A CUTTING DEVICE ADAPTED TO BE PLACED ABOVE A GAP EXTENDING ACROSS A CARRYING SURFACE OF A CONVEYOR SYSTEM

Abstract

A cutting device adapted to be placed above a gap extending across a carrying surface of a conveyor system with the cutting plane of the cutting device extending through the gap. The cutting device cuts food items into smaller food items via rotational movement of the cutting device while the food items conveyed by the conveyor system pass the gap. The cutting device includes an arm and a cutting blade mounted to one end of the arm. The opposite end of the arm is adapted to be mounted to a driving unit for supplying rotational movement of the arm and thus the cutting blade. A cutting edge side of the cutting blade engages with the food item under an angle such that the cutting blade exerts with a downwardly facing force onto the food item and towards the carrying surface of the conveyor system during the cutting.

Claims

1-15. (canceled)

16. A cutting device adapted to be placed above a gap extending across a carrying surface of a conveyor system with the cutting plane of the cutting device extending through the gap, where the cutting device is adapted for cutting food items into smaller food items via rotational movement of the cutting device while the food items conveyed by the conveyor system pass the gap, the cutting device comprising: an arm, a cutting blade mounted to one end of the arm, the opposite end of the arm being adapted to be mounted to a driving unit for supplying rotational movement of the arm and thus the cutting blade; wherein the cutting blade is mounted to the arm such that, while cutting a food item into smaller food items, a cutting edge side of the cutting blade engages with the food item under an angle such that the cutting blade exerts with a downwardly facing force onto the food item and towards the carrying surface of the conveyor system during the cutting.

17. The cutting device according to claim 16, wherein the cutting edge side and the carrying surface or a tangent at the point of contact of the carrying surface around the gap form an acute angle during the cutting.

18. The cutting device according to claim 17, wherein the acute angle is between 10° and 60°.

19. The cutting device according to claim 16, wherein the angle is adapted to the type and/or the characteristics of the food item and/or the coefficient of friction of the carrying surface such that during cutting, the horizontal force exerted (F.sub.hori) by the cutting device onto the food item does not exceed the frictional force between the food item and the carrying surface.

20. The cutting device according to claim 16, wherein the cutting edge side comprises a smooth cutting edge.

21. The cutting device according to claim 20, wherein the smooth cutting edge is a substantially straight cutting edge.

22. The cutting device according to claim 16, wherein the arm is made of a material selected from: carbon fibers, ceramic material, plastic material, or metal or metal alloy.

23. The cutting device according to claim 16, wherein the length of the arm is adapted to the maximum thickness of the food items, such that when the arm is mounted to the driving unit, the length of the arm is shorter than the distance from the pivot to the food items with a clearance distance between the opposite end of the arm and the top of the food items, where the clearance distance may be in the range of 1 to 9 mm.

24. The cutting device according to claim 16, wherein the carrying surface is concave and shaped such that it substantially follows the path of the cutting blade.

25. The cutting device according to claim 16, wherein the cutting device is adapted for adjusting and/or stopping/starting the rotational movement of the arm and the cutting blade in between successive cuts.

26. A method of cutting food items into smaller food items using a cutting device, where the cutting device is adapted to be placed above a gap extending across a carrying surface of a conveyor system with the cutting plane of the cutting device extending through the gap, where the cutting device is adapted for cutting food items into smaller food items via rotational movement of the cutting device while the food items conveyed by the conveyor system pass the gap, the cutting device comprising: an arm, a cutting blade mounted to one end of the arm, the opposite end of the arm being adapted to be mounted to a driving unit for supplying rotational movement of the arm and thus the cutting blade, wherein the cutting blade is mounted to the arm such that, while cutting a food item into smaller food items, a cutting edge side of the cutting blade engages with the food item under an angle such that the cutting blade exerts with a downwardly facing force onto the food item and towards the carrying surface of the conveyor system during the cutting.

27. A cutting system adapted to cut food items into smaller food items, comprising the cutting device according to claim 16, where the cutting system further comprises: an imaging system for providing image data for an incoming food item, and a processor for controlling the cutting device based on the image data.

28. The cutting system according to claim 27, further comprising at least one further cutting device arranged downstream in relation to the cutting device so as to perform at least one subsequent cut on the food items.

29. The cutting device according to claim 27, where the cutting planes of the cutting devices form an angle between 30 and 120°.

30. The cutting system according to claim 29, where the plane of one or more cutting units performs an angle between 10 and 60° compared to vertical axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

[0058] FIG. 1 shows a cutting device according to the present invention adapted to be placed above a gap extending across a carrying surface of a conveyor system with the cutting plane of the cutting device extending through the gap,

[0059] FIG. 2 shows a zoomed up view of the cutting device in FIG. 1,

[0060] FIG. 3 shows the knife device in FIGS. 1 and 2, where a gap the cutting place of the knife device extends through has a concave shape,

[0061] FIG. 4a,b,c depicts graphically the movement of the cutting device shown in FIG. 1,

[0062] FIG. 5a,b,c depict similarly the movement of the cutting device shown in FIG. 3, and

[0063] FIGS. 6a-f depicts graphically examples of different speed curves of the cutting system, where for simplicity all curves are made with constant acceleration and deceleration.

