Jig for setting up a standard, and method for measuring a standard in a machine tool

Abstract

To make it possible to easily install a reference unit, which is used for measuring motion error of a machine tool, in a prescribed direction on a table.SOLUTION: A jig 20 for installation of a reference unit installs a reference unit in a prescribed direction on a table when the reference unit installed in the prescribed direction on the table is measured by use of a sensor attached to the spindle head, in a machine tool which has 2 or more translational axes, the table provided with a plurality of grooves, and the spindle head capable of holding a tool and in which the tool held by the spindle head is capable of performing relative motion with two or more translational degrees of freedom by the translational axes for a work-piece installed on the table. The jig includes: a plate 21 provided with a plurality of holes 22; and a plurality of bar stocks 23 which can be inserted in the holes 22. The plurality of bar stocks 23, which are each inserted in any multiple holes 22, are inserted in any grooves provided on the table of the machine tool, so that any side face 21a of the plate 21 becomes parallel to the prescribed direction on the table.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a standard installation jig for installing a standard used to measure the motion error of a machine tool in a predetermined direction on a table, and a method for measuring the standard in a machine tool. [Background technology]

[0002] FIG. 1 is a schematic diagram of a machine tool M having three translational axes. The spindle head 2 is capable of translational movement with two degrees of freedom along the X and Y axes, which are translational axes that are perpendicular to each other. The spindle head 2 is also capable of translational movement with one degree of freedom along the Z axis, which is perpendicular to the X and Y axes. Therefore, the spindle head 2 has three degrees of freedom of translation relative to the table 3 on the bed 1. Each axis is driven by a servo motor controlled by a numerical control device. The workpiece W is fixed to the table 3, and a tool is attached to the spindle of the spindle head 2 and rotated to machine the workpiece W into any shape. Machine tools have motion errors such as positioning errors, straightness errors, and squareness errors. These motion errors affect the machining accuracy and measurement accuracy of workpieces. To measure the motion errors of machine tools, a standard 12, which serves as the accuracy standard, is installed on table 3 facing in a specified direction, as shown in Figure 2, and the relative positions of target balls (P1 to P5) attached to standard 12 are measured using a touch probe 11 or displacement sensor attached to spindle head 2. In this case, the installation direction of standard 12 is measured using touch probe 11, and the ideal position of the target ball on standard 12 is calculated based on the results. The ideal position and the measured position of the target ball are then compared to measure the motion errors of the machine tool.

[0003] Patent Document 1 discloses a method for measuring the motion error of a machine tool by using a gauge (standard) with multiple spheres fixed to it to measure the distance between the spheres of the gauge and evaluate the error. This gauge has a base and an arm attached to the base and carrying multiple spheres, and the arm can rotate horizontally and / or vertically by any angle. Furthermore, Non-Patent Document 1 discloses a machine vise that places a workpiece on a table in a predetermined orientation. A guide block is provided on the bottom surface of this machine vise, and the machine vise can be placed in a predetermined orientation by fitting the guide block into a groove in the table. Therefore, it is conceivable to provide a guide block on the bottom surface of a datum and similarly use the groove in the table to place the datum. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6960893 [Non-patent literature]

[0005] [Non-Patent Document 1] "Machine Vise" Nabeya Co., Ltd. [Retrieved April 28, 2022], Internet<URL:https: / / www.nabeya.co.jp / search.php?grp=J> Summary of the Invention [Problem to be solved by the invention]

[0006] The gauge in Patent Document 1 has a complex mechanism, which not only increases the manufacturing cost but also makes it inconvenient to set on a table or carry around due to its weight. On the other hand, when using the guide block disclosed in Non-Patent Document 1, a tapped hole and guide groove are required on the bottom surface of the reference device to attach the guide block in a predetermined direction, which requires additional processing on the existing product. However, additional processing may change the accuracy of the reference device. Also, it cannot be used if the table does not have a groove.

