Measuring body for geometric deviation inspection of a three-axis machine tool, three-axis machine tool, and method for correcting geometric deviation of a 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 Art

[0002] An area known as a problem in the case of a machine tool is the geometric accuracy of the machine tool. The geometric accuracy of a machine tool is measured by the relative deviation of the actual position and orientation of the machine with respect to the target position and orientation of the workpiece. This error causes a deviation from the ideal workpiece shape dimensions, and ultimately leads to a decrease in the operating accuracy of the machine tool. In order to improve geometric accuracy, generally, the deviation of each axis and the relative position and orientation of each axis with respect to each other are considered.

[0003] Assuming a rigid body model, in the case of a three-axis machine tool in this case, there are three types of linear deviations (one type in the axial direction and two types in the direction orthogonal to the axial direction) and three types of rotational direction deviations (yaw direction, pitch direction, roll direction). Therefore, six types of deviations occur for each linear axis, that is, 18 types of deviations occur for the three linear axes. Furthermore, it is necessary to consider three types of right angle deviations of the linear axes with respect to each other. In this way, a total of 21 types of geometric errors can exist in a three-axis machine tool. In this case, the individual deviations may overlap with each other, resulting in an actually significant overall error and possibly having an undesirable influence on the geometric accuracy of the machine tool.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a measuring body for inspecting geometric deviations of a three-axis machine tool, a three-axis machine tool, which are configured as simply and cost-efficiently as possible, and a method for inspecting and correcting geometric deviations of a three-axis machine tool that can be carried out as cost-efficiently and quickly as possible.

Means for Solving the Problems

[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 show further preferred developments of the invention.

[0006] In contrast, the measuring body for geometric deviation inspection of a three-axis machine tool according to the 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 has no linear deviation, rotational deviation, or squareness deviation. Accordingly, a workpiece can be machined by the three-axis machine tool with the highest possible level of accuracy. In this case, the correction data obtained based on the measuring body can be used directly for error correction of the three-axis machine tool. The measuring body is particularly suitable for machine tools for ultra-high-precision machining. This measuring body is also particularly suitable for inspection, correction, and long-term evaluation of machine tools, so that the machine tool can be used for ultra-precision machining throughout its service life.

[0007] This is achieved by the invention in that the measuring body comprises a base plate, a first wall portion, and a second wall portion. The first wall portion is arranged on a base plate that is particularly square and projects vertically from the base plate. The first wall portion is a stepped triangle and has a stepped region with a plurality of steps in an upper exposed region. Further, the second wall portion is quadrilateral and is arranged to project vertically on the base plate and to be arranged orthogonally to the first wall portion. Further, a first opening row and a second opening row are formed in the base plate. In this way, the first wall portion is configured in a stepped manner with a plurality of steps on the side facing away from the base plate. The second wall portion is a square wall, particularly a rectangular wall, and has an upper exposed region parallel to the base plate, and a first wall portion opening row is formed in this exposed region.

[0008] Thus, the stepped region of the first wall portion exists in the upper exposed region of the first wall portion. Therefore, the upper exposed region of the first wall portion forms a stepped portion that enables detection of different positions in the Z direction, and the base plate extends over the base planes in the X and Y directions. Due to the stepped upper exposed region of the first wall portion, the first wall portion substantially has a triangular shape.

[0009] It is particularly preferable that the stepped first wall portion includes a stepped opening row in which one opening is formed in each stepped portion. Thereby, in addition to measuring the position in the Z direction, it becomes possible to detect the positions in the X and Y directions at different heights.

[0010] It is more preferable that the measuring body is disposed on the base plate and has a third wall portion positioned orthogonal to the second wall portion. The third wall portion is, like the second wall portion, a rectangular wall having an upper exposed region extending parallel to the base plate, and includes a second wall portion opening row. Therefore, the third wall portion is disposed on the base plate in parallel with the first wall portion. Thus, the first wall portion opening row and the second wall portion opening row are arranged orthogonal 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 more preferable that the measuring body has a third opening row parallel to the second wall portion opening row of the third wall portion on the base plate.

