A METHOD AND AN APPARATUS FOR CUTTING FREE AND REMOVING THE RECTUM OF AN ANIMAL TO BE SLAUGHTERED, PREFERABLY PIGS

Abstract: A method of cutting free and removing the rectum of an animal (1) to be slaughtered, whereby the rectum is cut free by means of a rotating tubular knife (34) being moved into the animal from the back and substantially coaxially with the centre line of the rectum while being guided by means of a pin inserted in the rectum. The rectum cut free is retained by the knife (34) and is pulled out of the animal in a substantially horizontal direction towards the ventral side (13) of the animal, while the ham (14) is simultaneously being cut through between the hind legs of the animal. The rectum is subsequently left hanging downwards over a side of a protecting shield (10) facing away from the animal to be slaughtered. In an apparatus for carrying out the above method, the rotating tubular knife (34) comprises a thread on the inner side, and the pin comprises an external thread, said threads being cut in opposite directions with the result that a reliable retaining of the rectum cut free is ensured during the cutting procedure.

Description: Title: A Method and An Apparatus for Cutting Free and Removing the Rectum of an Animal to be Slaughtered. Pre¬ ferably Pigs . Technical Field The invention relates to a method of cutting free and removing the rectum of an animal to be slaughtered, pre¬ ferably a pig, whereby the rectum is cut free by means of a rotating tubular knife being moved into the animal from the back and substantially coaxially with the centre line of the rectum while being guided by means of a pin inserted in the rectum, whereafter the rectum cut free is retained by the knife and thereby pulled out of the animal. The invention relates furthermore to an ap¬ paratus for carrying out the above method. Background Art It is known inter alia from DK-PS No. 156,808 to cut free the rectum, the so-called fatty end, of an animal to be slaughtered by means of a rotating tubular drill or a rotating tubular knife, where said knife is placed opposite the rectum of the animal in such a manner that the axis of rotation of the knife is placed in extension of the centre line of the rectum and the spine of the animal. Subsequently, the rotating drilling pipe is moved forwards, said movement being guided by means of a pin placed in the tubular drill and being inserted in the anus. According to DK-PS No. 156,808 the drill is removed after the cutting procedure. Attempts at pulling out the rectum in extension of the centre line thereof are also known, where said rectum is retained outside the animal on the back of the animal while the remaining intestinal portions are cut free. A condition for pulling out the rectum in extension of its centre line is that the rectum is so resilient that it can be kept intact outside the animal. It turned out, however, that the resilience of the rectum varies much from animal to animal, especially in connection with pigs, with the result that rupture of said rectum often arises. The latter applies particularly often to sows. Both when the rectum is left inside the animal after the cutting procedure and when attempts are made at pulling out said rectum whereby said rectum ruptures, a risk exists of the visceral contents sieving out into the meat and thereby contaminating said meat. Especially the latter contamination caused by sieving visceral contents turned out to present severe problems of bacteria, such as Salmonella and Yersenia, in connection with meat from the bacon factories. Accordingly, the importance of avoiding in any possible way a sieving of visceral con¬ tents is recognized. The rectum cut free cannot there¬ fore be left free in the animal after the cutting free procedure. Nor should rupture of the rectum be allowed to arise during the attempts at pulling it backwards relative to the hind part of the animal and retaining it in the drill until the remaining portion of the in¬ testinal portions have been cut free. Although the re¬ maining intestinal portions are cut free without causing any sieving of the visceral contents thereof, a risk exists that some of said visceral contents nevertheless escapes in connection with the releasing of the rectum from the drill. Description of the Invention Accordingly, it is the object of the invention to pro- vide a method which in a highly reliable manner avoids contaminating visceral contents from escaping during the slaughtering procedure. The method according to the invention is characterised in that the rectum cut free is pulled out of the animal in a substantially horizontal direction towards the ven¬ tral side of the animal while the ham is simultaneously being cut, and that the rectum is subsequently left hanging downwards over a side of a protecting shield facing away from the animal to be slaughtered. In this manner the rectum avoids being subjected to a tension, which it cannot often stand up to, and in addi¬ tion it is carried downwards and left on a location where the visceral