Messmaschine

Abstract

measuring machine (20) having: - at least one machine axis (30, 31, 32), wherein each machine axis (30, 31, 32) has a positioning body (40, 42, 44) which is movably mounted in a translational or rotational degree of freedom (B1, B2) along an associated guide (41, 43, 45) and can be positioned in the degree of freedom (B1, B2), wherein a first machine axis (30) has a first guide (41) and a first positioning body (40) which is movable and positionable in a translational or rotational first degree of freedom (B1), - a workpiece holder (22) configured to hold a workpiece (23), and a workpiece measuring unit (25) configured to generate at least one measuring signal (M) by touching or non-contacting the workpiece (23), wherein the workpiece holder (22) and the workpiece measuring unit (25) are movable and / or positionable relative to each other by means of the at least one machine axis (30, 31, 32), - a sensor carrier (50), - a bearing arrangement (51) designed as a loose bearing, by means of which the sensor carrier (50) is mounted on the first positioning body (40), and - a first position sensor (60) arranged on the sensor carrier (50), which is configured to detect a movement and / or a position of the sensor carrier (50) in the first degree of freedom (B1).

Description

[0001] The invention relates to a measuring machine configured to probe a workpiece using a workpiece measuring unit and thereby generate a measurement signal. Based on this measurement signal, a measured value can be determined using further sensor signals. It is generally desirable to achieve the most accurate possible measurement determination.

[0002] DE 197 11 500 A1 describes a measuring system for the automatic detection and correction of position deviations in order to carry out the measurement of components moving relative to each other without being affected by thermal influences, by assigning the scanning devices, which scan a scale or a measure for position determination, directly or indirectly to a dimension and form embodiment.

[0003] From DE 43 45 094 A1, a form measuring machine with a measuring arm is known, at the end of which a form measuring sensor is arranged. The measuring arm is arranged on a movable carriage. A reference system is formed from three normals in order to determine the position of the probe in space.

[0004] To calibrate a coordinate measuring machine using a reference body, DE 10 2008 024 444 A1 proposes to probe the reference body at several measuring points in order to determine axis error values ​​of the coordinate measuring machine of the coordinate axis to be calibrated.

[0005] A reference arrangement for a coordinate measuring machine with at least one linear axis is known from DE 10 2019 134 940 A1. Using the reference arrangement, a reference body can be moved along a guide, the reference body defining a reference point. This reference point can be recorded as a reference value.

[0006] German patent DE 10 2013 102 477 A1 describes a positioning device for a positioning table, wherein a sensor arrangement is provided for detecting the position of the positioning table. The sensor arrangement can, for example, operate optically and, for position determination, illuminate a coding plate with light and detect the light pattern generated by the coding plate in a photoreceiver and evaluate it for position determination.

[0007] DE 20 08 813 A discloses a compensation device and a compensation method for a measuring head of a measuring machine, for example to compensate for temperature-related influences. For this purpose, a temperature-related dimensional change compared to a thermally unaffected rod is determined and can be compensated in this way.

[0008] Such a procedure is also described in DE 10 2014 016 646 A1.

[0009] A temperature-compensated calibration standard according to DE 197 261 73 A1 has two rods with different coefficients of thermal expansion, fixed in one plane. Leverage is arranged on these rods, extending perpendicular to them. Due to the different coefficients of expansion of the rods, the alignment of the levers remains stable. In another embodiment, aluminum rods are fixed to a steel base plate and are in turn coupled at one end to further steel rods. This utilizes the effect that aluminum has twice the thermal expansion of steel, so that the thermal expansion of the aluminum rod approximately cancels out the thermal expansion of the steel rod and the base plate.

[0010] From DE 102 59 186 A1, a device for holding measuring instruments, for example interferometers, is known. The holder consists of a material with a very low coefficient of thermal expansion, for example glass ceramic or a metal alloy.

[0011] DE 34 47 162 A1 discloses an axial bearing for a threaded spindle with a ball which is arranged between two support surfaces oriented perpendicular to the axial direction and is mounted in a sleeve so as to roll on these support surfaces.

[0012] DE 10 2013 102 474 A1 describes a probe device for contour measurement of an object. For this purpose, a probe element is movably mounted on a carriage in one degree of freedom, whereby the carriage can be moved translationally in another degree of freedom relative to the object.

[0013] The coordinate measuring machine known from DE 10 2009 044 640 A1 has a linearly movable rotary table. The linear position of the rotary table is detected by a sensor integrated into the rotary table's axis of rotation. A probe head for probing an object to be measured is arranged on a gantry of the coordinate measuring machine. The lateral guidance of the linearly movable rotary table can be achieved by four air bearings, two of which can be configured as fixed bearings and two as floating bearings.

[0014] Based on the prior art, the object of the present invention can be considered to be to improve a measuring machine and, in particular, to increase the measuring accuracy.

[0015] This problem is solved by a measuring machine with the features of claim 1.

[0016] The measuring machine according to the present invention is configured to determine a measured value of a workpiece. For this purpose, the measuring machine has a workpiece holder for holding the workpiece and a workpiece measuring unit by means of which a workpiece can be probed either by contact or without contact and at least one measuring signal can be generated.

[0017] The workpiece measuring unit can be designed differently depending on the measuring task. For example, one type of workpiece measuring unit might have a probe that can be used to touch the workpiece. Another type of workpiece measuring unit can operate without contact and therefore incorporate one or more optical measuring devices, such as a light source and a camera. Optical measurement can be performed using transmitted or reflected light. Scanners, especially laser scanners, non-contact distance sensors, or similar devices can also be used in a workpiece measuring unit.

[0018] The measuring machine is designed to move or position the workpiece holder and the workpiece measuring unit relative to each other in order to probe the workpiece at one or more measuring points. For this purpose, the measuring machine has at least one machine axis, which can be referred to as the first machine axis. The first machine axis has a first positioning element and a first guide on which the first positioning element is movably mounted in a first degree of freedom and can be positioned in this first degree of freedom. The first degree of freedom can be translational or rotational.

[0019] To enable relative positioning between the workpiece holder or a workpiece mounted on the workpiece holder and the workpiece measuring unit, the workpiece holder or the workpiece measuring unit can be arranged directly or indirectly on the first positioning body. For example, the workpiece measuring unit can be motion-coupled with the first positioning body, while the workpiece holder is either movable relative to a machine base via another machine axis or fixed relative to the machine base. Alternatively, the first machine axis with the first positioning body can be used to move and position the workpiece holder.

[0020] The measuring machine also has a first position sensor configured to detect the relative movement and / or position between the first positioning body and the first guide. For example, a first scale can be mounted on the first guide and fixed relative to it, and the first position sensor can be mounted on the first positioning body. The position sensor and the scale can work together to detect movement and / or position of the first positioning body in the first degree of freedom.

[0021] The measuring machine according to the present invention also has a sensor carrier. The first position sensor is arranged on the sensor carrier. The sensor carrier is, in turn, mounted on the first positioning body by means of a bearing arrangement. By means of the bearing arrangement, the sensor carrier is statically mounted on the positioning body. For example, for the statically determinate mounting, six bearing points or bearing locations are provided in all spatial degrees of freedom (three translational and three rotational degrees of freedom). Preferably, a separate, individual bearing unit is provided for each spatial degree of freedom. The bearing arrangement is designed such that each degree of freedom is supported separately and without play, without, however, providing support in any other degree of freedom. Each of the spatial degrees of freedom is supported by means of a fixed bearing in that degree of freedom and by means of a floating bearing or bearing location.The sensor carrier is supported in a floating manner in all other spatial degrees of freedom. It is thus statically precisely determined and mounted without stress or floating on the first positioning body.

[0022] The stress-free or floating mounting of the sensor carrier on the first positioning body prevents stresses or torsions of the first positioning body from leading to undefined deformation of the sensor carrier and thus to an undefined position of the first position sensor. This floating mounting ensures that movements and deformations of the first positioning body each result in a movement of the sensor carrier, which can be measured. In this way, it is possible to measure the movement and / or position of the first positioning body in the first degree of freedom with high accuracy using the first position sensor.