DESCRIPTION OF EMBODIMENTS

[0064] FIG. 1 shows a cutting device 100 according to the present invention adapted to be placed above a gap 106 extending across a carrying surface of a conveyor system with the cutting plane of the cutting device extending through the gap. The cutting device is adapted for cutting food items 104 into smaller food items via rotational movement of the cutting device 100 as indicated by arrow 108 while the food items 104 conveyed by the conveyor system pass the gap 106.

[0065] The cutting device comprises an arm 101 and a cutting blade 102. The arm is preferably made of light weight material such as, but not limited to, carbon fibers and the like.

[0066] The cutting blade 102 is mounted to one end of the arm, where the opposite end of the arm is adapted to be mounted to a driving unit for supplying the rotational movement 108 of the arm and thus the cutting blade. The cutting blade is mounted to the arm such that, while cutting a food item 104 into smaller food items, a cutting edge side 103 of the cutting blade engages with the food item under an angle 201 such that the cutting blade exerts with a downwardly facing force 107 onto the food item and towards the carrying surface of the conveyor system during the cutting.

[0067] As depicted here, the position of the knife device 100 is adjusted such that the distal end 111 of the edge side 103 of the knife device extends partly through the gap during the cutting, e.g. some millimetres.

[0068] FIG. 2 shows a zoomed up view of the cutting device in FIG. 1, where the angle 201 between cutting edge side 103 and the carrying surface 202 (or a tangent at the point of contact of the carrying surface around the gap) is an acute angle 201 during the cutting. In one embodiment, the acute angle is between 10° and 60°, preferably between 20° and 30°, most preferably around 25° as shown here.

[0069] The angle 201 is adapted to the type and/or the characteristics of the food item and/or the coefficient of friction of the carrying surface such that during cutting, the horizontal force exerted by the cutting device onto the food item does not exceed the frictional force between the food item and the carrying surface.

[0070] FIG. 3 shows the knife device in FIGS. 1 and 2, where the gap 306 has a concave shape, which may be an arc having a similar center point as the pivot point of the driving unit 301 that drives the rotational movement 108 of the cutting device 100. Similar as discussed in relation to FIG. 2, the angle 201 between the cutting edge side 103 and the tangent to the carrying surface 302 is an acute angle during cutting and may e.g. be around 25° in case the food item is boneless chicken leg.

[0071] The cutting edge side preferably comprises a smooth cutting edge which may be a substantially straight cutting edge or curved edge.

[0072] FIG. 4a,b,c depicts graphically the movement of the cutting device 100 shown in FIG. 1 where the carrying surface 510, 511 may be a surface of a single conveyor via e.g. a bypass loop, or two conveyors, where a second end of a first conveyor 510 is placed adjacent to a first end of a second conveyor 511, where the distance between the first and the second end defines the gap 106.

[0073] As shown here, the cutting blade 102 exerts with a downwardly pointing force F.sub.vert and a horizontal force F.sub.hori, where the angle between the cutting blade and the carrying surface discussed previously is such that the friction force pointing opposite to the horizontal force F.sub.hori is equal to prevent side-wise sliding of the food item 104.

[0074] FIG. 5a,b,c depict similarly the movement of the cutting device 100 shown in FIG. 3 where the carrying surface around the gap has a concave shape, e.g. an arc shape where the arc has substantially the same center point as the pivot point of the driving unit. As depicted here, the position of the knife device 100 is adjusted such that the distal end of the edge side 103 of the knife device extends partly through the gap during the cutting, the extension may be in the range of 1 to 9 mm, preferably in the range of 3 to 7 mm, most preferably around 5 mm. By optimizing the shape of the conveyor in relation to the path of the blade it is possible to minimize the effective length of the cutting edge 103. As an example, in case the food item is boneless chicken leg a preferred angle is around 25°. Referring to FIGS. 1 and 2 and the references indicated in these figures, the following applies. Assuming that the maximum thickness h of the boneless chicken legs is 10 mm and that the distance to the arm 101 is as an example 5 mm from the maximum thickness of the boneless chicken legs, hereby referred to as clearance distance h′, and that the depth that the blade exceeds below the carrying surface as an example is 5 mm, hereby referred to as depth d, the length X of the cutting edge side 103 is:

X=(h+h′+d)/sin 25°=20 mm/sin 25°=47.3 mm.

[0075] Accordingly, a very short cutting blade is needed to perform the cutting of such boneless chicken legs, where the primary part of the cutting device is the arm, which as already addressed, can be made of any type of lightweight material.

[0076] FIG. 6a-f depicts graphically examples of different speed curves of the cutting system. For simplicity all curves are made with constant acceleration and deceleration.

[0077] On all curves the Y axis 601 represents the speed of the cutting device with zero speed at the X axis, and the X axis 602 represent the time. The steepness of the line 603 represents acceleration, where the steepness of the line 604 represents the deceleration. In these examples the acceleration and deceleration has the same rate. The dotted line 607 represents the speed where the meat is cut. This speed is the same on all curves.

