Measuring body for inspecting geometric deviation of three-axis machine tool, three-axis machine tool, and method for correcting geometric deviation of three-axis machine tool

Abstract

The present invention relates to a measuring body for geometric deviation inspection in a three-axis machine tool (1). The measuring body (2) includes a base plate (8), a first wall portion (10) disposed on the base plate (8) and protruding vertically from the base plate (8), and a second wall portion (20) disposed on the base plate (8), protruding vertically from the base plate (8), and disposed orthogonally to the first wall portion (10). A first opening row (101) and a second opening row (102) are formed in the base plate (8). The first wall portion (10) is a stepped triangle and includes a stepped region (12) having a plurality of stepped portions (13) in an upper exposed region (11). The second wall portion (20) is a square wall portion and includes a first wall portion opening row (22) in an upper exposed region (21) extending parallel to the base plate (8). The first opening row (101) is arranged parallel to the stepped portion opening row (14), and the second opening row (102) is arranged parallel to the first wall portion opening row (22).

Description

[Technical Field]

[0001] The present invention relates to a measuring body for inspecting geometric deviations of a three-axis machine tool, a three-axis machine tool with improved geometric accuracy, and a method for inspecting and correcting geometric deviations of a three-axis machine tool. [Background technology]

[0002] A known area of ​​concern for machine tools is the geometric accuracy of the machine tool. The geometric accuracy of a machine tool is measured by the deviation of the machine's actual position and orientation relative to a target position and orientation with respect to the workpiece. This error causes deviations from the ideal workpiece geometry, which in turn reduces the operating accuracy of the machine tool. To improve geometric accuracy, the deviations of the individual axes and their relative positions and orientations with respect to each other are typically considered.

[0003] Assuming a rigid body model, the three-axis machine tool in this case has three types of linear deviations (one axial and two perpendicular to the axial directions) and three types of rotational deviations (yaw, pitch, and roll). Therefore, there are six types of deviations for each linear axis, or 18 types of deviations for the three linear axes. Furthermore, three types of perpendicularity deviations of the linear axes relative to each other must also be considered. Thus, a three-axis machine tool can have a total of 21 types of geometric errors. In this case, the individual deviations can compound to produce a significant overall error, which can have an undesirable impact on the geometric accuracy of the machine tool. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a measuring body and a three-axis machine tool for inspecting geometric deviations of a three-axis machine tool that are constructed as simply and cost-effectively as possible, and a method for inspecting and correcting geometric deviations of a three-axis machine tool that can be implemented as cost-effectively and quickly as possible. [Means for solving the problem]

[0005] This object is achieved by a measuring body having the features of claim 1, a three-axis machine tool having the features of claim 10, and a method having the features of claim 12. The dependent claims in each case indicate further preferred developments of the invention.

[0006] In contrast, the measuring body for checking geometric deviations of a three-axis machine tool according to the present invention, having the features of claim 1, has the advantage that with the aid of the measuring body, the geometric deviations of the three-axis machine tool can be corrected so that the three-axis machine tool does not have any linear, rotational, or squareness deviations. This allows the three-axis machine tool to machine workpieces with the highest possible level of precision. In this case, correction data determined on the basis of the measuring body can be directly used for error correction of the three-axis machine tool. The measuring body is particularly suitable for machine tools used in ultra-high-precision machining. The measuring body is also particularly suitable for inspecting, correcting, and long-term evaluating machine tools, thereby enabling the machine tool to be used for ultra-precision machining throughout its entire service life.

[0007] This is achieved by the present invention in that the measuring body comprises a base plate, a first wall, and a second wall. The first wall is arranged on the base plate, which is particularly square, and protrudes perpendicularly from the base plate. The first wall is a stepped triangular shape, and has a stepped region with multiple steps in its upper exposed area. Furthermore, the second wall is a square, and is arranged to protrude perpendicularly from the base plate and is arranged perpendicular to the first wall. Furthermore, a first row of openings and a second row of openings are formed in the base plate. Thus, the first wall is configured in a stepped shape with multiple steps on opposite sides away from the base plate. The second wall is a square wall, particularly a rectangular wall, and has an upper exposed area parallel to the base plate, and the first wall opening row is formed in this exposed area.

[0008] Thus, the stepped region of the first wall portion is present in the upper exposed region of the first wall portion. The upper exposed region of the first wall portion therefore forms a step that allows different positions in the Z direction to be detected, and the base plate extends to a base plane in the X and Y directions. Due to the stepped upper exposed region of the first wall portion, the first wall portion has a substantially triangular shape.