[0007] Therefore, the present disclosure aims to provide a standard installation jig that allows a standard used to measure the motion error of a machine tool to be easily installed in a specified direction on a table, and a method for measuring a standard in a machine tool. [Means for solving the problem]

[0008] In order to achieve the above object, a first configuration of the present disclosure provides a machine tool having two or more translational axes, a table with a plurality of grooves or tapped holes, and a spindle head capable of holding a tool, wherein the tool held by the spindle head is capable of relative translational movement with two or more degrees of freedom relative to a workpiece placed on the table by the translational axes, the machine tool comprising: a reference device installation jig for installing a reference device in a predetermined direction on the table when measuring the reference device placed in a predetermined direction on the table using a sensor attached to the spindle head, the jig comprising: 3 or more a plate having a hole; a plurality of rods insertable into the holes; so that an angle formed by a first line connecting any two of the holes and a side surface of the plate that is a reference for the predetermined direction, or an angle formed by the first line and a second line connecting two holes different from either one or both of the two holes, is equal to an angle formed by a line in the direction in which the grooves of the table extend or a line connecting two of the tapped holes, and the predetermined direction, The plurality of rods inserted into the plurality of holes are then arbitrarily 1 bottle The groove or Any By inserting the tapped hole, the plate The above criteria The side surface or the straight line connecting the plurality of rods is parallel to the predetermined direction. The plate can be positioned so that The reference device can be installed in the predetermined direction by directly contacting the reference side surface of the plate positioned on the table or the plurality of rods, or by contacting the reference device indirectly via another auxiliary jig. It is characterized by: In order to achieve the above object, a second configuration of the present disclosure is a machine tool having two or more translational axes, a table with a plurality of grooves or tapped holes, and a spindle head capable of holding a tool, wherein the tool held by the spindle head can move relative to a workpiece placed on the table with two or more degrees of translational freedom by the translational axes, the method comprising: installing a reference device in a predetermined direction on the table; and measuring the reference device using a sensor attached to the spindle head, On the table, the reference device installation jig according to the first configuration is placed, The aforementioned Plate The above criteriaPositioning the side surface or the straight line connecting the plurality of rods in the predetermined direction; The reference device, The above criteria The rod is placed in the predetermined direction by directly contacting the side surface or the plurality of rods or indirectly contacting the side surface or the plurality of rods via other auxiliary jigs, The sensor is used to measure the reference device. [Effects of the Invention]

[0009] According to the present disclosure, a lightweight and inexpensive standard installation jig can be provided that allows a standard to be easily installed in a predetermined direction when measuring the motion error of a machine tool. Furthermore, since there is no need to attach parts to the standard, it can also be used for pre-made standard devices. Furthermore, even if there is no groove on the table, the standard can be installed in a predetermined direction using tapped holes for measurement. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a machine tool having X-, Y-, and Z-axis translation axes. [Figure 2] FIG. 1 is a schematic diagram of a touch probe and a reference device installed on a table. [Figure 3] 1 is an example of a reference device installation jig of form 1. [Figure 4] 10 is another example of the reference device installation jig of form 1. [Figure 5] FIG. 10 is a schematic diagram showing a standard installed in a direction along the groove of a table using the standard installation jig of the first embodiment. [Figure 6] FIG. 10 is a schematic diagram showing a standard installed in a direction perpendicular to the groove of a table using the standard installation jig of the first embodiment. [Figure 7] FIG. 10 is a schematic diagram showing a standard installed at 45° to the groove of the table using the standard installation jig of the first embodiment. [Figure 8] 10 is another example of the reference device installation jig of form 2. [Figure 9]FIG. 10 is a schematic diagram showing a standard installed in a direction perpendicular to the groove of the table using the standard installation jig and auxiliary jig of form 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. [Form 1] First, an example of a standard installation jig according to the first configuration will be described. As shown in FIG. 3, standard installation jig (hereinafter simply referred to as "jig") 20 is composed of a plate 21 having a square shape in plan view, with four holes 22, 22, . . . formed through each corner, and two rods 23, 23. In jig 20, the angle formed between each side surface of plate 21 and a line connecting two of the four holes 22, 22 is either 0°, 45°, or 90°. The rods 23 can be inserted into holes 22. Note that holes 22 are not limited to through holes, but may also be blind holes or tapped holes, as long as they can accommodate the insertion of the rods. Furthermore, plate 21 is not limited to a square, but may also be a triangle or a polygon with five or more corners, as shown in FIG. 4.

