DE19821371A1 - Measuring workpiece with coordinate measuring appliance - Google Patents

Abstract

The method is carried out in steps, so that at least one test parameter to be evaluated in the control operation is established. At least one geometric element to be scanned at the workpiece is assigned to the test parameter established, defining the method course for the scanner (11), for scanning the at least one geometric element. The workpiece (12) is then scanned by the scanner, according to the method course. The test parameter to be tested is evaluated based on the measurement data resulting from the measuring operation.

Description

The invention is based on a method for measuring a Workpiece with a coordinate measuring machine by a automated measurement process and a corresponding Coordinate measuring device.

Such methods have long been known from the prior art and usually have the following steps:

• - Creation of the measurement process, in particular by Traverse paths for the button of the coordinate measuring machine as well the test characteristics to which the in Measured values obtained from the measurement sequence can be evaluated.
• - Execution of the measuring sequence in which the button of the Coordinate measuring device the workpiece to be measured scans and measurement data are recorded.
• - Evaluation of the test characteristics to be tested on the basis of the Measurement data recorded.

With regard to the creation of the measurement process has so far been known methods compiled a list of parameters, in the sequentially a lot of individual information had to be entered. For example, probing, Detour routes, calculation rules, links from Measuring elements, evaluations, target values, tolerances etc. can be entered. The input had to be the actual one Measurement sequence can be entered as follows, d. i.e. before a Inspection characteristic, such as the shape deviation of a Geometric element of the predetermined target shape or a Check the position of the center of a hole first, the geometry or geometries in question had to be elements in the list. Only when that Geometry element was defined, the program could base on this data, an entry of the corresponding test characteristics accept.  

This led to long and confusing parameter lists. In particular, changes to the parameter lists required a lot of effort and confusion often to unforeseen results, for example Parameters have been deleted from a parameter list to which the following parameters of the list are referenced.

The object of the present invention is therefore a Process of the type mentioned above and a corresponding To propose coordinate measuring machine with which the measuring sequence can be generated and changed more easily.

The object is achieved according to the features of the independent claims 1 and 7 solved.

The special feature of the method according to the invention is here to see that first a test characteristic to be checked is specified and the specified test characteristic in one the next step in the process to calculate the Test feature on the geometric elements to be scanned on the workpiece be assigned.

By entering the data according to the invention, it is possible for creates a significantly higher level of clarity for the operator because this is the first step when creating the travel paths of the parameters that interest him, namely the Inspection characteristics, and can be based on all of them can make logical assignments. The programming is done with this approach on schedule.

The clarity is also significantly increased if the test features to be tested in the measurement process together in one List are summarized. This allows the operator of the Coordinate measuring device easily overview which test features be recorded in a measurement sequence without being uninteresting Details of being distracted.  

The list is particularly advantageously designed so that the Inspection characteristics are arranged in the order in the list, how they are evaluated one after the other in the measuring sequence. Hereby the operator of the coordinate measuring machine can also use the Overview of the chronological order of the measuring sequence.

The assignment of the detailed parameters, such as in particular geometric elements to be scanned for an inspection characteristic particularly advantageous here, via pointer. This has the special advantage that the design of the list very much can be easily changed. For example, this can the order of the test characteristics can be changed simply by any test feature together with the corresponding Pointers from the list being chained and to another Place is chained back into the list.

Deleting an inspection characteristic can also be carried out without any problems go because when deleting the inspection characteristic only that relevant test characteristic from the list and chained together is deleted with the corresponding pointers. All other Elements with which the inspection characteristic was originally based on the Pointers were chained, remain after deleting the corresponding test characteristic unchanged, so that thereby the unintentional deletion of technology necessary elements to which others may be Access inspection characteristics, can be prevented.

Further advantages and developments of the method can be found in the exemplary embodiment shown in FIGS. 1 to 6.

Show here:

Figure 1 is an exemplary representation of a coordinate measuring device.

Fig. 2 is a flowchart of an inventive method;

Fig. 3 is an exemplary illustration of one (12) on which an inspection, where the symmetry deviation (t) is to be determined workpiece;

According to which a workpiece can be measured 4 is a purely schematic illustration of a protocol.

