PRODUCTS

The present invention relates to a plant for fluid jet cutting especially of food products, comprising a conveyor for products which are to be cut, a nozzle for a cutting fluid jet, and a drive means for translational moving of the nozzle on a stand transversely of the travelling direction of the conveyor.

Such a plant is disclosed in US 4,962,568. One drawback thereof is associated with the fluid jet arrangement(s). This comprises a rail, which extends transversely of the travelling direction of the conveyor in the form of a conveying belt, and on which runs a carriage fitted with a spray nozzle, said nozzle pro¬ jecting from a slot formed in a casing for the arrange¬ ment. The carriage is driven by means of a piston-and- cylinder assembly. Such a design causes considerable dirtying owing to the water bouncing back from the conveying belt and entraining particles from products which are being cut or have been cut earlier. This dirty water penetrates through the slot in the casing which thus must be dismounted for cleaning of the arrangement. Further, there is a risk of leakage from the piston cylinders, which may soil the food product.

Moreover, the prior art fluid jet arrangement is fairly complicated and difficult to control exactly.

The object of the invention is to eliminate or at least reduce the problems described above.

This object is achieved by means of a plant and an arrangement having the characteristic features of the claims.

By using magnets when moving the nozzle and com- pletely enclosing at least the components moving the nozzle, i.e. the belt and one of the magnets, it is only necessary to clean the outer magnet and the outside of

the tube, when required. Thus, the belt can be lubricated with agents that need not be approved for use together with e.g. food products. The drive means according to the invention is further easy to control, thereby allowing the nozzle to be moved to exactly predetermined positions on its tube.

The invention will now be described in more detail with reference to the accompanying drawings in which Fig. 1 is a schematic vertical section of the plant, and Fig. 2 is a schematic horizontal section of the plant.

Two tubes 3, 3' are arranged above an endless belt conveyor 1 for products 2 which are to be cut with a jet, said tubes being attached to a stand S at a distance from each other in the travelling direction of the conveyor 1 (arrow A in Fig. 2), transversely of this direction, and extending in parallel with each other and with the plane of the conveyor 1. The tubes 3, 3' have open ends but are interconnected on each side of the conveyor by means of casings 4, 4', one accommodating a rotary motor 5 and the other a deflecting roller 6. The motor 5 is reversible and drives, via a transmission (not shown), a belt 7 which runs in the tubes 3, 3' and round the deflecting roller 6. At least the tube 3 is made of stainless steel having good permeability to magnet field lines. In the tube 3 there is arranged a first permanent magnet 8 whose outer circumference is in close vicinity of the inner circumference of the tube 3 and which in some suitable manner, for example by means of screws, is fixedly connected to the belt 7, thereby forming together with the belt 7 an endless loop so as to move together with the belt as the motor 5 is operated.

A second, annular permanent magnet 9 is positioned on the outside of the tube 3 and closely surrounds the tube. At its ends, this second magnet 9 is provided with slide bearings 10. The magnets 8, 9 are magnetised so as to attract one another via the wall of the tube 3 such that moving of the magnet 8 in the tube 3 by means of the

driving combination of motor 5, belt 7 and deflecting rol¬ ler 6 causes forced moving of the magnet 9 on the tube 3.

A fluid jet nozzle 11 is attached to the second, outer magnet 9 so as to move together with this. As mentioned above, the motor 5 is reversible (arrow B) and is driven to move the magnet 8 in the tube 3 back and forth (arrow C), and to stop/reverse when the magnets 8, 9 are positioned at either end of the tube 3. At these ends, the casings 4, 4' accommodate range detectors 12 connected in a control system 13.

As will be apparent from that stated above and as il¬ lustrated in the drawings, the tubes 3, 3' and their con¬ nection by means of the casings 4, 4' are liquid-tight. Fluid, preferably water, is supplied as a lubricant via a conduit 14 to the gap between the second, outer magnet 9 and the tube 3, and pressurised cutting fluid, usually water, is supplied via a conduit 15 to the fluid jet nozzle 11. The nozzle 11 may contain a deflector valve 16 according to the applicants' Swedish patent application 9103505-5. The conduits 14, 15 can be made of flexible plastic or resilient steel tubes so as to with¬ stand frequent stroke movements performed by the outer magnet 9 and the nozzle 11 attached thereto.

Advantageously, the plant also comprises a control rod 17 fixed to the stand and extending in parallel with the tube 3, for moving the outer magnet 9 which is then fixedly connected to a sliding ring 18 mounted on the control rod 17.

The belt conveyor 1 is preferably arranged for a constant rate of motion.

A plurality of fluid jet arrangements of the type described above may be arranged at a distance from each other in the longitudinal direction of the conveyor to perform any desired cutting pattern on the product(s) 2, thereby increasing the capacity of the plant. The angle of inclination of the tubes 3, 3' and 17 with the belt 1 need not be right, as the one illustrated, but it may be

in the range of e.g. 45-90°, according to the speed/de¬ sired inclination of the conveyor 1 in the cutting plane through the product 2.

The plant is further provided with a device for determining quality/quantity parameters of the product which is to be cut with a jet, for example meat, said parameters controlling the water jet arrangement(s) to produce any desired cut in the product(s) 2 by means of a computer. Such a device may be of the type described in US 4,962,568. It comprises a video camera 19 positioned to perceive the product on the conveying belt 1, and a light source which is arranged to illuminate the food product with a light line, thereby producing a ghost line on the product. The video camera perceives this ghost line and transforms the information of the ghost line to electric signals representing the width, length and thickness dimensions of the product. The signals are processed in a computer 20 in accordance with a pre¬ determined programme, said computer controlling the motor 5 via a motor revolution counter for cutting motions of the nozzle 11 such that the product is cut to segments of any desired weight/volume/profile.

Alternatively or supplementing the above-mentioned ghost line analysis, the technique according to US 4,631,413 (for which the applicants have a licence) can be used to control the jet arrangements for such cutting of the product that segments of any desired profile are obtained. This technique is directed to fluorescence analysis of food products, such as fish and meat pro- ducts, for determining their content of fat, bone, cartilage and connective tissue, and may be used to cut away undesired/desired components from the product 2.

The above-mentioned video camera, light source and computer are included in the previously mentioned control system 13. A person having ordinary skill in the art is competent to arrange the computer and the control system for producing any desired cutting pattern in the product.