[0012] Here, measurements are performed by placing reference device 12 in the X-axis direction, which is a predetermined direction, Y-axis direction, and a direction at an angle of 45° to the X-axis. Below, a method according to a second configuration in which reference device 12 is placed in a predetermined direction using jig 20 and measurements are performed will be described with reference to Figures 5 to 7. 5 shows a state in which a reference device 12 having a plurality of target spheres P1, P2, etc., equally spaced on its upper surface is installed in the X-axis direction using a jig 20. A plurality of grooves 4 (only one is shown in FIG. 5) are provided in the upper surface of a table 3 of a machine tool M in the X-axis direction. In this example, first, two rods 23 are inserted into two holes 22 provided in the plate 21. In FIG. 5, the holes 22 are through holes, but if the holes 22 are blind holes or tapped holes, the rods 23 are inserted from the underside of the plate 21. The holes 22 used in this case are two that are aligned in a direction parallel to the pair of parallel side surfaces 21a of the plate 21. Next, the rods 23, 23 protruding downward from the plate 21 are inserted into the groove 4. Then, the plate 21 is positioned so that the side surface 21a is parallel to the groove 4. Therefore, by pressing the longitudinal side surface of the datum 12 against one of the side surfaces 21a of the installed plate 21, the datum 12 can be installed in the X-axis direction.

[0013] In the jig 20, the angle (here 0°) formed by the first straight line L1 connecting the two holes 22, 22 and the side surface 21a of the plate 21 is equal to the angle (here 0°) formed by the straight line L in the direction of the groove 4 of the table 3 and the predetermined direction, the X-axis direction. Therefore, when the rods 23, 23 inserted into the holes 22, 22 are inserted into the groove 4, the side surface 21a parallel to it becomes parallel to the X-axis direction. Therefore, the reference device 12 pressed against the side surface 21a is also placed in the X-axis direction.

[0014] Next, a description will be given of a method for measuring the positions of two target spheres P1 and P2 on the installed reference device 12 using the touch probe 11. The touch probe 11 is an example of a sensor of the present disclosure. The reference device 12 is installed approximately in the X-axis direction, and the relative X-, Y-, and Z-axis positions of the target spheres P1 and P2 are known. Therefore, the target spheres P1 and P2 can be measured automatically using the touch probe 11. Note that the positions of the target spheres P1 and P2 only need to be within the range that can be measured by the touch probe 11, and the position and inclination at which the jig 20 is installed, as well as the dimensions and geometric accuracy of the jig 20, do not need to be highly accurate. Measurement values ​​Xm2, Ym2, Zm2 of the relative positions of the target spheres P1 and P2 can be obtained by measuring the positions of the target spheres P1 and P2 using the touch probe 11. If the relative positions of the target spheres P1 and P2 in the X, Y, and Z directions when the reference device 12 is installed in the X-axis direction are Xc2, Yc2, and Zc2, the error values ​​δx2, δy2, and δz2 can be calculated using the following equations. δx2=Xm2-Xc2 δy2=Ym2-Yc2 δz2=Zm2-Zc2

[0015] The tilt errors ay and az in the Y and Z directions of the installation direction are calculated as follows. ay=δy2 / Xc2 az=δz2 / Xc2

[0016] By taking into consideration the tilt errors ay and az of the reference device 12, the relative positions Xci', Yci', and Zci' of the target sphere Pi (i=3 to 5) with respect to P1 are calculated as follows. Xci'=Xci Yci'=Yci+ay*Xci Zci'=Zci+az*Xci Here, Xci, Yci, and Zci are the relative positions of the target sphere Pi (i=3 to 5) with respect to P1 before the tilt error is corrected. Each target sphere Pi can be measured by determining the command value for each axis based on the relative positions Xci', Yci', Zci' that have been corrected for the obtained tilt error. In addition, the motion error can be measured by comparing the command value for each axis with the measured value.

