METHOD FOR DETERMINING THE GRINDING REQUIREMENTS OF CHOP KNIVES OF A CHOPPERING DEVICE

Description

[0001] The present invention relates to a method for determining the grinding requirement of chopping knives of a chopping device according to the preamble of claim 1. Furthermore, the invention relates to a self-propelled forage harvester according to the preamble of claim 15.

[0002] A method for determining the grinding requirement of chopping knives of a chopping device of a self-propelled forage harvester, wherein a wear condition is cyclically determined by a monitoring device, and a self-propelled forage harvester of the type mentioned above are known from the prior art.

[0003] EP 2 008 508 B1 describes a forage harvester equipped with a camera for generating images of the cutting edges of the chopping knives. The images are displayed on a monitor in the operator's cab of the forage harvester and evaluated by an operator with regard to the quality of the cutting edges. Based on irregularities in the cutting edge, the operator determines whether further sharpening is necessary to achieve the desired cutting edge sharpness.

[0004] From EP 2 225 931 B1 a forage harvester and a method for determining the grinding requirements of chopping knives are known, according to which a prediction of the expected wear pattern is derived on the basis of crop parameters, such as crop type and machine parameters, such as crop throughput and cutting length.

[0005] EP 3 738 429 A1 relates to a driver assistance system for a forage harvester, in which a monitoring device determines the wear condition of the chopping knives and the distance between the chopping knives and the counter blade by means of a target / actual comparison. Based on the determined wear condition or the determined distance between the chopping knives and the counter blade, a prediction of the wear condition of the chopping knives or a prediction of the condition of the counter blade is generated, which forms the basis for the automatic estimation of the time to perform a sharpening operation. The number of sharpening cycles to be performed is also predicted in order to then predict a suitable time so as not to interrupt the ongoing harvesting process.The driver assistance system informs the operator via a display that one or more chopping blades have fallen below a threshold for cutting sharpness. The operator then decides when the chopping blades should be sharpened. DE 103 57 177 A1 and DE 10 2019 112965 A1, however, disclose methods for determining the sharpening requirements of chopping blades.

[0006] The aforementioned prior art has in common that the operator is informed when a critical wear condition is reached; however, due to the lack of a suitable benchmark, the operator remains unclear about the specific scope of the grinding process to be carried out. Based on the aforementioned prior art, the invention aims to further develop a method for determining the grinding requirements of chopping knives in a chopping device, as well as a self-propelled forage harvester, in such a way that the operator is informed about the current wear condition and the resulting effort required for a grinding process in a more comprehensible manner, enabling them to react more flexibly.

[0007] From a process engineering perspective, this problem is solved starting from the preamble of claim 1 in conjunction with its characterizing features. From an apparatus engineering perspective, the problem is solved starting from the preamble of dependent claim 15 in conjunction with its characterizing features. The subsequent dependent claims each represent advantageous embodiments of the invention.

[0008] According to claim 1, a method for determining the grinding requirement of chopping knives of a chopping unit of a self-propelled forage harvester is proposed, wherein a wear state is cyclically determined by a monitoring device. According to the invention, the monitoring device comprises an input / output unit by means of which a target state of the chopping knives to be produced by a grinding device is entered or selected as a target specification, and that, depending on the target state and the determined wear state, the monitoring device continuously generates information and visualizes by the input / output unit the extent to which the currently determined wear state deviates from the target state.The method according to the invention enables an operator to specify a target state by input or selection, which corresponds to the requirements for the, in particular, optimal condition of the chopping knives in a given harvesting situation. Depending on the target state and the specified wear condition, the monitoring device then continuously generates information and visualizes, via the input / output unit, the extent to which the currently determined wear condition of the chopping knives, hereinafter also referred to as the actual state, deviates from the target state. The operator is thus kept constantly informed of the deviation through cyclical monitoring. Furthermore, unlike the prior art, the operator does not need to subjectively assess the actual state of the chopping knives.This makes it easier for the operator to determine the current grinding requirements in order to better plan the execution of grinding operations, for example when changing fields, during waiting times, refueling stops and the like.

