Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROC~SS AND APPARATUS FOR T~E MEC~IANICAL SEPARATION OF
A COMBINATION OF MEATS AND BONE _ _ _
Fi~ld of the Invention
This invention is concer~ed with improvements in or
relating to processes and apparatus for the m~chanical separa,
tion of a combination of meat~ and bone.
Review of the Prior ~rt
The mechanical ~eparation of various meat and bone
combinations to produce a high quality meat produc~ fraction
is now a well-established industry. Some parts of the industry
use primarily the various parts of poultry, fish and red~meat
animals that would otherwise be di~cardedO owing to th~ high
cost of manual separation, but the separation of entire carcasses
- i~ al~o in some circumstances a viable commercial operation.
A number of different processes and apparatus have
been proposed hitherto for this purpose and as examples of
lS prior apparatus may be menticned those disclosed in U.S. Patent3
Nos. 3,396,768 (Kuribaia); 3,266,542 (Paoli); and 3,~39,994
~ tMcFarland). In a}l of ~hese machines a combination of mPat
~: and small pieces.of broken bone is forced under pressure
against a perfora~ed screen, the ~oft~r meat component being
20 ~ forced by the pressure through the ~creen~ while the more
rigid bone component is sw~pt along the face of the screen
without passing through, to a ~uitable discharge locationO
The resulting ractions are ~ubject to stxingent
.regulation by the a~propriate goyernment authoxiky and mus~
25 : meet minimum ~tandards as to, for exa~ple~
:; a) Maximum bone (calci~m) content in the ~eparated
meat.
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b) ~aximum temperature and temperatur~ rise to ..
~- which the separa~ad meat i~ ~ubjected.
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In addition to the~e yovernment applled standa~d~ ~
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the meat-processing industr~ which receiVes the ~oduct has
its own standards as to bone content, homogenit~, colour and
texture.
Defini:t:ion:o:f t:he ;Inve:nt:ion
It is an object of the invention to provide a new
apparatus for the mechanical separation of a meat and bone
combination.
In accordance with the present invention there is
provided apparatus for the mechanical separation of meat and
bone into separate fractions thereof comprising:
a) a cylindrical conduit having an inlet end and an
outlet end and containing a feed screw rotatable about a
longitudinal axis,
b) the feed screw comprising a plurality of successive
lands and upon rotation about its axis moving a meat and bone
combination to be separated along the conduit from the inlet
~: to the outlet end and applying radially outwardly operative
pressure to the combination pressing it against the conduit
wall,
c) at least part of the conduit wall comprising a
separator screen whereby the pressure of the combination against
the screen part forces the meat fraction through the screen
while the bone fraction is retained thereby and moved through
the conduit to the outlet end,
d) the said part of the conduit wall constituting the
separator screen comprising a plurality of plates and having
screen apertures in the form of elongated slots, the plates
having their inner edges constituting the inner conduit wall
.' and flexing under the effect of the said outwardly operative
pressure to facilitate passage of the meat fraction through
the screen slots while retaining the boney fraction on the said
inner wall.
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The term "meat" as used herein i~ intended to apply
to meat derived from an~ source in addition to that derived from
the conventional sources cattle, plgs.and poultry and, in
particular, is ihtended to apply to meat derived from fish,
crustacea, etc.
The ~erm "combination" as used herein i~ intended to
apply to a range of products extending from those consisting
predominantly of meat with some bon~ included, e.g~ whole
carcasses, to those consisting predominantly of bone with some
meat included, e.g. the bones resulting from hand deboning.
Description of the Drawin~s
Apparatus and a process which are particular preferred
: embodiments of ~he invention will now be described, by way of
example, with refer~nce to the accompanying diagrammatic
drawing, wherein:- .
Figure ~ is a plane cro~s section through the machine
taken on the axis of rotatio~ of the conveying separating and
: discharge ~crews, the upper half of the separating and discharge ~ :
screws being shown in cross-section for clarity o illustxation~
~20 while the lower halve~ of t~ese Bcrews are ~hown in ~ide
- : elevation,
Figure 2 i~ an end elevation o an annulu~ as u~ed
to ~orm the separating screen of th~ apparatus of Eigure 1, and
Figure 3 i~ a section taken on the l~:ne 3-3 o~
: Figure 20
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Description of the Preferred Embodiments
The apparatus of the invention comprises a base,
indicated generally by the reference 10, in which a drive
motor 12 is mounted. On the top of the base is mounted a ca -
.5 ing 14 having a tubular extension 16, the casing providing ahopper 18 for the reoeption of the meat and bone combination
to be separated. The casing 14 and extension 16 also provid~
a conduit 20 having mounted therein a conveyor screw 22, the
screw being rotatable about a horizontal lo~gitudinal axi~
A-A. The rear end of the screw 22 i~ splined and i~ in rota-
tional drivlng engagemen~ wi~h a splined boss 24 mounted in the
casing by bearings 26; seals 28 are also provided. This boss
is constituted by the free end of the output shaft 30 of a speed
reduction gear 32, the input to the speed reduction gear bein~
via a belt drive 34 from the drive motor 12.