[0017] 6 shows the state in which the datum 12 is installed in the Y-axis direction using a jig 20. As with the installation in the X-axis direction, two rods 23 are inserted into two holes 22 provided in a plate 21. The holes 22 are aligned in a direction perpendicular to the side surface 21a of the plate 21. Next, by inserting the inserted rods 23, 23 into the groove 4, the plate 21 can be positioned so that the side surface 21a is perpendicular to the groove 4. Therefore, by pressing the longitudinal side surface of the datum 12 against one of the side surfaces 21a of the positioned plate 21, the datum 12 can be installed in the Y-axis direction. In the jig 20, the angle (here 90°) between the first straight line L1 connecting the two holes 22, 22 and the side surface 21a of the plate 21 is equal to the angle (here 90°) between the straight line L in the direction in which the groove 4 of the table 3 extends and the Y-axis direction, which is a predetermined direction. Therefore, when the rods 23, 23 inserted into the holes 22, 22 aligned in the direction of the first straight line L1 are inserted into the groove 4, the side surface 21a perpendicular to the rods 23, 23 becomes parallel to the Y-axis direction. Therefore, the reference device 12 pressed against the side surface 21a is also placed in the Y-axis direction. The motion error can be measured by correcting the position of the target ball by the amount of tilt error, in the same way as when the installed reference device 12 was installed in the X-axis direction.

[0018] 7 shows a state in which the reference device 12 is installed at a 45° angle with respect to the X-axis using a jig 20. First, two rods 23 are inserted into two holes 22 provided in a plate 21. The holes 22 used in this case are aligned in a 45° direction (diagonal direction) with respect to a side surface 21a of the plate 21. Next, by inserting the inserted rods 23, 23 into the groove 4, the plate 21 can be positioned so that the side surface 21a is oriented at 45° with respect to the groove 4. Therefore, by pressing the longitudinal side surface of the datum 12 against one of the side surfaces 21a of the positioned plate 21, the datum 12 can be installed at 45° with respect to the X-axis. In the jig 20, the angle (here 45°) formed by the first straight line L1 connecting the two holes 22, 22 and the side surface 21a of the plate 21 is equal to the angle (here 45°) formed by the straight line L in the direction of the groove 4 of the table 3 and the 45° direction relative to the X-axis, which is a predetermined direction. Therefore, when the rods 23, 23 inserted into the holes 22, 22 aligned in the direction of the first straight line L1 are inserted into the groove 4, the side surface 21 a becomes parallel to the 45° direction with respect to the X axis. Therefore, the reference device 12 pressed against the side surface 21 a is also set in the 45° direction with respect to the X axis. The motion error can be measured by correcting the position of the target ball by the amount of tilt error, in the same way as when the installed reference device 12 was installed in the X-axis direction.

[0019] The jig 20 of the above-mentioned form 1 includes a plate 21 having a plurality of holes 22 and a plurality of rods 23 that can be inserted into the holes 22, and by inserting the plurality of rods 23 inserted into any of the plurality of holes 22 into any of the grooves 4, any of the side surfaces 21a of the plate 21 on the table 3 become parallel to a predetermined direction. Furthermore, the method for measuring the standard device 12 in the above-mentioned form 1 is to position the jig 20 on the table 3 so that any side surface 21a of the plate 21 is in a predetermined direction, and the standard device 12 is placed in the predetermined direction by directly abutting it against the side surface 21a of the plate 21, and then measure the standard device 12 using the touch probe 11. According to this configuration, the reference unit 12 used to measure the motion error of the machine tool can be easily installed in a predetermined direction on the table 3. Furthermore, since there is no need to attach parts to the reference unit 12, the configuration is lightweight and inexpensive, and it can also be used for ready-made reference units 12.

