EP3033596A1

EP3033596A1 - Reducing errors of a rotary device, in particular for the determination of coordinates of a workpiece or the machining of a workpiece

Info

Publication number: EP3033596A1
Application number: EP14750742.0A
Authority: EP
Inventors: Rainer Sagemüller; Dominik Seitz
Original assignee: Carl Zeiss Industrielle Messtechnik GmbH
Current assignee: Carl Zeiss Industrielle Messtechnik GmbH
Priority date: 2013-08-14
Filing date: 2014-08-14
Publication date: 2016-06-22
Also published as: US20160195869A1; CN105556253A; DE102013216093A1; WO2015022398A1; DE102013216093B4; US10073435B2; CN105556253B

Abstract

The invention relates to a method for reducing errors of a rotary device (11, 12), which comprises a first part (12), a second part (11), which can be rotated in relation to the first part (12) about an axis of rotation (A1) of the rotary device (11, 12), and a rotational-position measuring device (74, 75) for measuring the rotational positions of the first part (12) and of the second part (11) in relation to each other, wherein the rotational-position measuring device (74, 75) comprises a rotational-position sensor (74) and a measurement body (75) that interacts with the rotational-position sensor (74) for the measurement of the rotational position, wherein the rotational-position sensor (74) is connected to the first part (12) and the measurement body (75) is connected to the second part (11) or vice versa, and wherein the method comprises the following steps: - (21): errors of the rotary device (11, 12) caused by deviations between actual positions and actual orientations of the axis of rotation (A1) on the one hand and corresponding ideal positions and an ideal orientation of an ideal axis of rotation (A2) of the rotary device (11, 12) on the other hand are measured in a range of rotational angles, i.e., at various rotary positions of the first part (12) and of the second part (11) in relation to each other, and corresponding error measured values are obtained, - (23): expected fluctuations of the radial position of the first part (12) or of the second part (11) of the rotary device and/or fluctuations of the position of the first part (12) or of the second part (11) with respect to a direction tangential to the direction of rotation of the rotary device, which arise because of a deviation of the rotational motion of the rotary device (11, 12) from an ideal rotational motion about the ideal axis of rotation (A2), are determined from the error measured values for a plurality of rotational-position measurement locations of the rotational-position sensor (74), at which rotational-position measurement locations the rotational-position sensor (74) can measure the rotational position of the rotary device, - (25): in consideration of the expected fluctuations, at least one rotational-position measurement location of the rotational-position sensor (74) is determined, for which rotational-position measurement location the expected fluctuations of the position with respect to the direction tangential to the direction of rotation are smaller than for other possible rotational-position measurement locations and/or satisfy a specified condition.

Description

Reduction of errors of a rotating device, in particular for the determination of coordinates of a workpiece or the machining of a workpiece

The invention relates to a method for reducing errors of a rotary device which has a first part and a second part rotatable relative to the first part about an axis of rotation of the rotary device and a rotational position measuring device for measuring rotational positions of the first part and the second part relative to each other wherein the rotational position measuring device comprises a rotational position sensor and a measuring body cooperating with the rotational position sensor for measuring the rotational position, and wherein the rotational position sensor is connected to the first part and the measuring body is connected to the second part or vice versa. The invention further relates to an arrangement with which the method is executable. It gets away from it

assumed that the errors of the rotary device at least in part

are reproducible.

The invention also relates to a method for reducing errors of one

Turning device in the determination of coordinates of a workpiece or in the machining of a workpiece. The rotating device allows rotational movement of the workpiece about an axis of rotation of the rotary device during the determination of the coordinates or during the machining of the workpiece. The invention further relates to an arrangement with which the method is executable. It is assumed that the errors of the rotating device are at least partially reproducible.

It is known to rotatably support workpieces for the purpose of measuring their coordinates or for the purpose of machining the workpiece. For example, In the field of coordinate metrology, workpieces are arranged on rotatable tables (so-called turntables). In this way, the workpiece can be placed in various working orientations in which the coordinate measuring machine operates, i. Coordinates the workpiece. In particular, the coordinates of the workpiece may be measured continuously (eg, scanning) while the rotating device rotates the workpiece about its axis of rotation

The same applies to the machining of a workpiece by a machine tool. The workpiece can be brought into different working orientations to the Tool to edit. In particular, the workpiece can be continuously rotated while it is being processed.

In particular, the work orientation may be defined by a direction that extends perpendicular to the axis of rotation and through a point on the surface of the workpiece where the workpiece is scanned or on which the workpiece is machined. The force acting on the workpiece during tactile engagement of the workpiece with a button or when machining the workpiece can therefore act in particular perpendicular to the axis of rotation in the direction of the working alignment.

In the field of coordinate metrology, it is often advantageous to form-test a workpiece to scan the workpiece with a stylus having a nearly constant working orientation and working position relative to the rotating device while the rotating device rotates the workpiece. The working position and

Working orientation are not completely constant, since the workpiece is not usually arranged exactly rotationally symmetrical to the axis of rotation of the rotating device and / or is not formed or not exactly rotationally symmetrical. For example, can be a button of a

Coordinate measuring device, the tactile touches the surface of the workpiece _»held by the coordinate measuring machine in a fixed position and a fixed orientation, wherein the probe is deflected depending on the shape of the workpiece to be measured different degrees relative to a support of the probe. Due to the almost constant work alignment and working position errors of the

Coordinate measurement due to position-dependent and orientation-dependent errors of the CMM are minimized. The errors of the rotating device determine the measurement result significantly in this case. The speed of the measurement of the workpiece can be increased in many cases in this way.

A special measuring task in the field of coordinate metrology consists in the ripple analysis in the form of test especially rotationally symmetric areas of workpieces. The deviations of the actual shape from the ideal rotationally symmetric often show a waveform. However, the movement error of a rotary device, by which the real rotary motion of the rotary device deviates from an ideal rotary motion, can lead to the results of the

Ripple analysis are particularly inaccurate, in particular, are less accurate than Results in the measurement of coordinates of individual surface points of the

Workpiece

The same applies to the machining of a workpiece by a

Machine tool. When the desired production of a rotationally symmetric region waves can arise with very large amplitudes in a worst case, due to the motion error of the rotating device with which the workpiece is rotated during machining. _"

To reduce the errors of the rotary device, the rotary device can be designed so that the error meets specifications. In particular, air bearings can be used to support the rotatable parts of the rotating device and direct drives are used in motor-driven rotating devices. The smaller the error of the rotating device should be, the higher the design effort.

Alternatively or additionally, errors of the rotating device with a

Coordinate measuring device are measured, wherein a calibration body or an array of calibration bodies is placed on the rotatable part of the rotating device (for example, placed on the turntable) and measured. Measuring the errors of

Turning device with respect to all six possible degrees of freedom of movement by means of a coordinate measuring machine, which can also measure workpieces, but is time consuming. If high accuracy is required, the calibration must be repeated, for example, if the rotary device is exposed to temperature fluctuations. The same applies to a rotating device which is designed to _» rotatably hold workpieces in the processing area of a machine tool. The effort for a calibration is in this case in comparison to the coordinate metrology usually even greater, since in the field of coordinate metrology usually the coordinate measuring machine can be used for the calibration _» which also later performs the measurement of workpieces.

Eric Marsh, in Precision Spindle Metrology, ISBN 978-1-932078-77-0, especially Chapter 2, describes concepts for describing motion errors of a precision spindle.

WO 2013/007285 A1 discloses an arrangement for measuring coordinates of a workpiece and / or for machining the workpiece, wherein the arrangement has a first Part and having a relative to the first part movable second part, wherein the relative mobility of the parts is given in addition to any mobility of an optionally additionally attached to the arrangement of the probe at a

mechanical scanning of the workpiece for the purpose of measuring the coordinates by a displacement of the probe from a neutral position, wherein on the first or second part of a measuring body is arranged and on the other part, i. is arranged on the second or first part, at least one sensor, wherein the sensor is configured to generate a measurement signal corresponding to a position of the measuring body and thus according to the relative position of the first and second part.

WO 2013/007286 A1 discloses a method for calibrating a measuring arrangement for determining rotational positions of a rotating device which has a first part and a second part rotatable about a rotation axis relative to the first part.

DE 199 07 32S A1 discloses an angle measuring system for the high-precision determination of the angular position of an object rotating about a rotation axis.

WO 2011/064317 A2 discloses a referencing system-free executable calibration method for an angle measuring device.

EP 1 498691 A1 discloses a method for correcting the measurement results of a coordinate measuring machine, in which a workpiece is scanned continuously, with the following method steps; Determination of the dynamic bending behavior of the probe as a one- or multi-dimensional parameter field, in particular as

Dynamics tensor, calculation of correction values from the parameter field below

Consideration of the acceleration of the probe, correction of the measurement results with the correction values, where the parameter field describes the deviations in acceleration of the probe normal to the workpiece surface.

DE 100 06 753 A1 discloses a rotary-pivoting device for probes of Koordinatenmeßgeräten, with at least two hinges for

angular alignment of the probes. In the field of coordinate metrology a high precision of rotary devices, for example in the so-called roundness test is required to be checked in the circular contours of workpieces (eg the peripheral surfaces of cylinders) for deviations from the ideal circular shape.

In another case, in connection with the use of

Pitch measurements (i.e., angular distances in the direction of rotation about a rotational symmetry axis) »e.g. the angular distances of the teeth or flanks on gears, this very precise measuring Drehpositions- measuring devices of the rotating device are required, otherwise due to the error of the rotational position measuring device, an equally large measurement error otherwise arises. But also in other cases in the field of coordinate metrology or the

Machine tools require very precise measuring rotary position measuring devices.

In such rotational position measuring devices, the so-called eccentric error occurs and provides a large error contribution. The total eccentric error consists essentially of the eccentric error of the pivot bearing for supporting the rotational movement of

Turning device and the assembly error of the rotational position measuring device together. It is known to largely eliminate the total eccentric error by adjustment. As a result, the residual error contribution of the total eccentric error to the total error of the rotary device can become very small. A further possibility for reducing the eccentric error is to arrange a rotational position sensor at positions which are opposite to one another with respect to the rotational axis and to compute their measurement results in such a way that either the eccentric error is eliminated or calculated and can subsequently be used for correction.

Frequently, a rotational position measuring device in the field of

Coordinate metrology on a measuring body, which has a variety of distributed around the axis of rotation markings. The measuring principle is based on the fact that the

Markings divide a circuit around the axis of rotation into equal angular sections. Deviations from this uniform arrangement of the marks are therefore referred to as pitch errors. A determination of the pitch error by separate measurement is possible with the appropriate effort. If a reference Angle position of the measuring body is fixed, the pitch error can be corrected by calculation.

In order to reduce the already mentioned eccentric error from the outset, complex pivot bearing for supporting the rotational movement of the rotating device can be used, which bring only a small eccentric error with it. The cost of such pivot bearing is high and usually requires an adjustment to further reduce the eccentric error.

If the expense for the rotary mounting of the rotating device is lower, not only a relatively large eccentric error must be accepted, but also additional movement errors occur, i. unwanted translational and rotational movement components during the rotational movement of the rotating device, Basically, all the motion components are undesirable around which a real rotational movement of an ideal rotational movement of the rotating device differs. At an ideal

Rotational movement, all areas of the rotating part of the rotating device rotate at a constant radial position of the area with respect to the axis of rotation when a rotational movement takes place. As a result, the rotation axis of the rotary device is stationary, i. performs no translational movements in the direction of the axis of rotation or transverse to the axis of rotation and does not tilt. A tilt of the axis of rotation is

synonymous with a change in the orientation of the axis of rotation.

Movement errors of the rotary device can be measured and corrected during a later operation of the rotary device by calculation. However, the cost of the computational correction is very high, especially since the motion errors often have very small amplitudes. In particular, a correction at the place where the

Rotation position measuring device of the rotating device measures the rotational position is very expensive, since the movement error only leads to a rotational position measurement error in the range of fractions of arc seconds. Known methods for determining rotational position errors also require measurements that can take several hours. In addition, the temperature may change during this long measurement period, which in turn leads to a change in the motion error.

Another way to see the effects of motion error on the

To reduce rotational position measurement, it consists of so-called own storage use. These make it possible for the components of the rotational position measuring device (eg rotational position sensor and measuring element with markings) arranged on the relatively rotatable parts of the rotating device to control the movement errors of the rotational position sensors

Turning device to perform together. Such self-storage are particularly expensive.

In particular, when workpieces are to be rotated by a rotating device, which have at least regions _"which in large distance from the axis of rotation of

Turning device are arranged, the Drehpositionsmessfehler affects particularly strongly on the error in the measurement of the coordinates of the workpiece by a

Coordinate measuring device or on the machining of the workpiece by a

Machine tool off. If the control of the coordinate measuring machine or of the machine tool starts from the incorrect rotational position, this has an effect in proportion to the radial distance on the coordinate measuring error or the machining. For example, In practice, rotational position measurement errors occur up to one arcsecond, which at a radial distance of 0.2 m results in a positional error of the workpiece in a direction tangential to the circumferential direction of about one micrometer.

It is an object of the present invention to provide a method for reducing errors of a rotary device that reduces effects of movement errors of the rotary device on the measurement of the rotational position. Furthermore, it is an object of the present invention to provide an arrangement for carrying out the method.

