JP5769456B2 - Thermal displacement correction apparatus and thermal displacement correction method - Google Patents

Description

  The present invention relates to a thermal displacement correction device and a thermal displacement correction method for correcting a thermal displacement of a workpiece in a machine tool.

  Japanese Patent Laying-Open No. 2006-281335 (Patent Document 1) describes a thermal displacement correction method for correcting thermal displacement of a workpiece. This document describes that the cutting edge position of the tool is corrected in consideration of the thermal displacement amount of the workpiece.

JP 2006-281335 A

  Here, the present inventors consider that the linear expansion coefficient of the workpiece is a theoretical value and that it extends in a linear direction connecting the direction of thermal displacement with the reference point, and the thermal displacement amount of the workpiece is calculated using the theoretical value. did. However, when comparing the actual measured thermal displacement value and the theoretical thermal displacement amount, we found that there was a shift between the two.

  This invention is made | formed in view of such a situation, and it aims at providing the thermal displacement correction apparatus and the thermal displacement correction method which can correct | amend the thermal displacement of workpiece | work itself with higher precision.

(Thermal displacement correction device)
As a result of intensive studies, the present inventors have found that the direction of thermal displacement and the magnitude of thermal displacement differ from theoretical values due to the influence of the shape of the workpiece. Specifically, it has been found that the thermal displacement direction of a predetermined point viewed from the reference point is deviated from a straight line connecting the reference point and the predetermined point.

  (Claim 1) Accordingly, a thermal displacement correction device according to the present invention is a thermal displacement correction device that corrects the relative position of a tool with respect to a reference point of the workpiece based on the thermal displacement of the workpiece, and the temperature of the workpiece is adjusted. A database that stores a thermal displacement direction of a predetermined point of the workpiece with respect to a reference point of the workpiece measured in advance when actually changed, a temperature measuring unit that directly or indirectly measures the temperature of the workpiece at the time of machining, Based on the thermal displacement direction of the predetermined point of the workpiece stored in the database, the temperature of the workpiece measured by the temperature measuring means, and the linear expansion coefficient of the workpiece, the predetermined point of the workpiece at the time of machining Based on the thermal displacement correction position when processing a predetermined point of the workpiece with the tool, a thermal displacement correction position calculating means for calculating a thermal displacement correction position And a correcting means for correcting the relative position of the tool relative to the reference point of the workpiece.

  (Claim 2) Further, the database is calculated based on a thermal displacement amount of a predetermined point of the workpiece with respect to a reference point of the workpiece measured in advance when the temperature of the workpiece is actually changed, and the temperature of the workpiece. The thermal expansion correction position calculation means calculates a thermal displacement correction position at a predetermined point of the workpiece using the linear expansion coefficient of the workpiece stored in the database. You may make it do.

  (Claim 3) Further, there may be a plurality of predetermined points of the workpiece, and the linear expansion coefficient stored in the database may be an average value of linear expansion coefficients at a plurality of predetermined points of the workpiece. .

  (Claim 4) In addition, the machining part of the workpiece is a plurality of holes, the predetermined points of the workpiece are the holes, and the linear expansion coefficient stored in the database is A linear expansion coefficient of each predetermined point, and the thermal displacement correction position calculating means uses the linear expansion coefficient of each predetermined point of the workpiece stored in the database to calculate the predetermined point of each of the workpieces. The thermal displacement correction position may be calculated.

(Claim 5) Further, the processing part of the workpiece is a curved surface part or a planar shape part, and the predetermined points of the workpiece are a plurality of points included in the processing part of the workpiece, and are stored in the database. and the thermal displacement direction, said the thermal displacement direction of the respective predetermined points of the work, the thermal displacement correction position calculating means, the thermal displacement direction depending on the machining point of the workpiece, is stored in the database It may be calculated by interpolation using the thermal displacement direction of each predetermined point of the workpiece.

(Thermal displacement correction method)
In the above description, the present invention is described as a thermal displacement correction device. In addition, the present invention can also be regarded as a thermal displacement correction method.

