JP4908755B2 - Grinding machine calibration method and recalibration method and machine having a device for performing the method - Google Patents

Description

The present invention relates to a calibration method and a recalibration method of a grinding machine or an electric discharge machine or a machine that performs grinding and electric discharge machining, and a machine that realizes the method.

Grinding machines and / or electrical discharge machining machines are used for tool manufacture, for example with high precision. There is a growing demand for accurate machining. Such machining accuracy must be guaranteed not only in individual cases but also in mass production over a long period of time. This requires careful calibration and control of the individual machines. Calibration is valid over a long period of time and should be done in a simple manner.

The object of the present invention is to provide a calibration method for grinding or electrical discharge machining machines that ensures accurate machining of the tool over a long period of time. It is a further object of the present invention to provide a machine that implements such a method.

The above-mentioned problems are solved by the following grinding machine calibration and recalibration method. Namely, a calibration method and a recalibration method of a grinding machine or electric discharge machining machine having a workpiece spindle, a machine scanner, a workpiece carrier or a machine for performing grinding and electric discharge machining , wherein the workpiece spindle is a grinding tool or electric discharge machining Receiving a tool, the machine scanner being connected to a workpiece spindle carrier or a grinding machine head, a workpiece carrier for a workpiece comprising a workpiece receiving element, the workpiece spindle carrier and the workpiece The relative position with respect to the carrier can be adjusted relative to each other by the control device under the control of the control unit, and a memory unit is provided in the control unit for storing calibration values, Is fixed to the workpiece spindle carrier (3), and the test piece is the workpiece carrier. In the first step, the work spindle is provided with a reference body, the work receiving element is provided with a reference scanner, the reference body is provided with a drive unit for the work carrier and / or the work spindle carrier. And the resulting measurement value is stored in the memory unit, and in a second step, the work spindle is equipped with a grinding tool, the work receiving element is equipped with an object, The object is slightly ground from different directions in the grinding test. In the third step, the object is obtained from the difference in size of the plurality of ground parts created in the second step with respect to the circumferential direction of the object. The estimated correction value added to the measured value stored during the first step, or Replacing the measured value by a pile correction value, transmitting the correction value to a control unit, correcting the stored calibration value if the correction value exceeds an allowable value, and the step comprises the second step Returning to the step, if not, the step follows the fourth step, in which the test piece is scanned by a mechanical scanner, and the scanning result is defined in steps 1 to 3 above. It is solved by a calibration method and a recalibration method of the grinding machine, characterized in that it is adjusted to fit the measured value.

The method of the present invention is based on the following facts. That is, based on the fact that individual machines occasionally perform recalibration after the initial calibration, where this initial calibration is performed by a reference tracer and recalibration is performed by a machine scanner. ing. Calibration values obtained in the re-calibration method by a mechanical scanner represents the correction data. This correction data is stored and used by the machine control program to correct the axial motion of the grinding or electrical discharge machine in subsequent grinding or electrical discharge machining processes. Since recalibration is sometimes performed automatically as needed, this recalibration returns its accuracy to the initial calibration. This initial calibration is preferably performed using a reference scanner. This reference scanner is attached to the workpiece carrier. The reference body, i.e. the reference disk, is attached to the work spindle instead of electrical discharge machining or grinding tool attachment. Once this is achieved, the reference body is then scanned by the reference scanner several times. Thereby, at least one scanning process is preferably carried out for each coordinate direction X, Y, Z, respectively. This corresponds, for example, to the adjustment direction of the individual positioning device acting on the workpiece carrier or the work spindle carrier. As a result, initial measurement values are obtained for each coordinate direction. In particular, the measured value is obtained by subtracting the position value supplied by the adjusting device assigned to the individual coordinates with the size of the known reference disk and reference scanner. However, the measured value obtained by this is only a first order approximation. This is because the switch point of an advantageous switching reference scanner is usually not known accurately. The switch point of the scanner is initially arbitrarily assumed for the calculation, and under this assumption and the assumptions of the disk and scanner size and the coordinate values of the adjustment elements, the first correction value Δx, Δy and Δz are calculated. This correction value represents incomplete positioning caused by structural inaccuracies and thermal changes of the machine base and guide elements in each coordinate direction, and this correction value can be found in the control device or in the attached memory unit. Stored.