The invention is based on the idea that movement errors of

Turning device, i. Deviations from an ideal rotational movement, depending on the Drehpositionsmessort the rotational position sensor of the rotating device have different effects on the measurement accuracy of the rotational position measurement. If the real one

Rotary movement of the rotating device compared to the ideal rotational movement leads to an additional movement in a direction tangential to the direction of rotation (ie tangential to the direction of rotation about the axis of rotation) of the rotating device, this falsifies the measurement of the rotational position. The relevant for the rotational position measuring device component of the movement error therefore runs in the direction tangential to the direction of rotation and is hereinafter referred to as a tangential motion error and is based on the respectively considered location. However, the invention is also based on the knowledge that that different motion processes, leading to the motion errors

(In particular also to the tangential motion error) of the rotating device, superimpose each other and thereby compensate or amplify, depending on which location of the rotating device is considered. The compensation or gain has an effect on the course of a rotary movement of the rotating device (in particular over the course of a complete revolution) differently, in terms of time and location. When considering a concrete location, namely, a rotational position measuring location at which the rotational position measuring device measures the rotational position of the rotary device, it changes

Compensation or gain during the course of the rotary motion. As a result, the tangential motion error is therefore locally dependent on the Drehpositionsmessort and time dependent on the course of the at the Drehpositionsmessort

impacting rotary motion.

In particular, the amplitudes of the tangential motion error differ over the course of the rotational movement at various possible rotational position measuring locations. The term amplitude denotes, as usual, the maximum deviation from the ideal rotational movement. However, not only can this amplitude be considered and a rotational position measurement location can be determined at which this amplitude is small or even minimal. Rather, the course of the tangential motion error during the

Rotational motion can also be viewed in another way and a Drehpositionsmessort be determined with a particularly favorable course, where "favorable" can be defined by at least one predetermined criterion z., There are measuring tasks in the

Coordinate metrology or processing tasks in the processing of

Workpieces by machine tools, which is to pay attention to precision with respect to a certain order of deviations between an ideal circular course of the outer circumference or inner circumference of the workpiece. For example, a trace having three maxima and three minima of deviation over one complete revolution about the axis of rotation or over a predetermined range of rotational positions (i.e., in particular part of a revolution) has the third order. The three maxima and three minima correspond to three waves. In the description of the tangential motion error as a spatial function (deviation from the ideal rotational motion as a function of

Rotational position) can of course be upper layers of several orders. The location function is equivalent to the time function (deviation as a function of the time of rotational movement) when the speed is known as a function of time or location, e.g. B. at constant speed The invention is not on the consideration of order three is limited. Rather, any orders of the tangential motion error can be considered.

The given criterion may also be referred to as a predetermined condition to be met. For example, a plot of the tangential motion error may be beneficial over the range of rotational positions (particularly over a predetermined range of rotational positions) traversed by the rotational motion with 9 waves (i.e., 9 maxima and minima of deviation) or some other predetermined number of waves. This is based on the idea that depends on the considered

Angular position of the rotational position measurement may occur a different number of waves and / or the amplitude of the motion error in the order (for example, 9 waves) may be different in size. In particular, to fulfill the predetermined criterion, therefore, for example, the rotational position measuring location is determined at which the amplitude of the movement error with respect to a predetermined order is maximum.

In this case, in order to return to the third order example, it is desirable that the measurement error of the rotational position sensor due to a movement error of the third order rotational error be particularly small so that the shape of the rotational position sensor

Workpiece can be measured as precisely as possible. Also in this case, order three is just one embodiment. For orders greater than one, the procedure may be similar, e.g. by determining a rotational position measuring location for which the tangential motion error of the rotary device with respect to the order is small, is minimal or satisfies a predetermined condition and hence a criterion (e.g., less than a predetermined limit).

Accordingly, at least one range of orders (for example, three to five waves) containing more than one order may be used. Instead of the number of waves of a deviation over a revolution around the axis of rotation of the

Rotary device or about the axis of rotational symmetry of the workpiece (or the number of waves of a deviation over a predetermined range of

Turning positions) can also be spoken by the frequency.

As a measure of the tangential motion error over a range of angular positions (in particular a range with all angular positions about the axis of rotation or a Subregion thereof) may in particular be the amplitude of the tangential motion error in the region (ie the amplitude of the position function or the time function, see above) or the amplitude after a transformation (in particular a Fourier transformation) of the tangential motion error into the frequency domain (ie the amplitude in

Frequency space} are used.

Based on the above-described findings of the invention, it is proposed, for the purpose of reducing errors of a rotary device having a rotational position measuring device, that movement errors of the rotary device, i. Error of the rotating device due to deviations between the real axis of rotation of the rotary device on the one hand and an ideal axis of rotation of the rotary device on the other hand, to measure and a favorable Drehpositionsmessort a

Determine rotational position sensor of the rotational position measuring device. In particular, a rotational position measuring location is determined at which the movement error has a smaller effect, in particular is smaller than for other possible rotational position measuring locations, and / or fulfills a predetermined condition. In particular, such as e.g. already mentioned above, are based on a given measurement task or processing task, for which the Drehpositionsmessort should be favorable.

For example, the movement errors can already occur during the production of the

Turning device (for example, turntable or swivel joint} are measured.

Specifically, there is proposed: a method for reducing errors of a rotary device comprising a first part and a second part rotatable relative to the first part about an axis of rotation of the rotary device and a rotational position measuring device for measuring rotational positions of the first part and the second part relative to each other, wherein the rotational position measuring device a

Drehpositionssensor and one for the measurement of the rotational position with the

Having rotational position sensor cooperating measuring body, wherein the

Rotary position sensor with the first part and the measuring body is connected to the second part or vice versa, and wherein the method comprises the following steps: - Error of the rotary device due to deviations between actual positions and actual orientations of the axis of rotation on the one hand and corresponding ideal positions and an ideal orientation of a ideal rotation axis of the rotary device on the other hand are in a range of Rotation angles, ie at different rotational positions of the first part and the second part relative to each other, measured and obtained corresponding error readings,

expected error of the radial position of the first part or of the second part of the rotating device and / or

Variations in the position of the first part or the second part with respect to a direction tangential to the direction of rotation of the rotating device, due to a deviation of the rotational movement of the rotating device of an ideal

Rotary motion around the ideal axis of rotation arise for a plurality of

Drehpositionsmessorten the rotational position sensor determines where the

Rotational position sensor can measure the rotational position of the rotary device,

- taking into account the expected fluctuations will at least one

Drehpositionsmessort the rotational position sensor determined for the expected fluctuations of the position with respect to the direction tangential to the direction of rotation o are smaller than for other possible Drehpositionsmessorte and / or

o fulfill a given condition.

It is also proposed: an arrangement for reducing errors of a

A rotary device comprising a first part and a second part rotatable relative to the first part about a rotation axis of the rotary device, and a rotational position measuring device for measuring rotational positions of the first part and the second part relative to each other, wherein the rotational position measuring device comprises

Having rotational position sensor cooperating measuring body, wherein the

Rotary position sensor with the first part and the measuring body is connected to the second part or vice versa, and wherein the arrangement comprises

a measuring arrangement that is designed to error the rotating device due to deviations between actual positions and actual orientations of the rotation axis on the one hand and corresponding ideal positions and an ideal orientation of an ideal rotation axis of the rotating device on the other hand in a range of rotation angles, i. at different rotational positions of the first part and the second part relative to each other, to measure and corresponding

Output error measurements to a forecasting device,

the prediction device, which is configured, estimates fluctuations of the radial position of the first part or of the second part of the error position from the error measured values Rotary device and / or variations in the position of the first part or the second part with respect to a direction tangential to the direction of rotation of the

Turning device, due to a deviation of the rotational movement of the

Rotary device of an ideal rotational movement about the ideal axis of rotation arise for a plurality of Drehpositionsmessorten the

To determine rotational position sensor, where the rotational position sensor the

Can measure the rotational position of the rotary device,

a determination device, which is designed taking into account the

expected fluctuations at least one rotational position of the

To determine rotational position sensor for which the expected variations in position with respect to the direction tangential to the direction of rotation

o are smaller than for other possible rotational position measuring points and / or

o fulfill a given condition.

In the further description, the determined rotational position measuring location is referred to as

"favorable" Drehpositionsmessort reference. In particular, the

Rotary position sensor arranged and / or aligned such that the determined

Drehpositionsmessort is set.

Also included in the scope of the invention is a method including the steps of the method for reducing errors of a rotary device, wherein, in addition, using the rotary device as part of a coordinate measuring machine, a workpiece is measured or using the rotary device as part of a

Machine tool, a workpiece is processed or using the

Turning a workpiece is rotated, before, during and / or after the measurement of the workpiece with a coordinate measuring machine or the machining of the workpiece with a machine tool.

In particular, the prediction device is designed, taking into account the expected fluctuations, to determine an angular position of the rotational position measuring location with respect to the axis of rotation and / or to determine an axial position of the rotational position measuring location with respect to the axis of rotation, taking into account the expected fluctuations.

The turning device is in particular part of a coordinate measuring machine for measuring a workpiece, part of a machine tool for machining a workpiece or designed _» to rotate a workpiece before, during and / or after the measurement of the workpiece by means of the coordinate measuring machine or the machining of the workpiece by means of the machine tool.

Rotary devices usually have an integrated sensor capable of measuring the rotational position. A known measuring principle is e.g. in EP 1 923 670 A1. Thus, it is a general principle of sampling a periodic pitch that a scanning head with a sensor unit scans one or more pitch periods of a gauge body on the other part of the rotating device. Also the

Rotary devices according to the present invention may comprise at least one sensor which detects a rotational position of the first part of the rotary device relative to the second part of the rotary device, wherein the sensor detects, in particular, markings on a measuring body which, during a rotational movement of the rotary device through the detectable region of the Move sensor through. The markings may be e.g. be line-shaped markings that extend in relation to the axis of rotation in the radial direction or extending parallel to the axis of rotation. Corresponding measuring bodies are also referred to as pitch discs. Such markings are usually detected by optical sensors. Ideally, a plurality of the markers are distributed around the axis of rotation at equal angular intervals to one another. Alternatively, other markings on the measuring body can be used to detect the rotational movement. Possible are e.g. magnetic markings, such as by an arrangement with distributed around the axis of rotation around magnetic

Elements. The corresponding sensor for detecting the magnetic marks may be e.g. be a magnetoresistive sensor. However, e.g. Hall sensors or other sensors are used, which are able to detect the strength or direction of a magnetic field. However, the invention is not limited to rotary devices which have an angle measuring device which detects markings on a measuring body. Rather, the measuring body may alternatively be e.g. have at least one magnet, so that a corresponding magnetic field is rotated during the rotational movement of the rotary device about the axis of rotation or, conversely, a rotatable part of the rotary device is rotated relative to the stationary magnetic field. At least one sensor detects the magnetic field and it is determined from the rotational position.

In the aforementioned actual positions of the (real) axis of rotation of

Turning device and the above ideal positions of the ideal axis of rotation Turning device are not rotational positions, which are measured by the rotational position measuring device. Rather, these are positions of a point on the respective axis of rotation in space. Embodiments for this

Position measurement will be described in more detail. For example, will

in measuring the deviations of the actual positions from an ideal position, a point of the real axis of rotation (for example, viewed at a certain axial position of the axis of rotation repeatedly during and / or after a rotational movement of the rotary device, that is it is (for example, indirectly the measurement of the positions of at least one point of one with the point on the axis of rotation

connected body) measured its positions and / or measured its deviations from the corresponding ideal position of the ideal axis of rotation. The measurement of the deviations of the actual orientations of the (real) axis of rotation can

In particular, be carried out in that the deviations of the actual positions of a plurality of points of the real axis of rotation are measured by a respective ideal position and from there the actual

Alignment is determined. However, this is only one possibility. It is also not absolutely necessary that deviations of the actual orientations of the real axis of rotation from the ideal orientation are explicitly determined. According to the invention, only an error of the rotary device due to deviations between actual positions and actual orientations of the rotation axis on the one hand and corresponding ideal positions and an ideal orientation of an ideal

Rotary axis of the rotating device on the other hand measured. For measuring the error, for example, as an alternative to considering two points of the real axis of rotation, only one point of the real axis of rotation can be considered, and also a point of a body at a distance from the real axis of rotation, the body being connected to the axis of rotation. As a measuring body for measuring the error, for example, a rotationally symmetrical body or an arrangement of rotationally symmetrical body (for example, a rod with two balls) can be used, the /

For example, the rotational symmetry axis is aligned to coincide with the real axis of rotation. Another example is a ball plate having a plurality of balls, which, for. B. at the same axial position along the axis of rotation spaced from each other. Yet another example is the pitch disk of a rotational position measuring system. In this case, at least two, preferably offset by 90 ° angular distance from each other

Rotary position sensors of the measuring system for measuring the measurement of the Rotational motion errors are used. In order to obtain further information about the rotational movement error at another position of the rotational axis, it is also possible to measure there, for example from a further rotational position measuring system or with a rotationally symmetrical body or a disc with a surface extending transversely to the axis of rotation as the measuring body. Alternatively to a

Rotary position measuring system with one pitch disc can also be another

Rotary position measuring system can be used. It must during the rotation (which can optionally be interrupted again and again) only at least two, preferably offset by 90 ° angular distance from each other locations the

Be measured rotational position. A body carrying part of a rotational position measuring system (for example, the body carrying the pitch disc) may also be used in other ways as a measuring body for measuring the rotational motion error. For example, the body may have a surface that is planar in a direction transverse to the axis of rotation, and the axial position of the surface may be measured at locations that rest during the rotational movement. Alternatively, the radial positions of an outer circumference of the body may be measured.

