Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This in~ention relates to a method ~or depilating
slaughtered livestock, especially pigs, whereby the carcass is
first of all subjected to a warm water treatment, then roughly
depilated by means of beating and scraping tools while simultan-
eously being rotated about its longitudinal axis, and after com-
pletion of this rough depilating process the remaining fine hairs
are removed using a burner.
Such a method is known ~rom German Patent 20.47.323. In
this method, in order to shorten the depilating period, the carcass
is flamed over its entire length during the rough depilating pro-
cess carried out by the beating and scraping means. This is based
on the idea that the heat of the flame causes the hairs to be
erected thereby facilitating the removal of hairs rom the skin
using the beating and scraping means. ~lowever, practice has shown
that such use of a flame generally shortens the hairs to an
extent that they can no longer be removed from the skin by the
beating and scraping means. Accordingly, an increased volume of
hairs has to be burnt away and therefore a much greater volume of
hair residue than is desirable will remain in the skin.
It is known in the prior art to ~irst remove the long
hairs completely using beating and scraping means, i.e. carrying
out a complete rough depilating process and to then remove the
remaining fine hairs using a hand operated burner.
The method of German Patent 20.47.323 resu]ts on the one
hand in a time saving in relation to the last mentioned method.
On the othe~ hand~ ho~eYex~ it results in a decrease in quality,
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because not only more hair residues than are desirable remain in
the skin, but also the constant flame intensity over the entire
length of the carcass will result in local overheating. It is
more difficult to depilate the head section of a pig than the
belly section and therefore the use of a flame jet extending over
the entire length of the carcass (taking into account the fact
that depilating the head portion is more dif-ficult and that more
hair than after complete rough depilating has to be burnt) will
cause the belly section to split because of overheating.
According to the present invention there is provided a
method for depilatingslaùghtered livestock comprising: subjecting
the carcass to a warm water treatment; roughly depilating the
carcass by means of beating and scraping tools while simultaneously
rotating the carcass about its horizontal longitudinal axis; and
removing the remaining fine hairs using burner means operative over
the entire carcass while rotation of the carcass is continued, said
burner means acting on various zones of the carcass with differences
in operating time and/or intensity.
The invention is thus based on the idea, which is in it-
self known from German Offenlegungsschrift 12.98.894, that it is
preferable for the carcass to be roughly depilated completely using
mechanical beating and scraping means, because in that case the
majority of the hairs are removed from the skin, so that no
residues remain.
Furthermore, the knowledge that it is possible to remove
the remaining ~ine hairs using a burner plays a part in the in-
7~. vention. In the prior art, it is known to remove the ~ine hairs
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after the rough depilating process using ~ hand operated burner.
Such treatment however is very arbitrary and is either insufficien-t
or results in local overheating. The person carrying out this
treatment is not able to see exactly what he is doing during the
burning process and is only able to see rom the resul-t that he
has to do more or that he has overdone it. If he has overdone it
the damage is beyond remedy. Since according to the invention the
operating time and/or the intensity of the burners acting on
different sections of the body are adapted to the local circum-
stances, the possible damage which may be caused in using handburners will be avoided. Removing hairs from the head portion is
more difficult than removing hairs from the tail portion which in
turn is more difficult than removing hairs from the belly or
central portion. Accordingly, one may use burners of equal flame
intensity but which are controlled to operate during varying time
periods or one may use burners of different flame strength.
Experiments, carried out on a certain type of animal, will give -
data about the desired operating time and/or flame intensity and
parameters can be maintained continuously without the possibility
of human error.
According to one embodiment of the invention a carcass is
treated with at least one burner which is pivotable around a fixed
shaft and is controllable such that the flame affects both ends of
the carcass with greater intensity or acts on both ends of the
carcass longer than on the central portion of the carcass. In
this e~b~d,iment, a,t ~o~h end~ o~ the sWinging movement, that is,
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where the direction o~ moveMent is xevexsed, e~ther the intensity
of the flame should be increased or the operating time of the
burners should be increased.
It ls also possible to use two pivotiny burners, one for
the front half o~ the carcass and one for the rear half. Such
burners would reverse their swinging movements near the central
portion of the cascass ~aster than at the reversing points near
the end portions of the carcass.
According to another embodimentl one uses a burner which
is movable parallel to the longitudinal axis of the body. The
burner is moved bac~ and forth with such a ~7arying speed that the
flame action time at the head and tail portions of the carcass is
longer than the action time at the central portion of the carcass.
The nature of the movement of the burner will cause it to act more
intensively at the end portions of the animal in comparison to the
central portion. However, one may also increase the flame strength
near the reversing points of the movement.
According to a further embodiment of the invention, a
plurality o~ stationary burners are used and separate burners or
groups of burners are controlled by a timer or are arranged to
function with different intensity.
- For removing the fine hairs on the head portion usually
five or six rotations of the carcass are necessary. For the tail
portion, four to five rotations are necessary and for the central
portion three or four. Variation in operating time or flame
~ntensity ~here~Q~e xe~s~ul~s ~n enexg~ ~avings.
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According to another aspect of the lnvention there is
provided an apparatus ~or depilatin~ slaughtered livestock com-
prising: a grate or supporting a carcassj a drive shaft arranged
underneath said grate and supporting beating and scraping tools
such that they extend through said grate between bars of said
grate; burner means arranged above said grate; and control means
~or controlling said burner means so as to act on various zones
of the carcass with differences in operating time and/or intensity.
The apparatus may comprise one burner which is pivotable
about a horizontal axis transverse to the axis of the drive shaft.