contents cannot come into contact neither with the animal nor the slaughterman. During the pulling out movement, the attachments usually resisting the pulling out of the rectum in a rearward direction are easily torne loose without thereby tearing apart the rectum. The apparatus for carrying out the method comprises a tubular rotatable knife coaxially surrounding a pin and comprising a cutting edge at the front end, whereby the rear end opposing the cutting edge is provided with means for providing a vacuum suction. The apparatus is according to the invention character¬ ised in that the pin is stationary, and that the inner side of the tubular knife and the outer side of the pin are provided with a thread being cut in opposite direc¬ tions . The resulting apparatus ensures a reliable cutting free and retaining of the rectum during the pulling out move¬ ment because the oppositely threaded threads on the ro¬ tating knife and the stationary pin pull the rectum in an efficient manner into the interior of the apparatus, where said rectum is retained partly by means of vacuum and partly by the engagement with the threads during the forward pulling to the protecting shield. The threads must, of course, be of such a shape that they do not tend to cut a hole in the rectum. According to the invention, the tubular knife may be shaped on the inside with a conical transition portion narrowing away from the cutting edge and continuing into a cylindrical portion carrying the internal thread. The resulting squeezing of the rectum about the pin is very reliable at the same time as the effect of the vacuum is efficiently supported. The vacuum effect is additionally supported in an advantageous manner by the pin according to the invention being shaped with a conical transition portion expanding away from the free end of the pin and continuing into a cylindrical portion carrying the ex¬ ternal thread. Finally according to the invention a fixed knife may be provided outside the tubular rotatable knife, said fixed knife automatically cutting the ham while the rectum cut free is being pulled out towards the ventral side of the animal. Before the described apparatus is used, the ab¬ domen of the animal has been cut up in a conventional manner, and the animal has been opened up to the inguin- al bone, which has preferably also been cut through be¬ fore the apparatus is used. After the rectum has been cut free, the ham need only be cut in two in order to allow the rectum to be pulled forwards onto the ventral side while being retained by the apparatus. The latter procedure is carried out in an easy and fast manner by means of the fixed knife. If desired, the inguinal bone can be cut simultaneously with the above procedure be¬ cause said bone comprises a relatively easily cutable cartilage portion in the centre thereof. The latter cut- ting requires, however, rather skilled slaughtermen. Brief Description of the Drawings The invention is described in greater detail below with reference to the accompanying drawings , in which Fig. 1 is a diagrammatic view of an animal to be slaughtered, said animal being slung in the hind legs ready for having the rectum cut free in accordance with the present invention by means of a preferred embodiment of the apparatus according to the invention, one hind leg of said animal to be slaughtered being omitted for the sake of clarity, Fig. 2 is a diagrammatic sectional view on a larger scale of a portion of the animal during the cutting free of the rectum, only part of the apparatus for cutting said rectum free being diagrammatically shown, partly in section, Fig. 3 corresponds to Fig. 2, but during the forward pulling of the rectum on the ventral side of the animal, and Fig. 4 is an axial, sectional view on a larger scale through the apparatus of Fig. 1, whereby parts have been omitted for the sake of clarity. Description of the Preferred Embodiments of the Inven¬ tion The animal to be slaughtered shown in Fig. 1 is a pig 1 ready for being subjected to a cutting free of the rec¬ tum. The abdomen of the animal to be slaughtered has in advance been cut up and opened to the inguinal bone 2 indicated by a dotted line in the drawing. The cutting free of the rectum is carried out by means of an appara¬ tus 3 described in greater detail below. The apparatus 3 is connected to a hose for the feeding of vacuum, pres¬ surized air, hot water, and cold water, a hose 5 for pressurized air, as well as an electric wire 6. The ap- paratus 3 is slung in a line 7 being unwound from a storing spool 8. A mirror 9 is provided behind the ani¬ mal opposite the hind portion of said animal, said mir¬ ror being used by the slaughterman during the handling of the apparatus 3. The rectum of the pig 1 is cut free opposite a platform 9 of such a height relative to the pig that the slaught¬ erman can cut the rectum free at chest height. A pro- tecting shield 10 is provided between the slaughterman and the pig 1, said shield extending obliquely downwards from a guide pipe 11 and comprising a drain 12 at the