In particular, when the discussion is about a body or point connected to the axis of rotation, this means that the body or point belongs to the rotatable part of the rotating device, or upon rotation of the rotatable part of the rotary device

Turning device is rotated around the real axis of rotation and that the position and

Alignment of the body or the position of the point relative to the real axis of rotation or at least relative to a portion of the real axis of rotation in a rotation of the rotating device is not changed.

In particular, different movement errors of the rotating device, separated according to error sources and / or separated by degrees of freedom of movement of the real

Rotary axis relative to the ideal axis of rotation measured and / or determined.

Various sources of error are e.g. Tilts the real axis of rotation in

different directions and displacements of the real axis of rotation in different directions. Different degrees of freedom of movement of the real axis of rotation relative to the ideal axis of rotation are eg translational degrees of freedom transverse to the real or ideal axis of rotation and in the direction of the real or ideal axis of rotation. From the various errors, for example, immediate insights into favorable rotational position measuring points can be obtained. But it is also possible _» the expected total error of To evaluate turning device, eg at certain Drehpositionsmessorten or in areas of possible Drehpositionsmessorten,

In the range of angles of rotation of the rotating device in which the movement errors of the rotating device are measured _» can be in particular a whole

Turn, i. E. it will go through all sorts of rotational positions. For example, the measured values at standstill after each rotational movement of the

Turning device to be measured or during the rotation.

The measurements provide measured movement errors of the rotary device. From these measured errors now expected errors of the

Turning be determined, which are each expected for a Drehpositionsmessort. In particular, it is possible to interpolate and / or extrapolate between measured error values. In addition, it is possible to interpolate and / or extrapolate between already determined expected error values. As a result, e.g. For a range of possible Drehpositionsmessorte each the expected error of the rotational position measuring device and thus the rotating device. From the expected error, which may be equal to the measured error at the measuring points of the error measurement, at least one rotational position measuring location can now be determined and thus selected, at which a rotational position sensor of the rotary device measures the rotational position.

Once the movement errors have been measured, the expected variations can be determined as mentioned above with respect to the radial position of the first part or the second part of the rotary device and / or with respect to the position of the first part or the second part in the tangential direction. These radial and tangential

Fluctuations are equivalent to each other, if a corresponding equivalent

Drehpositionsmessort is considered. For example, a location of the first part of the turning device, which is at a certain angular position about the axis of rotation, and another location of the part of the turning device, which is at a 90 ° offset angular position about the

The axis of rotation is located, forming complementary locations. It is therefore possible to obtain the expected tangential motion error at a considered possible one

Determine rotational position measuring location from the expected or measured radial motion error at a 90 ° offset location. In particular, the motion error may be measured, for example, at a plurality of locations that are at different angular positions about the axis of rotation and whose angular positions are not the angular position of a possible

Rotary position measuring match. From this, too, the expected tangential motion error at the possible rotational position measuring location can be determined.

Therefore, the favorable rotational position measuring location can not be directly tangent to the determined expected fluctuations of the position with respect to a direction tangential to

Direction of rotation can be determined.

The Drehpositionsmessort the rotary position sensor is in particular a place where the other part of the rotary device is, ie the part _"where the

Rotary position sensor is not arranged, but the measuring body. To the

Rotational position measuring location, the rotational position is measured, i. the rotational position sensor observes a location at which different areas or points of the other part of the rotary device are located depending on the rotational position of the rotary device. This applies in particular to an optical detection. For example, in the case of the above

Measuring body with markings, the rotational position sensor detects the mark (s) at the Drehpositionsmessort. In the above-mentioned case of a measuring body, which has at least one magnet, so that the rotational position sensor determines the resulting magnetic field and therefrom the rotational position, it is in the

Drehpositionsmessort particular to a location that has the same angular position about the axis of rotation as the location of the rotational position sensor. In particular, the other part of the rotary device moves during the rotational movement through the

Drehpositionsmessort through when the rotating device performs its rotational movement. In this case, the term "move through" is to be understood as meaning that the part on which the rotational position sensor is arranged is regarded as a stationary part and therefore a rotational movement of the other part is perceived from the perspective of the rotational position sensor. As Drehpositionsmessort but can in all cases in which the for the

Drehpositionsmessung effective orientation of the rotational position sensor is independent of the Drehpositionsmessort fixed, that is, in the change of the

Drehpositionsmessortes only moves parallel, also the place to be considered, on which the rotational position sensor is arranged. In general, however, the

Rotary position sensor to a location other than a location of the same angular position be aligned and it can be effective for the measurement of the rotational position

Alignment of the rotational position sensor can be changed.

In particular, when the Drehpositionsmessort is a place through which moves the other part of the rotating device during the rotational movement, it may be a nearly point-like or linear location (eg, a line extending in the radial direction to the axis of rotation) or a flat Area, as it eg applies in the case of an optical sensor which simultaneously comprises a plurality of adjacent markers which follow one another in the direction of rotation about the axis of rotation on the measuring body. In this case, e.g. a point in the area of area (e.g., its center in the direction of rotation at one

predetermined position in the radial direction), whose coordinates can be specified as coordinates of the area and thus of the Drehpositionsmessortes. It is even conceivable that the Drehpositionsmessort is a volume range of the

Rotary position sensor is detected. Also in this case, a point of the volume area determined according to predetermined rules whose coordinates can be used as coordinates of the rotational position measuring location can be defined. In any case, the rotational position sensor measures the rotational position of the rotating device by interaction with the measuring body. If the location where the rotational position measuring location is located is the rotational position measuring location, a point of the

Rotational position sensor are defined whose coordinates as coordinates of the

Rotary position location that are specified.

If a Drehpositionsmessort known or fixed, then the direction results tangential to the direction of rotation according to the rules of geometry. The direction is the direction of the tangent to a circle concentric with the ideal axis of rotation passing through the rotational position location.

As will be explained in more detail below, the motion error is preferably measured with respect to all the degrees of freedom of the deviations between the real rotary motion and the ideal rotary motion, optionally except the translational degree of freedom in the axial direction. This does not allow for the expected variations (see above) only one angular position of

Determine Drehpositionsmessortes with respect to the axis of rotation, for example, determine the cheapest Drehpositionsmessort about a rotation around the axis of rotation. Rather, it can alternatively or additionally, taking into account the expected fluctuations, an axial position of the rotational position measuring location relative to the axis of rotation can be determined, for which the expected fluctuations fulfill at least one of the criteria mentioned in this description. Preferably, from the expected fluctuations, ie taking into account these fluctuations, both an angular position and an axial position of a favorable Drehpositionsmessortes determined. This is based on the knowledge _» that a particularly favorable Drehpositionsmessort is not available at any axial position with respect to the axis of rotation. The most favorable rotational position measurement location in a given axial section of the rotary device is typically a single location defined by its axial position and its angular position.

Hereinafter, another application of measuring the movement errors of a rotary device will be described. This application need not necessarily be a turning device having a rotational position sensor, although in practice this will usually be the case. However, the application described below can be combined with the previously described application of the measurement of motion errors. The motion error of the rotating device which can be optionally removed after the measurement of the rotation device first be measured, in particular with an independent measuring system _". Under a

stand-alone measurement system is in particular understood a measuring system _"which is not part of a coordinate measuring _machine" having the rotating device or into another case is missing from the rotating device to the rotating workpiece _"or not part of a machine tool having the rotating device or from the Turning device processed to be rotated workpiece. For example, to carry out the measurement of the movement errors with the standalone measuring system, a measuring body of the measuring system with the rotating device are coupled so that one or two rotationally symmetric measuring body of the measuring system with respect to the rotational axis of the rotating device is arranged approximately rotationally symmetric / are, so that at two spaced apart axial positions of Rotary axis can be measured. For example, distance sensors that are connected to the other part of the rotating device, ie the part of the rotating device on which the measuring bodies are not arranged, respectively at the two spaced apart axial positions measure the distance of the rotationally symmetric measuring body in two mutually transverse directions, which also run transversely to the axis of rotation. Preferably, for example, with still another distance sensor fluctuations in the axial position of at least one of Measuring body measured _» so that the five degrees of freedom of the movement error of the rotating device are detected by the independent measuring system.

In particular, as will be described in more detail below, after taking into account the results of the measurement of the movement error at least one working position and / or work orientation of a coordinate measuring device of a coordinate nmessgeräts or a machining tool a

Machine tool determined. The determination is made in particular with respect to a workpiece to be rotated with the rotating device. The rotation of the

Workpiece can be performed before, during and / or after the measurement of the workpiece by means of the coordinate measuring device or the machining of the workpiece by means of the machining tool. In addition, the results of the measurement of the movement error of the rotary device are used in the determination of a favorable rotational position measuring location for the rotational position measuring device of the rotary device, in particular as described above. This means that the measurement results of the motion error are used in two ways, namely for the adjustment of the Drehpositionsmessoiles and for the adjustment of the working position and / or working orientation of the coordinate measuring device or the

Processing tool.

It is another object of the present invention to provide a method of reducing errors of a rotary device in determining coordinates of a rotary device

Specify workpiece or when machining a workpiece that requires little metrological and design effort to the error of

Turning device with respect to a ripple analysis of rotationally symmetrical shapes or with respect to the generation of undulating deviations in the production of rotationally symmetrical shapes to keep low. In particular, the above-described methods of measuring a workpiece or the

Machining a workpiece with little effort be possible. Furthermore, it is an object of the present invention to provide an arrangement for carrying out the method.

The invention is based on the recognition that rotating devices, in particular for coordinate measuring device e and machine tools, in many cases different

Have sources of error that contribute to different error contributions to the total error of Guide the turning device. In particular, these various error contributions are translational errors, ie the axis of rotation moves in a straight line direction during the rotational movement, and rotational errors, ie the axis of rotation is dependent on the rotational position of the relatively rotatable parts of the rotating device

differently inclined to the ideal, non-variable axis of rotation and / or runs in different ways skewed to the ideal axis of rotation, the different error contributions compensate or reinforce, especially depending on

Working position and work orientation of the coordinate measuring device or the machining tool of the machine tool relative to the rotary device. But, as mentioned above, the rotational position sensor, which measures the instantaneous rotational position of the relatively rotatable parts of the rotating device, can perform this measurement more accurately or less accurately. The accuracy depends on whether the different error contributions on the Ott at which the rotational position sensor measures the rotational position compensate or amplify.

In addition, the invention is based on the recognition that individual sources of error in certain working positions and work orientations or at certain

Drehpositionsmessorten the rotational position sensor less than others

Working orientations and working positions or at other Drehpositionsmessorten affect the error of the measurement or on the machining of the workpiece. For example, For example, the actual rotational axis of the rotating device may tumble about a wobble axis that is perpendicular to the ideal axis of rotation. The wobbling motion is one

Rotary movement of the rotatable part of the rotating device about the wobble axis. In this case, the wobble angle (the angle between the real and the ideal axis of rotation) changes during a rotational movement of the rotating device. For example, in a measurement or machining of a workpiece in a working orientation that is parallel to said wobble axis and offset in the axial direction of the ideal axis of rotation (i.e., at an axial position other than the wobble axis), the effect

Tumbling only slightly off. The radial position of one of the

Turning device of rotated workpiece in the working orientation does not change.

In contrast, however, changes the radial position of the workpiece due to the

Tumbling motion in an orientation of the coordinate measuring device or the machining tool in the direction which is at the same axial position as the working orientation perpendicular to the ideal axis of rotation and perpendicular to said working orientation. Depending on the axial distance from the wobble axis around which the Tumbling takes place (the axial distance is determined as mentioned in the direction of the ideal axis of rotation) affects this error of the tumbling motion stronger or weaker.

To the case described above the determination of a favorable

In order to return to the rotational position measurement location, the rotational position measurement locations which do not result in a rotational position measurement error due to the tumbling motion are viewed from the rotational axis in the direction perpendicular to the ideal rotational axis and perpendicular to said working orientation.

A contribution to the solution of the o.g. Task is therefore, at least one

Work position and / or a work orientation of the coordinate measuring device or the machining tool to determine the expected error of

Turning device is small and / or meets a predetermined condition. With respect to the Drehpositionsmessortes the rotational position sensor is a contribution to the solution of the task is to determine at least one Drehpositionsmessort for which the expected error of the rotating device is small and / or meets a predetermined condition. For example, the predetermined condition requires that the error of the rotary device not reach or exceed a certain error value, or require a certain order of ripple (see above). In particular, at least one working position and / or working orientation or a rotational position measuring location can be determined for which the error of the rotating device is smaller than for other working positions and / or

Working orientations or Drehpositionsmessorte.

In the determination of the at least one working position and / or working orientation, in particular a predetermined measuring task for determining coordinates of the workpiece or a predetermined machining task for processing the

Workpiece are taken into account. For example, For example, the task may determine the work orientation of the coordinate measuring device or the machining tool, or set a possible or allowed working alignment range. The same can apply to the working position. Regarding work orientation, there are two

Working orientations in particular considered to be identical if they run parallel to each other, that can be brought together by parallel displacement with each other. In particular, the working position can be defined as an axial working position, ie the working position is used as the coordinate value of a coordinate axis (eg z-axis called), which coincides with the ideal axis of rotation. In particular, in this case, the work alignment can always be defined as extending perpendicular to the ideal axis of rotation, for example, when forces when probing a workpiece or

Editing a workpiece perpendicular to the ideal axis of rotation to be exercised.

