Device for boning a piece of meat

Abstract: The invention relates to a device for removing an elongated bone (18) from a piece of neat (16), comprising means for conveying the piece of meat in succession through: one or more processing stations (24, 26) where the meat is scraped away from the bone, at right angles to the lengthwise direction of the bone, until a certain part of the bone surface is exposed, apart from a narrow connection between the meat and the bone, while the meat removed is guided away from the bone; a processing station where the above-mentioned narrow connection is broken. In a first processing station (22) a separation may be made along the length of the bone (18) through the meat (16) up to the bone. Preferably a second and third processing station (24; 26) each comprise two first helical rollers (28, 30; 54, 56) with ribs with opposite pitch and rotating in opposite directions to each other, the helical rollers (28, 30; 54, 56) being disposed parallel to and on either side of the path of the bone (18).

Description: The present invention relates to a device for removing an elongated bone from a piece of meat, in particular for removing the thigh bone from a piece of poultry thigh meat, comprising: conveyor means for conveying the piece of meat along a path with the bone generally aligned with the conveying direction; a first processing station positioned along said path with means for forming a separation in the meat along the length of the bone through the meat up to the bone; a second processing station positioned along said path with means for scraping the meat away from the bone generally perpendicular to the lengthwise direction of the bone, until a part of the bone surface is exposed, except for a narrow connection between the meat and the bone, and a final processing station comprising a cutting device disposed along said path for severing the narrow connection. Such a device is known from US-A-4 644 608. During the slaughter of animals often pieces of meat containing a bone not wanted by a consumer are obtained, and the bone must therefore be removed. Apart from the possibility of removing the bone by hand using a knife or scraper or the like, various devices for mechanized removal of a bone from a piece of meat are known, which devices can be used for processing large numbers of pieces of meat which must be the same shape. Such a known device, for example, presses a piece of meat between two surfaces provided with a recess for the bone. The meat is in this way pressed away from the bone to a place lying outside the press surfaces, while the bone is left behind in the space formed by the recesses. In another known device, the meat is stripped from a bone by gripping one end of the bone and then pulling the bone in the lengthwise direction thereof through an opening in a wall, which opening has slightly larger dimensions than the largest transverse dimension of the bone. In the device disclosed in US-A-4 644 608 the meat by means of a conveyor is guided through a peeling-off device comprising two plates separated by a narrow slot and fixed at an angle to the direction of conveyance, the slot having a broader portion near the conveyor. The broadened portion of the slot provides a passage for the bone while the meat is fed to the peeling-off device, while the meat cannot pass the plates and is peeled off the bone thereby. The known devices have a number of disadvantages. During pressing out of the bone, pulling out of the bone or peeling off the meat from the bone, the meat is exposed at least locally to great forces, as a result of which at the places in question the meat can lose its fibrous structure and/or can be damaged, which results in a great loss of value of the meat. Besides, the devices described will not produce the desired result, namely separating meat and bone as fully as possible, if: the shape and dimensions of the bone deviate from the expected configurations; while the bone is being pressed out it can end up between the press surfaces and become splintered, causing a large part of the meat to become unusable; while the bone is being pulled out there is a great risk that the end of the bone will not be gripped, and mechanical removal of the bone fails; the bone is jointed badly, in other words, apart from the bone, parts of adjacent bones are present in the piece of meat, or a part of the bone is missing; in this case the above-mentioned disadvantages result again during the pressing out or pulling out of the bone, the cause of such disadvantages being the unforeseeable shape of the bone to be removed; the bone is of poor quality, in other words, it is brittle and can easily break; during pulling out of the bone in particular, the prevailing forces may cause a fracture in the bone to be removed, so that only a part of the bone is pulled out of the meat; the bone is broken; the disadvantages hereof have already been discussed above; or any combination of the above-mentioned cases occurs. The object of the invention is to eliminate the above-mentioned disadvantages by providing a device of the aforementioned kind which is characterized in that the second processing station comprises at least one pair of rollers provided with helical ribs, the rollers being disposed parallel to and on opposite sides of said path, the helically ribbed rollers being adapted for touching the bone in operation, the rollers and the conveyor means being driven such that the apparent axial speed of movement of the roller ribs differs from the speed of movement of the conveyor means. Advantageous embodiments of this device are described in claims 2 - 11. The point of departure in operating the device according to the invention for removing a bone from a piece of meat is the presence or providing of a separation in the lengthwise direction of the bone, reaching up to the bone. This separation can be present naturally between muscle tissue running in the lengthwise direction of the bone or, if this is not the case, can be provided intentionally. In the latter case preference is given to providing the separation at the side of the piece of meat where there is as little meat as possible on the bone. In this way, the separation can be carried out most easily and will damage the meat as little as possible. The meat is exposed to very small forces in the device, so that its fibre structure is retained as much as possible, and the risk of damage is very low. The device according to the invention is also suitable for processing pieces of meat of a great variety of elongated shapes and dimensions, while as regards complete and sole removal of the bone it is unimportant whether the bone is badly jointed car the bone is of poor quality, or the bone is broken. The invention is explained with reference to the drawing, in which an embodiment of the device according to the invention is shown. Fig. 1 shows a side view of a device according to the invention. Fig. 2 shows a top view of a second