bottom. Before the method according to the invention is initiat- ed, the pig 1 slung in its hind legs has been subjected to a slaughtering process ending with a cutting up of the abdomen, cf. the reference numeral 13 in Figs. 2 and 3. The abdomen of the pig 1 slung up has been cut to the ham 14 between the hind legs of said pig, the ham abut- ting the rectum of the pig. In addition to the cutting of the abdomen 13, the inguinal bone 2 is also cut. Subsequently, the cutting free of the rectum is initiat¬ ed by means of the apparatus 3. As shown in Fig. 4, the apparatus comprises a carrying frame 15 carrying an air motor 16 at one end. The air motor is adapted to be driven by means of pressurized air fed through the hose 5, cf. Fig. 1. The air motor 16 comprises an output shaft 17 carrying a toothed pulley 18 arranged in the interior of the carrying frame 15. A toothed belt 19 extends about the toothed pulley, said toothed belt ex¬ tending through the carrying frame 15 to the opposite end of said frame where it engages a driven toothed pul¬ ley 20. The latter toothed pulley 20 is permanently con¬ nected to a rotor 22 by means of a key 21, said rotor being rotatably journalled inside a substantially cylin¬ drical bearing housing 23 by means of ball bearings 24 and 25. The bearing housing 23 is supported by and per¬ manently connected to the carrying frame 15 in a manner not described in greater detail. The bearing housing 23 is at one end closed by means of a cover 26. The cover 26 is centrally fixedly connected to a hollow shaft 27 coaxially extending through the rotor. The shaft 27 comprises at the end adjacent the cover 26 an internal thread 28 for the securing of the hose 4 for vacuum, pressurized air, and hot and cold water. The hollow shaft 27 extends, as mentioned, coax¬ ially through the rotor 22 and is connected by means of an external thread to a stationary pin arranged inside the apparatus. The pin 30 comprises an inner tubular part 31 of a circular cross section and with a through hole 32 provided with an internal thread. The inner part 31 of the pin is at the inner end screwed onto the hol¬ low shaft 27 by means of the latter thread, whereas the opposite end of said inner part is closed by means of a second, outer part 33 in form of an annular solid bar provided with an external thread, which is to engage the thread in the through hole 32. The outer part 33 is smoothly rounded at the free end facing away from the inner part 31. A tubular knife 34 is provided coaxially about the pin, said knife at one end being screwed fixedly onto the rotor 22 by means of co-operating threads 35. The tubu¬ lar knife 34 carries a circular cutting edge 36 at the end opposite the rotor. A free, rotationally symmetrical passage is provided about the pin 30 from the free end of said pin 30 and past the inner part of said pin to the portion of the hollow shaft 27 adjacent said pin 30. The latter portion of the hollow shaft 27 is surrounded by an inner circum¬ ferential recess 38 in the rotor 22. The bottom of the recess is closed by means of a gasket 39 sealingly abut¬ ting both the hollow shaft 27 and the rotor 22. Openings 39, 40, 41, and 42 are provided opposite the interior of the passage 37 about the pin 30 in the area about the recess 38 in the rotor 22. The openings per¬ forate the wall of the hollow shaft 27 and form thereby an open connection to the interior of the hollow shaft 27 and consequently to the hose 4. The tubular knife 34 is at the end abutting the cutting edge 36 internally shaped with a cylindrical portion 43 abutting an area 44 which narrows conically to an inner cylindrical area 45 shaped with an internal thread 46. The outer part of the pin is of a circular cross section and extends substantially parallel to the inner cylin¬ drical area 43 of the tubular knife 34 until said cylin¬ drical area 43 abuts the conical area 44. The outer end of the inner tubular part 31 of the pin 30 is situated at about the same position as the conical area 44. The outer end of the inner tubular part 31 of the pin 30 comprises a conically shaped area 47 of subs antially the same axial extent as the inner conical area 44 of the tubular knife 34. The conical area 47 expands in¬ wardly and continues into an inner cylindrical area 48 of almost the same axial extent as the inner cylindrical area 45 on the tubular knife 34. The inner cylindrical area 48 on the pin 30 is shaped with an external thread 49. The thread 49 on the pin 30 is cut in opposite direction relative to the thread 46 on the inner side of the tu¬ bular knife 34. A plane knife 51 is secured on the outer side of the bearing housing 23 by means of a substantially radially projecting bracket 50. The plane knife 51 extends sub- stantially parallel to the axis of the tubular knife 34 a suitable distance forwards to the vicinity of the cut¬ ting edge 36 thereof. When the apparatus 3 is running, the rotor 22 is caused to rotate by means of the motor 16 through the toothed belt 19, and consequently the tubular knife 34 is also caused to