Method for Operating a Ground Milling Machine

This application claims the benefit of German Patent Application No. DE 10 2021 117 493.7, filed Jul. 7, 2021, and which is hereby incorporated by reference.

The invention relates to a method for operating a ground milling machine, in particular a road milling machine, a stabilizer, a recycler, a surface miner or the like, having an interchangeable milling drum, wherein the milling drum is equipped with a plurality of milling tools, in particular round shank picks, wherein the milling drum has a current state, wherein a control unit is provided for controlling at least one function of the ground milling machine, and wherein the milling drum has a characteristic feature or a characteristic feature is assigned to the milling drum.

A road milling machine having a milling drum is known from German patent reference DE 10 2016 113 251. The milling drum is equipped with a characteristic feature. A suitable reader can be used to read this characteristic feature. The characteristic feature is evaluated in a control unit and then the road milling machine recognizes which type of milling drum it is. Different types of milling drums are designed to perform different work tasks. A so-called fine milling drum is used to remove the upper part of the surface course of a road pavement by milling. In particular, slight irregularities in the road surface can be removed. The resulting surface course can be immediately opened for the use of road traffic. Another type of milling drum is used to remove a complete road surface. Furthermore, special milling drum types are designed for different work tasks, e.g., with regard to working width, milling depth or desired milling texture.

After the road milling machine has automatically recognized the milling drum type based on the characteristic feature of the milling drum, the control unit can preset a suitable machine parameter set. This machine parameter set can be used to operate the road milling machine in a suitable manner.

Another German reference DE 10 2015 111 249 A1 discloses a road milling machine in which preset machine parameters, material properties of the substrate to be milled and job data can be entered. Using characteristic diagrams, suitable target machine parameters can be computed from these default values. The target machine parameters can be displayed to the machine operator who can then decide whether to set these target machine parameters at the milling machine. Alternatively, the target machine parameters can be automatically transferred to a control unit for controlling the road milling machine.

Additional documents EP 2 716 816 A1 and EP 3 260 603 A1 disclose road milling machines having a sensor system. The sensor system can be used to record the volume milled by a road milling machine.

Finally, road milling machines having detection devices are known. These detection devices can be used to automatically determine the wear of the milling tools.

The milling machines described above facilitate completing the upcoming milling task for the machine operator. After the milling task is completed, the milling machine is transported to the next job site, where the installed milling drum type can be used to complete the set requirements.

If the milling drum is in a partially worn state, it can continue to be used. If the milling tools are completely worn, the milling tools have to be replaced. After the replacement, the milling machine can then continue to be operated at the construction site.

The present invention addresses the problem of providing a method for operating a ground milling machine, which can be used to optimize the planning and execution of upcoming milling tasks.

This problem is solved by at least one data set containing information on the current state of the milling drum being stored in a storage unit, by a characteristic feature identifying the milling drum being assigned to the data set in the storage unit, and by transmitting this data set to a processing device.

According to the invention, the state of the milling drum is stored. This state can be detected directly, for instance, by measuring the milling drum. For instance, an optical measurement method can be used for this purpose, which, for instance, uses a laser scanner to measure the milling tools and compares the result to a measurement result of the milling drum in the unworn state.

Preferably, however, the state is determined indirectly, for instance using job data and/or material characteristics of the material removed and/or the set machine parameters that were recorded or taken into account during the tool insertion of the milling tools.

Material parameters in the context of the invention can be the abrasiveness and/or the hardness and/or a material type (for instance asphalt or concrete) and/or a material composition and/or a temperature and/or a layer structure of the surface to be removed.

The current state can also be entered manually. In particular, it is conceivable to manually set an initial state and then update it automatically during operation.

For instance, provision may be made that the existing picks of a milling drum are replaced with new or partially worn picks. The operator of the ground milling machine can then manually enter the current state of these picks and in that way manually set the initial state. During operation, this state is then updated automatically, as described above.

Job data are, in particular, data that have been or will be recorded during the operation of the milling drum, for instance the milled surface, the milling volume and/or the milled mass of the material removed and/or the milling duration.

