Drill for vent cutter, vent cutter, method for making a vent opening

Abstract

A drill for a vent cutter, wherein: the drill comprises a first outer end, comprising a plurality of teeth, each tooth comprises a thickness defined in radial direction of the drill; each tooth comprises a first narrowing where the thickness of the tooth reduces when seen in circumferential direction of the drill, wherein the first narrowing defines a leading tip of the tooth; wherein the leading tip is rounded.

Description

[0001]DRILL FOR VENT CUTTER, VENT CUTTER, METHOD FOR MAKING A VENT OPENING The present invention relates to the field of the processing of slaughtered animals such as poultry. The invention relates in particular making a vent opening in the slaughtered carcass, which can e.g. be used subsequently for eviscerating the slaughtered carcass. More particular, the invention relates to a drill, a vent cutter, a processing device, and a method for making a vent opening. Slaughtered animals are subjected to several processing steps to convert them to food products. One of the processing steps in the beginning is the evisceration, at which the animal is usually already dead, and may also be defeathered (e.g. in the case of poultry), deskinned, and / or beheaded. During the evisceration, the viscera pack with several organs is removed from the slaughtered carcass. To enable this, first an opening is made through which the viscera pack can be reached and removed. Said opening is also referred to as the vent opening, and can e.g. be made around the cloaca or vent, in particular by removing the cloaca or vent. The vent opening can e.g. be made with a drill which has several teeth. The drill is rotated to cut through tissue of the slaughtered carcass to make the vent opening. The inventors have found that conventional drills have several disadvantages. For example, the cut is not always satisfactory, e.g. at the belly skin side or at the spine-side. It is an object of the invention to overcome the disadvantages of the prior art, or at least provide an alternative to the prior art. It is in particular an object of the invention to improve the cut made with a drill of a vent cutter. This object is achieved with a drill for a vent cutter (e.g. for making a vent opening in a slaughtered carcass), wherein: • the drill comprises a first outer end, comprising a plurality of teeth, • each tooth comprises a thickness defined in radial direction of the drill; • each tooth comprises a first narrowing where the thickness of the tooth reduces when seen in circumferential direction of the drill, wherein the first narrowing defines a leading tip of the tooth, • wherein optionally the leading tip is rounded. The invention thus relates, in embodiments, to a drill for a vent cutter. The vent cutter can be used to make a vent opening in a slaughtered carcass. The carcass can e.g. be the carcass of a poultry, e.g. a chicken, duck, or turkey. The vent opening can e.g. be used for removing the viscera pack through. The vent opening can e.g. be arranged in the area where the carcass had a cloaca or vent. Making or cutting the vent opening can e.g. include removing the cloaca or vent. Optionally, the carcass is already subjected to one or more processing steps priorly, e.g. being killed (e.g. stunned), defeathered, deskinned, and / or beheaded. Within this context, the term carcass can thus refer to a complete carcass or a carcass part. While the vent opening is being made, the carcass part can e.g. be hanging upside down, e.g. being suspended by its legs. The carcass can e.g. be hung in a shackles of an overhead conveyor. A plurality of teeth are arranged at a first outer end of the drill. The plurality of teeth can e.g. include at least two teeth, but preferably e.g. at least three, e.g. at least four, e.g. at least six. The teeth can e.g. be arranged equidistantly when seen in circumferential direction, e.g. with a gap between two subsequent teeth. The teeth may e.g. be identical to each other. The teeth may be configured to engage the carcass, e.g. around the cloaca or vent. The teeth may be configured to cut the cloaca or vent loose. The drill may e.g. be configured to rotate around a longitudinal axis to move the teeth, and exert a clamping and / or cutting force of the carcass. Optionally, the drill is hollow radially inward of the teeth. The first outer end is one of the outer ends of the drill when seen in longitudinal direction of the drill. If the carcass is arranged upside down when the vent is cut, the first outer end may e.g. be the bottom end. Within this text, the direction “longitudinal direction”, “radial direction”, and “circumferential direction” are being used, which relate to the respective directions of the drill (which may have a substantially cylindrical shape), unless explicitly mentioned otherwise. The longitudinal direction is parallel to a longitudinal centre axis of the drill. The radial direction is parallel to a radius of the drill, and thus perpendicular to the longitudinal direction. The circumferential direction is parallel to a circumference of the drill. Each tooth of the plurality of teeth has a thickness, which is how far the tooth extends in radial direction. The thickness is not constant or uniform over the entire tooth. There is a first narrowing when seen in circumferential direction, which defines a leading tip. Thus, in the first narrowing, the further in the circumferential direction, the smaller the thickness of the tooth is (and consequently the further in the opposite circumferential direction, the larger the thickness of the tooth is). The leading tip is configured to be the leading part of the tooth when the drill is rotating around its longitudinal axis. In the first narrowing, the thickness of the tooth reduces when seen in circumferential direction (in particular the direction in which the drill is configured to be rotated). The first narrowing may e.g. be a beveled section. At least a longitudinal outer end of the tooth comprises the first narrowing