[0009] It is particularly preferred that the stepped first wall portion has a row of step openings, with one opening formed in each step, which allows detection of positions in the X and Y directions at different heights in addition to measuring the position in the Z direction.

[0010] It is further preferred that the measuring body has a third wall portion disposed on the base plate and positioned perpendicular to the second wall portion. The third wall portion, like the second wall portion, is a rectangular wall having an upper exposed area extending parallel to the base plate and is provided with a second wall portion opening row. Therefore, the third wall portion is disposed on the base plate parallel to the first wall portion. Therefore, the first wall portion opening row and the second wall portion opening row are disposed perpendicular to each other. In this case, a U-shaped arrangement is formed by the first wall portion, the second wall portion, and the third wall portion.

[0011] It is further preferable that the measuring body has a third row of openings on the base plate that is parallel to the second wall opening row of the third wall.

[0012] The first, second, and third opening rows preferably extend above the base plate so as to be parallel to one end of the base plate, which is preferably rectangular. Thus, the first opening row is preferably parallel to the first end of the base plate, the second opening row is preferably parallel to the second end of the base plate, and the third opening row is preferably parallel to the third end of the base plate.

[0013] It is particularly preferable that the first opening row is parallel to the first wall portion, and / or the second opening row is parallel to the second wall portion, and / or the third opening row is parallel to the third wall portion, thereby enabling the measurement body to detect yaw direction errors, pitch direction errors, and roll direction errors.

[0014] The first row of apertures, the second row of apertures and the third row of apertures particularly preferably have the same number of apertures, the same spacing between apertures and the same aperture diameter.

[0015] According to a further preferred embodiment of the present invention, the first wall, the second wall and the third wall are spaced apart from the first end, the second end and the third end, respectively.

[0016] It is further preferred that the step surfaces of the triangular stepped steps are parallel to the base plate and are polished or otherwise precisely machined to achieve excellent flatness. It is also preferred that the upper exposed regions of the second wall and / or third wall are polished or otherwise precisely machined to achieve excellent flatness. As a result, the accuracy of measurements using the measuring body can be significantly improved.

[0017] It is further preferred that the region of the base plate where the first opening row and / or the second opening row and / or the third opening row are formed and / or the region adjacent to these opening rows is provided as a polishing region.

[0018] It is further preferred that the measuring body has a reinforcing element on the underside of the base plate to improve the stability of the measuring body. The reinforcing element is preferably a slat cross including two slats, each slat connecting two opposite corners of the base plate on the underside of the base plate. The reinforcing element is preferably also used to clamp the measuring body in the machine tool.

[0019] More preferably, the first, second and third aperture rows are arranged on the base plate such that, in the case of a square base plate, one aperture for the measurement process is formed in each corner region of the base plate.

[0020] The base plate is preferably rectangular, particularly square. More preferably, each of the opening rows, the step opening rows, and the first and second wall opening rows of the base plate includes at least one reference opening. The peripheral area of ​​each reference opening is preferably polished, so that the polished surface can be used as a reference element for determining the Z coordinate. The center of each reference opening can be used as a reference element for the X and Y coordinates.

[0021] More preferably, the openings in the first opening row, the second opening row and the third opening row are arranged in a straight line.

[0022] The measuring body is preferably made of Invar, which has a very low coefficient of thermal expansion and is particularly well suited for manufacturing the measuring body. More preferably, the thickness of the first, second and third walls is the same as the thickness of the base plate.

[0023] The present invention further relates to a three-axis machine tool comprising a tool spindle, a measuring device, particularly a 3D measuring sensor, that can be clamped to the tool spindle, and a control unit for controlling the three-axis machine tool. The three-axis machine tool also comprises a measuring body according to the present invention, and the control unit is configured to correct the geometric data of the three-axis machine tool based on a target / actual comparison between predetermined geometric target dimensions of the measuring body and actual geometric dimensions of the measuring body measured by the measuring device on the three-axis machine tool. Therefore, the control unit has a memory for storing the geometric target dimensions of the measuring body determined by the measuring device in a previous step. When measuring the actual geometric dimensions of the measuring body on the three-axis machine tool, the control unit preferably starts an NC program for measuring the measuring body to measure the actual values ​​of the measuring body. In this way, the geometric data of the three-axis machine tool is corrected by comparing the target values ​​with the actual values, and as a result of this correction, the accuracy during machining of the workpiece using the three-axis machine tool is significantly improved. Therefore, correction of geometric errors on the three-axis machine tool can be achieved in a simple manner. The target values ​​are preferably stored in the memory.