Fig. 5 is a purely schematic representation of a test feature list ( 32 ), the individual test features are linked via pointers with corresponding subordinate elements of a further measuring element list ( 33 ); and

Fig. 6 is a purely schematic representation of the data or object structure of a test plan.

Fig. 1 shows, schematically and purely by way of example a coordinate, with which the inventive method can be performed. The coordinate measuring machine has a measuring table ( 1 ) on which the portal ( 2 ) of a portal mechanism ( 10 ) is movably guided in the direction of the arrow (Y). The gantry ( 2 ) is moved in the said direction by a drive (not shown in more detail), for example a friction wheel drive or a spindle drive, the exact position being scanned on the scale ( 9 ). In an analogous manner, a cross slide ( 3 ) is movably guided in the direction of arrow (X) on the crossbeam of the portal ( 2 ), which is also driven by a drive and whose exact position is scanned on the scale ( 7 ). In addition, the sleeve ( 4 ) is movably guided on the cross slide ( 3 ) in the third direction (Z), the movement also being realized by a corresponding drive and the exact position of the sleeve ( 4 ) on the scale ( 8 ) is scanned. At the lower end of the sleeve ( 4 ) there is a button ( 11 ) comprising a measuring probe ( 5 ) and a stylus ( 6 ) which is attached to the probe ( 5 ). The measuring probe ( 5 ) can measure the deflection of the stylus ( 6 ) relative to the probe ( 5 ) by means of corresponding sensors, not shown here.

Through the portal mechanism ( 10 ), the button ( 11 ) and thus the stylus ( 6 ) of the button ( 11 ) can be moved accordingly in all three mutually perpendicular coordinate directions (X, Y, Z) via the portal mechanism ( 10 ) just described. The button ( 11 ) or the drives of the portal mechanism ( 10 ) to which the button ( 11 ) is attached is moved by a control unit ( 15 , 16 ) described in more detail below in such a way that the workpiece ( 12 ) is touched by the stylus ( 6 ), the stylus deflection of the stylus ( 6 ) relative to the probe ( 5 ) and the machine positions scanned on the scales ( 7 , 8 , 9 ) being taken over in the respective probing positions and corresponding measurement data being derived therefrom can.

The measuring sequence is carried out by a control unit ( 15 , 16 ). A controller ( 15 ) is provided in the control unit ( 15 , 16 ) for controlling the drives of the portal mechanics ( 10 ) and for recording the machine positions scanned on the scales ( 7 , 8 , 9 ) and for the stylus deflection of the stylus ( 6 ). The controller ( 15 ) is connected to a computer ( 16 ) via a corresponding interface. The computer ( 16 ) is used essentially to determine the measurement sequence and to evaluate the measurement data recorded during the measurement.

Of course, the coordinate measuring machine described here is only described as an example. For example, the mechanics for moving the probe ( 5 ) can also have a different structure, such as, for. B. act a stand mechanism in which a horizontally movably guided stand is provided on a measuring table. A cross slide is in turn mounted vertically displaceably on the stand. On the cross slide, in turn, a measuring arm is mounted horizontally displaceable, at the end of which the button is located.

The button can of course also vary in many ways. So can for example, instead of a measuring probe so-called switching probe can be used, in which a touch of the workpiece with the stylus only one Signal is emitted. But it can also be, for example Optical buttons can be used on the workpiece surface optically scanned.

The method according to the invention for measuring a workpiece will now be described on the basis of a greatly simplified flow chart according to FIG. 2.

First of all, a test feature is defined in the computer ( 16 ), which is to be evaluated in the subsequent measurement sequence on the basis of the measurement data recorded in the measurement sequence. This can be a wide variety of test features, such as the positional deviation of a geometric element from that of a predefined target position, the shape deviation of a geometric element from the target shape, the symmetry deviation of several geometric elements from one another, the roughness, etc. The relevant test characteristic is, like this will be described in more detail below, added to a corresponding list of test features.

