DE102018213674A1 - Sensor assembly for coordinate measurement on a workpiece - Google Patents

Abstract

A sensor assembly (1) for coordinate measurement on a workpiece (15; 34; 40), comprising an optical or a tactile sensor (2) for coordinate measurement on a workpiece, and a magnetic sensor (13) for measuring magnetic properties of the workpiece, and method where the sensor assembly (1) is used. Furthermore, an arrangement with such a sensor assembly (1) and a method for calibrating a sensor assembly (1) are disclosed.

Description

The present invention relates to a sensor assembly for coordinate measurement on a workpiece and a use of this sensor assembly for measuring workpieces. Furthermore, the invention relates to an arrangement with the sensor assembly and a calibration standard for calibrating the sensor assembly and a method for calibrating the sensor assembly.

With coordinate measuring machines (hereinafter also referred to as CMM), the shape and position of boreholes, surfaces, bolts and other geometric elements are usually determined by probing with a probe element or by evaluating an image. The roughness of the surfaces can also be determined by appropriate additional devices on a CMM. All this information is necessary to ensure that mechanical components fit together optimally or that they can move optimally together.

With increasing population and traffic densities, the demand for more and more electromobility in many large cities is developing in order to reduce the environmental impact of combustion engines. At the same time, there is also the requirement to build electric motors as efficiently as possible and to avoid scarce and difficult-to-produce resources such as rare-earth metals wherever possible.

In order to be able to build the most efficient electric motors possible and to ensure their consistent quality, in addition to the mechanical dimensions of stator and rotor, the magnetic properties at different locations relative to the mechanics must be determined.

The object of the invention was therefore to provide a device and a method, whereby dimensional and magnetic properties of electric motors or parts thereof can be determined.

According to a basic idea of the invention, an optical or tactile sensor for coordinate measurement is added to a magnetic sensor, with which a measurement of magnetic properties of a workpiece is possible. A "magnetic sensor" is to be understood as meaning a sensor with which magnetic fields can be measured.

Furthermore, a possibility for simple and accurate calibration of such a sensor assembly is proposed.

With the invention, it is possible to determine dimensional and magnetic properties with a CMM in a measurement process and also to calibrate a sensor assembly used for this purpose simply and accurately.

The device according to the invention is suitable as a sensor for position-dependent magnetic field analysis on centrally measuring Cartesian measuring heads.

• - einen optischen oder einen taktilen Sensor zur Koordinatenmessung an einem Werkstück,
• - einen Magnetsensor zur Vermessung magnetischer Eigenschaften des Werkstücks.

The invention specifies a sensor assembly for coordinate measurement on a workpiece, comprising

• an optical or a tactile sensor for coordinate measurement on a workpiece,
• - A magnetic sensor for measuring magnetic properties of the workpiece.

An inventive sensor assembly can be coupled to a known or existing measuring head, in particular a probe, a CMM. For this purpose, an interface or coupling means can be provided which is / are compatible with an interface of the measuring head. Then, there is no need to change the probe or existing electrical connections in a CMM.

The term "workpiece" generally means an object to be measured. This item need not have been previously edited.

In one embodiment, the magnetic sensor is arranged fixed in space relative to the optical or tactile sensor on the sensor assembly. If, when the sensor assembly is coupled to a CMM, in particular a measuring head of a CMM, the sensor assembly is moved, in particular along trajectories of the CMM, then the coordinate measurement sensor and the magnetic sensor are also moved and do not change their position relative to each other.

In an embodiment, the magnetic sensor is arranged close to a measurement point or touch point of the tactile sensor. This means in particular an arrangement at a distance of 0.5 to 30 mm, 0.5 to 20 mm, preferably 0.5 to 10 mm.

The magnetic sensor may comprise a plurality of measuring elements, wherein preferably at least two of the measuring elements are adapted for measuring a magnetic property (for example the field strength) or in general for measuring the magnetic field in the same spatial direction. The measuring element may be a single Hall sensor element and / or generally an independent element Measurement information generated. If there are a plurality of measuring elements for measuring the same magnetic property and in particular in the same spatial direction, a total measurement result can be determined from the measuring information obtained per measuring element, for example by averaging the individual measuring information. The total measurement result can indicate or quantify the magnetic property in this spatial direction.

In one variant, there are at least two measuring elements per spatial direction (or axis) of a Cartesian coordinate system, which measure the magnetic field in this spatial direction. In other words, the magnetic sensor may comprise pairs of associated measuring elements for each spatial direction of the coordinate system.

At least two, but preferably all, of the measuring elements may preferably be objected to equally around or to a virtual center or generally a reference point. The measurement information present at this center point can then be calculated from the measurement information determined per measuring element, for example by averaging. The center may be a center of a tactile probe body of the sensor, for example a probing ball.

