufacturing techniques 
by axially offset bore being sunk into the front and rear surfaces 9 and 
10 of the disc 4. 
In accordance with FIG. 4 the diameters of intake section 5 and output 
section 7 are identical. A stricture is formed by a bore 14 of reduced 
diameter extending between the intake and output sections. A dwell zone is 
created at the transition between the intake and output sections. 
Advantageously, perforated discs 1 in accordance with the invention will be 
arranged in pairs. That is to say, one or more perforated discs 1 are 
arranged in succession on the axial stud of a feed auger. In this manner, 
the dwell times of the raw material to be chopped may be altered. An 
arrangement including a plurality of perforated discs 1 is particularly 
useful where dwell and massage times are to be adjusted in relation to the 
raw material to be chopped. 
Advantageously, the perforated discs 1 in accordance with the invention are 
heat-treated such that their front and rear surfaces are of different 
hardness. Preferably, the front surfaces 9 engaged by rotating knives will 
be harder than the rear surfaces. 
A particular advantage derived from perforated discs made in accordance 
with the teachings of the instant invention is that the structure of the 
transitions in the stepped perforations 4, i.e., the intake section 5, the 
intermediate section 6 (if provided) and the output section 7, leads to 
the provision of congesting, massaging and friction systems which subject 
the material pressed through the perforations, such as meat, to kneading, 
rolling and friction to improve its cohesion and, thus, its water 
absorbency. This, in turn, results in a higher quality of the end product. 
Whereas the structure and configuration of the perforations 4 in the discs 
1 substantially improve mixing and cohesion of the material being 
processed, the knives 15 cooperating with the discs serve to chop the 
material penetrated into the perforations into particles of uniform size. 
To this end, the knives are structured as hanging blades 17, standing 
blades 18 or uninterrupted blades 19. As herein defined, a hanging blade 
17 is mounted on a peripheral ring and extends centripetally toward the 
hub of the knife. A standing blade 18 will be understood to be a blade 
extending from the hub of a knife toward the peripheral ring. 
Uninterrupted blades 19 are those extending from the hub to the ring. 
Uniformity of the particles size is accomplished by the knives being 
structured in the manner described above and shown in FIGS. 5 and 6, with 
their blades 17, 18, and 19 being disposed at a predetermined distance 
from each other. 
FIG. 7 depicts the arrangement of a perforated disc 1 with an associated 
knife 15. Matching the disc 1 with the knife 15 will be seen to result in 
cutting zones 16. Also, the knives blades 17, 18, 19 will be seen to be 
uniformly spaced from each other. 
The arrangement of the blades 17, 18 and 19 of a knife 15 provides 
sufficient time to the material to penetrate into the perforations 4 of 
the disc 1 and to be chopped into particles of uniform size. It also 
ensures a uniform cutting action and, hence, uniform particle size, over 
the entire surface 9 of the disc 1, by simultaneous cutting at the outer 
and inner sections of the disc 1.