In determining the at least one Drehpositionsmessortes of

Drehpositionssensors can in particular a predetermined measurement task for

Determination of coordinates of a rotatable with the rotatable part of the rotating device workpiece or a predetermined processing on processing for processing a rotatable with the rotatable part of the rotating workpiece are taken into account, For example, according to the task a result can be achieved, with respect to a rotational symmetry about an axis of symmetry of the workpiece, which ideally coincides with the axis of rotation of the rotating device, as small as possible

Deviation amplitudes with respect to a predetermined order (z. B. Procedure three _"ie three peaks and three minima on a revolution around the axis of symmetry) or with respect to a predetermined range of systems having, the location of the rotational position sensor can be chosen so in that the rotational position measurement error with respect to this measurement task or machining task at the location is minimal or meets a predetermined condition.

In this description, when the rotational position measurement error of the

Drehpositionssensors the speech is _» refers to the measurement error only on the

Error component based on a movement of the real axis of rotation of the rotating device relative to the ideal axis of rotation of the rotating device. All the other error _components' particularly the error component of the rotational position measuring device, which because of an inherent error of the measuring device also occurs at an ideal rotational movement of the rotating device (for example, irregularities in the line dividing a line disk), the error component due to eccentric positioning of the axis of rotation (in particular due to an eccentric Drehlagerung for storage of

Rotational movement of the rotation axis) and the error component due to an eccentric positioning of a rotatable part of the rotational position measuring device _" are not considered

For example, a machining tool can only be operated in a certain working orientation on the machine tool. Accordingly, the mobility of a tactile or optical probes of a coordinate measuring machine, with which a workpiece is to be measured, for example, be limited for reasons of reducing the measurement error so that only a work orientation or a small range of different working orientations is possible. Depending on the workpiece to be measured or machined, it may alternatively or additionally only be possible to arrange the coordinate measuring device or the machining tool in a specific working position or in a specific range of working positions relative to the rotary device. For example, if it is a very long one

Workpiece whose end is to be measured and which is to be aligned in the axial direction of the rotation axis of the rotating device, the end of the workpiece, for. either very close to a holder of the rotating device or very far away from this holder can be arranged.

It should therefore be emphasized again that both the working position and the work orientation are related to the rotating device and not on the workpiece. Regarding the errors of the rotating device, it is usually exclusively or

predominantly on this working position and / or this work orientation with respect to the rotating device. In addition, there may be other influences on the error of the rotary device, e.g. the weight of the workpiece, the moment of inertia of the workpiece, the force that the coordinate measuring device or the

Machining tool applies to the workpiece, other parameters of the

Measurement / machining of the workpiece (eg cutting depth of the tool) and / or the rotational speed with which the rotating device rotates the workpiece. At a

Embodiment of the present invention, at least one of these additional factors and / or any combination of these factors in the award of the error of the rotating device at the respective work orientation and / or working position to go. For example, For example, a measurement of the error of the rotary device can be carried out while the respective influencing factor or the respective combination of influencing factors is effective.

In many cases, the translational error of rotary devices contributes less to the overall error of the rotary device than the rotational error due to a tilting (tumbling) of the actual axis of rotation relative to the ideal axis of rotation. In analogy to the leverage laws of mechanics, the greater the distance (in the axial direction of the axis of rotation) to the wobble axis, the greater the effect of the rotational error is. As mentioned above, the wobble angle during the rotational movement of the rotary device, error contributions due to a constant, varies with the

Rotational motion non-changing tilt angle _» can be easily determined and corrected, for example, by changing the orientation of the real, tilted axis of rotation so that it coincides with the ideal axis of rotation.

The determination of the favorable with respect to the error of the rotating device working positions and working arrangements not only has the advantage of reduced errors, but can, as will be described below, also determine with very little measurement effort. Since with reduced error coordinates of workpieces can be measured or workpieces can be edited, the design effort for the rotating devices can be reduced.

Preferably, the error of the rotary device is not for all possible

Working positions and / or working orientations of the coordinate measuring device or the machining tool measured and / or preferably, the error of the rotating device is not measured for all working position (s) and / or work orientation (s) that at a given measurement task or a predetermined

Processing issues occur / occur. Rather, it is preferred that the error of the rotary device be limited to only a few rotational positions of the rotary device and only a few, e.g. two axial (relative to the axis of rotation of the rotary device},

Measuring positions is measured. At least the error is measured for each axial position for at least two rotational positions of the rotating device. Alternatively, the error of the rotary device may be measured, for example, at at least one axial position of the rotation axis continuously or quasi continuously during a rotational movement of the rotary part of the rotary device. This is possible, for example, by using capacitive or optical measuring sensors which detect the position or the

Measure relative position of a rotating together with the rotatable part of the rotating test specimen (also called calibration). In any case, the error of the axis of rotation is preferably measured in such a way that all error sources or all significant error sources are taken into account. What is important is a source of error if it can provide or provide a substantial contribution to the total error of the turning device.

In particular, the motion error of the rotary device with respect to all degrees of freedom of the deviations between the real rotary motion and the ideal Rotational motion measured, optionally with the exception of the translational degree of freedom in the direction of the axis of rotation. In a section in the axial direction of the rotation axis, which has no pivot bearing, which store the rotational movement, are five (or optionally four)

To detect degrees of freedom of motion error, namely all three

translational degrees of freedom or optionally the two translational degrees of freedom transverse to the axis of rotation and the rotational degrees of freedom with respect to two axes of rotation which extend transversely to the axis of rotation. The rotational degree of freedom about the axis of rotation is desirable and therefore not attributable to the movement error. For example, For example, such an axial section of the rotating device can be measured as will be explained with reference to the attached figures.

A variant consists in the rotational degrees of freedom by measuring the

Deviations in the axial direction to be measured at different points of a measuring body (for example, a disc-shaped, in particular rotationally symmetric measuring body on the outer circumference and translational degrees of freedom in the radial direction can be measured). Kicking in the different places

different deviations in the axial direction, this is based on a rotational motion error about at least one axis of rotation, transverse to

Rotary axis runs. Unless otherwise explicitly stated, the axial direction in this description is always understood to mean a direction parallel to

Rotary axis runs or coincides with the direction of the axis of rotation. Of the

Disk-shaped measuring bodies may for example be an integrated part of a turntable, for example the disc-shaped part which forms the turntable surface for supporting the workpiece to be rotated. Alternatively, another rotatable part of the

Turntable, which in particular has a flat surface extending perpendicular to the axis of rotation (eg the so-called face plate of the turntable) can be used as a measuring body. A flat surface of this measuring body or another

Measuring body may have deviations from the ideal flat course. Before or after the measurement of the movement error of the rotary device, which is measured using the flat surface, known deviations from the ideal flat course can be corrected. In this way, the accuracy of the measurement of the motion error is improved.

However, if movement errors of the rotary device are to be considered and measured concerning an axial portion of the rotary device, which has at least one pivot bearing for supporting the rotational movement of the rotating device, it can lead to constraining forces due to the pivot bearing. Depending on these constraining forces, the rotating device may therefore no longer be regarded as rigid, as is generally the case in axial sections without pivotal mounting. The measurement of the degrees of freedom of the movement error on one axial side of a pivot bearing can therefore not be transferred or not in all cases to the motion error on the opposite axial side of the pivot bearing. Under certain circumstances, the movement error is therefore on both axial sides of the pivot bearing of the rotating device with respect to some or all degrees of freedom

Measure movement before it can be determined from the favorable Drehpositionsmessort and / or the working position and / or work orientation. Alternatively, the movement error can only be measured on one axial side of the rotary bearing and a rotational position measuring location can only be determined on this axial side.

Embodiments of the measuring arrangement will be discussed in more detail, for example. a calibration body for performing the measurement on the rotatable part of

Rotating device are arranged, wherein the calibration at at least two different axial positions with respect to the real axis of rotation

Has rotationally symmetric measuring body and wherein at different

Rotary positions of the rotatable part of the rotating device respectively at the axial

Positions of the measuring bodies whose radial position in two different, intersecting directions are measured. In this way, the radial positions which are dependent on the rotational position can be measured directly at the axial measuring positions, and the tilting of the real axis of rotation relative to the ideal rotational axis can also be determined therefrom, for example for the individual rotational positions. Instead of a single calibration body, an arrangement of several calibration bodies can also be used. Instead of the calibration body described above, for example, another calibration can be used, for example, a plurality of Kalibrierkugeln, which are arranged approximately at the same axial position of the axis of rotation adjacent to each other and connected to each other, for example in the form of a so-called ball plate, with already known per se Measuring methods, the positions of the ball centers of the balls in space (ie their three-dimensional coordinates) are measured, for different rotational positions of the rotating device. By the measurements, measured errors of the rotary device are obtained. From these measured errors now expected errors of the rotating device can be determined, which are each expected for a working position and work orientation of a coordinate measuring device or a machining tool of a machine tool. In particular, it is possible to interpolate and / or extrapolate between measured error values. In addition, it is possible to interpolate and / or extrapolate between already determined expected error values. As a result, one obtains eg for a range of possible working positions and / or for a range of possible working orientations of the coordinate measuring device or the

Machining tool each the expected error of the rotating device. From the expected error, which may be equal to the measured error at the measuring points of the error measurement, at least one working position and / or working orientation can now be determined, in particular as already generally stated above for the error of

Turning device described.

Specifically, there is proposed: A method for reducing errors of a rotary device in determining coordinates of a workpiece or machining a workpiece, wherein the rotary device rotates the workpiece about an axis of rotation of the rotary device during the determination of the coordinates or during machining of the workpiece and wherein the method comprises the following steps:

Errors of the rotary device due to deviations between actual positions and actual orientations of the rotation axis on the one hand and corresponding ideal positions and an ideal orientation of the rotation axis on the other hand (hereinafter: movement errors of the rotary device) are in a range of rotation angles, i. at different rotational positions of two rotatable relative to each other about the axis of rotation parts of the rotating device, measured and it will receive corresponding error measurements,

the error measurement values filter the expected expected error values

Rotary device determines which of a plurality of relative working positions and working orientations of a coordinate measuring device for determining the coordinates of the workpiece or a machining tool

Machine tool for machining the workpiece on the one hand and the

On the other hand, rotating means may be expected to be filtered over at least a predetermined range of the number of waves of the deviations between actual positions and actual orientations of the axis of rotation on the one hand and corresponding ideal positions and an ideal alignment of the

On the other hand, about a complete revolution or a part of one revolution of a rotational movement of the rotating device,

from the filtered expected error values of the rotary device, at least one working position and / or working orientation of the coordinate measuring device or the machining tool is determined, for which the filtered expected error value of the rotary device for a given measurement task for determining coordinates of the workpiece or a predetermined processing Task for machining the workpiece

o is smaller than for other job positions and / or work orientations and / or

o met a given condition.

It is also proposed; An arrangement for reducing errors of a rotary device in determining coordinates of a workpiece or machining a workpiece, the rotary device allowing rotational movement of the workpiece about a rotation axis of the rotary device during the determination of the coordinates or during machining of the workpiece, and wherein the Arrangement comprising:

a measuring arrangement which is configured, errors of the rotary device due to deviations between actual positions and actual orientations of the rotation axis on the one hand and corresponding ideal positions and an ideal orientation of the rotation axis on the other hand in a range of rotation angles, i. at different rotational positions of two relatively rotatable relative to each other about the axis of rotation parts of the rotating device to measure and corresponding

Output error measurements to a forecasting device,

the prediction device, which is designed to determine from the error measurement values filtered expected error values of the rotary device which are suitable for a plurality of relative working positions and working orientations of a coordinate measuring device for determining the coordinates of the workpiece or a machining tool of a machine tool for machining the workpiece on the one hand and On the other hand, the rotating device may be expected to be filtered over at least a predetermined range of the number of waves

Deviations between actual positions and actual orientations the axis of rotation, on the one hand, and corresponding ideal positions and an ideal orientation of the axis of rotation, on the other hand, over a full or part of one revolution of a rotary movement of the rotary device,

a determination device, which is configured, from the filtered expected error values of the rotary device at least one working position and / or

Working orientation of the coordinate measuring device or the

Determine a machining tool for which the filtered expected error value of the rotating device in a given measurement task for determining coordinates of the workpiece or a predetermined machining task for machining the workpiece

o is smaller than for other job positions and / or work orientations and / or

o met a given condition.

Each of the filtered expected error values of the rotary device is valid for one of the plurality of relative working positions and working orientations of the coordinate measuring device or the machining tool _" ie a working position _{" of} a work alignment or a combination of a work position with a

Assigned to work orientation.

In particular, the determined work position and / or work orientation of the

Coordinate measuring device or the machining tool set, that is, the coordinate measuring device or the machining tool has after setting this working position and / or work orientation.

The optimization of the working position and / or work orientation has the advantage that the accuracy of ripple analyzes can be significantly increased. If the maximum permissible error due to a ripple is very small, this error can already be achieved due to an unfavorable working position and / or work orientation. The invention makes it possible to avoid such an unfavorable arrangement.

In particular, the measuring device which measures the movement errors of the rotary device can be part of the coordinate measuring machine which has the coordinate measuring device whose favorable working position and / or working orientation is determined. For example, the coordinate measuring device at different rotational positions of the Turning device and various working positions and / or working orientations from a measuring body, which is arranged on the rotating device, and the

Coordinate measuring device determined in this way the movement errors. Furthermore, the coordinate measuring machine can have the prediction device and the determination device. This applies not only to the calculation of filtered expected error values, but also to a variant of the calculation of expected error values without filtering according to a predetermined range of the order of the ripple or completely without

Filtering gets by. Such expected error values may also be used to determine a favorable work position and / or work orientation. With the exception of the filtering step and the associated steps (such as transformation into the frequency domain and

Reverse transformation) are carried out in the same way.

