Danish Patent No. 173.412 Bl (Slagteriernes Forskningsinstitut) describes an apparatus and a method for seizing and holding a middle of a carcass by the spinal column and moving it on a mainly linear conveyor in the lengthways direction of the spinal column past a stationary saw which carries out a cutting operation. During transport, the split surface of the spinal column is in contact with the mainly horizontal surfaces on the conveyor elements in the conveyor and the inner side of the spinal column is in contact with oblique surfaces on the elements. The spinal column is held pressed into the wedge- shaped openings, which the horizontal surfaces and the oblique surfaces form together.

The apparatus may, for example, be arranged to cut off the rib top from a middle.

Tests of such an apparatus have shown that the rib top is not cut off correctly when the middle is from a carcass, which has been split unevenly, i. e. where sawing of the spinal column has been performed slightly to one side of the spinal column's symmetrical plane.

However, correct sawing off of rib top is important, because otherwise either valuable meat will be lost or subsequent processing of the meat has to be performed in a demanding manual process.

The object of the present invention is to provide an improvement of the apparatus, which can compensate for uneven splitting.

This is achieved in the apparatus of the invention, which is characterised in that it has - a measurement system located upstream of the cutting device which system is designed to measure horizontal positions of the inner surface of the middle a pre- determined distance below the horizontal surfaces of the conveyor elements while the middle is being conveyed past the measurement system, - a calculation unit designed to convert measurement data from this system into control signals and - drive means arranged to adjust the positions of the cutting device as a function of the control signals in a plane perpendicular to the transport direction of the middle during transport of the middle past the device.

In measurement of horizontal positions of the inner side of the middle below the spinal column it has proved possible to detect by how much the spinal column has been overcut or undercut during splitting, i. e. by how much the spinal column lies too high or too low in the apparatus compared to the correct cutting position. By means of this information, the height of the cutting device can be automatically adjusted so that a correct cut can be made in the middle by means of the apparatus.

It is mainly the position of the side of the ribs and the transverse processes, which are measured.

Advantageous embodiments of the apparatus of the invention are given in Claims 2-6.

The invention also relates to a method for cutting middles wherein conveyor elements on a mainly linear conveyor seize and hold a middle by the spinal column and move it in the lengthways direction of the spinal column while being held with the split surface of the spinal column in contact with mainly horizontal surfaces on the conveyor elements and the inside of the spinal column in contact with oblique surfaces on the elements, and with the spinal column pressed into the wedge-shaped openings which the horizontal surfaces and the oblique surfaces form together, and wherein the middle is cut in mainly the lengthways direction of the spinal column during the transport of the middle past a cutting device.

The method according to the invention is characterised in that horizontal positions on the inner surface of the middle are measured a pre-determined distance below the horizontal surfaces of the conveyor elements while the middle is transported past a measurement system arranged upstream of the cutting device, that measurement data from this system are converted into control signals by means of a calculation unit and that the positions of the cutting device in a plane perpendicular to the transport direction of the middle is adjusted automatically as a function of the control signals during the transport of the middle past the device.

Advantageous embodiments of the method according to the invention are stated in Claims 9-10.

In this document, the term middle shall mean particularly a middle from a pig carcass.

The cutting device can for instance be arranged and adjusted to cut off the rib top, to cut the meat free of the spinal column, to cut through the ribs at the rib heads or to carry out other cutting work on the middle at the spinal column.

The invention is explained in greater detail in the following with reference to the drawings, in which -Fig. 1 shows part of an apparatus according to the invention for automatic cutting off of rib top on middles, seen in vertical section, - Fig. 2 shows a sensor shoe in the apparatus of Fig. 1, seen from above, and - Fig. 3 shows an example of the horizontal displacements of the spinal column in the apparatus in the case of uneven splitting.

The apparatus is of the design described in Danish Patent No. 173.412 B 1, but with additional means for compensating for uneven splitting of the carcass.

It comprises a long mounting beam 1, bearing on its underside an I-shaped rail 2, from which there hang a series of connecting blocks 3. These are mutually connected by means

of chain links 4, which form a circulating chain driven by gearwheels in both ends of beam 1.

Onto the connecting blocks 3 are mounted fixing pieces 5, which on the underside have a horizontal surface 6, on which the split side of the spinal column can rest and a projection 7 with an oblique surface 8, on which the curved side of the spinal column can rest. The angle between surface 6 and surface 8 can be 50 to 80°. On the fixing piece 5 is mounted a hook 9, which can pivot on a shaft 10 and thereby pin the spinal column 11 in the V- shaped opening formed by the two surfaces 6 and 8. The hook is pivoted by means of a peg 12 with a roller 13 which runs on the side of a rail 14 mounted on the underside of the mounting beam 1. In the situation with no fixation the rail 14 runs at a great distance from the I-rail 2, so that the hook tip lies over the horizontal surface 6. At the point on the mounting beam 1 where the spinal column has been positioned in the V-shaped opening, rail 14 is moved closer to the I-rail 2 so that roller 13, during the transport of fixing piece 5 along beam 1, is actuated to the right and the hook tip is impelled into the spinal column 11, thus fixing it to piece 5.

