Patent Application
20070028742
The present invention relates to a slicing device for slicing food products, in particular sausage, meat or cheese blocks, having a rotating cutting blade mounted so as to be displaceable parallel to its axis of rotation. The present invention relates to a method for axial displacement of the cutting blade and to the use of axially displaceable counterweights for stabilising running of a cutting blade of a cutting machine, to the use of the axial displacement of the cutting blade of a slicing machine for adjusting the zero point and to the use of the axial displacement of the cutting blade for adjusting the cutting gap between the cutting blade and a cutting guide.
These days, slicing machines sever slices from a block-form food product, for example a sausage, ham or cheese block, at relatively high rates. The food products lie on a product support and are conveyed gradually or continuously thereby towards the cutting blade. To achieve very high cutting performance, it is necessary to provide idle cuts, i.e. movements of the cutting blade during which no slice is severed from the block of food product. To produce idle cuts, it is possible on the one hand for the food product to perform a retraction stroke directed away from the cutting plane. It is also possible to produce an idle cut by preferably axial displacement of the blade.
Such axial displacement of the cutting blade is taught for example in patent specification no. 15 49 52, wherein the axial retraction stroke of the blade of the slicing machine described therein is produced by a cam disk coupled to the drive, such that axial displacement of the blade is impossible independently of the rotational speed of the blade. A further slicing machine with an axially displaceable blade is taught in DE 4214264 A1, wherein in the present case axial movement is effected by an actuating cylinder, such that movement is only possible between two end points and not adapted to the particular product.
The object of the present invention is therefore to provide a slicing machine which does not exhibit the disadvantages of the prior art.
The object is achieved according to the invention by a slicing machine according to claims 1 and 3. Preferred embodiments of the slicing machine according to the invention are described in subordinate claims 2 and 4 to 9.
According to the invention, the slicing machine comprises a rotating cutting blade, which is mounted so as to be displaceable parallel to its axis of rotation. Displacement of the cutting blade is effected according to the invention by a feedback-controlled drive. It was extremely surprising to the person skilled in the art and not at all expected that very precise, very rapid axial displacement of the cutting blade is possible with such a drive. The position of the cutting blade relative to its zero point is known at all times. The feedback-controlled drive makes it possible to adapt the axial displacement, in particular with regard to distance and acceleration, to the particular instance of use. The optimum is a function inter alia of cutting efficiency, of the product, in particular of product geometry and product temperature, of blade geometry, of the position of the blade relative to the product and/or of slice thickness. Furthermore, the slicing machine according to the invention makes it possible to achieve the widest possible range of displacement profiles, for example the axial displacement may take a sinusoidal course. The optimum displacement of the cutting blade may be stored in a computer associated with the cutting machine. The slicing machine according to the invention is simple and economic to produce and operate.
In a preferred embodiment, the slicing machine comprises a counterweight, which may be displaced in the opposite direction from the cutting blade. This embodiment of the present invention has the advantage that the acceleration forces and moments are suppressed during axial displacement of the blade, such that the slicing machine is prevented to the greatest possible extent from vibrating.
Through separate adjustment of the counterweight independently of the axial displacement of the blade, forces and/or moments which arise for example as a result of blade imbalances caused by wear or sharpening may be eliminated. This adjustment of the blade takes place after attachment of the blade or during operation. The mass of the counterweight does not have to correspond to the mass of the cutting blade. Furthermore, the counterweight does not have to be symmetrical, in particular not rotationally symmetrical.
The present invention further provides a slicing machine for slicing food products, in particular blocks of sausage, meat or cheese, having a rotating cutting blade, which is mounted so as to be displaceable parallel to its axis of rotation, wherein it comprises a counterweight which is displaceable in the opposite direction from the cutting blade.
This slicing machine according to the invention has the advantage that acceleration forces or moments which arise during axial displacement of the blade are compensated. As a consequence, the slicing machine runs virtually without vibration, such that in particular the machine frame may be of substantially lighter construction. Furthermore, the cutting blade runs substantially more smoothly, such that more precise cuts are possible. Through separate adjustment of the counterweight independently of the axial displacement of the blade, forces and/or moments which arise for example as a result of blade imbalances caused by wear or sharpening may be eliminated. This adjustment of the blade takes place after attachment of the blade or during operation.