[0023] The measuring machine can have a machine base. The machine base defines a machine coordinate system. The first guide can be fixed relative to the machine coordinate system.

[0024] In one embodiment, the first guide can be fixedly mounted on the machine base and extend from the machine base in the first degree of freedom, for example linearly. The first guide can be arranged on a guide column – preferably vertical. The first scale, with which the first position sensor, for example, interacts, can be arranged on such a guide column.

[0025] It is preferred that at least one reference sensor group, each with at least one reference sensor, is arranged on the sensor carrier. The at least one reference sensor can be a distance sensor and be configured to detect a distance and / or a change in distance relative to a measuring surface.

[0026] If a reference sensor group has several reference sensors arranged at a distance from each other, which detect the distance and / or a change in distance relative to the same measuring surface, rotational movements and / or tilting movements of the sensor carrier relative to the measuring surface can also be detected about one or more axes that are aligned parallel to the measuring surface.

[0027] The measuring surface can be a reference surface or a datum surface. In the embodiments described here, a reference surface is a measuring surface arranged immovably relative to the machine coordinate system, and a datum surface is a measuring surface movable relative to the machine coordinate system, which is arranged, for example, on a movable component (in particular, a positioning element) of one of the existing machine axes.

[0028] In one embodiment, a first reference sensor group is provided on the sensor carrier, with each reference sensor of the first reference sensor group being configured to detect a distance and / or a change in distance between the sensor carrier and a first reference surface. The first reference surface is aligned parallel to the first degree of freedom and is fixed relative to the first guide, for example, on the machine base or the guide column. The distance or change in distance is detected perpendicular to the first reference surface and thus perpendicular to the first degree of freedom. In particular, the distance or change in distance can be detected by each reference sensor of the first reference sensor group in a second degree of freedom of a second positioning body of the measuring machine.

[0029] If the first degree of freedom is a rotational degree of freedom, the first reference surface extends circumferentially around the axis of rotation of this rotational first degree of freedom. The first reference surface can be oriented parallel to the axis of rotation (axial direction) and / or radially to the axis of rotation (radial direction). A normal vector of the first reference surface can form any angle from 0° to 360° with the axis of rotation.

[0030] In one embodiment, the first reference sensor group comprises two reference sensors that are arranged at a distance from each other in the direction of the first degree of freedom and preferably along an axis extending parallel to the first degree of freedom.

[0031] Preferably, the at least one reference sensor of the first reference sensor group and the first position sensor measure in a common plane in which the first reference surface is arranged. For this purpose, for example, the first scale can be arranged in the same plane as the first reference surface.

[0032] It is also advantageous if a second reference sensor group is arranged on the sensor carrier. The second reference sensor group has at least one reference sensor configured to detect a distance and / or a change in distance of the sensor carrier to one or more measuring surfaces, in particular to a second reference surface. Preferably, the first reference surface and the second reference surface are oriented perpendicular to each other. Each reference sensor of the second reference sensor group can detect a distance and / or a translational movement of the sensor carrier perpendicular to the second reference surface. If the second reference sensor group has several reference sensors, a tilting movement about one or more axes aligned parallel to the second reference surface can also be detected.

[0033] In one embodiment, the second reference sensor group has three reference sensors arranged in a plane parallel to the at least one associated measuring surface at a distance from each other, so to speak in a triangle, such that only two of the three reference sensors are arranged along a common line.

[0034] In a preferred embodiment of the measuring machine, a second machine axis with a second positioning body and a second guide is provided. The second positioning body is movably mounted on the second guide in a translational or rotational second degree of freedom and can be positioned in this second degree of freedom. The second guide is arranged on the first positioning body. This allows, for example, the formation of a cross slide or a combined lifting-rotating axis, or similar configurations.

[0035] A second position sensor detects the movement and / or position of the second positioning body in the second degree of freedom and is arranged on the sensor carrier for this purpose. In particular, the second position sensor can work in conjunction with a second scale that is fixed relative to the second positioning body and attached to it.

[0036] The first and second degrees of freedom are distinct and can, for example, be translational degrees of freedom oriented at right angles to each other. In another embodiment, the first degree of freedom can be a translational degree of freedom and the second degree of freedom a rotational degree of freedom, or vice versa.

[0037] It is advantageous if the measuring machine also has a third machine axis with a third positioning body and a third guide. The third positioning body can be mounted on the third guide, movably parallel to the second positioning body in the second degree of freedom, and positioned in the second degree of freedom. Analogous to the second positioning body, the third guide for the third positioning body can also be arranged on the first positioning body. A third position sensor can detect the movement and / or position of the third positioning body in the second degree of freedom. For this purpose, the third position sensor is arranged on the sensor carrier. In particular, the third position sensor can work in conjunction with a third scale, which is fixed relative to the third positioning body and mounted on it.

[0038] A first reference surface can be arranged on the second positioning body and / or the third positioning body, relative to which at least one reference sensor of the second reference sensor group detects a distance and / or a change in distance. A first reference surface and the second scale present on the second positioning body and / or a first reference surface and the third scale present on the third positioning body can each be arranged in a common plane.

[0039] In an advantageous embodiment of the measuring machine, a third reference sensor group with at least one reference sensor can also be arranged on the sensor carrier. Each reference sensor of the third reference sensor group is configured to detect a distance and / or a change in distance between the sensor carrier and a second reference surface arranged on the second positioning body. Additionally or alternatively, each reference sensor of the third reference sensor group can be configured to detect a distance and / or a change in distance between the sensor carrier and a third reference surface arranged on the third positioning body.

[0040] The second reference surface and / or the third reference surface is aligned parallel to the second degree of freedom and preferably perpendicular to the first degree of freedom.

[0041] It is advantageous if each reference sensor has at least one sensor element arranged in a sensor housing. The sensor housing is attached to the sensor carrier at a mounting point. Each sensor element has a sensor surface facing the associated measuring surface (reference surface). From the mounting point to the sensor surface or to one of the sensor surfaces, the sensor housing has the same thermal expansion as the at least one component of the measuring machine that connects the mounting point on the sensor carrier and the measuring surface associated with the sensor element. This at least one component is, firstly, the part of the sensor carrier on which the mounting point is located and, optionally, if present, at least one adjoining retaining or guiding component of one of the machine axes.The sensor housing expands between the mounting point and the sensor surface by the same amount as the components or parts that connect the mounting point and the measuring surface (reference surface). In this way, thermal influences can be partially or completely eliminated. The measurement of distance or change in distance is therefore at least essentially free from thermal influences.

[0042] In one embodiment, one, several, or all reference sensors of a reference sensor group or groups may have two sensor elements, which may be referred to as the first sensor element and the second sensor element. Each sensor element is configured to detect a distance and / or a change in distance to an associated measuring surface (reference surface or reference plane), with the sensor surfaces of the first and second sensor elements of a common reference sensor being oriented in opposite measuring directions. This allows a distance between the measuring surfaces to be determined, e.g., between a reference plane and a reference plane.

[0043] In a design of a reference sensor with two sensor elements, the sensor housing can be designed in such a way that the distance between the sensor surfaces of the two sensor elements remains at least essentially constant due to thermal influences.

[0044] In a preferred embodiment, this thermal insensitivity of the sensor housing can be achieved by the sensor housing having several housing parts that are expandable relative to one another, for example, housing sleeves, which are arranged at least substantially coaxially. The longitudinal expansion of these housing parts is selected such that their expansions at least substantially cancel each other out. In particular, for this purpose, two immediately adjacent housing parts can be rigidly connected to each other at one end, while at the opposite end they are freely movable relative to each other and can therefore expand in length relative to each other due to thermal influence. The first sensor element is attached to one of the housing parts and the second sensor element to another of the housing parts.The number of housing parts connecting the first sensor element to the second sensor element can be odd; for example, there can be three housing parts. A middle housing part can have a coefficient of thermal expansion twice that of an inner housing part attached to it at one end and an outer housing part attached to it at the other end. For example, the inner and outer housing parts can be made of steel or a steel alloy, and the middle housing part can be made of aluminum or an aluminum alloy.