in circumferential direction. Optionally, the first narrowing extends over more than the longitudinal outer end, e.g. over the entire tooth. Optionally, the leading tip is rounded. Thus, the leading tip is not sharp. Instead, the leading tip is blunt. The inventors have found that this is beneficial to improve the process of making the vent opening. To make the vent opening, the cloaca or vent is cut loose by cutting through the belly skin on the one side and the connection between the intestine and the spine on the other side. When the drill is rotating around its longitudinal axis, the leading tip will engage the tissue of the carcass part and subject the tissue to forces. The teeth (and leading tips) will for example engage the belly skin. When using a rounded leading tip, the drill is able to build up more tension at the belly skin compared to a sharp tip, because it does not cut through the belly skin so quickly. After having built up more tension, the drill with rounded leading tip is able to cut the belly skin better and more completely. In addition, this allows to penetrate deeper into the carcass with the (teeth of the) drill. Indeed, since the leading tip is not sharp, there is less risk of damaging the intestines. The connection between the intestines and the spine can therefore be better cut. Being rounded entails that the outer surface of the leading tip is not defined by two straight lines intersecting each other. The outer surface of the leading tip is defined at least partially by a curved line, wherein the curve extends from a radial outer surface of the leading tip to a radial inner surface of the leading tip. The curve can be defined by one or more radii. Another way of saying that the leading tip is rounded can e.g. be that the outer surface of the leading tip (e.g. when seen in radial and / or circumferential direction) is a curved surface. Optionally, a main radial inner surface and a main radial outer surface of each tooth are curved and parallel to each other. Optionally, the main radial inner surface extends over the entire width of the tooth when seen in circumferential direction, e.g. with a constant radius of curvature. Optionally, the main radial outer surface extends until the first narrowing when seen in circumferential direction, e.g. with a constant radius of curvature. The first narrowing extends partially radially inwards having a radial outer surface that extends towards the main radial inner surface. Optionally, the teeth are arranged helical on the drill. Thus, a longitudinal axis of the drill and the longitudinal axes of the individual teeth are skew lines to each other. The longitudinal axes of each individual tooth may e.g. extend at an angle of 30-60 degrees to the longitudinal axis of the drill, e.g.40-50 degrees, e.g.45 degrees. Optionally, each tooth is non-symmetric. For example, due to the first narrowing being only on the leading side of the tooth, no symmetry axis for an individual tooth can be defined. Optionally, the drill is symmetric around its longitudinal axis, e.g. when the plurality of teeth is an even number. In embodiments, the leading tip being rounded is defined by a radius of curvature, wherein the radius of curvature is e.g. at least 1mm, e.g. between 1-7mm, e.g. between 2-5 mm, , e.g. between 2-4 mm, e.g. about 3 mm Having a radius of curvature implies that the rounded leading tip has the shape of a partial circle (e.g. when seen in a cross section). The radius of curvature can (e.g. as an imaginary line) be drawn parallel or tangent to the circumferential direction. The larger the radius of curvature, the less sharp (or more blunt) the leading tip is, which is advantageous for effects explained above. However, when the leading tip it too blunt, it will not be able to perform the cutting required to cut the tissue around the cloaca or vent loose. The above mentioned ranges have been found to satisfy both requirements. In embodiments, the leading tip being rounded is defined by a radius of curvature, wherein the radius of curvature is e.g. at least 10% of a length of the first narrowing when seen in the circumferential direction. For example, the length of the first narrowing can be defined starting from the location where the thickness of the tooth reduces until the end of the tooth in circumferential direction. Having a radius of curvature implies that the rounded leading tip has the shape of a partial circle (e.g. when seen in a cross section). The radius of curvature can (e.g. as an imaginary line) be drawn parallel or tangent to the circumferential direction. The radius of curvature can e.g. be at least 20 % of the length of the first narrowing, e.g. at least 50%, e.g. at least 75%, e.g. at least 100 %. In embodiments, a gap in circumferential direction is present between two subsequent teeth, wherein said gap is smaller than 4 mm, e.g. smaller than 3 mm, e.g. between 2-3 mm, e.g. between 2 or 2.2 – 2.7 mm, e.g. between 2 or 2.4-2.6 mm, e.g. about 2.5 mm. It is noted that these gaps are smaller than the gaps in conventional drills. The inventors have found that reducing the size of the gaps is advantageous. It is less likely that (part of) the intestines get stuck in the gap, which can reduce the unwanted damage to the intestines. In embodiments, the plurality of teeth is three teeth or four teeth. It has been found that these embodiments on the one hand are able to exert enough forces / pressure on the tissue of the carcass to efficiently make the vent opening, while on the other hand limit the number of gaps, which again makes it less likely that (part of) the intestines get stuck in the gap. It may in particular be advantageous to combine these embodiments with the possible sizes for the gap as explained above. In embodiments, an end section (in longitudinal direction) of the tooth has a second narrowing where thickness of the tooth reduces when seen in longitudinal direction of the drill, wherein optionally the leading tip is defined by the overlap between the first narrowing and the