EP2389279A1

EP2389279A1 - Device and method for adjusting a blade clearance on a cutting device

Info

Publication number: EP2389279A1
Application number: EP10708122A
Authority: EP
Inventors: Günther Weber
Original assignee: Weber Maschinenbau GmbH Breidenbach
Current assignee: Weber Maschinenbau GmbH Breidenbach
Priority date: 2009-03-05
Filing date: 2010-03-03
Publication date: 2011-11-30
Anticipated expiration: 2030-03-03
Also published as: ES2429020T3; ES2429020T5; US20120060659A1; WO2010099961A1; EP2389279B2; DE102009011860A1; EP2389279B1

Abstract

The invention relates to a device and to a method for adjusting a blade clearance on a cutting device for slicing a product, in particular a food product (18), wherein the cutting device has a cutting blade (14) which can be rotatably driven in a cutting plane (12), a cutting edge (24) and an adjustment apparatus (28) by which the cutting blade (14) and the cutting edge (24) can be moved relative to each other perpendicular to the cutting plane (12).

Description

DEVICE AND METHOD FOR ADJUSTING A CUTTING COLUMN ON A CUTTING DEVICE

The invention relates to a device and a method for adjusting a cutting gap on a cutting device for cutting a product, in particular food product, wherein the cutting device has a knife rotatably driven in a cutting plane, a cutting edge and an adjusting device through which the knife and the cutting edge perpendicular to Cutting plane are movable relative to each other.

Such a device and method are basically known and serve to maintain the cutting gap, i. in other words, adjust the distance between the cutting plane and the cutting edge so that optimal and consistent cutting and depositing quality as well as maximum tool life are achieved.

In principle, the smaller the cutting gap, the better the product can be cut. This is especially true when the knife no longer has the optimum sharpness. For the following reasons, however, the cutting gap could hitherto not be set arbitrarily small:

The knives known cutting devices, especially known Hochleistungsslicer that can perform up to 2000 cuts per minute, are typically designed as a circular or sickle blade. These knives are elaborately manufactured products, may be occupied by plan impact tolerances of up to 0.5 mm due to the production.

Conventionally, the distance between the knife and the cutting edge is measured at standstill by manual measurement or by means of a distance sensor, such as a knife. a laser probe, an ultrasonic sensor or an inductive sensor. Since, due to the punctual nature of the measurement, it is unclear whether the measured distance is actually a maximum or a minimum distance between the blade and the cutting edge, the possible blade impact tolerance must always be added to the measurement result. The setting of a cutting gap, which is less than the plan impact tolerance, is therefore not possible.

The distance measurement or setting of the cutting gap with the knife stationary also has the disadvantage that this does not take into account that the knife bends in the rotating state with increasing speed. This effect can increase the width of the cutting gap by several tenths of a millimeter.

In addition, the blade deforms during a cutting process by the force of the product to be cut. This deformation depends on the type of knife used as well as the type of product to be sliced and may also be in the range of several tenths of a millimeter, with the direction of deformation depending on the particular cutting parameters as well as the type of knife and product. The invention is therefore based on the object to provide a device and a method which or which, in particular automatically, enables an optimal cutting gap setting.

To achieve the object, a device having the features of claim 1 and a method having the features of claim 6 are provided.

The invention is based on the general idea, not to make the adjustment of the cutting gap with a stationary blade, but with a rotating blade. This has the particular advantage that a rotation-related bending of the knife in the actually occurring dimension, i. so correctly, can be considered in the adjustment of the cutting gap. Due to the cutting gap setting with a rotating knife, the cutting gap can also be adjusted so that it actually corresponds to a desired minimum distance between the knife and the cutting edge. As a result, an optimal cutting gap setting is possible, taking into account the events actually present during a cutting process, such as flattening and / or bending of the knife.

In concrete terms, the invention provides for detection of vibrations generated by the rotating blade and control of the adjusting device as a function of the detected vibrations. This measure would be based on the finding that the rotating blade produces a characteristic vibration profile in accordance with its configuration and shape or deformation, wherein the vibration profile in the freely rotating state of the blade is different than in a state in which the blade touches the cutting edge , Taking advantage of this difference in the vibration profile with a rotating knife, a zero distance of the knife to the cutting edge determined and starting from this zero distance exact adjustment of the cutting gap can be made. Consequently, the device according to the invention and the method according to the invention make it possible to automatically set an exact cutting gap while taking into account the blade tolerances and blade deflection.