A grinding test is then carried out in a second step, in which the stored correction value is used for the correction control command of the adjusting device. Said value is applied in a coordinate direction predetermined for the grinding test, suitably in the sign direction. The specimen is slightly ground several times during the grinding test, in particular from two directions for each coordinate to be inspected. The portion to be ground is a small facet (cut surface) ground on the surface of the test piece. Two test parts to be ground and facets belonging to them, which belong to the same coordinate and are ground from different coordinate directions (ie + x and −x), are thereby arranged adjacent to each other. The positioning error between + x and -x is determined from the size difference. If the two facets are the same size, there is no positioning error. If these facets are of different sizes, the correction values Δx, Δy, Δz are derived from the size differences and then stored in the control device or memory unit. A second grinding test follows, which is again evaluated in the same way. This iteration is repeated until facets of the same size are ground in the individual coordinate directions. Usually, it is sufficient to perform this iterative process on one coordinate, ie on the coordinate X. This applies at least if the reference scanner used has the same switch point position in all radial directions relative to the lateral direction of its scan pin. The scanner correction values obtained for coordinate X (or other individually selected coordinates) can then be used for other remaining coordinates.

Once the grinding machine or electrical discharge machine has thus received its first calibration, a first recalibration is then carried out quickly and continuously in time. Here, a specimen in the machine is brought into contact with a mechanical scanner in the machine. Correction values Δxn, Δyn, Δzn obtained through this scanning test are stored here. These show the differences measured for the mechanical scanner compared to the reference scanner. A subsequent recalibration process is measured against the correction values obtained in the initial calibration. For example, if the values Δxs, Δys, Δzs for the three coordinate directions X, Y, Z are different from Δxn, Δyn, Δzn, these deviations represent, for example, changes in the size of the machine due to temperature changes, such as The difference is taken into account in further machining.

  It should be understood that it is advantageous to use the reference scanner or at least one coordinate direction twice for scanning. Here, the reference scanner is preferably used and switched once in its own longitudinal direction and once in its own transverse direction and switched. The scan pin pivot point is calculated from two grinding tests. This is important for subsequent processing of measurements.

The second part of the above-mentioned problem is solved by an apparatus characterized in that it comprises a device for carrying out the method of claim 1. The machine is equipped with a specimen and a mechanical scanner, where one of these elements is attached to the work spindle carrier and the other element is attached to the workpiece carrier. The machine is additionally provided with a control device, which has a corresponding control software. This control software performs the calibration process in one calibration manner with one reference scanner and performs the recalibration described in one recalibration manner with a corresponding mechanical scanner. This control software executes the steps described above. Here, this requires input data from the operator during the calibration process (initial calibration). In the simplest case, the input data is an estimated value for the size difference Δx. This is a result of the difference in size of the facets created in step 2. Machine adjustment specialists must supply appropriate estimates here. However, it is also possible to place the estimation module in the control software. This determines the correction value Δx (or Δy or Δz) from the facet size difference. Here, the estimation module is based on the assumption that a larger correction value Δx is assigned to a larger size difference between facets. In the simplest case, a proportional relationship is assumed and used as the basis.

  Additional details of advantageous embodiments of the invention are set forth in the drawings and description, and in the claims. 1 illustrates an embodiment of the present invention.

FIG. 1 very schematically shows a grinding machine or an electric discharge machine.

