Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
1. Field of the invention
The invention relates to an apparatus for skinning
double fillets of fish, such as herrings, in particular
herings in a spiced, marinated or salted state.
When skinning double fillets it is important to
remove the extremely delicate skin from the fillets whilst
avoiding patches of skin and at the same time ensuring that
the fat strips sltuated under the skin on both sides of the
fin holders for the back fins are removed undamaged Erom the
fillets. The latter is desirable because there is otherwise
generally the danger that during the skinning the fat of the
fat strips is distributed over the skinned surface of the
fillets which leads to an impairment of the quality of the
latter.
2. Description of Prior Art
An apparatus for skinning double fillets of fish is
known from DE-AS 29 05 518, in which a pair of skinning knives
with an opening between them and with cutting edges
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- extending outwardly in the manner of a plough from points
situated adjacent the gap is associated with, and spaced
a small distance away fxom a conveying surface transporting
the double fillets on their skin s~de. Endless engagement
belts rotating synchronously with the conveying surface are
associated with the sides of the skinn.ing knives away from
the conveying surface on both sides of the opening.
When using this device it has been found that the conveying
engagement which occurs merely by frictional contact is by
no means sufficient to overcome the cutting or splitting
forces of the skinning tool and the frictional forces be-
tween the back surfaces of the skinning knives and the skin
or the fillet meat which increase as the skinning process
continues, so that during the course of the skinning the
double fillets often tend to stick and remain lying without
moving. It has further been found that this primarily
happens when the scraping knives have been advanced between
the fat strip of each fillet situated in the region of the
back fin edge of each fillet and its back meat through to
the skin and the skinning process has already begun.
OBJECT OF THE INVENTION
It is an essantial object of the invention to provide
for an apparatus for skinning double fillets of, in particular
fat fish such as herrings by means of which the skin of the
double fillets can be reliably removed whilst cutting free
the fat strips present on both sides of the fin holders of
the back fins.
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- BRIEF SUMMARY OF THE INVENTION
This object is achievea in accordanc~ with the present
invention by an apparatus for ~kinning double flllets of fish
such as herrings, the apparatus including a rotatingly driven
skinning roller having recesses distributed over its
periphery, a skinning knife having a cutting edge arranged
at a small distance from the periphery of the skinning
roller, a presser face arranged below the cutting edge
and defining with the periphery a gap along a part of the
latter, and rotatingly driven feed means having a ~eed
direction and defining a feed plane, the apparatus further
including a pre-severing device situated above the feed
plane, the pre-severing device including a pair of knives
extending essentially parallel to the feed direction, defininy
a gap between them and being essentially perpendicular to
the feed plane, the knives having cutting edges which are
directed towards the feed plane and approaching each other,
and a pair of peeling knives respectively colinear with
and following the knives to continue the gap and having
edges which are initially directed towards the feed plane
and change gradually into peeling edges which extend
outwardly a small distance above the feed plane.
The advantages achieved thereby reside in particular in the
fact that skinned individual fillets free from fat strips
and fat xemnants can be producted from the double fillets
by firstly severing, scraping resp. peeling ree the central
portion of the double fillet containing the fat strips and the
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- fin holders up to the skin and then subjecting the thus
prepared double fillet to the skinning by means of a skinning
apparatus operating in accordance with a known systPm with
a reliable feed so that in addition to the skinned fillets
also the cut free central portion of the double fillet
containing the fat strips and the fin holders of the back
fins are produced.
In accordance with a further embodiment of the apparatus
in accordance with the invention the knives may be construc-
ted as rotarily driven circular knives whose peripheral
cutting edges extend to the region of the conveyor surface,
but it is also possible to provide such circular knives
in addition to the knives upstream of these. Thus the
splitting forces may be maintained extremely low so that
the cutting, scraping or peeling free o the central portion
containing the fat strips and the fin holders proceeds without
damage to the delicate fillets, the knives only performing
a relatively small part of the cutting in when circular
kni~es are provided in addition to the knives.
Preferably a eed channel is arranged upstream of the
knives in the transfer directlon inclined to the conveying
surface, the feed cha~nel comprising side walls which are in
a V~shaped configuration and define a gap between them at
their lower edges, which gap i5 in alignment in the transfer
direction with the gap between the knives. Thus the fillet
halves of the double fillet to be ea to the skinning pxocess
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are deformed hack to approaching their natural position
with respect to one another, so that the double fillet
can be fed to the cutting edges of the knives o~ the pre-
severing device whilst exactly centrally aligned.