[0009] In particular, a target cutting edge and / or a number of grinding cycles to be performed can be entered or selected as the desired state of the shredding blades, after which the entered or selected cutting edge is achieved. The cutting edge can be entered or selected as an absolute or relative value. Preferably, the target cutting edge of the shredding blades can be specified as a percentage of the cutting edge of a new shredding blade. Alternatively or additionally, the operator can specify a number of grinding cycles to be performed by the grinding device until the shredding blades have regained the entered or selected target state.

[0010] Preferably, the degree of deviation of the currently determined wear state from the entered or selected target state can be visualized as an operating parameter of the grinding device. In this way, the operator is continuously informed about the wear state or actual condition of the shredder blades. In particular, displaying an operating parameter of the grinding device as an indicator of the deviation is more readily understandable for the operator, as these are generally familiar values ​​that allow the operator to better assess the duration and necessity of initiating a resharpening process.

[0011] According to a preferred training method, the input / output unit can display at least one reference value for the target state to be entered or selected. This reference value can serve as a guideline or orientation aid. Especially for inexperienced operators, providing this reference value can be a useful aid during the operation of the forage harvester. The reference value can incorporate both manufacturer-specific knowledge and experience-based knowledge.

[0012] As a comparative parameter, the relative and / or absolute cutting sharpness of new chopping knives and / or a target value adapted and optimized for a specific harvesting situation can be displayed for selection. The relative and / or absolute cutting sharpness as a comparative parameter can be determined, in particular, through a dialog-based query of the harvesting situation. The operator can, for example, specify the type of crop being harvested. Depending on the crop type, for example, when chopping corn or grass, different levels of wear on the chopping knives are tolerated, so the optimized target value is different, and especially higher, for corn than for grass. It is also conceivable to additionally query further boundary conditions that influence the wear of the chopping knives. For example, one boundary condition could be harvesting under sandy conditions.Based on the type of crop and additional boundary conditions determined by querying certain parameters, a value for the relative cutting sharpness can be retrieved from a database stored in a memory unit of the monitoring device and displayed as a suggestion for the comparison value.

[0013] According to a preferred embodiment, the number of grinding cycles to be performed by the grinding device to achieve the entered or selected target condition can be used as a measure of deviation. Preferably, the operating parameter of the grinding device displays the number of grinding cycles by which the currently determined wear condition (actual state) differs from the entered or selected target condition. The displayed value can be a positive or negative number of grinding cycles, describing the difference between the current actual state and the selected or entered target condition. Thus, a positive number of grinding cycles represents an actual state of the shredding blades that is better than the selected or entered target condition.Accordingly, a negative number of grinding cycles for a current actual state of the shredding knives represents the deviation from the target state, which also corresponds to the number of grinding cycles to be performed, after which the target state of the shredding knives selected or entered by the operator is achieved.

[0014] In particular, displaying the number or amount of grinding cycles as an order of magnitude of the deviation is more tangible for the operator, as it is a parameter familiar to the operator, enabling them to better assess the duration and necessity of initiating a regrinding process.

[0015] In particular, the input / output unit can display comparison images of the wear condition of one or more chopping knives, showing the currently measured wear condition and a corresponding wear condition with the target condition. In addition to displaying the deviation as the number or amount of grinding cycles required, the operator can also see the actual condition of the chopping knives and compare it to the target condition. The operator does not need to leave the forage harvester's cab for this. The operator can also be shown only a single knife or several selected knives, indicating which ones are partially or completely damaged. This can be useful, for example, if individual knives have been damaged by foreign objects. The operator can then decide whether to replace the damaged knives.Particularly preferred, several comparison images can be displayed side by side or one above the other by the input / output unit, showing the new state of shredding blades and / or the set or selected target state and / or another cutting sharpness-specific reference value and / or the current actual state.

[0016] In this process, the comparison images representing the target state can be selected from a database stored in a memory unit of the monitoring device, depending on a specification for harvesting parameters and / or machine parameters.