  FIG. 1 schematically shows a grinding machine 1. The grinding machine is provided with a machine table 2 that supports a grinding machine head 3 or a grinding spindle carrier and a workpiece carrier 4. The grinding machine head 3 is mounted in a corresponding sled-type arrangement and is movable in two directions Y and Z. Two corresponding drives are used to adjust the grinding machine head in these two directions. Here, the drive unit is connected to a control device 7 via a Y control line 5 and a Z control line 6. "Control line" here refers to any information conduit. That is, this is a data bus in which the control command is transferred to the corresponding drive unit and the position signal is returned from the drive unit to the control device 7.

  The workpiece carrier 4 is attached to the machine base 2 by a sled arrangement and is adjusted in the direction X. The X adjustment movement is controlled by the control device 7 via the X control line 8. Furthermore, the workpiece carrier may be pivotable about the vertical axis A. The turning motion is realized by a turning drive unit, and this turning drive unit is connected to the control device 7 via an A control line. The control device 7 is a control computer that accesses the memory device 11. For example, the memory device stores data and programs and keeps the data and programs available for access through the memory device 7.

The grinding machine head 3 is provided with a work spindle 12, and a grinding tool (that is, a grinding wheel) is attached to the work spindle for machining a workpiece. The rotation axis of the work spindle 12 is oriented parallel to the direction Y. Furthermore, a mechanical scanner 14 is arranged on the grinding machine head 3. Here, a scanner element 15 is provided in the mechanical scanner for scanning the test piece 16. The test piece is fixed to the workpiece carrier 4. The test piece 16 is, for example, a sphere fixedly attached to the workpiece carrier 4 and the scanner element 15 is a scanning pin having a scanning plate and / or a scanning ball. The workpiece carrier 4 is provided with a receiving portion 17 for a workpiece (that is, a cylindrical unprocessed part). this is. Perforator or other tool is generated in the grinding process from here.

The grinding machine 1 described so far is calibrated as follows:
A reference body in the form of a reference disk 18 is attached, for example, to the work spindle 12 of the grinding machine head 3, and a reference scanner 19 is attached to the workpiece receiving part 17 of the workpiece carrier 4, as shown in FIG. First calibration is performed. The reference scanner is designed as a switchable measuring scanner, for example. The scanning pin 21 rotates in the lateral direction and moves around the axis. In the case of a lateral displacement, this rotates about the turning point D as shown in FIG.

After the reference disk 18 and the reference scanner 19 are fixed to the grinder head 3 or the workpiece carrier 4, the control device moves the grinder head 3 in the Z direction and the rotation axis of the grinder head 3 is the center of the workpiece carrier 4. Moving in a calibration operation until it coincides with the longitudinal axis, the control device drives the workpiece carrier 4 towards the grinding machine head 3 in the direction X, and the reference disk 18 is moved by the reference scanner 19 as shown in FIG. Scanned. The work piece carrier 4 for is rotated about the axis A itself, the scanning pin 21 exists along the direction X. When the scanner reaches its switch point, the approaching movement of the workpiece carrier 4 stops. The position data of the workpiece carrier 4 obtained via the X control line 8 is calculated together with the known size data stored in the reference disk 18 and the reference scanner.

From the size and X position data of the reference scanner 19 and reference disk 18, the expected switch point that the reference scanner must respond to is obtained. Usually the actual switch point is different. The path difference Δx is stored.

As shown in FIG. 3, control devices assigned to axis A, so that the reference scanner 19 and the scanning pin 21 is parallel to exist with respect to the direction Y, through the A control line 9 Drive control. Thereafter, the scanning of the reference disk 18 in the X direction is performed again by driving and controlling the drive unit assigned in the X direction via the X control line 8. The Δx value is also determined through this test. Here, the position of the pivot point D of the scanning pin 21 in the reference scanner 19 is determined by comparing the results of the two tests described in FIGS.

  Then the test shown in FIG. 4 follows. Here, the axis Z oriented perpendicular to the drawing plane in FIG. 4 is used as the scanning direction. For this purpose, the drive device assigned to the direction Z is driven and controlled through the Z control line 6 as follows. That is, the reference scanner 19 is driven and controlled so as to respond thereto. Thereafter, a test for direction Y is performed according to FIG. As a result, corresponding values Δx, Δy are generated and stored.

