Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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System and method for processing shrimp
Field of the invention
The present invention relates to a system for processing shrimp or similar
crustaceans such as small crawfish and lobsters, said system comprising a
support for
supporting a batch of shrimp to be processed; a queuing mechanism having an
output and
adapted for transporting shrimps from the support to the output such that a
queue of shrimps
is formed in a queuing direction and only one shrimp of said queue is present
at the output
at a time; one or more processing stations for individually processing shrimp
or part thereof;
and a transport unit adapted for individually transporting shrimp between the
processing
stations. The processing stations preferably are adapted for individually
peeling a shrimp
or part thereof. The present invention further relates to a method for picking
up individual
shrimp from a batch of shrimp.
Background art
A machine for processing shrimp has been described in great detail in European
patent EP 0 152 462 Bl, in which one by one the shrimps are isolated exactly
on time in
the machine, and guided along four or six tracks per peeling machine, or a
multiple thereof,
so that the machine performs 60 operating strokes per minute, so that on the
basis of an
average of 720 shrimps per kg, an average of4 to 5 kg ofunpeeled shrimps can
be processed
per peeling unit per hour. Per track the machine is provided with a rotatable
peeling disc
adapted for clamping eight shrimp at a time, wherein during standstill of the
peeling disc a
tail pulling mechanism and meat removing mechanism respectively pulls a tail
from a
shrimp and rolls out the shrimp meat from a shrimp. In order to provide
individual shrimp
to the peeling disc, a number of spaced suction elements for picking up shrimp
is provided,
which suction elements undergo an angular displacement of about 30 degrees in
the course
of a reciprocating motion into and out of a vibratory receptacle in which a
plurality of
shrimps are kept moving to facilitate pick up of the shrimp.
However, the suction elements occasionally fail to engage a shrimp in the
vibratory
receptacle or engage more than one shrimp at a time, which slows down the
peeling rate
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and often results in incorrect peeling of the shrimps and corresponding damage
to the meat
of the shrimp and/or failure to remove all parts of the shell of the shrimp
during peeling.
US 3,576,047 describes an apparatus for peeling cooked shrimp, including a
cooker
belt conveyor having shrimp spread crosswise thereof, and distributor chutes
dividing
shrimp from said conveyor into a plurality of separate parallel streams, with
an air chute
and air blower for each stream so that shrimp are oriented to travel with
their heads trailing
down the air chute. A shaker table maintains such orientation during travel
and is arranged
to space the shrimp so they travel in sequence one after the other to a shrimp-
deshelling
means comprising shrimp-deshelling discs to receive therebetween shrimp. The
speed of
rotation of the peripheral portions of these discs is faster than the rate of
travel of the
shrimps along the chute, so that the discs contact shrimp one at a time
allowing a disc to
seize and pull the shrimp before the next shrimp in the chute reaches the end
of the chute.
However, due to the high speed o f the discs, the meat of the shrimps is
likely to be damaged,
whereas at the same time the peeling rate is severely limited as only one
shrimp is in contact
with the disc at any time.
Though the known peeling machines were a great improvement over manually
peeling shrimp, there is still a need in the industry for system and method
for processing
shrimp which allow faster processing of shrimp without damaging or otherwise
reducing
the quality of the meat of the shrimps.
NL 9 102 028 describes a dispensing device for regularly dispensing products,
such
as fish, from a quantity of such products comprises a container in which the
quantity of
products can be accommodated, as well as an conveyor wheel which can be moved
at least
partially through the container and is provided with suction cups for carrying
the products,
pressed against the conveyor wheel surface by means of vacuum, towards a
dispensing
point. The container is arranged downstream from a shaker table and adapted
for containing
several products at a time. In order to avoid products not being picked up by
the conveyor
wheel when only a few products are left in the container, a pressurized air
duct is provided
by means of which the products can be blown against the suction cups.
It is an object of the present invention to provide a method and system for
processing
shrimp capable of providing a higher shrimp processing rate, e.g. which allow
processing
of 10 or 15 kg or more of unpeeled shrimp per clamping wheel or peeling disc,
per hour,
without substantially reducing the quality of the shrimp meat.
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The invention further aims to provide a method and system for processing
shrimp,
wherein the number of shrimp that is processed per hour can be predicted to
highly accurate
degree.
Summary of the invention
To this end, according to a first aspect, the present invention provides a
system for
processing shrimp, comprising: a support for supporting a batch of shrimp to
be processed;
a queuing mechanism having an output and adapted for transporting shrimps from
the
support to the output such that a queue of shrimps is formed in a queuing
direction and only
one shrimp of said queue is present at the output at a time; one or more
processing stations
for individually processing shrimp or part thereof; and a transport unit
adapted for
individually transporting shrimp between the processing stations; wherein said
system
comprises a pick-up unit comprising a pick-up wheel comprising a number of
suction
nozzles arranged around the circumference of the pick-up wheel for picking up
individual
shrimp from the output, wherein the pick-up wheel is arranged for rotating
around an axis
of rotation relative to said output in a predetermined direction of rotation
such that during
a complete revolution of the pick-up wheel the suction nozzles sequentially
pass the output
for picking up a respective shrimp, and wherein said pick-up wheel is adapted
for, after an
individual shrimp held thereby has rotated about said axis, releasing said
shrimp in order
to supply the shrimp towards said transport unit. Though herein shrimp are
referred as the
crustaceans to be peeled, it will be clear that the system and components
thereof are also
suitable for peeling similarly sized and shaped crustaceans, such as crawfish
and lobsters.
The pick-up wheel generally comprises at least six suction nozzles arranged
equidistantly around the circumference thereon. After each complete revolution
of the
wheel the same suction nozzle is arranged at or near the output for picking up
a shrimp,
allowing a particularly reliable and fast way to pick-up an individual shrimp
by applying
of a vacuum force at that suction nozzle. As the shrimp are presented at the
output in a
single-file queue, only one shrimp can be picked-up by each nozzle at a time,
so that
damage to shrimp meat due to two or three shrimp being picked up together is
avoided. The
pick-up unit can achieve a high throughput, i.e. pick-up a high number of
shrimp per unit
time, as it rotates only in one direction so that no time is spent for moving
the pick-up wheel
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back and forth in a reciprocating motion. The pick-up unit may be provided
with several of
such pick-up wheels connected to each other in parallel and which rotate
around the same
axis of rotation to further increase the throughput of the pick-up unit. The
moment in time
at which each shrimp is released from the pick-up unit can be accurately
controlled and
may be set in advance to occur periodically at predetermined points in time.
This in turn
enables the transport unit to receive individual shrimp at predetermined
points in time,
without having to briefly stop movement of the transport unit in order to wait
for a shrimp
to be supplied. The transport unit can thus be kept continuously moving, in
particular at a
constant speed, which allows an increase rate of shrimp processing by the
system.
Additionally, as the number of shrimp that is released from the pick-up unit
towards the
transport unit for processing depends on the speed of rotation of the pick-up
unit, the
number of shrimp to be processed per unit time unit be determined in advance
to a highly
accurate degree.
Though throughout this application processing shrimp generally refers to
peeling
shrimp, the system can instead also be used for individually picking up shrimp
from a batch
shrimp and subsequently placing the individual shrimp in a predetermined
location, e.g. for
placing shrimp on a tray for packaging.
In an embodiment the queuing mechanism comprises two support members
arranged at said output and adapted for supporting a shrimp thereon such that
the shrimp is
at least partially arranged between said support members, and wherein said
suction nozzles
are arranged for moving between said two support members during rotation of
the pickup
wheel. When a shrimp is in contact with the two support members, e.g. two
parallel rods,
and supported thereon the shrimp thus bridges a space between the support
members and
the suction nozzles of the wheel can rotate through said space for picking up
a shrimp from
the output.