In order to ensure a reliable conveying during the
processing of the double fille~ in the precutting device
also in the case of dried out and thus stiff fillets, for
instance as a result of salting, expediently there may be
arranged a rotarily driven conveyor in the gap defined between
the knives, which conveyor has the same speed as that o the
conveying plane and comprises means form-sealingly, i.e.
positively engaging the double fillet to be conveyed.
Xn accordance with a further embodiment the conveyor may
comprise a spiked transport wheel, the tips of whose spikes
extend to the direct vicinity of the conveyor surface. This
provides the possibility of a positive transport o the double
fillet during its processing in the pre-peeliny device.
In accordance with yet a further embodiment the conveyor
may, in contrast to the aforementioned emhodiment, also
comprise an endless rotating chain or belt conveyor provided
with spikes engaging the double fillet, at least in the
reglon of the scraping or peeling knives. Due to the tension
which is thus exerted on the double fillet during its
processing in the pre-severing device the double fillet
is held tensioned so that a crushing up which disturbs
the operating sequence can not occur.
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Advantageously the conveyin~ or feed plane may
be formed by the end surfaces of closely adjacently positioned
protrusions between which the tips of the spikes penetrate.
Thus the tips of the spikes can pierce the skin of the double
fillet and so ensure that the latter is securely carried along
with them.
In order to guarantee the secure conveying engagement
with the skin which is only a few hundreths of a millimetre
thick during the skinning, the presser face may be held lightly
pressed by spring force against the rotating skinning roller.
BRIEF DESCRIPTION OF THE DRAWINGS
Other and further objects of the present invention
will be apparent rom the following description and claims
and are illustrated in the accompanying drawings, which, by
way of illustration, show preferred embodiments of the
present inventi~n and the principles thereof and what now
are considered to be the best modes contemplated for applying
these principles. Other embodiments of the invention
emhodying the same or equivalent principles may be used
and structural changes may be made as desired by those
skilled in the art without departing from the present in-
vention and the scope of the appended claims.
In the drawings
Fig. 1 shows an overall view of the skinning
machine in accordance with the invention
in axonometric representation,
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Fig. 2 shows a cross section throuyh the
pre severing or pre-peeling device
in the region of the knives in front
of the peeling knives,
Fig. 3 shows a cross section through the pre-
severing device ln the region of the
peeling knives, and
Fig. 4 shows a cross section through the
skinning roller with its associated
presser ~ace.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In a frame, which is not shown, of a skinning machine for
fish there is arranged a feed belt 1 rotarily driven by
suitable drive means and guided around a drive roller 2 and
a guide roller 3. A conveying surface or feed plane 4 of
this fe~d belt 1 can be formed by the end surfaces of closely
adjacently situated protrusions. In continuation o~ the end
of the feed belt 1 facing the drive roller 2 there is a
skinning device 5 which comprises a skinning roller 6 having
grooves 7 extending along its periphery from one end face
of it to the other.
Between the skinnin~ roller 6 and the point at which the
feed belt 1 changes direct~on there is situated a transfer
xoller 8 rotating at a speed faster than that of the
conveylng surface 4. Associated with the skinning roller 6 is
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a sk~nning knife 9 whose cutting edge lies in the vicinity
of the top or culmination line of the skinning roller 6. The
inner side of the cutting edge 10 continues into a concave
presser face 11 whose radius of curvature ~orresponds to
that of the periphery of the skinning rollar 6. The presser
face 11 of the skinning knife 9 is held against the periphery
of the skinning roller 6 by a slight spring pressure, The
cutting edge 10 of the skinning knife 9 is conveniently
provided with an inner bevel 12 of several tenths of a
millimetre. Above the conveying surface 4 and in the region
of the feed belt 1 there is provided pre-severing or pre-peeling
device 13 for double fillets 27 to be skinned. Upstream of this
pre-severing device 13 there is arranged a feed channel 24
for the double fillets 27 inclined to the conveying surface
4, the feed channel 24 comprising side walls 25 arranged in
a V-configuration with a gap 26 between them at their lower
edge 5~ The ends of the side wall~ 25 nearest the conveying
surface 4 are flattened out into a plane. This pre-severing
device 13 comprises a pair of knives 14 parallel to the
transfer direction of the feed belt 1 and perpendicular to
the conveying surface 4 between which knives 14 there is a