second narrowing. The second narrowing may e.g. be a bevelled section. In the second narrowing, the thickness reduces further in the longitudinal direction. Thus, the outer end of the tooth is thinner. Optionally, second narrowing entails that the tooth has an end (e.g. configured to engage the carcass) that can be classified as an end line rather than an end surface, e.g. being sharp rather than rounded. The leading tip being defined by the overlap between the first and second narrowing, entails that thickness of the leading tip reduces in two direction. Optionally, the reduction in thickness in the circumferential direction due to the first narrowing is smaller (e.g. thereby allowing being rounded) than the reduction in thickness in the longitudinal direction due to the second narrowing. In embodiments, in a cross section of each tooth taken in radial direction, a (main) radial inner border and a (main) radial outer border are parallel to each other, wherein the radial outer border is smaller than the radial inner border (in length when seen in circumferential direction), wherein the radial outer border e.g. has a length of at least 70% of the length of the radial inner border, e.g. at least 80%, e.g. at least 90%. The (main) radial outer border is smaller than the (main) radial inner border because of first narrowing, wherein the thickness reduces from the (main) radial outer border towards the (main) radial inner border. However, because the leading tip is rounded instead of sharp, the first narrowing can be smaller, and the radial outer border thus remains larger. This increases the structural stability of the tooth, and reduces the likelihood of the leading tip breaking off. In embodiments, the first narrowing extends over less than 30% of the tooth when seen in circumferential direction, e.g. less than 20%, e.g. less than 10%. Because the leading tip is rounded instead of sharp, the first narrowing can be smaller. This increases the structural stability of the tooth, and reduces the likelihood of the leading tip breaking off. In embodiments, the invention relates to a vent cutter. The vent cutter may e.g. comprise a drill according to any of the embodiments described herein, e.g. for making a vent opening in a slaughtered carcass. Optionally, the vent cutter comprises a drill position drive mechanism configured to move the drill from a carcass receiving position to a drilling position. For example, in the carcass receiving position the drill may be retracted, for allowing the carcass to be positioned (e.g. in a support mechanism) without contact between the drill and the carcass. For example, in the drilling position the drill (e.g. at least the teeth) is configured to engage the carcass part. For example, the teeth may be configured to engage the belly skin and / or skin / tissue around the cloaca. For example, the teeth may be arranged (partially) into the carcass. The movement from the receiving position to the drilling position can e.g. be a vertical movement, e.g. downwards. The movement from the receiving position to the drilling position can e.g. be a movement in a longitudinal direction of the drill. Optionally, the drill position drive mechanism is configured to gradually move the drill further in the longitudinal direction during the drilling (e.g. while the drill is rotating around its longitudinal axis). In that case, the drilling position may e.g. be the position where the drilling movement is started. The drill position drive mechanism may e.g. comprise a follower wheel configured to follow a guide track or cam track. The follower wheel can be connected to the drill, e.g. via one or more levers or connectors. The guide track or cam track is configured to cause the follower wheel to move (e.g. in vertical direction), which causes the drill to move. Optionally, the vent cutter comprises a drill rotation drive mechanism configured to rotate the drill around a longitudinal axis of the drill. Said rotation causes the drilling movement, during which the tissue around the cloaca or vent is cut. First the tension of the belly skin can be increased with the rounded leading tips by the rotation of the drill. Then, the belly skin can be cut by the rotation of the drill on the one side, and the tissue between the intestines and the spine can be cut by the rotation of the drill on the other side. The drill rotation drive mechanism may e.g. comprise a follower wheel configured to follow a guide track or cam track. The follower wheel can be connected to the drill, e.g. via one or more levers or connectors. The guide track or cam track is configured to cause the follower wheel to move, which causes the drill to move. The follower wheel can e.g. be a gear with teeth which intermesh with teeth on the guide track, such that the follower wheel is rotated and causes the drill to rotate. In embodiments, the drill position drive mechanism is configured to move the drill to a predetermined drilling position, wherein the drill position drive mechanism comprises a position adapting element for selecting a drilling position between a plurality of predetermined drilling positions, e.g. two or more drilling positions, wherein the drill is arranged at mutually different depths into the slaughtered carcass. Optionally, the position adapting element is also configured to adapt the position of a centering pin and / or a clamping element. When the drill is being moved deeper into the carcass during the drilling movement the drilling position may e.g. be the position where the drilling movement is started, such that e.g. on a given position of the carcass part in the processing line the depth at which the drill is arranged is mutually different depending on the selected drilling position. These embodiments allow to adapt the vent cutter to the size of the carcass, which may for example vary depending on which type of poultry (e.g. which breed of chicken) is being processed. Usually a badge of carcasses of similar size are being processed, which allows to adjust the position