Method for operating a measuring device for surface or contour measurement

Abstract

Method for operating a measuring device for surface or contour measurement on a workpiece, wherein the measuring device - a probe arm carrying a probe body for contacting the surface of the workpiece to be measured, - a feed device for moving the probe relative to the workpiece to be measured along a guideway, - a control device designed and programmed to control the measuring device and to output measurement data on the basis of probe output data output by the probe during scanning of the workpiece, - has interchangeable measuring device components, whereby the mounted measuring device components each define a measuring station configuration, and wherein the control device is designed and programmed to correct the probe output data using an associated compensation data set, characterized by that a memory is provided for storing a plurality of compensation data sets, that each compensation data set represents a difference between the actual guideway and an assumed ideal guideway (guideway deviation) in the respective measuring station configuration, that means are provided for automatically recognizing the respective measuring station configuration defined by the mounted measuring device components and for automatically determining the associated compensation data set from the memory, that the means for automatically recognizing the respective measuring station configuration defined by the mounted measuring device components and for automatically determining the associated compensation data set comprise an electronic identification means on each interchangeable measuring device component, which is in data transmission connection with the control device in the mounting position of the respective measuring device component for reading the identification means and that the difference (guideway deviation) is automatically compensated.

Description

[0001] The invention relates to a measuring device for surface or contour measurement on a workpiece.

[0002] Such measuring instruments are well known and are used particularly in production metrology for various measuring tasks.

[0003] The known measuring devices comprise a probe for contacting the surface of the workpiece to be measured, which probe has a probe arm, and a feed device for moving the probe relative to the workpiece to be measured along a guideway. To adapt the measuring device to different measuring tasks, the measuring device comprises interchangeable measuring device components, with the respective mounted measuring device components defining a measuring device configuration.

[0004] During the measurement of a workpiece, the probe outputs probe output data, the evaluation of which can be used to reconstruct the coarse or fine shape of the surface of the workpiece to be measured in order to determine surface characteristics.

[0005] If all assembled measuring device components conform to the specified specifications without manufacturing or other tolerances, the actual guideway would correspond to an assumed ideal guideway. In this case, the probe output data would directly represent the coarse or fine shape of the surface and thus, without further correction, form the measurement data, which can then be used to determine the desired surface parameters.

[0006] In practice, however, component or other tolerances lead to a difference between the actual guideway and an assumed ideal guideway.

[0007] The document US 2005 / 0 111 725 A1 discloses a surface scanning measuring device and a method for forming a compensation table for a scanning probe.

[0008] The invention is based on the object of specifying a measuring device of the type mentioned in the preamble of claim 1 for surface or contour measurement on a workpiece, the measuring accuracy of which is improved.

[0009] This object is achieved by the invention defined in claim 1.

[0010] The measuring device according to the invention has a memory for storing a plurality of compensation data sets, each of which is assigned to at least one measuring device configuration and represents a difference between the actual guide path and the assumed ideal guide path in the respective measuring device configuration. Using the compensation data set assigned to the respective measuring device configuration, it is thus possible to correct the probe output data to account for the actually existing guide deviations and thereby obtain measurement data that represent the coarse or fine shape of the measured surface without measurement errors caused by guide deviations.

[0011] The invention provides means for automatically recognizing the respective measurement configuration defined by the mounted measuring device components and for automatically determining an associated compensation data set.

[0012] The memory can store corresponding compensation data sets for a number of known measuring device configurations, which were previously determined during a factory calibration of the measuring device by measuring a reference workpiece. Once the respective measuring device configuration has been identified, the corresponding compensation data set can be retrieved from the memory, and the corresponding compensation can be applied to a measurement.

[0013] The control device is designed and programmed to output corrected measurement data for correcting the probe output data using a combination data set assigned to the respective measuring device configuration.

[0014] According to the invention, the respective measuring device configuration is thus automatically recognized, so that, using the assigned compensation data set, the probe output data can be corrected to obtain the measurement data by applying the associated compensation.

[0015] Thus, with the measuring device according to the invention, the compensation of guide deviations or other deviations takes place automatically and without intervention by an operator.