In an embodiment the suction nozzles are arranged in such a manner on the
rotating
pick-up wheel that they approach and engage shrimp on the support members from
a lower
side of the support members during rotation of the pick-up wheel. During
rotation, a suction
nozzle near the output thus is moved from a position below the output to a
position above
the output, so that when a shrimp is being picked up from the output it is at
least during a
portion of the rotation in part supported by the nozzle or a surface thereof,
regardless of
whether a vacuum is applied on the shrimp by the suction nozzle.
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In an embodiment the support members extend in a common plane, and each
suction
nozzle has a suction opening arranged for, when the suction nozzle is said
plane, applying
a suction force to the shrimp in a direction substantially normal to said
plane. Generally
this will mean that the axis along which the suction opening sucks in air is
normal to the
5 common plane of the support members, and preferably parallel to a tangent
of the pick-up
wheel at the point where the nozzle is attached to the pick-up wheel.
Additionally or
alternatively, the circumferential edge of the opening, when the suction
nozzle is at the
plane of the support members, can be arranged to extent substantially in said
plane. When
a shrimp is arranged at the output on the support members, e.g. such that its
carapace
extends substantially parallel with the support members, then as the suction
nozzle
approaches the shrimp, any distance between the opening of the suction nozzle
and the
portion of the shrimp it is to contact will thus be minimized along the edge
of the opening,
reducing the chance of the shrimp falling off the suction nozzle.
In an embodiment the diameter of the opening of the suction nozzle that comes
into
contact with the shrimp is between 2 and 6 mm, preferably of between 3 and 5
mm. Such
relatively small opening diameters have been found very suitable for picking-
up shrimp by
its shell. Such diameters are especially suited from picking up shrimp having
a length from
carapace to tail end of between 4 and 15 mm.
In an embodiment, the distance of the opening of the suction nozzle to the
first axis
of the pick-up wheel is fixed. As this distance remains constant during pick-
up and release
of a shrimp by the suction nozzle, the nozzle openings can be positioned very
precisely
relative to the output of the queuing mechanism. Moreover, the suction nozzles
of a simple
construction may be used, e.g. substantially without flexible and/or moving
parts.
In an embodiment the pick-up wheel comprises a stop surface arranged between
neighbouring suction nozzles and along the circumference of the pick-up wheel,
wherein
said stop surface is arranged for substantially blocking movement of a shrimp
from the
output towards the pick-up wheel when said stop surface is located at the
output. Thus,
when none of the suction nozzles is located at the output, propagation of a
shrimp at the
output to the pick-up wheel is prevented, thus also automatically
synchronizing pick-up of
shrimp from the output with the rotation of the pick-up wheel.
The stop surface and said suction nozzles are preferably arranged such that,
when a
part of a shrimp contacts the stop surface while a suction nozzle is located
at the output, the
suction nozzle is arranged for contacting the shrimp at a predetermined
distance from said
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part. Thus, if the stop surface contacts the head or tail part of a shrimp
that is present at the
output, the nozzle can engage the shrimp at a predetermined distance said
part, e.g.
approximately at a middle section of the shrimp which is more easily picked-up
with a
suction nozzle than the distal parts of the shrimp along the support which
generally
comprise tail segments or antennae of feelers of the shrimp. Preferably, a
distance between
the stop surface and the opening of the suction nozzle is bridged by a surface
of the suction
nozzle which extends substantially parallel to the support members and/or to
the nozzle
opening when the nozzle rotates through the space between the support members.
The
surface of the nozzle can thus at least partially bear the weight of a shrimp
when the nozzle
rotates through the space between the support members.
In an embodiment the suction nozzles are detachably attached to said pick-up
unit.
By exchanging the suction nozzles for differently dimensioned nozzles the pick-
up unit can
easily be adapted for picking-up differently size shrimp. Different sets of
suction nozzles
may be provided for the pick-up wheel, with the nozzles of each set adapted
for picking up
.. a specific type of shrimp based on expected average properties of shrimp in
the batch of
shrimp, such as average length of the shrimps in the batch, and/or average
weight of the
shrimp. Depending on the expected average length, the suction nozzles that are
attached to
the pick-up wheel may be selected such that when attached thereto the nozzles
all have their
opening at a distance from the stop surface suitable for picking up shrimp at
a middle
section of the shrimp. Likewise, depending on the expected average weight of
the shrimp
that is to be picked-up, nozzles having larger or smaller nozzle diameters may
be used, e.g.
nozzles with smaller diameter openings may be used for picking up heavier
shrimp, while
nozzles with larger diameter openings may be used for picking up lighter
shrimp.
Preferably, the nozzles that are attached to the pick-up wheel are selected
such that on
average, when a shrimp is at the output and in contact with both the stop
surface and a
suction nozzle, a distance between the stop surface and the opening of the
suction nozzle is
about half the length of the shrimp along the direction of the support
members.
In an embodiment the support comprises a transport mechanism for transporting
said shrimp from the support to the output. The transport mechanism preferably
is
embodied as a vibrating motor, e.g. adapted for moving the support
horizontally in a
reciprocating motion, wherein the horizontal movement of the support in a
direction
towards the pick-up unit is slower than the horizontal movement of the support
away from
the pick-up unit. Other suitable transport mechanisms include conveyors such
as belt
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conveyors and push conveyors. In some cases it may be advantageous to arrange
the
support at an angle to the horizontal and with the output sloping towards the
horizontal, to
facilitating transport of shrimp from the support towards the output.
Preferably, the support
is provided with adjustable diverter plates for dividing the batch of shrimp
into smaller
streams of shrimp, wherein an angle of the plates relative to the queuing
direction, when
seen in projection on the support, is adjustable. The support may further be
provided with
bumps elements or the like on the supporting surface of the support, for
causing shrimp that
are in contact with each other to be separated along the queuing direction.
In an embodiment, the system, preferably the pickup-unit thereof, further
comprises
a drive unit for driving the rotation of said pick-up wheel around said axis
and a controller
adapted for controlling said drive unit to substantially continuously drive
rotation of the
pick-up wheel around said axis during one or more complete revolutions of the
pick-up
wheel. The pick-up wheel thus rotates continuously in a single direction of
rotation during
supply of substantially the entire batch of shrimp to the transport unit, and
time consuming
reciprocating motions of the pick-up wheel for bringing the suction nozzles to
and from the
output are avoided. The controller is preferably adapted for controlling the
drive unit such
that during each complete revolution of the pick-up wheel the speed of
rotation is
substantially constant. Time and power required to bring the pick-up wheel
from a lower
speed of rotation to a higher speed of rotation is thus minimized or can be
avoided
altogether. The drive unit may be embodied as or comprise an electric motor,
e.g. a direct
drive motor which is directly connected to the drive wheel without an
intermediate
transmission. For instance, when the system comprises a frame which supports
the pick-up
wheel in such a manner that it can rotate around the axis of rotation, a
stator of the motor
may be fixed stationary relative to the frame and/or a part of the pick-up
unit that is
stationary relative to the frame, while a rotor of the motor may be fixed
stationary relative
to the pick-up wheel.
In an embodiment said transport unit comprises a frame and a clamping wheel
rotatable relative to said frame around a further axis of rotation and
comprising a plurality
of clamps, each adapted for clamping an individual shrimp, wherein said
clamping wheel
is adapted for continuously rotating in a further predetermined direction of
rotation for one
or more complete revolutions. Due to the highly predictable rate at which
shrimp are
released by the pick-up wheel of the pick-up unit, the clamping wheel can
receive individual
shrimp at predetermined points in time without having to briefly stop movement
of the
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wheel. For driving rotation of said wheel the system may be provided with a
drive unit,
which may be the same drive unit as the drive unit for driving of the pick-up
unit or a
separate drive unit, wherein the drive unit is controlled for driving
continuous rotation of
said clamping wheel around the further axis of rotation for one or more
complete
revolutions. Thus, transport of the shrimp along the processing stations and
processing of
the shrimp at said stations can be carried out during continuous smooth
rotation of the
clamping wheel. As with the pick-unit, the drive unit for the clamping wheel
is preferably
controlled such that during each revolution of the clamping wheel the
rotational speed is
substantially constant. Likewise, as with the pick-up unit, the transport unit
may comprise
several such clamping wheels which are connected to each other in parallel,
and which
rotate around the same further axis of rotation.