[0024] Furthermore, the present invention relates to a method for checking and correcting geometric deviations in a three-axis machine tool, said method comprising: - clamping a measuring device, in particular a 3D measuring sensor, to a spindle of a three-axis machine tool; - placing the measuring body according to the invention in the working space of a three-axis machine tool, in particular by clamping the stiffening elements; - approaching the measuring device to different positions on the measuring body in order to obtain geometrical actual data on the measuring body; - a target / actual comparison between the acquired actual data of the measuring body and predetermined target data in order to measure geometric deviations, in particular linear deviations, rotational deviations and squareness deviations; - a step of correcting the geometric deviation of the three-axis machine tool in a control unit of the three-axis machine tool to improve the machining accuracy of the three-axis machine tool; Includes.

[0025] In this case, the method according to the invention can be carried out relatively quickly and reliably, and in particular can be carried out at the customer's site within a short time after delivery of the three-axis machine tool, so that the conditions at the customer's site, in particular the temperature conditions, do not adversely affect the geometric accuracy of the three-axis machine tool during operation.

[0026] Of course, the method can also be carried out in the manufacturing site of the three-axis machine tool in order to optimize the production process in the manufacture of the three-axis machine tool as much as possible.

[0027] Preferably, the target values ​​of the measuring body are predetermined in the coordinate measuring machine, and then the measuring body is placed in the workspace of the three-axis machine tool so that the coordinate system of the measuring body corresponds to the coordinate system of the three-axis machine tool.

[0028] It is more preferable to detect the temperature of the work space when measuring the measurement object on the three-axis machine tool, and correct the actual data based on the detected temperature of the work space, thereby further improving the accuracy of geometric deviation correction.

[0029] The method according to the invention is preferably useful for the inspection, correction and long-term evaluation of three-axis machine tools, in which case the method according to the invention preferably comprises: - Position deviation in each case (parallel displacement of each axis (three possible errors due to three axes)) - two straightness deviations for each axis (parallel displacements transverse to the axial direction), i.e. six possible geometric errors in total, and - Three types of rotational deviations in each of the three axes, namely, deviations in the yaw, pitch, and roll directions (i.e., nine types of geometric deviations); - Three types of squareness deviations of the linear axes X, Y, and Z relative to each other (XY squareness deviation, XZ squareness deviation, YZ squareness deviation) It measures 21 possible geometric errors:

[0030] It should be noted that depending on the design and kinematics of the three-axis machine tool, individual errors may be negligible. Preferably, the pitch error of the Y axis is corrected by the positioning error in the Y direction, the straightness error of the Y axis relative to the X direction, and the squareness error between the Y and X axes. In this case, a prerequisite is that the distance from the table to the spindle of the machine tool in the X direction is constant. More preferably, the roll error of the Z axis is ignored, since the tool rotates on this axis. Even more preferably, if the tool length is constant, the pitch error of the Z axis and the yaw error of the Z axis can be ignored. Both of these errors can be corrected by the straightness error and squareness error in the Z axis. In this way, the measurement complexity is reduced. [Brief explanation of the drawings]

[0031] Preferred embodiments of the present invention will now be described with reference to the following drawings. [Figure 1] 1 is a schematic perspective view of a measurement body in a three-axis machine tool according to a preferred embodiment of the present invention. FIG. [Figure 2] 2 is a schematic perspective view of the measuring body of FIG. 1 from a different angle. [Figure 3] FIG. 3 is a schematic plan view of the measuring body of FIG. 2. [Figure 4]FIG. 1 is a schematic side view of a measuring body, showing measurement of pitch direction error of the X axis as an example. [Figure 5] FIG. 1 is a partial side view of a measuring body, showing measurement of an error in the roll direction of the X axis as an example. [Figure 6] FIG. 10 is a schematic diagram showing measurement of the yaw error of the X axis. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, the three-axis machine tool 1 and the measuring body 2 for inspecting the geometric deviation of the three-axis machine tool will be described in detail with reference to FIGS.

[0033] Furthermore, a method for inspecting and correcting geometric deviations of a three-axis machine tool will be described with reference to FIGS.

[0034] As can be seen from FIGS. 1 to 5, the three-axis machine tool 1 has a workspace 3, a spindle 4, and a control unit 9.