[0020] [Form 2] In the above-mentioned embodiment 1, the reference device 12 is installed by directly abutting it against the jig 20, but it is also possible to use another jig and install the reference device 12 indirectly by the jig 20. This embodiment will be explained below. Note that the same components as those in embodiment 1 are assigned the same reference numerals and redundant explanations will be omitted. As shown in Fig. 8, the jig 20 is composed of a plate 21 having four holes 22, 22... and three rods 23, 23.... In the jig 20, the angle formed by the line connecting two reference holes 22, 22 and the line connecting one of the same holes 22 with another hole 22 or the line connecting two other holes 22, 22 is 0°, 45°, or 90°. Each rod 23 can be inserted into each hole 22. FIG. 9 shows the state in which the datum 12 is installed in the Y-axis direction via another jig, an auxiliary jig 13. First, two rods 23, 23 (labeled "23A" to distinguish them) are inserted through two holes 22, 22 (labeled "22A" to distinguish them) aligned parallel to the side surface 21a of the plate 21. Next, the inserted rods 23A, 23A are inserted into the groove 4. Finally, a rod 23 (labeled "23B" to distinguish it) is inserted from above into a hole 22 (labeled "22B" to distinguish it) aligned perpendicular to the groove 4, and the auxiliary jig 13 is pressed against the two rods 23A, 23B aligned vertically. This allows the datum 12, fixed parallel to the auxiliary jig 13, to be installed perpendicular to the groove 4.

[0021] The auxiliary jig 13 is in the shape of a strip having a lower portion 13a that is thicker than the plate 21 and an upper portion 13b that is wider than the lower portion 13a, and the datum 12 can be positioned parallel to the upper surface of the upper portion 13b. This positioning can be easily achieved by forming a groove in the longitudinal direction on the upper surface of the upper portion 13b, into which the datum 12 fits. When the longitudinal side surface of the upper stage portion 13b, which has positioned the standard 12 in this way, is brought into contact with the rods 23A and 23B aligned in the Y-axis direction, the auxiliary jig 13 is fixed in the Y-axis direction. Therefore, the standard 12 on the auxiliary jig 13 is also set in the Y-axis direction. In the jig 20, the angle (here 90°) formed by the first straight line L1 connecting the two holes 22A, 22A and the second straight line L2 connecting the two holes 22A, 22A and two holes 22A, 22B, one of which is different, is equal to the angle (here 90°) formed by the straight line L in the groove direction of the table 3 and the Y-axis direction. Therefore, when the bars 23A, 23A inserted into the holes 22A, 22A aligned in the direction of the first straight line L1 are inserted into the groove 4, the bars 23A, 23B aligned in the direction of the second straight line L2 become parallel to the Y-axis direction. Therefore, the auxiliary jig 13 pressed against the bars 23A, 23B aligned in the direction of the second straight line L2 is also set in the Y-axis direction. Subsequently, in the same manner as in the first embodiment, the position of the target sphere of the installed reference device 12 is measured by the touch probe 11, thereby making it possible to measure the motion error.

