Calibration procedure and machine tool

Abstract

A method for calibrating a numerically controlled machine tool, which has at least a machine part A (101), a machine part B (102) which is movable relative to the machine part A (101) by a first controllable machine axis and is designed to carry a workpiece as well as several other controllable machine axes for the relative positioning of the workpiece with respect to a machining device of the machine tool, the method comprising the steps of: a) Fixing one or more measuring objects on the machine part B (102), b) Determining spatial positions of the measuring object(s) in one or more machine tool positions specified by a numerical machine control unit, c) determining one or more reference parameters designed for processing by the machine control unit to describe the position and orientation of the machine axes and the machine parts of the machine tool on the basis of the determined spatial positions of the measurement object(s) attached to machine part B (102), characterized in that the method further comprises the steps: d) determining a spatial reference position of a further measuring object (200) fixedly attached to the machine part A (101) at a time T1, e) Determining a spatial actual position of the measuring object (200) fixedly attached to the machine part A (101) at a later time T2>T1, f) Adjusting one or more specific reference parameters based on the determined reference and actual position of the measuring object (200) fixedly attached to the machine part A (101).

Description

The present invention relates to a method for calibrating numerically controlled machine tools and to a calibrateable machine tool with numerical control.BACKGROUND OF THE INVENTIONNumerically controlled machine tools are increasingly being used in the field of production, since these enable largely automated processes with short processing times and thus contribute, among other things, to a significant increase in the production volume in comparison to conventional non-numerically controlled machine tools.Embodiments of such machine tools having a plurality of numerically controllable machine axes, which can be designed, for example, as round and / or linear axes, are advantageous for machining a workpiece within the scope of a production process in this respect, since highly precise machining, which usually comprises multiple steps, can be carried out by a single machine tool very largely autonomously.In order to meet the requirements for the machining operations carried out by the numerically controlled machine tool, a prior calibration of the machine tool is necessary, which aims at a kinematic description of the various machine axes and the individual machine parts, which kinematic description is as accurate as possible and is to be used by the machine control, the position and orientation of which can change on account of numerous influences, such as ambient temperature, material wear or weight load, etc.The most accurate possible kinematic description of the machine axes and of the machine parts by specifying position and alignment contributes significantly to the machining quality of the workpieces to be machined by the machine tool, since otherwise machining cannot be ensured while complying with the workpiece-specific requirements, for example shape and / or position tolerances.Depending on the complexity of the machine tool in question, such a calibration method is designed to be extremely complex and time-consuming, since in the methods known from the prior art, for example according to the publications DE 10 2015 219 141 A1 or DE 10 2016 226 073 A1, as a rule one or more measurement objects designed for calibration are fastened in the machine and their positions are subsequently determined in a plurality of machine positions using a measurement device provided for this purpose.The method shown in the publication DE 10 2015 219 141 A1 was a method for calibrating a numerically controlled machine tool having one or two round axes, in which a single measurement object is fastened on a machine part configured to support workpieces and the position of which is determined in a plurality of different angular positions of the individual round axes by a suitable measuring device. On the basis of the determined positions of the measurement object, the position and orientation of individual machine axes and / or individual machine parts can be described.A calibration method constructed in a similar manner is shown in the publication DE 10 2016 226 073 A1. The method disclosed here for calibrating machine tools differs from that from the publication DE 10 2015 219 141 A1, inter alia, with respect to the device used for calibration, which in this case comprises two measurement objects fastened to a machine part, which are connected to one another via a spacer element.After the machine tool has been calibrated, the measurement objects fastened for calibration are removed and a workpiece to be machined by the machine tool can be machined, which workpiece is fastened on a machine part designed for this purpose, e.g. a pallet or a work table. After the workpiece has been machined by the machine tool, the latter is replaced directly by a workpiece still to be machined within the scope of an industrial manufacturing process, in order to keep the downtime of the machine tool as low as possible.Such a repetitive exchange influences the machine kinematics and therefore usually requires a new calibration of the machine tool after a certain time. Machine kinematics may also require renewed calibration of the machine tool due to further effects, for example in the form of significant changes in the operating conditions, for example the ambient temperature.The methods that are usually used, as explained by way of example on the basis of the aforementioned methods shown in the publications DE 10 2015 219 141 A1 or DE 10 2016 226 073 A1, are disadvantageous in that they are associated with corresponding time and work effort and therefore lead to increased