[0017] Furthermore, comparative images depicting the currently determined wear state can be captured by an optical detection device, which can be specifically assigned to the grinding device. Assigning it to the grinding device is advantageous because the optical detection device is less exposed to the crop flow.

[0018] Furthermore, the input / output unit can include a touchscreen, which switches between windowed and full-screen modes when a comparison image is selected by touch. This allows for better visibility of details in the comparison images due to the magnified display in full-screen mode.

[0019] According to a preferred further development approach, a virtual control panel can be displayed by the input / output unit, allowing manual selection of the desired state. This could, for example, be a control panel implemented as a push button, which selects and sets a default state from those stored in the database. These default states could be manufacturer-specific.

[0020] In particular, the input / output unit can display a virtual control element that allows for manual selection of the desired state. This virtual control element can be a movable or rotatable control that the operator uses to input a specific desired state.

[0021] Preferably, the information visualized by the input / output unit can be displayed as a numerical value, a bar graph, and / or a time series. Preferably, the information is displayed as a numerical value in a display field by the input / output unit.

[0022] According to one embodiment, an authorization query can be performed before an input is implemented or a target state is selected. This makes it possible to handle the setting restrictively, so that individual operators or definable groups of people can be excluded from selecting or entering a target state, or at least have their input restricted.

[0023] According to a further teaching as defined in claim 15, which has independent significance, a self-propelled forage harvester for use in a proposed method is claimed. Reference may be made to all embodiments suitable for describing the self-propelled forage harvester as such or its use.

[0024] The present invention is explained in more detail below with reference to an embodiment illustrated in the drawings.

[0025] They show: Fig. 1 a schematic representation of a forage harvester; Fig. 2 a detailed view of the forage harvester according to Fig. 1 ; Fig. 3 a schematic representation of a monitoring device of the forage harvester; and Fig. 4 a schematic representation of an operator display of an input / output unit of the forage harvester.

[0026] Figure 1Figure 1 schematically shows a forage harvester 1 with a driver's cab 2, which accommodates a harvesting head 3, for example, a corn header, at its front. At the rear of the harvesting head 3 are so-called intake and pre-compression rollers 4, which receive a crop flow 5 from the harvesting head 2, compact it, and transfer it to a chopping unit 6 at their rear. The chopping unit 6 comprises a chopping drum 7, which is equipped with chopping knives 8 of a chopping knife assembly 9. The rotating chopping knives 8 pass a counter blade 11 in the intake area 10 of the chopping drum 7, over which the crop flow 5 to be chopped is conveyed.In the rear section of the chopping drum 7, the shredded crop 5 is then transferred either to a secondary shredding unit 13, designed as a so-called cracker 12, or directly to a secondary acceleration unit 14. While the secondary shredding unit 13 further reduces the granular components of the crop flow 5, such as corn kernels, the secondary acceleration unit 14 accelerates the crop flow 5 in such a way that it is moved through a discharge spout 15 and exits the forage harvester 2 at its end in the area of ​​a discharge flap 16, where it can be transferred to a transport vehicle (not shown). Furthermore, a grinding device 17, which is known per se and therefore not described in detail here, is associated with the circumference of the chopping drum 7. The grinding stone 18 of this device is moved horizontally across the width of the chopping drum 7 to sharpen each chopping knife 8 positioned around the circumference of the chopping drum 7.For the purpose of activating or deactivating the knife sharpening process, an input / output unit 19 is assigned to the sharpening device 17.