gap 15 aligned with the feed channel 24. The edges of the
knives 14 facing the conveying surface 4 are formed as cutting
edges 16 which gradually approach the latter. As an extension
of the knives 14 there is adjacent to them a pair of peeling
knives 17 between which the gap 15 is ~urther continued and the
edges of which, in continuation of the cutting edges 16
initially extend in a direction toward~ the conveying
surface 4 and gradually change into outwardly extending
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peeling edges 18 (Fig. 3), the latter extending spaced
a small distance above the conveying surface 4. Instead
of the rigidly arranged knives 14 or in addition to these
a pair of circular knives 19 can be used ~as depicted in
Fig. 1), xotated either mechanically or together with the
double fillet which is passed through beneath them, ad-
jacent to the peeling knives 17 either directly or in-
directly by placing the knives 14 in between. In the
gap 15 there can be arranged a rotatably driven conveyor
20, which has the same speed as the conveying surface 4
and which is con~tructed as a spiked transport wheel
or as a belt or chain conveyor 21 provided with spikes 22,
~he tips 23 of the spikes 22 extending to the immediate
vicinity of the conveying surface 4. If a feed belt 1
is used whose conv~ying surface 4 is constituted by
the end surfaces of closely adjacent protrusions the
tips 23 of the spikes 22 may mesh in with the conveying
surface 4. The conveyor 20 is con~eniently so arran~ed
that its conveying engagement first occurs between the
circular knives 19 or the knives 14.
The operat1on of the device is as follows:
A hand or machine filletted double illet 27, that is
a pair o fillets still adhering in the back region is
placed in the feed channel 24 with its skin downwards
and preferably wi~h its head end forwards. By virtue of
the V-shaped cross sectlon of the channel 24 the fillet
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halves are brought into a position somewhat app~oachin~
their nat-~ral relative position and thereby an aligning
effect is achieved which causes the edge of the back fin
to be gulded in the gap 26 at the bottom of th~ feed
channel 24. In ordex to improve the downward sliding of
the double fillet 27 in the feed channel 24 the surfaces
of its side walls 25 can be sprinkled with water. During
the downward sliding the double fillet 27 is spread out
whilst maintaining the guiding of ~he edge of the back
fin so that it comes onto the conveying surface 4 of the
feed conveyor 1 lying flat and aligned. The double fillet 27
thus reaches the circular knives 19 of the pre-severing
device 13 and is cut into by these on both sides of the
central portion 29 containing the fin holders of the back
fins up to the vicinity of the inner side of the skin 30.
During the further conveying the knives 14 which are
arranged approximately in the planes of the circular knives
19 enter the cuts which, by means of the cutting edges 16
directed towards the conveying surface 4 are deepened rlght
up to the inner side of the skin 30. In order to overcome
the cutting and frictional forces which occur the double
fillet 27 is conveyingly gripped by engagement of its
ce~tral portion 29 by the conveyor 20 arranged in the gap
15 between the knives 14 by virtue of the fact that the
tips 23 of the spikes 22 pierce it.
The double fillet 27 is ~hus fed to the peeling knives
17 connected to the knives 14 by virtue of frictlonal
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contact of its skin side with the conveying surface 4
and of form-sealing (positive~ contact of it8 central portion
29 with the conveyor 20. Thereby the peeling edges 18 of the
peeling knives 17 which gradually extend outwards and
constitute a continuation of the edges 16 of the knives
directly above the conveying surface 4 effect a peeling
free of the central portion 29 along the inner skin which
separates the muscle flesh of the fillet from the fat strips
situatea on both sides of the fin holders of the back fin
edge. Thus prepared, the double fillet 27 is fed to the
skinning device 5 which removes the skin 30 in a known manner.
In order to make the initlal cutting more reliable, the
cutting edge 10 of the skinning knife 9 is provided with a
bevel 12 of several tenths of a millimetre which simultaneously
promotes the retention of the so-called silver mirror on
the fillet. In order to ensure the difficult removal of the
skin which is only a few hundredths o~ a millimetre thick
the presser face 11 is held by a slight spring pressure
against the periphery of the skinning roller 6 providsd
with grooves 7~ As a result of this skinning process two
individual fillets 28, the central port~on 29 containing
the fat strips, and the skin 30 are obtained as separate
poxtions.
As already mentioned, the circular knives 19 may be
arrangad alone or ln addition to the knives 14, which
extend linearly. In the event that there are no circular
knives 19 at all, the knives 14 will be arranged so a~ to
take over their function completely.
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