In an embodiment the or each clamping wheel comprises at least six clamps,
preferably at least eight, arranged at or near the circumference of said
clamping wheel, each
of said clamps comprising two moveable clamping surfaces each adapted for
clamping
against a corresponding lateral side of said shrimp without clamping against a
tail portion
of the shrimp. This allows peeling of a shrimp at the successive processing
stations by
separating the meat of the shrimp and/or portions of the shell thereof from
the portion of
the shrimp that is clamped. The clamps are preferably adapted for
substantially only
clamping a shrimp at its carapace.
In an embodiment the system further comprises a slide chute assembly having an
upstream distal end proximate to said pick-up unit and a downstream distal end
proximate
to said clamping wheel, wherein said slide chute assembly is adapted for
aligning individual
shrimp during sliding thereof from the upstream end to the downstream end such
that at
said downstream distal end the shrimp is supported by its dorsal side and
substantially
unsupported at its ventral side. The slide chute assembly ensures that the
shrimp are aligned
in a substantially predetermined manner for easy clamping when they reach the
clamping
wheel, and further ensures that the shrimp, when clamped on the clamping
wheel, are
oriented such that the processing stations, e.g. peeling stations, have access
to parts of the
shrimp to be processed. Preferably, the slide chute assembly is further
adapted for aligning
individual shrimp during said sliding such that the head part of each shrimp
is in a
predetermined orientation. For instance the slide chute assembly may orient
each shrimp
such that, when clamped by a clamp of the clamping wheel, the shrimp rotated
head first in
the direction of rotation of the clamping wheel.
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In an embodiment the slide chute assembly comprises a reciprocating chute at
the
downstream end, which reciprocating chute comprises said downstream distal
edge and is
adapted for extending towards the clamping wheel when no clamp is present
between the
clamping wheel and the edge in the direction of extension, and for
subsequently retracting
when a clamp approaches said edge to within a short distance. The short
distance preferably
is 1 cm or less, and more preferably 0,3 cm or less. The shrimp can thus more
smoothly
move from the distal end of the chute into the clamp, so that the risk of the
orientation of
the shrimp changing unexpectedly during said movement is significantly
reduced. Just
before the clamp nears the distal edge to an extent that it would collide
therewith, i.e. when
the clamp approaches the edge to within the short distance, the distal edge is
moved out of
the collision trajectory. Though this can be achieved by mechanically coupling
the
reciprocating chute to the rotation of the clamping wheel, preferably the
extension and
retraction of the chute is driven by a drive means, such as a motor, that is
separate from the
drive means of the clamping wheel and controlled by a controller.
In a preferred embodiment for each clamp said clamping wheel is provided with
a
corresponding moveable guide for guiding sliding movement of a shrimp from the
slide
chute assembly into said clamp, wherein said moveable guide is adapted for
moving, during
rotating movement of the clamping wheel in which the clamp is moved towards
said distal
end, from a position in which it extends substantially coaxial with said
clamp, to a position
in which it extends noncoaxially to said clamp and is arranged at least
partially below and
beyond said distal end. The clamps of the clamping wheel remain at a distance
spaced from
the distal end so as not to hinder rotation of the clamping wheel. During
rotation of the
clamping wheel each moveable guide bridges a substantial portion of this
distance when its
corresponding clamp approaches the distal end to receive a shrimp. The shrimp
can thus
move smoothly from the distal end into the clamp, so that the risk of the
orientation of the
shrimp during said movement changes unexpectedly is significantly reduced.
Just before
the guide nears the distal edge to an extent that it would collide therewith,
it is moved out
of the collision trajectory. To this end, each moveable guide is preferably
pivotably
connected to the wheel at a location near a leading edge of its corresponding
clamp.
Pivoting of each moveable guide at the correct relative position to the distal
edge of the
slide chute assembly can then be ensured in a variety of manners. Preferably
the pivoting
of the moveable guide is achieved by attaching each moveable guide to a
corresponding
follower shaft which extends partially into a circumferential curve track,
which curve track
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does not rotate together with the clamping wheel and is shaped and arranged
such that it
causes each follower shaft to urge its corresponding moveable guide to move
between the
coaxial and noncoaxial positions during a complete revolution of the clamping
wheel.
It will be clear that preferably a slide chute assembly is provided for each
pick-up wheel of
5 the
pick-up unit, and that the number of clamping wheels o f the transport unit
will in general
be equal to the number of pick-up wheels of the pick-up unit.
In an embodiment said slide chute assembly further comprises one or more
timing
wheels arranged in a path of said shrimp from said upstream end to said
downstream end,
for synchronizing delivery of shrimp to the distal edge. Each of the timing
wheels may for
10 this
purpose be provided with open and closed sections along its circumference,
such that
during rotation of the timing wheel a shrimp can only pass through if located
in one of the
open sections. The open sections may be embodied as cut out sections in the
timing wheel
which have at least the size of a shrimp. Though the moment a shrimp is
released from the
pickup-wheel can be determined highly accurately, the shrimps may vary
slightly in size
and weight causing them to slide at slightly different speeds along the chute
assembly. The
one or more timing wheels, which may be controlled to rotate at a speed
proportional to the
rotational speed of the clamping assembly, further improve the accuracy and
predictability
of the timing at which the shrimp reach an the distal edge, e.g. to be
accommodated in
clamp of the clamping wheel.
In an embodiment said one or more processing stations comprise one or more
peeling
stations adapted for peeling a shrimp or part thereof during continuous
rotation of said
clamping wheel in said further predetermined direction of rotation, said
peeling stations
comprising two or more of:
- a cutting station, for cutting the shell of a shrimp at a side of said
shrimp facing
away from the peeling wheel, preferably for cutting the third abdominal
segment at
the ventral side of said shrimp;
- a tail pulling station, for removing the tail of the shrimp;
- a ring removing station, for removing a ring segment of the shrimp;
- a meat removing station, for removing the meat of the shrimp.
As the smooth continuous movement of the clamping wheel does not have to be
stopped in
order for the peeling stations to peel a shrimp or portion thereof, a high
peeling rate can be
achieved.
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In an embodiment said tail pulling station comprises rotor rotatable around an
axis
of rotation in the same predetermined direction of rotation as said clamping
wheel, wherein
said rotor is provided with a gripper adapted to rotate relative to said rotor
in an opposite
direction of rotation to grip said tail portion of said shrimp between the
gripper and the a
surface of said rotor while the rotor and said clamping wheel rotate in the
same direction
of rotation. The rotor is preferably arranged for making one or more complete
revolutions
in the predetermined direction of rotation. The tail pulling station can thus
remove the tail
during continuous rotating motion of the clamping wheel without puncturing the
shrimp
with tines or the like, so that the meat of the shrimp remains substantially
undamaged.
In an embodiment said gripper comprises an elastic spring section for allowing
the gripper
to bend when gripping the tail portion of the shrimp, preferably wherein a
distal end of said
gripper comprises a roller for making rolling contact with the tail portion of
the shrimp.
The bending of the gripper and/or the rolling contact of the gripper with the
tail portion
ensure that the tail of each shrimp is gripped smoothly, even for differently
sized shrimp,
and without crushing the tail portion or damaging the meat of the shrimp.
Preferably the rotor comprises multiple such grippers pivotably arranged on
the
rotor with their pivot points spaced apart from each other along the direction
of rotation, so
that when one of the grippers grips the tail of a shrimp, another one of the
grippers can be
cleaned at a location spaced apart from the shrimp, e.g. using a water jet for
cleaning the
gripper and/or brushes for cleaning the gripper and optionally removing water
from the
gripper. It is thus substantially prevented that cleaning of an gripper has a
detrimental effect
on the meat of the shrimp.