processing station of the device of Fig. 1. Fig. 3 shows a part of a first conveyor with carriers of the device of Fig. 1. Fig. 4 shows a schematic cross-section, viewed in the direction of conveyance, of a piece of meat situated in the second processing station at the line IV in Fig. 2. Fig. 5 shows a top view of a part of the second processing station of the device of Fig. 1. Fig. 6 shows a schematic cross-section, viewed in the direction of conveyance, of a piece of meat situated in the second processing station at the line VI in Fig. 5. In the figures the same reference numbers relate to the same parts. Fig. 1 shows a fixing element 2, to which the various parts of the device, including a first conveyor 4, are fixed by means of supporting elements, which may if necessary be provided with suitable bearings. This conveyor has a number of gear wheels 6, over which an endless chain 8 is stretched, which chain is provided in some places with carriers 10 and a supporting pin 12. In operation, the chain 8 is moved by driving one of the gear wheels 6 in the direction indicated by an arrow 14, and the carriers and the supporting pin thereby move alternately along the bottom part of the chain track and along the top part thereof. At the beginning of the top part of the chain track (see Fig. 3) a piece of meat 16 containing an elongated bone 18 is placed on the carriers 10. The piece of meat is positioned in such a way that the bone is aligned in the direction of movement 14 of the chain 8, and the piece of meat 16 is supported at the rear side by the supporting pin 12. In order to prevent the meat from coming into contact with the links of the chain 8 and the lubricants thereon, the top side of the chain runs in a groove of a plate 20. In operation, the first conveyor 4 takes the piece of meat 16 in succession through a first processing station 22, and a second processing station 24, 26. In the first processing station 22, a separation can be made along the length of the bone through the meat up to the bone, for example by means of a rotary knife cutting in the vertical direction. The layout of the second processing station 24,26 and the way in which it works will be described with reference to Figs. 1 to 6. Disposed above the path of the piece of meat 16 on the first conveyor 4 are two first rollers 28 and 30 which are provided with helical ribs of opposite pitch and rotate in opposite directions to each other. These helical rollers are placed after one another parallel to and on either side of the path of the bone, and are driven by means of a motor 32 via a gearbox extension 34. The helical rollers 28 and 30 rotate in the directions indicated by arrows 35 and 36 respectively in Fig. 4, in the method of which they touch the bone while it is passing, near a separation which is present. In the case of the direction of rotation and pitch of the helical rollers shown the helical roller rib moves in the opposite direction to that of the direction of conveyance 14, and the helical rollers 28 and 30 have a downward scraping action on the connection between the bone 18 and the meat 16, which action is directed in the two peripheral directions. It should be pointed out that the above-mentioned movement of the helicai roller rib in the opposite direction to that of the direction of conveyance is not essential for good functioning of the device according to the invention. The only important factor is a difference between the speed of the conveyor and that of the helical roller rib, whereas the direction of movement of the two elements can be either identical or opposite. Placing the helical rollers 28 and 30 after one another means that even in the case of relatively great variations as regards shape and dimensions of the bone to be removed a correct scraping action is obtained, in particular because a helical roller and a bone can maintain constant contact during passing, because the bone is not strongly fixed on the carriers, or is otherwise prevented from selecting a particular position. Various guides 40, 42, 44, 46 and 48 are fitted above the path followed by the piece of meat 16 on the first conveyor 4, for guiding the meat downwards, so that, on the one hand, the meat ends up under the helical rollers 28 and 30 and, on the other, the bone is held above the carriers 10. The layout of the part 26 of the second processing station and the way in which it works will be described with reference to Figs. 1, 5 and 6. The piece of meat, partially scraped away from the bone 18 in the part 24 of the second processing station, is transferred by means of the first conveyor 4 from the carriers 10 to a worm conveyor comprising two elongated helical rollers 50 and 52 which are disposed next to each other and are provided with ribs of opposite pitch, and which rotate in opposite directions to each other. The helical rollers 50 and 52 contain helical rollers 54 and 56 with a larger pitch and a larger diameter, disposed one after the other. The opening between the helical rollers 50 and 52 is such that a bone cannot pass through it. The two helical rollers 50 and 52 are provided at the beginning thereof with conical parts 58 and 60 which, as a result of their vertical position, ensure that the bone from a piece of meat fed in by the conveyor 4 ends up at the top side of the helical rollers 50 and 52 and the meat ends up at the bottom side, all this as illustrated in Fig. 6. Otherwise, it is not necessary to provide both conical parts 58 and 60 of the helical rollers 50 and 52 with a helical rib; only one of the two parts need be designed as a conical helical roller. Instead of in the manner described, the transfer of a piece of meat from the part 24 of the second processing station to the part 26 of the second processing station can also take place by means of conveyors not described in detail, in which case the conical parts 58 and 60 of the helical rollers 50 and 52 can be omitted. The engaged gear wheels 66 and 68 ensure that when one of the two shafts 62 or 64 is driven the helical rollers 50, 54 and 58 turn in a direction 70 opposite to the direction 72 of the helical rollers 52, 56 and 60, so that the bone 18 and the piece of meat 16 are moved along by the worm conveyor in the direction away from the part 24 of the second processing station. The helical rollers 54 and 56 have the same function as the helical rollers 28 and 30 in the second processing station : they scrape the meat 16 off the bone 18 in the two peripheral directions of the bone. For a certain flexibility as regards the shape and dimensions of a bone to be removed, the scraping helical rollers 28, 30, 54 and 56 have ribs of elastic material or ribs containing resilient scraper elements. After passing the second processing station only a narrow connection between the bone and the piece of meat remains. This connection is broken by conveying the meat via a rotary knife 74 which is disposed below the path of the bone and is driven via a shaft 76 by a motor 78.