Advantageous embodiments of the invention are described in the dependent claims, the description and the drawings.

According to one embodiment of the device according to the invention, the detection means for detecting sound waves, in particular of structure-borne sound waves, formed. In other words, the detected vibrations are mechanical in nature, but need not necessarily be perceptible by the human ear. Rather, these may be vibrations caused by the rotating blade in the components of the cutting device.

In order to detect a contact of the rotating blade with the cutting edge particularly reliable, the detection means is preferably arranged in the region of the cutting edge. In principle, the detection means can be mounted on the cutting edge itself.

Advantageously, however, the detection means is mounted on a support structure for the cutting edge and in particular embedded in the support structure. By attaching the detection means to the support structure, an exchange of the cutting edge, which is subject to a certain wear, regardless of the detection means take place and in particular, without the detection means for this purpose of the Cutting edge dismantled or needs to be disconnected from an electrical connection. The replacement of the cutting edge is thereby considerably simplified.

The detection means may comprise one or more structure-borne sound sensors. A structure-borne sound sensor has no preferred detection direction, but rather detects an overall picture of the present vibrations. The or each structure-borne noise sensor can be fastened to an outer surface of the carrier structure, in particular on a rear side of the carrier structure facing away from the cutting plane. A simpler cleaning of the cutting device, in particular in the region of the cutting edge, is possible if the or each structure-borne sound sensor is integrated into the support structure, for example, a correspondingly provided recess or in a correspondingly provided cavity of the carrier structure. If several structure-borne noise sensors are used, it is advantageous to use them across the width of the support structure, i. ie parallel to the cutting plane, distributed to arrange. In this case, the plurality of structure-borne sound sensors can each be accommodated in a separate depression or a separate cavity or in a common depression or a common cavity.

According to a further embodiment, the control unit is designed to evaluate the detected vibrations with respect to their amplitude and / or frequency. This allows monitoring of the vibrations generated by the freely rotating blade and in particular the

Detecting a deviation of the detected vibrations from the characteristic vibration profile of the freely rotating blade, for example when the blade touches the cutting edge. As a result, the control unit is able to determine a zero distance between the blade and cutting edge. According to an advantageous embodiment of the method according to the invention, a reference vibration pattern is recorded while the blade is spaced from the cutting edge. The reference vibration pattern corresponds to the characteristic vibration profile of the freely rotating blade which does not touch the cutting edge. The reference vibration pattern is not necessarily constant over the life of a blade, but may be affected by various factors such as the quality of the blade bearing, the condition of the blade, the chop or other deformation of the blade.

Preferably, the reference vibration pattern is picked up while the blade is accelerated from a stationary state. This makes it possible to record a new reference oscillation pattern after each replacement of the knife and to use the cutting gap setting, which allows an individual cutting gap to be set individually for each newly installed knife.

Alternatively or additionally, the reference oscillation pattern can be recorded while the distance between the knife and the cutting edge is reduced. This includes on the one hand the case that a newly installed knife is moved back to the cutting edge, as well as the case that the rotating blade during operation, e.g. for readjustment of the cutting gap, first away from the cutting edge and then moved back to this. Alternatively, the cutting edge can be moved up to a fixed knife.

According to a further embodiment of the method, a zero distance of the knife to the cutting edge is determined by the distance between the knife and the cutting edge after the recording of a reference Vibration pattern is reduced until a significant deviation of the detected vibrations of the reference vibration pattern is detected. For example, a significant deviation can be detected if the amplitude of at least one detected oscillation exceeds the amplitude of the reference oscillation pattern by a predetermined amount.

Thus, it will be readily understood that when the blade contacts the cutting edge, vibration is generated in the cutting edge or in a cutting edge support structure whose amplitude is significantly greater than that of the vibrations of the reference vibration pattern. If this amplitude difference exceeds a predetermined threshold, then it can be assumed that the knife comes into contact with the cutting edge.