In an embodiment said ring removing station comprises two pincer arms with
portions for clamping a shrimp therebetween, wherein said station is adapted
for moving
said arms in a reciprocating motion along with and against a direction of
movement of the
periphery of the clamping wheel proximate to the arms, wherein said station is
adapted for
bringing said portions towards each other for clamping the ring segment of the
shrimp
therebetween when the arms move along with the periphery of the clamping
wheel, and for
spacing said portions further apart from each other when the arms move against
the
direction of movement of the periphery of the clamping wheel. The ring segment
can thus
be pulled off the rest of the shrimp when the segment is clamped between the
pincer arms
while the clamping wheel continues to rotate. Preferably, the ring removing
station is
adapted for completely pulling the ring segment off the shrimp during movement
of the
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arms along with the movement of the clamping wheel, so that the pulling force
can be
smoothly applied to the segment.
In an embodiment said meat removing station comprises a rotor rotatable around
an
axis of rotation in a direction of rotation counter to the predetermined
direction of rotation
of said clamping unit, wherein said rotor is provided with a gripper for
gripping said meat
along lateral sides of the meat while said rotor and said clamping unit rotate
opposite
directions for removing the meat from the carapace. The gripper may comprise
two facing
surfaces for contacting the sides of the meat therebetween, wherein the
gripper is adapted
for smoothly moving the facing surfaces towards and subsequently away from
each other
during a complete rotation of said gripper. Preferably the gripper is adapted
for also rotating
the facing surfaces of the gripper in a direction counter to the direction of
rotation of the
rotor during said rotation of the rotor. The gripper of the meat removing
station smoothly
applies a gripping force to the meat of the shrimp, thus avoiding damaging the
meat as
would occur when tines or the like are used to pierce the meat, or when high
speed brushed
are used to force the meat out of its shell. The rotor is typically provided
with multiple such
grippers pivotably arranged on the rotor with their pivot points spaced apart
from each other
along the direction of rotation, so that when one of the grippers grips the
meat of a shrimp,
another one of the grippers can be cleaned at a location spaced apart from the
shrimp, e.g.
using a water jet for cleaning the gripper and/or brushes for cleaning the
gripper and
optionally removing water from the gripper.
In an embodiment, the shrimp processing system or the meat removing station
comprises a head stopper station provided with a retractable arm with a roller
at a distal end
thereof, wherein said head stopper station is arranged, in the direction of
rotation of the
clamping wheel, next to and after the position where the grippers of the meat
removing
station can engage a shrimp that is clamped on the clamping wheel, and wherein
said head
stopper station is adapted for moving said arm towards the clamping wheel such
that the
roller applies a pressure on the leading portion of a shrimp held by the clamp
while the
meat is being removed from the shrimp by the grippers of the meat removing
station, and
for retracting the arm away from the clamping wheel when the meat has been
substantially
removed so that the remaining portion o f the shrimp on the clamping wheel can
pass beyond
the head stopper station. The head stopper station thus allows the meat
removing station to
more effectively remove of meat from the shrimp.
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In an embodiment all parts of said peeling stations that come into contact
with the
shrimp meat are completely brushless, preferably wherein no part of the shrimp
meat is
contacted by a brush during processing. In principle, only the clamps and/or
the meat
removing station should come into direct contact with the meat of the shrimp.
The other
stations should only come into contact with the shell ofthe shrimp. In any
case it is desirable
that at any time a shrimp is in the system, the meat is treated gently, i.e.
is not subjected to
speed impact and is not pierced.
In an embodiment all parts of said peeling stations that come into contact
with the
shrimp meat are substantially free from water, in particular free from
pressurized water,
during contact with the shrimp meat. Preferably no part of the shrimp meat is
contacted by
water during processing once the shell of the shrimp has been compromised.
Though water
or pressurized water may be used to facilitate sliding movement of a shrimp
while its shell
is still completely intact, during peeling water should be prevented from
being absorbed in
the meat of the shrimp as this will cause the meat to spoil sooner. When the
meat removing
station and the tail pulling station comprise multiple grippers as described
above, one
gripper of one of these stations can be used for peeling a shrimp, while at
the same time
another gripper of the same station can be cleaned at a location spaced apart
from the
shrimp, e.g. using a water jet for cleaning the gripper and/or brushes for
cleaning the gripper
and removing water from the gripper. In this manner, water can be used to
clean portions
of the processing stations which at that time are not in contact with the
shrimp.
According to a second aspect, the present invention provides a method for
picking
up individual shrimp from a batch of shrimp, comprising the steps of: -
arranging shrimp
from the batch of shrimp in a single-file queue; - supporting shrimp at an
output of said
queue on two support members, such that the shrimp bridges a space between
said two
support members; and - activating a suction nozzle and moving it through said
space
between said two support members to pick up an individual shrimp at said
output. The
method is particularly suited for use with a pick-up unit and/or shrimp
processing system
as described herein. In a preferred embodiment the suction nozzle is arranged
on a pick-up
wheel which is arranged for rotating around an axis of rotation relative to
said output in a
predetermined direction of rotation such that during a complete revolution of
the pick-up
wheel the suction nozzle passes the output for picking up an individual
shrimp, wherein
said method comprises continuously driving rotation of said pick-up wheel
around the axis
of rotation at a substantially constant speed.
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Though preferably, the suction nozzle is arranged on such a pick-up wheel, it
will
be appreciated that in an alternative embodiment the suction nozzle instead
may be carried
on a circumferential conveyor which is not circular in shape, wherein the
conveyor and any
suction nozzles carried thereby are arranged for moving each of the suction
nozzles through
the space between the two support members to pick up an individual shrimp at
the output.
In an embodiment, said moving the suction nozzle through the space between the
two
supports comprises moving the suction nozzle in such a manner that it approach
and
engages shrimp on the support members from a lower side of the support
members.
The present invention will be discussed in more detail below, with reference
to the attached
drawings, in which:
Fig. 1 schematically shows a cross-sectional side view of system for peeling
shrimp
according to the invention comprising a receptacle, a pick-up unit, a slide
chute, a plurality
of peeling stations and a transport unit;
Fig. 2 shows a top view of the receptacle through line II-II of fig. 1;
Figs. 3A and 3B respectively show schematically a cross-sectional side view
and an
isometric view of the pick-up unit of fig. 1;
Fig. 3C shows a detail of section IIIC of Fig. 3A;
Fig. 4A-4C respectively show a side view, a perspective view, and partially
transparent front view of a transport unit 10 according to the invention;
Fig. 4D shows a front view of a curve track plate of figure 4B;
Fig. 5 schematically shows a side view of processing stations and a transport
unit
of a system according to the invention;
Figs. 6A-6C illustrate how the tail of a shrimp is removed using a tail
pulling station
according to the invention;
Fig 6D shows a more detailed side view of a tail pulling station of figs 6A-
6C;
Figs. 7A and 7B respectively show a top view of a ring removing station
according
to the invention in an open position and in a closed position;
Fig. 8A-8C illustrate how the meat of a shrimp is removed using a meat
removing
station according to the invention;
Fig. 9A and 9B respectively show a rotor of a meat removing station of figs.
8A-8C
in more detail.
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Description of embodiments
The general working of the system for processing shrimp according to the
invention
is described with reference to fig. lA which schematically shows a cross-
sectional side
5 view thereof The system comprises a frame 50 which supporting its various
other
components such as receptacle 1, pick-up unit 2, slide chutes assembly 3, 5,
timing wheels
4,7, push wheel 8, stop mechanism 9, transport unit 10 and peeling stations
12, 13, 15, 16
and 17, as well as rotating brushes 14a-14c.