[0027] According to Figure 2 The chopping knife arrangement 9 comprises right- and left-hand chopping knife arrangements 9a, 9b, each chopping knife arrangement 9a, 9b comprising a plurality of chopping knives 8 positioned obliquely to the axis of rotation 20 of the chopping drum 7 around its circumference. The chopping drum 7 is enclosed at the bottom by a drum base 21. At the top, the chopping drum 7 is enclosed by a drum rear wall 22. The sensor arrangement 23 can be configured according to the Figure 2In the illustrated embodiment, the sensor arrangement 23 can be positioned either on the rear wall 22 of the drum or on the drum base 21. It is also conceivable that a sensor arrangement 23 is arranged on both the drum base 21 and the rear wall 22 of the drum simultaneously. Depending on the positioning of the sensor arrangement 23, the drum base 21 and / or the rear wall 22 of the drum can preferably be made of stainless steel. Regardless of the specific positioning, at least two sensor arrangements 23a, 23b are assigned to each chopping drum 7 such that one of the sensor arrangements 23a, 23b is assigned to each corresponding chopping knife arrangement 9a, 9b, with each sensor arrangement 23a, 23b completely covering the cutting edge 24 of the respective chopping knife 8, so that each cutting edge 24 can be detected along its entire length by the respective sensor arrangement 23a, 23b.Furthermore, it is within the scope of the invention that the respective sensor arrangement 23a, 23b is positioned either parallel to the axis of rotation 20 of the chopping drum 7 or parallel to the cutting edge 24 of the chopping blades 8 on the drum base 21 and / or the drum rear wall 22. The lower right illustration in . Figure 2The figure shows only an example of the possible orientations of the sensor arrangements 23a, 23b in a single illustration. Preferably, all sensor arrangements 23a, 23b are positioned either parallel to the axis of rotation 20 of the chopping drum 7 or parallel to the cutting edge 24 of the chopping blades 8. In the illustrated embodiment, the sensor arrangements 23a, 23b are designed as induction sensors 25, each sensor arrangement 23 comprising one or more magnetic excitation arrangements 26 and a pole arrangement 27 interacting with them. Further details of the sensor arrangements for detecting the wear condition of the chopping blades 8 are given in EP 3 363 281 A1, to whose disclosure content reference is hereby made in full.

[0028] In Fig. 3A monitoring device 29, which serves to control the grinding device 17, is shown schematically. The monitoring device 29 is connected to the grinding device 17, the input / output unit 19, and the sensor arrangements 23a and 23b via signal transmission. The monitoring device 29 comprises a processing unit 30 and a storage unit 31. A database can be stored in the storage unit 31, among other things. The monitoring device 29 serves to evaluate the signals provided by the sensor arrangements 23a and 23b, from which the current wear state of the chopping blades 8 is cyclically determined. A target state of the chopping blades 8, to be produced by the grinding device 17, is entered or selected as a target specification via the input / output unit 19 of the monitoring device 29.The field chopper 1 can also include a higher-level control device 28, which serves to control the working elements of the field chopper 1.

[0029] The representation in Fig. 4 Figure 1 shows a schematic representation of an operating display for the input / output unit 19 of the forage harvester 1. The input / output unit 19 comprises a screen 32, which is touch-sensitive. The display shown on the screen 32 illustrates an example of a setting situation in which an operator 33, symbolically represented by a hand, can input, i.e., specify, or select a target state for the cutting sharpness of the chopping knives 8 to be produced by the grinding device 17. The operator 33 has several options for this, which are explained below.

[0030] In an operating situation where the operator 33 is unsure which target state to specify, it is possible to select a manufacturer-defined value for a target state by activating a virtual control panel 34. Manufacturer-defined target state values ​​for different crop parameters and operating parameters, such as crop type, harvesting region, and / or machine type, can be stored and retrieved in the memory unit.

[0031] A scale 35 indicates the relative cutting sharpness of the chopping blades 8. This scale ranges from 0% to 100%. Alternatively or additionally, an absolute value for the cutting sharpness of the chopping blades 8 can also be displayed. According to a preferred embodiment, the input / output unit 19 can display at least one comparative value for the target state to be entered or selected. This comparative value can serve as a guideline or orientation aid. The relative cutting sharpness of the chopping blades 8 when new and / or a target state value adapted and optimized for a specific harvesting situation can be displayed as a comparative value. Additionally, to assist the operator 33 with selection or input, several comparison images 36, 37, 38 can optionally be displayed, each corresponding to different values ​​on the scale 35 for the relative cutting sharpness.