  (Claim 6) A thermal displacement correction method according to the present invention is a thermal displacement correction method for correcting a relative position of a tool with respect to a reference point of the workpiece on the basis of the thermal displacement of the workpiece, wherein the temperature of the workpiece is actually set. A measuring step for measuring in advance a thermal displacement direction of a predetermined point of the workpiece with respect to a reference point of the workpiece when changed, a temperature measuring step for directly or indirectly measuring the temperature of the workpiece during processing, and the previously measured Based on the thermal displacement direction at a predetermined point of the workpiece, the temperature of the workpiece measured in the temperature measuring step, and the linear expansion coefficient of the workpiece, the thermal displacement correction position at the predetermined point of the workpiece at the time of machining is calculated. A thermal displacement correction position calculating step, and a relative position of the tool with respect to a reference point of the workpiece based on the thermal displacement correction position when the predetermined point of the workpiece is machined by the tool. And a correcting step of correcting the location. In addition, the characteristic part about the thermal displacement correction | amendment apparatus which concerns on this invention mentioned above is applicable similarly also to the said thermal displacement correction method.

  (Claim 1) According to the present invention, the thermal displacement direction of a predetermined point of the workpiece with respect to the reference point of the workpiece is obtained by actually performing an experiment and measuring. That is, the thermal displacement direction as an actual measurement value is stored in the database. And the thermal displacement correction position according to the temperature of the workpiece | work at the time of a process is calculated using the thermal displacement direction as a measured value memorize | stored in this database. Here, the thermal displacement position means the coordinates at which the predetermined point of the workpiece has moved as the workpiece temperature has changed from the reference temperature with the predetermined point of the workpiece when the workpiece temperature is the reference temperature as the origin. To do.

  Therefore, according to the present invention, the thermal displacement correction position for performing the thermal displacement correction can be matched with the actual thermal displacement position with high accuracy. As a result, processing accuracy can be improved. Here, as a means for directly measuring the temperature of the workpiece, a contact-type or non-contact-type temperature sensor can be used for the workpiece. As means for indirectly measuring the workpiece temperature, there are means for estimating the coolant temperature supplied to the workpiece machining point as the workpiece temperature, and means for estimating the room temperature as the workpiece temperature.

  (Claim 2) The present inventors have found that not only the thermal displacement direction but also the linear expansion coefficient differs for each part of the workpiece due to the influence of the shape of the workpiece. Therefore, in the present invention, an experiment was actually performed to measure the linear expansion coefficient at each predetermined point. Then, the amount of thermal displacement was calculated using the workpiece temperature during processing and the linear expansion coefficient measured by experiment. Therefore, the thermal displacement amount at each predetermined point can be matched with the actual thermal displacement amount with high accuracy. That is, the thermal displacement direction and the thermal displacement amount at each predetermined point can be matched with the actual thermal displacement direction and the thermal displacement amount with high accuracy. As a result, the thermal displacement correction position at each predetermined point can be matched with the actual thermal displacement position with higher accuracy.

  (Claim 3) As in the present invention, by using the average value of the values measured by experiments as the linear expansion coefficient used for calculating the thermal displacement, the linear expansion coefficient is used as the linear expansion coefficient of the actual workpiece. It can be approximated. As a result, the thermal displacement amount at each predetermined point can be matched with the actual thermal displacement amount with high accuracy. Furthermore, by using a constant value for a plurality of predetermined points as the linear expansion coefficient, the calculation processing speed of the thermal displacement amount can be increased. Thereby, since high followability to a processing position can be secured, processing accuracy can be improved.

  (Claim 4) According to the present invention, the respective linear expansion coefficients are stored in the database for a plurality of holes as processing parts. Therefore, the amount of thermal displacement at each predetermined point is calculated using the linear expansion coefficient corresponding to each predetermined point. As a result, the amount of thermal displacement at each predetermined point can be surely matched with the actual amount of thermal displacement.

  (Claim 5) When machining a curved surface portion or a planar shape portion, it is possible to calculate the thermal displacement amount at predetermined scattered points with high accuracy and to interpolate the thermal displacement amount between the predetermined points. Can be calculated with high accuracy. Therefore, even when a curved surface portion or a planar shape portion is processed, correction according to the actual thermal displacement amount of each portion can be performed. As a result, highly accurate processing can be realized.