[0045] The measuring machine may have a control device which, for example, is designed to move or position one or more positioning bodies in the respective degree of freedom.

[0046] The control unit can also be communicatively connected to the workpiece measuring unit, so that the control unit has access to at least one measurement signal from the workpiece measuring unit. The control unit can also be communicatively connected to the at least one position sensor and the at least one reference sensor, so that the control unit also has access to at least one position sensor signal and at least one reference sensor signal. The control unit is configured to determine a measured value from the at least one measurement signal, the at least one reference sensor signal, and the at least one position sensor signal, which characterizes the workpiece at the measuring location on the workpiece where the respective at least one measurement signal was generated.The measured value can, for example, be a position in a machine coordinate system of the measuring machine, indicating a characteristic point on a surface and / or an edge. The at least one position sensor signal and the at least one reference sensor signal can be combined to achieve a higher accuracy of the measured value than would be possible with the at least one position sensor signal alone.

[0047] The bearing arrangement for supporting the sensor carrier on the first positioning body preferably has several separate bearing units, in particular six bearing units. Each bearing unit is configured to support the sensor carrier and the first positioning body in exactly one spatial direction, which can be referred to as the support or bearing direction. Each bearing unit is configured to allow relative movements perpendicular to this support or bearing direction essentially unimpeded.

[0048] In one embodiment, each bearing unit has a rolling element, for example a ball, and preferably exactly one rolling element. The rolling element is supported at one point on the sensor carrier and at another point on the first positioning body. The two support points define a straight line that preferably passes through the center point or central axis of the rolling element. The support points can be diametrically opposed to each other with respect to the center point or central axis.

[0049] It is preferred if each rolling element is arranged in an elastically deformable bearing sleeve. When a force is applied obliquely or perpendicularly to the line on which the support points are located, the rolling element of the respective bearing unit can roll or slide between the sensor carrier and the first positioning element, so that each bearing unit can only support a force along the line on which the support points are located.

[0050] In particular, the elastically deformable bearing sleeve is designed such that the static friction and / or sliding friction between the rolling element and the bearing sleeve is lower than the initial rolling resistance and / or the rolling resistance of the rolling element at the contact points. To achieve this, the bearing sleeve can be made of a suitable material, for example, a soft, porous material such as foam, which forms a material pairing with the material of the rolling element that ensures sufficiently low static and sliding friction. The rolling element is preferably made of steel or a steel alloy.

[0051] Several bearing units of the bearing arrangement can be arranged along a common first plane, such that each bearing unit has a support point in this first plane. For example, three bearing units can each have a support point in the first plane. In one embodiment, the first plane is aligned parallel to the first degree of freedom and / or the second degree of freedom.

[0052] Additionally or alternatively, several bearing units can each have a support point in a common second plane. The second plane can be oriented perpendicular to the first plane. For example, the second plane can be oriented perpendicular to the first degree of freedom.

[0053] In one direction, perpendicular to the first plane and perpendicular to the second plane, there can be one, and in particular exactly one, bearing unit. The support points of this bearing unit lie on a line that is oriented perpendicular to the first plane or perpendicular to the second plane and, for example, parallel to the first degree of freedom.

[0054] In this description, numerical prefixes such as "first," "second," or "third," etc., serve only to linguistically distinguish the objects from one another and do not imply any order or prioritization unless explicitly stated. For example, a first positioning body and a third positioning body could exist without a second positioning body being strictly necessary. The same applies to the other objects that are linguistically distinguished from one another in this way.

[0055] Advantageous embodiments of the invention will become apparent from the dependent claims, the description, and the drawing. Preferred embodiments are explained in detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 a perspective schematic representation of an embodiment of a measuring machine, Fig. 2 a schematic representation of several positioning bodies, each of which is movable in a linear degree of freedom and mounted in a guide, and of a sensor carrier which is arranged on a first positioning body by means of a bearing arrangement, Fig. 3 the schematic representation from Fig. 2 looking in a different direction, Fig. 4 a perspective view of an embodiment of the sensor carrier from the Fig. 1 and Fig. 2 in a first view, Fig. 5 the embodiment of the sensor carrier from Fig. 4 in a different perspective view, Fig. 6 a partial representation of an embodiment of the measuring machine in a section plane parallel to a first degree of freedom and perpendicular to a second degree of freedom, in which several positioning bodies as well as the sensor carrier and reference sensors arranged thereon can be seen, Fig. 7 A schematic representation of a bearing unit of the bearing arrangement for supporting the sensor carrier on a first positioning body, Fig. 8 a schematic representation of an exemplary embodiment of a reference sensor in a thermally insensitive arrangement and design, Fig. 9 and Fig. 10 each a longitudinal section through an embodiment of a reference sensor with two sensor elements, Fig. 11 a perspective view of an embodiment of a rotary table with a workpiece holder, wherein the rotary table has a first positioning body which is movable and positionable in a rotational first degree of freedom about the axis of rotation, Fig. 12 a cross-sectional view through the turntable from Fig. 11 in a section plane along the axis of rotation, Fig. 13 a schematic representation of a sensor carrier for the turntable made of Fig. 11 and Fig. 12 and Fig. 14 A schematic representation of an exemplary embodiment for the arrangement of reference sensors on the rotary table according to the Fig. 11 and Fig. 12.

[0056] Fig. Figure 1 shows a simplified perspective view of a measuring machine 20. The measuring machine 20 has a machine base 21, where a machine coordinate system KM is defined and fixed relative to the machine base 21. The machine coordinate system KM can, for example, be a Cartesian coordinate system with an X-direction, a Y-direction, and a Z-direction.

[0057] The measuring machine 20 has a workpiece holder 22 for a workpiece 23. The workpiece holder 22 can have clamping devices for clamping the workpiece 23 or other support or clamping elements. It is designed to hold the workpiece 23 during measurement and optionally to move it. For this purpose, the workpiece holder 22 can, for example, have a rotary table 24 that can be rotated about a rotary axis D.

[0058] Measuring machine 20 also has at least one workpiece measuring unit 25. In the case of the Fig. In the schematically illustrated embodiment shown in Figure 1, the measuring machine 20 can simultaneously have two different workpiece measuring units 25. Each workpiece measuring unit 25 is configured to generate at least one measurement signal M when probing the workpiece 23. Probing the workpiece 23 at a measuring point on the workpiece surface can be done by contact, for example with a tactile probe 26 of a workpiece measuring unit 25, or without contact. For non-contact probing, a workpiece measuring unit 25 can, for example, have at least one optical measuring device 27, such as a light source and a light receiver (e.g., a camera). Such an optical measuring device 27 can be shown schematically in Figure 1. Fig. 1 shown, operating in transmitted light and / or alternatively set up for measurement acquisition in reflected light. Other non-contact workpiece measuring units 25 can also be used, such as scanners, in particular laser scanners, or measuring devices that operate capacitively and / or inductively.

[0059] For the relative movement and / or relative positioning of the at least one workpiece measuring unit 25 relative to the workpiece holder 22 or a workpiece 23 held therein, the measuring machine 20 has at least one, and in the exemplary embodiment several, machine axes that can perform movement and / or positioning in one translational or rotational degree of freedom each. A machine axis can move and / or position the at least one workpiece measuring unit 25 relative to the machine base 21, or move and / or position the workpiece holder 22 or the workpiece 23 relative to the machine base 21. Such machine axes can be combined with one another as desired.

[0060] In the embodiment of the measuring machine 20 according to Fig. 1. At least two or three translational machine axes and one rotational machine axis are present. For example, a first machine axis 30 is a translational machine axis in the Z direction, a second machine axis 31 is a translational machine axis in the X direction, and a third machine axis 32 is another translational machine axis in the X direction. An exemplary fourth machine axis 33 is a rotational machine axis in a circumferential direction U about a rotary axis D. For example, the rotary axis D extends in the Z direction. In the embodiment of the measuring machine 20, the Z direction is as follows: Fig. 1 a vertical direction.