For example, an associated pair of sensing elements may measure a magnetic characteristic (eg, the field strength) in a first of three orthogonal directions, and this field strength may be averaged or otherwise appropriately calculated with respect to the distances from the midpoint to match that at To determine the magnetic field strength (herein also generally referred to simply as field strength) between the virtual center enclosed by the measuring elements. If this is carried out in several directions and in particular for each of the three orthogonal directions with correspondingly provided measuring elements, a vector of the measured magnetic property (in particular of the field strength) at the center point can be determined. This can indicate the direction of the field strength but also an amount thereof. The directions may be defined by the axes of a magnetic sensor coordinate system. It is understood that a magnetic property in the context of the present disclosure can be understood as a property of the measured magnetic field.

At least two sensing elements may include a predetermined reference point of the sensor between them, for example the above-discussed virtual center of a tactile or optical sensor.

In a further embodiment, the tactile sensor has a stylus shaft and a probe element (or else probe body), in particular a probe ball (or probing ball), and the magnetic sensor is arranged in or on the stylus shaft, or the magnetic sensor is arranged in or on the probe element , in particular fastened. The probe element is attached, for example, at the end of the Taststiftschafts. For example, the magnetic sensor may be disposed in a cavity within the stylus shaft, preferably at the end of the stylus shaft where the stylus element is disposed, or disposed in a cavity within the stylus element. In the Taststiftschaft or the probe element may thus be present a cavity in which the magnetic sensor is arranged. Another possibility is the arrangement on an outer side of the Taststiftschafts or the probe element. As described above, if the magnetic sensor is arranged in the feeler element, measuring elements thereof can be arranged around a reference point and in particular a feeler center point and enclose it, for example, between them.

In the sensor assembly according to the invention, a magnetic sensor of any measurement principle and any type can be used, wherein a plurality of different magnetic sensors is known. In a special embodiment, the magnetic sensor is a Hall sensor, in particular a 3-dimensional or 3-dimensionally detecting Hall sensor. In order to provide such a three-dimensional detection capability, a plurality of measuring elements described above, which preferably each measure in one of three mutually orthogonal spatial directions, may be provided. Furthermore, measuring elements assigned to one another in pairs may be provided for measurement in each of three mutually orthogonal spatial directions. The measuring elements can each be Hall-effect measuring elements and, for example, sensor-detect a penetration of a magnetic field (that is, if they are penetrated by a magnetic field, in particular perpendicularly generate measuring signals).

The magnetic sensor may have any known external shape, with an elongated, rod-shaped or cylindrical shape being particularly favorable.

The magnetic sensor may be electrically contacted in a more suitable manner. The sensor assembly may include electrical contacts, leads and / or electronic components of the magnetic sensor.

Furthermore, the invention also provides a coordinate measuring machine, comprising a sensor assembly as above described. The design of the coordinate measuring machine is not particularly limited, with the invention being particularly well suited for a gantry type coordinate measuring machine or horizontal arm type.

Furthermore, the invention also relates to an arrangement for calibrating a sensor assembly with a sensor assembly according to one of the preceding aspects and a calibration standard, which is adapted to generate a magnetic field with defined properties. The defined properties can be understood to be consistent, known and / or reliably measurable properties, in particular with regard to the (locally) generated flux density or field strength. Preferably, the calibration standard is set up to generate an at least partially homogeneous magnetic field. The calibration standard may include a permanent magnet material and / or an electromagnet.

In one embodiment, the calibration standard is at least partially spherical (for example as a quarter, half or full sphere) and preferably comprises a permanent magnet material. Generally, it is preferred that the calibration standard be adapted for both optical, tactile and magnetic calibration, e.g. achievable by the above training. Furthermore, as a result, preferred magnetic properties can be achieved, since the magnetic field generated therefrom or its field lines are always perpendicular to the sphere surface in an entry or exit region into or out of the sphere.

In a further embodiment, the calibration standard comprises at least one coil for generating a magnetic field, in particular as part of a so-called Helmholtz coil (that is to say as part of a pair of coils positioned concentrically and objecting to one another). As a result, a region-wise homogeneous magnetic field can be generated, into which the magnetic sensor can be moved for calibration under different spatial directions, in order to determine actual signals and compare them with desired signals generated by the homogeneous magnetic field.

The coils (or also generally the calibration standard) can also be measured tactually or optically in order to be able to infer the position or orientation of the generated magnetic field. For this purpose, the tactile or optical sensor can be used, preferably if this has already been calibrated.

In a further embodiment, a so-called comparison magnet arrangement is provided as calibration standard. This known per se arrangement comprises opposing magnets which generate a homogeneous magnetic field between them.

• - Vermessen von magnetischen Eigenschaften des Werkstücks mit dem Magnetsensor des Sensorzusammenbaus.

In a further aspect, the invention relates to a method for measuring magnetic properties of a workpiece, wherein the method uses a sensor assembly as described above, and the method comprises the steps:

• - Measuring magnetic properties of the workpiece with the magnetic sensor of the sensor assembly.

The magnetic properties are in particular magnetic field strengths, in particular in a magnetic field present on the workpiece. The magnetic field may be a permanent magnetic field or a non-permanent magnetic field, such as one generated by electrical current flow in the workpiece.

• - Vermessen von Koordinaten des Werkstücks mit dem optischen Sensor oder dem taktilen Sensor des Sensorzusammenbaus.