[0012] Preferably, the first opening row, the second opening row, and the third opening row each extend above the base plate along one end portion of the base plate, which is particularly preferably configured in a rectangular shape. Therefore, it is preferable that the first opening row is parallel to the first end portion of the base plate, the second opening row is parallel to the second end portion of the base plate, and the third opening row is parallel to the third end portion of the base plate.

[0013] Particularly preferably, 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, the measuring body can detect yaw direction error, pitch direction error, and roll direction error.

[0014] The first opening row, the second opening row, and the third opening row preferably have the same number of openings, the same interval between openings, and the same opening diameter.

[0015] According to a more preferred embodiment of the present invention, the first wall portion, the second wall portion, and the third wall portion are arranged at a predetermined interval from the first end portion, the second end portion, and the third end portion, respectively.

[0016] The stepped surface of the stepped portion of the stepped triangle is parallel to the base plate, and it is more preferable that it is precisely machined by polishing or other methods to achieve excellent flatness. The upper exposed regions of the second wall portion and / or the third wall portion are also preferably polished or precisely machined to exhibit excellent flatness. As a result, the accuracy of measurement using the measuring body can be significantly improved.

[0017] In the base plate, the region 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 are more preferably provided as a polishing region.

[0018] The measuring body more preferably has a reinforcing element on the lower side of the base plate to improve the stability of the measuring body. The reinforcing element is preferably a slat cross including two slats, and each slat connects two opposite corners of the base plate on the lower side of the base plate. The reinforcing element is preferably also used to clamp the measuring body in a machine tool.

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

[0020] The base plate is preferably quadrilateral, particularly square. More preferably, each opening row, step portion opening row, and each row of the first wall portion opening row and the second wall portion opening row of the base plate are provided with at least one reference opening. The peripheral area of each reference opening is preferably polished, and as a result, the polished surface can be used as a reference element for defining the Z coordinate. The center of each reference opening can be used as a reference element for the X coordinate and the Y coordinate.

[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 manufactured from invar. Invar has a very low coefficient of thermal expansion and is particularly suitable for manufacturing the measuring body. More preferably, the thicknesses of the first wall portion, the second wall portion, and the third wall portion are the same as the thickness of the base plate.

[0023] Furthermore, the present invention relates to a three-axis machine tool comprising a tool spindle, a measuring device that can be clamped in the tool spindle, particularly a 3D measurement sensor, and a control unit for controlling the three-axis machine tool. The three-axis machine tool is provided with the 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 a predetermined geometric target dimension of the measuring body and the geometric actual dimension of the measuring body measured by the measuring device in the three-axis machine tool. Therefore, the control unit has a memory for storing the geometric target dimension of the measuring body obtained by the measuring device in the previous process. When measuring the geometric actual dimension of the measuring body in the three-axis machine tool, it is preferable that the control unit starts an NC program for measuring the measuring body in order to measure the actual value of the measuring body. In this way, the geometric data of the three-axis machine tool is corrected by comparing the target value and the actual value, and as a result of the correction, the accuracy during machining of a workpiece using the three-axis machine tool is significantly improved. Therefore, correction of the geometric error of the three-axis machine tool can be realized in a simple manner. The target value is preferably stored in the memory.

[0024] Furthermore, the present invention relates to a method for inspecting and correcting geometric deviations in a three-axis machine tool, the method comprising: - clamping a measuring device, in particular a 3D measuring sensor, to the spindle of the three-axis machine tool; - arranging a measuring body according to the invention in the working space of the three-axis machine tool, in particular by clamping a reinforcing element; - bringing the measuring device close to different positions of the measuring body in order to obtain geometric actual data in the measuring body; - performing a target / actual comparison between the obtained actual data of the measuring body and predefined target data in order to measure geometric deviations, in particular linear deviations, rotational deviations and squareness deviations; - correcting the geometric deviations of the three-axis machine tool in the control unit of the three-axis machine tool in order to improve the machining accuracy of the three-axis machine tool. The method includes the steps above.

[0025] In this case, the method according to the invention can be carried out relatively quickly and reliably. In particular, the method according to the invention can also be carried out in a short time at the customer's site 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 after the three-axis machine tool has been delivered.