[0035] As can be seen from FIG. 1, a measuring body 2 is placed on a machine table 6 of a three-axis machine tool 1 .

[0036] 1 to 3 show the details of the measuring body 2. The measuring body 2 is configured to inspect the geometric deviation of a three-axis machine tool, and by clamping the measuring body once, it is possible to measure a total of 21 types of errors, including all linear errors, rotation errors, and squareness errors. In particular, the measuring body 2 can very accurately determine the coordinates for positioning the tool of the three-axis machine tool 1.

[0037] The measuring body 2 has a flat base plate 8 whose base surface extends in the X and Y directions. The measuring body 2 further has a first wall portion 10, a second wall portion 20, and a third wall portion 30. The first wall portion 10, the second wall portion 20, and the third wall portion 30 are arranged on the base plate 8 and protrude perpendicularly from the base plate 8 to form a U-shape.

[0038] As shown in FIG. 2, the Z direction is perpendicular to the X direction and perpendicular to the Y direction.

[0039] As can be seen from FIG. 2, in this case, the first wall portion 10, the second wall portion 20 and the third wall portion 30 are arranged on the base surface of the base plate 8.

[0040] The base plate 8 is configured in a square shape and has a first end 81, a second end 82, a third end 83 and a fourth end 84.

[0041] As can be seen particularly in Figures 1 and 2, the three walls 10, 20, 30 are configured to have different geometrical shapes. In this case, the first wall 10 is a stepped triangle with an upper exposed area 11 formed with a stepped area 12. The stepped area 12 has a number of steps 13.

[0042] An opening 15 is formed in each step 13. The openings 15 form a step opening row 14. In this embodiment, the stepped triangle configured as the first wall portion 10 has seven steps.

[0043] The second wall portion 20 is a rectangular wall portion that also has an upper exposed region 21. In the upper exposed region 21, a first wall portion opening row 22 having a plurality of openings 23 is formed.

[0044] The third wall 30 is also a rectangular wall, and similarly has an upper exposed region 31. In the upper exposed region 31, a second wall opening row 32 having a plurality of openings 33 is formed.

[0045] As can be seen particularly from FIG. 2, the size of the second wall portion 20 is smaller than the size of the third wall portion 30.

[0046] The openings 23 in the second wall 20 are arranged along a straight line. The openings 33 in the third wall 30 are also arranged along a straight line. In this case, the openings in the second and third walls are arranged so that the straight line formed by the openings 23 and the straight line formed by the openings 33 intersect at a right angle.

[0047] As can be seen particularly from FIG. 2, the first wall 10 is disposed perpendicular to the second wall 20. The second wall 20 is also disposed perpendicular to the third wall 30. As a result, the first wall 10 and 3rd wall 30 are parallel to each other.

[0048] Furthermore, the first wall 10, the second wall 20 and the third wall 30 are spaced apart from the respective ends 81, 82, 83 of the base plate 8 along their respective longitudinal sides. wall part Only one end region of 30 extends to fourth end 84 (see FIG. 2).

[0049] To reduce weight, the base plate 8 has a larger central hole and a number of slots (not numbered).

[0050] Arranged below the base plate 8 is a reinforcing element 7 having a first slat 71 and a second slat 72. These two slats 71, 72 are arranged in a cross shape and reinforce the base plate 8 and thus the measuring body 2. Furthermore, the reinforcing element 7 makes it possible to clamp the measuring body 2 on the machine table 6 in a simple manner. In particular, this prevents the introduction of undesired stresses into the base plate or the three walls 10, 20, 30 during the clamping process, which could distort the measurement results.

[0051] Furthermore, the measurement body 2 has a first aperture row 101, a second aperture row 102, and a third aperture row 103 on the upper side of the base plate. The first aperture row 101 has a plurality of apertures 101a arranged on a first straight line 111. The first straight line 111 extends parallel to the first end 81. The second aperture row 102 has a plurality of apertures 102a arranged on a second straight line 112. In this case, the second aperture row 102 is parallel to the second end 82. The third aperture row 103 has a plurality of apertures 103a arranged on a third straight line 113. The third aperture row 103 is parallel to the third end 83 (see FIG. 3). In FIG. 3, for easier understanding, reference symbols are not assigned to all apertures in the first aperture row, second aperture row, and third aperture row.

[0052] 3, the first opening row 101 is parallel to the step opening row 14. The second opening row 102 is parallel to the first wall opening row 22 of the second wall 20. The third opening row 103 is parallel to the second wall opening row 32.