A batch of shrimp to be peeled, which preferably have their carapace still
attached,
10 enter the system at a position indicated by the arrow A in a
receptacle 1. The receptacle is
adapted for moving shrimp along a queuing direction Q in such a manner that at
the output
1.8 of the receptacle individual shrimp are transported in a single-file queue
towards a pick-
up unit 2. The pick-up unit 2 comprise a pick-up wheel 2.5 rotates
continuously, i.e. without
intermittingly standing still during processing, in a direction of rotation R1
relative to an
15 output 1.8 of the receptacle 1, and is provided with a number of
suction nozzles 2.3 arranged
along the circumference of cylinder 2.1. Each time a nozzle is positioned at
the output 1.8,
an individual shrimp is picked up from the output by sucking the shrimp onto
the nozzle.
When none of the nozzles is positioned at the output 1.8, shrimp cannot move
from the
output 1.8 onto the pick-up wheel 2.5. After the pick-up wheel has rotated
about 250
degrees, shrimp that were picked up are ejected from opening into first slide
chute 3 of slide
chute assembly 3,5, by ejecting a burst of pressurized air through the suction
nozzle holding
the shrimp. The continuous rotation of the pick-up wheel 2.5 in direction R1
continues at
least until no shrimp are present at the output, e.g. when substantially all
shrimp have been
picked up from the receptacle 1.
The slide chute 3 is arranged for orienting individual shrimp such that the
head of
each shrimp trails the tail of the shrimp along the direction of movement P1
of the shrimp
when the shrimp reaches the downstream end of the first chute 3. The slide
chute 3 also
helps to move the shrimp towards a dorsal orientation in which the shrimp lies
on its back
on slide chute 3. At the downstream end of the slide chute 3 the system is
provided with a
timing wheel 4 which is adapted for rotating in a direction of rotation R2
which is the same
as the direction of rotation Rl. At predetermined moments in time the timing
wheel 4 lets
a shrimp pass tail first from first chute 3 to a second chute 5. The second
chute 5 is adapted
for orienting the shrimp such that its dorsal side faces downwards, so that
when the shrimp
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reaches second timing wheel 7, it is oriented on its back and with its head
facing away from
the wheel 7. The second timing wheel 7, which is arranged above the second
chute 5 at a
distance stream upwards of the downstream end of the chute, rotates in a same
direction of
rotation R3 as the directions of rotation R1 and R2 and at predetermined
moments in time
lets a shrimp pass towards the downstream end of the chute 5. The second
timing wheel 7
thus compensates for possible differences in amount of time taken by different
shrimp,
which may have different shapes and weights, for sliding down the chute 5. It
is thus
ensured that shrimp leave the downstream distal end of the chute 5 at highly
predictable
moments in time.
When leaving the downstream end of the chute 5, the shrimp comes into contact
with a push wheel 8 which rotates around its central axis in a same direction
of rotation R4
as direction of rotation R1 to push the shrimp towards transport unit 10. The
transport unit
10 comprises a clamping wheel 10.1 which is provided with several clamps, each
for
clamping a single shrimp, and rotates in a same direction of rotation R5 as
the direction of
rotation Rl. The push wheel 8 is arranged between the downstream end of the
second slide
chute 5 and a stop mechanism 9. The stop mechanism 9, at least when in contact
with a
shrimp, rotates in a direction of rotation R6 that is counter to a direction
of rotation R5 in
which the transport unit 10 rotates around its centre axis and relative to the
frame 50. The
stop mechanism 9 stops the shrimp when it has left the downstream end of the
second chute
5 and prevents the shrimp from sliding out of the clamp of the transport unit
10 before the
clamp has properly clamped the shrimp.
Once the shrimp has been clamped on the transport unit 10, the shrimp is
transported
head first and dorsal side up by continuous rotation of the clamping wheel
10.1 in direction
R5, along processing stations in the form of peeling stations 12, 13, 15, 16
and 17 which
are arranged along about half of the circumference of the clamping wheel 10.1.
In order of
position along that circumference the peeling stations comprise a cutting
station 12 for
making an incision in a ventral shell part of the shrimp, a tail pulling
station 13, a ring
removing station 15, for removing an abdominal ring of the shell, and a meat
removing
station 16 for removing the shrimp meat, or peeled meat, from the remaining
portion of the
shrimp that is clamped on the transport unit 10. During processing of a shrimp
by the meat
removing station, and while the clamping wheel continues its rotation, a
rotatable wheel of
a head stopping station 17 is moved in the direction of the clamping wheel to
provide
pressure on the head of the shrimp while the meat is removed. Once the meat is
removed,
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the wheel of the head stopping station is moved away from the clamping wheel
so that the
remaining portion of the shrimp that is still clamped by the clamp can move
through more
easily and without pressure being exerted thereon by the head stopping
station.
The shrimp meat that is removed falls down direction P5 and is collected in
container 20. That portion of the shrimp that is still held by a clamp of the
transport unit 10
is released before the clamp reaches the position where another shrimp us
supplied from
the second chute 5 into the same clamp, and the process is repeated.
Throughout processing
of the shrimp in the system all parts of said processing stations that come
into contact with
the shrimp meat are completely brushless, so that damage to the meat is
avoided. During
brushing of parts of the processing stations, the brushes contact only those
portions of the
station which at that time are not in contact the meat of the shrimp and/or a
portion of the
shrimp that is further to be processed. Likewise, all parts of said processing
stations that
come into contact with the shrimp meat are substantially free from water,
though those parts
may be cleaned used water when not in contact with shrimp meat and/or a
portion of the
shrimp that is further to be processed.
A cross-sectional top view of the receptacle 1 through line II-II of fig. 1 is
show in
fig. 2. When a batch of shrimp is inserted in the receptacle 1, the shrimp are
supplied on
surface 1.1. Though not the case for the embodiment presently shown, the
surface 1.1 may
be at a slight angle to the horizontal so that the output 1.8 is at a lower
level than the surface
1.1. The receptacle 1 is attached to the frame 50 via elastically deformable
rubber blocks
1.9 which allow the receptacle to move slightly relative to the frame 50. A
vibrating motor
1.10 is provided at a rear end of the receptacle 1, and is adapted for shaking
the receptacle
back and forth along horizontal vibration direction V to urge movement of the
batch of
shrimp towards the output 1.8. During said movement, the batch is split up
into smaller
streams of shrimp by adjustable diverting plates 1.2 which are arranged for
diverting
portions ofthe streams away from each other. By adjusting the angle ofthe
individual plates
relative to the queuing direction Q, e.g. by rotating one or more of said
plates around an
axis which extends normal to surface 1.1, it can be ensured that each of the
streams contains
substantially the same amount of shrimp. Bump elements 1.3 and 1.4 are
arranged for
separating shrimp that lie at least partially on top of each other, until
finally separator plates
1.5 separate the shrimp into six separate queues at a-f, and the shrimp are
moved single file
on six pairs of support members, in this case rod pairs 1.6a ¨ 1.6f, towards
outputs 1.8a ¨
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1.8f. Shaking movement of the receptacle 1 also causes shaking movement of the
pairs of
rods connected thereto. The rods of each pair extend parallel to each other
and are spaced
in such a manner that a shrimp can be supported by both rods and partially
therebetween
during movement towards the corresponding output 1.8a-1.8f. This helps in
orienting each
shrimp along its longitudinal axes before it reaches the output. At the upper
sides of the
rods which face away from each other, the rods of each pair are connected to
corresponding
pairs of sidewalls 1.7a ¨ 1.7f which extend parallel to the rods and a spaced
apart a greater
distance from each other than the distance between the rods of a pair. The
sidewalls, which
do not extend as far towards the pick-up unit as the rods do, thus prevent the
shrimp from
falling across said upper side of the rods.
Figs. 3A and 3B schematically show respectively a side view a pick-up unit as
used
in the system of fig. 1 and an isometric view of a portion thereof. Fig. 3A
shows the pick-
up unit 2 provided with a pick-up wheel 2.5 formed by a cylinder 2.1 to which
eight suction
nozzles 2.3 are attached equidistantly along the circumference of the cylinder
2.1. As can
be seen in Fig. 3B, a number of parallel tracks with suction nozzles can be
arranged around
the circumference of the cylinder, e.g. in Fig. 3B three such tracks are
shown, each track
having 8 suction nozzles which are arranged for moving past respective outputs
1.8a ¨ 1.8c.
