Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a method of removing
the skin of double fillets, particularly of fish having thin,
frail skin, in that the skin between the fillet sides along the
dorsal fin is clamped in a conveyor device with the fillet sides
turned inside out, thus that its skin sides are facing each
other, and the fillet sides thus turned inside out being moved
against deskinniny knives, which separate the fillets from the
skin.
Skinning fish is a very nuanced problem as fish of
different species have dif~erent types of skin. The skin may be
more or less than and of different types, e.g. leathery, but also
the treatment of the fish, such as sub~ecting it to marinade,
salting, seasoning etcetera, is of big slgnificance for the
strength of the skin when it is stripped off the fillet.
From SE-C 202778 and SE-C 395343 are earlier known fish
processing machines wherein so called double fillets are freed
from the skin interconnecting the fillets. The machine in the
older one of these two patent publications is primar~ly designed
for filleting and skinning sprats, whereas that of the later
zo publication also shall be usable for bigger fish. None of these
known machines or other such machines, if it comes to that, in
practlce has been able to become successful on the market, as the
fillets either are not freed satisfactorlly from the skln or the
loss of flesh is too big. An important reason for that ought to
2S be that all hitherto know skinning machines are based on the
principle that the flesh shall be cut loose from the skin as
close to the skin as possible. As one flsh is not like the other
it i5 not possible even with the uttermost precision to guarantee
a satis~actory result, which has resulted in very high loss
percentage, which can not be accepted in view o~ the high raw
material price. In several cases lt can be sufficient that the
double fillet is not adequately located on the conveyor device,
whereby the dorsal fin will bs situated between the conveyor
device and
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the circular knives, resul-ting in that the passage o~ the skin is
prevented and the skin will burst.
It has also been tried to skin fillets after they have
been parted, bu-t then remains the problem that the fillets cannot
be fed automatically into the deskinning machine without requir
ing a manual and rather exact and therefore time wasting and
expensive feeding operation,
The present invention provides a me-thod and a device
for removing also very frail and thin skin, e.g. from herring,
whlch has ~ith the same advantages to skin raw fish as well as
treated fish, i.e. fillets that have been treated with marinade
or salted, pickled or treated otherwise. The present invention
effects the deskinning on one, hand in such a manner that the sil-
very membrane below the skin is malntained intact as far as pos-
sible and on the other hand thus that the aesthetically less
attractive black membrane is removed. It is furthermore possible
to effect the deskinning procedure at such a speed that it with-
out difficulties can be synchronized with conventional deguttingand filleting machines. Another important requirement is that
the rate of wastage may not exceed one or a few percents. In
accordance with the present invention the fillet sides are spaced
slightly from the conveyor device by means of spacing means situ-
ated imrnediately ad~acent the deskinning knives, the dorsal por-
tion of the double fillet is moved from the spacing means to the
inner side of the deskinning knives facing the conveyor device,
mainly without direction change, and the side portions o~ the
fillet sides, at the upper par-t of the spacing means and at least
nearest to the deskinnlng knives, are sub~ected to a successively
increasing directlon change in a direction away Erom the upper
edge of the spacing means, between the rear edge of the spacing
means and the bevelled edge of the deskinning knives, so tha-t the,
fillets are stripped from the skinr whereby the skin and any dor-
sal fins freely can pass a space between the desklnning knlvesand the conveyor device,
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Thus, according to the present invention there is pro-
vided a method for removing the skin of double fillets, in which
the skin along the ~orsal fin between t~e ~illet sides is clamped
in a conveyor device with the fillet sides turned inside out, so
tha-t its skin sides are facing each other, the fillet sides thus
turned inside out being moved against deskinning knives, which
separate the fillets from the skin, the fillet sides are spaced
slightl.y from the conveyor device by means of spacing means situ-
ated immedlately adjacent the deskinning knives, the dorsal por-
t~on of the double fillet is led from the spacing means to theinner si~e of the deskinning knives facing the conveyor device,
mainly wi-thout direction change, and the side portions of the
filled sides, at the upper part of the spacing means and at least
nearest to the deskinning knives, are sub;ected to a successively
increasing deflection movement in a direction from the upper edge
of the spacing means in a plane transverse to the direction of
movement of the fillets, ~etween the rear edge of the spacing
means and the rounded edge of the deskinning knives, so that the
fillets are stripped from the skin, whereby the skin and any dor-
sal fins ~reely can pass a space between the deskinning knivesand the conveyor device. Suitably water is poured over the cir-
cular deskinning knives which are driven at such a high speed
that a considerable friction reduction, by aquaplaning, is
obtained be-tween the knives and the skin.
