Method for determining whether a machine tool has warmed up, machine tool and method for machining workpieces

Abstract

The invention relates to a method for determining whether a machine tool having a numerical controller for machining a workpiece has warmed up. Axis data are obtained that relate to a position of a tool of the machine tool. An indication value is computed therefrom. It is then determined whether the indication value reaches a predefined threshold value. Furthermore, it is determined whether the machine tool has warmed up, the indication value's reaching of the threshold value indicating that the machine tool has warmed up. A method and a machine tool for machining workpieces, a computer program product, a computer-readable medium and a method for machining workpieces are provided.

Description

[0001] Method for determining whether a machine tool is overheated, machine tool and method for machining workpieces

[0002] The invention relates to determining whether a machine tool with a numerical control system for machining a workpiece has warmed up. It is assumed that during warm-up, the movements required for machining the workpiece are performed in a sequence. This sequence is repeated in several runs until the machine tool has warmed up.

[0003] A method for detecting thermal stability in machine tools and automating warm-up to improve process stability and production quality is presented.

[0004] In machine tools designed for machining or manufacturing workpieces, thermal changes result in physical effects on the mechanics. Changes in the mechanics can make it impossible to guarantee the exact position of high-precision machining operations (e.g. drilling) and thus the quality of the produced components. It is therefore common practice to warm up such machines before productive use. The duration of this process is not yet precisely known and is adjusted according to the state of the art based on experience. Likewise, the necessity or duration of warming up after a downtime is not known. Warming up for too short a time leads to rejected parts, while warming up for too long takes time away from operational operation and thus leads to lower efficiency.

[0005] DE 10 2018 001 830 A discloses a device for planning a warm-up operation, which creates a warm-up operation plan for a machine tool for machining a workpiece as the machining target. Therein, an assignment of at least one warm-up operation program to information about a workpiece to be machined by the machine tool and a processing time is recorded in the warm-up operation program. A warm-up operation program is selected based on a machining plan, and the duration of the warm-up operation is calculated based on the processing time in conjunction with the selected warm-up operation program. The warm-up operation is planned by creating a warm-up operation plan for the machine tool based on a start time and an end time of a warm-up operation, based on the input machining plan and the calculated duration of the warm-up operation.This takes into account a previously recorded operating time of the machine tool.

[0006] DE 10 2013 101 346 A discloses a control device for warming up a machine tool. Before machining a workpiece, a warm-up control device for a machine tool is activated, which performs a warm-up during which a main shaft rotational drive means and axis drive means are activated. A previously obtained calculation formula is used that provides the thermal displacement amount depending on the speed of the main shaft and the load of the main shaft motor. The amount of displacement due to the heat generated after the warm-up has started and which changes over time is calculated at each predetermined time period. Depending on the thermal displacement amount, a decision is made as to whether the warm-up should be terminated. Depending on the thermal displacement amount, a decision is also made as to whether the warm-up should be restarted after the warm-up has ended.If a warm-up restart is specified, the warm-up process will begin again. To adapt the procedure to different environments, operating conditions must be adjusted differently.

[0007] A disadvantage of the state of the art is that a plan must be made in advance or a formula must be derived in advance, and the method therefore loses efficiency because it cannot take into account changes in conditions, e.g. room temperature or mechanical wear of the axes, or requires the user to manually adjust the time period or the permissible value.

[0008] The object of the present invention is therefore to overcome the disadvantages of the prior art or at least to present an alternative. A method for determining whether a machine tool with a numerical control for machining a workpiece has warmed up, a machine tool for machining a workpiece, a method for machining a workpiece, a computer program product, and a computer-readable medium are provided. This object is achieved by the devices and methods according to the independent claims. Advantageous further developments can be found in the dependent claims.

[0009] The advantage here is that the warm-up process can be carried out using software control based on model results without the need for additional sensors. The process is purely data-driven and requires no sensors or measuring devices. The process is therefore based exclusively on the position data of the axles. By detecting convergence of the calculated indication value, i.e., the stability indicator, the warm-up process is fully automated.