The reliability of this detection of the zero distance between the blade and the cutting edge can be further increased by relating the frequency of a detected deviation from the reference vibration pattern to the rotational speed of the rotating blade. Thus, a deviation from the reference vibration pattern is generated with increased probability by the cutting edge touching blade when the frequency of the detected deviation at least substantially coincides with the rotational speed of the blade. In this way, a deviation from the reference vibration pattern caused by the rotating blade can be distinguished, for example, from a deviation caused by external influences, such as knocking with a tool in the vicinity of the cutting device. Advantageously, the distance between the knife and the cutting edge for setting the desired cutting gap is increased starting from the determined zero distance. The specific zero distance is in other words used as the zero point for the adjustment of the cutting gap. If the adjusting device has a positioning motor for moving the blade or the cutting edge, then the adjustment of the desired cutting gap can take place on the basis of the signals of a rotary encoder which makes it possible to monitor the adjustment of the blade or of the cutting edge relative to the zero point. A distance sensor for determining the absolute distance between the cutting blade and the cutting edge can thus be dispensed with.

Another object of the invention is also the use of a structure-borne sound sensor for determining a zero distance between the blade and the cutting edge in the setting of a cutting gap on a

Cutting device for slicing a product, in particular a food product, which has a knife drivable in a cutting plane, a cutting edge and an adjusting device, by means of which the knife and the cutting edge are movable relative to each other perpendicular to the cutting plane.

The invention will be described purely by way of example with reference to an advantageous embodiment with reference to the accompanying drawings. Show it:

Figure 1 is a schematic side view of a cutting device with a device according to the invention for cutting gap setting. and Fig. 2 is a schematic view of the front of a

Cutting edge of the cutting device of Fig. 1.

The cutting device shown in FIGS. 1 and 2 for cutting a product, in particular a food product 10, has a knife 14 which can be driven in a rotating manner in a cutting plane 12 and which is fastened to a cutter head 16. In the present exemplary embodiment, the knife 14 is a sickle knife, which rotates exclusively about its central axis 18 and thereby describes a circumferential circle, which is designated in FIG. 2 by the reference numeral 14 '. Alternatively, the cutter head 16 may be driven in a planetary rotation, so that the blade 14 rotates in the cutting plane 12 in addition to its own rotation about the central axis 18 on a planetary orbit.

The food product 10 to be sliced rests on a product support 20, on which it is moved in the direction of the cutting plane 12. In the present exemplary embodiment, the product support 20 comprises a conveyor belt 22. Instead of the conveyor belt 22, however, the product support 20 may also comprise a stationary support on which the food product 10 is pushed in the direction of the cutting plane 12 with the aid of a gripper. Of course, such a gripper can also be used in conjunction with the conveyor belt 22.

The front end of the product support 20 forms a cutting edge 24, with which the knife 14 cooperates during cutting. So that the cutting edge 24 can be exchanged for adaptation of the cutting device to the respective application or also with excessive wear, it is releasably attached to a support structure 26 which extends transversely to the conveying direction of the food product 10 below the conveyor belt 22nd extends. The support structure 26 is also referred to herein as a cutting edge receiving.

Between the cutting plane 12 and the cutting edge 24, a cutting gap .DELTA.x is formed, which is shown greatly enlarged in FIG.

The cutter head 16 and the blade 14 fastened thereto are displaceably mounted on an electric adjusting device 28 in such a way that the blade 14 can be moved towards or away from the cutting edge 24, which is indicated by a double arrow 30 in FIG. Alternatively, it would also be possible to support the blade 14 stationary and to move the cutting edge 24 relative thereto. For automatic control of the adjusting device 28, a control unit 32 is provided.

On the support structure 26, a structure-borne sound sensor 34 is mounted, which is in communication with the control unit 32. In the present embodiment, the structure-borne sound sensor 34 is embedded in the support structure 26, i. arranged in a correspondingly formed cavity (not shown) of the support structure 26. In principle, however, it is also conceivable to use the structure-borne noise sensor 34 on an outer surface of the

To fix support structure 26, in particular on a rear side of the support structure 26 facing away from the cutting plane 12.

Furthermore, in the present exemplary embodiment only a structure-borne sound sensor 34 is used, which is arranged essentially centrally in the support structure 26. It is also conceivable, however, to use a plurality of structure-borne noise sensors, which can be distributed over the width of the support structure 26, ie viewed transversely to the conveying direction of the food product 10. The structure-borne sound sensor 34 detects independently of direction the mechanical vibrations or vibrations present in the support structure 26, in other words the structure-borne noise induced in the support structure 26. The vibrations detected by the structure-borne sound sensor 34 are evaluated by the control unit 32 with regard to their amplitudes or frequencies, as will be explained in more detail below.