downtime of the machine tool.In addition, such a time-consuming calibration method can falsify the calibration itself determined from the determined positions of the measurement objects, since the individual position determinations of the measurement objects in different machine positions take place in each case at relatively large time intervals with respect to one another and therefore substantial changes in the machine kinematics occurring between the individual determination steps cannot be detected or can only be detected insufficiently. Furthermore, the changes in machine kinematics caused by a relatively long time interval between the last position determination within the scope of such a calibration method and the start of the workpiece machining (e.g. due to a time-consuming process with removal of the measurement objects and clamping of the workpiece to be machined) are also not detected or are detected only insufficiently.From these points of view, in the prior art document DE 10 2012 207 336 A1, a simplified calibration method is found for this purpose, which is based on a first initial calibration of a single round axis and partial adaptations of this calibration at predetermined time intervals.In this method, the machine tool is initially calibrated with the single round axis by determining the spatial positions of a measurement object fastened on a machine table which is rotatably mounted via the round axis and is designed to receive a workpiece.For later adaptation of this initial calibration, a first and a second measurement object are mounted fixedly with respect to the machine tool outside the rotatably mounted machine table.Directly following the initial calibration, the distance of the first measurement object from the round axis with respect to a first spatial direction and the distance of the second measurement object with respect to a second spatial direction perpendicular to the first spatial direction are determined.At predetermined time intervals, these distances to the measurement objects mounted outside the machine table can be ascertained anew, in order to thus adapt the initial calibration of the machine tool accordingly on the basis of the initial distances determined.Although this procedure is due to the reduced information content compared to the initial calibration, which results from the re-determination of the distances and therefore only allows partial adaptations of the initial calibration, such a method represents an advantageous, time-saving measure for preserving the usually required machining quality of the machine tool, which can be carried out, for example, between individual machining steps without great effort.With an insufficiently accurate calibration of the machine tool in question, the requirements set for the machining of individual workpieces, such as shape and bearing tolerances, for example, can generally no longer be ensured, for which reason the workpieces machined under these circumstances are to the greatest part classified as rejects.Further prior art is also known from DE 10 2009 037 593 A1.SUMMARY OF THE INVENTIONAn object of the invention is to usefully develop a time-efficient method for calibrating a numerically controlled machine tool, starting from the closest prior art in DE 10 2012 207 336 A1, for use in a multiaxial machine tool.To achieve this object, a calibration method according to claim 1 and a numerically controlled machine tool according to claim 11 designed to use the calibration method are proposed.The dependent claims relate to preferred embodiments of the device according to the invention, which can be provided in each case individually or in combination.According to a first aspect, a method for calibrating a numerically controlled machine tool is provided, wherein the machine tool has at least one machine part A, a machine part B which is displaceable relative to the machine part A by a first controllable machine axis and is designed to support a workpiece, and a plurality of further controllable machine axes for the relative positioning of the workpiece with respect to a machining device of the machine tool. The method comprises the steps: a) fastening one or more measurement objects on the machine part B, b) determining spatial positions of the measurement object / objects in one or more machine positions of the machine tool specified by a numerical machine control unit, c) determining one or more reference parameters designed for processing by the machine control unit for describing the position and orientation of the machine axes and of the machine parts of the machine tool on the basis of the determined spatial positions of the measurement object / objects fastened on machine part B, and is characterized in that it furthermore comprises the stepsd) Determination of a spatial reference position of a further measurement object fixedly attached to the machine part A at a time T 1,e) Determination of a spatial actual position of the measurement object fixedly attached to the machine part A at a later point in time T 2>T 1,f) Adaptation of one or more specific reference parameters on the basis of the determined reference and actual position of the measurement object fixedly attached to the machine part A.comprising.After comprehensive initial calibration according to steps a) to c), which provides a complete kinematic description of the machine tool on the basis of the reference parameters processable by the control unit, the method according to the invention is particularly advantageous since, with relatively little outlay, the reference parameters can be at least partially adapted to a machine tool kinematics which has been changed in comparison to the initial state, if required. For this purpose, it is necessary, directly following the initial calibration, to determine the reference position of the measurement object attached to machine part A according to method step d). The adjustment of the reference parameters takes place at a later point in time according to steps e) and f) on the basis of a