The method may further include the following step:

• - Measuring coordinates of the workpiece with the optical sensor or the tactile sensor of the sensor assembly.

In this variant, a dimensional measurement and a measurement of magnetic properties can be combined.

The workpiece is in particular an electric motor or a part of an electric motor. A part of an electric motor is, for example, a housing, a stator, a rotor or a winding, which may be provided on one of the aforementioned parts.

In a variant of the method, the measurement of the part of the electric motor is moved in order to generate a moving magnetic field. This is especially provided for parts that generate a permanent magnetic field. In this variant of the measurement, the magnetic sensor can remain stationary and the part can be moved, wherein the magnetic field is moved and measurements on the magnetic field can take place. In particular, a magnetic rotor can be rotated during the measurement and the rotor magnetic field can be measured. In a variant, an auxiliary magnetic field or interference magnetic field can be used, for example, by a permanent magnet or electromagnet which is additionally present in the measurement next to the part of the electric motor and which is not part of the electric motor per se. The disturbance magnetic field is in a relationship to the moving magnetic field may serve to measure the magnetic properties, as described in an example below.

In a further variant of the method, during the measurement, the workpiece, in particular a part of the electric motor, is subjected to electric current in order to generate a magnetic field. For example, current may be applied to a wire coil or coil, which may be part of the status of the electric motor, to generate a magnetic field. In particular, a winding, such as a copper wire winding, be energized. Due to the irregular nature of the winding / coil, the current flow can not be as desired. Therefore, a current flow is generated in the winding / coil, which corresponds for example to a current flow during operation of the electric motor, and it is checked whether the magnetic field generated by this current is formed as desired on the winding / coil side. Accordingly, measures can be taken to improve the winding / coil.

In yet another variant of the method, a transition from ferromagnetic material to non-ferromagnetic material on the workpiece is determined with the magnetic sensor. The ferromagnetic material may have previously been magnetized and correspondingly generate a magnetic field, and the non-ferromagnetic material has no or a weaker magnetic field, wherein the magnetic field (s) is detected by the magnetic sensor.

• - Vermessen von magnetischen Eigenschaften eines Kalibriernormals mit dem Magnetsensor des Sensorzusammenbaus.

Finally, the invention also relates to a method for calibrating a sensor assembly, wherein the sensor assembly according to one of the preceding aspects is formed and the method comprises the step:

• - Measuring magnetic properties of a calibration standard with the magnetic sensor of the sensor assembly.

The calibration standard may be a calibration standard according to any of the above examples, e.g. to a calibration standard of the above-explained arrangement. The magnetic properties may relate to a magnetic field generated by the calibration standard, and the magnetic sensor may be positioned and / or moved relative to the calibration standard to detect these characteristics. The determined measurement signals or measured values can be stored, for example, together with associated position information of the magnetic sensor, which can be determined, for example, from axis positions of the coordinate measuring machine (CMM) or by probing the calibration standard carried out with the preferably calibrated optical or tactile sensor. Thus, it can be determined in which positions which local magnetic properties (in particular a field strength vector) are determined with the magnetic sensor and this can be compared with the target properties expected at these positions for the purpose of calibration.

In the context of the calibration, a relationship between the (actual) values actually acquired by the sensor and actually expected (desired) values can generally be determined and can be determined, for example, from a comparison of calibration parameters so that future acquired (actual) values and actually expected (setpoint) values match or the (actual) values can be transformed accordingly into (setpoint) values.

This can include, for example, a transformation of a magnetic sensor coordinate system into a device coordinate system, for example by means of a transformation matrix determined as part of the calibration. The sensing elements of the magnetic sensor may, in certain embodiments, provide meaningful signals above all if they are arranged in a particular manner relative to a magnetic field (e.g., penetrated perpendicularly by the field lines). In order to achieve a desired accuracy, it is generally preferred to determine a position of the measuring elements, which is determined via the magnetic sensor coordinate system, so that their measured values can be transformed, for example, into a device coordinate system.

Additionally or alternatively, at least one of the following properties may be determined during the calibration: an origin of the magnetic sensor coordinate system, rectangular deviations of paired sensing elements of the magnetic sensor as described above, a measurement sensitivity of the magnetic sensor, and / or of the same individual measuring elements.

In a variant, the magnetic field can be used to measure the magnetic field such that a shape or spatial extension of the magnetic field (usually a toroid) can be determined. This can then be compared with a desired shape or extent. For this, the magnetic field can be measured at a minimum number of positions required for mathematically determining the expected geometric shape (e.g., seven in the toroid). In general, however, it is also possible to carry out a scanning measurement with the magnetic sensor, in which the latter continuously records measured values as part of a continuous (that is to say interruption-free) movement.

The method may further comprise measuring the calibration standard by (optical and tactile) probing with the sensor, based thereon calibrating the sensor and / or inferring magnetic properties of the calibration standard. In the first case, time and costs can be saved because one and the same calibration standard can be used for a calibration of both sensor components of the sensor assembly. In the second case, nominal values of the generated magnetic field can be determined or can be closed to them. For this purpose, for example with the tactile or optical sensor, a position and / or position of the calibration standard can be determined, for example, by individual coils of a Helmholtz coil. If this is known, an expected position and / or orientation of the generated magnetic field (or a spatial progression of its field lines) can be determined and from this, desired values can be derived for comparison with the actual measured values of the magnetic sensor at specific positions in space. In this context, it is preferred that the probing sensor is already calibrated.