This embodiment of the arrangement or this embodiment of the method solves the following problem; As mentioned above, it is possible to detect errors of a rotary device (e.g., a turntable on which a workpiece to be measured can be placed) and to computationally correct them during operation of a coordinate measuring machine and the rotary device. However there is

Coordinate measuring machines (and accordingly also machine tools), which have no functions for the computational correction of the errors of the rotating device. In another case, the cost of the high cost of computational correction should be avoided.

According to the invention, it is possible to design the control of the coordinate nmessgeräts so that they the functions of the measuring device for measuring the

Can control motion error of the rotary device. In particular, the control of the coordinate measuring machine may have corresponding software. Furthermore, the controller, for example, in turn, by appropriate software, to be able to control the functions of the forecasting device and the detection device and / or execute. The invention ^reduces' but not only in this case the cost of a reduction in the errors of a rotary device. Rather, it can

In particular, the effort for the measurement of the motion error can be reduced by measuring the movement error as mentioned elsewhere in this description and determines the favorable arrangement of the coordinate measuring device or the machining tool and / or the favorable Drehpositionsmessort becomes. In particular, it is also possible to carry out the invention in addition to a previous computational correction of the errors of the rotary device. As a result, a particularly high accuracy is achieved, since in particular residual errors of the computational correction, which are in the range of 5% of the total error, can be further reduced.

With the integration of the measuring device, the forecasting device and the

Determination device can therefore be overcome the disadvantage that a

Coordinate measuring device is not capable of receiving correction data to correct the error of the rotary device.

In general, not only when integrating the measuring device in a coordinate measuring machine, the invention has the advantage that a favorable working position and / or work orientation can not only be where the motion error of the rotating device was also measured. Rather, expected error values can also be calculated from the measured values of the movement error for other working positions and / or work orientations. As a result, it can be avoided that only values from the specification of the rotating device that are not related to a specific working position and / or work orientation can be specified as the expected error. Such error values from the specification are usually much larger than the actual error values at a favorable working position and / or working orientation. In particular, in ripple analyzes, the error value from the specification of the rotary device is usually much larger than the actual error of the rotary device in relation to the number of a given order. By filtering the measured

Movement error values can therefore often be a favorable working position and / or

Working orientation can be found in which the expected motion error is much lower than the flat error from the specification of the rotating device. The possibility of calculating the expected motion error but also helps in the case that in the operation of the coordinate measuring machine or the machine tool

Workpiece with the rotating device to be rotated, due to his

Properties (in particular its shape) a determined favorable working position and / or work orientation of the coordinate measuring device or the

Machining tool does not allow or in which the measurement or machining of the workpiece in the favorable working position and / or work orientation is not of interest. It can therefore be an available one without re-measurement of motion errors and / or with regard to the measurement task or processing task meaningful favorable working position and / or work orientation can be determined.

In particular, by calculating the expected motion error, the difference of the motion error to a work position and / or work orientation in which the motion error was measured can be calculated. Another possibility is to _" find a list of favorable working positions and / or work orientations, with the expected motion error increasing or not decreasing in the order of the list. The first entry in the list therefore concerns one

Work position and / or work orientation for which the expected motion error is smallest within the examined range of the turning device. If for the execution of a measuring task for the measurement of a workpiece or a

Machining task for machining a workpiece one or more

Working positions and / or work orientations in the order of the list are not possible, from the list the next possible favorable working position and / or work orientation can be determined.

From the calculation of the expected motion error, however, it is also possible to estimate how great the uncertainty of the expected motion error is, because the favorable working position and / or work orientation can not be set exactly during the execution of a measuring task or machining task. For example, it can be estimated how exactly the working position and / or working orientation can be adjusted and by what amount the expected movement error thereby changes.

In the determination of the filtered expected error values, the results of the measurement of the movement error of the rotating device (in particular for an axial position) as a function of the rotational position over a complete revolution or a part of a rotation of the rotary device about the axis of rotation can be determined _» eg by a Fourier transform are transformed into the frequency space according to which at least a predetermined range of the number of waves are filtered (eg by a bandpass filter) and transformed back into the space of the rotational position values. In this way, the filtered expected error values are now available, one for each of the plurality of relative ones

Working positions and work orientations. An assigned working position corresponds to the axial position at which the function as a function of the rotational position a full round or part of a round was determined. It is a realization of the present invention that the filtered ones are expected

Generally, error measurement values for each combination of a working position with a work orientation (i.e., for each particular arrangement of a coordinate measuring device or a machining tool) will differ from all other such combinations, or almost any other such combination.

Regardless of the embodiment of the filtering, the filtering has the advantage that the filtered expected error values and thus the output data for determining the favorable working position and / or work orientation essentially only

Have error portions in the at least one predetermined range of orders. The favorable working position and / or work orientation is therefore determined in relation to the at least one predetermined range. A range of orders is also understood to mean an area containing only a single order (eg, order 3).

In particular, it is possible to filter the error measurement values not only once in the manner described above, but several times, with the unfiltered error measurement values being assumed in particular for each filtering. Therefore, it is possible to specify different predetermined ranges of orders of the ripple for the different filter processes. Different sets of filtered expected error values are obtained and, for example, a favorable working position and / or work orientation can be determined separately for each result of the filtering. In this way, it is possible, for example, to determine a favorable arrangement for a first order of the ripple (for example order three) and a favorable arrangement for a second order of the ripple (for example order four). Since the favorable working positions and / or working orientations for the various regions of orders of waviness are generally different, this results in that a measurement of a workpiece with the coordinate measuring device is performed with different arrangement of the coordinate measuring device, wherein each of the arrangements the measurement of waviness in a different range of orders of waviness is favorable.

In particular, it is possible for a working position and / or working orientation calculated from the filtered expected error values to be the error contribution of the Motion error of the rotating device with respect to the at least a predetermined range of the order of ripple indicate. Furthermore, for the calculated

Work position and / or work orientation from the error measurements also the

Total motion errors are determined and consequently also the error contribution of the motion error outside the at least one predetermined range of the order of the ripple. Each of these details is a quality measure for the measurement or

Machining the workpiece.

The predetermined range or one of the predetermined ranges of the number of waves over a complete revolution or a part of one revolution of the rotational movement may also have only one wavenumber, i. an order {see above} included. This is e.g. then advantageous if the maximum allowable error for a measurement task or

Machining task of a workpiece in this order is particularly small.

Usually in ripple analyzes of rotationally symmetrical workpieces, the ripple error as a function of the order of the ripple is compared with an error limit function, which also depends on the order of the ripple. This error limit function corresponds to the predetermined maximum allowed error. In particular, the amplitude of the ripple is used as the error measure. The amplitude thus corresponds to the maximum fluctuations of the measured value of a hypothetical or actual sensor, which measures the radial position of the workpiece with respect to the axis of rotation over one revolution of the rotary device.

In particular, from the filtered expected error values, a working position and / or working orientation can be determined for which the expected error value is less than or, in an alternative case, less than or equal to the predetermined maximum permitted limit value. The invention has the advantage that different

Working positions and / or working orientations of the coordinate measuring device or the machining tool can be evaluated to see whether the associated filtered expected error value meets the predetermined condition. The measurement of the rotational movement errors of the rotary device can be carried out very quickly compared to other methods of investigation of errors of a rotating device. For example, It is sufficient if a rotationally symmetric measuring body or two

rotationally symmetric measuring body at different axial positions in each case at two measuring points, for example, have an angular distance of 90 ° about the axis of rotation, to a change in the radial position during a revolution of the measuring body or the measuring body is scanned around the axis of rotation / be. Optionally, in addition, the movement error in the axial direction of the axis of rotation can be measured, which is usually referred to as a rollover, for example, when using capacitive distance sensors can be performed a revolution of the measuring body or the measuring body within a few seconds, at a measuring frequency of eg a few kHz Variety of readings is generated, each one

correspond to different rotational position.

As mentioned, various movement errors of the rotary device can be separated according to error sources and / or separated by degrees of freedom of movement of the real

Rotary axis relative to the ideal axis of rotation measured and / or determined. From the various errors, e.g. immediate findings about favorable

Working positions and / or work orientations. But it is also possible to evaluate the expected total error of the rotating device _» eg at certain working positions and / or work orientations or in areas of the working position and / or in areas of work orientation.

In particular, it is also possible to take into account knowledge of the expected shape of the workpiece whose coordinates are to be measured in the evaluation of the expected error values and in particular the expected total error. For example, For example, the workpiece may have been produced in a known production method, which periodically allows deviations from the ideal rotationally symmetrical shape to be expected over a substantially rotationally symmetrical course of the surface of the workpiece. By simulating the measuring process of measuring the coordinates or at least parts of the measuring process, it is possible to determine a working position and / or a working orientation of the coordinate measuring device that it is

allow to determine the periodic shape deviations of the workpiece from the ideal shape with little error. For example, the measurement task may require that the locations on the surface of the workpiece for which the greatest form deviations are expected from the ideal shape can be measured with an error that is less than a predetermined limit. Alternatively, the measurement orientation with respect to the rotary device can be determined in which the periodic shape deviations can be measured with the least expected error of the rotary device. In particular, as described above, the at least one working position and / or working orientation can be determined by simulation of the coordinate measurement or machining of the workpiece. Therefore, the working position and / or work orientation is determined optimally for the respective task. The simulation can be limited to the motion errors to be expected from the axis of rotation. A workpiece,

in particular, a real workpiece with form errors, is not required for the simulation.

In particular, when determining the at least one working position and / or orientation of a work measuring object can be used as a basis _"according to which the surface of the workpiece is scanned in a scanning. The scanning (for example tactical or optical) scanning of the workpiece is frequently used, for example, for measuring approximately rotationally symmetrical surface areas and leads to measurement results in a short time. According to another object of measuring _"may be taken as a basis, coordinates of individual points are measured only at a surface of a workpiece. The measuring task can z. B. provide an optical, pneumatic, inductive, magnetic, capacitive and / or tactile antastende measurement.

The invention has the advantage that the measurement of the error of the rotary device compared to a complete calibration is simplified because expected errors are calculated from the measured errors. Therefore, the measurement of the error of the rotary device can be repeated more often, for example, every time before the measurement or machining of a workpiece.

In particular, the at least one of the filtered expected error values of the

Rotary device determined working position and / or work orientation issued by a detection device to a controller of the coordinate measuring device or the machine tool. It is possible _» that the determination device is part of the control. In this case, output to another part of the controller, which controls the measurement of the workpiece by the coordinate measuring device or the machining of the workpiece by the machine tool. In this way, a measurement of the workpiece or a machining of the workpiece can be started automatically after the determination of the at least one working position and / or work orientation. The coordinate measuring device is, for example, a probe for tactile scanning or optical scanning of the workpiece. Alternatively, it may be (for example, a measurement head) is also a sensor that is configured to generate, depending on the measurement of the workpiece signals _"from which the coordinates of the workpiece are determined. The coordinate measuring device is part of a coordinate measuring machine, for example. The machining tool of the machine tool may be, for example, a cutting tool or a grinding tool.

The scope of the invention also includes a coordinate measuring apparatus with the arrangement for reducing the error of a rotating device. In particular, the

Detection device to be connected to a controller of the coordinate measuring machine, so that the controller according to the determined at least one working position and / or working orientation of the coordinate measuring device can control a measurement of coordinates of a workpiece.

As already mentioned, the invention can be applied in the field of machine tools. Often machine tools have two rotary devices (usually referred to as spindles). The one spindle rotates the workpiece during the

Processing. The other spindle allows rotation of the machining tool. The axes of rotation of the two spindles are parallel to each other in many cases. By the invention, the tool spindle can be brought into a favorable rotational position (and thus in a corresponding work orientation) and / or in a favorable working position along the axis of rotation of the workpiece spindle.

In particular, from the determined filtered expected error values of

Turning device can be generated an error card or an error model. The map or model may e.g. stored in a data store to which the

Control of the coordinate measuring machine or machine tool has access. The difference between an error map and an error model is that in the error map the error values for the respective working positions and / or

Working orientations are deposited, while an error model at least one

The calculation rule contains information about the error values

desired working positions and / or work orientations the expected error values can be calculated. A combination of error card and error model is possible. For example, the error model may determine how to determine expected error values from error values contained in the error map for other working positions and / or work orientations. In particular, the above-mentioned further influences on the error of the rotating device, eg the weight of the workpiece, can be taken into account by different error maps and / or error models respectively assigned to the influencing factor or a combination of influencing factors. Again, a combination of error cards and error models is possible.

In particular, an error model may have information about the turning device (eg, the rigidity of the bearing of the rotatable part of the turning device) and, using this information, calculate expected turning device error values for at least one work orientation and / or working position suitable for particular, in particular given tasks are to be expected. For example, In this way, the error model can take account of the change in working conditions due to forces acting on the workpiece or on measuring the workpiece.

In particular, the control of the coordinate measuring machine or the

Machine tool with respect to the error of the rotating device favorable

Determine working orientations and / or working positions and propose them to a user. As mentioned above, the control of these favorable working positions and / or working orientations can alternatively or additionally automatically for the

Use work process.

In the field of machine tools, the invention is particularly suitable for high-speed rotary devices, in particular workpiece spindles, since at high rotational speeds no compensation of the error of the rotary device, e.g. by appropriate tracking of the machining tool, is possible.