An optimum cutting result is achieved if - in addition to other factors known per se - the food product 10 is cut open with a possibly sharpest knife 14 and with the smallest possible cutting gap Δx. Since the blade 14 becomes dull after a certain number of cuts, the blade 14 must be replaced at regular intervals. The cutting gap must be readjusted after each blade change. Another reason for the replacement of the blade 14 may also be the change of equipment, in particular the blade 14 and / or the cutting edge 24, for adapting the cutting device to another application.

To set the cutting gap, the newly installed blade 14 is initially accelerated from its stationary state to its operating speed, which may for example be in the range between 500 and 2000 revolutions per minute. Here, the operating speed is understood as meaning that rotational speed of the blade 14 at which the food product 10 is ultimately cut open.

As soon as the blade 14 has reached a certain measuring speed, for example its operating speed, the vibrations induced in the carrier structure 26 are detected by the structure-borne sound sensor 34 and stored as a reference vibration pattern in a memory of the control unit 32. After the recording of the reference oscillation pattern, the knife 14 is approached by the adjusting device 28 in discrete steps to the cutting edge 24 until the control device 32 detects a significant deviation of the vibrations detected by the structure-borne sound sensor 34 from the reference oscillation pattern.

A significant deviation may be, for example, that the amplitude of one or more oscillations is increased in relation to a mean or maximum oscillation amplitude of the reference oscillation pattern such that the resulting amplitude difference exceeds a predetermined threshold, while at the same time the frequency of this oscillation or oscillations with increased amplitude with the rotational speed of the blade 14 substantially matches.

If the control unit 32 has detected in the vibrations detected by the structure-borne noise sensor 34 such a significant deviation from the reference vibration pattern, then the control unit 32 assumes that there is contact between the blade 14 and the cutting edge 24.

As a result, the movement of the blade 14 toward the cutting edge 24 is stopped and the instantaneous position of the blade 14 is defined as zero clearance. In other words, the controller 32 assumes that the distance between the knife 14 and the cutting edge 24 is zero in this situation.

Starting from this zero distance, the knife 14 - controlled by the control unit 32 - then moved away by a predetermined amount of length from the cutting edge 24 to set a desired cutting gap .DELTA.x. This desired cutting gap Δx is present Preferably just chosen so large that a deformation of the blade 14 during the cutting process does not lead to a knife break, but at the same time so small that an optimum cutting result is achieved.

The setting of the desired cutting gap can be effected in a manner known per se using a rotary encoder connected to the control unit 32, which monitors the rotation of an output shaft of an electric motor of the adjusting device 28 responsible for the adjustment of the blade 14.

Once the desired cutting gap .DELTA.x is set, the cutting of the food product 10 can be started by supplying it to the knife 14 by means of the conveyor belt 22 and / or a product gripper.

As has been explained above, in the present exemplary embodiment, the reference oscillation pattern is not deposited until the blade 14 has reached its measuring rotational speed. This can be, for example, the operating speed at which the food product 10 is then cut open. In principle, however, it is also conceivable to define those oscillations as reference oscillation patterns which are already recorded during a lower rotational speed, for example in the range between 500 and 1200 revolutions per minute.

If the determination of the zero distance between knife 14 and

Cutting edge 24 at a deviating from the measuring speed of the blade 14, so this different speed of the blade 14 in the detection and evaluation of a significant deviation of the detected vibrations of the reference vibrations must be considered. It should also be noted that neither the recording of the reference vibration pattern, nor the determination of the zero distance between the blade 14 and cutting edge 24 a constant speed of the blade 14, that is, a steady operation of the blade 14, requires. Rather, both the recording of the reference vibration pattern and the determination of the zero distance between the blade 14 and the cutting edge 24 and / or the subsequent adjustment of the desired cutting gap .DELTA.x occur while the rotational speed of the blade 14 is still increasing. In this way, the setting of the desired cutting gap .DELTA.x can be completed until the operating speed of the blade 14 is reached, so that the fastest possible continuation of the cutting process after an exchange of the blade 14 is possible.