determination of the actual position of the measurement object, which usually differs from the initial reference position due to a changing machine tool kinematics.Such an adaptation taking place at predetermined time intervals is especially necessary in the case of machine tools with multiple machine axes, since, inter alia, influences caused by the operation of the machine tool, which can range from structural deformations of individual machine parts, for example due to the weight load of the workpiece to be machined, to thermally induced expansions of individual machine parts and / or machine axes and can lead to changes in the position and orientation of individual machine axes and / or machine parts or even of a plurality of machine parts. Furthermore, during the use of such a machine tool in industrial manufacturing processes, workpiece dispositions occur at regular time intervals, during which the workpieces to be machined are exchanged, which usually also brings about a change in the machine tool kinematics.These changes in the machine tool kinematics occurring during operation can only be absorbed insufficiently by a calibration, which is carried out only initially, on the basis of the measurement objects fastened to machine part B. An adaptation of the initially determined reference parameters by renewed fastening and position determination of the measurement objects on machine part B is disadvantageous, inter alia, for economic reasons with regard to the stoppage times of the machine tool associated therewith and, moreover, as a rule cannot be carried out simultaneously when the workpiece to be machined is fastened in the machine tool.From this point of view, the adaptation of the reference parameters on the basis of a measurement object fixedly attached to machine part A is found to be particularly advantageous since steps e) and f) of the method according to the invention can be carried out independently of a workpiece carried for machining machine part B and, moreover, does not impair the machining itself and only involves a low expenditure on time in comparison with the initial calibration.This low time outlay furthermore requires that a time of a position determination of the actual position of the measurement object attached to machine part A, carried out within the scope of the calibration method according to the invention, with subsequent adaptation of the reference parameters, and a time of a machining of the supported workpiece which usually follows it are very close to one another in terms of time. This is advantageous in that no substantial changes in the machine kinematics occur between the two specified times, for example on account of environmental influences.Furthermore, the relatively rapid adaptation of the reference parameters takes place within the scope of the calibration method according to the invention virtually in a geometric steady state, since the position determination of the measurement object attached to machine part A takes place even in the shortest time and thus, inter alia, there is a virtually constant machine temperature or work spindle temperature or a virtually constant deformation of individual machine parts caused by weight loading of the workpiece.In contrast to the method according to document DE 10 2012 207 336 A1, in the method according to the invention, the spatial actual position of an individual measurement object attached to machine part A is advantageously determined, from which at least three independent location information can be obtained and a higher information content related to the number of measurement objects is thus obtained.Furthermore, in contrast to the method from document DE 10 2012 207 336 A1, the effect of a deformation of individual machine parts in arbitrary machine positions caused by the weight load of the workpiece can be advantageously taken into account by the method according to the invention. The position determination necessary for this must comprise a complete, spatial description of the measurement object, which would not be possible by a pure distance measurement along a spatial direction according to the publication DE 10 2012 207 336 A1.Furthermore, the method according to the invention is advantageous in that different methods, for example methods according to publication DE 10 2015 219 141 A1 or publication DE 10 2016 226 073 A1, can be used for the initial calibration with measurement objects fastened on machine part B, which methods have to be carried out only once at the beginning. The later adaptation with the aid of the measurement object attached to machine part A is largely independent thereof.In a particularly preferred variant of the method according to the invention, the machining device of the machine tool is designed as a work spindle designed to receive a tool.In a particularly preferred variant of the method according to the invention, the machine part A of the machine tool with the measurement object fixedly attached thereto is configured such that it can be moved by a second controllable machine axis.This increases the flexibility of the machine tool with regard to possible travel movements, so that more comprehensive, more complex machining operations can be carried out on the workpiece.Furthermore, by moving the machine part A, the object to be measured fastened to it can be moved into a position with respect to the machine tool which is particularly favorable for determining the actual position.In a particularly preferred variant of the method according to the invention, the first controllable machine axis of the machine tool is designed as a first round axis.This results in the advantage, among other things, that the position of the common center of gravity of machine part A and machine part B indicated relative to machine part A generally does not change, or only changes to a slight extent, by a change in the angular position of the first round axis.In contrast, a translatory movement of machine part B relative to machine part A would lead to the position of the