[0078] The “non-hatched” cross section areas 605 in these example all represent 180° of movement of the cutting system, so that the two cross section areas combined equals one revolution. The hatched cross section area 606 also equals one revolution. The percentage 608 shows the time in relation to constant speed (as seen in FIG. 6c) of the cutting device in each curve example.

[0079] FIG. 6a depict an example on curves including two cuts where the cutting device is standing still between the two cuts.

[0080] FIG. 6b depicts an example on curves including two cuts where the cutting device is accelerating for the second cut immediately after stopping after the first cut.

[0081] FIG. 6c depicts an example on a curve including two cuts where the cutting device is running at constant speed between the first and second cut.

[0082] FIG. 6d depicts an example on a curve including two cuts where the cutting device is decelerating to a constant speed and then accelerate before making the second cut.

[0083] FIG. 6e depicts an example on a curve including two cuts where the cutting device is accelerating to a maximum speed and then decelerate before making the second cut.

[0084] FIG. 6f depicts an example on a curve including two cuts where the cutting device is accelerating to a constant speed and then decelerates before making the second cut.

[0085] As seen on FIGS. 6e-f it is possible to create speed curves where the time between each cut is less than achieved by running at constant speed and still being able to stop the cutting system 180° after making a cut.

[0086] It is clear that the acceleration and deceleration can be lowered from the maximum and creates other curves and cutting speeds. It is also clear that other curves for example: Curves with variable acceleration and deceleration can be created. It is also clear that the curves can be combined to create different time between cuttings in sequences of multiple cuts.

[0087] All FIGS. 6a-f show a situation where the cutting device starts from zero velocity at a position opposite the meat, accelerate to cutting speed, and cut the meat, move one more revolution where a second cut is made and after this the cutting device stops again.

[0088] The calculation of the maximum acceleration/deceleration and the cutting speed can be explained by the following example, wherein values are taken from a prototype:

[0089] The cutting device is able to accelerate to cutting speed in half a revolution, and also stop again in half a revolution.

[0090] The inertia of the cutting device is: 0.00183 kgm.sup.2

[0091] The inertia of the rotor of the drivemotor for the cutting system is: 0.00106 kgm.sup.2

[0092] The available torque from the drive motor is, M: 20 Nm

[0093] The distance from the axis of the cutting system to a concaved conveyor surface: 340 mm.

[0094] Max height of the product to be cut: 20 mm.

[0095] The total inertia of the system, I.sub.rot: (I.sub.tot=I.sub.cut+I.sub.mot) 0.00183+0.00106=0.00289 kgm.sup.2

[0096] The angular acceleration w.sub.rad:

[00001]$\left(w_{\mathrm{rad}}=\frac{M}{\mathrm{Itot}}\right).Math.\frac{20}{0.00289}=6912.Math..Math.\mathrm{rad}.Math.\text{/}.Math.{\sec }^2$

[0097] The angular acceleration w.sub.rot:

[00002]$\left(w_{\mathrm{rot}}=\frac{\mathrm{wrad}}{2*\pi }\right).Math.\frac{6912}{2*\pi }=1100.8.Math..Math.\mathrm{rotations}.Math.\text{/}.Math.{\sec }^2$

[0098] Time to accelerate 180°, T:

[00003]$\left(0.5=T*T*w_{\mathrm{rot}}*0.5.Math.T=\sqrt{\frac{1}{\mathrm{wrot}}}\right).Math..Math.\sqrt{\frac{1}{1100.8}}=0.03.Math..Math.\sec .$

[0099] Cutting speed, rps: (T*W.sub.rot) 0.03*1100.8=33 rps

[0100] Peripheral speed of the blade at the bottom of the product: 33*0.34*2*π=71 m/s

[0101] Peripheral speed of the blade at the top of the product: 33*0.32*2*π=67 m/s

[0102] As seen above it is clear that the inertia of the cutting device is a significant factor for how many cut per minute there can be performed and therefore also on the throughput.

[0103] As it can be seen from the example above, the time to accelerate from 0° position to 180° position is 30 ms. Compared to the prior art example in the beginning of the description that is more than double the operational speed. Also the peripheral speed is increased significantly and is also more constant compared to the prior art example.

[0104] When selecting a motor for a cutting device, the inertia of the cutting device is normally known. The inertia of the rotor for the motors has to be added, to find the total inertia of the rotating system. The available torque from the motor in combination with this total inertia defines how fast the cutting device can be accelerated.

[0105] Typically servo motors are chosen for this type of applications due to a good ratio between torque and the inertia of the rotor.

[0106] In general motors with higher torque have a lower ratio between the torque and the inertia of the rotor. This is due to the fact that the rotor (if everything else is equal) grows in all three dimensions. When the length of the rotor increases the inertia increases proportionally, when the diameter increases the inertia increase more than the torque.

[0107] Therefore, the ratio between the inertia of the cutting device and the rotor of the servo motor decreases, when the inertia of the cutting device increases. Consequently, the inertia of the rotor itself will be a more and more significant factor for defining the maximum acceleration and cutting rate.

[0108] Thus, it is possible to reach a higher acceleration rate when starting with a lower inertia for the cutting device.

[0109] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.