The invention is also suitable in combination with mathematical corrections of the error of the rotating device. For example, For example, the rotary device may have been calibrated and corresponding correction values may be stored to correct the error of the rotary device, e.g. for accessing the control of the coordinate measuring machine or the

Machine tool. The method according to the invention can, in this case, taking into account the corrections, the expected residual errors for various Determine work positions and / or work orientations and use them as already described as expected errors of the rotating device.

Instead of a computational correction of the errors of the rotary device and the computational determination of the expected residual errors, the measurement of the errors of the rotary device can be carried out taking into account the corrections and the residual error can be measured in this way. From this again the expected error values can be determined.

Embodiments of the invention will now be described with reference to the accompanying drawings. The individual figures of the drawing show:

Fig. 1 is a turning device, in particular a turntable, for a

Coordinate measuring device, wherein on the rotatable part of the rotating device, a rotationally symmetric part, here a cylinder, is arranged, whose axis of symmetry coincides with the axis of rotation of the rotating device and wherein schematically a certain working position and work orientation, z. B. a sensor of a coordinate measuring device, is shown,

Fig. 2 shows the illustration of FIG. 1, wherein the work orientation and

Working position of the sensor is chosen differently than in Fig. 1,

FIG. 3 is a plan view of the arrangement in FIG. 2 for explaining the angle included by the working orientation of the sensor with a coordinate axis. FIG.

Fig. 4 shows an arrangement with a rotating device, in particular the

Turning device according to FIGS. 1 to 3, wherein a calibration body is combined with the rotating device, which has two rotationally symmetrical measuring bodies in order to measure tilting and displacements of the real axis of rotation of the rotating device relative to the ideal axis of rotation of the rotating device, a schematic representation of geometric relationships of the real and the ideal axis of rotation of a rotating device, such as the rotating device according to one of Figures 1 to 4, a diagram showing the translational error of a rotation axis with respect to a coordinate axis (eg x-axis), the vertical to the rotational axis of the rotating device and is part of a fixed coordinate system, depending on the rotation angle of the rotatable part of the rotating device relative to the fixed part of the rotating device, a diagram that the tilt error {tilt angle) of the real axis of rotation of a rotating device relative to the ideal axis of rotation of the rotating device dependent from the angle of rotation of the rotatable member relative to

fixed part of the rotating device shows, with only one

Tilting about the coordinate axis (eg y-axis) which is perpendicular to the coordinate axis (eg x-axis) with respect to which the translational error is shown in Fig. 6, ie the errors according to the representations In FIG. 6 and FIG. 7, a representation that illustrates the resulting error of the translational error shown in FIG. 6 and the rotational error shown in FIG. 7 for a complete rotation of the rotating device depending on the working position along the Turning axis represents a diagram showing the translational error of a rotating device similar to in Fig. 6, but with respect to a perpendicular, both to the rotation axis and to the first coordinate axis extending second coordinate axis as a function of the rotational position of the rotatable member, a diagram that corresponding to Fig. 7 shows the rotary error, the ve shown in Fig. 9 translational error can strengthen or compensate the translational error in a particular work orientation due to the measured in Fig. 6 and Fig. 9 shown

translational error, depending on the rotational position of the rotatable part of the rotating device, the total error of the rotating device, i. taking into account the translational errors and the rotational errors, for a first working orientation and a first working position as a function of

Rotary position of the rotatable member, the total error of the rotary device for a second working orientation and a second working position as a function of the rotational position of the rotatable member, the total error for a third working orientation and a third

Working position as a function of the angle of rotation of the rotatable part, schematically an arrangement with a rotating device, a

Measuring arrangement, a forecasting device, a detection device and a control of a coordinate measuring machine or a

Machine tool, schematically a coordinate measuring device in gantry design, on the probe a tactile probe is arranged and on the basis of a turntable is arranged, a plan view of a measuring body and a rotational position sensor of a rotational position measuring device, the displacement of the measuring body in particular from FIG. 17 in a Direction transverse to the axis of rotation of the rotating device, a measuring body of a rotational position measuring device with several possible Drehpositionsmessorten, wherein a coordinate system and angular positions are defined, Fig. 20 is an axial section through a rotating device with integrated

Rotary position measuring device.

The turning device shown in Fig. 1 comprises a rotatable part 11 _'which is rotatable relative to a non-rotatable part 12 of the rotating device around an ideal axis of rotation which in the illustration of FIG. 1 with the z-axis (eg, the vertical axis) of a Cartesian coordinate system x, y, z. However, the actual axis of rotation of the rotating device 1 1, 12 differs from the ideal axis of rotation, since the

Turning device is faulty. An embodiment of the rotary device will be explained with reference to FIG. 20.

Fig. 1 shows a arranged on the surface of the rotatable member 1 1 cylindrical part 13, the cylinder axis is aligned in the direction of the real axis of rotation of the rotating device 11, 12. For the following considerations it is assumed that the

cylindrical part 13 has no shape error, i. an ideal cylinder. When a sensor or probe of a coordinate measuring machine or analogous to a machining tool of a machine tool in the direction shown by a double-line arrow s1 is aligned with the surface of the cylindrical part 13, and when the rotatable part 1 1 of the rotating device is rotated and therefore the cylindrical part 13 rotates, the error of the rotating device, ie the deviation of the real axis of rotation from the ideal axis of rotation, to the measurement or processing. As will be explained in more detail, the error affects depending on the working position and work orientation of the probe, sensor or tool in different ways. In the case shown in Fig. 1, the working position along the z-axis of

Coordinate system x, y, z shifted by the amount Δζ upwards and runs parallel to the x-axis. As a bidirectional arrow indicates along the x-axis, the error of the rotary device 1 1, 12 may shift the circumferential surface of the cylindrical member 13 along the x-axis in both directions, i.e., in the axial direction. For a complete rotation of the rotatable member 11, the x-position of the surface portion of the portion 13 on which the stylus, sensor or tool is aligned reciprocates in the x-direction.

Fig. 2 shows the arrangement of Fig. 1, but with the working orientation changed. In the case shown, the working position is also the same as in FIG. 1 by the amount Δζ The work orientation also runs perpendicular to the z-axis, but includes an angle θ with a parallel to the x-axis. A

corresponding plan view is shown in Fig. 3.

Both in Fig. 1 and in Fig. 2 is indicated by arrows on curved lines about the x-axis and y-axis that the real axis of rotation of the rotary device about the x-axis and the y-axis tilt (ie rotate or can rotate) while the rotatable part 1 1 is rotated.

The measurement of the motion error of a rotating device, in particular the

Turning device according to Fig. 1 to Fig. 3, is shown in Fig. 4. The measuring arrangement has four measuring sensors whose measuring directions are represented by arrows which are designated by the reference symbols s2, s3, s4, s5. The measuring sensors are not shown in detail and can e.g. be attached to a common bracket 2, which is arranged on a stationary device 1. The representation in FIG. 4 is to be understood schematically. In practice, different mechanical configurations of the arrangement are possible.

The measuring sensors with the measuring directions s2, s3 are aligned with a first spherical area K1 of a calibrating body 4. The measuring sensors with the

Measuring directions s4, s5 are on a second spherical area K2 of the

Calibration body 4 aligned. In this case, the spherical areas K1, K2 are located at different axial positions along the real axis of rotation A1

Turning device 1 1, 12. From Fig. 4 it can be seen that the real axis of rotation A1 is inclined in the rotational position shown against the ideal axis of rotation A2 or skewed to this runs.

The calibration body 4 in the exemplary embodiment of FIG. 4 is a rod which extends with its longitudinal axis in the direction of the real axis of rotation A1 and has the aforementioned spherical regions K1, K2. The centers of the spherical areas K1, K2 are preferably, as the example of FIG. 4 shows, on the real axis of rotation A1. Alternative calibration bodies are possible. For example, For example, a cylindrical body, e.g. the cylindrical body 13 of FIG. 1 to FIG. 3, as

Calibration body can be used and the sensors in pairs on each be aligned different height positions (or z-positions). Preferably, the sensors are each aligned in pairs perpendicular to each other. However, this is not absolutely necessary, but facilitates the evaluation of the measurement. Furthermore, it is preferred that the measuring directions of all four measuring sensors are aligned perpendicular to the ideal axis of rotation A2. Optionally, in addition, a further measuring sensor can be used, which measures the z position of the upper part of the calibration body (in FIG. 4, ie of the first spherical region K1).

In different rotational positions of the rotatable member 1 1 relative to the fixed part 12 of the rotating device _» eg at angular intervals of 1 °, is now in the measuring directions s2 - s5 each of the distance to the spherical areas K1, K2 and / or the position of the spherical Range K1 _» K2 or its surface measured. In this way, of the four measuring sensors, the x and y components of the total error of the rotary device are measured at two different z positions. From this, the translational error and the rotational error of the rotary device can be determined. The translational error is defined by the fact that it has the same effect on the entire range of possible working positions (or the entire height, here: in the z-direction), but of the

Rotational position of the rotatable part depends. On the other hand, the rotatory error has different effects over the entire range of possible working positions. This will be discussed in more detail with reference to FIG. 5. Both the rotatory error and the translational error generally depend on the rotational position of the rotatable part 11. It follows that it is not possible to distinguish between the translational and the rotational error of the rotating device with a single measuring sensor or in a fixed working orientation. Conversely, it follows that it

Work orientations and work positions for which the translational and rotatory errors compensate better (in terms of smaller error values) than for other working positions and work orientations. This is getting even closer

received.

Furthermore, it is assumed below that the eccentricity and the tilting of the calibration body and also of the workpiece can be considered and corrected separately. It will therefore continue from an ideal rotationally symmetric

Calibration body assumed. For example, in a first step, it can be calculated from the measured values of the error of the rotating device which measurement error would have resulted at other z positions than in the measurement. For example, as described with reference to FIG. 4, the measurements were taken at the lower two z positions z1, z2 shown in FIG

carried out. FIG. 5 shows a representation in the x, z plane of the coordinate system x, y, z. The real axis of rotation A1 or its projection onto the x, z plane is inclined by the angle α relative to the ideal axis of rotation A2. Accordingly, at the position z1, e.g. a smaller deviation from the ideal situation {which exists when the

Rotational movement about the ideal axis of rotation takes place) as detected at the position z2. The difference of the error at the z positions z1, z2 is Δχ. From this, the deviation in the x-direction from the ideal situation can be calculated for a third z-position z3, as indicated in FIG. In the z position z3, the deviation from the ideal position Δχ 'is more than at the z position z1. In this way, both the deviations in the x-direction and in the analogous manner in the y-direction can be calculated for the entire relevant region in the z-direction, in accordance with the following

Equation for the deviation in the x-direction;

x2 = x1 + tan (a) ^* (z2 - z1)

In the formula, x1, x2 denote the positions in the x direction of the real axis of rotation A1 or their projection into the x, z plane, z1, z2 the z positions and α den in FIG. 5

illustrated angle between the real axis of rotation A1 and the ideal axis of rotation A2. However, the equation is valid not only for the two z-positions of the error measurements, but also for any two other z-positions, including a measurement position and a position to be calculated. The calculation of the y-positions is done in the same way by replacing y2 and x1 by y1 in the equation x2 and considering the projection of the real axis of rotation A1 on the y, z plane. Furthermore, the angle α is replaced by a corresponding angle of inclination, the

Tilting in the y, z plane describes.

In Fig. 6, for example, only the translational motion error of a rotating device in the x direction as a function of the rotational position of the rotatable member (eg, the part 1 1 in Fig. 1 to Fig. 4). As mentioned, the translational error is the same for all z positions at the respective rotational position.

As shown in Fig. 6, the translational error in the x direction fluctuates in the course of rotation of the rotatable member. Shown is an entire revolution _» as can be seen from the scaling of the horizontal axis. Along the vertical axis, the translational error components in the x direction are shown here in a range between about -5 x 10 ⁶ m to +5 x 10 ⁶ m.

The corresponding rotational error affecting the x-direction (i.e., due, for example, to a tilt of the real axis of rotation A1 alone about the y-axis) is shown in FIG

As mentioned above, the translational error does not affect the possible range of z-values differently. By contrast, the total error, which is composed of the translational and the rotational error, varies due to the analogy to the mechanical law of the lever depending on the z-position. If the work orientation can be described solely by the z-position, for example because the work alignment is always directed perpendicular to the ideal axis of rotation, the total error shown in FIG. 8 results from the translational and rotational errors shown in FIGS. 6 and 7 depending on the z position, ie depending on the working position, which can be clearly described by the z-position. The total error is given as the difference between the maximum value and the minimum value of the error over an entire revolution of the rotatable part.

It can be seen in FIG. 8 that in a range of possible z positions between 0 and 0.2 m, the total error lies between values of approximately 1 × 10 ^-6 m and 9 × 10 ^-6 m and approximately at z = 0, 12 m has its minimum. Therefore, if only the errors shown in Figs. 6 and 7 occur (ie, no errors affecting y-direction) or if the work orientation is aligned parallel to the x-axis of the coordinate system, then the recommendation is to read the working position the height or z-position 0.12 m to choose. In this working position and the aforementioned work orientation, the error of the rotating device is minimal. For determining a favorable Drehpositionsmessort.es, where the Drehpositions- measuring device, the rotational position of the rotating device with the minimum

Motion error measures. applies accordingly. However, it must be considered that the movement error in the direction tangential to the direction of rotation is responsible for the rotational position measurement error. By contrast, when the coordinate measuring device or the machining tool is aligned in the radial direction, the movement error in the radial direction is decisive. Therefore, for the

Although the rotational position measuring location selected the same working position in the z-direction, but a position which is offset in the direction of rotation by 90 ° against the location at which a radially oriented machining tool or a so-oriented coordinate measuring device would be arranged.