[0010] In particular, compared to the state of the art, the calculation formula depends solely on the actual axis positions, and no values ​​for the motor speed or load are required. Therefore, no formula needs to be generated in advance. Furthermore, the presented method does not calculate and evaluate the difference between a maximum and a minimum value of the displacement magnitude. Instead, a characteristic value for the difference between two encoder systems is determined, and the convergence of the characteristic value is observed. With convergence toward a limit or threshold value, it can be concluded that no further mechanical expansion is occurring.

[0011] A further advantage over the state of the art is that when adapting to other environments, no adjustments, for example by a user, are necessary. This is achieved because this method also takes into account possible influences due to changes in the hall temperature as well as influences due to mechanical wear, and therefore no manual adjustments (e.g. by a user) are required. In other words, the present method does not use a fixed formula based on user input parameters to obtain the thermal displacement value, as in the prior art. The presented method takes all external influences (such as room temperature, wear, etc.) into account without further adjustments (e.g. by a user).

[0012] The process can be integrated into both existing and new machine tools. The optimization achieved through this process can save costs, energy, and materials. The project leading to this application has received funding from the European Union under the Horizon 2020 research and innovation program under grant agreement no. 871536.

[0013] According to a first embodiment, a method according to the invention for determining whether a machine tool with a numerical control for machining a workpiece has warmed up comprises obtaining axis data relating to a position of a tool of the machine tool. The method further comprises calculating an indication value from the axis data. Subsequently, it is determined whether the indication value reaches a predetermined threshold value, and it is determined whether the machine tool has warmed up. Reaching the indication value of the threshold value indicates that the machine tool has warmed up.

[0014] According to another embodiment, a machine tool for machining a workpiece with a numerical control is provided. The machine tool comprises a computing device configured to receive axis data and calculate an indication value from the axis data. The computing device can then determine whether the indication value reaches a predetermined threshold and whether the machine tool has warmed up. It is determined that the machine tool has warmed up if it is determined that the indication value reaches the threshold.

[0015] The method according to the invention or the machine tool according to the invention can ensure efficient warm-up without requiring any additional measurements or data to be collected.

[0016] In the method, obtaining axle data may comprise capturing the axle data by at least two measuring devices and / or reading the axle data from a memory, a database or a data carrier.

[0017] The machine tool may further comprise at least two measuring devices configured to acquire axis data relating to a position of a tool of the machine tool and transmit it to the computing device. Alternatively or additionally, the machine tool may comprise a data storage device, such as a memory, a database, or a data carrier, in which axis data is stored and configured to transmit stored axis data to the computing device.

[0018] By using measured data and / or stored axle data, the calculation of the indication value and the determinations can be further improved.

[0019] The measuring devices can be measuring transducers, i.e. sensors or measuring transducers, such as rotary encoders, or direct measuring systems.

[0020] In particular, at least one measuring device may be attached to a motor that moves a tool of the machine tool, and at least one measuring device may be a direct measuring system.

[0021] The calculation of the indication value can be carried out using a regression model, or the computing device can be configured to calculate the indication value using a regression model.

[0022] It has been shown that a regression model is particularly well suited for this calculation. A simple linear regression model is based on an influencing variable x and a target variable y. Using two parameters, a straight line is drawn through a cloud of points representing the existing values ​​of the axis positions in such a way that the linear relationship between x and y is described as accurately as possible and an error constant E is minimized.

[0023] Specifically, the formula for the regression line is: y = kx + d + E

[0024] The value k describes the indication value that is used for further analysis.

[0025] The values ​​of the axis positions depend on the physical dimensions of the installed geometry axes. For a length of 300 mm, example values ​​range from -150 mm to +150 mm. The difference considered between the two measuring systems, for example, is in the range of 0 mm to 0.2 mm. The calculated indicator value is then derived from the slope of the calculated regression line and lies, for example, in the range of 0.5 to 1.75. This value increases with thermal expansion and can be defined upon convergence with the limit value. Figure 4, for example, shows a limit value of approximately 1.5.

[0026] Determining whether the indication value reaches a predetermined threshold can be done by detecting a convergence of the indication value toward the threshold as a limit value. The computing device can further be configured to determine whether the indication value reaches a predetermined threshold by detecting a convergence of the indication value toward the threshold as a limit value.

[0027] Convergence has been shown to be a reliable means of determining whether the threshold has been reached.

