Apparatus for peeling and transferring an animal hide to processing

A device is described for separating animal skin and for transferring it to further processing through a conveyance channel by using pressure difference. The device comprises a pulling device (3) for separating the skin (2) from the animal carcass (1) and for feeding it to the forward end of a conveyance channel (7), and means (8-10) to generate pressure difference between the ends of the conveyance channel and for separating the conveyed skin (2) form the portage air. According to the invention, the pulling device (3) that engages the other end of the skin (2) further comprises means (4, 5, 12) for feeding the skin (2) to the feed hopper (6) at the forward end of the conveyance channel (7) and for separating it from the pulling device (3) for suction conveyance. In this case, the feeding and separating means (4, 5, 12) are preferably set above the feed hopper (6) so that the skin (2) can be dropped to the feed hopper (6) for the suction conveyance.

The invention is related to a device for separating animal skins, such as 
cow or horse skins, and for transferring them through a conveying passage, 
by using pressure difference, to further processing and, particularly, to 
a device that comprises a pulling device for separating the skin from the 
carcass of the animal and for feeding it to the forward end of the 
conveying passage, and means for generating pressure difference between 
the ends of the conveying passage and for separating the conveyed skin 
from the conveying air. 
The term "skin", in this context, refers to the skin of an animal such as a 
cow, horse or the like that is stripped in a slaughterhouse. The term 
"stripped" refers to the stripping of the skin from the carcass of the 
animal in question. 
Existing slaughterhouses are designed to comprise two storeys and the 
treatment of skins generally takes place downstairs beside the 
skin-pulling device. In such a storey solution the skin is directly 
dropped downstairs from the roll of the skin pulling device, away from the 
premises of the slaughterhouse. However, the trend today is to build 
advantageous one-storey slaughterhouses, whereby it is not possible to 
utilise gravity in transferring skins downstairs and, therefore, dirty 
skins have to be conveyed from the slaughterhouse to the skin department. 
The transportation of skins sets limitations on the lay-out planning since 
it is generally not possible to locate the skin department beside the 
position of skin separation because of other operational starting points. 
The transportation of skins by long and inconvenient conveyors is not only 
insanitary and expensive but also requires maintenance. furthermore, the 
conveyors impede passenger traffic. 
The gear for skin transporation known from before includes different 
conveyors such as belt or slat conveyors and the blowing by overpressure 
along a tabe (pneumatic cannon). It is difficult to automate the equipment 
for transportation by pneumatic cannon; it requires the building of a hole 
over 2 metres deep in the floor so that the skin can be lowered directly 
from the roll of the pulling device to the transmit arrangement of the 
funnel-like cannon. The above-mentioned hole structure is insantary and 
difficult to implement technically, particularly in the existing 
slaughterhouses. The pneumatic cannon placed on the floor requires at 
least one worker to precondition the skin for transportation. In the 
preconditioning, the skin is folded into an elongated fold so that it is 
easy to push to the elongated funnel tube of the cannon transmit 
arrangement and it slides well in transit tube without causing blockage. 
All these transfer methods and equipment are very expensive and 
impractical. 
The disadvantages of the above-mentioned devices are now eliminated by 
transferring skins in a channel by using pressure difference, ie., by 
suction conveyance mainly as defined in the appended claims. In the 
solution according to the invention, the transfer of skins is automated so 
that it does not require manpower. The transfer by underpressure (vacuum) 
is a closed transfer system, hygienic and flexible. Consequently, the 
location of further processing can be selected according to other 
productional requirements. 
The device according to the invention for separating animal skins and 
transferring them through a conveyance channel to further processing can 
be used to apply suction conveyance because the pulling device that 
engages the other end of the skin comprises means for dropping or lowering 
the skin, with its opposite end in front, to a feed hopper at the forward 
end of the conveyance channel, and means for separating the skin from the 
pulling device for the said suction conveyance. The feeding and separating 
means are preferably located above the feed hopper, whereby smaller and 
lighter skins can be dropped to the feed hopper whereas larger and heavier 
skins are gradually lowered, with the opposite end in front, to the feed 
hopper, in a controlled manner, before the other end is detached from said 
means. 
In a preferred embodiment of the invention, the inner diameter of the 
conveyance channel is more than about 200 mm, preferably at least about 
210 mm, for example 210-270 mm whereas the amount of vacuum in the suction 
conveyance is at least 40%. The forward end of the conveyance channel is 
preferably slightly flattened out, for example, oval. 
In a preferred embodiment of the invention, the pulling device is set 
upwards above an open feed hopper, whereby it comprises a vertically 
movable pulling roll. At least one zipper provided with a fastening loop 
and intended to be attached to the other end of the skin, and at least one 
release member for releasing the fastening loop from the skin can be wound 
on the pulling roll after the skin has been fed gradually and in a 
controlled manner to the feed hopper with its opposite end in front. The 
release member is preferably a release chain wound on the pulling roll in 
the opposite direction with respect to tie zipper. This solution can be 
used to quickly and effectively release the skin for the suction 
conveyance. 
The tail of the conveyance channel can be connected to a separating chamber 
which again is connected to an underpressure centre to maintain pressure 
difference between the ends of the conveyance channel and which comprises 
a lower part with an openable bottom door for the discharging of the thus 
conveyed skin from the device for filter processing. A vacuum battery can 
be used as the underpressure centre.