In a preferred embodiment, displacement of the cutting blade and of the counterweight is effected in each case by a feedback-controlled drive. This feedback-controlled drive has the advantage of making possible very precise, very rapid axial displacement of the cutting blade and the counterweight. The positions of the cutting blade relative to its zero point and of the counterweight are known at all times. The feedback-controlled drive makes it possible to adapt the particular axial displacement, in particular with regard to distance and acceleration, to the particular instance of use. Optimum displacement of the cutting blade is a function inter alia of cutting efficiency, of the product, in particular of product geometry and product temperature, of blade geometry, of the position of the blade relative to the product and/or of slice thickness.
Furthermore, the slicing machine makes it possible to achieve the widest possible range of displacement profiles, for example the axial displacement may take a sinusoidal course. The optimum displacement of the cutting blade and counterweight may be stored in a computer associated with the cutting machine. The slicing machine according to the invention is simple and economic to produce and operate.
Preferably, however, the slicing machine comprises just one preferably feedback-controlled drive for displacement of the cutting blade and of the counterweight. This embodiment has the advantage that just one drive is required for both movements. Reference is made to the above statements with regard to the advantages of feedback-controlled drive of the displacement.
The following statements apply to both the above-stated slicing machines according to the invention.
Any blade known to the person skilled in the art is suitable as cutting blade. Mention will be made here, by way of example, only of the circular blade, helical blade and crescent-shaped blade. The circular blade advantageously rotates in planetary manner. The blade is set in rotation by a drive. This drive is preferably feedback-controlled.
The counterweight may be any weight with which it is possible to eliminate the acceleration forces or acceleration moments and/or to eliminate forces or moments caused by blade imbalances or the like. The person skilled in the art will recognise that the mass of the counterweight does not have to correspond to the mass of the cutting blade. The same applies to the acceleration time profile and the displacement distance of the counterweight, which do not have to correspond to the acceleration profile or the axial displacement respectively of the blade. Furthermore, the person skilled in the art will recognise that the counterweight does not have to be symmetrical, in particular not rotationally symmetrical.
Displacement of the blade and/or of the counterweight is preferably to the greatest possible extent without play.
Displacement of the cutting blade and/or of the counterweight preferably takes place independently of the rotational speed of the cutting blade.
In another preferred embodiment of the slicing machine according to the invention, the cutting blade comprises a drive shaft and the cutting blade and/or the counterweight are mounted displaceably along the drive shaft. The drive shaft preferably comprises a controllable drive.
Furthermore, displacement of the cutting blade and/or of the counterweight is preferably effected with a spindle, which is particularly preferably arranged within the drive shaft. This spindle is preferably capable of feedback-controlled drive and preferably interacts with the thread of at least one sleeve (nut), which is connected with the cutting blade or with the counterweight. However, the slicing machine preferably comprises two sleeves, wherein one interacts with the cutting blade and one with the counterweight. These sleeves preferably have different threads, wherein the threads preferably differ in thread direction and/or lead angle. This embodiment of the present invention makes it possible for both the cutting blade and the counterweight to be displaced with one drive. The connection between the sleeves and the spindle is preferably to the greatest possible extent without play. This may be achieved for example by pretensioning of the sleeves, such that they always lie against the same flank of the spindle.
Preferably, the displacement mechanism for the blade and/or for the counterweight undergoes forced temperature control, preferably cooling. Very particularly preferably, the drive of the cutting blade and/or its bearing system is additionally forcibly cooled. The respective temperature control may be effected using liquids, preferably aqueous liquids or oil, and/or gas.
The present invention further provides a method for axial displacement of cutting blades during operation, in which a counterweight is displaced in the opposite direction from the cutting blade.
The method according to the invention has the advantage that no or only slight vibration occurs during displacement of the cutting blade. The method according to the invention is simple and cheap to carry out.
Preferably, displacement of the cutting blade and of the counterweight takes place synchronously.
It is also preferable for displacement of the cutting blade or of the counterweight to take place with one drive.
The present invention further provides the use of axially displaceable counterweights to stabilise running of a cutting blade of a slicing machine.
It was extremely surprising to the person skilled in the art and not at all expected that forces and/or moments caused for example by wear or sharpening may be compensated by the displacement of counterweights.
The present invention further provides the use of axial displacement of a cutting blade to adjust the zero point of the cutting blade. The zero point of the cutting blade is the point at which the blade finds itself no longer in contact with the cutting guide.