Each nozzle has a nozzle opening 2.6 which extends normal to a radial
direction of the
cylinder 2.1 such that when the nozzle rotates around its axis Al in the
direction R1, the
nozzle opening approaches a shrimp at the output substantially parallel to a
plane in which
the corresponding pair of rods extend. A stop surface 2.2 extends between
neighboring
suction nozzles, and bounds the extent to which a shrimp can move along the
queuing
direction towards the pickup unit 2.
The eight suction nozzles 2.3 are detachably attached to the cylinder 2.1 and
can be
replaced with eight different suction nozzles for applying a suction force to
different kinds
of shrimp, e.g. shrimp that have been sorted into different categories
depending on weight
and shape prior to being placed in the receptacle. For example, when a shrimp
is provided
at the output and is in contact with the stop surface 2.2, whether the suction
nozzle applies
a suction force to a middle portion or end portion of a shrimp depends on the
distance of
the nozzle opening 2.6 to the stop surface 2.2. By replacing the suction
nozzles which have
their suction opening at a first distance from the stop surface with nozzles
having their
suction opening at a second, different distance from the stop surface,
different kinds of
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shrimp can easily be picked-up using the pickup unit of the invention. Fig. 3C
shows a
detail of the opening in the suction nozzle 2.3 shown in section IIIC of fig.
3A.
Fig. 3B shows an isometric view of the pick-up unit of Fig. 3A. During
rotation of
the pick-up unit 2 in the direction of rotation R1, the nozzles 2.3 are moved
from a position
below rods pairs 1.6a ¨ 1.6c, between the rods of those pairs, to a position
above the rod
pairs 1.6a ¨ 1.6c. Each of the outputs 1.8a -1.8c at the distal ends of the
rod pairs is arranged
between radially extending flanges 2.4 of the pickup unit 2, which prevent
lateral
movement of the shrimp so it does not fall over the sides of the rods.
In the embodiment shown, three rod pairs 1.6a-1.6c are provided for
individually
supplying shrimps from streams a-c to outputs 1.8a-1.8c, wherein the shrimp
from each
output are picked up by three corresponding sets of nozzles, with the nozzles
in each set
being arranged equidistantly around the circumference of the pick-up unit.
During rotation
of the pick-up wheel 2.5 the nozzles of each set are thus periodically
positioned at their
corresponding output 1.8a-1.8c.
Referring back to Fig. 1, once a shrimp has been picked-up and the pick-up
wheel
has made at least half a revolution, the shrimp is released from the nozzle by
ejecting a blast
of pressurized air from the nozzle. This ensures that the shrimp is cleanly
separated from
the nozzle and helps to keep the nozzle opening substantially free from dirt
such as may be
formed by small pieces of shrimp.
Fig. 4A schematically shows a side view of a transport unit 10 according to
the
invention. The transport unit 10 of Fig. 4A comprises a clamping wheel 10.1
which is
rotatable relative to frame 50 around its center 10.2 in a direction of
rotation R5. A total of
eight clamps 10.11¨ 10.18 are arranged equidistantly along the circumference
of the
clamping wheel 10.1, though for reasons of clarity, the clamps are only
partially shown, i.e.
the lower surface of the clamps which are fixed to the clamping wheel 10.1 are
shown, but
the actual clamping surfaces that are moveable relative thereto have not been
shown. Each
clamp is adapted for clamping a single shrimp at the lateral sides of the
shrimp with the
clamping surfaces in such a manner that its tail portion is not clamped.
In the position of the clamping wheel shown in Fig.4A, a leading portion 10.31
of
the clamp 10.11 is spaced at a distance dl from the downstream distal end 5.1
of the second
chute 5 which is stationary relative to frame 50. In order to prevent a shrimp
from falling
into the space between the distal end 5.1 and the leading portion 10.31 before
being
clamped, the clamp 10.11 is provided with a corresponding moveable guide
10.51. Again,
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for reasons of clarity Fig. 4A only shows the moveable guides 10.51 and 10.52
for clamps
10.11 and 10.12 and the corresponding leading edges 10.31 and 10.32 of the
clamps,
however in practice each of the clamps 10.11 - 10.18 is provided with a
corresponding
moveable guide 10.51 - 10.58. Each moveable guide is adapted for guiding
sliding
5 movement of a shrimp from the distal end 5.1 of the slide chute 5 into
the corresponding
clamp while rotation of the clamping wheel moves the clamp towards said distal
end.
During this rotational movement, the moveable guide 10.51 is moved from a
position in
which it extends substantially coaxial with said clamp, as shown, to a
position in which it
extends noncoaxially with said and at an angle thereto, and is arranged at
least partially
10 below and beyond said distal end. Once the moveable guide has moved
under the distal end
5.1 it can remain in the non-coaxial position, as is shown for moveable guide
10.52, until
it is moved close towards the edge 5.1 again.
Fig. 4B shows an isometric view of the transport unit 10 with a single
clamping
wheel 10.1 which rotates around its center 10.2. Again for reasons of clarity,
only two of
15 the eight clamps and only three of the eight corresponding moveable
guides are shown in
figure 4B, though all clamps and corresponding moveable guides are of a
similar or same
construction. Clamp 10.11, which is just approaching distal edge 5.1 of slide
chute 5, is
shown with its movable clamping surfaces in a non-clamping position for
receiving a
shrimp. The corresponding moveable guide 10.51 of the clamp 10.11 is shown
oriented
20 coaxially with the clamp, so that a shrimp can slide from the distal
edge 5.1 over the
moveable guide 10.51 and into position in the clamp 10.11. As the clamp 10.11
is rotated
with the clamping wheel 10.1 in the direction R1, the clamp 10.11 is closed
and its
moveable guide is pivoted to a non-coaxial orientation with the clamp, so that
it can move
under the distal edge 5.1. Eventually the clamp 10.11 and its corresponding
moveable guide
10.51 will be in a same position and orientation as clamp 10.18. The clamp
10.18 is shown
with its moveable clamping surfaces 10.48 in a clamping position for clamping
lateral sides
of a shrimp and has its corresponding moveable guide 10.58 oriented non-
coaxially with
the clamp 10.18.
Movement of each moveable guide 10.51 - 10.68 relative to the fixed lower
surface
10.21-10.28 of its corresponding clamp is effected by means of follower
shafts, only two
of which, 10.152 and 10.151 are shown, which cooperate with the first curve
track 10.101
in a curve track plate 10.100 which is stationary relative to frame 50.
Rotation of the
clamping wheel 10.1 relative to the curve track plate 10.100 causes the
follower shafts
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10.151 and 10.152 that are moveably accommodated in the first curve track
10.101 to move
radially inward and outward at predetermined positions of rotation of the
clamping wheel
relative to the curve track plate 10.100. A trailing portion of each moveable
guide is
pivotably attached to the clamping wheel near a leading portion of its
corresponding clamp,
and a leading portion of each moveable guide is pivotably connected to
corresponding track
follower shaft 10.151, 10.152.
Opening and closing of each clamp 10.11-10.18 is effected by means of
corresponding follower shafts 10.111-10.118, only two of which, 10.111 and
10.118 are
shown, which cooperate with a second curve track 10.102 in the curve track
plate 10.100.
For each clamp, the clamping wheel is provided with a radially moveable knife,
adapted
for cutting a portion of a shrimp which faces the lower surface of the clamp.
Each fixed
lower clamp surface 10.21 -10.28 is provided with a slit 10.61-10.68 through
which the
corresponding knife can be moved radially outward to cut a portion of the
shell of a shrimp
in the clamp. For effecting said radial movement of the knifes in the clamping
wheel, each
knife is connected to a corresponding follower shaft which is partially
accommodated in a
third curve track 10.103 of the curve track plate 10.100. In Fig. 4B only the
follower shafts
10.177 and 10.178 for the knifes 10.77 and 10.78 of clamps 10.17 and 10.18 are
shown.