This conveyor screw 22 is of conventional form and
the diameter of i~ body increa es progressively from the
inlet provided by the hopper into the extension while the radial .
: depth of it~ lands decreases correspondingly to maintain a con-
~ 2 stant external diameter for the whole screw; the pitch of the
: screw between successive lands also ~ecreases progres~ively,
~ with the result that the meat and bone combination is forced
; ~ ~ into the tubular extension and ~8 subjected therein to an in-
creasing pressure a~ it ~ravel~ along the conduit 20. Th~ :
pressurizcd combin~tion ~s fcd through a tapered annular outlet
: 36 of decrc.~sing diamntcr in ~ho dircction o~ flow formed by
inner taper~d~surface 38 o ~n annular part 40 fastened to
: the extension 20
A separator ~cxeen indica~ed g2nerally by ref~renc~
. 30: 42:coop~rate~ wlth a separat~ng s~rew m~mber 44 mounted in
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bore or conduit 46 therein to separate into different fraction~
the pressurized combination o~ meat and bone fed thereto by the
screw 22. The separator scr~en is to be described in detail
below, and in this embodiment is constituted by a large numher
of annular discs 48 (Fig. 2~, which are clamped tightly face-to-
face b-~ a set of circumferentially-spaced longitudinal tie-rods
50 extending between the part 40 and an axially~spaced tubular
part 52. Another tubular part 54 is slidable within a bore 56
in the par~ 52 and is embraced by a cap nu~ 58 ~ha~ is screw-
threadPd on to the free end of the part 52. The end of the part54 within the bore 56 is provided with a tapered fare 60
cooperatîng with a tapered face at the adjacent end of the screw
member 44 to constitute a throttle con~r~lling the pressure that
is applied ~o the separating meat and bone within ~he cylindrical
conduit 46.
The separating screw 44 has integral thexewith a
discharge screw 64 which rotates within a bore ~6 in the part 54,
~ ` the other end of the screw 64 being carried by a bearing 68.
: In operation~ the meat and bone combination, which may
comprise, for example, the otherwise~discarded necks and backs
of broiler chickens, iQ fed continuously to the hopper 16 and
passed by the screw 22 ~hrough the conduit 20 and under pressure
~: to the interior of the conduit 4~. Under the special action of
the separating screw member 44, to be described belowj the
2S combination is pressed out~ardly-against the cylindrical in~8rior ,
surface 70 of the separator screen 4~. The so~ter meat fraction
passes radiaily ou~wards through the screen and î~ collected in
a suitable receptacle 72~ while the more rigid bone, sinew, etc.
raction is carried along by the screw member 44 wi~hin the
~: 30 bore 46 until it~ i~ di~charged through ~he throttle opening 66
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in the part 54. The bone etc. fraction i5 then moved by the
discharge screw 64 through the bore 66 to an outl~t 74, where it
is collected in a separate receptacle (not shown).
The separated meat fraction is found to have a
markedly different physical structure from that produced by
any of the machines at present known ~o U8, and may be dis-
tinguished therefrom as being more coherent and not emulsified~
with greater retention of the longitudinal fibrous structure
characteristic of animal muscle tissue. It is beliaved at
present that this difference in physical structure is due to
the new manner in which the separator screw member 44 presents
the pressurized meat and bone to the separator screen 42 t and
also to the new manner in which the screen is operative to
separate ~he meat and bone fractions.
The screw 44 comprises a plurality of successive lands;
and the pitch of ths lands decreases progressively along its
, length to compensate for the loss of separated mea~ produc~
; - through the separator screen, and so that the pressure applied
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to the meat and bone combination within the bore 46 is maintained
within predetermined limits. Each land of the helix is shaped
to have its rear face concave and i~ arranged to direct the
combination radially outwards, while the front face of each
land is shaped ko direct material it engage~ radially inwards
toward the screw axis. Thi~ special land shape ~herefore
~ ~S crea~es between each immëdlately successive pair of leading
and trailing lands an elliptical movement o~ the material, with
- the material stationary or relatively so while it is in contact
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with the inner face of the separator screenO Thi~ movemen~, as
indicated by ~he arrow~ 76~ i~ radially ou~wards adjac~n~ the
.~ .
30 leading land~ radially lnward adjacent the t3:ailing land~ and
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forward rom the trailing land to the leadin~ land adjacent the
screw body, and is superimposed upon the general movement of
the material lengthwise of the screw toward the outlet 56.
Another way of describing the motion is that the material i5
"peeled" from the surface of the separator sereen by.the leading
face of the trailing land, and is then "tucked under" the
material already against the separator screen in its movement
~` in the direction of flow. While this movement is happening
there is a cons~ant pre~sure radially outward upon the material.