Finally, it should be noted that the adjustment of the desired cutting gap Ax can not be done only after an exchange of the blade 14. Rather, it is also possible to repeat the determination of the zero distance between knife 14 and cutting edge 24 and the subsequent adjustment of the desired cutting gap Ax during a running cutting operation, for example during so-called idle cuts, in which the food product 10 is temporarily out of the engagement area of the knife 14 is withdrawn. This allows a readjustment of the cutting gap Δx even during operation. LIST OF REFERENCE NUMBERS

10 food product

12 cutting plane

14 knives

14 'circumference circle

16 knife head

18 central axis

20 product edition

22 conveyor belt

24 cutting edge

26 carrier structure

28 adjusting device

30 double-headed arrow

32 control unit

34 structure-borne sound sensor

Claims

claims

1. A device for setting a cutting gap (Δx) on a cutting device for slicing a product, in particular a food product (10), wherein the cutting device comprises a cutting plane (12) rotatably driven knife (14), a cutting edge (24) and an adjusting device ( 28) through which the knife (14) and the cutting edge (24) perpendicular to the cutting plane (12) are movable relative to each other, characterized by a detection means (34) for detecting vibrations generated by the rotating blade (14) and one with the control unit (32) connected to the detection means (34) for controlling the adjusting device (28) as a function of the detected vibrations.

2. Apparatus according to claim 1, characterized in that the detection means (34) for detecting sound waves, in particular structure-borne sound waves, is formed and in particular comprises at least one structure-borne sound sensor.

3. Apparatus according to claim 1 or 2, characterized in that the detection means (34) in the region of the cutting edge (24) is arranged.

4. Device according to one of the preceding claims, characterized in that the detection means (34) on a support structure (26) for the cutting edge (24) is mounted and in particular in the support structure (26) is embedded.

5. Device according to one of the preceding claims, characterized in that the control unit (32) is adapted to evaluate the detected vibrations in terms of their amplitude and / or frequency and / or to determine a zero distance between the blade (14) and cutting edge (24) ,

6. A method for setting a cutting gap (.DELTA.x) on a cutting device for cutting a product, in particular food product (10), wherein the cutting device in a cutting plane (12) rotatably driven knife (14), a cutting edge (24) and an adjusting device ( 28), by which the knife (14) and the cutting edge (24) perpendicular to the cutting plane (12) are movable relative to each other, characterized in that by means of a detection means (34) by the rotating blade

(14) vibrations are detected and by means of a detection means connected to the control unit (32), the adjusting device (28) is controlled in response to the detected vibrations.

7. The method according to claim 6, characterized in that by means of the detection means (34) by the rotating blade (14) generated sound waves, in particular structure-borne sound waves, are detected.

8. The method according to claim 6 or 7, characterized in that the vibrations, in particular structure-borne sound waves, in the region of the cutting edge (24) are detected.

9. The method according to any one of claims 6 to 8, characterized in that a reference vibration pattern is recorded while the knife (14) to the cutting edge (24) is spaced.

10. The method according to claim 9, characterized in that the reference vibration pattern is recorded while the knife (14) is accelerated from a stationary state.

11. The method of claim 9 or 10, characterized in that the reference vibration pattern is recorded while the distance between the blade (14) and the cutting edge (24) is reduced.

12. The method according to any one of claims 6 to 11, characterized in that a zero distance of the blade (14) to the cutting edge (24) is determined by the distance between the blade (14) and cutting edge (24) is reduced after receiving a reference vibration pattern until a significant deviation of the detected vibrations from the reference vibration pattern is detected.

13. The method according to claim 12, characterized in that a significant deviation is detected when the amplitudes of detected vibrations exceed the amplitudes of the reference vibration pattern by a predetermined amount.

14. The method according to claim 12 or 13, characterized in that the distance between the blade (14) and cutting edge (24) for adjusting the cutting gap (.DELTA.x) starting from the particular

Zero distance is increased.

15. Use of a structure-borne sound sensor (34) for determining a zero distance between the blade (14) and cutting edge (24) when setting a cutting gap (Δx) on a cutting device for slicing a product, in particular food product (10), which in a cutting plane ( 12) has a rotationally drivable blade (14), a cutting edge (24) and an adjusting device (28) through which the blade (14) and the cutting edge (24) are movable relative to each other perpendicular to the cutting plane (12).