[0028] The method can be further improved by detecting and / or reading temperature values ​​from at least one temperature sensor in the machine tool, and by determining whether the machine tool has warmed up taking the detected and / or read temperature values ​​into account.

[0029] The machine tool may further comprise at least one temperature sensor, and the computing device may be configured to take temperature values ​​of the temperature sensors into account when determining whether the machine tool has warmed up.

[0030] The additional use of temperature sensors can further optimize warm-up.

[0031] The machine tool can be controlled using the information from determining whether the machine tool has warmed up. The control includes at least one of warm-up start, warm-up continuation, warm-up stop, machining start, machining stop, and modifying the numerical control information for machining. A combination thereof is also possible. In the further embodiment, the computing device can be further configured to control the machine tool based on the determination of whether the machine tool has warmed up, wherein the control includes at least one of warm-up start, warm-up continuation, warm-up stop, machining start, machining stop, and modifying the numerical control information for machining. A combination thereof is also possible.

[0032] By being able to control the machine tool based on whether it has warmed up, workpiece machining can be fully automated.

[0033] According to a further embodiment of the invention, a computer program product is provided, comprising instructions that, when executed by a computer, cause the computer to execute a method according to the invention. The computer program product can be stored on a computer-readable medium.

[0034] According to a further embodiment of the invention, a method for machining a workpiece by the machine tool according to the invention is provided.

[0035] The embodiments show possible variants, whereby the invention is not limited to the specifically illustrated variants, but rather combinations of the individual variants with each other are also possible.

[0036] For a better understanding of the invention, it is explained in more detail using the following figures.

[0037] They show in a highly simplified, schematic representation:

[0038] Fig. 1 shows a machine tool with a tool for machining a workpiece according to an embodiment;

[0039] Fig. 2 shows a schematic flow diagram according to an embodiment,

[0040] Fig. 3 shows an example of the relationship between axis data and the indication value; and Fig. 4 shows the detection curve for the convergence of the indication value. By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or identical component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or identical component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and in the event of a change in position, these positional information must be applied analogously to the new position.

[0041] The description of the features of the embodiments below applies equally to the method and the machine tool, even if only one of the two forms is referred to. The same applies to the computer program product and the computer-readable medium.

[0042] In summary, the process can be described as follows:

[0043] Obtaining axis data, for example by reading the relevant data for the thermal stability indicator from the numerical control (NC)

[0044] Optionally, the data can be further processed, i.e. sorted, filtered, etc., or subjected to other processing.

[0045] Calculating an indication value from the axis data, for example, by sequentially calculating the thermal stability indicator based on axis data using a regression model for all three geometric processing planes (X, Y, Z), for example, by tapping two encoder positions, for example, on the motor and on the outside of the axis. The distance between the positions is then determined, e.g., measured, because this changes due to heat.

[0046] Determine whether the indication value reaches a specified threshold, for example, by detecting the convergence of the indicator. Determine whether the machine tool has warmed up, for example, by deciding whether to perform the warm-up process or not. This result can then be fed back into the machine's active process.

[0047] Optionally, based on this result, the machine control system can then automatically start, continue or abort the “warm-up” process.

[0048] Fig. 1 shows a machine tool 100 with a tool 101. This tool can be a milling head, a drill, a brush, or another cutting tool that engages a workpiece 300 to remove material. The tool is controlled by a numerical control 102 and driven in rotation by a spindle. The machine tool can include a computing device 110. Alternatively, the computing device can also be a standalone device.

[0049] According to the flowchart shown in Fig. 2, axis data 501 is first obtained from the computing device 110 in step 210. The axis data 501 describes the respective position of the axes of the machine tool 100. The method can be performed continuously. Alternatively, the determination that the machine tool has warmed up can also be interpreted as a termination condition, so that the method then ends. Steps 210, 220, 230, and 240 are then performed in each run.

[0050] The axis data 501 can be supplied to the computing device 110 in various ways.

[0051] Computing device 110 consists of or includes at least one processor or CPU (central processing unit). Computing device 110 may also consist of multiple processors, one or more of which may also be supporting processors, such as GPUs (graphics processing units). Processors from other computers may also be used, meaning that processing is outsourced.