The case described above, were considered in the only error in the x-direction _"is now extended to the general case in which errors can also occur in the x direction or the working alignment is not always parallel to the x direction.

FIGS. 9 and 10 show dependencies of the translatory error (FIG. 9) and of the rotary error (FIG. 10), which affect one another in the y direction, corresponding to FIGS. 6 and 7. In Fig. 11, the overall translational error (ie the total error from the errors shown in Figs. 6 and 9) for a particular work orientation is shown. This total error can be calculated from the error s _x , which has an effect in the x direction, and the error s _y , which has an effect in the y direction, by the following equation:

s (f, ϋ) = s _x (φ) ^■ cos (tf) + s _y (φ) ^■ sin (tf)

In this case, 9 of the angle introduced by means of FIG. 2 and FIG

Working orientation and φ the angle of rotation of the rotatable part of the rotating device, which is also shown in the diagrams of FIGS. 6, 7, 9 and 10 and in others

Plotted along the horizontal axis. One recognizes 9 _"that the error components in the x-direction and y-direction partially offset by comparison of Fig. 11 with Fig. 6 and Fig.. In Fig. 1 1, the error values are in a smaller range than in Fig. 6 and Fig. 9. However, this depends on the selected work orientation, ie, for example, the orientation of the probe, sensor or tool relative to the rotating device. The working orientation was chosen to be θ = 45 °.

In a corresponding manner, the total rotational error can be calculated, which, like the overall translational error, depends on the working orientation, ie the angle d, and additionally depends on the working position, ie the position in the z-direction.

FIGS. 12 to 14 therefore show the dependencies of the total error of the translation errors in the x-direction and y-direction as well as the rotation in the x-direction and y-direction for only three selected pairs of working position and working orientation. Since the total rotational error of both the work orientation and the

Work position, this also applies to the total error for rotation and translation. The same applies again to the determination of a Drehpositionsmessortes. Of the

Work orientation therefore corresponds to a position in the direction of rotation, which is offset by 90 ° with respect to the axis of rotation.

The working position to the illustration in FIG. 12 is 0 in the example

Work orientation is also 0. The total error varies in a range of 8.7 μιτι. In the case of Fig. 13, the working position z = 0.144 m. The working orientation is θ = 3.3 rad. The values of the total error fluctuate over a rotation of the rotatable part of the rotating device in a range of 0.35 μιτι. For the result in Fig. 14, the working position z = 0.047 m and the working orientation Θ = 0.34 rad. The error values vary within a range of 4.7 pm.

The working position and working orientation associated with the diagram in Fig. 13 therefore leads to the least errors in one revolution of the rotatable part and would therefore be recommended in comparison of the three possible pairs of working position and working orientation.

The recommendation does not have to be made in all cases taking into account one complete revolution of the rotatable part. Rather, also measurement tasks or machining tasks conceivable according to which the rotatable part can be rotated only over a portion of a revolution. Therefore, others can

Recommendations for working position and work orientation result than for a complete turn.

Fig. 15 shows schematically an arrangement with a rotating device, for example, the rotating device according to Fig. 1 to Fig. 4. A rotatable part 1 1 of the rotating device can be rotated relative to a non-rotatable member 12. The measuring arrangement 21 is configured to measure errors of the rotary device 1 1, 12 and corresponding

Supply error measurements to a forecasting device 23. This forecasting device 23 is configured to determine from the error measurement values (in particular filtered) expected error values of the rotary device 11, 12 which are each for a relative

Working position and working orientation of a coordinate measuring device for

Determining the coordinates of the workpiece (not shown in Fig. 15) or a machining tool of a machine tool for machining the workpiece on the one hand and the rotary device on the other hand are expected. Alternatively or additionally, the prediction device is configured to determine from the error measurement values expected error values of the rotary device 1 1, 12, each for a

Drehpositionsmessort be expected. A determination device 25 is connected to the prediction device 23 and designed to determine from the expected error values of the rotary device 11, 12 at least one working position and / or working orientation for which the expected error value of the rotary device 11, 12 is favorable.

Alternatively or additionally, the determination device is designed to determine at least one favorable rotational position measurement location from the expected error values. The at least one working position and / or working orientation determined by the determining device 25 is supplied to a controller 27 of the coordinate measuring machine or the machine tool, which in particular automatically controls the measurement of a workpiece or the machining of a workpiece with the at least one determined working position and / or working orientation. Alternatively or additionally, the determined favorable Drehpositionsmessort is set.

The gantry type CMM 21 1 shown in Fig. 16 has a base 201 above the columns 202, 203 in the Z direction of a Cartesian

Coordinate system are arranged movable. The columns 202, 203 together with a cross member 204, a portal of the CMM 21 1. The cross member 204 is at its opposite ends connected to the columns 202 and 203, respectively. Electric motors not shown cause the linear movement of the columns 202, 203 in the Z direction. It is z. B. each of the two columns 202, 203 associated with an electric motor. The cross member 204 is combined with a cross slide 207, which is air bearing along the cross member 204 in the X direction of the Cartesian coordinate system movable. The instantaneous position of the cross slide 207 relative to the cross member

204 can be determined by scale graduation 206. The movement of the cross member 204 in the X direction is driven by a further electric motor.

On the cross slide 207 a vertically movable quill 208 is mounted, which at its lower end via a mounting device 210 and a rotating device

205 is connected to a coordinate measuring device 209. The

Coordinate measuring device 209 has an angled probe 215, on which a stylus 1 1 1 with probe ball 121 is removably arranged. The

Coordinate measuring device 209 can be driven by a further electric motor relative to the cross slide 207 in the Y direction of the Cartesian coordinate system. The electric motors of the CMM, the probe 209 can be moved in the area below the cross member 204 in almost any position. Further, the rotary device 205 may rotate the probe 215 about the Y-axis, so that the stylus 11 1 can be oriented in different directions.

On the base 201, there is arranged a turntable 217 (i.e., a rotating device) with an integrated rotational position sensor (not shown in Fig. 16). The arrangement is to be understood schematically. In practice, the turntable 217 will be located at a position where the stylus 1 1 1 or other stylus will hold a workpiece (not shown) disposed on the turntable 217 as freely as possible from all sides in the radial direction of the rotation axis of the turntable 217, i. in as many as you like

Working orientations, can touch. The same applies as far as possible over the entire height range along the extent of the axis of rotation of the rotating device 217 for all working positions of the stylus.

According to the preferred embodiment of the invention is initially on the

Turning device 217 a calibration such as the cylinder of FIG. 1 to FIG. 3 or the double-ball rod of FIG. 4 is arranged. Furthermore, a separate measuring device, for example as shown schematically in FIG. 4, is arranged with at least the sensors s2 to s5 and is used to compensate for the movement errors of the rotary device measure up. In this case, the sensors and also the at least one rotational position sensor of the rotary device are preferably connected to the control of the coordinate measuring machine, so that the measured values of the sensors and also of the at least one rotational position sensor can be detected by the controller and assigned to one another. Each measured rotational position corresponds to at least one measured value of one of the sensors s2 to s5. Conversely, each of the measured values of the sensors s2 to s5 is assigned to a rotational position. If only the working orientation at a fixed working position in the axial direction is to be determined, the use of two sensors, for example the sensors s2 and s3, which measure at the fixed working position is sufficient.

The control of the coordinate measuring machine can now calculate the expected error values and / or the filtered expected error values for the various working positions and / or working orientations and from this at least a favorable arrangement of the coordinate measuring device or for the use of the rotating device in

Combination with a machine tool alternatively or additionally a favorable

Determine the arrangement of a machining tool.

Alternatively or additionally, the control of the coordinate measuring machine can determine from the expected error values or from the filtered expected error values at least one favorable rotational position measuring location of the rotational position sensor of the rotary device. Not only in the case of the described here

Embodiment, but also generally with respect to the invention, the aforementioned expected variations in the radial position of the first part or the second part of the rotating device and / or variations in the position of the first part or the second part with respect to a direction tangential to the direction of rotation of

Turning device the expected error values or the filtered expected

Error values. Expected variations are expected errors.

The coordinate measuring machine in gantry design is merely an embodiment of a coordinate measuring machine whose coordinate measuring device according to the invention is to be arranged conveniently. It is therefore also coordinate measuring machines of other construction, for example gantry or articulated arm construction, can be used.

In the following, examples of rotational position measuring devices which measure the rotational position of a rotary device will be explained. For example, the rotational position measuring device be integrated into the rotating device, so that the rotational position measuring device is completely enclosed by components of the rotating device and so is protected from external influences (as z, B. Fig. 20 shows). The turning device may be, for example, a turntable, as shown in the example of FIG. 16. Alternatively, it may, for example, be a rotary joint with at least one axis of rotation.

Such hinges are used for example on coordinate measuring machines, wherein the sensor or probe of the coordinate measuring machine is connected via the rotary joint with other parts of the coordinate measuring machine, so that the rotary joint can bring the sensor or button in a desired rotational position. In particular, the rotary joint can also have two axes of rotation which run, for example, perpendicular to one another. Preferably, a rotational position measuring device is provided for each of the rotational axes.

The plan view of a rotational position measuring device in Fig. 17 shows a measuring body 75 having a plurality of line-shaped markings 82, which in the

Extend in the radial direction to an axis of rotation D of the rotating device, i. perpendicular to the axis of rotation D. Ideally, the angular spacing of the bar-shaped marks 82 is constant, e.g. at 360 marks would the

Angular distance therefore 1 °. Such an arrangement of line-shaped

Markings on a measuring body is referred to below as a partial disk. Fig. 17 also shows an X-axis and a Y-axis of a coordinate system, wherein the X-axis and the Y-axis are perpendicular to each other and each perpendicular to the

Run axis D. Furthermore, a rotational position sensor 74 is shown, which in the axial direction of the axis of rotation D above the pitch disc, that is in

Viewing direction of Figure 17 in front of the pitch disc, is arranged. In practice, more than one such sensor may be present. The optical detection range of the sensor includes one or more of the bar-shaped marks 82 simultaneously. The detection area is in particular the area with approximately five markings 82, which lie directly below the rectangular area that represents the sensor. With the rotational movement of the rotating device, the markers 82 successively pass through the detection area. The sensor 74 is disposed on a first part of the rotating device (not shown), while a second part of the rotating device, the

Particle disc has. The first and the second part of the rotating device are rotatable relative to each other about the rotation axis D. In the illustrated embodiment, the Dre position measuring location of the sensor 74 in particular the place _» on which the sensor 74th is arranged. Since the sensor 74 has a detection area on the pitch disk, which is imaged onto the sensor 74 by a projection of the pitch disk in a direction parallel to the axis of rotation, the location of the detection area may alternatively be defined as a rotational position measurement location. In each case, the coordinates of a central point of the Drehpositionsmessortes be used as coordinates of the location, for example, the point in the center of the detection area in the direction of rotation of the pitch disc in the radial distance from the axis of rotation, in the center of the

Marks 82 is located

Other designs of partial circular discs are also possible, in particular with line-shaped markings which run on the outer circumference of a disc-shaped body in a line-like manner parallel to the axis of rotation D. Further, corresponding ones

Designs, but not with linear markings, but with magnetic markings possible. In this case, the sensor 74 does not optically detect line marks, but the magnetic field that changes due to the passage of magnetic marks.

FIG. 18 shows the measuring body 75, that is to say the partial circular disk according to FIG. 17 or another partial circular disk, in two different positions. In a first position, the circular disc is designated by the reference numeral 75, in a second position by the reference numeral 75 '. However, the rotational position sensor is not to be arranged above, but radially outside the pitch disc. Four possible rotational position measuring locations of the sensor 74 are designated by reference numerals 74a, 74b, 74c, 74d. In position 75, the axis of rotation D is in the center of the pitch disc. In contrast, the pitch circle is shifted in the position 75 'by a translation vector ÄS. Due to the displacement that is the result of a movement error in the rotational movement of the rotating device, the pitch disc has translationally displaced relative to the Drehpositionsmessorten 74 a, 74 b, 74 c, 74 d in a direction which is transverse to the rotational axis D, namely in Fig. 17 and Fig. 18 perpendicular to the plane of the figure. It can be seen clearly that the displacement at the different Drehpositionsmessorten has different effects. While at the Drehpositionsmessorten 74 a, 74 b and 74 c each other completely different

Markers 82 would be detected by the sensor, depending on which position the pitch disc is located, a sensor observes at the rotational position measuring location 74d with its aligned in the direction of the rotation axis D detection area the same mark 82, regardless of where the disc is located. The shift would be in one direction within the plane of the

18, a sensor at the rotational position measuring location 74d would observe the greatest change in the position of the markers 82. This change causes the error in the measurement of the rotational position.

The example described above only clarifies the effect of a translational movement. During a rotational movement of the rotating device but find such translational movements and additional rotational movements of the

Turning device instead, as described above. Depending on the rotational position measuring location

These movements compensate or intensify in different ways. In the most favorable case, which is not to be expected in practice, however, all translational and rotational movements compensate each other

Drehpositionsmessort during a complete rotation of the rotatable part of the rotating device about the axis of rotation.

The preceding embodiments show the case that the

Particle disc or the measuring body of the rotational position measuring device rotates while the part on which the rotational position sensor is arranged, rests. However, the considerations are analogously applicable to the opposite case as well. If the rotational position sensor is moved about the axis of rotation and is thereby exposed to movement errors due to the superimposition of various translational and rotational movements, corresponding errors occur during the rotational position measurement.