[0061] In a modified embodiment, the measuring machine 20 could also have a different combination of machine axes. For example, an additional translational machine axis in the Y direction could optionally be provided. In principle, one of the two translational machine axes in the X direction could also be omitted.

[0062] Each machine axis 30 to 33 has a guide extending in the respective degree of freedom, along which an associated positioning element can be moved and positioned. For movement and positioning, each machine axis 30 to 33 has an associated axis drive 34. The axis drives 34 are in Fig. 1 are shown only schematically in the form of a block diagram and each can have an electric motor. The axis drives 34 can be individually controlled by a control unit 35 via an assigned control signal Si (i = 1, 2, 3, ..., n). Additional drives for the at least one workpiece measuring unit 25 can also be controlled – if present – ​​by a corresponding control signal Si from the control unit 35.

[0063] The control unit 35 is also provided with at least one measurement signal M from at least one workpiece measuring unit 25. Together with other sensor values, a measured value W can be determined in the control unit 35 and, for example, displayed and / or stored and / or transmitted to an external computing or storage unit via an interface of the measuring machine 20. The measured value W can preferably represent a position value, which, in addition to determining and / or evaluating a value describing the workpiece 23, can also be used for optimized / corrected positioning of the workpiece measuring unit 25.

[0064] The measuring machine 20 can have a guide column 39 that projects away from the machine base 21, for example in the Z-direction. The Z-direction can be vertically oriented in the operating position of the measuring machine 20.

[0065] In the exemplary embodiment, the first machine axis 30 has a first positioning body 40, which is mounted in a first translational degree of freedom B1 along a first guide 41 so as to be movable and positionable ( Fig. 1-3 and 6). Similarly, the second machine axis 31 has a second positioning body 42, which is mounted so that it can be moved and positioned along a second guide 43 in a translational second degree of freedom B2. The third machine axis 32 has a third positioning body 44, which is mounted so that it can be moved and positioned along a third guide 45 in a translational second degree of freedom B2.

[0066] The first guide 41 is, for example, fixed relative to the machine base 21 or the machine coordinate system KM on the guide column 39.

[0067] In this embodiment, the first degree of freedom B1 is oriented in the Z-direction, while the second degree of freedom B2 is oriented in the X-direction. The second guide 43 and the third guide 45 are arranged on the first positioning body 40. The second positioning body 42 and the third positioning body 44 each carry a workpiece measuring unit 25, which can thus be moved and positioned relative to the machine base 21 in the first degree of freedom B1 and the second degree of freedom B2, respectively.

[0068] The measuring machine 20 has a sensor carrier 50 which is mounted on the first positioning body 40 via a bearing arrangement 51 ( Fig. 2-6). The bearing arrangement 51 is configured to statically mount the sensor carrier 50 on the first positioning body 40. The position of the sensor carrier 50 relative to the first positioning body 40 is therefore defined in all degrees of freedom in the machine coordinate system KM. For this purpose, the bearing arrangement 51 has several, and for example six, bearing points or bearing locations between the first positioning body 40 and the sensor carrier 50, each bearing point or bearing location being formed by a bearing unit 52 of the bearing arrangement 51. The bearing units 52 are located in the Fig. 2 and Fig. 3 schematically represented by spheres or circles. An embodiment of a bearing unit 52 is shown in Fig. 7 shown.

[0069] Each bearing unit 52 of the bearing arrangement 51 supports the sensor carrier 50 on the first positioning body 40 in only one support direction A, i.e., in a single degree of freedom. The support direction A extends along a line G between two support points 53 of the bearing unit 52. The bearing unit 52 can only support forces acting along the line G between the support points 53. Forces acting obliquely or perpendicularly to this line G on the bearing unit 52 are not supported by the bearing unit 52.

[0070] A force-generating device (not shown) can be provided in a bearing location or in at least one of the bearing units 52 (such as an elastically compressible body and / or a spring and / or a magnet, etc.) which is configured to generate a holding force. The force-generating device can, for example, be arranged concentrically around the support direction A. The holding force can act concentrically along the support direction A. This force-generating device need not be present in every bearing location or bearing unit 52. Preferably, at least one force-generating device is provided whose holding force acts in a horizontal direction of the machine coordinate system KM, for example, a force-generating device for a holding force in the X-direction and / or a force-generating device for a holding force in the Y-direction of the machine coordinate system KM.A force generation device for a holding force in the, for example, vertical Z-direction of the machine coordinate system KM may be optionally present, but this holding force can alternatively also be generated by gravity.

[0071] In the exemplary embodiment, the bearing unit 52 has exactly one rolling element 54, which is preferably designed as a ball. The rolling element 54 bears against a support surface 55 at each support point 53. The distance between the support surfaces 55 in the support direction A, or the distance between the support points 53 in the support direction A, corresponds, for example, to the ball diameter and is, in particular, constant. The grade G extends, for example, through the center of the ball.

[0072] One support surface 55 is located on the sensor carrier 50, and the other support surface 55 is located on the first positioning body 40. The support surfaces 55 can be located on a separate support body or be an integral or monolithic component of the sensor carrier 50 or the first positioning body 40, respectively.

[0073] In the exemplary embodiment, the ball or rolling element 54 is made of steel or a steel alloy or another metallic alloy. The support surfaces 55 are preferably also made of steel or a steel alloy or a metallic alloy.

[0074] The spherical rolling element 54, for example, can roll transversely to the support direction A between the two support surfaces 55. Thus, each of the bearing units 52 allows relative movement between the sensor carrier 50 and the first positioning body 40 in all directions perpendicular to the respective support direction A.

[0075] As it is in Fig. As shown in Figure 7, a bearing sleeve 56 can be provided for the support of the rolling element 54. The bearing sleeve 56 surrounds the rolling element 54 in a circumferential direction by the degree G. The bearing sleeve 56 is, for example, elastic. It can be elastically deformed by the forces occurring when the spherical rolling element 54 rolls. For example, the bearing sleeve 56 can be made of a foam material. On its outer side facing away from the rolling element 54, the bearing sleeve 56 can be supported indirectly or directly on the sensor carrier 50 or on the first positioning body 40.

[0076] The material pairing between the material of the bearing sleeve 56 and the material of the rolling element 54 and / or the elasticity of the bearing sleeve 56 is selected such that the static friction and the sliding friction between the bearing sleeve 56 and the rolling element 54 are lower than the starting resistance and the rolling resistance of the rolling element 54 on the support surfaces 55. This ensures that the bearing sleeve 56 does not block the rolling of the rolling element 54 between the support surfaces 55 and, at most, only minimally influences it. The design of the bearing unit 52 is such that the rolling element 54 can always roll freely under the forces acting upon it.

[0077] As it is in Fig. As can be seen in Figure 4, the bearing units 52 of the bearing arrangement 51 are grouped. Within a group, all bearing units 52 have angles G that are aligned parallel to each other, with the support points 53 preferably arranged in two parallel planes. In a first group – for example, three bearing units 52 – the angles G extend in the Y direction. In a second group – for example, two bearing units 52 – the angles G extend in the Z direction, and in a third group – for example, a single bearing unit 52 – the angles G extend in the X direction. The number of bearing units 52 per group could also be distributed differently, but there are always exactly six bearing units in total, so that the sensor carrier 50 is statically determinate, but not overdetermined, on the first positioning body 40.

[0078] Each of the bearing units 52 of the bearing arrangement 51 forms a fixed support in the support direction A and a floating support in all directions perpendicular to the support direction A. The sensor carrier 50 is floatingly mounted on the first positioning body 40 by means of each bearing unit 52. In the event of torsion or deformation of the first positioning body 40, these deformations are not transmitted to the sensor carrier 50. Instead, due to the mounting of the sensor carrier 50, even in the case of torsion or deformation of the first positioning body 40, a defined movement of the sensor carrier 50 is effected in one or more degrees of freedom. The sensor carrier 50 is therefore always free of stress and deformation, even under external influences, especially thermal influences.