  (Claim 6) In the thermal displacement correction method of the present invention, the same effects as those of the thermal displacement correction apparatus of the present invention described above can be obtained. In addition, when the above-described characteristic portions of the thermal displacement correction device are applied to the thermal displacement correction method, the same effects can be achieved by the respective features.

1 is a side view of a machine tool. It is a perspective view of a workpiece. It is a top view of a workpiece | work. It is a flowchart regarding the procedure of thermal displacement correction | amendment. It is an enlarged view shown about the center position Oa5 of the hole P5 thermally displaced when measuring in advance. It is a control block configuration of a machine tool. It is a table | surface which shows the information memorize | stored in a database. It is an enlarged view which shows the thermal displacement correction position Ob5 of the hole P5. It is a flowchart which shows a thermal displacement correction position calculation process. 2nd embodiment: It is a table | surface which shows the information memorize | stored in a database. 3rd embodiment: It is a figure which shows the relationship between the shape memorize | stored in the workpiece | work shape, the database, and a processing position.

(1. Machine configuration of machine tool)
As an example of a machine tool to which the thermal displacement correction apparatus and the thermal displacement correction method of the present invention are applied, a horizontal machining center is taken as an example and described with reference to FIG. The machine tool is a machine tool having three rectilinear axes (X, Y, Z axes) orthogonal to each other as drive axes.

  As shown in FIG. 1, the machine tool is movable in the Y-axis direction on the bed 1, the column 2 movable on the bed 1 in the X-axis direction, and the front surface of the column 2 (left surface in FIG. 1). A saddle 3, a rotary spindle 4 that is rotatably supported by the saddle 3 and holds a tool 5, and a table 6 that is movable on the bed 1 in the Z-axis direction and on which a workpiece W is placed.

(2. Shape of workpiece)
Next, an example of the workpiece W will be described with reference to FIGS. As shown in FIGS. 2 and 3, a box-shaped main body 11 formed in a bottomed box shape having a trapezoidal opening, and a flange portion 12 extending outward around the entire periphery of the opening edge of the box-shaped main body 11. And a plurality of ribs 13 to 16 fixed to the side surface and the bottom surface inside the box-shaped main body 11. Further, seven holes P1 to P7 are formed through the flange portion 12. The workpiece W is made of a metal such as aluminum or iron, for example. That is, the workpiece W has an asymmetric shape both in the X-axis direction and in the Y-axis direction. In particular, it has been found that the workpiece W having such an asymmetric shape undergoes a thermal displacement different from the theoretical value.

  Here, in the workpiece W, the holes P1 to P7 are set as processing parts. Although not shown in FIGS. 2 and 3, when the temperature of the workpiece W is the reference temperature T0, the coordinates of the center position O1 of the hole P1 are (X1, Y1), and the coordinates of the center position O2 of the hole P2 are ( X2, Y2), the coordinates of the center position O3 of the hole P3 are (X3, Y3), the coordinates of the center position O4 of the hole P4 are (X4, Y4), and the coordinates of the center position O5 of the hole P5 are (X5, Y5), the coordinates of the center position O6 of the hole P6 are (X6, Y6), and the coordinates of the center position O7 of the hole P7 are (X7, Y7).

(3. Procedure for thermal displacement correction)
A procedure relating to thermal displacement correction in the present embodiment will be described with reference to the flowchart of FIG. As shown in FIG. 4, first, in advance measurement in the measurement chamber, when the center position O1 of the hole P1 is used as a reference point, the angles θ2 to θ7 representing the thermal displacement directions of the holes P2 to P7 and the holes Linear expansion coefficients a2 to a7 of P2 to P7 are calculated and stored in a database to be described later (step S1). Thereafter, the holes P1 to P7 of the workpiece W are machined by the tool 5 while performing thermal displacement correction using information stored in the database (step S2). Details of each step will be described below.

(4. Pre-measurement of thermal displacement position)
The prior measurement in step S1 of FIG. 4 will be described with reference to FIG. 3 and FIG. In the above-described workpiece W, when the holes P1 to P7 are set as the processing parts, the thermal displacement positions of the holes P1 to P7 are actually measured. Here, the thermal displacement position means that the temperature Tw of the workpiece W changes from the reference temperature T0 with the origins of the center positions O2 to O7 of the holes P2 to P7 when the temperature Tw of the workpiece W is the reference temperature T0. Along with this, it means the coordinates where the center positions O2 to O7 of the holes P2 to P7 have moved.