[0016] In this way, operating errors are avoided, so that the process reliability of the measuring device according to the invention is increased.

[0017] By avoiding operating errors, the measuring accuracy of the measuring device according to the invention is improved.

[0018] An advantageous development of the invention provides that the control device is designed and programmed for an automatic determination of a compensation data set assigned to the respective measuring device configuration by retrieval from the memory.

[0019] According to the invention, after automatically recognizing the respective measuring device configuration, the control device retrieves the associated compensation data set from the memory.

[0020] Another advantageous development of the invention provides that the control device is designed and programmed to automatically determine a compensation data set associated with the recognized measuring device configuration by performing a compensation data set determination measurement on a reference workpiece, provided that no compensation data set associated with the recognized measuring device configuration is stored in the memory. In this embodiment, a compensation data set is thus always determined by measuring a reference workpiece if no compensation data set stored in the memory is associated with the recognized measuring device configuration.

[0021] However, if no compensation data set is assigned to the recognized measuring device configuration and stored in the memory, the invention also provides the possibility of determining a compensation data set without performing a compensation data set determination measurement. This is the case, for example, and in particular, when the determined measuring device configuration is so similar to a measuring device configuration for which a compensation data set is available in the memory with regard to the prevailing geometric conditions and mass ratios that the compensation data set for the recognized measuring device configuration can be converted based on the known measuring device configuration.

[0022] The invention provides that the means for automatically recognizing the respective measuring station configuration defined by the mounted measuring device components and for automatically determining an associated compensation data set comprise an electronic identification means on each interchangeable measuring device component. This means, in the mounting position of the respective measuring device component, is in data transmission connection with the control device for reading the identification means. In this embodiment, each measuring device component is recognized using the associated electronic identification means, so that after all measuring device components have been recognized, the resulting measuring device configuration can be automatically recognized. The electronic identification means can be configured in a variety of ways.For example, the identification means can be an RFID chip that is read by a reader that is in data transmission connection with the control device or is integrated into it.

[0023] An advantageous development of the aforementioned embodiment provides that each electronic identification means, in the mounting position of the associated measuring device component, is connected to the control device via a data bus system. This further increases the functional reliability of the measuring device according to the invention.

[0024] Another advantageous development of the invention provides that the exchangeable measuring device components at least - the button and / or - the probe arm and / or - the feed device and / or - a measuring column of the measuring device in which the feed device is arranged so as to be adjustable along at least one axis.

[0025] The invention is explained in more detail below using an exemplary embodiment with reference to the attached highly schematic drawing. All features described, illustrated in the drawing, and claimed in the patent claims, taken individually and in any suitable combination with one another, constitute the subject matter of the invention, regardless of their summary in the patent claims and their references, as well as regardless of their description or representation in the drawing.

[0026] It shows: Fig. 1 a schematic perspective view of an embodiment of a measuring device according to the invention, Fig. 2 shows a block diagram to explain the operation of the measuring device according to the invention and Fig. 3 shows a flow chart to further clarify the functionality of the measuring device.

[0027] To explain an embodiment of a measuring device according to the invention, reference is made below to the Fig. 1 to 3 are referred to.

[0028] In Fig. 1 shows an embodiment of a measuring device 2 according to the invention for surface or contour measurement on a workpiece, which has a base body designed as a base plate 4. A measuring column 6 is attached to the base plate 4.

[0029] The measuring device 2 has a probe 8 for probing the surface of a workpiece to be measured. The probe has a probe arm 10 carrying a probe body 12. A feed device 14 is provided for moving the probe 8 relative to the workpiece to be measured along a guideway. By means of the feed device 14, the probe is movable along a linear feed axis in the direction of a double arrow 16 relative to the workpiece to be measured. The feed device 14 is arranged in a housing 18, which is arranged on the measuring column 6 and is height-adjustable in the direction of a vertical axis (z-axis).

[0030] In the illustrated embodiment, the probe 8 is designed as a tactile probe. Depending on the respective measurement task and requirements, however, the measuring device 2 can also have a non-contact probe.