[0079] To determine the measured value W, it is necessary to know the relative position between the workpiece 23 and the workpiece measuring unit 25, which is set up for probing or measurement acquisition. Therefore, several sensors are arranged on the sensor carrier 50 to determine the position of the at least one workpiece measuring unit 25 in the machine coordinate system KM. For this purpose, each machine axis 30-32, by means of which the at least one workpiece measuring unit 25 can be positioned, is assigned a position sensor.

[0080] For example, a first position sensor 60 is provided, which is configured to detect a movement and / or a position of the sensor carrier 50 in the first degree of freedom B1. The first position sensor 60 provides the control unit 35 with a corresponding first position sensor signal P1 ( Fig. 1, Fig. 4 and Fig. 5).

[0081] In the embodiment, the first position sensor 60 works together with a first scale 61, which is arranged immovably relative to the machine coordinate system KM, for example, immovably connected to the first guide 41.

[0082] The second machine axis 31 has a second position sensor 62, which is arranged on the sensor carrier 50 and is configured to detect a movement and / or a position of the second positioning body 42 in the second degree of freedom B2. For this purpose, the second position sensor 62 can, for example, cooperate with a second scale 63, which is fixedly arranged on the second positioning body 42 ( Fig. 5).

[0083] A third position sensor 64 is associated with the third positioning body 44 and is arranged on the sensor carrier 50. The third position sensor 64 is configured to detect a movement and / or a position of the third positioning body 44 in the second degree of freedom B2. For this purpose, it can cooperate with a third scale 65, which is arranged immovably on the third positioning body 44 relative to the third positioning body 44. Fig. 5).

[0084] The second position sensor 62 provides a second position sensor signal P2 and the third position sensor 64 provides a third position sensor signal P3 for the control unit 35 ( Fig. 1) Using the first position signal P1 and the second position signal P2, the position of the second positioning body 42 can be determined, and using the first position signal P1 and the third position signal P3, the position of the third positioning body 44 can be determined in the machine coordinate system KM.

[0085] The position sensors 60, 62, 64 preferably work without contact with the respective associated scale 61 or 63 or 65, for example optically and / or electromagnetically, to detect a relative movement or a position in the respective degree of freedom B1 or B2.

[0086] To increase the accuracy of position determination, the sensor carrier 50 in the exemplary embodiment has at least one reference sensor group, each with at least one reference sensor 66. Each reference sensor 66 is preferably designed as a distance sensor, for example, as a capacitively measuring distance sensor. The at least one reference sensor 66 is configured to detect a distance and / or a change in distance between the reference sensor 66 and an associated measuring surface 75. This measuring surface 75 can be a reference surface arranged immovably in the machine coordinate system KM or a reference surface arranged immovably on a positioning body 40, 42, 44, as will be described in more detail below. Preferably, each measuring surface 75 is a planar surface in one or two spatial directions. Each measuring surface 75 can be oriented perpendicular to one of the directions X, Y, Z of the machine coordinate system KM.

[0087] In the embodiment illustrated here, a first reference sensor group 67 with at least one reference sensor 66 is arranged on the sensor carrier 50. The first reference sensor group 67 has, for example, two reference sensors 66 arranged at a distance from each other in the direction of the first degree of freedom B1 (here: Z-direction). The two reference sensors 66 of the first reference sensor group 67 are arranged here along a line that extends parallel to the first degree of freedom B1. Alternatively, they could be arranged not only in the direction of the first degree of freedom B1, but also perpendicular to it, for example in the Y-direction of the machine coordinate system KM.

[0088] The reference sensors 66 of the first reference sensor group 67 are configured to detect a distance and / or a change in distance relative to a first reference surface 68. The first reference surface 68 can be arranged immovably, either directly or indirectly, on the first guide 41, for example, on the guide column 39.

[0089] The first reference surface 68 is schematically shown in Fig. 3. In the exemplary embodiment, it is arranged in a common plane with the first scale 61, wherein this plane is aligned, for example, parallel to the first degree of freedom B1 and perpendicular to the second degree of freedom B2.

[0090] A second reference sensor group 69 is arranged on the sensor carrier 50. This group has several reference sensors 66 for each positioning body 42, 44 that is movable in the second degree of freedom B2, for example, two or three reference sensors 66 each. Each reference sensor 66 of the second reference sensor group 69 is configured to detect a distance and / or a change in distance of the sensor carrier 50 relative to a second reference surface 70 and / or to a first reference surface 71. By way of example, the reference sensors 66 of the second reference sensor group 69 are configured as tandem sensors, so that they detect a distance or a change in distance to both the second reference surface 70 and the first reference surface 71.

[0091] In the exemplary embodiment, the second reference surface 70 is arranged immovably, either indirectly or directly, on the first guide 41 and can, for example, be located on the guide column 39 ( Fig. 2 and Fig. 3).

[0092] The first reference surface 68 extends parallel to the first degree of freedom B1 and parallel to the second degree of freedom B2. It is, for example, oriented perpendicular to the Y-direction of the machine coordinate system KM.

[0093] Alternatively, the first reference surface 68 and / or the second reference surface 70 can be arranged on a reference body. The reference body can be arranged on the machine base 21 and at a distance from the guide column 39. To prevent vibrations, the reference body can be additionally supported at at least one point on the guide column 39 in a vibration-damping manner, for example by means of an elastically deformable damping element.

[0094] Each additional positioning body 42, 44, which is movably mounted on the first positioning body 40, has, for example, a first reference surface 71. The first reference surface 71 is aligned parallel to the first reference surface 68, at least when the second positioning body 42 and the third positioning body 44 are ideally positioned and aligned.

[0095] A third reference sensor group 72 is also arranged on the sensor carrier 50, comprising several, and for example two, reference sensors 66. The reference sensors 66 of the third reference sensor group 72 are configured to detect a distance and / or a change in distance of the sensor carrier 50 to a second reference surface 73 and / or a third reference surface 74. In ideal orientation, the second reference surface 73 and the third reference surface 74 are aligned parallel to the second degree of freedom B2 and, in particular, perpendicular to the first degree of freedom B1.

[0096] It should be noted here that the reference surfaces 71, 73, 74 are each located on one of the positioning bodies, for example, on the second positioning body 42 or the third positioning body 44. The orientation of the reference surfaces 71, 73, 74 can therefore be influenced by thermal or other external factors affecting, for example, the second guide 43 or the third guide 45. The aforementioned orientation of the reference surfaces 71, 73, 74 relative to the machine coordinate system KM always refers to the ideal case or the desired target orientation of these reference surfaces 71, 73, 74. If one of the positioning bodies 42, 44 tilts about one or more axes due to an external influence, the orientation of the corresponding reference surfaces 71, 73, 74 in the machine coordinate system KM also changes and deviates from the ideal orientation. This can be detected using the associated reference sensors 66.

[0097] If a reference sensor group 67, 69, 72 has several reference sensors 66 assigned to a common measuring surface 75 (reference surface or reference area), tilting movements of the sensor carrier 50 relative to this measuring surface 75 about one or more axes extending parallel to the respective measuring surface 75 can also be detected. For example, a tilting movement of the sensor carrier 50 about the Y-direction can be detected by means of the two reference sensors 66 of the first reference sensor group 67.

[0098] Within the second reference sensor group 69, several reference sensors 66 are assigned to the first reference surface 71 on the second positioning body 42, and several other reference sensors 66 are assigned to the first reference surface 71 on the third positioning body 44, with all reference sensors 66 of the second reference sensor group 69 also being assigned to the second reference surface 70. In total, the second reference sensor group 69 comprises five reference sensors 66 in the exemplary embodiment, with three collaborating with the first reference surface 71 of the second positioning body 42 and two collaborating with the first reference surface 71 of the third positioning body 44. This makes it possible to determine the distance and orientation of the sensor carrier 50 relative to the second reference surface 70 and the distance and orientation of the two first reference surfaces 71 relative to the sensor carrier 50.This allows a direct relationship to be established regarding the distance and orientation between the first reference surfaces 71 and the second reference surface 70.