adapting element once for such badge. For example, when the drill position drive mechanism comprises a follower wheel and guide / cam track, the position adapting element may be configured to adapt the guide / cam track. For example, the position adapting element may comprise a plate which forms the (e.g. upper) border of the track for a portion thereof. The follower wheel is biased against said border, e.g. by means of a resilient member such as a spring. The position adapting element may further comprise an actuator configured to move the plate. Optionally, the vent cutter further comprises a control unit configured to receive or determine a carcass size parameter, and configured to control the drill position adapting element base on the carcass size parameter. The control unit may e.g. be configured to receive data from a carcass measurement station, e.g. upstream of the vent cutter. In embodiments, the vent cutter comprises a positioning pin configured to be arranged into the slaughtered carcass, and a pin drive mechanism configured to move the positioning pin relative to the drill. For example, the positioning pin can be configured to be arranged (partially) into the cloaca or vent. Optionally, the positioning pin comprises a widened portion. Optionally, the positioning pin is arranged coaxial with the drill. Optionally, the positioning pin has a diameter smaller than the drill. The pin drive mechanism may e.g. be configured to move the positioning pin in a longitudinal direction. The pin drive mechanism may e.g. comprise a follower wheel configured to follow a guide track or cam track. The follower wheel can be connected to the positioning pin, e.g. via one or more levers or connectors. The guide track or cam track is configured to cause the follower wheel to move (e.g. in vertical direction), which causes the positioning pin to move. In embodiments, the vent cutter further comprises a clamp for clamping the skin around the cloaca or vent. The clamp can e.g. by a cylindrical bushing coaxial to the drill and the positioning pin, e.g. having a diameter larger than the positioning pin but smaller than the drill. The clamp can e.g. be configured to clamp the skin between the (radial) inside of clamp and the positioning pin, e.g. the widened portion of the positioning pin. A clamp drive mechanism may e.g. be configured to move the clamp in a longitudinal direction. The clamp drive mechanism may e.g. comprise a follower wheel configured to follow a guide track or cam track. The follower wheel can be connected to the clamp, e.g. via one or more levers or connectors. The guide track or cam track is configured to cause the follower wheel to move (e.g. in vertical direction), which causes the clamp to move. Optionally, the pin drive mechanism is configured to move the positioning pin relative to the drill and / or the clamp. Optionally, the clamp drive mechanism is configured to move the clamp relative to the drill and / or the positioning pin. Optionally, the drill position drive mechanism is configured to move the drill relative to the positioning pin and / or the clamp. In embodiments, the vent cutter comprises a support bracket for supporting the carcass part. In embodiments, the vent cutter comprises a hip support configured to support hips of the carcass part. Optionally, the vent cutter comprises a hip support drive mechanism configured to move the hip support for moving the hips. This may make the cloaca more accessible for the drill. In embodiments, the vent cutter further comprises a back support for supporting the back of the slaughtered carcass, and a back support drive mechanism configured to move the back support between a retracted position to allow positioning the carcass on a support bracket without engaging the back support, and a support position wherein the back support engages a back of the slaughtered carcass. Being able to arrange the back support in the retracted position advantageously allows better positioning of the carcass into the vent cutter, while during the operation of the drill the carcass part is supported and held in position by the back support. The back support can e.g. be plate configured to engage the back of the carcass part. The back support drive mechanism can be follower wheel and guide / cam track, e.g. with one or more lever. Optionally, the back support drive mechanism is configured to move the back support relative to the support bracket and / or a hip support. This allows to support and position the back more accurately, and thus position the drill more accurately. Optionally, the back support drive mechanism is configured to move the back support partially or completely in a direction perpendicular to the longitudinal axis of the drill. For example, the back support drive mechanism may be configured to move the back support is a direction radially outward / inward of a drum of a carousel. For example, the back support drive mechanism may be configured to move the back support partially or completely in a horizontal direction. In embodiments, the vent cutter is configured make a vent opening in the carcass by removing the cloaca or vent. The drill is configured to cut the cloaca or vent loose. For example, the drill (in particular the teeth) is configured to cut through the belly skin and / or through tissue connecting the intestines to the spine The invention further relates to a processing device for making a vent opening in a slaughtered carcass, comprising a plurality of vent cutters according to any of the embodiments described herein, wherein optionally the processing device is a carousel device comprising the vent cutters at the periphery thereof, and configured to move the vent cutters in a closed loop trajectory, e.g. being circular. The carousel device may e.g. comprise a stationary element having a plurality of guide tracks for the various drive mechanisms. The vent cutter may e.g. be connected to a rotatable drum. The processing device may further comprise a conveyor for moving the carcass parts, e.g. an