Feasible set machine parameters in the context of the invention are machine parameters that are or have been set to be defined or variable during a working operation of the milling drum, for instance, the milling depth, the feed rate, the milling drum speed, the motor power transmitted to the milling drum and/or the torque transmitted to the milling drum. One or more of these machine parameters can be part of a machine parameter set.

The current state of the milling drum may include and/or comprise one or more of the wear components listed below:

The current state of the milling drum can be determined solely by one of the aforementioned wear components and stored in the data set.

However, as mentioned above, in the context of the invention, the current state of the milling drum can also be characterized by a tuple comprising at least two of the aforementioned wear components and these are taken into account in the data set.

If several wear components are considered in a data set, it is particularly conceivable that depending on the type of milling drum, one wear type can be dominant and is assessed accordingly in the data set, or that a combination of wear types is considered and/or only the most heavily worn components have to be considered.

The current state of the milling drum can also be taken into account as at least one key figure in the data set, wherein the key figure contains, for instance, information on the remaining useful life of the milling drum or which can be derived from the remaining useful life of the milling drum. It is also conceivable that the key figure indicates a residual wear capacity.

The key figures can represent the current state of the milling drum and in that way permit conclusions to be drawn concerning the work results that can be achieved using the milling drum and/or the work output that can still be achieved by the milling drum.

The current state of the milling drum may also include a qualitative assessment. In particular, it can be indicated accordingly whether the milling drum is still basically usable. The qualitative classification can also take into account the efficiency of the milling drum in completing a milling task or the quality of the work result that can be produced by the milling drum, for instance in the form of a percentage. It is also conceivable to take a large number of key figures for individual milling drum components into account in the data set.

A single key figure and/or a qualitative assessment can also be derived as an “overall state of wear” from the overall consideration of a large number of key figures.

After the state of the milling drum has been detected, a data set according to the invention is formed that reflects the current state of the milling drum. In the storage unit this data set is linked to the characteristic feature individualizing the milling drum. In other words, the characteristic feature is a unique identifier of an individual milling drum. The data set can then be transferred to a processing device. For this purpose, the processing device can be arranged at the ground milling machine, for instance. It is also conceivable to spatially separate the processing device from the ground milling machine. For instance, it is conceivable that the processing device is at least temporarily in wired or wireless communication with the ground milling machine.

An additional processing device may also be provided.

The further processing device and the processing device may be combined into a joint unit, or provision may preferably be made that the processing device and the further processing device are spatially separated from each other.

The data set can be evaluated in the further processing device. Using the characteristic feature of the milling drum, which can be used to uniquely identify the milling drum and from which the type of milling drum can be derived, a computation unit determines whether this milling drum is generally suitable for an upcoming milling task. Then, in the further processing device, the determination can be made whether this milling drum, which is generally suitable, meets certain requirements wherein the current state results from the data set.

Within the scope of the invention, the milling drum which is actually best suited for the upcoming task can also be selected in the further processing device from a pool of milling drums, which are generally suitable according to their milling drum type for performing the upcoming milling task.

The suitability of the milling drum can be determined by considering the current state of the pool's milling drums. As a criterion, it can be specified, for instance, that the individually most suitable milling drum is filtered out of the pool, for instance using the further processing device, which can be used to perform the upcoming task most quickly, efficiently, or cost-effectively.

It is conceivable to classify the current state of the milling drum according to predefined criteria. A user or the further processing device can then determine if the milling drum complies with the set requirements for a scheduled milling assignment.

It is also conceivable that, at the request of an operator, the further processing device determines whether the milling drum in question is sufficiently suitable for an upcoming milling task.

If several data sets of different milling drums are stored in the memory device, the further processing device can inform the user on request which of the milling drum(s) is/are suitable for the scheduled milling assignment.

In the further processing device, for instance, the usability, the quality of the work result that can be produced with the milling drum and/or the efficiency of the milling drum can be determined. These parameters can be derived in particular from the stored data set containing the current state of the milling drum.

If the quality of the milling drum is assessed, the further processing device can for instance be used to determine which milling texture quality can be produced using the present milling drum. For instance, the milling drum in question or the milling drums in a pool can be assigned to a quality scale on the basis of the data set, or a determination can be made whether the required milling texture quality can be produced using that milling drum.