[0099] In the embodiment shown here, the three reference sensors 66 assigned to the first reference surface 71 of the second positioning body 42 can detect both a tilting movement about the X-direction and a tilting movement about the Z-direction. Reference sensors 66, arranged offset from one another in the X-direction, are assigned to the first reference surface 71 of the third positioning body 44 and can detect a tilting movement of the first reference surface 71 of the third positioning body 44 about the Z-direction. The second reference sensor group 69 preferably has two reference sensors 66 for each assigned first reference surface 71, which are arranged offset from one another in at least one spatial direction of the machine coordinate system KM, or has three reference sensors 66 that are arranged offset from one another in two spatial directions of the machine coordinate system KM (for example, in a triangular arrangement).

[0100] In the third reference sensor group 72, for example, two reference sensors 66 are provided, which are arranged at a distance from each other in the X-direction, i.e., in the direction of the second degree of freedom B2. Using these reference sensors 66 of the third reference sensor group 72, the distance between the second reference surface 73 and the third reference surface 74, and thus between the second positioning body 42 and the third positioning body 44, can be determined, and a tilting movement of these reference surfaces 73, 74 about the Y-direction can be detected.

[0101] Each reference sensor 66 transmits a reference sensor signal Rj (j = 1, 2, 3, ..., m) describing the measured distance or the measured change in distance to the control unit 35 ( Fig. 1).

[0102] The control unit 35 is configured to determine the measured value W based on the measurement signal M, the position sensor signals P1 to P3, and the reference sensor signals Rj. The position signals P1 to P3 can be corrected based on the reference sensor signals Rj to enable a more accurate determination of the position of the workpiece measuring units 25 in the machine coordinate system KM.

[0103] The reference sensors 66 and the position sensors 60, 62, 64, which are assigned to a common direction in the machine coordinate system KM, measure, for example, in a common plane. For this purpose, the first scale 61 and the first reference surface 68 are arranged in a common plane. Additionally or alternatively, the second scale 63 and the first reference surface 71 on the second positioning body 42 are arranged in a common plane. Additionally or alternatively, the third scale 65 and the first reference surface 71 on the third positioning body 44 are arranged in a common plane.

[0104] Furthermore, a plane in which the second reference surface 73 extends or a plane in which the third reference surface 74 extends can be a plane of symmetry that extends centrally through the first position sensor 60 (cf. Fig. 2) A plane in which the first reference surface 68 extends preferably forms a plane of symmetry that extends centrally through the second position sensor 62 and the third position sensor 64 (see Figure 1). Fig. 3).

[0105] Each reference sensor 66 has at least one sensor element 77. Each sensor element 77 has a sensor surface 78 that faces the respective assigned measuring surface 75 and is located a short distance from it. For example, the reference sensors 66 of the first reference sensor group 67 each have exactly one sensor element 77 that cooperates with the assigned first reference surface 68.

[0106] A reference sensor 66 can also have two separate sensor elements 77. In the exemplary embodiment, all reference sensors 66 of the second reference sensor group 69 and the third reference sensor group 72 each have two sensor elements 77, which are assigned to different measuring surfaces 75 (reference surface or reference area).

[0107] An embodiment of a reference sensor 66 of the second reference sensor group 69 is shown in Fig. 9 and an embodiment for a reference sensor 66 of the third reference sensor group 72 is shown in Fig. Figure 10 shows that these reference sensors 66 each have a sensor housing 79, which is attached to the sensor carrier 50 at a mounting point 80. Specifically, the sensor housing 79 is fixed to the sensor carrier 50 exclusively at this single mounting point 80. The sensor housing 79 can expand lengthwise downstream of the mounting point 80, which can change the distance between the sensor elements 77 and the mounting point 80. The mounting point 80 is shown in the Fig. 9 and Fig. 10 represented by a dotted plane.

[0108] Starting from the mounting point 80 to an associated measuring surface 75 (reference surface or reference area) of one of the two sensor elements 77, the sensor housing 79 has a thermal linear expansion which essentially corresponds to the thermal linear expansion of the sensor carrier 50 and the adjoining components of the measuring machine (e.g. part of a guide 41, 43, 45 or a component connected thereto), so that the linear expansions essentially completely cancel each other out.

[0109] Referring to Fig. For example, the linear expansion in the Z-direction between the mounting point 80 of the reference sensors 66 of the third reference sensor group 72 and the second reference surface 73 is essentially defined by the bearing units 52, whose degrees G extend in the Z-direction and which support the sensor carrier 50 in the Z-direction. The bearing units 52 are made, for example, of steel or a steel alloy and have a corresponding coefficient of linear expansion. The sensor housing 79 of each reference sensor 66 of the third reference sensor group 72 is also made of steel or the steel alloy corresponding to the bearing units 52 between the mounting point 80 and the sensor element 77 associated with the second reference surface 73, so that the magnitude of the linear expansion from the mounting point 80 to this sensor element 77 is the same.If the material expands due to heating, the distance between the two support points 53 increases, thereby increasing the distance between the mounting point 80 and the second reference surface 73. The sensor housing 79 expands to the same extent from the mounting point 80 to the sensor element 77, which is associated with the second reference surface 73, so that the thermal expansion in the Z-direction with respect to the second reference surface 73 is compensated.

[0110] The same applies to the reference sensors 66 of the first reference sensor group 67, whose sensor housing 79 between a mounting point 80 and the (single) sensor element 77 is made essentially of the same steel or steel alloy as the bearing unit 52, which supports the sensor carrier 50 in the X direction on the first positioning body 40.

[0111] At the in Fig. In the embodiment of the reference sensor 66 of the second reference sensor group 69 shown in Figure 9, the length between the mounting point 80 and the second reference surface 70 corresponds to the material from which the sensor carrier 50, the first positioning element 40, and the first guide 41 are made, which are connected to one another between the mounting point 80 and the second reference surface 70. In this embodiment, these materials can be, for example, steel or a steel alloy for the first guide 41 and aluminum or an aluminum alloy for the sensor carrier 50 and at least parts of the first positioning element 40.The sensor housing 79 of the reference sensor 66 of the second reference sensor group 69 is constructed between the mounting point 80 and the sensor element 77 assigned to the second reference surface 70 from a material that has the same coefficient of thermal expansion as the material combination of the sensor carrier 50, the first positioning body 40 and the first guide 41 between the mounting point 80 and the second reference surface 70. Here, for example, the same materials can be used proportionally and the sensor housing 79 can also be constructed from a combination of aluminum or an aluminum alloy and steel or a steel alloy.Due to thermal expansion, the distance between the mounting point 80 and the second reference surface 70 increases, whereby the sensor housing 79 between the mounting point 80 and the sensor element 77 expands to the same extent, so that the relative position between the second reference surface 70 and the sensor element 77 cooperating with it remains the same, at least essentially, regardless of thermal influences.

[0112] In the embodiments of the reference sensors 66 according to the Fig. 9 and Fig. The sensor housing 79 also comprises several housing parts, for example, three housing parts 81, 82, 83 each, which are connected to each other in such a way that they can undergo thermal length changes relative to each other. The housing parts 81, 82, 83 can be tubular or sleeve-shaped. They can, for example, be arranged coaxially to each other. Alternatively, they can also be arranged and / or connected to each other in another way so that they at least predominantly or completely compensate for thermal influences.

[0113] The principle of this nested structure of the housing parts 81, 82, 83 is highly schematic and only serves to illustrate the functional principle in Fig. 8 illustrates this. Fig. Figure 8 schematically represents aluminum or an aluminum alloy as a material for a housing part by a cross-hatched area, and steel or a steel alloy as a material for a housing part by a dotted area. The coefficient of thermal expansion of aluminum or the aluminum alloy is twice that of steel or the steel alloy. Instead of aluminum and steel, other material combinations could also be used whose coefficients of thermal expansion are essentially in a 2:1 ratio.