[0052] The computing device 110 may further comprise a data storage device 106 on which input, output, intermediate result, and / or program data may be stored. Control data of the numerical control may also be stored on the data storage device 106. The data storage device 106 may refer to a memory 103, a database 104, and / or a data storage medium 105, the latter being connected to the computing device 110 or the machine tool 100 via a corresponding interface, such as a drive, or a wired or wireless interface.

[0053] The data storage device 106 does not have to be part of the computing device 110, it can also be remote, ie connected via a wired or wireless interface, such as a network.

[0054] Obtaining 210 the axis data 501 can be achieved by capturing 211 the axis data 501 using measuring devices. Alternatively or additionally, the axis data 501 can also be obtained by reading 212 from a data storage device 106. As already described, the data storage device 106 can be configured as a memory 103, a database 104, and / or a data storage medium 105. A combination of these is also possible.

[0055] The use of stored axle data 501 has the particular advantage that a warm-up that has already been carried out can be evaluated, re-simulated and the results can also be used for future warm-up.

[0056] Fig. 3 shows the axis positions of tool 101. The values ​​along the axes are plotted in nanometers. The X-axis refers to the position of tool 101 along one axis relative to the machine tool, and the Y-axis refers to another axis.

[0057] Fig. 3a illustrates the movements of tool 101 during a first pass of the movements required for machining, while Fig. 3b illustrates the movements during a second pass. The two passes shown are not directly consecutive, but are intended merely to illustrate the progression of the change.

[0058] It can be seen that the movements are similar to each other, but have a different position.

[0059] For example, the first pass moves in a range between 0.10 and -0.15 mm, while the second pass moves in a range between 0.05 and -0.20 mm.

[0060] An indication value 502 is then calculated using the axis data 501 in step 220. The indication value 502 represents a thermal stability indicator that indicates the stability of the mechanics of the machine tool 100, ie, the mechanical variability with respect to thermal changes.

[0061] The indication value 502 can be determined, for example, using a linear regression. This is also shown as an example in Fig. 3. The line marked with the reference symbol of the indication value 502 is also to be understood as a schematic representation.

[0062] The gradient k can be calculated for the line thus determined. This gradient k then corresponds to the indication value 502.

[0063] In the following step 230, it is then determined based on a predetermined threshold value 503 whether the indication value 502 reaches this threshold value 503. This is illustrated in Fig. 4. The x-axis in Fig. 4 is plotted against time, with 2 hours between the markings on the x-axis, for example. The y-axis carries the values ​​0 to 2, in which the gradient k is plotted as the indication value 502.

[0064] The threshold value 503 is the lower limit of the grayed-out area, which in Fig. 4 begins, for example, at approximately 1.45. If the indication value 502 now reaches or exceeds the threshold value 503, this reaching or exceeding is determined in step 230.

[0065] The determination 230 of whether the indication value 502 reaches a predetermined threshold value 503 can be carried out, for example, by detecting a convergence of the indication value 502 against the threshold value 503 as a limit value.

[0066] Reaching the indication value 502 of the threshold value 503 indicates that the machine tool 100 has warmed up. Optionally, temperature values ​​can be obtained from at least one temperature sensor in the machine tool 100. This can, in principle, occur at any time during the method. Steps 250 and 260 are shown in Fig. 2 for this purpose; these steps could also occur before the determination step 230 or even before the calculation step 220. These steps can be used for detection 250 and / or reading 260. Both alternatives can also be used. Detection 250 relates to the measurement of temperatures during the run, while reading 260 relates to obtaining the temperature values ​​from, for example, a data storage device 106.

[0067] This can then also be determined in the following step 240. This allows the method to be terminated. If temperature values ​​were obtained in steps 250 and / or 260, these can be taken into account when determining in step 240 whether the machine tool 100 has warmed up.

[0068] For example, even if the indication value 502 has reached the threshold value 503, but the machine tool 100 has not yet reached a lower temperature limit, it can be determined that the machine tool 100 has not yet warmed up.

[0069] It should be noted that the threshold 503 usually consists of a single value. However, it is also possible that the threshold 503 is represented by a range, as shown in Fig. 4. In this case, the threshold 503 would be an operating range that should not be exceeded.