  First, when actually measuring the thermal displacement position, the workpiece W is set in the measurement chamber, the temperature of the measurement chamber is set to the reference temperature T0, and the temperature of the workpiece W becomes stable. O1 to O7 were measured. The center positions O1 to O7 of the holes P1 to P7 at this time are set as reference positions of the holes P1 to P7.

  Subsequently, after the temperature of the measurement chamber is changed from the reference temperature T0 to a predetermined set temperature T, and the temperature of the workpiece W becomes stable, the center positions Oa2 (Xa2, Ya2) of the holes P2 to P7,. .., Oa7 (Xa7, Ya7) was measured. Here, since the hole P1 is used as a reference point, the center position (X1, Y1) of the hole P1 does not move even when the temperature of the measurement chamber is changed from the reference temperature T0.

  The center position O1 of the hole P1 when the temperature of the workpiece W is actually changed from the reference temperature T0 based on the center positions O2 to O7 at the reference temperature T0 and the center positions Oa2 to Oa7 at the set temperature T after the change. The thermal displacement direction and the amount of thermal displacement of the center positions O2 to O7 of the holes P2 to P7, which are predetermined points of the workpiece W when the points are set, are measured in advance.

  Here, the hole P5 will be described as an example and will be described in detail with reference to FIG. As shown in FIG. 5, by changing the temperature of the workpiece W from the reference temperature T0 to the set temperature T, the center position O5 of the hole P5 is thermally displaced to the center position Oa5. That is, the thermal displacement amount of the hole P5 was ΔP5. The thermal displacement amounts ΔP2 to ΔP7 of the holes P2 to P7 are calculated according to the equation (1).

  Further, the direction of thermal displacement of the hole P5 was a direction having an angle of θ5 counterclockwise from the Y axis plus direction. The heat displacement direction of the hole P5 was shifted from the straight line connecting the center positions O1 and O5 of the reference hole P1 and the hole P5. Angles θ2 to θ7 from the positive Y-axis direction that indicate the heat displacement directions of the holes P2 to P7 are calculated according to the equation (2).

  As shown in FIG. 3, when the temperature of the measurement chamber is a predetermined set temperature T as a result of the measurement, the center position O2 of the holes P2 to P7 is used when the center position O1 of the hole P1 is used as a reference point. The thermal displacement amounts ΔP2 to ΔP7 of O7 were amounts proportional to the size of the arrows in the holes P2 to P7 in FIG. In FIG. 3, the size of the arrow is enlarged as a length obtained by multiplying the actual thermal displacement amount by a set magnification. Furthermore, the thermal displacement directions of the center positions O2 to O7 of the holes P2 to P7 were the directions indicated by the arrows of the holes P2 to P7. Here, even when the temperature of the measurement chamber is changed from the set temperature T, the thermal displacement directions of the center positions O2 to O7 of the holes P2 to P7 are in the directions indicated by the arrows of the holes P2 to P7 in FIG. Matched.

  Subsequently, based on the actually measured values of the holes P1 to P7, the linear expansion coefficients a2 to a7 of the holes P2 to P7 were calculated when the center position O1 of the hole P1 was used as a reference point. Here, referring to FIG. 5 again, the hole P5 will be described as an example in detail. The linear expansion coefficient of the hole P5 with respect to the reference hole P1 was a5. The linear expansion coefficient a5 is calculated from the relationship between the temperature change ΔT (= T−T0) of the workpiece W and the thermal displacement amount ΔP5. Moreover, the linear expansion coefficients of the holes P3 to P7 were a3 to a7. Here, the linear expansion coefficient an is calculated according to the equation (3).

  As described above, when the center position O1 of the hole P1 is used as a reference point by prior measurement in the measurement chamber, the angles θ2 to θ7 representing the thermal displacement directions of the holes P2 to P7 and the holes P2 to P7 are shown. Are calculated and stored in a database to be described later.