[0032] Comparison image 36 shows a chopping blade 8 in its new condition with a relative cutting sharpness of 100%. The following comparison image 37 shows a chopping blade 8 that already exhibits significant wear and whose relative cutting sharpness is between 50% and 75%. The third comparison image 38 shows an example of a chopping blade 8 which, due to advanced wear, negatively impacts the efficiency of the chopping process. In particular, the power requirement of the chopping device increases. The achievable chopping quality of the harvested material is also affected. To enlarge any of the comparison images 36, 37, or 38, the display can be switched from windowed mode to full-screen mode or vice versa by touching the respective image.

[0033] In particular, the input / output unit 19 can display comparison images of the wear condition of the chopping knives 8, showing the currently determined wear condition and a wear condition corresponding to the target condition. In addition to displaying the deviation, the actual condition of the chopping knives 8 can thus also be displayed to the operator 33. For this purpose, the operator 33 does not need to leave the driver's cab 2 of the forage harvester 1. Preferably, several comparison images 36, 37, 38 can be displayed side by side or one above the other by the input / output unit 19, showing the new condition of chopping knives, the set or selected target condition or another cutting sharpness-specific reference value and / or the current actual condition.

[0034] Furthermore, comparison images depicting the current wear state determined by the monitoring device 29 can be captured by an optical detection device (not shown), which may be associated with the grinding device 17. Assigning it to the grinding device 17 is advantageous because the optical detection device is less exposed to the crop flow 5. These comparison images, which depict the current wear state, can be displayed, for example, in conjunction with a generated warning message. Additionally or alternatively, the operator 33 can retrieve these comparison images independently. For this purpose, a virtual control element 43 labeled "Retrieve current comparison images" can be displayed, for example, to show a comparison image corresponding to the current state of the chopping knives 8.

[0035] When the virtual control panel 34 is activated by the operator 33, a specific value for a target state is specified, particularly for the type of crop to be processed.

[0036] To determine the type of crop to be processed, and possibly other crop and operating parameters, in advance, a dialog-based query can be performed. The operator 33 can, for example, specify the crop type. It is also conceivable to query additional boundary conditions that influence the wear of the chopping knives. For example, one boundary condition could be harvesting under sandy conditions. Based on the crop type, a value for the relative cutting sharpness can be retrieved from the database stored in the memory unit 30 of the monitoring device 29. At least some of the crop and operating parameters can be determined automatically by additional sensor devices already present on the forage harvester 1, such as a position sensor or a front-facing camera.

[0037] After activating the virtual control panel 34 to select the target state, exactly one indicator 39 or 40 is displayed next to the scale 35. In the example case of the crop type "corn", indicator 39 is displayed, and in the example case of the crop type "grass", indicator 40 is displayed.

[0038] If the operator 33 chooses to manually enter the target state, the input / output unit displays a virtual control element 41, which allows manual selection of the target state. This virtual control element 41 can be designed as a movable or rotatable control. In the illustrated embodiment, the virtual control element 41 is designed as an arrow that can be virtually moved along the scale 35.

[0039] Depending on the procedure used by the operator 33, whether to manually enter the target state using the control element 41 or to select it by operating the control panel 34, only one indicator 39 or 40 or the control panel 34 is displayed, which shows the entered or selected target state.

[0040] The monitoring device 29 continuously generates information based on the target state and the determined wear state, and the input / output unit 19 visualizes the extent to which the currently determined wear state deviates from the target state. As previously explained, the target state of the shredding blade 8 is defined as a relative cutting edge and / or a number of grinding cycles to be performed, after which the target relative cutting edge is achieved. The degree of deviation from the current wear state to the entered or selected target state is visualized as an operating parameter of the grinding device 17. Preferably, the operating parameter of the grinding device 17 is the number of grinding cycles by which the actual state differs from the target state.The deviation is measured by the number of grinding cycles to be performed by the grinding device 17 to achieve the entered or selected target state.