[0053] Preferably, the number of apertures in the first, second and third rows of apertures is the same, as is the geometric size and in particular the spacing between the apertures.

[0054] It should be noted that strip-shaped polishing reference surfaces (not shown in FIG. 3) may be provided adjacent to and parallel to each of the three rows of apertures, for example.

[0055] Furthermore, the first opening row 101, the second opening row 102, and the third opening row 103 are provided so that one opening is provided at each corner of the base plate 8.

[0056] More preferably, the thickness of the base plate 8 is the same as the wall thickness of the walls 10 , 20 , 30 .

[0057] The measuring body 2 is arranged on a machine table 6 of the three-axis machine tool 1. Furthermore, a 3D measuring sensor is arranged on the spindle 4, which measures the actual coordinates of the three-axis machine tool using the measuring body 2.

[0058] The three-axis machine tool 1 further comprises a control unit 9 configured to control the three-axis machine tool. The control unit 9 is further configured to perform corrections of the geometric data of the three-axis machine tool 1 based on a target / actual comparison of the geometric dimensions of the measurement body 2.

[0059] As already mentioned, a three-axis machine tool has three linear axes, specifically, a first axis in the X direction, a second axis in the Y direction, and a third axis in the Z direction.

[0060] Overall, there are 21 types of deviations in the three linear axes, three of which are perpendicularity deviations of the linear axes relative to each other. Thus, for a three-axis machine tool, there are a total of 21 error parameters.

[0061] In this way, the method according to the present invention can inspect and correct all deviations, including straightness deviation, rotation deviation and squareness deviation, of a three-axis machine tool.

[0062] To this end, the measurement body 2 is first measured using a coordinate measuring machine (not shown) to generate target values. These target values ​​are then provided to the control unit 9 of the three-axis machine tool 1 and stored in memory. In this case, to measure the measurement body 2, a coordinate system is set up so that the XY plane is parallel to the base plate 8. In this way, the geometry of the measurement body 2, which is preferably made of Invar, is determined based on the Z-, X-, and Y-positions of various basic elements of the measurement body 2 obtained by multiple measurements. At the same time, the zero position of the coordinate system of the measurement body 2 is also determined. For example, the polished step surface or the polished reference surface serves as the reference element for the Z-position. The openings in the opening rows 101, 102, and 103, the opening 15 in the step 13, and the openings 23 and 33 in the exposed areas 11 and 21 serve as reference elements for the X- and Y-positions.

[0063] To detect the geometric deviation of a three-axis machine tool, a measuring body 2 is introduced onto a machine table 6 in the workspace 3 of the three-axis machine tool. The measuring body 2 is clamped or otherwise fixed to the machine table. The XYZ coordinate system of the measuring body must be aligned parallel to the XYZ coordinate system of the three-axis machine tool. The measuring body 2 is then measured on the three-axis machine tool by a 3D measuring device 5, e.g., a 3D measuring sensor. Modern three-axis machine tools are typically equipped with this type of 3D measuring sensor, for example, to detect part position and part geometry.

[0064] In this way, before measurement, the coordinate system of the three-axis machine tool is arranged to be identical to the coordinate system of the coordinate measuring machine that previously measured the measurement body 2.

[0065] After fixing the measuring body 2 in the workspace 3 of the three-axis machine tool, the control unit 9 preferably allows the execution of a fully automatically executed NC program to measure the actual values ​​of the three-axis machine tool 1 by measuring the measuring body 2 with the 3D measuring sensor 5.

[0066] During the measurement of the measuring body 2 in the workspace 3 of the three-axis machine tool, the temperature of the workspace 3 of the three-axis machine tool 1 is preferably also detected and saved. If the temperature of the workspace differs from a reference temperature, e.g., 20°C, the thermal expansion coefficient of the workpiece must be taken into account when machining the workpiece on the three-axis machine tool. Here, a corresponding correction must be made to the actual values ​​of the three-axis machine tool.

[0067] After completing the measurement of the measuring body 2 on the three-axis machine tool 1 and, if necessary, adjusting the actual values ​​with respect to temperature, the actual values ​​of the three-axis machine tool can be measured and compared with the target values ​​of the measuring body. In this way, geometric deviations in the form of position deviations, straightness deviations, and squareness deviations of the three-axis machine tool can be calculated and checked and corrected by comparing the target values ​​with the actual values. In this case, by way of example, Figure 3 shows the straightness deviation G, squareness deviation R (angle α), and position deviation P in a plan view of the measuring body 2.