overhead conveyor with a plurality of shackles configured to hold the carcass parts by the feet or legs. The invention further relates to a method for making a vent opening. Although the method can be performed with the drill or vent cutter according to the invention; neither the drill / vent cutter, nor the method is limited thereto. Features explained herein with reference to the drill / vent cutter have the same meaning with respect to the method unless explicitly defined otherwise. Features explained with reference to the drill / vent cutter can be applied mutatis mutandis to the method to achieve the similar advantages, and vice versa. One or more objects of the invention can be achieved with a method for making a vent opening in a slaughtered carcass, comprising a step of using a drill or vent cutter according to any of the embodiments described herein to make the vent opening in the slaughtered carcass. One or more objects of the invention can be achieved with a method for making a vent opening in a slaughtered carcass, comprising the following steps: • moving drill from a carcass receiving position to a drilling position, wherein the drill comprises a plurality of teeth, wherein in the drilling position the teeth engage the skin around the cloaca, including belly skin; • rotating the drill, thereby increasing the tension in the belly skin with the teeth without cutting it; • while rotating the drill, cutting connections between the large intestine and the spine; • cutting the belly skin to cut the cloaca loose. Optionally, the teeth have a leading tip which is rounded. Optionally, the drill is according to any of the embodiments described herein, e.g. being part of a vent cutter according to any of the embodiments described herein. Exemplary embodiments of the invention are described using the figures. It is to be understood that these figures merely serve as example of how the invention can be implemented and are in no way intended to be construed as limiting for the scope of the invention and the claims. Like features are indicated by like reference numerals along the figures. In the figures: Fig 1A: schematically illustrates a vent cutter with a drill in a carcass receiving position; Fig 1B: schematically illustrates the vent cutter with the drill being moved towards a drilling position; Fig. 1C: schematically illustrates the drill; Fig. 1D: schematically illustrates a closer view of the teeth of the drill; Fig. 1E: schematically illustrates a cross-section of a tooth; Fig. 2A: schematically illustrates a carousel processing device comprising a plurality of vent cutters, of which one is shown; Fig. 2B: schematically illustrates a position adapting element in a first position; Fig. 2C: schematically illustrates the position adapting element in a second position; Fig. 2D: schematically illustrates an actuator of the position adapting element; Fig.3: schematically illustrate a cross section of a vent cutter having a moveable back support. Fig. 1A-1B schematically illustrate a vent cutter 1; wherein Fig 1A schematically illustrates the vent cutter 1 with drill 10 in a carcass receiving position; Fig 1B schematically illustrates the vent cutter 1 with the drill 10 being moved towards a drilling position. The vent cutter 1 can be used to make a vent opening in a carcass (part) of a slaughtered animal. In the shown embodiment, the vent cutter 1 is configured to make the vent opening in a poultry carcass part, in particular a chicken. However, the principles explained herein can be applied to other animals as well. The carcass part can be supported in a shackle of an overhead conveyor, which moves the carcass part towards the vent cutter 1. The shackle supports the carcass part by the legs or feet, such that the carcass part is having upside down. The vent cutter 1 comprises a support bracket 40 configured to be arranged between the legs of the carcass part. The legs of the carcass part are opened as they are moved over the support bracket 40, thereby making the cloaca or vent more accessible. The vent cutter 1 further comprises a hip support 50 configured to engage the hips of the carcass part from below. The hip support 50 can be moved upwards for making the cloaca or vent more accessible. The vent cutter 1 further comprises a positioning pin 20, a clamp 30, and the drill 10. The drill 10, positing pin 20, and clamp 30 are coaxial as they have a common longitudinal axis L. Furthermore, the drill 10, positing pin 20, and clamp 30 can each independently of each other be moved in a longitudinal direction. The longitudinal direction is a direction parallel to the longitudinal axis L. The longitudinal direction, as well as a radial direction and a circumferential direction when mentioned herein, and are defined as said respective directions of the drill 10, unless explicitly mentioned otherwise. After the carcass part is supported by the various support, the position of the carcass part is well-defined as well. The positioning pin 20 is then moved downwards into the longitudinal direction L from a carcass receiving position to a drilling position. In fig. 1A and fig. 1B, the positioning pin 20 in the drilling position, which is into the cloaca of the carcass part. The positioning pin 20 comprises a widened portion 21 which opens the cloaca. Then, the clamp 30 is moved downwards in the longitudinal direction L from a carcass receiving position to a drilling position. In fig.1A the clamp 30 is in the carcass receiving position and in fig. 1B in the drilling position. The clamp 30 is a cylindrical bushing 30 with an inner diameter that is larger than the outer diameter of the widened portion 21 of the positioning pin 20. The clamp 30 is positioned over the widened portion 21, such that the tissue around the cloaca is clamped between the clamp 30 and the widened portion 21. Then, the drill 10 is moved downwards into the longitudinal direction L from a carcass receiving position (shown in fig. 1A) to a drilling position. The inner diameter of the drill 10 is larger than