Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for skinning
fish fillets, comprising a rotatable skinning roller,
conveyor means for advancing the fillet to the skinning
roller and a skinning knife provided with a cutting edge
at a fixed distance from and a presser face equi-spaced
' rom the periphery of the skinning roller. :
.. : 2. Description of Prior Art
Known apparatus for skinning a fish fillet comprises
skinning rollers which are provided on their periphery with ~ . .
a uniform arrangement of teeth in which the faces of the
teeth lying in the circumference of the roller are very
~ narrow and the gaps between the teeth relatively large and
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.. 15 deep. To improve the running-in or entry of the skin of the
.l leadlng fish fillet end under the cutting edge of the skinning
~. knife, according to DE-OS 25 23 752 the skinning knife is
.i provided, at its cutting edge, with a surface directed away
from and against the rotational direction of the periphery of
the skinning roller.
:- Such apparatus has a number of advantages: ~hey have :-.
.` a simple construction, the drive for an oscillatlng skinning
. knife can be dispensed with and they make the removal of
the skin possible without loss of a tip of flesh at the
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leading end of the fish fillet. However, they also have
disadvantages: The yield of fish flesh attainable with such
` apparatus ls not satisfactory because the largest part of
the gain in f:Lsh flesh attained by the non-loss of the flesh
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~ tip at the preceding end of the fi~h fillet gets lost due to
the fact that a thicker layer of fish protein remains on
; the entire skin ~urface than is the case with skinning
. apparatus wi~h a switchable skinning knife. This not onl~
- 5 reduces the yield in fish meat, but also impairs khe
.. ~ appearance and the consistency of the skinned flsh fillets,
.~ b~cause maintenance of the silver layer with the protective
layer lying thereunder on the skin side of the fish fillet
i~ only attainable with dlfficulty or ~s even not obtainable
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at allO A further important defect of ~uch apparatus is that
fillet~ of fish with thick andJor scaly skin cannot be
~ skinned at all or at least not reliably, while the running-in
-~ of ~he skin below the cutting edge of the ~kinning knife
i8 not properly attalned even wlth a skinning knife (according
to DE-OS 25 23 752) provlded with a ~urface dlrected against
the circulating dlrection of the skinning roller.
. 3. Object of Invention
It is one of the main objects of the present invention
~: to avoid the disadvantages o~ said known ~kinning apparatus
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:~ 20 and to arrange the apparatus such that it enable~ the skinning
at high yleld of flsh flesh by leading the flllet to be skinned
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: ~o closely to the skinning kni~e that it is upset in front of
. the same and that even thick or scaly skin wi.ll run-in safely
underneath the cutting edge of the skinnin~ kni~e.
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, 25 SUMMARY OF T~E INVENTION
According to the present invention there is provided
an apparatus for skinning fi~h fillets, comprlsing a rotatable
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~ skinniny roller, conve~or means for advancing the fillet to
- the skinning roller~ and a skinning kni~e provided with a
cutting edge at a fixed distance from and a presser face equi-
spaced from the periphery of the skinning roller, wherein the
periphery of the skinning roller is provided with recess means
distributed over the circ~mference of said skinning roller and
extending from one end face of the latter to the opposite end
face and with lands enclosed between said recess means for
transporting the ~illet and supporting it at the skin side
thereof, each of the lands, when measured in the direction of
- the circumference of the skinning roller, having a width
whlch is a multiple of thè width of each of the recess means.
The main advantages th~s achieved are that the skin is uniformly
supported over the lands and that the yield in fish flesh is
increased due to a uniform silver mirror being attainable on
the fish fillet. Also the running-in of the skin of the pre-
ceding fish fillet end takes p~ace securely and without delay
with every kind of fish because it does not execute a vertically
;~ dancing motion which is caused by the teeth of the skinning
roller of known apparatus, but lies flush on the lands of the
skinning roller rotating under it so that thus the skin of
the preceding end of the fish fillet is enabled to penetrate
~ into one of the grooves and come below the cutting edge of
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the skinning knife.
The recess means may be grooves.
The conveyor means may comprise an endless belt, and a
rotatable transfer roller may be disposed between said belt
and said skinning roller, each of these elements known per se.
The grooves may extend axially of the skinning roller.
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:~ 30 Thereby~ the skinning roller can be easily manufactured.
The groove means rnay extend helically around-the skinning
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roller. This enables, in the case of narrow grooves, the
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engagement length for the skin to be enlarged.
The groove means may well comprise helical grooves
; which cross one another. Thereby the number of the engagement
'A~ locatlons of the skin may be incxeased.
The groove means be arranged in arrow shape. Thereby,
the flush resting of the skln on the lands of the roller may
be improved by the skin being outwardly stretched.
In order to make sure that for every fish fillet end
arriving a groove is ready, the groove means may be so
arxanged that for any angular posltion of the sklnning
roller at least part of the groove means is dlsposed
opposite the pres~er face.
Preferably the groove means may have a base which is
narrower than the mouth and may have opposite side walls which
lS taper toward~ each other from the mouth, the depth of the
groove means preferably being less than the least width
thereof. Thereby the space for the running-in of the skin
lets it~elf be dimensioned adequately without side effects
on the silver mirror taking place.
, 20 The lands of the skinning roller may be rough and
the roughness may be produced mechanically, chemically or
- el~ctrolyticàlly. The roughness provides a co-efflcient of
adequate for the entrainment of the skin without
endangering the yield of fish flesh.
The lands of the skinning roller may, however, also
be provlded with a fine toothing. Thereby, the skin of
fish ~illets with large ~kinning resistance can be
conveyed securely.
In the case of an arrangement of a transfer roller
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this may be provided wlth a fine toothing. Thereby further
quietening of the leading end of the fish fillet before its
running-in into the skinning knife i5 attainable.