If the efficiency of the milling drum is determined, the further processing device determines which machine parameters are required to operate the milling drum as intended based on the present current state of the milling drum. For instance, it is possible to determine which drive power and/or which drive torque has to be applied for the intended use to achieve the desired work result. In correlation, the consumption of consumables (for instance, fuel consumption and/or coolant consumption) for the intended use can be determined.

When determining the usability (functionality) of the milling drum, a data set can be used to determine whether the milling drum is still basically usable for the intended or scheduled use.

The operation of a ground working machine is subject to requirements, for instance, to comply with economic or time specifications. One or more job data can be specified to comply with such specifications as well. Job data, as already mentioned above, are in particular data that have been or will be recorded during the operation of the milling drum, for instance the milling area, the milling volume and/or the milling mass of the material removed and/or the milling duration. In the context of the invention, job data may also include, for instance, a scheduled change to the material to be worked on, for instance, a milling path, a milling power, a milling work and/or a milling work time.

For instance, a mass or a milling volume of the material to be removed can be specified as the milling work. This may result in a required milling path and milling depth. A work per time can be specified as the milling power, for instance a mass to be machined per unit of time, a volume of material to be worked on per time or a surface or distance to be machined per unit of time. Working time may include the point in time when a given job has to be completed. It can further indicate an opportune moment to change the ground working tools, such as at the end of a shift or a scheduled downtime of the ground milling machine.

A characteristic feature in terms of the invention can in particular be an individualizing marking applied to the milling drum at a suitable location, for instance a bar code, a sequence of numbers or letters. A characteristic feature may also be an identifier present in or on an optically or electrically readable element, such as an active or passive transponder, for instance an RFID transponder or the like.

In the simplest case, the machine operator manually detects the characteristic feature of the milling drum.

Alternatively, provision may preferably be made for a reader to read the characteristic feature of the milling drum. The reader may be part of the ground milling machine or may be connected to the ground milling machine via a wired or wireless line to transmit data.

It is conceivable for the reader to be part of a separate computing unit designed to make wireless contact with the control unit of the ground milling machine. The separate computing unit can then be used to uniquely and wirelessly identify a milling drum. The separate computing unit may comprise the storage unit, in which the characteristic feature of the milling drum is linked to the data set containing information on the milling drum. The data set can then be transmitted to the processing device.

Preferably, the storage unit can be arranged on the milling drum, on which the characteristic feature and the data set containing information on the current state of the milling drum are linked. For instance, the storage unit may be an electronically readable and writable medium. In this case, a characteristic feature and/or the data set can be retrieved using a suitable reader, for instance, when the milling drum is changed, and transmitted directly to the processing device.

Alternatively, the storage unit is designed separately from the milling drum. Accordingly, after the characteristic feature on the milling drum has been detected (which can be done manually, for instance), the data set assigned to this characteristic feature and containing information on the current state of the milling drum has to be transferred from the storage unit to the processing device. For this purpose, provision may be made, for instance, to design the storage unit as a database, in which characteristic features and data sets are linked. Once the characteristic feature of the milling drum has been detected, the assigned data set containing information on the current state of the milling drum can be determined and transmitted to the processing device.

Accordingly, the processing device stores a data set of the current state of the milling drum before the start of a milling task. If the milling task is then subsequently performed, the milling tools are subject to wear. The state of the milling drum changes accordingly, compared to the initial state. During or after completion of the milling task, the change in the state of the milling drum resulting from the milling task can then be assessed or determined. The processing device then generates a new data set from the originally stored data set of this milling drum and the change in state that occurred during the milling task, which then reflects the current state of the milling drum. This new data set therefore represents an updated data set that takes into account the last milling task performed. Thus, it represents the state of the milling drum after the milling task has been performed

Accordingly, each milling task, for instance, can be considered as a single wear event. The resulting change in the state of the milling drum is combined with the state of the milling drum in a computation before the milling task is performed to determine the current state of the milling drum.

However, it is also conceivable for the ground milling machine to continuously determine the change in the state of the milling drum during the completion of a milling task and that a data set containing information on the then current state of the milling drum is generated at the end of the milling task. This variant takes into account the fact that the tools, which wear increasingly during the working process, affect the machine parameters and tool wear.