common center of gravity changing.In the case of the embodiment with a first round axis, it is thus ensured that the position of the measurement object fixedly attached to machine part A in relation to said common center of gravity of machine part A and machine part B also does not change, or changes only slightly.If the spatial distance between the object to be measured and the common center of gravity changes and is not almost constant, effects occurring over this distance, for example a structural change in the form of a bending, cannot be described, or can only be described insufficiently, with the aid of the method according to the invention.Therefore, an adverse influence in this sense on the accuracy of the method according to the invention is advantageously ruled out or at least is only extremely minor.The accuracy of the method according to the invention can be optimized to the effect that the measurement object fastened to machine part A has the smallest possible spatial distance from the common center of gravity of machine parts A and B.In a particularly preferred variant of the method according to the invention, the second controllable machine axis of the machine tool is designed as a second round axis, which is inclined or perpendicular with respect to the first round axis, for rotating the machine part A.The method can thus be advantageously used for the calibration of machine tools, in which the workpiece to be machined itself can be positioned via two round axes. This can be, for example, a five-axis machining center, in which machine part A is designed as a machine table rotatable about the second round axis and machine part B is designed as a pallet rotatably supported via the first round axis for supporting workpieces and, for example, three further machine axes designed as linear axes are designed for moving the machining device, wherein the machining device can advantageously be designed as a tool-carrying work spindle.With such a construction or a construction similar thereto of the machine tool, a relatively high degree of structural deformation caused by weight forces, for example of machine part A, can result given a corresponding orientation to the earth's gravity field. The bearing points for bearing the machine part A about the second round axis are usually arranged on two opposite end sides of the machine part A, whereas the first round axis with the machine part B supported thereby is generally arranged centrally between the bearing points of the machine part A and thus has a distance from the bearing points themselves. Such a structure can thus lead to a relatively severe bending of machine part A, which must be taken into account with regard to maintaining the machining quality of the machine tool.Since a position determination of the measurement object attached to the machine table can also be carried out between individual machining steps when the workpiece is clamped in, such deformations of the machine part A, caused for example by dead weight or similar effects, can be detected in a machine position to be assumed for the respective next machining step in the sense of the method according to the invention and taken into account by an adaptation of the reference parameters.In a particularly preferred variant of the method according to the invention, the spatial reference and actual position of the measurement object fixedly attached to machine part A is determined via a measuring device configured for touching.In an advantageous manner, the aforementioned positions of the measurement object fastened to the machine part A can be determined as time-efficiently as possible, since the measuring device used for this purpose, known as measurement probes, can be recorded, for example, directly by a recording device of the machining device of the machine tool configured for this purpose, and the position(s) of the measurement object fastened to the machine part A can be determined in a relatively short time by touching.The use of a tactile measuring device configured for touching, which can touch measurement objects in all spatial directions, is particularly advantageous; for example, in the form of a switching probe system, which has an optical switch as a sensor, which can detect deflections of a stylus configured for touching without wear.In a particularly preferred variant of the method according to the invention, the measurement object used for the calibration, which is fixedly attached to machine part A, has a geometry suitable for probing in three spatial directions.In this sense, the measurement object can be embodied, for example, as an annular geometry or else as a cylindrical cavity. The latter is advantageous in that the object to be measured can be protected by a protective device or cover of a closure-like design against contamination, for example due to material chips produced during machining of the workpiece, and thus the accuracy of the position determination is not adversely affected in the course of the method according to the invention.In a particularly preferred variant of the method according to the invention, the determination and / or the adaptation of the reference parameters is preferably carried out on the basis of desired positions of the measurement objects fastened to machine part B and / or of the measurement object attached to machine part A, which are determined from the machine positions specified by the machine control unit and these desired positions are compared with the determined spatial positions.In a particularly preferred variant of the method according to the invention, the determination of the actual position of the measurement object fixedly attached to machine part part A and the adaptation of one or more reference parameters take place at predetermined time intervals.The advantage resulting from a repeated execution of steps e) and f) of the method according to the invention is that changes in the position and orientation of individual machine axes and / or individual machine parts, which become noticeable