A known par se presser rol:Ler may be disposed in proximity
of the cutting edge of the sklnning knife. Therehy, automatic
'~ checking or alignment of the preceding end of the fish fillet
and consequently the secure running-in thereof may be attained.
Advantageously a guide face may be arranged above the
skinning roller and at an acute angle with a tangent line
drawn from the cutting edge of the skinning knife to the
- clrcumference of the skinning roller, said guide face having
an edge adjacent the skinning roller which passes slightly
across the cutting edge of the skining knife~ l~es on the
back of the skinnlng knife and is arranged to yield ln an
lS upward direction. This enables the positive feeding and
; running-in of the leading fillet tips of the rather stiff
~ fillets even in case of rigor mortis into one of the ~rooves
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` between the lands and the safe separation of the fibres between
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; ~kin and fillets at the end of the skinning process.
To increase thie run-in eff0ct of very stiff illets
and to lmprove the skinning process even ~urther, the guide
faco may be pivotable about an axi~ parallel to the axis of
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the i~kinning roller and perform an oscillating movement of
8mall amiplitucle in the conveying direction of the fish
, 25 ~lllat~.
`;~ The trailing flanks of said groove means can be
- backwardly inclined opposite to the direction of rotation
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1 of the skinning roller. Thereby the safe initial cutting is
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further improved and the danger of patches o skin remaining
on the flesh avoided.
An embodiment of the present invention will now be more
parti~ularly described b~ way of example and with reference to
the accompanying drawing, the single igure of which shows an
axonometric ill~stration o two diEfering versions of an
apparatus embodying the present invention, the one version to
the right hand side of the feeding and conveying direc~ion
showing a g~ide face~ and the other one to the left incorporating
a pressure roller.
A deflecting roller 11, a transfer roller 3 and a skinning
roller 2 are jornalled in a fr,ame (not shown) and driven counter-
clockwise as shown by,the arrows on the periphery of the rollers.
An endless feed belt 1 is looped around the deflecting roller 11
and tensioned by a tensioning roller (not shown). ~he transfer
roller 3 and the skinning roller 2 each run at a higher peri-
pheral speed than the feed-be1t 1. A skinning knife 4 is
arranged fast with the frame above the upper half of the
skinning roller 2 and has a presser face 42 e~uidistantly from
the peripheral surface 21 of the skinning roller 2. The gap
between the cutting edge 41 or the presser face 42 and the peri-
pheral surface 21 of the skinning roller 2 is a few tenths of
a millimetre. Advantageously the skinning knife 4 is so
arranged that it can deviate awa~v from the periphery of the
skinning roller 2 against strong spring pressure. Arranged above
the cutting edge 41 o the slcinning knife ~ there may be an
intcgral or multi-part pre3ser roller 5, which is drivcn in thc
direction shown by the arrow on the periphery of the presser
roller and which is arranged to be deviatable against a spring
force. ~lowever~ instead of this pressure roller 5 there may be
provided a g~ide face 7 pivotable about an axis 71 parallel to
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the axis of the skinning roller 2.
- The cylindrical peripheral surface 2J o the skinning
roller 2 is divided b~ axial grooves 25 into lands 22 which
possess roughenings of small radial depth. The rough surface
may be provided by for example crossed knurls 23 OL fine
- toothing 24 which serve to entrain the skin along the presser
face 42 o~ the skinning knife 4, The grooves 25 have the shape
of non-unlfo~m trapeziums, the depth 27 of which amounts to
~- only a fraction of their width 26, and the trailing flanks of
which may be inclined oppositel~ to the direction of the
skinning roller 2. Each o the lands 22, when measured in the
direction of the circumference of the skinning roller 2, has a
width which is a multiple of the width o each of the recess
means. The width o the grooves may be about 5 millimetres
and their depth about 1.5 millimetres. The surface oE the
transfer roller 3 is provided with a fine toothing and also
- the surface of the presser roller 5 is advantageously provided
` with a profiling ~not shown) of small depth.
The apparatus operates as follows:
A fish fillet laid with its skin side on the feed belt 1
' is fed b~ the feed belt 1 with its tail end forward to the!
deflecting location above the deflecting roller 11, where
the transfer roller 3 guides the tail tip onto the peripheral
surface 21 of the skinning roller 2. The Eine toothing 31 of
the transer roller 3 is thus in a position to raise the
fillet end from the feed belt 1 but prevents excitation of the
~- fish Eillet end into a vertical flapping motion. The skinniny
roller 2 rotates more rapidly than the fed tail end of the
fish fillet and rotates with its lands 22 and grooves 25 below
the skin side of the fish fillet until the leading end
thereof has reached the cutting edge 41 o the skinning knife
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4. The merel~ low roughness oi the lands 22 of the skinning
roller 2 causes the skin ta rest 1ush on the peripheral sur-
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face 21. In consequence thereof, the skin o the tail end
drops briefly into the grooves 25 respectively passing through
below it, When the tail end of the fish fillet again pene-
trates with its skin into a groove 2S on reaching the cutting
edge 41 of the skinning knife 4 wedging of the skin takes place
instantaneously through the presser ace 42 lying below the
cutting edge 41 and enables the cutting edge 41 to penetrate
~ 10 between the skin and silver layer of the fish fillet and thereby
- to sever the fish ~illet from the skin. This process is per-
formed with great certainty when the fish fillet is conveyed
forward spread out from the feed belt 1. The presser roller 5
disposed above the cutting edge 41 comes into effect particularly
when irregularities are present in the position of the fish
, fillet.
The arrangement o a guide face 7 instead of the pressure
roller 5 is advantageous when very stiff and rigid fillets
are to be skinned. The skinning process may then be further
improved by providing for an oscillation of the guide face in
the conveying or feeding direction.
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