the outer diameter of the clamp 30. The drill 10 has a plurality of teeth 11, which engage tissue around the cloaca. The drill 10 is furthermore rotated around its longitudinal axis L. During this rotation, the tissue around the cloaca or vent is eventually cut loose. Fig. 1C schematically illustrates a closer view of an embodiment of a drill 10; and Fig. 1D schematically illustrates a closer view of an embodiment of the teeth 11 of the drill 10. The plurality of teeth 11 can e.g. include three, four, five, or six teeth 11. Each tooth 11 is embodied the same, and the teeth 11 are arranged equidistantly over the circumference of the drill 10. Thus, a gap 131 between each two subsequent teeth 11 is equal. Each tooth 11 has a thickness 122. The thickness 122 is how far the tooth 11 extends in radial direction. The thickness 122 is not constant over the entire tooth 11. In particular, the tooth 11 comprises a first narrowing 112. The first narrowing 112 is a beveled section, where the thickness 122 of the tooth reduces when seen in circumferential direction. Thus, in the shown example, the further in the counterclockwise direction, the smaller the thickness of the tooth 11 is in the first narrowing 112. Since, the drill 11 is configured to be rotated in the counterclockwise direction, the first narrowing 112 will be the leading part of the tooth 11 during rotation. Furthermore, it can be seen that the teeth 11 are arranged helical. A longitudinal axis 15 of the tooth 11 extends non-parallel (in particular at an angle of 45 degrees) to the longitudinal axis L of the drill 10, which implies that the longitudinal outer end of the first narrowing 112 is the most leading part during rotation, thereby defining a leading tip 114. Although in the shown embodiment the first narrowing 112 extends over practically the entire longitudinal length of the tooth 11, it is also possible that the first narrowing only is provided at the leading tip 114. The figures further illustrate that the leading tip 114 is rounded rather than sharp. The rounded leading tips 114 will, during rotation, engage the belly skin of the carcass part. Rather than cutting through it almost immediately, the tension in the belly skin will be increased first. This is advantageous as it allows to cut the belly skin more completely. At the same time, the rounded leading tips 114 are less likely to damage the intestine of the carcass part. This allows to move the teeth 11 further into the carcass part, and better break the connections between the intestine and the spine. Thus, the cloaca or vent can be cut loose more efficiently both on the breast-side (belly skin) and back-side (connections between intestine and spine). In particular, a radius 123 can be defined, and (a part of) an outer surface of the leading tip 114 is formed by a curve defined by said radius 123. The radius 123 can e.g. be between 2-4 mm, e.g. being about 3 mm. The teeth 11 furthermore comprise a second narrowing 113. The second narrowing 113 is a beveled section, where the thickness 122 of the tooth 11 reduces when seen in longitudinal direction L. The further to the longitudinal outer end 111 of the tooth 11, the smaller the thickness of the tooth 11. The first narrowing 112 and the second narrowing 113 have a region where they overlap. This region can e.g. be considered to correspond to the leading tip 114. The second narrowing 113 is, unlike the first narrowing 112, not rounded in the shown example. Fig.1E schematically illustrates a cross-section of a tooth 11. A radial inner surface 116 is indicated, as well as a main radial outer surface 115. On the leading side, the first narrowing 112 extends radially inward from the main radial outer surface 115 towards the radial inner surface 116. The rounding 112a of the first narrowing 112 is also visible. A trailing surface 117 extends between the radial inner surface 116 and the main radial outer surface 115 on the trailing part of the tooth 11. The thickness 122 is defined between the radial inner surface 116 and the main radial outers surface 115. The radial inner surface 116 and the main radial outer surface 115 are parallel to each other. Both are curved, with a radius of curvature which extends perpendicular to the longitudinal axis L of the drill 10. The main radial outer surface 115 is smaller in length (when seen in circumferential direction) than the radial inner surface 116, but is still at least 80% of the length of the radial inner surface 116. This is relatively long, while the length 120 of the first narrowing 112 is relatively short. This improves the structural stability of the first narrowing 112, making it less likely for the first narrowing 112 or the leading tip 114 to break off. Indeed, the forces exerted onto the leading tip 114 by the carcass part are better divided and the internal stresses remain lower. Fig.1C and fig.1D illustrate the gap 131 in circumferential direction between two subsequent teeth 11. The gap is smaller than 3 mm, e.g. between 2-3 mm, e.g. about 2.5 mm. The inventors have been found that these sizes of gaps 131 provide advantages over larger gaps, since there is less space for the intestine to get between the teeth 11, and subsequently break. The inventors have also found that it may be advantageous when the drill 10 has exactly three teeth 11 or exactly four teeth 11. This reduces the number gaps 131 and thus the space for the intestine to get between the teeth 11, and subsequently break. At the same time, three or four teeth 11 are still able to provide sufficient(ly balanced) pressure / force to the tissue of the carcass part. Fig. 2A schematically illustrates a processing device 2. Only a single vent cutter 1 is shown for the sake of clarity, but it will be understood that in practice the processing device 2 comprises a plurality of vent cutters 1. The processing device 2 is a carousel device, having a stationary drum 60. The vent cutters 1 are rotated around the stationary drum 60. The carcass parts may be supported partially by the vent cutters 