Fig. 19 shows the pitch disc 75 of Figs. 17 and 18 or another

Graduated circle. Again, the pitch disc 75 is displaced relative to the axis of rotation D about the translation vector AE. Furthermore, angular positions are possible

Drehpositionsmessorte 74a, 74b, 74c of the rotational position sensor with respect to the X-axis shown. The angular position of the first rotational position measuring location 74a is zero, that is, the rotational position measuring location is on the X-axis. The second Drehpositionsmessort 74b is rotated in Umiaufrichtung the rotation axis D by the angle ß2 against the X-axis. The third rotational position measuring location 74b is rotated in the direction of rotation of the rotational axis D by the angle ßn with respect to the X-axis. At each rotational position measuring location, the sensor is aligned with the axis of rotation D. Top right is indicated by a dot in the circle that the direction of the Z-axis and thus the axis of rotation D extends perpendicular to the image plane

Furthermore, an angular distance φΜ is shown (again with respect to the X-axis), which describes the direction of the translation vector As with respect to the X-axis. By specifying the values of this angle φΜ and the magnitude of the translation vector ÄS, the translational movement in a plane perpendicular to the rotation axis D can be unambiguously described, which the pitch circle disk 75 has executed from its ideal position (in which the rotation axis D lies in the center of the pitch circle disk 75).

Fig. 19 illustrates _» that a shift of the circular disc transverse to the direction of the axis of rotation D or in another case, a displacement of the

Drehpositionsmesssensors transversely to the direction of the rotation axis D leads to a shift of the reference point of the rotational position measuring device. As a result, however, the rotational position measuring device loses the required unambiguous assignment of its

Reference point to the coordinate system of the rotating device. In Fig. 19, only the coordinate system of the rotational position measuring device is shown.

The unique geometric assignment of the coordinate systems of the rotary device on the one hand and the rotational position measuring device on the other hand can be restored in a simple manner by taking account of an angular difference with respect to the axis of rotation. Such an angular difference is also referred to as offset angle and is provided in known rotary devices with rotational position measuring devices. Now, if this location is selected after determining a favorable Drehpositionsmessortes, a corresponding offset angle can be determined and so also the required clear reference between the two coordinate systems are made. The offset angle of the rotational position measuring location is the angular difference about the rotational axis between the rotational position measuring location and the reference point of the

Rotational position measuring device (eg angle difference β2 for location 74b). The aforementioned offset angle for permanent displacement, e.g. because of a

Eccentric error can be added.

A turning device with integrated rotational position measuring device will now be described with reference to FIG. This is a particularly low-build embodiment, ie, the extension along the axis of rotation R is particularly small. The Partial disk 75 of the measuring system, which may be, for example, the partial disk according to one of the figures 17-19, is arranged at the lower end of a rod-shaped carrier 73 of the rotor 51. The rotor 51 (which may be referred to, for example, as the first part of the rotating device) is rotatably coupled to the stator 53 (which may be referred to as the second part of the rotating device, for example) via a pivot bearing 44 which is a ring bearing , Viewed from the stator 53 radially inward direction of rotation axis R, ie in an interior of the stator 53, is a Drehpositionsmessort, where a rotational position sensor 74 is disposed. The rotational position measuring location was determined in the manner according to the invention.

The construction of a rotary device shown in FIG. 20 has the advantage that the rotatable part (the rotor 51) is located predominantly above the rotary bearing 44 of the rotary device. Therefore, it is possible to measure the movement error of the rotary device by (for example, as explained with reference to FIG. 4) is placed on the rotor 51, a test specimen and measured in different rotational positions deviations from the ideal position of the specimen. Furthermore, the construction has the advantage that the measuring body of the Drehpositions- essvorrichtung (here: the

Particle disc 75) is connected to the rotor 51, but projects downwards. It can therefore be determined a favorable Drehpositionsmessort below the pivot bearing 44, although the movement error is measured only above the pivot bearing 44.

Claims

claims

1, a method for reducing errors of a rotary device (1 1, 12), which a first part (12) and a relative to the first part (12) about an axis of rotation (Ä1) of the rotating device (1 1, 12) rotatable, second Part (1 1) and a

Rotational position measuring device (74, 75) for measuring rotational positions of the first part (12) and the second part (1 1) relative to each other, wherein the rotational position measuring device (74, 75) a rotational position sensor (74) and one for the measurement the rotational position with the rotational position sensor (74)

cooperating measuring body (75), wherein the rotational position sensor (74) with the first part (12) and the measuring body (75) with the second part (1 1) is connected or vice versa, and wherein the method comprises the steps of

- Errors of the rotating device (11, 12) due to deviations between actual positions and actual orientations of the axis of rotation (A1) on the one hand and corresponding ideal positions and an ideal orientation of an ideal axis of rotation (A2) of the rotating device (1 1, 12) on the other hand are in one Range of rotation angles, ie at different rotational positions of the first part (12) and the second part

(1 1) relative to each other, measured and obtained corresponding error readings,

expected error of the radial position of the first part (12) or the second part (11) of the rotating device and / or variations of the position of the first part (12) or the second part (1 1) with respect to a direction tangential to the error measured values Direction of rotation of the rotating device, which arise due to a deviation of the rotational movement of the rotary device (11, 12) from an ideal rotational movement about the ideal axis of rotation (A2), determined for a plurality of Drehpositionsmessorten the rotational position sensor (74), where the rotational position sensor (74) Can measure the rotational position of the rotary device,

- Taking into account the expected fluctuations, at least one rotational position measuring location of the rotational position sensor (74) is determined, for which the expected fluctuations of the position with respect to the direction tangential to the direction of rotation

o are smaller than for other possible rotational position measuring points and / or o fulfill a given condition.

Method according to the preceding claim, wherein, taking into account the expected fluctuations, an angular position of the Drehpositionsmessortes is determined with respect to the axis of rotation.

Method according to one of the preceding claims _» wherein under

Taking into account the expected fluctuations an axial position of the

Drehpositionsmessortes is determined with respect to the axis of rotation.

Method according to one of the preceding claims, wherein using the turning device {1 1, 12) as part of a coordinate measuring machine {211)

Workpiece is measured by means of the coordinate measuring machine {21 1), using the rotating device (1 1, 12) as part of a machine tool, a workpiece is machined by means of the machine tool or below

Using the rotating device (1 1, 12) a workpiece is rotated, before, during and / or after the measurement of the workpiece by means of a coordinate measuring machine (21 1) or the machining of the workpiece by means of a machine tool.

Arrangement for reducing errors of a rotating device (1 1, 12), comprising a first part (12) and a second part (12) rotatable relative to the first part (12) about a rotation axis (A1) of the rotating device (11, 12) 1 1) and one

cooperating measuring body (75), wherein the rotational position sensor (74) to the first part (12) and the measuring body (75) to the second part (1 1} is connected or vice versa, and wherein the arrangement comprises: - a measuring arrangement ( 21}, which is configured _» error of the rotating device (1 1, 12} due to deviations between actual positions and actual orientations of the axis of rotation (A1) on the one hand and

corresponding ideal positions and an ideal orientation of an ideal axis of rotation (A2) of the rotary device (1 1, 12) on the other hand in one Range of angles of rotation, ie at different rotational positions of the first part (12) and the second part (1 1) relative to each other to measure and output appropriate error readings to a forecasting device (23),

- The forecast device (23) which is configured, from the error measurement expected fluctuations in the radial position of the first part (12) or the second part (1 1) of the rotating device (1 1, 12) and / or variations in the position of the first part (1) or the second part (11) with respect to a direction tangential to the rotational direction of the rotating device (11, 12), which arise due to a deviation of the rotational movement of the rotating device (1 1, 12) of an ideal rotational movement about the ideal axis of rotation (A2) for detecting a plurality of rotational position measuring locations of the rotational position sensor (74) at which the rotational position sensor (74) can measure the rotational position of the rotary device (11, 12),

- A determination device (25) which is designed to determine, taking into account the expected fluctuations, at least one Drehpositionsmessort the rotational position sensor (74) for which the expected variations in the position with respect to the direction tangential to the direction of rotation

o are smaller than for other possible Drehpositionsmessorte and / or o meet a predetermined condition.

6. Arrangement according to the preceding claim, wherein the prediction device (23) is designed to determine, taking into account the expected fluctuations, an angular position of the Drehpositionsmessortes with respect to the axis of rotation.

7. Arrangement according to one of the two preceding claims, wherein the

Predictive device (23) is designed to determine, taking into account the expected fluctuations, an axial position of the Drehpositionsmessortes with respect to the axis of rotation.

8. Arrangement according to one of the three preceding claims, wherein the

Turning device (11, 12) part of a coordinate nmessgerats (211) for measuring a workpiece is part of a machine tool for machining a workpiece or is configured, a workpiece before, during and / or after the measurement of the workpiece by means of the coordinate measuring device (21 1) or the machining of the workpiece by means of the machine tool to rotate. Method for reducing errors of a rotary device (1 1, 12) in the determination of coordinates of a workpiece (13) or in the machining of a workpiece (13), wherein the rotary device (1 1, 12) rotates the workpiece (13) about an axis of rotation (A1) of the rotating device (1 1, 12) during the determination of the coordinates or during the machining of the workpiece (13), and wherein the method comprises the steps of:

- Errors of the rotating device (11, 12) due to deviations between actual positions and actual orientations of the axis of rotation (A1) on the one hand and corresponding ideal positions and an ideal

Alignment of the rotation axis (A2), on the other hand, are performed in a range of angles of rotation, i. at different rotational positions of two rotatable relative to each other about the axis of rotation parts of the rotating device (1 1, 12), measured and obtained corresponding error measurements,

the error measurement values filter the expected expected error values

Turning device (11, 12) determined for a plurality of relative

Working positions and working orientations of a coordinate measuring device (1 1 1) for determining the coordinates of the workpiece (13) or a machining tool of a machine tool for machining the workpiece (13) on the one hand and the rotary device (1 1, 12) are expected on the other hand, filtered over at least a predetermined range of the number of waves of deviations between actual positions and actual orientations of the rotation axis (A1) on the one hand and corresponding ideal positions and an ideal alignment of the rotation axis (A2) on the other hand over a complete revolution or a part of one revolution of a rotational movement of the rotation device (1 1, 12),

- From the filtered expected error values of the rotating device (1 1, 12) at least one working position and / or working orientation of the coordinate measuring device (1 1 1) or the machining tool is determined, for which the filtered expected error value of the rotating device (1 1, 12) in a given measurement task for determining coordinates of

Workpiece (13) or a given machining task for

Machining the workpiece (13) o is smaller than for other work positions and or

Working orientations and / or

o met a given condition.

10. The method according to the preceding claim, wherein the at least one of the filtered expected error values of the rotary device (11, 12) determined working position and / or work orientation is output to a control of the coordinate measuring device (1 1 1} or the machine tool.

1 1. A method according to one of the two preceding claims, wherein the

at least one working position and / or work orientation is determined by simulation of the coordinate measurement or machining of the workpiece (13).

12. The method according to any one of the three preceding claims, wherein in the

Determining the at least one working position and / or work orientation is based on a measuring task, according to which the surface of the workpiece (13) is scanned scanning.

13. The method according to any one of the four preceding claims, wherein according to the determined at least one working position and / or work orientation, a measurement of coordinates of a workpiece or a machining of the

Workpiece is controlled.

14. Arrangement for reducing errors of a turning device (1 1, 12) in the determination of coordinates of a workpiece (13) or in the machining of a workpiece (13), wherein the rotating device (1 1, 12) a rotational movement of the workpiece (13 ) about a rotational axis (A1) of the rotary device (1 1, 12) during the determination of the coordinates or during the machining of the workpiece (13), and wherein the arrangement comprises:

- A measuring arrangement (21) which is configured, errors of the rotating device (1 1, 12) due to deviations between actual positions and actual orientations of the axis of rotation (A1) on the one hand and

corresponding ideal positions and an ideal alignment of the

On the other hand, rotational axis (A2) in a range of rotational angles, ie at different rotational positions of two relative to each other about the axis of rotation (A1) rotationally movable parts of the rotary device (11, 12), to measure and to output corresponding error measurement values to a prediction device,

- the forecasting device (23), which is configured to determine from the error measured values filtered expected error values of the rotating device (11, 12), for a plurality of relative working positions and working orientations of a coordinate measuring device (1 11) for determining the coordinates of the workpiece (13) or a machining tool of a

Machine tool for machining the workpiece (13) on the one hand and the rotary device (11, 12) are expected on the other hand, and filtered over at least a predetermined range of the number of waves

Deviations between actual positions and actual ones

Alignments of the axis of rotation (A1) on the one hand and corresponding ideal positions and an ideal orientation of the axis of rotation (A2) on the other hand over a complete circulation or part of a revolution of a

Rotational movement of the rotating device (1 1, 12),

- A determination device (25), which is configured, from the filtered expected error values of the rotary device (11, 12) at least one

Working position and / or work orientation of the coordinate measuring device (11 1) or the machining tool to determine the filtered expected error value of the rotating device (11, 12) in a given measurement task for determining coordinates of the workpiece (13) or a predetermined Machining task for machining the workpiece (13)

o is smaller than for other job positions and / or

Working orientations and / or

o met a given condition.

15. Coordinate measuring device (21 1) with an arrangement according to claim 14.

16. Coordinate measuring machine according to claim 15, wherein the determining device is connected to a controller (27) of the coordinate measuring machine (21 1), so that the controller (27) according to the determined at least one working position and / or working orientation of the coordinate measuring device (1 1 1 ) can control a measurement of coordinates of a workpiece.