In order to determine the strength of the magnetic field generated by the calibration standard, the arrangement disclosed here and the calibration method can provide an additional reference sensor which is independent of the sensor assembly and preferably arranged in a stationary manner relative to the calibration standard. This can determine the strength of the magnetic field e.g. measure as an amount of field strength or a comparable and, for example, dependent size, preferably in a homogeneous region of the generated magnetic field. The magnetic sensor may also be configured to generate measurement signals relating to the strength (for example, the magnitude of the field strength) of the magnetic field. These can then be compared with the reference sensor readings, the latter representing desired values.

In the context of the present disclosure, a probing may generally be understood as an optical or tactile probing and does not necessarily imply physical contact unless otherwise indicated or apparent.

• 1: einen erfindungsgemäßen Sensorzusammenbau;
• 2: eine erste Variante der Anordnung eines Magnetsensors;
• 3: eine weitere Variante der Anordnung eines Magnetsensors;
• 4: eine Messanordnung zur Vermessung eines Rotors eines Elektromotors mit dem erfindungsgemäßen Sensorzusammenbau;
• 5a-d: einen Messablauf zur Vermessung eines Rotors eines Elektromotors mit dem erfindungsgemäßen Sensorzusammenbau;
• 6: den Aufbau eines zu vermessenen Rotors eines Elektromotors;
• 7: einen Zusammenbau zwischen Rotor und Stator bei einem Elektromotor;
• 8: den Stator eines Asynchronmotors;
• 9a-b: das Prinzip der Einbringung von Wicklungen in einem Stator eines Elektromotors;
• 10: Stator eines Elektromotors mit verschiedenen Wicklungen in verschiedener Lage;
• 11: eine Koordinatenmessung an einem Stator;
• 12: einen Rotor mit Kupferkurzschlussläufern;
• 13: eine Detailansicht des Rotors aus 12;
• 14: ein KMG mit erfindungsgemäßem Sensorzusammenbau;
• 15: eine Teildarstellung eines Sensorzusammenbaus gemäß einem weiteren Ausführungsbeispiel;
• 16: ein Kalibriernormal einer erfindungsgemäßen Anordnung;
• 17: ein alternatives Ausführungsbeispiel für ein Kalibriernormal.

The invention will be described below with reference to exemplary embodiments. Show it:

• 1 a sensor assembly according to the invention;
• 2 a first variant of the arrangement of a magnetic sensor;
• 3 a further variant of the arrangement of a magnetic sensor;
• 4 a measuring arrangement for measuring a rotor of an electric motor with the sensor assembly according to the invention;
• 5a-d a measurement sequence for measuring a rotor of an electric motor with the sensor assembly according to the invention;
• 6 : the structure of a rotor to be measured of an electric motor;
• 7 : an assembly between rotor and stator in an electric motor;
• 8th : the stator of an asynchronous motor;
• 9a-b : the principle of introducing windings in a stator of an electric motor;
• 10 : Stator of an electric motor with different windings in different position;
• 11 a coordinate measurement on a stator;
• 12 a rotor with copper short-circuit rotors;
• 13 : a detailed view of the rotor 12 ;
• 14 a CMM with inventive sensor assembly;
• 15 a partial representation of a sensor assembly according to another embodiment;
• 16 a calibration standard of an arrangement according to the invention;
• 17 an alternative embodiment for a calibration standard.

1 shows a sensor assembly 1 , The tactile sensor 2 is in the form of a stylus, which the Taststiftschaft 3 and the probe ball 4 having. The stylus shaft 3 is on the stylus holder 5 attached, which in turn to the button-mounting cube 6 is attached. Above the mounting cube 6 is a mechanical extension 7 attached to a coupling element 8th is appropriate. The plate-shaped coupling element 8th is intended to be coupled to a measuring head of a CMM. For this purpose, three bearing cylinders 9 provided, two of which are shown, and which cooperate with counter cylinder pairs on a measuring head in the sense of a known three-point bearing.

CMMs with VAST®, VAST XT® and VAST XTR® measuring heads by Zeiss are characterized by the fact that they have a very long stylus due to the cardan design of the probe head 3 can wear, as shown here, without the stylus shaft 3 leads in deep holes to Fehlantastungen. The probe ball 4 consists of ruby and the stylus shaft 3 can be made of ceramic or carbon fiber composites, so that the magnetic fields for a in Taststiftschaft 3 3D Hall sensor remain measurable. The external influence as well as the orientation of the magnetic sensor and its gain characteristic can be calibrated in a suitable device.

The sensor assembly 1 also has the electronics box 10 on, in the electronics for the Hall sensor still shown below with reference to other figures 13 is housed. At the electronics box 6 is a plug 11 for a flexible circuit board 12 provided in the stylus shaft 3 into it and through the stylus shaft 3 continues through to the in the ball 4 or at the ball end of the stylus shaft 3 attached Hall sensor.