[0070] If method 200 has not yet ended, a step 270 of controlling machine tool 100 based on the result of determination step 240 can optionally be performed. Here, machine tool 100 is controlled such that one or more control signals are sent to machine tool 100 to perform one or more of the following operations: warm-up start, warm-up continuation, warm-up stop, machining start, machining stop, and modifying the numerical control information for machining. A combination of these operations can also be sent as a signal to machine tool 100. Modifying the numerical control information can occur, for example, when it is determined that indication value 502 converges to a value that is below threshold value 503.In contrast to a manual adjustment of the threshold value 503, in this case an adjustment of the numerical control could also be carried out so that the distances during machining are changed in such a way as to compensate, for example, for a lack of thermal expansion of the tool 101 or the machine tool 100.

[0071] In particular, the method 200 can be continued even after machining of workpieces 300 has begun, and by determining whether the indication value 502 has reached or exceeded the threshold value 503, it can be determined if other adverse thermally induced changes in the mechanics occur. This could, for example, be excessive heat, causing the indication value 502 to fall below the threshold value 503, or exceeding the range of the threshold value 503, i.e., beyond the operating range. In this case, a machining stop signal could be sent in step 270.

[0072] As already described above, the features previously described with regard to the method 200 are to be applied in the same way to the machine tool 100.

[0073] In particular, machine tool 100 may comprise at least two measuring devices, which are designed, for example, as measuring transducers, ie encoders or measuring sensors, such as rotary encoders, or direct measuring systems.

[0074] In this case, at least one measuring device is advantageously mounted on a motor that moves a tool 101 of the machine tool 100, and at least one measuring device is a direct measuring system. Neither is shown in Fig. 1.

[0075] The first measuring device can therefore be a rotary encoder directly on the motor. This is also called an indirect measuring system because the measured value is derived from the motor movement.

[0076] The second measuring device, on the other hand, can be a direct measuring system, in which the position of the axis is actually measured. This can be done, for example, using a laser or similar device. In this case, the real axis position is measured directly, i.e., from the outside and actually.

[0077] The difference between the two possible measuring devices is that with the first measuring device a distance is already taken into account when the motor is moving, but due to mechanical influences (e.g. play between gears, wear, etc.) this distance only actually affects the axis later.

[0078] However, the axis is already considered offset by the program when the motor is moving.

[0079] However, by measuring the actual value of the axis position externally with the second measuring device, the aforementioned influences can be determined and taken into account. The second measuring device can be stationary, i.e., attached to the tool 101 or the machine tool 100, but alternative possibilities also exist. For example, a laser head can move along the axis and measure a reference position, or vice versa, i.e., the laser head is stationary and a measuring scale or coding to be measured moves along the axis, i.e., is moved along with the axis movement.

[0080] The difference between the different measuring devices changes as the machine tool 100 warms up and can be observed.

[0081] In other words, the second measuring device measures the actual position of the axis. There are different types of this depending on the machine design. One example is a fixed-mounted measuring head that measures a reference point (e.g., a coded metal strip). Another example is a measuring head that moves along the axis and measures a reference point (on the permanently installed, coded metal strip).

[0082] The machine tool 100 itself may also comprise corresponding elements that enable it to carry out the method 200 as set forth above. Another embodiment is a computer program product that includes instructions that, when executed by a computer, cause the computer to carry out the method 200 set forth above.

[0083] Another embodiment is a computer-readable medium on which the computer program product is stored.

[0084] Another embodiment is a method 400 for machining a workpiece 300 by the previously described machine tool 100.

[0085] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in this technical field due to the teaching of technical action by means of the objective invention.

[0086] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0087] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10. For the sake of clarity, it should be pointed out that in order to improve understanding of the structure, some elements have been shown out of scale and / or enlarged and / or reduced.

