Abstract:
The disclosure relates to a method for operating a food slicing device in which a sensor device with a sensor is provided, where a food product resting on a cutting bed is sliced with a cutting blade. The method is used for optimizing and monitoring the operation of the cutting blade. This is achieved in that a cutting force being applied by the cutting blade via the food product onto the cutting bed is determined using the sensor device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Patent Application No. 10 2012 024 947.0 filed on Dec. 19, 2012, which is hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The disclosure relates to a method for operating a food slicing device in which a sensor device with a sensor is provided. The cutting blade is used for slicing a food product resting on a cutting bed. 
       BACKGROUND 
       [0003]    DE 10 2009 011 860 discloses a cutting device comprising a detection device for detecting oscillations generated by the rotating blade. The detection device operates In particular with a structure-borne sound sensor which is attached in the region of a blade edge, or a support structure for said blade edge, respectively. 
         [0004]    Structure-borne sound sensors can be formed as oscillation speed sensors or as oscillation displacement sensors. Detecting a structure-borne sound is suitable for being able to adjust a cutting gap. 
         [0005]    However, this disclosure is not geared towards adjusting a cutting gap. It has the object to evaluate the cutting quality of the cutting blade and the cutting process in order to achieve optimization. 
       SUMMARY 
       [0006]    This object is satisfied according to the disclosure, in that a cutting force being applied by the cutting blade via the food product onto the cutting bed is determined using the sensor device. 
         [0007]    The sensor device is used, inter alia, for detecting blade wear. If a blade becomes blunt in the course of its use, then the cutting force increases, which can according to the disclosure be determined by the sensor device. 
         [0008]    Moreover, the disclosure can also aid in the selection of different cutting blades. Depending on the type, consistency and content of material to be cut, different cutting blades can be employed. The sensor device according to the disclosure can consequently be used to determine an optimal cutting blade. 
         [0009]    The same applies to determining the optimal blade rotation speed. Here as well, the sensor device according to the disclosure can be of good services. 
         [0010]    In addition, the disclosure can be used to identify process errors during slicing, or to determine deviations from operating parameters. 
         [0011]    The quality when slicing in particular food products also depends on ambient parameters, namely in particular, the temperature of the food product, the temperature of the processing room, and the humidity of both the product as well as the processing room. These parameters can be recorded with the aid of the sensor device according to the disclosure. 
         [0012]    Finally, it is also possible to determine the cutting quality of a cutting blade across its circumference. In particular, localized bluntness of the blade edge of a cutting blade can be determined. 
         [0013]    In an advantageous development of the disclosure, it is provided that the sharpness of the cutting blade can be calculated or derived, respectively, from the cutting force being determined by the sensor device This also applies to determining the blade geometry, this can as well be determined according to the disclosure. 
         [0014]    It is advantageous if the curve of the cutting force over time can be stored in an EDP-system of the sensor device. This EDP-system can subsequent be used for evaluation. 
         [0015]    Remaining service life of the cutting blade can advantageously also be determined in dependency of the determined cutting force with the aid of the disclosure. It is also conceivable to determine the remaining service life of the cutting blade in dependency of the curve of the determined cutting force over time. 
         [0016]    The sensor device can take into account product-specific data regarding the food product, and/or the temperature/humidity conditions of the material to be cut or of the processing room, and/or parameters of the cutting blade, respectively. 
         [0017]    At least one operating parameter of the slicing device can be set in dependency of the curve of the determined cutting force. This applies in particular to the position of the blade and/or the cutting bed, but also to the choice of cutting speed and/or the feed rate. 
         [0018]    Load spectrums can advantageously be determined in a computer-aided manner using peak loads and/or load profiles over time that are determined by the at least one sensor, which are used to determine values regarding the life span or maintenance intervals of wear and tear parts, in particular of bearings of shafts or parts of the drive. 
         [0019]    Based on the peak loads and/or load profiles over time, the method of linear damage accumulation can be used to obtain information on the life expectancy of components under stress. 