  Immediately after performing such tests, a series of grinding tests are still performed within the first step frame for the initial calibration. These tests are illustrated in FIGS. In FIG. 6, the first grinding test in the X direction is based on the following facts. That is, the cylindrical unprocessed part or other part 22 clamped by the workpiece carrier 4 is oriented in the Y direction and approaches the grinding wheel 23 supported by the grinding machine head 3 in the X direction. Based on. Next, a feed movement leading to the grinding depth is performed in the X direction. A short push in the Y direction completes the grinding process. A second grinding test is performed on the same part 22 using the same grinding wheel 23 in accordance with FIG. Here, the workpiece carrier 4 is rotated 180 degrees around the axis A, and the part 22 is rotated 180 degrees around its longitudinal axis. Here, a second facet 25 is provided immediately adjacent to the facet 24. This is shown in FIG. 9 and is created in the first grinding test. The same grinding depth is achieved using existing machine adjustment data. However, this is generally not obtained in the first test. This is because the correction value Δx obtained by the reference process described above (as obtained according to FIGS. 2 and 3) is not yet accurate at first. FIG. 8 shows how the grinding wheel 23 actually penetrates the part 22 at different depths during the two grinding tests according to FIGS. 6 and 7. As a result, the facets 24, 25 are of different possible sizes even when there is almost no difference in grinding depth.

  The necessary correction of the correction value Δx is determined here from the difference in size between the facets 24 and 25. In the simplest case, this is performed by an operator and input to the control device 7 through an input element. However, it is also possible to measure only the size difference between the facets 24, 25. This means that the spread difference of the part 22 in the circumferential direction is measured and input to the control device 7. In this case, the control device 7 corrects the correction value Δx by a scale, which is proportional to the difference in the size of the facets 24, 25.

After performing this correction, the grinding test described in FIGS. 6 and 7 and the subsequent measurement of the facets 24 and 25 and the correction of the correction value Δx are repeated until the facets 24 and 25 are the same size. . Once this has been achieved, the additional correction value ΔxR, which is repeatedly determined in the grinding test, which is then added to the correction value Δx defined here, is regarded as the reference scanner correction value and the remaining coordinate directions Used in the same way for Y and Z. This is at least the case when the reference scanner 19 has the same switch point position in all displacement directions oriented transversely to the scan pin 21.

  The grinding tests shown in FIGS. 6-9 are used to refer to the scanning process of the reference scanner 19 shown in FIGS. 3-5, and FIGS. A grinding test process for referring to a reference scanner 19 during the process is shown. The test part 22 or other corresponding test part is used again, where its end face is ground. The test part 22 is guided from the positive and negative directions X towards the grinding wheel 23 and is ground at substantially the same depth. From the grinding diagram shown in FIG. 12 with different facets 26, 27, the X-error is again determined. This error represents a deviation ΔxA with respect to the axial direction of the reference scanner 19. The determination of the value ΔxA is completed when the facets 26, 27 obtained in repeated grinding tests have the same size.

  After reference to the grinding machine 1 and the reference scanner 19 carried out in this way, a first recalibration of the grinding machine 1 has to be carried out. Here, the mechanical scanner 14 is calibrated. This process is illustrated in FIGS. Recalibration is performed by scanning the specimen 16 with the mechanical scanner 14 or its scanner element 15. This is for example designed as a cube. As a result, the test piece 16 is scanned twice in the direction X as shown in FIGS. Here, the test piece is rotated 90 degrees about the A axis between two tests. After the first calibration is performed by the reference scanner 19 just before this, the switch position obtained here (where the mechanical scanner 14 responds) is stored and taken as the target value. Correspondingly, the specimen 15 is scanned in the Y direction in accordance with FIG. 15 and in the Z direction in accordance with FIG. The switch position obtained here is again stored as the target value.

  This completes the calibration of the grinding machine. This is operated based on the existing correction values Δx, Δy, Δz, ΔxR, ΔxA.