2 shows a variant in which the 3D Hall sensor 13 very close to the probe ball 4 within the stylus shaft 3 located in one in the stylus shaft 3 formed cavity 14 , The Hall sensor 13 changes its distance to the probe ball 4 not and is therefore relatively fixed in space or space to the Tastkugel 4 , Due to the Cartesian structure of a probe used remains the spatial distance of the Hall sensor 13 to the probe ball 4 in a measurement equal and the spatial orientation of the magnetic field sensor 13 is always the same, especially if the CMM is the commonly used gantry or horizontal arm CMM.

3 shows a variant in which the 3D magnetic field sensor 13 directly into the center of the probe ball 4 is arranged, which is a technically particularly good solution, because the magnetic field sensor 13 next to the touch point of the tactile ball 4 located. This is technically possible, since usually also as a tactile ball 4 allow used ruby balls to be drilled. The electrical connection to the electronics box 10 will be like in 2 is via a flex circuit board 12 made by the stylus shaft 3 and through the stylus holder 5 guided and after screwing the Taststiftschafts with the plug 11 is plugged in there.

The communication between the CMM control and the control and evaluation of the 3D magnetic field sensor 13 via a not-shown here line system for signal or data transmission. For example, conductive connections for information transmission and construction are usable as in DE 10 2004 048 095 A1 especially at the local ones 4 and 5 , shown.

In order to be able to transfer the large amounts of data consisting of the 3D magnetic field strengths at the sampling times better by the high dot rate, they can be compressed and placed in the times of the paths of the workpiece of the CMM. This can be done in the transmitter of the magnetic field sensor 13 sufficient memory to provide the magnetic field strengths at the sampling instants of the probe measurement system 1 store a complete train and transfer it with a time delay.

The following figures show examples for the separate or simultaneous measurement of mechanical parameters and magnetic properties as well as the combination of the results in the sense of a method according to the invention.

4 and 5a-d show the rotor 15 a Relunktanzmotors with the shaft 20 and the feather key 21 , which by its magnetic sheets 16 Pole 17 and gaps 18 has, but are not visually visible from the outside. Acting on this rotor 15 with an auxiliary magnetic field from the auxiliary magnet 19 , the bar magnet below the rotor 15 , so with a corresponding clamping between peaks both the concentricity and the position of the poles 17 and gaps 18 measurable at the same time. But also the orientation of the poles 17 and gaps 18 to the groove 22 the feather key 21 and thus to the position of a later mounted gear or angle encoder can be determined thereby. This makes it possible, for example, to optimize the control field of the necessary for the operation of this motor inverter in terms of performance and smoothness.

Next to the rotor 15 is the sensor arrangement 1 the invention positioned stationary. This picture sequence of 5a-d shows the rotor 15 of the reluctance motor during rotation. This shows that the poles 17 and gaps 18 a change of the auxiliary magnetic field from the auxiliary magnet 19 cause, as the magnetic resistance between magnetic field sensor 13 and auxiliary magnet 19 constantly changes what's from the magnetic field sensor 13 is detected. One of the poles 17 and two of the gaps 18 that this pole 17 adjacent are shown respectively.

At the sectional picture of the 6 a rotor 15 a reluctance motor can be seen that the inner shape is no longer on the round ground surface of the rotor 15 is visible when measured as a workpiece. This becomes particularly important when carrying out the measurements at different workpiece temperatures in order to conclude the change in shape in a real engine under heating. Changes in shape here have a significant influence on the feasible air gap between the rotor and stator, which in turn is very important for the possible performance of the engine itself.

It is understood that according to the invention, other rotor types with the solution presented herein are magnetic and in terms of their dimensions / positioning vermessbar, z. B. rotors with permanent magnets. Also arranged in the stator Permanent magnets can be measured accordingly.

7 shows the assembly of rotor 15 and stator 23 in the case 24 at the electric motor 45 , where the winding on the stator 23 and the holder of the magnetic sheets on the rotor 15 for reasons of visibility missing.

In 8th the principle of an asynchronous motor is shown. Shown are the stator 25 , with the stator back 26 and the copper windings 27 , Further, the rotor 28 with the short-circuit ring 29 , the short-circuit bars 30 and the rotor shaft 31 shown. Here it becomes visible that here as well the highest possible efficiency of the air gap 32 As small as possible, since the magnetic resistance in air is a multiple of the magnetic resistance of the iron sheets in the stator and rotor.

In 9a-b is shown as a winding in a stator 34 is inserted and bound. In 9a is a partially completed winding 33 ' shown (which consists of several individual windings), in 9b a complete winding 33 , This work is done in a variety of engines by a person, the copper winding 33 inserted, fastened and bent according to the requirements and then binds. This type of semi-automatic production ensures that each electric motor is wound differently and thus also provides different characteristics. To check the quality of the electric motor and the individual windings, the motor should be mounted on a CMM and the winding 33 be connected to a controllable by the control of the CMM power generator. Thus, in addition to the measurement of the mechanical dimensions, the resulting magnetic field can be measured simultaneously. Because the 3D magnetic sensor 13 is very sensitive in the stylus, the measurement can be done before the "pouring" of the winding, ie any errors can be corrected by rework. This is especially important because of incorrectly bound windings 33 Generate forces that can lead to premature failure of the engine.