[0068] For example, the positional deviation in the X-axis can be determined by first evaluating the difference between the actual position and the target position in the X-direction of a measured reference element along the X-axis on the base plate 8. Since the zero position of the measuring body 2 and the relative position of the reference element with respect to the zero position are known, the measured difference can be related to the X-axis position of the three-axis machine tool. A table is therefore created of the X-axis positions of the three-axis machine tool and the positional deviations in the X-direction at these X-axis positions. In this case, these positional deviations are stored and directly used in the control unit 9 as correction data or error compensation for the three-axis machine tool.

[0069] Alternatively, the deviation can be mathematically pre-processed. For example, the deviation can be approximated using various mathematical functions. To be precise, in the case of a small measuring body 2 having only a few reference elements, it is conceivable to approximate the difference using, for example, a straight line (best fit). In this case, only scaling errors are corrected.

[0070] Since the measuring body 2 covers only a part of the workspace 3 of the three-axis machine tool, the detected actual values ​​are preferably extrapolated by a corresponding mathematical function, so that the deviations of the entire workspace 3 of the three-axis machine tool 1 are obtained.

[0071] Similarly, the straightness deviation G in the X axis is determined. In this case, the position deviation P in the Y or Z direction is related to the X direction position. In this case, the difference between the actual position and the target position in the Y direction is determined from the centers measured at the openings in the three opening rows 101, 102, and 103 and the reference openings in the first wall portion 10, the second wall portion 20, and the third wall portion 30. The difference between the actual position and the target position in the Z direction is determined, for example, from the reference surface of the base plate 8 and the polished surface of each step portion 13. In this case, too, mathematical preprocessing or approximation is possible.

[0072] After the correction data for the X-axis position deviation and straightness deviation are calculated, all of the measurement data for the actual position of the reference element are adjusted for further evaluation based on the correction data for the X-axis position deviation, the X-axis straightness deviation in the Y direction, and the X-axis straightness deviation in the Z direction. At this point, it is desirable to assume that the actual position after adjustment does not contain any error in the X direction. As a result, the error in the X direction can be ignored in further evaluation.

[0073] In a next step, the squareness error R between the X and Y axes can be calculated. For this purpose, two best-fit lines are calculated. The first best-fit line is obtained from the X-axis positions of the reference elements on the base plate 8 along the X direction and their positional deviations in the Y direction. The second best-fit line is obtained from the Y-axis positions of the reference elements on the base plate 8 along the Y direction and their positional deviations in the X direction. The angle α between the two best-fit lines is then calculated (see FIG. 3). In this case, the measured deviation can be used directly as a correction value for error correction in the control unit 9.

[0074] Next, the actual positions of all reference elements in the measurement data are adjusted according to their Y positions based on the squareness error so that the measurement data does not contain any XY squareness error.

[0075] Subsequently, the position and straightness deviations of the Y-axis are calculated, as in the case of the X-axis. For this purpose, the difference between the actual position of a reference position along the Y-axis on the base plate 8 and the target position is evaluated (see Figure 3). Along with the zero position, a table is obtained which contains the Y-axis positions of the three-axis machine tool and the positional deviations in the X, Y and Z directions at these Y-axis positions. As in the case of the X-axis, the data can be further processed in the control unit 9 or can be used directly as compensation data for error compensation of the three-axis machine tool. Here too, the compensation data must be extrapolated using corresponding mathematical functions to define the entire workspace 3.

[0076] After that, the actual positions of all reference elements are adjusted based on the correction data of the position error in the Y axis and the two straightness errors for further evaluation. At this point, it is desirable to assume that the actual positions after adjustment do not contain any error in the Y direction. As a result, the error in the Y direction can be ignored in further evaluation. As an example, Figures 4, 5, and 6 show the measurement of the pitch error of the X axis (Figure 4), the measurement of the roll error of the X axis (Figure 5), and the measurement of the yaw error of the X axis (Figure 6).

[0077] To be able to measure the X-axis yaw error (Figure 6), geometric features must exist in the X direction and their X positions must be detectable using a measurement sensor. To be able to measure the error independently of other errors, the features must have identical Y and Z positions. To be able to measure the effect of the X-yaw error, measurements must also be taken at different Y positions than those of the initial X feature series. Furthermore, the Y spacing d from the initial X feature series must be known (see Figure 6).