[0031] The measuring device 2 operates according to the stylus method, which is generally known to those skilled in the art and is therefore not explained in detail.

[0032] To adapt the measuring device 2 to different measuring tasks, the measuring device has interchangeable measuring device components, with the respective mounted measuring device components defining a measuring device configuration. In the illustrated embodiment, the interchangeable measuring device components include the measuring column 6, the probe 8, the probe arm 10, and the feed device 14. Depending on the respective requirements, however, only individual measuring device components can be interchangeable, or additional measuring device components can be interchangeable.

[0033] Fig. Figure 2 shows a block diagram to illustrate the functionality of the measuring device 2. The measuring device 2 has a control device 20, which is designed and programmed to control the measuring device 2.

[0034] During the measurement of a workpiece, its surface is scanned using the probe 8. The probe 8 is in data transmission connection with the control device 20 and transmits probe output data to the control device 20 during the measurement.

[0035] In the theoretical case that the measuring device components of the measuring device 2 were not subject to any component tolerances or other tolerances, the actual guide path along which the feed device 14 guides the probe 8 over the workpiece would correspond to an assumed ideal guide path. Since this is not the case in practice due to component tolerances or other tolerances, there is a difference in practice between the actual guide path and an assumed ideal guide path.

[0036] To avoid measurement inaccuracies, it is necessary to compensate for the resulting guide deviations. Compensation is performed in the control device, which is designed and programmed to output measurement data based on the probe output data generated by probe 8 during scanning of the workpiece. Compensation data is used for the correction.

[0037] Since each measuring device configuration generally entails individual guide deviations due to the prevailing geometric conditions and mass ratios, it is generally necessary to assign a separate compensation data set to each measuring device configuration, which represents the difference between the actual guide path and an assumed ideal guide path in the respective measuring device configuration.

[0038] For storing different measuring device configurations and the respective associated compensation data set, a memory 22 is provided with which the control device is in data transmission connection.

[0039] According to the invention, means are provided for automatically recognizing the respective measuring device configuration defined by the mounted measuring device components and for automatically determining an associated compensation data set. In the illustrated embodiment, these means comprise an electronic identification means in the form of an EPROM on each replaceable measuring device component. This means, in the mounting position of the respective measuring device component, is in data transmission connection with the control device for reading the identification means. Data is stored in the respective identification means that uniquely identify the respective measuring device component with regard to its properties.

[0040] In the illustrated embodiment, a data bus system 24 is provided, via which the control device 20 is in data transmission connection with the identification means of the respectively mounted measuring device components (measuring column 6, probe 8, probe arm 10, feed device 14).

[0041] After reading the electronic identification means assigned to the replaceable measuring device components, the respective measuring device configuration can be automatically determined in the control device 20. A compensation data set assigned to the recognized measuring device configuration can be read from the memory 22. Corresponding configuration data sets for a plurality of measuring device configurations can be determined during the factory calibration of the measuring device 2 by measuring a reference workpiece, for example, a flat glass pane, and stored in the memory 22.

[0042] To compensate for guide deviations, the control device 20 is designed and programmed to output corrected measurement data for correcting the probe output data using a compensation data set assigned to the detected measuring device configuration.

[0043] The measuring device 2 according to the invention thus enables the automatic application of compensation data without operator intervention. This reduces the risk of measurement inaccuracies due to inappropriate compensation or correction of the guide deviations after replacing measuring device components, thus significantly increasing the process reliability of the measuring device according to the invention.

[0044] In Fig. 3 shows a flow chart, based on which the functioning of the measuring device 2 according to the invention is further explained below.

[0045] At 100, a program running in the control device 20 starts.

[0046] At 102, the measuring device configuration is determined by reading the electronic identification means assigned to the interchangeable measuring device components—in the illustrated embodiment, the measuring column 6, the probe 8, the probe arm 10, and the feed device 14. The interchangeable measuring device components are each connected to the measuring device 2 and the data bus system 24 via an electromechanical interface.