  For example, if the grinding machine is affected by a temperature change and then frequently needs to be recalibrated, the recalibration steps described in FIGS. 13-16 are repeated. In these four scanning tests, if there is a difference from the data stored during the initial calibration, the difference from the stored value is determined and stored again. These are taken into account in future positioning of the grinding machine head 3 or the workpiece carrier 4 as recalibration correction values.

  Recalibration is optionally repeated frequently and is performed by scanning the specimen 16 with a mechanical scanner 15 from different scan directions each time. No new calibration is necessary.

A new calibration or recalibration is performed in the same way on an EDM machine or a combined grinding / EDM machine.

Grinding and / or EDM machine calibration methods are premised on an initial calibration process and a corresponding recalibration process. Machine calibration is performed in an initial calibration process by a reference part and a reference scanner, where the reference part is fixed to the work spindle or workpiece carrier and the reference scanner is fixed to the work piece carrier or work spindle. The grinding test follows the first scanning process from all directions. During this test, deviations are determined which are inherent in the test process in an iterative manner, in particular based on scanner tolerances, and this effect is eliminated. After mechanical internal measurement system for treatment test directly, thus calibrated immediately after the first reference processing machine, wherein the machine scanner and the test piece is scanned from all coordinate directions, the position value arising as a result is stored. Subsequent recalibration will give a measurement. This is compared with the stored value, where from this deviation a correction value for further processing of the workpiece is determined.

Schematic of the various phases of the initial calibration process Schematic of the various phases of the initial calibration process Schematic of the various phases of the initial calibration process Schematic of the various phases of the initial calibration process Schematic of the various phases of the initial calibration process FIG. 2 is a schematic plan view of a grinder head with a grinding tool in contact with a green part during a grinding test at various positions. FIG. 2 is a schematic plan view of a grinder head with a grinding tool in contact with a green part during a grinding test at various positions. FIG. 8 is a schematic front view of the green part and the grinding tool shown in FIGS. 6 and 7. FIG. 4 is a schematic side view of a different scale of a green part with a slightly ground part. FIG. 2 is a schematic plan view of a grinder head with grinding tools and raw parts at different grinding positions during the grinding process. FIG. 2 is a schematic plan view of a grinder head with grinding tools and raw parts at different grinding positions during the grinding process. FIG. 12 is a schematic front view of the green part after performing the grinding process shown in FIGS. 10 and 11. The figure showing the recalibration step. The figure showing the recalibration step. The figure showing the recalibration step. The figure showing the recalibration step.

Claims (11)