In 10 is a stator 38 with different single windings 35 . 36 . 37 shown. It may be due to the direction of the windings 35 . 36 . 37 Magnetic fields generated when applying current through the windings are determined, whether the each winding 35 . 36 . 37 is at the intended position. This is achieved by depending on the current supply of the individual windings 35 . 36 . 37 and measuring the magnetic field strength and direction a comprehensive picture of the entire winding can be automatically detected.

In 11 is an adaptation of the date 34 with in the stylus 2 shown. By self-centering probing with the probe ball 4 in gaps 39 Statorbleches or self-centering scanning these gaps with simultaneous magnetic field measurement can be made directly a relation between mechanical position and stray magnetic field. With a suitable choice of the diameter of the probe ball 4 In relation to the gap width one also recognizes an overfilling of the groove with winding wire. By circular movements in the air above, below and next to the bonded winding wires, both the compliance of Störkonturen and the quality of the assembly of the wire packages can be tested.

Another application of a stylus 2 with magnetic field sensor 13 is the measurement of material transitions between and ferromagnetic non-ferromagnetic materials as here with the example of a rotor 40 with aluminum or copper short-circuiters, which in 12 is shown. After finishing the workpiece (rotor 40 ), the difference of the different materials is no longer recognizable with respect to the surface for a normal CMM.

13 shows a detailed view of the rotor 40 , By an externally applied auxiliary magnetic field or by a bias of the rotor plate 41 and the evaluation of the magnetic field, however, one can see the transitions as here between iron 42 and copper 43 recognizable and thus along the running here on an oblique cylinder calender line copper line 44 to scan.

This in 14 illustrated coordinate measuring machine (CMM) 211 in portal construction has a measuring table 201 up, over the pillars 202 . 203 are movably arranged in the Y direction of a Cartesian coordinate system. The columns 202 . 203 form together with a cross member 204 a portal of the CMM 211 , The crossbeam 204 is at its opposite ends with the pillars 202 respectively. 203 connected. Not shown electric motors cause the linear movement of the columns 202 . 203 in the Y direction, along the Y motion axis. It is z. B. each of the two columns 202 . 203 associated with an electric motor. The crossbeam 204 is with a cross slide 207 combined, which air-stored along the cross member 204 movable in the X direction of the Cartesian coordinate system. The current position of the cross slide 207 relative to the cross member 204 can be based on a scale division 206 be determined. The movement of the crossbeam 204 in the X-direction, ie along the X-motion axis, is driven by another electric motor. At the cross slide 207 is a vertically movable quill 208 stored, which at its lower end over a mounter 210 and a turning device 205 with a measuring head 209 connected is.

To the measuring head 209 is a sensor assembly according to the invention 1 coupled, as in 1 shown.

The measuring head 209 can be driven by another electric motor relative to the cross slide 207 in the Z direction, along the Z-motion axis, of the Cartesian coordinate system. By the electric motors of the CMM, the measuring head 209 in the area below the cross member 204 be moved in almost any position. Furthermore, the rotating device 205 the measuring head 209 rotate around the Z axis so that the sensor assembly 1 can be oriented in different directions. Not shown is a controller that controls the movement of the moving parts of the CMM along the axes of motion. The controller is arranged to perform one or more of the steps described in the general description part.

In 15 is a partial view of a sensor assembly 1 shown according to another embodiment. One recognizes the shortened or not completely shown Taststiftschaft 3 and a probing element arranged in the form of a probe ball 4 , The probe ball 4 has a center point 100 on, which serves as a reference point. Inside, the probe ball points 4 a not separately shown cavity in which a magnetic sensor 13 comprising a plurality of pairs associated with each other measuring elements 102 is included. More precisely, the measuring elements 102 arranged so that they are in pairs along an axis of a registered (magnetic sensor) coordinate system 104 opposite and at the same time the center 100 between them.

Every measuring element 102 is adapted to measure the magnetic field strength, which is particularly reliable in a vertical penetration through the field lines of a magnetic field succeeds (ie if one of a measuring element 102 spanned rectangular area, as in 15 shown perpendicularly penetrated by corresponding field lines). The pairwise associated measuring elements 102 each serve primarily to along one of the axes of the coordinate system 104 To measure the magnetic field strength along the axis along which they face each other.

An average value can then be formed from the field strengths measured by a pair of measuring elements, in order to determine the field strength at the center of the sphere 100 to determine. This applies at least when the pairwise associated measuring elements 102 similar to the center of the sphere 100 are complained of. Otherwise, one at the distances of the measuring elements 102 to the center of the sphere 100 adapted settlement.

In this way, along each axis of the coordinate system 104 a field strength component is calculated and from this a field strength vector in the sphere center 100 be determined. This can, for example, be assigned to a current probing point and / or at least indicate the direction of the field strength, but preferably also its magnitude.