In a next step, starting from the defined test characteristic, all the detailed parameters necessary for determining the test characteristic are assigned. The assignment also takes place on the computer ( 16 ) by opening further detailed forms on the screen of the computer ( 16 ) based on the defined test feature, in which the corresponding parameters can be defined. An essential detail parameter, which is ultimately at the end of each assignment chain, is, in particular, the geometric element or elements to be measured on the workpiece to be measured. Geometric elements are to be understood here as all basic elements by means of which the touching of the probe ( 11 ) on the workpiece ( 12 ) is defined. The list of geometry elements usually consists of the point, the straight line, the curve, the free-form surface, the plane, the torus, the cone, the paraboloid, the sphere, the cylinder, the ellipse, the circle, the slot, the groove and the rectangle. On the basis of these geometric elements, the points on the workpiece surface to be scanned by the probe ( 11 ) are then further defined in a third step ( 19 ). The travel paths can either be generated manually by programming the intermediate positions and the points to be scanned with the associated normal vectors, or automatically.

With manual programming, the individual intermediate positions and the points to be scanned with the normal to the Normal vector pointing workpiece surface manually in one so-called "Teach In" entered.

The automatic generation will be for the individual Geometry elements first use macros to move the Sampling the geometric elements generated, as well as in a next one Step over corresponding further macros between the Geometry elements that generate the travel paths. A detailed Description of this is, for example, our US patent No. 5,491,638, to which reference is hereby expressly made is taken.

After the travel paths have been defined, in a next step ( 20 ) the computer ( 16 ) transfers data to the control ( 15 ), on the basis of which the control moves the mechanics of the coordinate measuring machine accordingly and during the process of the scales ( 7 , 8 , 9 ) and the button ( 11 ) records the signals and passes them on to the computer ( 16 ). The operation of such a controller ( 15 ) is described purely by way of example in our US Pat. No. 5,471,406, to which we hereby expressly refer.

On the basis of the transferred measurement data, the test features listed in the list are then evaluated in a final step ( 21 ) in the computer ( 16 ) in accordance with the specifications.

How the creation of a measurement sequence in the computer ( 16 ) takes place will now be explained with reference to a specific measurement example in connection with FIGS . 3 and 4.

For this purpose, it should first be mentioned that the computer ( 16 ) is a standard PC which is equipped with at least one screen, a CPU, a hard disk, a working memory, a keyboard and an interface card. The computer ( 16 ) communicates with the controller ( 15 ) via the interface card. The structure of such a computer and the mode of operation are already so well known to the person skilled in the art that a drawing of the individual components of the computer, which would be without information content, is dispensed with here. If in the text below individual functions that take place in the computer ( 16 ) are explained, it should be explicitly clarified once again that the functions are implemented by programs that are initially on the hard disk and are loaded into the main memory during runtime by where you then control the components of the computer ( 16 ). The data that are recorded or processed during the execution of the program, e.g. B. the parameters of the geometric elements to be measured are also initially in the working memory during use of the coordinate measuring machine and are saved in corresponding files on the hard disk at the latest before the computer ( 16 ) is switched off.

As can be seen from FIG. 3, the workpiece ( 12 ) to be measured is a plate with two bores (b1, b2). As a test feature, the symmetry offset (t) between the bores (b1, b2) and the lateral planes (e1, e2) should be determined for the workpiece ( 12 ) in question.

The problem will be solved by measuring first the bores (b1, b2) along a circle (k1, k2) are measured, from this the center of the circle (mk1, mk2) can be determined and from this the point of symmetry (sp) between  the two center points (mk1, mk2) is calculated. Furthermore the levels (e1, e2) will be measured and from here between the said levels (e1, e2) Determine the plane of symmetry. The symmetry deviation (t) then results from the shortest distance from the point of symmetry (sp) to the plane of symmetry (se).