Claims: Device for removing an elongated bone (18) from a piece of meat (16), in particular for removing the thigh bone from a piece of poultry thigh meat, comprising: conveyor means (4, 50, 52, 58, 60) for conveying the piece of meat (16) along a path with the bone (18) generally aligned with the conveying direction; a first processing station (22) positioned along said path with means for forming a separation in the meat (16) along the length of the bone (18) through the meat up to the bone; a second processing station (24, 26) positioned along said path with means for scraping the meat (16) away from the bone (18) generally perpendicular to the lengthwise direction of the bone, until a part of the bone surface is exposed, except for a narrow connection between the meat and the bone; and a final processing station comprising a cutting device (74) disposed along said path for severing the narrow connection, characterized in that the second processing station comprises at least one pair of rollers (28, 30; 54, 56) provided with helical ribs, the rollers being disposed parallel to and on opposite sides of said path, the helically ribbed rollers being adapted for touching the bone in operation, the rollers and the conveyor means being driven such that the apparent axial speed of movement of the roller ribs differs from the speed of movement of the conveyor means. Device according to Claim 1, characterized in that the second processing station (24, 26) comprises two pairs of helically ribbed rollers (28, 30; 54, 56). Device according to Claim 1 or 2, characterized in that each pair of helically ribbed rollers (28, 30; 54, 56) is provided with ribs with opposite pitch and in that individual rollers in each pair are rotatable in opposite directions to each other. Device according to any of Claims 1-3, characterized in that the apparent direction of axial movement of the helical roller ribs on rotation of a pair of rollers is opposite to the direction of conveyance of the conveyor means. Device according to any of Claims 1-4, characterized in that the direction of rotation of the helically ribbed rollers is such that a surface of the ribs thereof moves over the bone in the direction of the conveyor means. Device according to any of Claims 1-5, characterized in that the rollers of a pair of helically ribbed rollers are placed after one another, viewed in the direction of conveyance of the conveyor means. Device according to any of Claims 2-6, characterized in that the second processing station comprises a first (4) and a second (50, 52, 58, 60) conveyor means, the meat and bone being transfered from the first conveyor means to the second conveyor means, the bone ending up at the top side of the second conveyor means, and the meat at the bottom side thereof, and in that the cutting device of the final processing station comprises a cutter (74) which is disposed at the bottom side of the second conveyor means. Device according to Claim 7, characterized in that the second conveyor means is in the form of a worm conveyor comprising an elongated third pair of rollers (50, 52) disposed next to each other and provided with helical ribs with opposite pitch, and rotating in opposite directions to each other, said third pair of helically ribbed rollers being disposed parallel to each other and on opposite sides of said path, the second pair of helically ribbed rollers (54, 56) being integral with the third pair of rollers (50, 52), while each roller of the second pair of helically ribbed rollers has a greater diameter than each roller of the third pair of helically ribbed rollers. Device according to Claim 8, characterized in that at least one of the rollers of the third pair of helically ribbed rollers is provided at the beginning thereof with a conical fourth roller (58, 60) with a helical rib and a direction of rotation corresponding to the third helically ribbed roller in line with which it is situated, while the point of the fourth helically ribbed roller is directed opposite to the direction of conveyance and is disposed in such a way that the bone ends up at the top side of the worm conveyor and the meat ends up at the bottom side thereof. Device according to Claim 8 or 9, characterized in that the pitch of the helical rib of the second pair of rollers (54, 56) is greater than that of the third pair of rollers (50, 52). Device according to any of Claims 2-10, characterized in that the helical rib of the first or the second pair of rollers can be deformed by the forces exerted thereon by the bone.

Inventors: VAN DE EERDEN HENRICUS FRANCIS, VAN DEN NIEUWELAAR ADRIANUS JO, VAN DE EERDEN, HENRICUS FRANCISCUS JACOBUS MARIA, VAN DEN NIEUWELAAR, ADRIANUS JOSEPHES
Applicants: STORK PMT, STORK PMT B.V.
Application year: 1990
Main classification: A22C17
IPC codes: A22C17, A22C21