In the case shown is the sensor assembly 1 with a tactile sensor 2 provided, but not mandatory, as well as an optical sensor 2 could be used at the measuring elements 102 are arranged in an analogous manner about a reference point.

The following are ways to calibrate the sensor assembly 1 portrayed. This is according to 16 a calibration standard 110 provided, the calibration standard 110 Part of an arrangement not shown separately according to the invention, further comprising the sensor assembly 1 for example 15 includes.

A need for calibration can result from, for example, the stem 3 and the probe 4 out 15 can not be positioned relative to one another with predictable accuracy. According to existing solutions, the probe becomes 4 for example, on the shaft 3 unscrewed, but a desired screwing is not always exactly achieved and consequently also an orientation of the probing element 4 can vary. Because the magnetic sensor 13 but stationary relative to the probing element 4 is, can be an orientation of its coordinate system 104 also vary (for example, relative to the coordinate system of the CMM). This can be determined as part of the calibration and corrected (eg mathematically by calibration parameters). Further inaccuracies may arise due to the fact that the measuring elements 102 are not positioned in the desired manner to one another and / or do not have the desired characteristics (ie sensitivity), for example with respect to a measured magnetic field strength. This can also be determined and corrected as part of the calibration.

Furthermore, it is possible in the context of calibration, a relative arrangement of magnetic sensor 13 and probe element 4 or its center 100 to be checked and corrected by calibration. For example, by tactile or optical probing the achievement of a certain Antastpunkts signaled but not there expected field strength or a field strength vector with the magnetic sensor 13 be determined. In particular, in this case, the direction of the field strength vector can be considered or a deviation thereof from an expected target state, which is due to a relative displacement of the magnetic sensor 13 and probe 4 suggesting. This can be corrected by suitable calibration parameters which, for example, match a magnetic sensor and a (tactile or optical) sensor coordinate system. In this connection, it is preferred that the tactile (or even optical) sensor 2 in itself has already been calibrated, for example, using a different calibration standard (for example, a non-magnetic calibration ball).

The calibration standard 110 is spherical and made of a permanent magnet material. In 16 the field lines of the generated magnetic field are shown schematically. These run perpendicular to the exit or entry surface, ie perpendicular to the spherical surface of the calibration standard 110 if this is the calibration standard 110 to cut.

The course of the magnetic field can be due to the spherical shape of the calibration standard 110 be known or calculated. Alternatively, this can be measured by means of a reference sensor. On the basis of such information, desired values with respect to the generated magnetic field for performing the calibration can be determined.

In particular, the calibration standard 110 also as calibration standard for the optical or tactile sensor 2 serve (for example, in the manner of a so-called Einmesskugel). In a conventional manner, the calibration standard 110 first scanned with an already calibrated reference probe to determine its spherical center, and then with the optical or tactile sensor 2 to also find ball center coordinates based on that. From the difference of the respectively determined spherical center coordinates can then calibration parameters for the optical or tactile sensor 2 be derived. Further, by measuring with the reference probe or the calibrated optical or tactile sensor 2 on the shape or the spatial course of the calibration standard 110 generated magnetic field are closed, for example, when the ball center 100 determined and a radius of the ball is known or is also determined by the sensor.

In particular, in this case, the position of the ball center 100 included axis 112 be determined to run the adjacent field lines as expected rotationally symmetric and straight. Because in the area of this axis 112 can be reliably predicted and to be detected target field lines, can be provided, the magnetic sensor 13 for performing calibration measurements also in the area of the axis 112 to position. For example, the magnetic sensor 13 along the axis 112 be moved and / or positioned from different spatial directions or with different orientations close to this, to actual measurements with the magnetic sensor 13 to investigate.

This is advantageous for example because the measuring elements 102 of the measuring sensor 13 primarily provide meaningful measurement signals when penetrated vertically by field lines. To all measuring elements 102 Thus, to obtain useful signals and to incorporate them in the calibration, therefore, arranging the magnetic sensor 13 preferred with different orientations.

Should also the strength and not just the direction of the generated magnetic field with the magnetic sensor 13 can be detected (including an amount of the field strength vector at the ball center point) may be provided to obtain desired values, an additional reference sensor. This can be the magnetic field of the calibration standard 110 pre-measured and, for example, analogous to the sensor assembly 1 out 15 assembled but already calibrated. It is understood that with such a reference sensor and the shape or orientation of the magnetic field itself can be determined or at least made plausible.

In 17 is an alternative embodiment for a calibration standard 110 shown. This is designed as a Helmholtz coil and comprises two individual coils 120 which are concentric or congruent and at a predetermined distance along a longitudinal axis L are positioned to each other. In a conventional manner is doing in an area between the coils 120 as well as the longitudinal axis L generates a substantially homogeneous magnetic field. The magnetic sensor 13 is preferably moved again with different orientations in this area for calibration. In 17 is also a stationary mounted reference sensor 124 which measures the strength of the magnetic field (for example, the amount of magnetic field strength) in said region.