[0041] Preferably, the information visualized by the input / output unit 19 can be displayed as a numerical value, as a column and / or as a time series in a separate display field 42.

[0042] In the simplest case, the input / output unit 19 displays exactly one numerical value in the display field 42 for the number of grinding cycles, which represents the deviation of the current actual state of the shredding blades 8 from the target state. Displaying the number of grinding cycles as a purely numerical value has the advantage that this is a familiar benchmark for comparison for the operator 33.

[0043] The value displayed in display field 42 can represent a positive or negative number of cutting cycles, describing the difference between the current actual state and the selected or entered target state. A positive number of grinding cycles indicates that the actual state of the shredding blades 8 is better than the selected or entered target state. Conversely, a negative number of grinding cycles indicates the deviation from the target state for the current actual state of the shredding blades 8, and also corresponds to the number of grinding cycles required before the operator achieves the target state of the shredding blades 8 as selected or entered.

[0044] For example, the value "0" for the number of cutting cycles in display field 42 indicates to operator 33 that the target state has been reached or still exists.

[0045] A negative value "-10" for the number of grinding cycles indicates that the actual state of the chopping blades 8 is ten grinding cycles away from the target state, i.e., that the deviation is ten grinding cycles to be performed in order to restore the target state of the chopping blades 8.

[0046] A negative value "-27" for the number of grinding cycles as a deviation indicates that the actual state of the shredding blades is 8 twenty-seven grinding cycles away from the target state.

[0047] A positive value "+5" for the number of grinding cycles as a deviation indicates that the actual state of the shredding blades 8 is five grinding cycles away from the target state, where the positive number of grinding cycles indicates that the current actual state of the shredding blades 8 is five grinding cycles better than the target state.

[0048] The operator 33 can use input / output unit 19 to enter a target value for the number of grinding cycles required to achieve the selected or set target state. For example, if the target value for the number of grinding cycles is entered as "20", the operator 33 will be notified by a warning message generated by the monitoring device 29 that the actual state of the shredding blades 8 corresponds to a deviation of "-20".

[0049] According to an example illustrating the functional sequence, operator 33 specifies a target cutting sharpness of 80% for the shredding blades 8. Furthermore, operator 33 specifies the target value "30" for the number of grinding cycles required to achieve this target state.

[0050] During the shredding process, the value "-23" is displayed in display field 42 as the deviation of the actual state from the target state. This deviation is below the target value for the number of grinding cycles to be performed. If an interruption occurs in this situation, for example due to a disruption in transport logistics, the operator 33 can initiate the twenty-three grinding cycles to restore the target state of the shredding knives 8, even though the target value of "-30" has not yet been reached. The amount of the deviation displayed in display field 42 as the number of grinding cycles is then "0". The shredding process can then continue.

[0051] However, the operator can deviate from the procedure described above and initiate thirty grinding operations, resulting in an actual state for the cutting sharpness of the shredding knives 8 that is above the target state. This is illustrated to the operator by the fact that the amount of the deviation displayed in display field 42, as the number of grinding cycles, is then "+7".

[0052] For example, if the operator completes only 20 grinding cycles instead of the required 23, the target state will not be reached. The resulting deviation from the actual state is displayed in display field 42 as "-3" as the deviation in the number of grinding cycles. The shredding process can still be continued, but already with a deviation of three grinding cycles from the target state.

[0053] If, during the chopping process, the value "-30" is displayed in display field 42 as a deviation for the number of grinding cycles, the operator 33 can be alerted by a warning message that the set deviation of the actual state from the target state has been reached. Regardless of the warning message, the operator 33 can continue the chopping process, for example, if the completion of the current harvesting process is imminent. Accordingly, a higher deviation will be displayed at the end of the harvesting process; for example, the field will show "-40" as the number of grinding cycles required to return to the set target state from the current wear level. Reference symbol list