[0026] Of course, this method can also be carried out at 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 a coordinate measuring device, and then the measuring body is arranged in the working space 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 working space during the measurement of the measuring body on the three-axis machine tool and correct the actual data based on the detected temperature of the working space. Thereby, the accuracy of the correction of geometric deviations is further improved.

[0029] The method according to the present invention is preferably useful for the inspection, correction, and long-term evaluation of a three-axis machine tool. In this case, the method according to the present invention preferably - the positional deviation in each case (parallel displacement of each axis (three possible errors because there are three axes)), - two straightness deviations for each axis (parallel displacement in the transverse direction with respect to the axial direction), that is, a total of six possible geometric errors, and - three rotational deviations for each of the three axes, that is, deviations in the yaw direction, pitch direction, and roll direction (that is, nine geometric deviations), - three squareness deviations of the linear axes X, Y, and Z with respect to each other (X-Y squareness deviation, X-Z squareness deviation, Y-Z squareness deviation) measures 21 possible geometric errors.

[0030] It should be noted that due to the design and kinematics of the three-axis machine tool, individual errors can also be ignored. Preferably, the pitch direction error of the Y axis is corrected by the positioning error in the Y direction, the straightness error of the Y axis with respect to the X direction, and the squareness error between the Y axis and the X axis. In this case, the precondition is that the interval in the X direction from the table of the machine tool to the spindle is constant. More preferably, the roll direction error of the Z axis is ignored because the tool rotates on this axis. More preferably, when the length of the tool is constant, the pitch direction error and yaw direction 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. Thus, the complexity of the measurement is reduced by this measurement.

Brief Description of the Drawings

[0031] Preferred embodiments of the present invention will be described with reference to the following drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0032] Hereinafter, with reference to FIGS. 1 to 6, 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.

[0033] Furthermore, with reference to FIGS. 1 to 6, a method for inspecting and correcting the geometric deviation of the three-axis machine tool will be described.

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

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

[0036] Details of the measuring body 2 are shown in FIGS. 1 to 3. The measuring body 2 is configured to inspect the geometric deviation of the three-axis machine tool. By clamping the measuring body once, all 21 types of errors including linear error, rotational error, and straightness error can be measured. 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 includes a planar base plate 8 that extends in the X direction and the Y direction on the base surface. 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, protrude vertically from the base plate 8, and 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 includes a first end portion 81, a second end portion 82, a third end portion 83, and a fourth end portion 84.

[0041] Particularly as can be seen from FIGS. 1 and 2, the three wall portions 10, 20, and 30 are geometrically configured differently. In this case, the first wall portion 10 is a stepped triangle having an upper exposed region 11 in which a stepped region 12 is formed. The stepped region 12 has a plurality of stepped portions 13.

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

[0043] The second wall portion 20 is a rectangular wall portion having an upper exposed region 21 in the same manner. A first wall portion opening row 22 having a plurality of openings 23 is formed in the upper exposed region 21.

[0044] The third wall portion 30 is also a rectangular wall portion and has an upper exposed region 31 in the same manner. A second wall portion opening row 32 having a plurality of openings 33 is formed in the upper exposed region 31.

[0045] Particularly as can be seen 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 of the second wall portion 20 are arranged along a straight line. The openings 33 of the third wall portion 30 are also arranged along a straight line. In this case, the openings of the second wall portion and the third wall portion are arranged such 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 portion 10 is arranged at a right angle to the second wall portion 20. The second wall portion 20 is also arranged at a right angle to the third wall portion 30. As a result, the first wall portion 10 and the third wall portion 30 are parallel to each other.

[0048] Furthermore, the first wall portion 10, the second wall portion 20, and the third wall portion 30 are arranged at intervals from the respective end portions 81, 82, 83 of the base plate 8 along the respective longitudinal side surfaces. Only one end region of the third plate 30 extends to the fourth end portion 84 (see FIG. 2).

[0049] For weight reduction, the base plate 8 has a larger central hole portion and a plurality of elongated hole portions (not shown).

[0050] Below the base plate 8, a reinforcing element 7 having a first slat 71 and a second slat 72 is arranged. These two slats 71, 72 are arranged in a cross shape, reinforcing the base plate 8 and thus the measuring body 2. Furthermore, the reinforcing element 7 enables the measuring body 2 to be clamped onto the machine table 6 in a simple manner. In particular, this prevents the introduction of undesirable stresses into the base plate or the three wall portions 10, 20, 30 that could distort the measurement results during the clamping process.