According to the invention there is also provided a
device for performing the above-mentioned method including a con-
veyor shaped as a circular carrier plate equlpped wi-th means for
clamping the double fillets agains-t the circumference o the
plate r and circular deskinning knives situated on each side of
the carrier p:late ~ust opposite each other and in a manner
slightly overlapping said carrier plate, in which in front of
each deskinning knife, as seen in the transport directlon of the
carrier plate, there is provided a spacing means arranged to
space each fillet side from the flat side of the deskinning
knife, the deskinning knives have chamfered, blunt edges, at
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least a por-tion of the flat side of the spacing means facing away
from the carrier plate and si-tuated nearest to the deskinning
knives is bevelled in a direction towards the end edge of the
carrier pla-te, the spacing means with its rear edge turned
towards the deskinning knife has a shape mainly being complemen-
tary to the contour of the knife, the rear edge of the spacing
means ad~acent its upper bevelled portion has a mainly constant
distance to the carrier plate, and the deskinning knives are
arranged at some distance ~rom the carrier plate, so that skin
and dorsal ~in freely can pass between them. Suitably the spac-
ing means or the deskinning knives or both are laterally dis-
placeable relative to the carrler plate and the spaclng means
also are ad~ustable in their longitudinal direction.
15The present invention will be further illustrated by
way of the accompanying drawings, in which:-
Figure 1 sho~7s in side view the most important parts
constituting the deskinning device according to the invention;
Figure 2 is a section along line II-II in Figure l;
Figure 3 shows parts of the deskinning device in sec-
tion and the conveyor device with the spacing means in a view
from above;
Figures ~ and 5 are sections along lines IV-IV and V-V
respectively in Figure 1; and
30Figure 6 shows schematically a side view of the entlre
deskinning device according to the invention.
Referring to the accompanying drawings.
35The deskinning device according to the invention is a
development of the skin stripping device described in SE-A
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.r
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a40615s-7. Like this the deskinning device according to the pre-
sent invention comprises a conveyor device 11, incorporating a
carrier plate 12 driven by a not further shown motor and at its
circumference being equipped with a groove 13, in which is
arranged an encdless wire 14 or the like. The wire forms a fig-
ure-of-eight ancl is arranged over a sheeve 15, such as shown in
Figure 6.
From a transfer mechanism 16, which is only schema-ti-
cally intimated, the so-called double fillets 17 are transferred
onto the wire tha-t the fillets wlth their dorsal skin will be
hanging on the wire and with the flesh sides of the fillets fac-
ing each other. During the transport along the
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circumference of the carrier plate 12 towards lts upper part the
double fillets will become turned inside out thus that its skin
sides will be facing the carrier plate 12.
As shown more in detail in ~igurs 1, spaclng means 18
are arranged at -the upper portion of the carrier plate 12 at both
sides of the carrier plate 12 and one circular deskinning knife
19 is arranged behind the spacing means as seen in the transport
direction oE the carrier plate on each side oE the carrier plate,
which knives are driven by a not ~urther shown electric motor at
a considerably higher speed than the carrier plate 12. The
spacing means 18, which are fixed relative to the rotatable
carrier plate, are arranged ve~y near the carrier plate 12 and
with its upper edge in level with, or lower than the
circumference of the carrier plate. The rear end edge oE the
spacing means, which are facing the deskinning knives are
designed with a complementary shap~ mainly corresponding to the
contour of the circular knives, whereas the spacing means in
their upper portion is designed with a chamfer 20 facing the
outer edge of the carrier plate 12.