[0078] In the next step, the pitch error in the X axis is calculated. To measure the pitch error in the X axis (Figure 4), geometric features must exist in the X direction and their X positions must be detectable using a measurement sensor. To measure the error independently of other errors, the features must have identical Y and Z positions. To be able to measure the effect of the X pitch error, measurements must also be taken at different Z positions than those of the initial X feature series. Furthermore, the Z spacing d from the initial X feature series must be known.

[0079] To measure the X-axis roll error (Figure 5), geometric features must be present in the X direction and their Y positions must be detectable using a measurement sensor. To measure the error independently of other errors, the features must have identical Y and Z positions. To be able to measure the effect of the X-roll error, measurements must also be taken at different Z positions than the initial X feature series. Furthermore, the Z spacing d from the initial X feature series must be known (see Figure 5).

[0080] Measurement of the roll and yaw errors in the Y axis is performed according to the measurements shown in FIGS.

[0081] In the next step, the perpendicularity between the X-axis and the Z-axis is calculated. For this purpose, two best-fit lines are calculated. The first best-fit line is obtained from the X-axis positions of the reference elements on the base plate 8 along the X-direction and their positional deviations in the Z-direction. The second best-fit line is obtained from the Z-axis positions of the reference elements on the first wall 10 (step-like triangle) along the X-direction and their positional deviations in the X-direction. Next, the angle α between the two best-fit lines is calculated. The measured deviations can be used directly as correction values ​​for error correction in the control unit 9.

[0082] Similarly, the perpendicularity between the Y-axis and the Z-axis is calculated. In this case, a first line of best fit is obtained from the Y-axis positions of the reference elements on the base plate 8 along the Y direction and their positional deviations in the Z direction. A second line of best fit is obtained from the Z-axis positions of the reference elements on the second wall portion 20 along the Y direction and their positional deviations in the Y direction. The perpendicularity deviation between these two lines can also be used directly as a correction value for error correction.

[0083] Then, the actual positions of all reference elements in the measurement data are adjusted according to their Z positions based on the squareness error so that the measurement data contains neither XZ squareness error nor XY squareness error.

[0084] In a further step, the geometric deviation of the Z axis is calculated. For this purpose, the reference elements (reference openings and polished step surfaces) of the three walls 10, 20, 30 are used. Since the errors of the X and Y axes and the three types of squareness errors have already been removed from the measurement data in the above evaluation, it is assumed in this step that the displacements in the X or Y direction, which are necessary for measuring the steps, do not affect the geometric deviation of the Z axis.

[0085] Thus, by evaluating the difference between the actual and target positions of the reference position in the Z direction on the first wall 10, the position deviation in the Z axis is measured. Since the zero position of the measuring body 2 and the relative position of the reference element with respect to the zero position are known, the measured difference can be related to the Z axis position of the three-axis machine tool. A table of Z axis positions is thus obtained, which can be used directly as correction data or error compensation for the three-axis machine tool. As with the X and Y axes, the data can be further processed or used directly as correction data. Here too, it can be extrapolated to correction data using corresponding mathematical functions.

[0086] As with the other axes, the squareness deviation of the Z axis is measured in a similar manner. In this case, the position deviation in the Y or X axis direction is correlated with the Z axis position. In this case, the difference between the actual position and the target position is determined from the measured center of the aperture. Further processing of the straightness deviation can be performed in the same way as for the Z axis position deviation.

[0087] In this way, with the help of the measuring body 2, all relevant geometric errors, including those in the yaw, pitch, and roll directions, can be checked and corrected. The method is particularly suitable for correcting geometric errors of three-axis machine tools when thermal conditions change, since linear errors typically occur in such cases and can be easily extrapolated. Furthermore, the method can also be used to adjust the geometry of three-axis machine tools to materials with different thermal expansion coefficients when the workspace is at temperatures different from the reference temperature.

[0088] In addition to the above description of the invention, explicit reference is made herein to the illustrations of the invention in Figures 1-6 for additional disclosure of the invention. [Explanation of symbols]

[0089] 13 axis machine tool 2 Measurement object 3. Workspace 4 spindles 5. Measuring device (3D measuring sensor) 6 Machine Table 7 Reinforcing Elements 8 base plate 9 Control Unit 10 1st wall section 11 Upper exposed area 12 Stepped area 13 Step section 14 Step opening row 15 Aperture 20 Second wall section 21 Upper exposed area 22 1st wall opening row 23 Aperture 30 Third wall 31 Upper exposed area 32 2nd wall opening row 33 Aperture 71 First slat 72 Second slat 81 First end 82 Second end 83 Third end 84 4th end 101 First Aperture Row 101a aperture 102 Second Aperture Row 102a aperture 103 3rd Opening Row 103a aperture 111 1st straight line 112 Second straight line 113 3rd straight line d-spacing G Straightness deviation R squareness error P position deviation XX axis YY axis ZZ axis α Squareness deviation