only after a relatively long period of time, can also be taken into account in the adaptation of the reference parameters. These include, for example, setting effects, material wear, changes in the ambient temperature or else operationally induced material expansions, which can manifest themselves, for example, in the form of changes in length of individual machine axes. By means of a temporally recurring adaptation of the reference parameters on the basis of the actual positions determined in a predetermined temporal sequence, the negative effects on the machining quality of the machine tool resulting therefrom can be reliably compensated.In a particularly preferred variant of the method according to the invention, the latter further comprises the following steps:g) Determining further spatial actual positions of the measurement object fixedly attached to machine part A in a plurality of machine positions of the machine tool in a short time sequence at time T 2.h) Adaptation of one or more specific reference parameters on the basis of the determined reference position and the actual positions of the measurement object which is fixedly attached to the machine part A and which are determined in a plurality of machine positions.This has the advantage that additional location information of the measurement object fastened to machine part A is determined in a plurality of different machine positions and thus a more comprehensive adaptation of one or more reference parameters is made possible.Particularly in the case of a calibration of a machine tool with a second round axis for rotating the machine part A, such an adaptation of the reference parameters is particularly advantageous, since changes in the spatial orientation of the second round axis can be detected as a result and taken into account in the adaptation of the reference parameters and thus in the description of the machine tool kinematics.According to a further aspect of the invention, a machine tool is provided which comprises a machine part A, a machine part B which is designed to support a workpiece and is designed to be displaceable relative to the machine part A via a first controllable machine axis, a plurality of further controllable machine axes for the relative positioning of the workpiece with respect to a machining device, a machine control unit which is designed to numerically control the machine tool and a measurement device which is configured to determine spatial positions of measurement objects. The machine tool furthermore has a measurement object fixedly attached to the machine part A, and the machine control unit is configured to determine one or more reference parameters, designed for processing by the machine control unit, for describing the position and orientation of the machine axes and of the machine parts of the machine tool on the basis of determined spatial positions of one or more measurement objects attached to machine part B, to receive a spatial position of the measurement object fixedly attached to the machine part A determined by the measurement device, and to adapt one or more data sets stored in the machine control unit with the reference parameters, for describing the position and orientation of the machine axes and of the machine parts of the machine tool.In a particularly preferred exemplary embodiment, the machining device of the machine tool according to the invention is designed as a work spindle designed to receive a tool.In a particularly preferred exemplary embodiment, the machine part A of the machine tool according to the invention can be moved by a second controllable machine axis.In a particularly preferred exemplary embodiment, the first controllable machine axis of the machine tool according to the invention is designed as a first round axis for rotating the machine part B.In a particularly preferred exemplary embodiment, the second controllable machine axis is designed as a second round axis, which is inclined or perpendicular with respect to the first round axis, for rotating the machine part A.Such a combination of two round axes results in a high degree of flexibility with regard to the positioning of the workpiece to be machined, so that more comprehensive and / or more complex machining steps can be carried out.In such a construction of a numerically controlled machine tool, the machine part A is usually a machine table which can be rotated about the second round axis and on which the machine part B designed as a pallet is rotatably mounted via the first round axis and is designed to support a workpiece.Within the scope of an industrial manufacturing process, not only the workpieces themselves can be arranged with respect to the machine tool, but also the pallet together with the workpiece itself.The object to be measured which is fixedly attached to machine part A or in this case the object to be measured which is fixedly attached to the machine table is advantageously not affected in such a type of disposition and can still be approached by the measuring device of the machine tool, in order to determine its position, even after replacement of machine part B which is in this case designed as a pallet.In a particularly preferred exemplary embodiment, the measuring device of the machine tool according to the invention is configured to determine the spatial positions of measurement objects by touching.The measuring devices usually used for this can advantageously be provided in a tool holder, which, in the case of a movable machining device, can be approached by the tool holder in order to record the measuring device configured for touching in a completely or at least partially automated manner.In a particularly preferred exemplary embodiment, the measurement object fixedly attached to machine part A of the machine tool according to the invention has a geometry suitable for sensing in three spatial directions.This can advantageously be designed as an annular geometry or cylindrical cavity.In a particularly preferred exemplary embodiment, the machine tool according to the invention has five machine axes, of which two are designed as round axes arranged at an angle to one another or vertically and three are designed as linear axes, wherein the first round axis is designed for rotating machine part B relative to machine part A and the second round axis is designed for rotating machine part A, the machining device is designed as a work spindle designed for carrying a tool and movable over the three linear axes, and the measurement object fixedly attached to machine part A is designed as a cylindrical cavity or annular geometry.Brief Description of the FiguresFIG. 