This use according to the invention has the advantage that adjustment of the zero point relative to the so-called cutting guide may take place virtually automatically. The position of the cutting guide has only to be changed extremely rarely, such that adjustment of the zero point, which has to be performed each time the blade is sharpened, may be carried out automatically.
Preferably, when the zero point is adjusted, the torque of the blade drive is measured. As soon as this increases, a control unit associated with the slicing machine recognises that there is contact between the cutting blade and the cutting guide and moves the blade away from the cutting guide again until the torque has reduced again accordingly. This point is the new zero point. The zero point may be stored and used for example for automatic adjustment of the cutting gap.
Adjustment of the zero point may take place on machine start-up or during operation. For example, the zero point may be checked at regular intervals during operation of the machine and optionally readjusted.
The present invention further provides feedback-controlled axial displacement of the cutting blade for adjustment of the cutting gap between the cutting edge of the cutting blade and a cutting guide.
This use according to the invention has the advantage that the cutting gap may be modified during operation or adapted to altered operating conditions. This makes it possible to produce the smallest possible cutting gap and thus very constant slice thicknesses.
Preferably, use according to the invention compensates expansion of the blade resulting from thermal expansion or centrifugal forces and wear caused by operation, in order to produce a slice thickness which as far as possible remains uniform.
It is also preferred for the cutting gap to be adjusted automatically via a display and no longer to require measurement or adjustment by hand.
The mechanical behaviour of the blade is preferably stored as a model and/or by means of characteristic diagrams in the machine control system, for example a computer. These data are used for adjustment or readjustment of the cutting gap when the cutting blade is in operation, such that at any time during operation, i.e. for example at any rotational speed and at any temperature, it is possible to operate with an at least virtually constant cutting gap.
The present invention further provides a device for slicing food products having a blade exhibiting a cutting plane and driven in rotation by a drive shaft and having a cutting edge, the blade being mounted so as to be displaceable parallel to its drive shaft for adjustment of the cutting gap between the cutting plane and the cutting edge and the device comprising an adjusting means with which the cutting gap may be established.
It was extremely surprising to the person skilled in the art and not at all expected that it would be possible with the device according to the invention to effect automatic adjustment of the cutting gap of a slicer. The device according to the invention is simple and economic to produce and operate.
According to the invention, the device for slicing food products comprises an adjusting means with which the cutting gap may be fixed. For this purpose, the adjusting means is brought into a given position and then the blade is displaced axially until it comes into contact with the adjusting means or until a given distance exists between the adjusting means and the cutting plane of the blade. The distance between the cutting plane and the cutting edge then corresponds to the desired cutting gap.
Preferably, the adjusting means is therefore an adjusting limit stop, towards which the blade moves by axial displacement. As soon as the blade comes into contact with the adjusting limit stop, axial displacement of the blade is terminated.
Preferably, the adjusting limit stop may be moved between a basic position and an adjusting position. In the adjusting position, adjustment of the cutting gap takes place. In the basic position, the adjusting limit stop is at a certain distance from the blade. This embodiment of the present invention has the advantage that slicing of the food product block is not impaired by the adjusting limit stop.
Adjustment of the adjusting limit stop between the basic and the adjusting positions may take place in any manner familiar to the person skilled in the art. Only manual adjustment is mentioned here by way of example. However, adjustment is preferably effected by an actuator, such that very precise positioning of the adjusting means and thus very precise adjustment of the cutting gap is possible.
Detection of contact between the blade and the adjusting means may take place in any manner familiar to the person skilled in the art. Preferably, however, the adjusting limit stop comprises a contact sensor.
Preferably, axial displacement of the blade is effected by means of a motor, preferably a servomotor. In this embodiment of the device according to the invention, the current consumption of the motor may be used to detect contact with the adjusting means.
In a preferred embodiment of the present invention, the position of the adjusting means, preferably of the adjusting limit stop, and thus the width of the cutting gap may be selected particularly preferably by means of a display. The machine operator selects the desired cutting gap on the display and the adjusting limit stop travels automatically into the corresponding position when the cutting gap is next adjusted.
Adjustment of the cutting gap preferably takes place when the blade is at a standstill. Adjustment of the cutting gap may also take place, however, when the blade is rotating, for example in order to compensate changes to the cutting plane caused by rotational speed and/or temperature.
The device according to the invention has the advantage, in particular, that the axial position of the blade no longer has to be changed after it has come into contact with the adjusting limit stop or after detection of a certain distance between the blade and the cutting edge.