1, but are also held in a shackle (not shown) of an overhead conveyor. The shackles moves along with vent cutter 1 for a part of rotation around the drum 60, during which the vent opening is made in the carcass part. Different components of the vent cutter 1 are moved to position the carcass part and make the vent opening. For example, the drill 10, positioning pen, and clamp are moved in the longitudinal direction. The hip support 50 is moved to position the hips of the carcass part. The vent cutter 1 comprises various drive mechanisms for moving the respective components. The drive mechanism comprise a follower wheel (e.g. one follower wheel 63 is indicated) that follow guide / cam tracks in the drum 60. Two tracks 61, 62 are indicated in fig. 2A. The tracks 61, 62 extend around the drum 60, while also extending in vertical directions. This forces the follower wheel to follow in the vertical directions, which can be translated to the desired movement of the respective component, e.g. via one or more levers and / or hinges. The track indicated with reference numeral 61 is part of the drill position drive mechanism for moving the drill 10 from the carcass receiving position to the drilling position. A resilient member 71 such as a spring biases the follower wheel upwards, while the track 61 limits how far upwards the follower wheel can be. A position adapting element allows to adapt the depth of the drilling position. The position adapting element comprises a moveable plate 70 which can be moved between a first position (fig. 2A and fig. 2B) and a second position (fig. 2C). In the first position the plate 70 is arranged lower than in the second position, meaning that the drill 10 will be moved deeper into the carcass part. Fig. 2E illustrates an actuator 72 which is configured to control the position of the plate 70. Although not shown in the figures, the actuator 72 may optionally be controlled by a control unit. The position adapting element thus allows to adapt the depth the drill 10 is moved. The vent cutter 1 can as such be adapted to the carcasses to be processed. The size of the carcass may e.g. vary. Optionally, the control unit determines or receives a carcass size parameter, based on which the position adapting element is controlled. Fig. 3 schematically illustrates a cross section of the vent cutter 1. The vent cutter comprises a back support 80. The back support 80 is configured to engage the back of the carcass part. In addition, the back support 80 is moveable from a first position to a second position. In the first position the back support is retracted, such that the carcass part can be arranged on the support bracket 40 without contact between the back support 80 and the carcass part. Thereafter, the back support 80 is moved to what in fig. 3 is the right-hand side to engage and position the back of the carcass part. The positioning of the back affects the positioning of the cloaca, and hence the accuracy of the drilling with the drill 10. Advantageously, the shown embodiment allows to move the back support 80 independently of the hip support 50 and the support bracket 40. The decoupling of the various support elements 80, 50, 40 improves the accuracy of the positioning of the carcass part. A back support drive mechanism enables the independent movement of the back support 80. The back support drive mechanism comprises a follower wheel 81 which follows a guide / cam track, e.g. in a drum of a carousel. The track causes the follower wheel 81 to move in vertical direction, which via levers 82, 83, 84 and hinges 85, 86, 87 causes the back support 80 to move. As required, detailed embodiments of the present invention are described herein; however, it is to be understood that the disclosed embodiments are merely examples of the invention, which may be embodied in various ways. Therefore, specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching those skilled in the art to practice the present invention in various ways in virtually any suitable detailed structure. Not all of the objectives described need be achieved with particular embodiments. Furthermore, the terms and expressions used herein are not intended to limit the invention, but to provide an understandable description of the invention. The words “a”, “an”, or "one" used herein mean one or more than one, unless otherwise indicated. The terms "a multiple of", “a plurality” or "several" mean two or more than two. The words "comprise", "include", “contain” and "have" have an open meaning and do not exclude the presence of additional elements. Reference numerals in the claims should not be construed as limiting the invention. The mere fact that certain technical features are described in different dependent claims still allows the possibility that a combination of these technical measures can be used advantageously. A single processor or other unit can perform the functions of various components mentioned in the description and claims, e.g. of processing units or control units, or the functionality of a single processing unit or control unit described herein can in practice be distributed over multiple components, optionally physically separated of each other. Any communication between components can be wired or wireless by known methods. The actions performed by the control unit can be implemented as a program, for example computer program, software application, or the like. The program can be executed using computer readable instructions. The program may include a subroutine, a function, a procedure, an object method, an object implementation, an executable application, a source code, an object code, a shared library / dynamic load library and / or other set of instructions designed for execution on a computer system. A computer program or computer-readable instructions can be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied with or as part of other hardware, but can also be distributed in other forms, such as via internet or other wired or wireless telecommunication systems.