[0051] Furthermore, the measuring body 2 has, on its upper side in the base plate, a first opening row 101, a second opening row 102, and a third opening row 103. The first opening row 101 has a plurality of openings 101a arranged on a first straight line 111. The first straight line 111 extends parallel to the first end portion 81. The second opening row 102 has a plurality of openings 102a arranged on a second straight line 112. In this case, the second opening row 102 is parallel to the second end portion 82. The third opening row 103 has a plurality of openings 103a arranged on a third straight line 113. The third opening row 103 is parallel to the third end portion 83 (see FIG. 3). In FIG. 3, for the sake of clarity, reference signs are not given to all the openings of the first opening row, the second opening row, and the third opening row.

[0052] As can be further seen from FIG. 3, the first opening row 101 is parallel to the stepped portion opening row 14. The second opening row 102 is parallel to the first wall portion opening row 22 of the second wall portion 20. The third opening row 103 is parallel to the second wall portion opening row 32.

[0053] In the first opening row, the second opening row, and the third opening row, it is preferable that the number of openings is the same, similar to the geometric sizes, particularly the intervals between the openings.

[0054] It should be noted that strip-shaped polishing reference surfaces (not shown in FIG. 3) can be provided, for example, in parallel adjacent to these three rows of opening rows respectively.

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

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

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

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

[0059] As already described, the 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, 21 types of deviations occur in the three linear axes, and among them, 3 types are the angular deviations of the linear axes with respect to each other. Thus, in the three-axis machine tool, there are a total of 21 error parameters.

[0061] Thus, by the method according to the present invention, it is possible to inspect and correct all deviations of the straightness deviation, rotational deviation, and squareness deviation of the three-axis machine tool.

[0062] Therefore, first, in order to generate a target value, the measuring body 2 is measured by a coordinate measuring device (not shown). Then, the target value is provided to the control unit 9 of the three-axis machine tool 1 and stored in the memory. In this case, in order to measure the measuring body 2, the coordinate system is installed such that the XY plane is parallel to the base plate 8. In this way, the shape and dimensions of the measuring body 2, preferably manufactured by Invar, are obtained based on the Z positions, X positions, and Y positions of various basic elements of the measuring body 2 obtained by multiple measurements. At the same time, the zero position of the coordinate system of the measuring body 2 is also specified. For example, the polished step surface or the polishing reference surface serves as a reference element for the Z position. The openings of the opening rows 101, 102, 103, the opening 15 of the step portion 13, and the openings 23, 33 of the exposed regions 11, 21 serve as reference elements for the X position and the Y position.

[0063] Here, in order to detect the geometric deviation of the three-axis machine tool, the measuring body 2 is introduced onto the machine table 6 in the working space 3 of the three-axis machine tool. In this case, the measuring body 2 is fixed on the machine table by a clamp or other means. In this case, the XYZ coordinate system of the measuring body needs to be arranged in parallel with the XYZ coordinate system of the three-axis machine tool in principle. Then, the measurement of the measuring body 2 in the three-axis machine tool is performed by a 3D measuring device 5, for example, a 3D measuring sensor. Typically, modern three-axis machine tools are equipped with this type of 3D measuring sensor to detect, for example, the part position and part shape and dimensions.

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

[0065] After fixing the measuring body 2 in the working space 3 of the three-axis machine tool, it is preferable that the control unit 9 permits the execution of an NC program that is fully automatically executed in order 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] While measuring the measuring body 2 in the working space 3 of the three-axis machine tool, it is preferable to detect and store the temperature of the working space 3 of the three-axis machine tool 1. When the temperature of the working space is different from a reference temperature of, for example, 20°C, the coefficient of thermal expansion of the workpiece, which is the object to be machined on the three-axis machine tool, must be considered in the machining. Here, it is necessary to execute corresponding corrections to the actual values of the three-axis machine tool.