Claims

1. A measuring body for inspecting geometric deviations in a three-axis machine tool (1), comprising: A base plate (8); a first wall portion (10) disposed on the base plate (8) and protruding perpendicularly from the base plate (8); a second wall portion (20) disposed on the base plate (8), protruding perpendicularly from the base plate (8), and disposed orthogonal to the first wall portion (10); A first row of openings (101) and a second row of openings (102) are formed in the base plate (8), The first wall portion (10) has a stepped triangular shape and includes a stepped region (12) having a plurality of steps (13) in an upper exposed region (11); The second wall (20) is a square wall having a first wall opening row (22) in an upper exposed area (21) extending parallel to the base plate (8); The measuring body, wherein the first opening row (101) is arranged parallel to the step opening row (14), and the second opening row (102) is arranged parallel to the first wall opening row (22).

2. The stepped region (12) comprises the step opening row (14), 2. The measuring body according to claim 1, wherein each step (13) is formed with, in particular, an opening (15) and a ground reference surface.

3. Further, a third wall portion (30) is disposed on the base plate (8) and protrudes perpendicularly from the base plate (8), The third wall portion (30) is disposed perpendicular to the second wall portion (20), 3. The measuring body according to claim 2, wherein the third wall portion (30) has a second wall portion opening row (32) consisting of a plurality of openings (33) in an upper exposed region (31).

4. 4. The measuring body according to claim 3, wherein the first wall portion (10), the second wall portion (20), and the third wall portion (30) are arranged in a U-shape on a base plate.

5. 4. The measuring body according to claim 3, further comprising a third row of openings (103) in the base plate (8) extending parallel to the second row of wall openings (32).

6. 6. The measuring body according to claim 5, wherein each of the first opening row (101), the second opening row (102), and the third opening row (103) extends along one end of the base plate (8), and one of the openings in the opening row is arranged at each corner of the base plate (8).

7. the first wall portion (10), the second wall portion (20), and the third wall portion (30) are disposed on the base plate (8) at intervals from a first end (81), a second end (82), and a third end (83); The measurement body according to claim 5 , wherein the interval is at least twice the diameter of the openings in the first opening row, the second opening row, and the third opening row.

8. 6. The measuring body according to claim 5, wherein a polished surface is present in addition to the openings of the step portion (13), and / or a polished surface is formed in addition to the openings of the first opening row and / or the second opening row and / or the third opening row.

9. 2. The measuring body according to claim 1, further comprising a reinforcing element (7) arranged on the underside of the base plate (8) for mechanically reinforcing the base plate (8) and / or arranged on the machine tool as a clamping aid.

10. A three-axis machine tool, a tool spindle (4); A measuring body (2) according to any one of claims 1 to 9, a measuring device (5) that can be clamped to the tool spindle (4) and that is configured to detect an actual value of the measuring body (2) that is fixed to the three-axis machine tool (1); a control unit (9) configured to control the three-axis machine tool (1), The control unit (9) is further configured to perform a target / actual comparison based on a geometric target value of the dimension of the measurement body (2) and an actual value of the measurement body (2) fixed to the three-axis machine tool (1) measured for the three-axis machine tool (1) by a measuring device (5), and to correct the geometric data of the three-axis machine tool (1) in the control program of the control unit (9) if a deviation occurs between the target value and the actual value.

11. 11. The three-axis machine tool according to claim 10, wherein the control unit (9) comprises a memory in which the setpoint values ​​of the measuring body (2) are stored.

12. 1. A method for inspecting and correcting geometric deviations in a three-axis machine tool, comprising: clamping a measuring device (5) to a tool spindle (4) of the three-axis machine tool; a step of placing the measuring body (2) according to any one of claims 1 to 9 in a working space of the three-axis machine tool; accessing a plurality of positions of the measuring body (2) to acquire geometric actual data of the three-axis machine tool using the measuring body (2); - performing a target / actual comparison between the geometric actual data of the measuring body (2) and stored target data in order to measure the geometric deviation; and correcting the geometric deviation in a control unit (9) of the three-axis machine tool.

Images