         [0020]    Linear damage accumulation takes into account that a component is normally subjected to not only an oscillating load with constant amplitudes, i.e., a rectangular load spectrum as used for example in the S-N fatigue test, but that the load intensity varies in it height. To calculate the life span, the amplitude spectrum is divided into individual rectangular spectra with a constant amplitude S_a and a partial number of fatigue cycles to failure n_i (stepped). According to the method of linear damage accumulation, a partial damage is now calculated for each partial spectrum in that the partial number of fatigue cycles to failure is divided by the maximum tolerable number of fatigue cycles to failure N_i at S_a of an S-N curve. The partial damages of all partial spectrums are added and deliver the total damage D of the component via D=SUM (n_i/N_i). If the damage exceeds the value 1, it is to be expected that the component will break or crack under the load spectrum examined. 
         [0021]    According to the linear damage accumulation, it is in particular irrelevant at which stress level a certain fraction of the maximum tolerable number of cycles to failure was spent. The damage to a partial spectrum I can be converted into that of a different partial spectrum j by dividing the respective partial numbers of cycles to failure n by the maximum tolerable numbers of cycles to failure N (n_i/N_i=n_j/N_j). 
         [0022]    If one imagines a two-stage stress, then it is according to the linear damage accumulation irrelevant in which sequence the stresses occur. Sequence effects can therefore not be explained. 
         [0023]    Using this method and corresponding data recording, life span can now be predicted for all machine components. It is thereby possible to take preventive influence on system availability of the food slicing device. This means higher availability and a higher degree of efficiency for the food slicing device. 
         [0024]    The sensor device can be provided, for example, at the cutting bed itself or its support. Furthermore, it is conceivable to arrange it at the blade head or its mounting support, respectively. It is also conceivable to provide a sensor at the cutting bed or its support, respectively, and at the blade head or it&#39;s mounting, respectively, and take a combined measurement. 
         [0025]    Strain gauges or piezoelectric crystal elements are possible sensors as pressure sensors, without the disclosure being restricted thereto, It is also conceivable to use other sensors, e.g. accelerometer sensors that are designed such that the force exerted by the cutting blade onto the food product is determined from the measured acceleration value using the known elasticities and masses of the food slicing device, It is therefore also conceivable to determine the sensor device in the direction of the forces applied in two linearly independent directions, for example, in a horizontal and a vertical direction. 
         [0026]    An embodiment of the disclosure is explained below using the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  schematically shows a front view of a first food slicing device; 
           [0028]      FIG. 2  shows a front view of a further embodiment of the disclosure, in which one or more sensors can be disposed between the support surfaces and the cutting bed; 
           [0029]      FIG. 3  shows a side view of a further embodiment of the disclosure, in which sensors are disposed in the region of the blade head, e.g. between the blade and the blade mounting; and 
           [0030]      FIG. 4  shows a side view of a further embodiment in which sensors are disposed between the blade mounting and a blade shaft. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    In the embodiment shown, the device  1  comprises a cutting bed  2  having a horizontal bearing surface  3  and a vertical side support  4 . Both are arranged at right angles to each other and, for example, integrally connected to each other. 
         [0032]    A food product  5 , presently a sausage with a circular cross section, rests on the bearing surface  3  and laterally contacts the support  4 , so that the sausage is positioned exactly in the corner between the bearing surface and the support. The connection between the bearing surface and the support can there be rounded. 
         [0033]    Below the cutting bed  2  is a cutting bed support  6  which serves as a mounting for the cutting bed. It can be fixed in a stationary manner. 
         [0034]    The cutting bed  2  is associated with a cutting blade  7  that rotates about an axis  8 . In the case illustrated, the cutting blade is a sickle blade, the blade edge of which at the perimeter comprises a varying distance to the cutting axis. During rotation of the cutting blade, the cutting blade penetrates into the material to be cut and with the blade edge crosses the entire cross-sectional area of the material to be cut, presently the food product  5 . In the case illustrated, the cutting blade rotates in a clockwise direction. 
         [0035]    The cutting blade  7  is positioned with its axis  8  such that the food product resting on the cutting bed is during the cutting process pressed into the angular arrangement of the cutting bed. 
         [0036]    To be able to sever slices in succession from the food product, the product is subjected to a certain feed motion feed which, for example, occurs continuously during cutting. This can be effected in that the food product  5  is conveyed in the forward direction on the cutting bed by a feed element  9 . 
         [0037]    The cutting blade is with its cutting plane positioned slightly in front of the cutting bed  2  so that it sweeps by the front side of the cutting sample [sic] during the cutting process and severs a slice from the food product  5 . 