[0067] After the measurement of the measuring body 2 in the three-axis machine tool 1 and the completion of the adjustment of the actual values related to the temperature as necessary, the actual values of the three-axis machine tool are measured and can be compared with the target values of the measuring body. In this way, geometric deviations in the form of position deviation, straightness deviation, and squareness deviation of the three-axis machine tool can be calculated and inspected and corrected by comparing the target values with the actual values. In this case, as an example, FIG. 3 shows the straightness deviation G, the squareness deviation R (angle α), and the position deviation P in the plan view of the measuring body 2.

[0068] For example, first, the position deviation of the X-axis can be determined by evaluating the difference between the actual position and the target position in the X direction of the 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 associated with the X-axis position of the three-axis machine tool. Therefore, a table of the X-axis positions of the three-axis machine tool and the position deviations in the X direction at these X-axis positions is created. In this case, these position deviations are stored and used as they are in the control unit 9 as correction data or error correction of the three-axis machine tool.

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

[0070] Since the measuring body 2 covers only a part of the working space 3 of the three-axis machine tool, the detected actual values are preferably extrapolated by the corresponding mathematical function. As a result, the deviation of the entire working space 3 of the three-axis machine tool 1 is obtained.

[0071] Similarly, the straightness deviation G of the X-axis is obtained. In this case, the position deviation P in the Y direction or the Z direction is associated with the X-direction position. In this case, the difference between the actual position and the target position in the Y direction is obtained from the centers measured at the openings of the three rows of opening rows 101, 102, 103 and the reference openings of the first wall portion 10, the second wall portion 20 and the third wall portion 30, respectively. The difference between the actual position and the target position in the Z direction is obtained from, for example, the reference surface of the base plate 8 and the polished surfaces of the respective stepped portions 13. Also in this case, mathematical pre-processing or approximation is possible.

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

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

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

[0075] Thereafter, similar to the case of the X-axis, the position deviation and straightness deviation of the Y-axis are calculated. For this purpose, the difference between the actual position and the target position of the reference position along the Y-axis on the base plate 8 is evaluated (see FIG. 3). Together with the zero position, a table including the Y-axis positions of the three-axis machine tool and the position deviations in the X, Y, and Z directions at these Y-axis positions is obtained. Similar to the case of the X-axis, the data can be further processed in the control unit 9 or used as it is as correction data for error correction of the three-axis machine tool. Here too, in order to define the entire working space 3, it is necessary to extrapolate the correction data using the corresponding mathematical function.

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

[0077] In order to be able to measure the yaw direction error of the X-axis (Figure 6), a group of geometric features must exist in the X direction and their X positions must be detectable using a measurement sensor. In order to be able to measure that error independently from other errors, the Y and Z positions of the feature group must be the same. In order to be able to measure the influence of the X yaw direction error, further measurements at a Y position different from that of the first X feature series are required. Furthermore, the Y interval d from the first X feature series must be known (see Figure 6).

[0078] In the next step, the pitch direction error of the X-axis is calculated. In order to measure the pitch direction error of the X-axis (Figure 4), a group of geometric features must exist in the X direction and their X positions must be detectable using a measurement sensor. In order to measure that error independently from other errors, the Y and Z positions of the feature group must be the same. In order to be able to measure the influence of the X pitch direction error, further measurements at a Z position different from that of the first X feature series are required. Furthermore, the Z interval d from the first X feature series must be known.

[0079] In order to measure the roll direction error of the X-axis (Figure 5), a group of geometric features must exist in the X direction and their Y positions must be detectable using a measurement sensor. In order to measure that error independently from other errors, the Y and Z positions of the feature group must be the same. In order to be able to measure the influence of the X roll direction error, further measurements at a Z position different from that of the first X feature series are required. Furthermore, the Z interval d from the first X feature series must be known (see Figure 5).

[0080] The measurement of the roll direction error and the yaw direction error on the Y-axis is carried out according to the measurements shown in Figures 4 and 5.

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

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

[0083] Then, the actual positions of all the reference elements in the measurement data are adjusted according to their Z positions based on the right angle error so that the measurement data does not include either the X-Z right angle error or the X-Y right angle 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 surface) of the three wall portions 10, 20, and 30 are used. Since the errors of the X-axis and the Y-axis and the three types of right angle errors have already been removed from the measurement data in the above evaluation, in this step, it is assumed that the displacements in the X direction or the Y direction, which are necessary for the measurement of the step portion, do not affect the geometric deviation of the Z-axis.