Claims

CLAIMS 1. A drill for a vent cutter, wherein: • the drill comprises a first outer end, comprising a plurality of teeth, • each tooth comprises a thickness defined in radial direction of the drill; • each tooth comprises a first narrowing where the thickness of the tooth reduces when seen in circumferential direction of the drill, wherein the first narrowing defines a leading tip of the tooth, • wherein the leading tip is rounded.

2. The drill according to claim 1, wherein the leading tip being rounded is defined by a radius of curvature, wherein the radius of curvature is e.g. at least between 2-4 mm, e.g. about 3 mm.

3. The drill according to any of the preceding claims, wherein a gap in circumferential direction is present between two subsequent teeth, wherein said gap is smaller than 3 mm, e.g. between 2-3 mm, e.g. about 2.5 mm.

4. The drill according to any of the preceding claims, wherein an end section of the tooth has a second narrowing where the thickness of the tooth reduces when seen in longitudinal direction of the drill, wherein the leading tip is defined by the overlap between the first and second narrowing.

5. The drill according to any of the preceding claims, wherein in a cross section of each tooth taken in radial direction, a radial inner border and a radial outer border are parallel to each other, wherein the radial outer border is smaller than the radial inner border, wherein the radial outer border has a length of at least 80% of the length of the radial inner border.

6. A vent cutter comprising • a drill according to any of the preceding claims; • a drill position drive mechanism configured to move the drill from a carcass receiving position to a drilling position • a drill rotation drive mechanism configured to rotate the drill around a longitudinal axis of the drill.

7. The vent cutter according to the preceding claim, wherein the drill position drive mechanism is configured to move the drill to a predetermined drilling position, wherein the drill position drive mechanism comprises a position adapting element for selecting a drilling position between a plurality of predetermined drilling positions, e.g. two drilling positions, wherein the drill is arranged at mutually different depths into the slaughtered carcass, wherein optionally the vent cutter further comprises a control unit configured to receive or determine a carcass size parameter, and configured to control the drill position adapting element base on the carcass size parameter.

8. The vent cutter according to any of the preceding claims, further comprising a positioning pin configured to be arranged into the slaughtered carcass, and a pin drive mechanism configured to move the positioning pin relative to the drill.

9. The vent cutter according to any of the preceding claims, further comprising a clamp for clamping the skin around the cloaca.

10. The vent cutter according to any of the preceding claims, further comprising a back support for supporting the back of the slaughtered carcass, and a back support drive mechanism configured to move the back support between a retracted position to allow positioning the carcass on a support bracket without engaging the back support, and a support position wherein the back support engages a back of the slaughtered carcass.

11. The vent cutter according to the preceding claim, wherein the back support drive mechanism is configured to move the back support relative to the support bracket and / or a hip support.

12. The vent cutter according to any of the preceding claims, further configured to make a vent opening in the carcass by removing the cloaca.

13. A processing device for making a vent opening a slaughtered carcass, comprising a plurality of vent cutters according to any of the preceding claims, wherein the processing device is a carousel device comprising the vent cutters at the periphery thereof, and configured to move the vent cutters in a closed loop trajectory, e.g. being circular.

14. A method for making a vent opening in a slaughtered carcass, comprising a step of using a drill or vent cutter according to any of the preceding claims to make the vent opening in the slaughtered carcass.

15. A method for making a vent opening in a slaughtered carcass, comprising the following steps: • moving drill from a carcass receiving position to a drilling position, wherein the drill comprises a plurality of teeth, wherein in the drilling position the teeth engage the skin around the cloaca, including belly skin; • rotating the drill, thereby increasing the tension in the belly skin with the teeth without cutting it; • while rotating the drill, cutting connections between the large intestine and the spine; • cutting the belly skin to cut the cloaca loose.

16. The method according to claim 15, wherein the teeth have a leading tip which is rounded.

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