The present invention further provides a method for adjustment of the cutting gap using the device according to the invention, in which an adjusting limit stop is moved from its basic position into its adjusting position corresponding to the desired cutting gap and the blade is displaced axially until it comes into contact with the adjusting limit stop.
The method according to the invention is simple and cheap to carry out. With the method according to the invention, any desired cutting gap, which may for example be preselected on a display, may be set before or during operation of the blade.
Preferably, the adjusting limit stop is brought into its basic position after adjustment of the cutting gap.
The present invention further provides a device for slicing food products, having a rotating cutting blade, which is displaceable parallel to its axis of rotation, wherein displacement is effected with at least one means comprising a first and second end, the position of which relative to one another may be modified.
It was extremely surprising to the person skilled in the art and not at all expected that it would be possible with such simple means to move the blade to and fro between two positions.
The means is preferably a coupling rod or a leaf spring.
It is also preferable for the first and the second end of the means, for example the coupling rod, to be twisted relative to one another, such that the length thereof relative to the axis of rotation is reversibly reduced.
In another preferred embodiment of the present invention, the means, for example a leaf spring, is bent and released again.
The inventions are explained below with reference to
Since the exemplary slicing machine comprises feedback-controlled drives, this may be used for adjustment of the zero point of the cutting blade. For this purpose, the blade 2 is firstly set in rotation while at a distance from the cutting guide 15 and slowly moved in the direction of the cutting guide 15. In the process, the torque required for constant drive of the cutting blade 2 is measured, for example. As soon as this torque increases, i.e. the cutting blade is in engagement with the cutting guide 15, the axial movement of the blade is stopped and optionally reversed incrementally. The setting located in this way is the new zero point. This embodiment has the advantage that the cutting guide does not have to be displaced relative to the blade, as in the prior art, and that location of the zero point may be effected automatically in the slicing machine according to the invention and be repeated during the slicing process. The zero point is stored by the slicing machine according to the invention in a control unit associated with the machine and may be used for adjustment of the cutting gap.
Furthermore, the feedback-controlled drive may be used for adjustment or readjustment of the gap width. The person skilled in the art will recognise that the cutting blade 2 is shaped in the manner of a key. During operation of the cutting blade 2, the latter expands for example due to thermal effects and/or centrifugal forces. The degree of expansion is accordingly a function inter alia of the speed of the cutting blade and is either known to the person skilled in the art or measurable. In the case in particular of a slicing machine in which the rotational speed of the cutting blade is not constant, but also after a cold start, expansion may be balanced by a relative movement between spindle and drive shaft, such that with the slicing machine according to the invention cutting may be performed with a constant cutting gap during the entire cutting process and thus food product slices may be achieved which are of a very constant thickness. Through automatic adjustment or readjustment of the cutting gap, cutting may be performed with substantially smaller cutting gaps than in the prior art, which has a positive effect on cutting quality. The drive 5, 7 of the blade 2 and/or the adjusting mechanism 6, 8, 9 of the blade 2 and/or of the counterweight 4 may be temperature-controlled, preferably cooled, in the present slicing machine.
Once the adjusting limit stop has been moved to the left, the blade, as shown in
Adjustment of the adjusting gap may take place prior to slicing of a new food product block and/or after a blade change. With the device according to the invention, it is possible to adjust the cutting gap both when the blade is at a standstill and when it is rotating. Adjustment of a rotating blade has the advantage that changes to the cutting plane, for example as a result of centrifugal forces or thermal influences, may be compensated.
Twisting of the coupling rods is effected by a temporary change in the rotational speed of the means 39 in comparison to the rotational speed of the means 40, wherein the change in rotational speed has to be effected in such a way that either the rotational speed of the means 39 is slowed down in comparison to the rotational speed of the means 40 or the rotational speed of the means 40 is increased in comparison to the rotational speed of the means 39. After termination of the twisting movement, the two means 39, 40 once again rotate at the same speed. A larger distance may again be achieved between the blade 27 and the cutting guide 28 in such a way that the coupling rods 33 are brought into a vertical position. This is effected either in that the rotational speed of the means 39 is accelerated for a short time and/or in that the rotational speed of the means 40 is reduced for a short time.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 33 661.3 | Jul 2003 | DE | national |
| 103 59 149.4 | Dec 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/08265 | 7/23/2004 | WO | 7/27/2006 |