[0022] The jig 20 of the above-mentioned form 2 also includes a plate 21 having a plurality of holes 22A, 22B and a plurality of rods 23A, 23B that can be inserted into the holes 22A, 22B, and by inserting the plurality of rods 23A, 23A inserted into any of the plurality of holes 22A, 22A, respectively, into any of the grooves 4, a second straight line L2 connecting the rods 23A, 23B on the table 3 becomes parallel to a predetermined direction. Furthermore, the method of measuring the standard device 12 in the above-mentioned form 2 is to position the jig 20 on the table 3 so that the second straight line L2 connecting the rods 23A and 23B is in a predetermined direction, and then the standard device 12 is placed in a predetermined direction by indirectly abutting it against the rods 23A and 23B via the auxiliary jig 13, and the standard device 12 is measured using the touch probe 11. According to this configuration, the reference unit 12 used to measure the motion error of the machine tool can be easily installed in a predetermined direction on the table 3. Furthermore, since there is no need to attach parts to the reference unit 12, the configuration is lightweight and inexpensive, and it can also be used for ready-made reference units. The auxiliary jig is not limited to the above-described form, and may be in contact with the side surface of a plate instead of a rod. The joining structure with the jig can also be changed as appropriate.

[0023] Below, examples of modifications common to each embodiment will be described. The rod of the jig is inserted into a groove on the table, but if the table has multiple tapped holes instead of grooves, the jig can be positioned by inserting or screwing the rod into the tapped holes. By using tapped holes in this way, it is possible to install a standard in a specified direction and perform measurements even if the table does not have a groove. The number and positions of holes (including blind holes and tapped holes) in the plate are not limited to the above-mentioned embodiments and can be changed as appropriate. The shape of the holes is also not limited to circles, and other shapes such as squares and polygons can be used. The shape of the rod can also be changed as appropriate to match the shape of the holes. The structure of the standard itself is not limited to the above. The number of target balls can be increased or decreased, and their placement can be changed. Standards having measurement targets other than target balls can also be used. Sensors other than touch probes can also be used, such as displacement sensors. [Explanation of symbols]

[0024] 1··Bed, 2··Spindle head, 3··Table, 4··Groove, 11··Touch probe, 12··Diameter, 13··Auxiliary jig, 20··Diameter installation jig, 21··Plate, 21a··Side, 22··Hole, 23··Bar stock, M··Machine tool, W··Workpiece.

Claims

1. In a machine tool having two or more translational axes, a table with a plurality of grooves or tapped holes, and a spindle head capable of holding a tool, wherein the tool held by the spindle head is capable of translational movement with two or more degrees of freedom relative to a workpiece placed on the table by the translational axes, a standard setting jig for setting a standard in a predetermined direction on the table when measuring the standard set in a predetermined direction on the table using a sensor attached to the spindle head, comprising: a plate having three or more holes; a plurality of rods insertable into the holes; the plurality of rods inserted into the plurality of holes are inserted into any one of the grooves or any of the tapped holes so that the angle formed by a first line connecting any two of the holes and the side surface of the plate serving as a reference for the predetermined direction, or the angle formed by the first line and a second line connecting two holes different from either or both of the two holes, is equal to the angle formed by a line in the direction in which the grooves of the table extend or a line connecting two of the tapped holes and the predetermined direction, thereby positioning the plate on the table so that the side surface serving as a reference of the plate or the line connecting the plurality of rods is parallel to the predetermined direction, A standard installation jig characterized in that the standard can be installed in the specified direction by directly abutting the standard against the reference side of the plate positioned on the table or against the multiple rods, or by abutting the standard indirectly via another auxiliary jig.

2. In a machine tool having two or more translational axes, a table with a plurality of grooves or tapped holes, and a spindle head capable of holding a tool, wherein the tool held by the spindle head can move relative to a workpiece placed on the table with two or more degrees of translational freedom by the translational axes, a reference device is placed in a predetermined direction on the table, and a method for measuring the reference device using a sensor attached to the spindle head is provided, The reference device installation jig according to claim 1 is positioned on the table so that the reference side surface of the plate or the straight line connecting the plurality of rods is in the predetermined direction; The reference device is placed in the predetermined direction by directly contacting the reference side surface or the plurality of rods or indirectly contacting the reference side surface or the plurality of rods via another auxiliary jig, A method for measuring a standard in a machine tool, comprising measuring the standard using the sensor.

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