The transfer tube of the skin is marked reference number 7. Feed hopper 6 
is attached to the forward end of the transfer tube and skin 2 is fed to 
the feed hopper together with air. Separation chamber 8 is provided at the 
opposite end of transfer tube 7 in which skin 2 is separated by 
centrifugal force from the portage air and drops down to the bottom of 
separation chamber 8. Portage air is sucked from separation chamber 8 
through tube 9 to underpressure centre 10. After the transportation, 
bottom door 11 of separation chamber 8 is opened, whereby skin 2 drops 
down to the collection point for further processing. 
As FIG. 3 more closely presents, feed hopper 6 is located so that, when 
discharging skin 2 from its pulling roll 4, skin pulling device 3 feeds 
the skirt of the skin to transfer tube 7 along with air motion. Skin 2 is 
pulled to transfer tube 7 by suction at the same speed as skin pulling 
device 3 discharges skin 2 from its pulling roll 4. The simultaneous 
suction both keeps skin 2 straight and shapes it into the form of transfer 
tube 7, not letting skin 2 pile up and block the junction between feed 
hopper 6 and transfer tube 7. Upon skin 2 fully unrolling from pulling 
roll 4 through feed hopper 6 to transfer tube 7, release chains 12 of the 
pulling device are tensioned and release skin 2 from chain links 5' of 
zipper 5. After having been released from links 5' of zipper 5 of skin 
pulling device 3, skin 2 is moved by suction conveying along tube 7 to 
separation chamber 8. The suction is discontinued and bottom door 11 of 
separation chamber 8 is opened and skin 2 is dropped to the collection 
point. 
Pulling roll 4 of skin pulling device 3 moves to its upper position for the 
next pulling of skin. 
EXAMPLE 
A transfer device according to FIGS. 1-3 was built, comprising an 8000 
litre container (underpressure battery) as unde pressure centre 10, from 
which 40% air had been sucked out, i.e., its vacuum was 400 mbar. The 
underpressure battery was connected to separation chamber 8 by a 100 mm 
diameter tube 9 comprising a quickly-openable ball valve. The inner 
diameter of transfer tube 7 was 267 mm and the length of tube 7 was 12 m, 
including 2.5 mm of delivery lift. This tube size enabled an easy feeding 
of skin 2 to feed hopper 6. when the living weight of cow was lower than 
700 kg and when a vacuum of at least about 400 mbar was used in the 
suction conveying. 
With a living weight of cow increasing to over 1000 kg, skin 2 is so large 
and heavy that it must be fed to feed hopper 6 with the above-mentioned 
tube size gradually in a controlled way. In the device according to the 
invention, the feeding of the skin to the feed hopper can be cared out 
easily with success. 
An optimal tube size without controlled feed (the skin is sucked to the 
tansfer tube in a bundle or a ball) for Finnish cow skin is about 210 mm, 
when the amount of underpressure air, 40% of a complete vacuum, is about 
5000 volumetric litre. With the length and diameter of the transfer tube 
increasing, the amount of underpressure air increases, correspondingly. 
When the underpressure is smaller, the diameter of the tube must be 
correspondingly larger. 
The shape of the forward end of transfer tube 7 connected to feed hopper 6 
also influences the blocking sensitivity (the vault-forming) of the 
transfer channel. When a flattened forward end of the tube was used, i.e., 
the forward end was in the form of an ellipse, the above-mentioned 
sensitivity to block was decreased considerably. 
It is advisable to provide the underpressure centre 10 with a 2000-5000 
litre underpressure battery to exert a sufficient charging stroke to pull 
the skin to transfer tube 7, simultaneously preventing by-pass flow 
between the skin and the wall of the tube.