The burner pivots about a fixed point and is controlled by control
mechanisms, which are known, so that the flame action has the
desired effect on the different portions of the carcass.
Alternatively, one could use two separate pivotable
burners which operate on the fr~nt and rear halves of the body
respectively.
According to a another embodiment a guide rail supporting
a burner is installed above the grate. The burner is movable back
and forth along a path parallel to the axis of the drive shaft and
is controlled so that it operates longex on the head and tail
portions than on the central portion. Because of the nature of the
movement, the burner will operate longer at the reversing positions
than in the centra~ section. If necessary, one could also vary
the speed of the burner. Furthermore, one could increase the
intensity of the flame at the end portions of the carcass, for
lnstance( b~ us~n~ an o~exatin~ lever of a gas valve cooperating
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with a tenslon element W~ich would bring the lever back into the
initial position by means of spxing pressure.
~ ccording to a further embodiment, one may use stationary
burners functioning with varying pressures and/or varying openings
or Lunctioning during varying operating times determined by a
timer. It is for instance possible to first start the burners
operatin~ on the head section and approximately one rotation later
open the gas supply to the bllrners operating on the rear section
and again one rotation later starting the burners operating on the
central section. All burners can be closed simultaneously.
The inven-tion will be explained in more detail with
reerence to the drawings.
Figure 1 illustrates schematically a front view of a
first embodiment of a system according to the invention.
Figure 2 illustrates schematically a side view of the
system according to Figure 1.
Figure 3 shows also schematically a front view of another
embodiment.
Figure ~ shows schematically a side view o~ the embodiment
o~ Figure 3.
Figure 5 shows schematically a front view of another
embodiment.
Figures 6 and 7 show front views of embodiments with
stationary burners.
The system shown in Figures 1 and 2 comprises a frame 1
supporting a sha$t 2 ha,Ying flexible beating and scraping means 3.
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Frame 1 carries a grate 5 consistin~ of bars, the central part
of which is bent downwards at 4 to ~orm a pit for receiving khe
carcass of a pig.
The beating and scraping means are in the form of rods
and are able to move between the bars of the grates during their
rotation in the direction of arrow 7. ~ second grate 9 with
curved bars extends from the grate 5 upwards such that the carcass
is supported by the bars of grate 5 and the bars of grate 9 and is
rotated by the beating and scraping means. This is a known
technique which is discussed for instance in German Patent
20~37 323. A further grate 8 is adapted to guide the carcass
into the system. In the upper part of the frame, a rail track 12
carries a movable burner 11 having a flame mouthpiece 10. The
burner is moved back and forth by means o~ an electric motor 13
which may, for instance, drive the burner 11 by means of a chain
or a threaded spindle. The flame 14 is directed downwards. If
the burner 10, 11 is driven with constant speed, the deceleration
and acceleration during the reversing of direction at the ends
of the rail track 12 will result in a prolonged flame effect at
th~se~positions.
Figure 1 shows a burner near both end positions.
In the embodiments of Figures 3 and 4, two burners 15
and 16 are rotatably carried on transversal axes 18 and 19. Flames
20 acting on the area covered by burners 15, 16, as shown in
Figure 3 can be controlled such that they act in the illustrated
end position fo~ a lon~er pe~iod than in the non-illustrated other
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end position. ~ns~ead of opposed swinging movements/ the burners
may moYe synchronously so that the ~lames remain parallel in all
circumstances. ~n that case one avoids overlapping of the flames
of both burners in the central area.
Figure 5 shows an embodiment having only one burner 21,
which may swing around a centrally positioned shaft 23. The shaft
can be driven such that the flames 25 act longer at the reversing
points of the swinging movement (at which point the flames are at
the greatest distance from the carcass) than in the central area
and pass the central area at increased speed. Such a ~ovement may
be controlled using known ~means, for instance cam elements or
eccentric elements.
In the embodiment o~ Figure 6, a series of stationary
burners are divided into a first group 26, a second group 27 and
a third group 28. All the burners are connected to a gas pipe 29
having a main stop cock 30, a stop cock 31 on branch 32 shunting
the central group of burners 28 and a stop cock 33. All the stop
cocks can be controlled by time control mechanisms, which are
themselves known/ such that first of all the stop cock 30 will be
opened activating the burners 26, whereafter the stop cock 31 will
be opened activating the burners 27 and thereafter the stop cock
33 will be opened for the burners 28, whereafter all the stop cocks
will be closed simultaneously.
Of course it is also possible to close the stop cocks at
di~ferent times.
F~u~e 7 s.ho~w~s a yariant o~ the embodiment oE Figure 6,
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which variant comprises three grou~s of bu~ners, 34, 35, 36 all
connected to the same gas pipe 37 With stop cock 3g. The burners
35 have the smallest mouthpiece diameter, the burners of the
group 36 have a somewhat larger mouthpiece diameter and the burners
of the group 34 have the largest mouthpiece diameter~ The 1ame
strength is therefore adapted to the local circumstances.
In general, when one is depilating slaughtered livestock,
especially pigs, in a production line the dimensions of the
animals do not vary significantly. Skin and hair characteristics
are also in general comparable.
Some production lines treat and depilate 500 to 1000 pigs
per hour. With such large production numbers and the very short
period of time that each carcass spends in the depilating machine,
the continuous maintenance of fixed parameters for the process in
which the fine hairs are removed by means of flames is of extremely
great significance. This is for the first time completely possible
with the method and system according to the invention thereby
avoiding a local decrease in the quality of the meat.
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