Again, it may be provided, the expected alignment or the course of the magnetic field by optical or tactile measurement of the coils 120 to determine. For this purpose, the already (for example, with the calibration standard 110 out 16 or even a non-magnetic calibration ball) calibrated tactile or optical sensor 2 of the sensor assembly 1 the spools 120 for example, to close their position or distance. This in turn can be used, for example, to set the field strength in the region of the longitudinal axis L be determined.

A further, not separately shown variant relates to a calibration standard in the form of a comparison magnet, which generates a homogeneous magnetic field between two opposing magnets and in which the magnetic sensor 13 is insertable.

LIST OF REFERENCE NUMBERS

1

sensor assembly

2

tactile sensor

3

Taststiftschaft

4

probe ball

5

stylus holder

6

mounting cube

7

renewal

8th

coupling element

9

bearing cylinder

10

electronics box

11

plug

12

flexible circuit board

13

Magnetic Sensor / Hall Sensor

14

cavity

15

rotor

16

magnetic sheet

17

pole

18

gap

19

auxiliary magnet

20

wave

21

Adjusting spring

22

groove

23

stator

24

casing

25

stator

26

Stator back

27

copper windings

28

rotor

29

Shorting ring

30

Shorting bars

31

rotor shaft

32

air gap

33 '

partially finished winding

33

complete winding

34

stator

35

winding

36

winding

37

winding

38

stator

39

gap

40

rotor

41

rotor sheet

42

iron

43

copper

44

copper line

45

electric motor

102

measuring element

104

(Magnetic sensor) coordinate system

110

calibration standard

112

level

120

Kitchen sink

124

reference sensor

L

longitudinal axis

201

measuring table

202

pillar

203

pillar

204

crossbeam

205

rotator

206

scale graduation

207

cross slide

208

Pinole

209

probe

210

mounter

211

coordinate measuring machine

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004048095 A1 [0053]

Claims (19)

Sensor assembly (1) for coordinate measurement on a workpiece (15; 34; 40), comprising an optical or a tactile sensor (2) for coordinate measurement on a workpiece, characterized by a magnetic sensor (13) for measuring magnetic properties of the workpiece. Sensor assembly according to Claim 1 wherein the magnetic sensor (13) is arranged fixed in space relative to the optical sensor or tactile sensor (2) on the sensor assembly (1). Sensor assembly according to one of the preceding claims, wherein the magnetic sensor is arranged close to a measuring point of the optical sensor or touch point of the tactile sensor (2). Sensor assembly according to one of the preceding claims, wherein the magnetic sensor (13) comprises a plurality of measuring elements (102) and in particular wherein at least two of the measuring elements (102) are arranged for measuring a magnetic property in the same spatial direction. Sensor assembly according to Claim 4 wherein at least two measuring elements (102) enclose a predetermined reference point (100) of the optical or tactile sensor (2) between them. Sensor assembly according to one of the preceding claims, wherein the tactile sensor (2) has a Taststiftschaft (3) and a probe element (4) and wherein the magnetic sensor (13) is arranged in or on the Taststiftschaft (3), or the magnetic sensor (13) is arranged in or on the probe element (4). Sensor assembly according to one of the preceding claims, wherein the magnetic sensor (13) is a Hall sensor. Sensor assembly according to one of the preceding claims, wherein from the measurement signals of the magnetic sensor (13) a vector of the measured magnetic field strength can be determined. Coordinate measuring device (211), comprising a sensor assembly (1) according to one of Claims 1 - 8th , Arrangement for calibrating a sensor assembly (1) with a sensor assembly (1) according to one of Claims 1 - 8th and a calibration standard (110) configured to generate a magnetic field having defined characteristics. Arrangement according to Claim 10 wherein the calibration standard (110) is further a calibration standard (110) for the optical or tactile sensor (2). A method for measuring magnetic properties of a workpiece (15; 34; 40), wherein in the method a sensor assembly (1) according to one of Claims 1 - 8th and the method comprises the steps of: - measuring magnetic properties of the workpiece (15; 34; 40) with the magnetic sensor (13) of the sensor assembly. Method according to Claim 12 comprising the step of - measuring coordinates of the workpiece (34) with the optical sensor or the tactile sensor (2) of the sensor assembly (1). Method according to one of Claims 12 - 13 wherein the workpiece is an electric motor (45) or a part (15, 23, 38) of an electric motor. Method according to Claim 14 wherein, in the measurement, the part (15) of the electric motor is moved to generate a moving magnetic field. Method according to Claim 14 or 15 wherein, during the measurement, electrical power is applied to the part (38, 35, 36, 37, 38) of the electric motor to generate a magnetic field. Method according to one of Claims 12 - 16 wherein the magnetic sensor detects a transition from ferromagnetic material (42) to non-ferromagnetic material (43) on the workpiece (40). A method for calibrating a sensor assembly (1), wherein the sensor assembly (1) according to one of Claims 1 - 8th is formed and the method comprises the step of: - Measuring magnetic properties of a calibration standard (110) with the magnetic sensor (13) of the sensor assembly (1). The method of claim any one of the preceding claims, further comprising: - Measuring the calibration standard (110) by probing with the optical or tactile sensor (2), based thereon, the sensor (2) calibrated and / or magnetic properties of the calibration standard (110) is closed.

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