[0114] One of the sensor elements 77 is attached at one end to an outer housing part 81. The end opposite to this outer housing part 81 in the direction of extension is fixedly connected at a first connection point 84 to an adjacent end of a middle housing part 82. On the opposite side in the direction of extension, the middle housing part 82 is fixedly connected at a second connection point 85 to an inner housing part 83. Extending from this second connection point 85, the inner housing part 83 extends to an opposite end, to which the other sensor element 77 of the reference sensor 66 is attached. The three housing parts 81, 82, 83 are connected to each other only at the two connection points 84, 85 and can otherwise lengthen or shorten relative to each other due to thermal influence, thus moving relative to each other in pairs in a telescopic manner.

[0115] The middle housing part 82 has a coefficient of thermal expansion approximately twice as large as that of the outer housing part 81 and the inner housing part 83. Therefore, thermal influences are at least substantially compensated by the three housing parts 81, 82, 83, so that the total length L of the reference sensor 66 from the sensor surface 78 of one sensor element 77 to the sensor surface 78 of the other sensor element 77 does not change, or only changes insignificantly, due to thermal influences.

[0116] This is based on Fig. The principle described in section 8 can be applied to all reference sensors 66 that have two sensor elements 77.

[0117] Optionally, at least one damping element can be arranged in a gap and / or opening between any two relative movable parts of the sensor housing 79, for example, to dampen the relative movement of any two housing parts 81, 82, 83. For example, a flowable damping material can be introduced into a gap and / or opening and cured. The cured damping material or damping element allows relative movement of the respective housing parts 81, 82, 83 relative to each other, but provides elastic damping. The damping material or damping element can, for example, consist of silicone. For example, the at least one damping element and / or damping material E can be attached to the Fig. 9 and Fig. The at least one damping element and / or damping material E can be arranged at the specified locations marked in the 10 diagrams. Additionally or alternatively, it can also be arranged or inserted at one or more other positions. The sensor housing 79 can have corresponding externally accessible openings for this purpose.

[0118] In the previous embodiments, the degrees of freedom B1 and B2 are translational degrees of freedom. One of the degrees of freedom, and for example the first degree of freedom B1, can also be a rotational degree of freedom. This can be explained using the example of a machine axis 90 of the measuring machine 20 designed as a rotary machine axis, as illustrated by the Fig. Figures 11-14 illustrate this. Such a rotary machine axis 90 can be used for moving and positioning the workpiece holder 22 and / or for moving and positioning a workpiece measuring unit 25 in the measuring machine 20.

[0119] The rotary machine axis 90 has a positioning body 91 that can be rotatably driven in a circumferential direction U about a rotational axis D and which can, for example, be ring-shaped or plate-shaped. The positioning body 91 can also have any other geometric shape. It does not have to be closed in the circumferential direction U about the rotational axis D.

[0120] In the exemplary embodiment, the positioning body 91 is driven via an associated axis drive 34, which can, for example, be designed as a direct drive ( Fig. 12).

[0121] The rotary machine axis 90 has a position sensor, which can be referred to as the rotary position sensor 92. The rotary position sensor 92 is configured to detect a movement and / or a position of the positioning body 91 in the circumferential direction U around the axis of rotation D. For this purpose, it can, for example, cooperate with a ring-shaped scale 93 extending around the axis of rotation D, wherein the ring-shaped scale 93 can, for example, be rotationally fixed to the positioning body 91 of the rotary machine axis 90. Fig. 12). The rotation position sensor 92 provides a rotation position signal which can be transmitted analogously to the other position signals P1-P3 of the control unit 35 ( Fig. 12) The ring scale 93 can be aligned radially and / or axially relative to the axis of rotation D. The rotation position sensor 92 can thus be arranged, for example, radially adjacent or axially adjacent to the sensor carrier 50, depending on the design of the rotary machine axis 90 and the available installation space.

[0122] The sensor carrier 50 is statically mounted on the positioning body 91 by means of the bearing arrangement 51, which in turn comprises six individual bearing units 52. In this embodiment, the sensor carrier 50 is arranged circularly or annularly and concentrically or coaxially to the axis of rotation D. The bearing arrangement 51 is also designed analogously in this embodiment to the previously described embodiments of the measuring machine 20.

[0123] The sensor carrier 50 and the bearing arrangement 51 are shown schematically in Fig. Figure 13 shows that the sensor carrier 50 is supported in one direction parallel to the axis of rotation D by means of three bearing units 52. At two approximately diametrically opposite locations, the sensor carrier 50 is supported circumferentially U and tangentially to the circumferential direction U, respectively, by one bearing unit 52 each. At one location, the sensor carrier 50 is supported perpendicularly or radially to the axis of rotation D by a single bearing unit 52. The relative position of the sensor carrier 50 relative to the positioning body 91 of the rotary machine axis 90 is therefore statically determinate, but not overdetermined. The bearing units 52 of the bearing arrangement 51 have a structure as shown in Figure 13. Fig. Figure 7 is shown, so that reference can be made to the preceding description.

[0124] Several reference sensors 66 are provided on the sensor carrier 50, wherein at least one reference sensor 66 cooperates radially to the axis of rotation D with an associated first measuring surface 75 which surrounds the axis of rotation D in a ring shape and which can be a reference surface that is not moving in the machine coordinate system KM or a reference surface arranged on another movable positioning body.

[0125] Furthermore, at least one axially measuring reference sensor 66 is arranged on the sensor carrier 50, which cooperates with an adjacent second measuring surface 75, which can be a reference surface that is stationary in the machine coordinate system KM or a reference surface arranged on a movable positioning body.

[0126] In the embodiment illustrated here, at least three axially measuring reference sensors 66 and at least three or four radially measuring reference sensors 66 are provided. The axially measuring reference sensors 66 can detect wobble errors, and the radially measuring reference sensors 66 can detect eccentric errors during the movement of the positioning body 91 about the axis of rotation D.

[0127] The invention relates to a measuring machine 20 with at least one translational or rotational machine axis for moving and / or positioning a workpiece holder 22 and a workpiece measuring unit 25 of the measuring machine 20 relative to each other. For this purpose, the at least one machine axis has a positioning body 40, 42, 44, 91 mounted on an associated guide in a translational or rotational degree of freedom B1, B2, on which a sensor carrier 50 is mounted via a bearing arrangement 51. The bearing arrangement 51 is configured to provide statically determinate mounting of the sensor carrier 50 on the positioning body 40, 91 and simultaneously ensure stress-free mounting. In this way, torsions or other deformations of the positioning body 40, 91, on which the sensor carrier is mounted, the workpiece holder 22, and the workpiece measuring unit 25, are prevented. Reference symbol list: 20 measuring machine 21 machine base 22 workpiece holders 23 workpiece 24 turntables 25 workpiece measuring unit 26 buttons 27 optical measuring device 30 first machine axis 31 second machine axis 32 third machine axis 33 fourth machine axis 34 axle drive 35 Control unit 39 Leadership pillar 40 first positioning body 41 first lead 42 second positioning body 43 second lead 44 third positioning body 45 third lead 50 sensor carriers 51 Storage arrangement 52 storage units 53 support point 54 rolling element 55 support surface 56 Bearing sleeve 60 first position sensor 61 first scale 62 second position sensor 63 second scale 64 third position sensor 65 third scale 66 Reference sensor 67 first reference sensor group 68 first reference area 69 second reference sensor group 70 second reference surface 71 first reference surface 72 third reference sensor group 73 second reference surface 74 third reference surface 75 measuring area 77 Sensor element 77 sensor area 79 Sensor housings 80 Mounting point 81 outer housing part 82 middle housing part 83 inner housing part 84 first liaison point 85 second liaison point 90° rotary machine axis 91 Positioning bodies of the rotary machine axis 92 Rotation position sensor 93 Ring scale A bearing or support direction B1 first degree of freedom B2 second degree of freedom D axis of rotation G Straight KM machine coordinate system L Length of the reference sensor M Measurement signal P1 first position signal P2 second position signal P3 third position signal RJ reference sensor signal Si control signal U circumferential direction W measured value X X-direction Y Y-direction Z Z-direction