The measurement sequence is entered by creating a so-called test plan, as will now be explained purely schematically with reference to FIG. 4. According to the invention, the test feature, that is to say in this example case the symmetry deviation (t), is first defined and an appropriate test feature list ( 32 ) is added. In a next step, more detailed parameters are specified in a further form ( 27 ) and ( 30 ) using a corresponding form for the test characteristic, such as in list ( 27 ) the specified target value for the symmetry deviation (t), the maximum permissible tolerance and in the list ( 30 ) also a field in which the actual actual value is stored. Based on this, another form ( 28 ) is used to define linking elements, namely the symmetry point (sp), which is to be derived from the measured circle centers (mk1, mk2) and the plane of symmetry (se) in the later measurement sequence later measurement sequence is to be derived from the measured levels (e1, e2). In addition, fields for the actual measurement results of the linking elements (sp, se) are additionally created in the list ( 31 ). Starting from these linking elements, so-called measuring elements are now generated via another detailed form, which are stored in a list ( 33 ) for measuring elements. These measuring elements collect all the information that is ultimately necessary to measure a geometric element. In order to provide this information accordingly, detailed parameters are again generated in corresponding subforms on the basis of the measuring elements in other lists, as shown in FIG. 3 only as an example for the measuring element "circle k2".

In this case, detailed parameters for the button to be used and the resources to be used were stored in a list ( 34 ) for the measuring element "circle k2". In addition, an entry is provided in a list ( 29 ) for the measurement data currently measured in a measurement sequence for the measurement element in question. An entry is created in a list ( 34 ) in which technological data relating to the specific measuring technology is stored. This can be, for example, data about the travel paths or the generation of the travel paths.

As an essential entry, in particular in a list ( 26 ) the geometric element actually to be measured on the workpiece ( 12 ), namely here the circle (k2), is defined.

As already explained above, the test features to be determined one after the other in the measurement sequence are compiled in the list ( 32 ) in their order in which they are processed in the measurement sequence, as is shown purely schematically in FIG. 5. As can be seen from FIG. 5, six test features are listed one after the other in the list ( 32 ) in accordance with the sequence of the measurement sequence, each of the test features being shown purely schematically by pointers in the form of arrows with corresponding elements from other lists . The list of measuring elements ( 33 ) was shown here as a representative of all possible lists. The measurement process can be changed very easily with this structure. For example, the list element "test characteristic 3" can be linked from the list ( 32 ) together with its pointer to the list ( 33 ) and linked between the list entries with the names "test characteristic 1" and "test characteristic 2". Since the pointer to the "measuring element 5" of the list ( 33 ) has remained unchanged, only the sequence of the test features to be processed in succession has changed, while the assignments of the "test feature 3" to the corresponding "measuring element 5" in the list ( 33 ) has of course remained unchanged.

Of course, test features can also be simply deleted from the list, as was shown purely schematically in FIG. 5 using the list entry "test feature 6". The test feature can be deleted here by chaining it out of the list ( 32 ) and deleted together with the corresponding pointer to the list element "measuring element 4". Due to the deletion process, however, the corresponding list element "measuring element 4" in the list ( 33 ) remains completely unchanged, so that the corresponding measuring element for evaluation by, for example, other test features still remains.

A complete data system or object system of lists for a complete test plan, with which the measurement sequence can be defined, will now be described by way of example with reference to FIG. 6. At this point it should be noted that this is a greatly simplified sketch of such a test plan. The test plan is actually programmed object-oriented, so that the lists are actually separate objects. Thus, the lists include not only data that are changed by a corresponding higher-level program, but also functional methods by means of which the lists manage themselves in terms of programming.

As can be seen from FIG. 6, the test plan ( 38 ) is structured into three basic subsets, namely a section ( 37 ) with the designation "target workpiece", in which the information relating to the target workpiece to be measured is stored, a section ( 35 ) with the designation "measurement" in which all lists relevant for the measurement are arranged and a third section ( 36 ) with the designation "actual workpiece" in which all data for the actually measured workpiece are stored.