[0085] Therefore, by evaluating the difference between the actual position and the target position of the reference position in the Z direction on the first wall portion 10, the position deviation of 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 associated with the Z-axis position of the three-axis machine tool. Therefore, a table of Z-axis positions is obtained, and these positions can be used as they are for the correction data or error correction of the three-axis machine tool. Similar to the cases of the X-axis and Y-axis, the data can be further processed or used as it is as correction data. Here too, extrapolation can be performed on the correction data using the corresponding mathematical function.

[0086] Similar to the cases of other axes, the straightness deviation of the Z axis is similarly measured. In this case, the position deviation in the Y-axis direction or the X-axis direction is associated with the Z-axis position. In this case, the difference between the actual position and the target position is obtained from the measured center of the opening. Further processing of the straightness deviation can be performed in the same manner as the position deviation of the Z axis.

[0087] In this way, with the help of the measuring body 2, all relevant geometric errors including the yaw direction, pitch direction, and roll direction can be inspected and corrected. This method is particularly suitable for correcting the geometric errors of a three-axis machine tool when there are changes in the thermal conditions, because in such cases, generally linear errors occur, and these errors can be easily extrapolated. Furthermore, this method can also be used to adjust the shape and dimensions of the three-axis machine tool according to materials having various thermal expansion coefficients when the temperature inside the working space is different from the reference temperature.

[0088] In addition to the above description of the present invention, as additional disclosure of the present invention, this specification explicitly refers to the illustrations of the present invention in FIGS. 1 to 6.

Explanation of Reference Numerals

[0089] 1 Three-axis machine tool 2 Measuring body 3 Working space 4 Spindle 5 Measuring device (3D measuring sensor) 6 Machine table 7 Reinforcing element 8 Base plate 9 Control unit 10 First wall part 11 Upper exposed area 12 Staircase-like area 13 Step part 14 Step part opening row 15 Opening 20 Second wall part 21 Upper exposed area 22 First wall part opening row 23 Opening 30 Third wall part 31 Upper exposed area 32 Second wall part opening row 33 Opening 71 First slat 72 Second slat 81 First end 82 Second end 83 Third end 84 Fourth end 101 First opening row 101a Opening 102 Second opening row 102a Opening 103 Third opening row 103a Opening 111 First straight line 112 Second straight line 113 Third straight line d Spacing G Straightness deviation R Angular error P Position deviation X X-axis Y Y-axis Z Z-axis α Angular 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 vertically from the base plate (8); a second wall portion (20) disposed on the base plate (8), protruding vertically from the base plate (8), and arranged 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). Measuring body.

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

3. Furthermore, it includes a third wall portion (30) disposed on the base plate (8) and protruding vertically from the base plate (8); the third wall portion (30) is arranged to be orthogonal to the second wall portion (20); The measuring body according to claim 1 or 2, wherein the second wall portion (30) includes a second wall portion opening row (32) composed of a plurality of openings (33) in an upper exposed region (31).

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 the base plate.

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

6. Each row 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 of the opening row is disposed at each corner of the base plate (8). Measuring body according to claim 4 or 5.

7. The first wall portion (10), the second wall portion (20), and the third wall portion (30) are arranged on the base plate (8) at intervals from a first end portion (81), a second end portion (82), and a third end portion (83). The interval is more than twice the diameter of the openings of the first opening row, the second opening row, and the third opening row. The measuring body according to any one of claims 4 to 6.

8. In addition to the openings of the stepped portion (13), there is a polished surface, and / or in addition to the openings of the first opening row and / or the second opening row and / or the third opening row, a polished surface is formed. The measuring body according to any one of claims 1 to 7.

9. Furthermore, a reinforcing element (7) is provided which is arranged below the base plate (8) in order to mechanically reinforce the base plate (8) and / or which is arranged on the machine tool as a clamping aid. The measuring body according to any one of claims 1 to 8.

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

11. The control unit (9) comprises a memory in which the target value of the measuring body (2) is stored. The three-axis machine tool according to claim 10.

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

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