rotate. The pin 30 coaxially arranged inside the tubular knife 34 remains stationary, the free end of said pin projecting slightly outside the cutting edge 36 of the knife 34. A handle 52 is provided for facilitating the handling of the apparatus 3, said handle comprising switches not shown in greater detail for the control of the running of the motor 16 and the feeding of vacuum, pressurized air, hot or cold water to the interior of the hollow shaft 27 through the hose 4. When carrying out the method according to the invention, the apparatus 3 is moved forwards towards the anus of the animal to be slaughtered, vacuum being fed to the hollow shaft 27. The pin is by means of the mirror 9 inserted in the anus of the animal, and the tubular knife is moved close to the animal in such a manner that a vacuum can be established in the interior of the tubu¬ lar knife. Subsequently, the tubular knife is caused to rotate, and as illustrated in Fig. 2, the knife 34 is then moved into the animal coaxially with the rectum. As a result, the rectum is cut free together with a surrounding fatty layer, the reason why the portion cut free is also re- ferred to as the fatty end. The fatty end is diagram¬ matically shown at the reference numeral 53 in Fig. 2. While the tubular knife 34 continues to rotate, the fat¬ ty end 53 engages the internal thread 46 on the tubular knife 34 with the result that the suction effect of the vaccum is supported. The oppositely cut external thread 49 on the pin ensures an additional retaining and guid¬ ing of the inner side of the rectum forwards towards the interior of the apparatus 3. The threads 46 and 49 in¬ side the apparatus 3 ensure together with the narrowed portion of the passage 37 about the pin 30 both a good retaining of the fatty end 53 and an efficient closing of the rectum in such a manner that nothing sieves out of said rectum. When the fatty end 53 has been cut completely free and is placed in the bottom of the apparatus 3, said appara¬ tus is pulled substantially horizontally forwards to¬ wards the ventral side of the animal. During the latter movement, the ham 14 is cut in two by means of the knife 51. Subsequently, the apparatus is moved downwards, cf. Fig. 3, until the rectum 54 is positioned immediately above the guide pipe 11, cf. Fig. 3 too. During the movement from the cutting free location and forwards to the area immediately above the guide pipe, the slaughterman must, of course, be very careful to main- tain the tubular knife 34 and the pin 30 substantially coaxially with the rectum 54 in such a manner that the rectum or the fatty end 53 is not pressed out into con¬ tact with the cutting edge 36 and is damaged. Attach¬ ments 55 between the rectum 54 and the animal are torne loose during the pulling out movement. When the rectum 54 is positioned above the guide pipe 11 in the position shown in Fig. 3, the feeding of vacuum is interrupted to the apparatus and a pressurized air valve is opened for a short period. As a result the fat- ty end is released from the apparatus 3 and positions itself in such a manner that it hangs downwards over the guide pipe 11 and along the side of the protecting shield 10 facing away from the animal. Possible escapes of visceral contents flow down the protecting shield and are collected in the drain 12. While the fatty end 53 is hanging over the guide pipe 11, the animal can be moved forwards for a cutting free of the remaining intestinal portions without risking escapes of visceral contents coming into contact with the animal or the slaughterman. The tubular knife 34 of the apparatus 3 can remain ro¬ tating during the movement from the cutting free loca¬ tion to the release location above the guide pipe 11, said retaining being improved by the rotation. After the cutting free, the apparatus is advanced for sterilisation, the interior of the apparatus being ste¬ rilised by means of hot and cold water fed through the hose 4. The apparatus is made of suitable materials easy to clean, and in dimensions conventionally used within the field in question. The internal thread on the tubular knife is according to a preferred embodiment of the in¬ vention of an inner diameter of 44 mm. The external thread 49 on the pin 30 is of an outer diameter of 27 mm. Both threads are trapezoidal with rounded edges and a pitch of 6 mm and a depth of 2 mm. The thread 46 on the tubular knife 34 is left-handed. The outer cylindrical area 43 on the inner side of the tubular knife 34 is of an inner diameter of 56 mm, whereas the outer part of the pin is of a diameter of 12 mm. The length of the conical areas 44 and 47 on the tu¬ bular knife 34 and the pin 30, respectively, is approxi¬ mately 40 mm. The invention has been described with reference to a preferred embodiment. Many modifications can be carried out without thereby deviating from the scope of the in¬ vention. The threads may for instance be of other shapes beyond the one described, and the protecting shield with the associated guide pipe and drain may be shaped in another manner.