Section workpiece ( 37 ):
The section ( 37 ) in which the target workpiece data are stored here contains a list ( 26 ) with the designation "geometry", in which the geometric elements of the workpiece to be measured are present. These geometric elements are either loaded into the relevant list by a CAD system and subsequently assigned to the test characteristics, as shown above, or are only defined by the operator of the coordinate measuring machine during the creation of the test plan. In the list ( 28 ) labeled "Link", elements are entered that result from the linking of several measured geometric elements. For example, as described in the measurement example above, this can be a point of symmetry that is calculated from the center points of two measured circles. In the list ( 27 ) with the inscription "test feature", the detailed information relating to the test features to be measured on the workpiece, which were created in the list ( 32 ), is finally stored. Such detailed features can be, for example, the target value or the tolerance and the result of an evaluation of the relevant test feature.

Measurement section ( 35 ):
The second section ( 35 ) labeled "Measurement" comprises two lists. First of all, reference is made to the list ( 32 ) "sorted test features", which is the central focus of the invention. In the list ( 32 ), the test features are stored as they are processed one after the other in the measuring sequence. In this list, only the type of the test characteristic and its chronological sequence in the measurement process are defined. From this list ( 31 ) all entries in the other lists are subordinated.

In the list (32/33) with the label sensing element / Meßtechnologie the sensing elements to be measured are stored together with the sampled points thereon, and the traverse paths between the geometry elements.

Section actual workpiece ( 36 ):
In the third section ( 36 ) with the designation "ACTUAL workpiece", all information about the workpiece measured after the execution of a measuring sequence is stored. The Geometry list ( 29 ) contains the actual data of the geometry elements measured on the actual workpiece, which data was predefined in the list ( 26 ) "Target elements" beforehand. The list ( 30 ) with the designation "linkage" contains the linkage elements evaluated on the basis of the measurement and predefined in the list ( 28 ). The list ( 45 ) with the designation "test characteristic" contains the measurement results desired by the operator in the list ( 32 or 27 ) predefined test characteristics.

Claims (11)

1. Method for measuring a workpiece with a coordinate measuring machine by means of an automated measuring sequence comprising the following method steps:

• - Definition of the automatic measuring sequence, comprising the following process steps:
  • - Specifying at least one test feature to be evaluated on the basis of the measurement data recorded in the measurement process;
  • - Assigning at least one geometric element to be scanned on the workpiece to the defined test feature (t) and defining the travel path for the probe ( 11 ) for scanning the at least one geometric element (k1, k2, e1, e2);
• - Scanning the workpiece ( 12 ) according to the travel path with the button
• - Evaluation of the test feature to be checked on the basis of the measurement data recorded in the measurement process.

2. The method according to claim 1, wherein the test features to be tested in the measurement sequence are combined in a list ( 34 ). 3. The method according to claim 2, wherein the test features in the Order are stored in the list as they are in Measurement sequence can be evaluated one after the other. 4. The method according to claim 1, wherein the assignment of at least one geometric element to said Inspection feature is carried out via a link element (sp, se). 5. The method of claim 1, wherein the assignment of Geometric element takes place via at least one pointer. 6. The method according to claims 2, 3 or 5, wherein the The order of the list can be changed as required.   7. Coordinate measuring machine with

• - A button ( 11 ) which is movably mounted on a mechanism ( 10 ) in the three coordinate directions (X, Y, Z)
• a control unit ( 15 , 16 ) for controlling the mechanics and for recording the measurement data determined during an automated measurement sequence and for defining and evaluating a measurement sequence,
  characterized in that
• - In the control unit for defining the measuring sequence, at least one test feature (t) to be evaluated on the basis of the measuring data recorded in the measuring sequence can be determined
• - That in the control unit, at least one geometry element (k1, k2, e1, e2) to be scanned on the workpiece can then be assigned to the specified test feature and the travel path for the button ( 11 ) for scanning the at least one geometry element (k1, k2, e1, e2) can be determined.

8. coordinate measuring machine according to claim 7, wherein the Test characteristics in a list in a memory of the Control unit are stored. 9. Coordinate measuring device according to claim 8, wherein the Test characteristics are saved in the order in the list are how they are evaluated one after the other in the measuring sequence become. 10. Coordinate measuring device according to claim 7, wherein the assignment of the geometric element to an inspection characteristic at least one pointer occurs. 11. Coordinate measuring device according to claims 8, 9 or 10, wherein the list is stored such that the order of the List can be changed as required.