[0054] 1 Forage harvester 30 computing unit 2 Driver's cab 31 Storage unit 3 Harvesting attachment 32 Screen 4 Feed and pre-compression rollers 33 Operator 5 Harvested crop power 34 control panel 6 shredding device 35 scale 7 Shredding drum 36 Comparison image 8 shredder blade 37 Comparison image 9 Shredding blade arrangement 38 Comparison image 9a right-side shredding blade arrangement 39 indicator 9b left-side shredding blade arrangement 40 indicator 10 catchment area 41 Control element 11 counter blade 42 Display field 12 cracker 43 Control element 13 Post-shredding unit 14 Post-acceleration device 15 Ejection manifold 16 Ejection flap 17 Grinding device 18 whetstone 19 Input-Output Unit 20 axis of rotation 21 drum bottom 22 Drum back wall 23 Sensor arrangement 23a Sensor arrangement 23b Sensor arrangement 24 Cutting edge 25 Induction sensor 26 Pathogen arrangement 27 Pole arrangement 28 Control device 29 Monitoring device

Claims

1. A method for determining the need for sharpening chopping blades (8) of a chopping device (6) of a self-propelled forage harvester (1), wherein a state of wear is cyclically determined by a monitoring device (29), characterized in that the monitoring device (29) comprises an input / output unit (19) by means of which a target state of the chopping blades (8) to be established by a sharpening device (17) is input or selected as a target specification, and in that information is continuously generated by the monitoring device (29) as a function of the target state and the determined state of wear and the extent to which the current determined state of wear deviates from the target state is visualized by the input / output unit (19).

2. The method according to claim 1, characterized in that a cutting sharpness is input or selected as the target state of the chopping blades (8) and / or a number of sharpening cycles to be executed, after the execution of which an input or selected cutting sharpness is obtained, is input or selected as the target state of the chopping blades (8).

3. The method according to claim 1 or claim 2, characterized in that the extent of the deviation of the current state of wear from the input or selected target state is visualized as an operating parameter of the sharpening device (17).

4. The method according to claim 1 to 3, characterized in that at least one comparative value for the target state to be input or selected is displayed by the input / output unit (19).

5. The method according to claim 4, characterized in that the cutting sharpness in the new state of chopping blades (8) and / or a target state value which is adapted and optimized to a specific harvesting situation is displayed as a comparative value.

6. The method according to one of claims 3 to 5, characterized in that a number of sharpening cycles to be executed by the sharpening device (17) in order to obtain the input or selected target state is used as a measure of the deviation.

7. The method according to one of the preceding claims, characterized in that comparative images (36, 37, 38) for the state of wear of the chopping blades (8) are displayed by the input / output unit (19), the comparative images representing the current determined state of wear and a state of wear corresponding to the target state.

8. The method according to claim 7, characterized in that, for the display of the comparative images (36, 37, 38) representing the target state, these are selected as a function of a specification for harvesting parameters and / or machine parameters from a database stored in a memory unit (31) of the monitoring device (29).

9. The method according to claim 7 or claim 8, characterized in that comparative images which represent the current determined state of wear are recorded by an optical detection device, which in particular is associated with the sharpening device (17).

10. The method according to one of claims 6 to 9, characterized in that the input / output unit (19) comprises a touch-sensitive display screen (32), and in that when a comparative image (36, 37, 38) is selected by touch, the depiction switches from a window mode to a full-screen mode or vice versa.

11. The method according to one of the preceding claims, characterized in that a virtual control panel (34) is displayed by the input / output unit (19), with which virtual control panel a manual selection of the target state is made.

12. The method according to one of the preceding claims, characterized in that a virtual control panel (41) is displayed by the input / output unit, with which virtual control panel a manual input of the target state is made.

13. The method according to one of the preceding claims, characterized in that the information visualized by the input / output unit (19) is depicted as a numerical value, as a bar and / or as a chronological sequence.

14. The method according to one of the preceding claims, characterized in that an authorization enquiry is made before the implementation of an input or selection of the target state.

15. A self-propelled forage harvester with at least one chopping device (6) comprising a plurality of chopping blades (8), wherein the forage harvester (1) is designed for use in a method according to one of the preceding claims.