Two of the radially moveable knifes are shown in the partially see-through
side
view of fig. 4C. In this figure both knifes 10.76 and 10.77 are in a retracted
position, in
which they do not pass through the lower surface of the clamp via the slits in
said lower
surfaces. However, during movement of the corresponding follower shaft for
each knife
along a portion in the third curve track which corresponds the clamp being
moved along
the cutting station 12 of figure 1, the knife is moved radially outwards along
the
corresponding direction K of said knife, through the slit to cut the side of
the shrimp which
faces the lower surface of the clamp. When the clamp holding the shrimp has
passed the
cutting station, the knife is moved radially inward again so that its edge no
longer projects
out of the corresponding slit.
Fig. 4D shows a side view of the curve plate 10.100 in which the first curve
track
10.101 for follower shafts of the moveable guides, the second curve track
10.102 for the
follower shafts of the clamps, and third curve track 10.103 for the follower
shafts of the
radially moveable knifes can be more clearly seen. Each moveable guide is
pushed to an
orientation in which it is coaxial with its corresponding clamp, or lower
surface thereof,
when the follower shaft for the moveable guide is at segment 10.104 of the
first curve track
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10.101, and otherwise is pushed to an orientation in which it is noncoaxial
with the clamp.
The moveable clamping surfaces of each clamp are moved to an open position for
receiving
or releasing shrimp, when the follower shaft for the clamp guide is at segment
10.105 of
the second curve track 10.102, and otherwise are in a clamping position for
clamping a
shrimp therebetween. In a similar fashion, each knife corresponding to a clamp
is moved
radially outward to cut a shrimp when its follower shaft is at segment 10.106
of the first
third track 10.103, and is otherwise retracted inwards.
The position and orientation of the moveable guide relative to its
corresponding
clamp of the clamping wheel, whether that clamp is in an open or closed
position, and
whether a knife corresponding to a clamp projects through the slit in the
lower surface of
the clamp or not, are thus all determined by the position of rotation of the
clamping wheel
10.1 relative to the plate 10.100.
A side view of both curve tracks is shown in fig. 4D. When a track follower
shaft
in the first track 10.31 which is coupled to a corresponding moveable guide is
moved
radially outward at section 10.31, the moveable guide is coaxially aligned
with its
corresponding clamp. When the track follower shaft travels through the
remaining portion
of the first track 10.31, the moveable guide is aligned non-coaxially with its
clamp.
Likewise, when a track follower shaft in the second track 10.32 which is
coupled to a
corresponding clamp is moved radially outward at section 10.33, the clamp is
opened.
When the track follower shaft travels through the remaining portion of the
second track
10.32, the clamp remains closed.
Fig. 5 schematically shows a side view of embodiments of peeling stations
12,13,15,16, and 17 and a transport unit 10 of a system according to the
invention. The
transport unit 10 comprises a clamping wheel 10.1 and is adapted for
continuously rotating
the clamping wheel at a substantially constant speed of rotation is around its
axis of rotation
in direction of rotation R5. A shrimp that is supplied to the clamping wheel
from
downstream end 5.1 of slide chute 5, is pushed onto one of the eight clamps of
the clamping
wheel by push mechanism 8 which rotates in direction R4 which is the same as
direction
R5. Stop mechanism 9, which rotates counter to direction R5 at least when
contacting a
shrimp, prevents the shrimp from falling out of the clamp.
Once the shrimp has been clamped on the clamping wheel 10.1, it is transported
head-first along cutting station 12 and tail pulling station 13, which are
described in more
detail with reference to figures 6A-6D. After the tail has been removed at
station 12, the
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shrimp is moved on to ring removal station 15 which is described in more
detail with
reference to figures 7A and 7B, and where an abdominal ring segment of the
shrimp is
removed from the clamping wheel.
.. Subsequently, the remaining portion of the shrimp is transported to meat
removal station
16 which is described in more detail with reference to figs 8A-8C and 9A and
9B. The
clamping wheel continuously rotates at a constant speed while the shrimp
passes along the
stations. Those portions of the tail pulling station 13 and the meat removing
station 16
which come into contact with the shrimp are adapted for doing so in an
uninterrupted
smooth rotating motion, with said contacting portions making complete
revolutions during
processing of consecutive shrimp. The smoothness of the motion reduces and
avoids
damage to the shrimp meat, and as the contacting portions make complete
revolutions
processing can be carried out in a faster and more continuous manner.
Brushes 14a-14c are provided for respectively cleaning those portions of tail
pulling
station 13, meat removing station 16 and the clamps of the clamping wheel 10.1
which have
come into contact with the shrimp but which are not in contact with a shrimp
during
cleaning thereof by the brushes. Contact of brushes with meat of the shrimp is
thus
completely avoided in the system according to the invention.
Figs. 6A-6C schematically illustrate how initial cuts are made in the shell of
the
shrimp and how subsequently the tail is pulled off, and fig. 6D shows a detail
of a tail
pulling station according to the present invention.
Fig. 6A starts when a curled shrimp S has been clamped on a clamp of the
clamping
wheel 10.1 just after the shrimp has been supplied to the wheel, e.g. from the
downstream
edge of chute 5 of figure 1. Curling of the shrimp may have occurred during
boiling of the
shrimp e.g. prior to being placed in the receptacle. During transport of the
shrimp S along
the direction of rotation R5, and at least partially while a cut is made in
the ventral side of
the shrimp by rotating knife 12.1, the tail T of the shrimp is held back by
tail stretcher 11.
The tail stretcher 11 contacts the tail at location that is spaced apart
further from the center
of the clamping wheel 10.1 than the contacting edge of rotating knife 12.1, so
that in
principle that portion of the shrimp that is clamped, i.e. the lateral sides
of the shrimp, can
be moved under the tail stretcher 11 without making contact therewith.
As described above and shown in Fig. 4C, for each clamp on the clamping wheel
10.1 the wheel is provided with a corresponding moveable knife for cutting the
dorsal side
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24
of the shrimp. Each knife is moved radially outward from and back towards the
centre of
the wheel 10.1 by means of its corresponding follower shaft which is connected
at one end
to the knife and extends moveably in a radial direction of the wheel. When the
follower
shaft reaches segment 10.106 of the third curve track 10.103, the knife is
moved to make
an incision in the dorsal side of the shrimp S while its tail is held back by
the tail stretching
mechanism 11.
With the shell section of the shrimp which connects the tail shell part to the
rest of
the shrimp weakened by the incisions, the shrimp is subsequently transported
to tail pulling
station 13 which is provided with a rotor 13.1 which rotates in a direction R7
that is the
same as direction or rotation R5 of the clamping wheel.
The rotor 13.1 has three rotor surfaces 13.3, 13.4 and 13.5 that are
rotationally fixed
with respect to rotor, and further comprises three respective elastic
grippers, only one of
which, gripper 13.13, is shown in figs. 6A-6B. The tail pulling station is
described in more
detail with reference to figure 6D, in which the two other grippers are also
shown.
Fig. 6A shows that the tail of a shrimp, once the shrimp has passed the
cutting station
12, can spring at least partially back to an unstretched state before reaching
tail pulling
station 13. Fig 6B shows that rotor surface 13.3 at least partially stretches
the tail T of the
shrimp again when the rotor 13.1 and the clamping wheel 10.1 both rotate
continuously in
same directions of rotation R5 and R7. During said stretching, the gripper
13.13 rotates in
a direction counter to R7, so that the tail of the shrimp is gripped between
the roller 13.23
at the end of the gripper 13.13 and the rotor surface 13.3, as shown in Fig.
6B. Continued
rotation of both the rotor 13 and the clamping wheel 10.1 causes the tail to
be pulled off the
shrimp, as shown in Fig. 6C. When the rotor then continues its rotation, the
gripper 13.13
releases the tail portion of the shrimp so that it can be disposed of before
the rotor surface
is cleaned by brush 14A.