1 schematically shows a flow chart according to an exemplary embodiment of the invention FIG. 2 shows an enlarged view of the machine parts A and B with the measurement object fastened to machine part A according to an exemplary embodiment of the inventionDETAILED DESCRIPTION OF THE FIGURES AND PREFERRED EMBODIMENTS OF THE PRESENT INVENTIONExemplary embodiments of the present invention are described below with the aid of the appended figures. Identical or similar elements in the figures can be denoted here by identical reference numerals, but sometimes also by different reference numerals.It is emphasized that the present invention is in no way limited to the exemplary embodiments described below and the exemplary features thereof, but rather furthermore comprises modifications of the exemplary embodiments, in particular those which are comprised by modifications of the features of the described examples or by combination of individual or more features of the described examples within the scope of protection of the independent claims.FIG. 1 schematically shows a flow diagram according to an exemplary embodiment of the method according to the invention for calibrating a machine tool.In a first step S 01 of the exemplary embodiment shown, measurement objects required for calibration are fastened to machine part B. In a subsequent step S 02, the spatial positions of the objects fastened to machine part B are determined in a plurality of machine positions and subsequently transmitted to the machine control unit of the machine tool in the course of a step S 03.The machine control unit determines the reference parameters usable for describing the machine kinematics by the machine control unit on the basis of the position information transmitted in step S 03 in a step S 04.Subsequently, in a step S 05, the spatial reference position of a measurement object fixedly attached to machine part A is determined and, in a step S 06, is likewise transmitted to the machine control unit in order to be stored there.In a step S 07, which generally takes place later in time, the spatial actual position of the measurement object fixedly attached to machine part A is determined and, in a step S 08, is likewise transmitted to the machine control unit.The machine control unit then adjusts one or more reference parameters in a step S 09 on the basis of the reference and actual position of the measurement object fixedly attached to machine part A transmitted in step S 06 and step S 08, in order to be able to accurately describe the machine kinematics.In a subsequent step S 10, after a predetermined time, the calibration method is carried out again, beginning with step S 07, which comprises the determination of the spatial actual position of the measurement object fastened to machine part A.In this way, according to the exemplary embodiment shown, an adaptation of the reference parameters repeating at time predetermined time intervals is realized by carrying out steps S 07, S 08 and S 09 again.FIG. 2 shows the machine parts A and B with the measurement object fastened to machine part A according to an exemplary embodiment of the invention.In the shown section of an exemplary embodiment of the machine tool according to the invention, machine part A is designed as a machine table 101 which can be pivoted by the first round axis and on which, in the shown machine position, the machine part B designed as a cylindrical pallet 102 is mounted via the first round axis on the upper side.The configuration of the surface geometry of the pallet 102 has in this case a plurality of groove-shaped recesses 102 a, which are oriented toward the center of the pallet 102 and are designed for the pallet-side fastening of workpieces and / or the measurement objects used in the sense of the calibration method.Below the pallet 102, the measurement object 200 is mounted on the machine table 101. In the exemplary embodiment shown, the measurement object 200 has a cylindrical cavity 200 bto be used for the position determination, which cavity is introduced into a carrier element 200 aof the measurement object.Reference numerals denote reference numerals101 Machine table 102 Pallet 102 a Nuten for fastening workpieces / measurement objects on pallet 200 Measurement object 200 a Mounted on machine part A Support element 200 b Zylindrische cavity

Claims

A method for calibrating a numerically controlled machine tool, which has at least one machine part A (101), a machine part B (102), which is displaceable relative to the machine part A (101) by a first controllable machine axis and is designed for carrying a workpiece, and a plurality of further controllable machine axes for the relative positioning of the workpiece with respect to a machining device of the machine tool, wherein the method comprises the steps: a) fastening one or more measurement objects on the machine part B (102), b) determining spatial positions of the measurement object / s in one or more machine positions of the machine tool predetermined by a numerical machine control unit, c) Determination of one or more reference parameters designed for processing by the machine control unit for describing the position and orientation of the machine axes and of the machine parts of the machine tool on the basis of the determined spatial positions of the measurement object / s fastened to machine part B (102), characterized in that the method further comprises the steps: d) determining