A method for calibrating a machine for grinding and / or electrical discharge machining with a work spindle (12), a mechanical scanner (14) and a workpiece carrier (4),
The work spindle (12) is configured to receive a grinding tool or an electric discharge machining tool (23),
The mechanical scanner (14) is connected to a work spindle carrier or grinder head (3),
The workpiece carrier (4) for the workpiece has a workpiece receiving element (17),
The relative position of the workpiece spindle carrier or grinding machine head (3) and the workpiece carrier (4) can be adjusted by a control device under the control of a control unit (7);
The control unit (7) is provided with a memory unit (11),
The mechanical scanner (14) is fixed to the work spindle carrier or grinder head (3), and a test piece (16) is fixed to the workpiece carrier (4);
In a first step, a reference body (18) is attached to the work spindle (12), a reference scanner (19) is attached to the workpiece receiving element (17),
Scanning the reference body (18) by bringing the reference scanner (19) into contact with the reference body (18), and storing the measured values of the coordinates of the contact point in the memory unit (11),
A correction value (Δx, Δy, Δz) obtained from the difference between the target value for the contact point and the measured value is stored in the memory unit (11),
In a second step, a grinding tool (23) is attached to the work spindle (12), an object (22) is attached to the workpiece receiving element (17),
Grinding the object (22) from different directions in the grinding test using the correction values (Δx, Δy, Δz) in the memory unit (11),
In the third step, the estimated correction value obtained from the difference in size in the circumferential direction of the object (22) of the plurality of ground portions (24, 25, 26, 27) created in the second step. Is added to the measured values (Δx, Δy, Δz) stored during the first step ,
In the fourth step, the test piece (16) is contacted and scanned with the mechanical scanner (14) using the correction values (Δx, Δy, Δz) of the memory unit (11), and the contact is performed. A difference (Δxn, Δyn, Δzn) between a target value related to a point and the measured value is obtained, and a correction value (Δx, Δy, Δz) in the memory unit (11) based on the difference (Δxn, Δyn, Δzn). And / or adjusting the measured value,
A method for calibrating a machine. During the adjustment in the fourth step, a correction value (Δx, Δy, Δz) is obtained as a difference between the actual machine coordinates (X, Y, Z, A) and the measured value obtained in the steps 1 to 3. )
The method according to claim 1, wherein the correction values (Δx, Δy, Δz) are taken into account in the subsequent part machining of the part.   The method according to claim 1, wherein the fourth step is repeated to adjust the measurement value.   2. The method according to claim 1, wherein a reference disk is used as the reference body (18).   The method according to claim 1, wherein a switch probe is used as the reference scanner (19).   The reference body (18) is scanned once from all coordinate directions (X, Y, Z), respectively, and twice from the selected coordinate direction (X) in different scanner orientations. Method.   The method according to claim 1, wherein the object (22) is ground in a second step from the forward and reverse directions of the coordinates in order to check the accuracy of the coordinates.   The method according to claim 7, wherein the object (22) is ground in two adjacent parts (24, 25, 26, 27).   The method according to claim 8, wherein the correction value estimated in the third step is determined from a difference in size of the adjacent portion (24, 25, 26, 27) in the circumferential direction of the object (22).   In the third step, when the estimated correction value exceeds an allowable value, the estimated correction value is transmitted to the control unit (7) to correct the stored measurement value. The method described. An apparatus for grinding and / or electrical discharge machining having a work spindle (12), a mechanical scanner (14) and a workpiece carrier (4),
The work spindle is configured to accept a grinding tool or an electric discharge machining tool (23),
The mechanical scanner (14) is connected to a work spindle carrier or grinder head (3),
The workpiece carrier (4) for the workpiece has a workpiece receiving element (17),
The relative position of the workpiece spindle carrier or grinding machine head (3) and the workpiece carrier (4) can be adjusted by a control device under the control of a control unit (7);
The control unit (7) is provided with a memory unit (11),
The mechanical scanner (14) is fixed to the work spindle carrier or grinder head (3), and a test piece (16) is fixed to the workpiece carrier (4);
The control unit (7)
(A) A reference body (18) is attached to the work spindle (12) and a reference scanner (19) is attached to the workpiece receiving element (17). The reference scanner (19) is contacted and scanned, and a measurement value for the coordinates of the contact point is obtained.
A correction value (Δx, Δy, Δz) obtained from the difference between the target value for the contact point and the measured value is stored in the memory unit (11),
(B) Correction value of the memory unit (11) with the grinding tool (23) attached to the work spindle (12) and the object (22) attached to the workpiece receiving element (17). Grinding the object (22) from different directions using (Δx, Δy, Δz),
(C) An estimated correction value obtained from a difference in size of the created grinding portions (24, 25, 26, 27) in the circumferential direction of the object (22) is calculated during the first step. It was added to the measured values stored in,
(D) Using the correction values (Δx, Δy, Δz) in the memory unit (11), the mechanical scanner (14) is brought into contact with the test piece (16) for scanning, and the contact point is obtained. The difference (Δxn, Δyn, Δzn) between the target value and the measured value is obtained,
Based on the difference (Δxn, Δyn, zn) indicating the difference of the mechanical scanner (14) with respect to the reference scanner (19), correction values (Δx, Δy, Δz) in the memory unit (11) and / or Or adjust the measured value,
Do control,
A device characterized by that.

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