[0047] After reading out the measuring device configuration, the control device 20 checks by accessing the memory 22 whether the existing measuring device configuration is known (cf. 104 in Fig. 3).

[0048] If the existing measuring device configuration is known (“yes” at 104), the corresponding compensation data set is retrieved from the memory 22 and applied at 106 (cf. 108 in Fig. 3).

[0049] After performing a measurement using the resulting compensation or correction of the probe output data, the compensated or corrected measurement data can then be output (see 110 in Fig. 3), which represent the coarse or fine shape of the surface of the workpiece to be measured, depending on the respective measuring task.

[0050] If the automatically detected measuring device configuration is not known (“no” at 104), the control device 20 uses access to the memory 22 to determine whether a similar measuring device configuration is known and whether an associated compensation data set is stored in the memory for this purpose (cf. 112 in Fig. 3).

[0051] According to the invention, a similar measuring device configuration is understood to mean that the recognized measuring device configuration deviates from a measuring device configuration stored in the memory, in particular with regard to the existing geometric relationships and mass ratios, only to such an extent that, within the scope of the desired measurement accuracy, a compensation data set associated with the known measuring device configuration can be converted that matches the recognized measuring device configuration.

[0052] If a similar measuring device configuration is known and the corresponding compensation data set is stored in the memory 22 (“yes” at 112), the corresponding compensation data set is retrieved (cf. 114 in Fig. 3) and converted (cf. 116 in Fig. 3).

[0053] The configuration data set determined by conversion is then stored in the memory 22 (see 118 in Fig. 3).

[0054] The compensation data set thus determined can then be applied, the measurement carried out and the associated measurement data output (see 108 and 110 in Fig. 3).

[0055] If a measuring device configuration similar to the automatically recognized measuring device configuration in the sense of the invention is not known (“no” at 112), an associated compensation data set can be determined by measuring a reference workpiece (cf. 120 and 122 in Fig. 3).

[0056] The compensation data set determined by measurement can then be saved (see 118 in Fig. 3). The measurement can then be carried out, the compensation applied and the measurement data output (see 108 and 110 in Fig. 3).

Claims

[1] Method for operating a measuring device for surface or contour measurement on a workpiece, wherein the measuring device - a probe arm carrying a probe body for contacting the surface of the workpiece to be measured, - a feed device for moving the probe relative to the workpiece to be measured along a guideway, - a control device designed and programmed to control the measuring device and to output measurement data on the basis of probe output data output by the probe during scanning of the workpiece, - has interchangeable measuring device components, whereby the mounted measuring device components each define a measuring station configuration, and wherein the control device is designed and programmed to correct the probe output data using an associated compensation data set, characterized by , that a memory is provided for storing a plurality of compensation data sets, that each compensation data set represents a difference between the actual guideway and an assumed ideal guideway (guideway deviation) in the respective measuring station configuration, that means are provided for automatically recognizing the respective measuring station configuration defined by the mounted measuring device components and for automatically determining the associated compensation data set from the memory, that the means for automatically recognizing the respective measuring station configuration defined by the mounted measuring device components and for automatically determining the associated compensation data set comprise an electronic identification means on each interchangeable measuring device component, which is in data transmission connection with the control device in the mounting position of the respective measuring device component for reading the identification means and that the difference (guideway deviation) is automatically compensated. [2] Method according to claim 1, characterized by that the control device is designed and programmed for automatic determination of a compensation data set belonging to the respective measuring station configuration by retrieval from the memory. [3] Method according to claim 1 or 2, characterized bythat the control device is designed and programmed for an automatic determination of a compensation data set belonging to the respective measuring station configuration by carrying out a compensation data determination measurement on a reference workpiece, provided that no compensation data set assigned to the respective measuring station configuration is stored in the memory. [4] Method according to one of the preceding claims, characterized by that each electronic identification means is in data transmission connection with the control device via a data bus system. [5] Method according to one of the preceding claims, characterized by that the replaceable measuring device components are at least - the probe arm and / or - the feed device and / or, - the button and / or, - a measuring column of the measuring device on which the feed device is arranged so as to be adjustable along at least one axis.

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