a spatial reference position of a further measurement object (200) fastened to machine part A (101) at a time T1, e) determining a spatial actual position of the measurement object (200) fastened to machine part A (101) at a later time T2>T1, f) adapting one or more determined reference parameters on the basis of the determined reference and actual position of the measurement object (200) fastened to machine part A (101).A method according to claim 1, characterised in that the machining device of the machine tool is designed as a work spindle designed to receive a tool.A method according to claim 1 or 2, characterized in that the machine part A (101) with the measurement object (200) fixedly attached thereto is configured to be movable through a second controllable machine axis.A method according to claim 3, characterized in that the first controllable machine axis is designed as a first round axis for rotating the machine part B (102).A method according to claim 4, characterised in that the second controllable machine axis is designed as a second round axis, which is inclined or perpendicular with respect to the first round axis, for rotating the machine part A (101).A method according to claim 5, characterised in that the determination of the spatial reference and / or actual position of the measurement object (200) fixedly attached to machine part A (101) is effected using a measuring device configured for touching.A method according to claim 6, characterised in that the measurement object (200) fixedly attached to the machine part A (101) has a geometry suitable for probing in three spatial directions.A method according to one of claims 1 to 7, characterised in that for the determination and / or the adjustment of the reference parameters, nominal positions of the measurement objects attached to machine part B (102) and / or of the measurement object (200) attached to machine part A (101) are determined from the machine positions predetermined by the machine control unit and these are compared with the determined spatial positions.A method according to one of the preceding claims, characterised in that the determination of the actual position of the measurement object fixedly attached to machine part A (101) and the adaptation of one or more determined reference parameters take place at predetermined time intervals.A method according to any one of the preceding claims, characterized in that the method further comprises the steps: g) determining further spatial actual positions of the measurement object (200) fixedly attached to machine part A (101) in a plurality of machine positions of the machine tool in a short sequence at time T2. h) adapting one or more determined reference parameters on the basis of the determined reference position and the actual positions of the measurement object (200) fixedly attached to machine part A (101) determined in a plurality of machine positions.A machine tool having a machine part A (101), a machine part B (102) which is designed to support a workpiece and is designed to be displaceable relative to the machine part A (101) via a first controllable machine axis, a plurality of further controllable machine axes for the relative positioning of the workpiece with respect to a machining device, a machine control unit designed to numerically control the machine tool and a measuring device configured to determine spatial positions of measurement objects, characterized in that the machine tool further has a measurement object (200) which is fixedly attached to the machine part A (101), and the machine control unit is configured to determine one or more reference parameters designed to be processed by the machine control unit for describing the position and orientation of the machine axes and of the machine parts of the machine tool on the basis of determined spatial positions of one or more measurement objects attached to machine part B (102), receiving a spatial position of the measurement object (200) fixedly attached to the machine part A (101) determined by the measuring device, and adapting one or more data sets stored in the machine control unit with the reference parameters for describing the position and orientation of the machine axes and the machine parts of the machine tool.A machine tool according to claim 11, characterised in that the machining device is designed as a work spindle designed to receive a tool.A machine tool according to claim 11 or 12, characterized in that the machine part A (101) can be moved by a second controllable machine axis.A machine tool according to claim 13, characterized in that the first controllable machine axis is designed as a first round axis for rotating the machine part B (102).A machine tool according to claim 14, characterized in that the second controllable machine axis is designed as a second round axis, which is inclined or perpendicular with respect to the first round axis, for rotating the machine part A (101).A machine tool according to claim 15, characterized in that the measuring device is configured to determine the spatial positions of measurement objects by touching.A machine tool according to claim 16, characterised in that the measurement object (200) fixedly attached to machine part A (101) has a geometry suitable for probing in three spatial directions.A machine tool according to one of claims 13 to 17, characterised in that the machine tool has five machine axes, of which two are designed as round axes arranged at an angle or perpendicular to one another and three are designed as linear axes, wherein the first round axis is designed for rotating machine part B (102) relative to machine part A (101) and the second round axis is designed for rotating machine part A (101), the machining device is designed as a work spindle designed for carrying a tool and movable via the three linear axes, and the measurement object (200) fixedly mounted on the machine part A (101) is designed as a cylindrical cavity (200b) or annular geometry.

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