Claims

[1] Measuring machine (20) comprising: - at least one machine axis (30, 31, 32), wherein each machine axis (30, 31, 32) has a positioning body (40, 42, 44) which is movably mounted in a translational or rotational degree of freedom (B1, B2) along an associated guide (41, 43, 45) and can be positioned in the degree of freedom (B1, B2), wherein a first machine axis (30) has a first guide (41) and a first positioning body (40) which is movable and positionable in a translational or rotational first degree of freedom (B1), - a workpiece holder (22) configured to hold a workpiece (23), and a workpiece measuring unit (25) configured to generate at least one measuring signal (M) by touching or non-contacting the workpiece (23), wherein the workpiece holder (22) and the workpiece measuring unit (25) are movable and / or positionable relative to each other by means of the at least one machine axis (30, 31, 32), - a sensor carrier (50), - a bearing arrangement (51) designed as a loose bearing, by means of which the sensor carrier (50) is mounted on the first positioning body (40), and - a first position sensor (60) arranged on the sensor carrier (50), which is configured to detect a movement and / or a position of the sensor carrier (50) in the first degree of freedom (B1). [2] Measuring machine according to claim 1, comprising a machine base (21) which defines a machine coordinate system (CM). [3] Measuring machine according to claim 2, further comprising at least one reference sensor (66) arranged on the sensor carrier (50), which is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a measuring surface (75), wherein the measuring surface (75) can be a reference surface (68, 70) that is stationary relative to the machine coordinate system (CM) or a reference surface (70, 71, 73) on a positioning body (42, 44) that is movable relative to the machine coordinate system (CM). [4] Measuring machine according to claim 3, further comprising a first reference sensor group (67) arranged on the sensor carrier (50) with at least one reference sensor (66), wherein each reference sensor (66) of the first reference sensor group (67) is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a first reference surface (68) which is aligned parallel to the first degree of freedom (B1). [5] Measuring machine according to claim 4, further comprising a first scale (61) extending in the direction of the first degree of freedom (B1), which is arranged immovably relative to the machine coordinate system (KM) and / or to the first guide (41) and which is configured to cooperate with the first position sensor (60), wherein the first scale (61) and the first reference surface (68) are arranged in a common plane or in offset, parallel planes or in planes oriented at right angles to each other. [6] Measuring machine according to claim 4 or 5, further comprising a second reference sensor group (69) arranged on the sensor carrier (50) with at least one reference sensor (66), wherein each reference sensor (66) of the second reference sensor group (69) is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a second reference surface (70), wherein the second reference surface (70) is aligned parallel to the first degree of freedom (B1) and is arranged immovably relative to the machine coordinate system (KM) and / or to the first guide (41), wherein the first reference surface (68) is aligned perpendicular to the second reference surface (70). [7] Measuring machine according to one of the preceding claims, further comprising: - a second machine axis (31) with a second guide (43) and a second positioning body (42), which is movably mounted on the second guide (43) in a translational or rotational second degree of freedom (B2) and can be positioned in the second degree of freedom (B2), wherein the second guide (43) is arranged on the first positioning body (40), - a second position sensor (62) configured to detect movement and / or position of the second positioning body (42) in the second degree of freedom (B2). [8] Measuring machine according to claim 7, further comprising: - a third machine axis (32) with a third guide (45) and a third positioning body (44), which is mounted on the third guide (45) so as to be movable in the second degree of freedom (B2) parallel to the second positioning body (42) and can be positioned in the second degree of freedom (B2), wherein the third guide (45) is arranged on the first positioning body (40), - a third position sensor (65) configured to detect movement and / or position of the third positioning body (45) in the second degree of freedom (B2). [9] Measuring machine according to claim 6 and according to one of claims 7 or 8, wherein each reference sensor (66) of the second reference sensor group (69) is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a first reference surface (71) on the second or third positioning body (42, 44). [10] Measuring machine according to claim 9, comprising a second scale (63) extending parallel to the second degree of freedom (B2) on the second positioning body (42), which is configured to cooperate with the second position sensor (62) and / or a third scale (65) extending parallel to the second degree of freedom (B2) on the third positioning body (44), which is configured to cooperate with the third position sensor (64), wherein the first reference surface (71) and the second scale (63) and / or the third scale (65) are arranged in a common plane or in offset, parallel planes or in planes oriented at right angles to each other. [11] Measuring machine according to one of claims 6 to 10, further comprising a third reference sensor group (72) arranged on the sensor carrier (50) with at least one reference sensor (66), wherein each reference sensor (66) of the third reference sensor group (72) is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a second reference surface (73) arranged on the second positioning body (42). [12] Measuring machine according to claim 8 or according to one of claims 9 or 10 in combination with claim 8, further comprising a third reference sensor group (72) arranged on the sensor carrier (50) with at least one reference sensor (66), wherein each reference sensor (66) of the third reference sensor group (72) is configured to detect a distance and / or a change in distance of the sensor carrier (50) to a third reference surface (74) arranged on the third positioning body (44). [13] Measuring machine according to one of claims 3 to 6 or according to one of claims 9 to 12, wherein each reference sensor (66) has at least one sensor element (77) arranged in a sensor housing (79), wherein the sensor housing (79) is attached to the sensor carrier (50) at a mounting point (80) and has the same thermal linear expansion from the mounting point (80) to a sensor surface of the sensor element (77) or to a sensor surface of one of the sensor elements (77) as the sensor carrier (50) and / or at least a component adjoining it of one of the machine axes (30, 31, 32) from the mounting point (80) to a measuring surface (75) associated with this sensor element (77). [14] Measuring machine according to one of claims 3 to 6 or according to one of claims 9 to 13, wherein the reference sensors (66) of at least one of the existing reference sensor groups (67, 69, 72) have two sensor elements (77) arranged in a sensor housing (79), each with a sensor surface that cooperates with different measuring surfaces (75), wherein the sensor housing (79) has several housing parts (80, 81, 82) that are movable relative to each other, the thermal expansions of which cancel each other out in such a way that the distance between the sensor surfaces of the sensor elements (77) is essentially constant. [15] Measuring machine according to one of claims 3 to 14, further comprising a control device (35) to which at least one measuring signal (M) of the workpiece measuring unit (25), at least one reference sensor signal (Rj) of a reference sensor (66) and at least one position sensor signal (P1, P2, P3) of a position sensor (60, 62, 64) are provided, wherein the control device (35) is configured to determine a measured value (W) and / or position value on the workpiece (23) from it. [16] Measuring machine according to one of claims 3 to 15, wherein a measuring surface (75), on the basis of which a distance and / or a change in distance to the sensor carrier (50) is measured in one of the spatial directions (X, Y, Z) of the machine coordinate system (KM) by means of an associated reference sensor (66), lies within a plane with a position sensor (60, 62, 64), which also detects a position in the same spatial direction (X, Y, Z) of the machine coordinate system (KM). [17] Measuring machine according to one of the preceding claims, wherein the bearing arrangement (51) for the floating support of the sensor carrier (50) on the first positioning body (40) comprises several separate bearing units (52), wherein each bearing unit (52) comprises one and preferably exactly one rolling element (54) which is supported at a support point (53) on a support surface (55) on the sensor carrier (50) and at another support point (53) on a support surface (55) on the first positioning body (40). [18] Measuring machine according to claim 17, wherein each rolling element (54) is arranged in an elastically deformable bearing sleeve (56). [19] Measuring machine according to claim 18, wherein the static friction and / or the sliding friction between the rolling element (54) and the bearing sleeve (56) is less than the starting resistance and / or the rolling resistance of the rolling element (54) between the support points (53). [20] Measuring machine according to one of claims 16 to 19, wherein several bearing units (54) each have a support point (53) arranged in a common first plane which is aligned parallel to the first degree of freedom (B1). [21] Measuring machine according to claims 16 to 20, wherein several bearing units (54) each have a support point (53) arranged in a common second plane which is oriented perpendicular to the first degree of freedom (B1). [22] Measuring machine according to claim 20 or 21, wherein at least one bearing unit (54) is provided, the support points (53) of which lie on a straight line extending perpendicular to the first plane or second plane.

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