The connecting block 3, the fixing piece 5, the hook 9 and the peg 12 with roller 13 together comprise a conveyor element 15 for a section of the spinal column.

The means of the apparatus for compensating for uneven splitting comprises a measurement system, which continuously measures horizontal positions of the inner side 20 of the middle below the spinal column as the middle is moved past the system. This comprises a measuring shoe 21 with an oblique front edge 22 (Fig. 2). The shoe is mounted on an arm 23, which is held and swivels in a bracket 24 on the mounting beam 1.

In operation the shoe 21 is actuated in the direction of the inner side 20 of the middle a pre-determined distance below the horizontal surface 6 (e. g. 30 to 55 mm), as a piston rod 26 of a cylinder 25 presses on arm 23. The arm 23 has an extension 27 on the other side of its swivel axle. A metal plate 28 is mounted on the extension. An inductive sensor 29 on the bracket 24 is arranged to sense the position of plate 28. The sensor emits a signal related to the shoe's 21 horizontal position, i. e. the position of inner side 20. At the hip end the surface sensed is the surface of the transverse processes 30, while at the neck end of the middle it is the surface of ribs 31. For each centimetre the middle is moved by the

conveyor, measurement data are recorded from the inductive sensor 29 into a calculation unit, which by means of an algorithm converts them to control signals. These control an aggregate, which adjust the vertical position of a rib top saw, the saw blade of which is indicated by line 32. The saw is mounted downstream of the measurement system.

Also in the measurement system is a light relay or similar for measuring the length of the middle during transport past the relay.

The device functions as follows: A middle is moved into the apparatus and the spinal column is seized and held by the conveyor elements 15, which bring it to the area on the conveyor where the measurement system is mounted. In the starting position the arm 23 has a position to the right, so that shoe 21 protrudes slightly in front of the middle. When the front edge of the middle hits the oblique side 22 of the shoe, this is pressed to the left until the straight edge at the end of side 22 starts to slide over the inside of the middle. The cylinder 25 holds the shoe pressed against the inside of the middle and its positions are measured by means of the inductive sensor 29 as the middle is moved past. The measurements, together with the measurement of the length of the middle, are processed in the calculation unit, which is connected with the inductive sensor and the light relay, and thereby a series of control signal values are obtained, each corresponding to a defined position of the middle in the transport direction. For example, the position of the first rib can be determined by means of the length of the middle, so that when cutting opposite the ribs, a"fixed"height setting of the saw can be used based on all the measurements of the transverse processes and when cutting opposite the transverse processes, another, continuous height setting of the saw is used, calculated by means of the individual measurements of the transverse processes.

When the middle comes to the rib top saw mounted downstream of the measurement system, the aggregate adjust the calculated height of the saw for cutting opposite the ribs, and when sawing is subsequently carried out opposite the transverse processes, the aggregate adjust the height continuously, e. g. for each centimetre that the middle is conveyed, controlled by the control signal values. This compensates for uneven splitting

and a correct sawing of rib top is achieved. The conveyor includes a stroke setting system so there is concordance between the individual measurements and the height settings of the saw.

Fig. 3 illustrates three different outcomes of a splitting process. The spinal column in a middle is assumed to have a cross-section corresponding approximately to a semicircle, where the ends of the semicircle are joined by a straight line section. This line section lies against the horizontal surface 6 on the fixing piece, while the circular part is in contact with oblique surface 8. Semicircle 40 illustrates the case where the spinal column has been correctly split in the middle. There is no need for correction of the rib top saw, which is in 0-position. Semicircle 41 illustrates the case where the splitting has been uneven and too much has been taken from the spinal column part of the middle. This has the effect that circle 41 is lying to the left of circle 40. The degree of unevenness of the split is measured by sensing the inner side of the middle, represented by line 41a. The horizontal displacement 41b of semicircle 41 compared to circle 40 can be converted into a measurement of how much has been incorrectly cut from the spinal column, namely section 41c. The height of the rib top saw can now be adjusted so that no valuable meat is cut away.

Semicircle 42 illustrates the case where the splitting is uneven the other way, so there is too much spinal column on the middle. Circle 42 lies to the right of circle 40 and as before the horizontal displacement 42b is measured and it is calculated how much has been incorrectly cut off, namely the vertical section 42c. In this case the height of the rib top saw needs to be reduced so that the entire rib top is cut off.

Unevenness in splitting may vary along the lengthways direction of the middle.

Unevenness is normally greatest at the hip end and less at the neck end, but can vary in between. The apparatus described is able to compensate for this, as the position of the rib top saw is adjusted as a function of the measured unevenness.