This particular circulation, in which the part of the material
in contact with the separator screen is stationary or at least
relatively so, is believed to be a principal factor in the
performance of the process and the apparatus. Thus, the
material is forced under the radially outwardly opera~ive
.pressure applied thereto against the screen with the minimum
amount of shearing along ~he screen innex surface, and i~ is
believed tha~ it is this shearing~which is responsible for
: : ~ many undesirable effects of prior mechanical separating
: ~ :processes and apparatus.
; 20 ~ The dif~erences in ph~sisal structure between the
separated meat product of the apparatus and process of this
invention shows t~at inherently a differen~ separating process
is involved. Owing to the special movement of the material
there is no oppor~unity for the accumulation o~ particl~ of
.25 :bone against t~e inner sur~ace o~ the separatox screen. The
meat tissue separates ~rom the bone and flow~ through the slots
in the ~orm of relatively long thin shee~s, as compared to the
"particlen emulsion or slurry structure obtained with prior
- apparatu~ and processes. ~nother beneficial effect which i~
30 ~ believed to~ low from thi~ minimizat~on of ~hearing in the
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direction of flow is the xPduction of bone slivers in the meat
fraction. It is ~ound with our new process and apparatuR that
the temperature increase in the product in passing t~rough the
machine can be held to below the limits set by most authorities.
S This smaller temperature increase ha~ a number of beneficial
effects:~
a) There is no requiremen~ for the pre-cooling of
the pxoduct below the temperature at which it i~ in any case
normally stored or transported.
b) A machine of given size can be operated harder
with a greater throughput o~ product withou~ exceeding the
specified temperature lLmit~ ,.
: . c) A reduced consumption o~ energy causèd by friction
is evidenced by the lower temperature rise.
d) A sharp temperature increase is evidence of
strong forces applied to khe mixture and is believed to be
accompanied by damage ~o the cell s~ructure that permits rapid
dehydration of the resulting meat product; the meat product
of the invention shows a reduced tendenGy ~o subsequent
. 20 dehydration and leaching.
: ~ Referring now especially to Figure 2 of ~he drawings,
the separator screen o~ the inven~ion is made of a large number
of annular plates or discs 48, on~ of which is illu~trated
by the Figure. It will be seen that each plate ha~ an inner
~; 25 cylindrical fac~ 78 ~orming the bors 46, while the outer faca
has a number of protrusions 80, each of which has a bore 82
therein for the passage of a respectiv~ locating s~ud 84
engaged in the members 40 and 52~ The parts 86 of the ring
~ on one side between each ~wo ~mmedia~ely adjacent protrusions
: 30 70 are removed, 80 ~hat the clamping of the ring~ face~to ~ace
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leaves a ceries of thin circumferential slot~ through which
the meat component flows to separate from the bone component,
which moves through the bore to the outlet. Small portions 88
of the parts 86 are left to provide corresponding ~pacing
elements, which will accurately maintain the axial ~pacing o
the slots 76.
It has b~en found that the rigidity or flexibility
of the rings is of impoxtance in obtaining a sa~isfactory
separating action. If t~e rings are too flexible the proportion
of the bone to the meat fraction increases and bone slivers pas
through, while if they are too rigid the meat content of the
bone frac~ion immediately is increased and higher pressures
: must then be employed to obtain an acceptable separation,
resulting in higher temperature rises, even with our improved
. 15 process. Moreover, wi~h plate~ that are too rigid the
desirable fibrous structure is more diffiCult or even Lmpossible
to obtain.
It is known ~o those skilled in the art of mechanical
meat and bone separation that apertures of about 0.02 inch
: 20 (0.05 cm~ are required in the separating screen for adequate
bone retention, and this is the usual ~pacing employed for the
circumferential ~lots 76. However, the ~lexing that is possible
in the plates of ~he apparatus of ~he invention appears to be .
highly beneficial for reasons which are not yet fully evident.
It is believed at present that ~he flexing may permit ~he
passage of the "sheets" of fibrous tissue through the somewhat
enlarged spaces, while closing down the immediately adjacent
slo~s sQmewhat to provide better bone retention. I~ will be
apparent that this effect ~annot be achieved with the
3 0 perforated ~creen~ that have been employed hither~o, compri~ing
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a large number of closely sp.~ced holes, since there is no wa~
in which a hole can flex to any great extent to open further
with a converse effect upon lmmediately adjacent holes.
The equivalent effect could therefore be achieved
by the provision of a separator screen constituted by a large
number of longitudinally disposed strips placed face-to faca,
with longitudinal slots between them.
The annular discs or plat~s 48 may be fo~med from
. stainless steel alloy sheets ~alloy 303 or 304) of thick~ess
.060-.125 inch (0.1S-0.32 cm~. The par~s 86 may be mi}led to
a depth o~ 0 . 015-0 . 02 in¢h (0. 037-û . OS rm) .
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