Claims: Claims . 1. A method of cutting free and removing the rectum of an animal to be slaughtered, preferably a pig, whereby the rectum is cut free by means of a rotating tubular knife being moved into the animal from the back and sub¬ stantially coaxially with the centre line of the rectum while being guided by means of a pin inserted in the rectum, whereafter the rectum cut free is retained by the knife and thereby pulled out of the animal, c h a r a c t e r i s e d in that the rectum (53) cut free is pulled out of the animal in a substantially ho¬ rizontal direction towards the ventral side (13) of the animal while the ham (14) is simultaneously being cut, and that the rectum is subsequently left hanging down- wards over a side of a protecting shield (10) facing away from the animal (1) to be slaughtered. 2. An apparatus for carrying out the method as claimed in claim 1, said apparatus comprising a tubular rotat¬ able knife coaxially surrounding a pin and comprising a cutting edge at the front end, whereby the rear end op¬ posing the cutting edge is provided with means for pro¬ viding a vacuum suction, c h a r a c t e r i s e d in that the pin (30) is stationary, and that the inner side of the tubular knife (34) and the outer side of the pin (30) are provided with a thread (46 and 49, respective¬ ly) being cut in opposite directions. 3. An apparatus as claimed in claim 2, c h a r a c ¬ t e r i s e d in that the tubular knife (34) is shaped on the inside with a conical transition portion (44) narrowing away from the cutting edge and continuing into a cylindrical portion (45) carrying the internal thread (46). 4. An apparatus as claimed in claim 2 or 3, c h a r ¬ a c t e r i s e d in that the pin (30) is shaped with a conical transition portion (47) expanding away from the free end of the pin (30) and continuing into a cylin¬ drical portion (48) carrying the external thread (49). 5. An apparatus as claimed in claim 2, 3 or 4, c h a r a c t e r i s e d in that a fixed knife (51) is provided outside the tubular rotatable knife (34), said fixed knife automatically cutting the ham (14) while the rectum (53) cut free is being pulled out towards the ventral side (13) of the animal. AMENDED CLAIMS [received by the International Bureau on 26 June 1992 (26.06.92); original claim 2 amended; other claims unchanged (2 pages)] 1. A method of cutting free and removing the rectum of an animal to be slaughtered, preferably a pig, whereby the rectum is cut free by means of a rotating tubular knife being moved into the animal from the back and sub¬ stantially coaxially with the centre line of the rectum while being guided by means of a pin inserted in the rectum, whereafter the rectum cut free is retained by the knife and thereby pulled out of the animal, c h a r a c t e r i s e d in that the rectum (53) cut free is pulled out of the animal in a substantially ho¬ rizontal direction towards the ventral side (13) of the animal while the ham (14) is simultaneously being cut, and that the rectum is subsequently left hanging down- wards over a side of a protecting shield (10) facing away from the animal (1) to be slaughtered. 2. An apparatus for carrying out the method as claimed in claim 1, said apparatus comprising a tubular rotat¬ able knife coaxially surrounding a pin and comprising a cutting edge at the front end, whereby the rear end op¬ posing the cutting edge is provided with means for pro¬ viding a vacuum suction, c h a r a c t e r i s e d in that the pin (30) is stationary, and that the inner side of the tubular knife (34) is provided with a thread (46). 3. An apparatus as claimed in claim 2, c h a r a c ¬ t e r i s e d in that the tubular knife (34) is shaped on the inside with a conical transition portion (44) narrowing away from the cutting edge and continuing into a cylindrical portion (45) carrying the internal thread (46). 4. An apparatus as claimed in claim 2 or 3, c h a r ¬ a c t e r i s e d in that the outer side of the pin (30) is provided with a thread (49) cut in a direction opposite the internal thread (46) of the tubular knife (34). 5. An apparatus as claimed in claim 2, 3 or 4, c h r¬ a c t e r i s e d in that the pin (30) is shaped with a conical transition portion (47) expanding away from the free end of the pin (30) and continuing into a cylin¬ drical portion (48) carrying the external thread (49). 6. An apparatus as claimed in claim 2, 3, 4 or 5, c h a r a c t e r i s e d in that a fixed knife (51) is provided outside the tubular rotatable knife (34), said fixed knife automatically cutting the ham (14) while the rectum (53) cut free is being pulled out towards the ventral side (13) of the animal.

Inventors: ANDERSEN BOERGE CHRISTIAN, LYSBO BETTINA, ANDERSEN, BOERGE, CHRISTIAN, LYSBO, BETTINA
Applicants: CHICKMATIC APS
Application year: 1992
Main classification: A22B5
IPC codes: A22B5, A22C21