         [0038]    Sensors  10  can be arranged in the cutting bed  2  to determine the cutting force of the cutting blade. These sensors can be disposed at appropriate locations of the cutting bed  2 , or the cutting bed support  6 , for example, in the area of the support  4 , the bearing surface  3  or—as already mentioned—on the support  6  for the cutting bed. Furthermore, it is conceivable to associate a plurality of sensors to the cutting blade  7  itself, for example, on the blade head, on the axis  8  at the drive shaft of the cutting blade, or at the mounting of the cutting blade. 
         [0039]    These sensors can be associated with an EDP-system  11  which comprises, for example, a memory and an evaluation unit. 
         [0040]    The sensor device  12  according to the disclosure can comprise one or more of the aforementioned sensors  10 . The position and the number of sensors  10  is determined by the desired recording quality and the optimum placement of these sensors. 
         [0041]    The sensor device is used to determine the cutting force being applied during the slicing of the food product by the cutting blade  7  via the food product  5  onto the cutting bed  2 . By determining the cutting force, conclusions can be drawn regarding the sharpness of the cutting blade. This is done by comparison of reference data that are determined, for example, by empirical tests. Possible blade wear, which can also be given across only part of the blade perimeter, can thereby be determined. 
         [0042]    Furthermore, determination of the cutting force can serve to perform a selection among different cutting blades, namely in regard to the material itself to be cut. The latter will usually vary greatly, depending on whether it is meat, sausage, cheese or other material to be cut. The consistency and the internal structure of the material to be cut are also decisive for the quality of the slicing. The optimum blade speed can likewise be determined. The EDP-system of the sensor device can be used for illustrating the curve of the cutting force over time, and to draw conclusions therefrom for the optimal design of the blade, its rotational speed, the remaining service life in dependency of the wear already experienced etc. 
         [0043]    Since the EDP-system creates the possibility to store and evaluate the cutting performance over time, process errors during slicing and deviations from operating parameters can also be recorded. 
         [0044]    Furthermore, it is possible to determine the influences of ambient conditions during slicing, such as moisture, temperature and elasticity of the material to be cut and the room conditions of the processing room. 
         [0045]    The forces measured during the cutting process by the sensor device can also during operation of the device serve to adjust operating parameters, meaning to reset them. This pertains in particular to the position of the cutting blade relative to the food product, or the cutting bed, respectively. This additionally pertains, for example, to the position of the food product on the cutting bed. This can furthermore pertain to the cutting speed of the cutting blade, the rotational speed thereof, and to the feed motion. 
         [0046]    In the drawing, for example, forces F 1 , F 2  and F M  are shown. F 1  represents the horizontal force that is detected by the sensor located in support  4 . F 2  determines, for example, the vertical force F 2  arising in support  6 . The same applies to the sensor  10  that is arranged below the bearing surface  3 . It also determines vertical forces F 3 . 
         [0047]    Force F M  symbolizes the force which is determined by the blade head during the cutting operation. It provides a counterforce to the force acting upon the cutting bed. 
         [0048]    Strain gauges can for instance be used as sensors. Accelerometer sensors are also conceivable which determine the force being exerted by the cutting blade  7  onto the food product  5  from the measured acceleration value using the known elasticities and masses of the food slicing device. 
         [0049]    In addition, pressure or force sensors are conceivable that transform the signals detected into electric values and forward them. 
         [0050]    These sensors can use physical capacitive or piezoelectric effects. 
         [0051]    In the embodiment of  FIG. 2 , sensors, for example, force or pressure sensors can be disposed between the cutting bed and  2  and the support surfaces  13 . They can be associated with the cutting bed and also be oriented e.g. horizontally or also vertically. 
         [0052]    In the embodiment of  FIG. 3 , the food product is located between two conveyor belts  5  that together form the feed element  9 . Upstream of this element is the cutting bed  2 . Between it and a support surface  13 , a sensor  10  is arranged which, for example, records the vertical forces. 
         [0053]    Alternatively or cumulatively, respectively, it is also possible to arrange at least one sensor in the blade mounting itself, as can be seen from the partial sectional view of the blade. The sensors can, for example, be arranged at the front end of the axis  8  associated with the cutting blade. 
         [0054]    It is also conceivable to accommodate them within the mounting assembly  14 . 
         [0055]      FIG. 4  shows a similar solution. The cutting blade  7  comprises a blade mounting  15 . Sensors  10  can also be disposed between the latter and the blade shaft  8 .