Figure 6D shows a detail of the tail pulling station, in which all grippers
13.13 ¨
13.15 are shown. The tail pulling station comprises a ring 13.2 that is
arranged stationary
to the frame 50, and which comprises a toothed portion 13.3 at the
circumference of the
ring 13.2 near the clamping wheel 10.1. The toothed portion only extends along
the
circumference of the ring over an angle during which the gripper should grip,
or should be
moved to grip, the tail of a shrimp, for instance over one twentieth of the
circumference of
the ring. When the toothed portion is engaged by gears 13.43, 13.44 and 13.45
which are
attached to the respective grippers 13.13, 13.14 and 13.1 and rotatable
relative to the rotor
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13.1, the gears cause the grippers to rotate in a direction R8 relative to the
rotor 13.1, which
is opposite to the rotational direction R7 of the rotor 13.1. This results in
the tail of the
shrimp being gripped between the respective roller 13.23, 13.24, 13.25 and
corresponding
rotor surface 13.3, 13.4, 13.5 while the portion of the shrimp that is clamped
on the wheel
5 continues to be moved in direction R5, and the tail T is pulled away
therefrom in direction
R7.
Fig. 7A shows a top view of a ring removing station 15 according to the
present
invention. The ring removing station is provided with two pincer arms 15.2,
15.3 with
portions 15.4, 15.5 for clamping a ring of a shrimp therebetween. Also
referring back to
10 figure 5, it can be seen that a cam wheel 15.15 continuously rotates to
periodically push
against follower wheel 15.15 along a direction P3 towards clamping wheel 10.1
while the
clamping wheel is rotated along the ring removing station 15. This causes a
reciprocating
motion of the shafts 15.6, 15.7. Rollers 15.8 and 15.9 at the ends of shafts
15.6, 15.8 cause
the portions 15.4 and 15.5 of the respective arms 15.2, 15.3 to move away from
each other
15 as shown in fig. 7A, so that a ring of a shrimp that is to be removed
can be moved
therebetween.
When the cam of cam wheel 15.1 no longer pushes against the follower wheel
15.15,
both shafts 15.6, 15.7 are moved away from the clamping wheel 10.1 along
direction P3,
by a spring force exerted by springs 15.8, 15.9 which extend along the shafts
and are fixed
20 at one end to plate 15.16 that is stationary to the frame 50 of the
processing system. During
rotation of the cam wheel 15.15 the portions 15.4, 15.5 are moved in a
reciprocating motion
towards each other for clamping the ring segment of the shrimp therebetween
during
rotation along said station of a clamp of the clamping wheel 10.1 holding said
shrimp, as
shown in Fig. 7B, and away from each other for releasing the clamped ring
segment when
25 said clamp has rotated away from the ring removing station, as shown in
Fig. 7A.
When the tail and ring have been removed, the carapace of shrimp is held
clamped
by a clamp on the clamping wheel, and a meat portion of the shrimp is exposed.
Figures 8A-8C schematically illustrate how the meat is removed from a shrimp
at a
meat removing station 16 during continuous rotation of both the clamping wheel
10.1 and
of a rotor 16.1 of the meat removing station in a direction of rotation R9
counter to the
direction of rotation R5 of the clamping wheel. The rotor 1.6 is provided with
a gripper,
shown in Figs. 9A and 9B, for gripping the shrimp meat at the lateral sides
thereof When
rotor 16.1 rotates the gripper to a position proximate to the clamp holding
the shrimp, the
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gripper engages said lateral sides. At the same time a roller 17.1 of head
stopper station 17
is moved towards the clamping wheel to a position in which it pushes against
the leading
portion of the shrimp while the shrimp meat is being gripped, as shown in Fig.
8A. The
pressure applied by the roller 17.1 prevents the carapace from being partially
pulled out of
the clamp by the gripper and also helps to squeeze the meat ofthe shrimp out
ofthe carapace
in a direction counter to direction of rotation R5. The head stopper station
may be embodied
as part of the meat removing station.
Further rotation of the rotor and of the clamping wheel 10.1 subsequently
cause the
shrimp meat to be pulled away from the clamping wheel, while carapace C of the
shrimp
remains clamped on the clamping wheel 10.1, as shown in Fig. 8B. Finally, as
the rotor
16.1 continues its rotation, the gripper opens, as shown in Fig. 8B, up to let
the meat fall
out of the gripper, e.g. along direction P5 into a container 20 for shrimp
meat as shown in
Fig. 5. After releasing the meat the portion of the rotor 16.1 where the
gripper is located, is
brushed by brush 14C.
Though Figs. 8A - 8C show a rotor with only a single gripper, it will be clear
that
preferably multiple grippers are provided on the rotor, so that one gripper
may be used for
gripping a shrimp, while another gripper is cleaned while it is not in contact
with shrimp
meat, e.g. by brushing or using a water jet. In particular, the rotor shown in
Figs. 8A - 8C
may comprise three such grippers, spaced equidistantly around the
circumference of the
rotor, as shown in fig. 5.
Figs. 9A and 9B respectively show an isometric view and a top view of a rotor
16.1,
here shown with a only single gripper 16.20 for reasons of clarity, though in
practice the
rotor will has three such grippers along the circumference. The gripper 16.20
is rotatably
arranged on a shaft 16.23 which extends parallel to the axis of rotation A2 of
the rotor 16.1
and is spaced apart therefrom. The gripper shaft is provided with a gear wheel
16.24 which
engages a main gear wheel 16.2 that is fixed to a central shaft 16.3 which
coincides with
axis of rotation A2. The main gear wheel 16.2 of the meat removing station is
stationary
relative to frame 50, so that when the rotor 16.1 is rotated around its axis
A2 in direction
R9, the stationary main gear wheel 16.2 the rotating gear wheel 16.24 at the
end of the
gripper shaft 16.23 cause the moveable surfaces 16.21, 16.22 of the gripper
16.20 to rotate
in an opposite direction of rotation R10.
Rollers 16.30 and 16.31 are arranged on respective axles 16.32, 16.33 which
extend
through the central shaft 16.3 and perpendicular thereto. When the outer sides
of gripper
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surfaces 16.21 and 16.22 contact the rollers 16.30, 16.31, the moon-shaped
moveable
surfaces 16.21, 16.22 are moved towards each other along direction P6 to
engage the lateral
sides of a shrimp.
Fig. 9B further shows a spring 16.25 arranged for biasing the gripper surfaces
to a position
further away from each along the axis of rotation A3 of the gripper. As the
central shaft
16.3 is stationary relative to the frame, the position at which, and extent to
which, the
moveable surfaces are moved towards each other and away from each other, is
determined
by the position of the rollers 16.30, 16.31 on the central shaft 16.3. The
rollers 16.30, 16.31
and/or axles 16.33,16.33 are therefore preferably attached to the central
shaft 16.3 in an
adjustable manner such that the position of one or both of the rollers along
the axis of
rotation A2 can be adjusted.
In summary, the present invention relates to a system for processing shrimp or
similar crustaceans such as small crawfish and lobsters, said system
comprising a support
.. for supporting a batch of shrimp to be processed; a queuing mechanism
having an output
and adapted for transporting shrimps from the support to the output such that
a queue of
shrimps is formed in a queuing direction and only one shrimp of said queue is
present at
the output at a time; characterized by a pick-up unit with a pick-up wheel
comprising
suction nozzles for picking up individual shrimp from the output during
continuous rotation
of the pick-up wheel relative to said output. The invention has been described
above with
reference to a number of exemplary embodiments as shown in the drawings.
Modifications
and alternative implementations of some parts or elements are possible, and
are included in
the scope of protection as defined in the appended claims. In particular, the
transport unit
and/or the individual processing stations described herein may be used
separately from the
rest of the system, and may be the subject of one or more divisional
applications.