The chamfer 20 in the embodiment shown has been given
an extenslon over the entire length of the spacing means, which
is appropriate when fillets having no sharp changes are guided in
towards the deskinning knives 19. The only part o~ the chamEer
20, which is o~ vital lmportance to the very skinning operation,
ls however that situated nearest to the deskinning knives. A
portion 21 oE constant wall thickness ad~olns the chamfer 20 of
the spacing means 18, thus that it is obtained a steep change at
the rear edge of the ~pacing means in a direction towards the
rounded, blunt edge 23 o~ the deskinning knives. The circular
deskinning knives 19, which compared to earlier known knives oE
this type has a bigger diameter, are arranged at a di~tance A
from the carrier plate 12, which is so big that also thick skin
with appended dorsal Eins can pass between them.
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If the desklnning machine according to the invention
shall be used for different species of fish and/or fish of
varying size it is appropriate that the spacing means 18 and/or
-the deskinning knives 19 are ad~ustable laterally relative to the
carrier plate 12. The spacing mëans 18 should also be ad~ustable
longitudinally thus that the slot between lts rear edge 22 and
the edge 23 o~ the deskinning knlves can be ad~usted. As shown
in figure 2 of the drawings the chamfer 20 terminates at the
upper edge of the spacing means in a slightly rounded point 24~
which at one hand lies ln level with the circumferential end edge
25 of the carrier plate 12 and on the other hand is situated
inside the inner side 26 o~ the deskinning knives 19, such as
shown in figure 3. The distance B from the point 25 of the
chamfer 20 up to the inner side 26 of the circular knives is
chosen in view of the skin thickness of the fish and allows the
dorsal portion 27 of the double fillet to pass from the spacing
means 18 to the slot A between the lnner side 26 of the
deskinning knives and the flat side of the carrier plate 12,
mainly without direction change. It is thereby ascertained that
the skin portions around the dorsal portion of the fish without
disturbance can be led past the deskinnings knives without any
ruptures, even i~ the dorsal fin or fin bone of the fish should
lie wrong and be pulled into this passage.
At conventional deskinning machines it is tried to achieve that
the skin is sucked against the carrier plate thus that the
fillets will become firmly held when the flesh is cut loose from
the skin. According to the present invention there is supplied
at both sides o~ the deskinnlng knives 19, vla nozzles 28, so
much water at the same tlme as the deskinning knives are drlven
at such a hlgh speed, that a considerable friction reduction is
obtained particularly between the deskinning knives and the skin,
whlch friction reduction can be compared to a~uaplanlng. The
skin will be stripped from the fillets, due to the fact that the
deskinning knives have no cutting function and the separation of
the skin from the fillets is effected in that the skin is
sub~ected to an abrupt direction change over the rear edge 22 of
the spacing means 18. This stripping is effected so cautious
that the silvery membrane below the skin will remain on the
fillets mainly in uninterrupted extension. Some fish, e.g.
herring have a black membrane which is unaesthetical and shall be
removed, which according to the invention ls effected by the
distance B being adapted to the size of the fish. An increase of
the distance B means also an increase of the size of the slice of
flesh ~cut~ away at the passage of the double fillet past the
deskinning knives 19.
A gutted double fillet 17, where head and tail have
been cut off and the backbone with attached ventral ~ones have
been cut away and where the fillet sides are lnterconnected via
the dorsal skin of the fish only, is via the transfer device 1~
transferred to the movable wire 14 of the deskinning device, such
as shown in figure 6. The dorsal portion 27 of the double fillet
will be clamped between the wire 14 and the groove 13 of the
carrier plake 12, whereby the double fillet is firmly held in
longitudinal direction. At the rotation of the carrier plate the
double fillet will be ~onveyed along the circumference of the
plate, whereby the double fillet is turned inside ouk, thus that
the skin side of the fillet sides will be faclng the flat sides
of the carrier plate 12. The fillet sides will be spaced from
the carrier plate at the upper portion thereof by means of
spac~ng means 18, for being sub~ected to an abrupt direction
change at the rear edge of the spaclng means, said directlon
change being in the form of a Z-movemenk against the rounded edge
of the deskinning knives, whereby the fillets are slik away from
the skin. The fillets are collected in gutters 29 on both sides
of the carrier plate, whereas the skin is removed from the wire
by aid of an appropriate tool 30.