[0088] Reference symbol list

[0089] machine tool

[0090] tool numerical control

[0091] memory

[0092] database

[0093] Data carrier

[0094] Data storage facility

[0095] Calculating device

[0096] Method for determining whether a machine tool has warmed up

[0097] Obtaining the axle data

[0098] Recording the axle data

[0099] Reading the axle data

[0100] Calculating the indication value

[0101] Determine whether the indication value reaches a threshold

[0102] Determine whether the machine tool has warmed up

[0103] Recording temperature values

[0104] Reading temperature values

[0105] Controlling the machine tool

[0106] Workpiece(s)

[0107] Axle data

[0108] Indication value

[0109] Threshold

Claims

Patent claims Computer-implemented method (200) for determining whether a machine tool (100) with a numerical control (102) for machining a workpiece (300) has warmed up, comprising: Obtaining (210) axis data (501) relating to a position of a tool (101) of the machine tool (100); Calculating (220) an indication value (502) from the axle data (501); Determining (230) whether the indication value (502) reaches a predetermined threshold value (503); and Determining (240) whether the machine tool (100) has warmed up, wherein reaching the indication value (502) of the threshold value (503) indicates that the machine tool (100) has warmed up. Method (200) according to one of the preceding claims, wherein obtaining (210) axis data (501) comprises capturing (211) the axis data (501) by at least two measuring devices, and / or reading (212) the axis data (501) from a data storage device (106), such as a memory (103), a database (104), or a data carrier (105). Method (200) according to one of the preceding claims, wherein calculating (220) the indication value (502) is performed using a regression model. Method (200) according to one of the preceding claims, wherein the determining (230) of whether the indication value (502) reaches a predetermined threshold value (503) is carried out by detecting a convergence of the indication value (502) towards the threshold value (503) as a limit value.Method (200) according to one of the preceding claims, further comprising detecting (250) and / or reading (260) temperature values ​​of at least one. A temperature sensor in the machine tool (100), and wherein the determination (240) of whether the machine tool (100) has warmed up takes the temperature values ​​into account. The method (200) according to any one of the preceding claims, further comprising controlling (270) the machine tool (100) based on the determination (240) of whether the machine tool (100) has warmed up, wherein the controlling (270) comprises at least one of warm-up start, warm-up continuation, warm-up stop, machining start, machining stop, and modifying the numerical control information for the machining, or a combination thereof.A machine tool (100) for machining a workpiece (300), comprising: a numerical control (102); and a computing device (110) configured to receive axis data (501); calculate an indication value (502) from the axis data (501); determine whether the indication value (502) reaches a predetermined threshold value (503); and determine whether the machine tool (100) has warmed up, wherein it is determined that the machine tool (100) has warmed up if it is determined that the indication value (502) reaches the threshold value (503).Machine tool (100) according to claim 7, further comprising at least two measuring devices configured to acquire axis data (501) relating to a position of a tool (101) of the machine tool (100) and to transmit said data to the computing device (110); and / or a data storage device (106), such as a memory (103), a database (104), or a data carrier (105), in which axis data (501) is stored, and configured to transmit stored axis data (501) to the computing device (110). The machine tool (100) according to one of claims 7 to 8, wherein the computing device (100) is configured to calculate the indication value (502) using a regression model. The machine tool (100) according to one of claims 7 to 9, wherein the computing device (110) is configured to determine whether the indication value (502) reaches a predetermined threshold value (503) by detecting a convergence of the indication value (502) toward the threshold value (503) as a limit value. The machine tool (100) according to one of claims 7 to 10, further comprising at least one temperature sensor, wherein the computing device (110) is configured to take temperature values ​​of the temperature sensors into account when determining whether the machine tool (100) has warmed up.The machine tool (100) according to any one of claims 1 to 11, wherein the computing device (110) is further configured to control the machine tool (100) based on the determination of whether the machine tool (100) has warmed up, wherein the controlling comprises at least one of warm-up start, warm-up continuation, warm-up stop, machining start, machining stop, and modifying the numerical control information for machining, or a combination thereof. The machine tool (100) according to any one of claims 8 to 12, wherein the measuring devices are transducers, i.e., encoders or measured value transmitters, such as rotary encoders, or direct measuring systems. The machine tool (100) according to any one of claims 8 to 13, wherein at least one measuring device is attached to a motor that moves a tool (101) of the machine tool (100), and at least one measuring device is a direct measuring system. A computer program product comprising instructions which, when executed, cause the machine tool (100) according to any one of claims 7 to 14 to perform the method steps according to any one of claims 1 to 6. A computer-readable medium on which the computer program product according to claim 15 is stored. A method (400) for machining a workpiece (300) by a machine tool (100) according to any one of claims 8 to 16.

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