(5. Control block configuration of machine tools)
Next, the control block configuration of the above-described machine tool will be described with reference to FIGS. As shown in FIG. 6, the machine tool includes a control device 30 that controls each motor 43 based on the NC program 41. Then, when the tool 5 moves relative to the work W, the work W is processed by the tool 5. The workpiece W is processed while coolant is applied to the workpiece W. Here, the temperature Tw of the workpiece W is affected by the room temperature Tr and the coolant temperature Tc. However, the temperature of the coolant temperature Tc is controlled so as to coincide with the room temperature Tr. Therefore, the temperature Tw of the workpiece W substantially matches the coolant temperature Tc.

  In order to perform temperature control of the coolant temperature Tc, the machine tool is provided with a coolant temperature sensor 42 for measuring the coolant temperature Tc. In the present embodiment, the control device 30 performs thermal displacement correction using the coolant temperature Tc measured by the coolant temperature sensor 42. In the thermal displacement correction described below, the coolant temperature Tc is used. The coolant temperature Tc is used as an estimated value of the temperature Tw of the workpiece W. That is, the coolant temperature sensor 42 indirectly measures the temperature Tw of the workpiece W.

  The control device 30 includes a reference control value calculation unit 31, a database 32, a thermal displacement correction position calculation unit 33, a correction unit 34, and each axis driver 35. The reference control value calculation unit 31 calculates a reference position control value based on the command value of the NC program 41 and the current position of each axis motor 43. The reference position control value is a position control value for each axis motor 43 before performing thermal displacement correction described later.

  As described above with reference to FIGS. 3 and 5, the database 32 includes information measured in advance when the temperature Tw of the workpiece W is actually changed in the measurement chamber, specifically, the center position of the hole P1. When O1 is a reference point, angles θ2 to θ7 and linear expansion coefficients a2 to a7 representing the thermal displacement directions in the holes P2 to P7 are stored. That is, as shown in FIG. 7, the database 32 stores linear expansion coefficients a <b> 2 to a <b> 7 and angles θ <b> 2 to θ <b> 7 representing thermal displacement directions in association with the holes P <b> 2 to P <b> 7.

  The thermal displacement correction position calculation unit 33 calculates a thermal displacement correction position Obn corresponding to the reference position control value calculated by the reference control value calculation unit 31. The process by the thermal displacement correction position calculation unit 33 will be described with reference to the flowchart of FIG. Furthermore, the thermal displacement correction position Obn calculated by the thermal displacement correction position calculation unit 33 will be described with reference to FIGS. 6 and 8. FIG. 8 illustrates the hole P5 as an example.

  The thermal displacement correction position calculation unit 33 acquires the reference position control value output from the reference control value calculation unit 31, that is, which of the holes P1 to P7 as the processing positions (step S11). Subsequently, the thermal displacement correction position calculation unit 33 acquires the linear expansion coefficient an and the angle θn corresponding to the hole Pn that is the acquired processing position from the database 32 (step S12). Subsequently, the coolant temperature Tc is acquired from the coolant temperature sensor 42 (step S13).

  The thermal displacement correction position calculation unit 33 then calculates the hole according to the equation (4) based on the linear expansion coefficient an of the corresponding hole Pn acquired from the database 32 and the coolant temperature Tc measured by the coolant temperature sensor 42. A thermal displacement amount ΔPbn of the hole Pn corresponding to the center position O1 of P1 as a reference point is calculated (step S14).

  Subsequently, the thermal displacement correction position calculator 33 calculates the hole P1 according to the equation (5) based on the calculated thermal displacement amount ΔPbn and the angle θn indicating the thermal displacement direction of the corresponding hole Pn acquired from the database 32. The thermal displacement correction position Obn of the hole Pn corresponding to the center position O1 is calculated. Here, as described above, the thermal displacement correction positions Ob2 to Ob7 are the temperatures Tw of the workpiece W being the reference temperature with the center positions O2 to O7 of the holes P2 to P7 at the reference temperature T0 as the origin. This is the coordinates where the center positions O2 to O7 of the holes P2 to P7 have moved with the change from T0. According to the equation (5), the X-axis coordinate ΔPbxn and the Y-axis coordinate ΔPbyn of the thermal displacement correction position Obn of each hole Pbn are calculated. Then, the process ends.

  Returning to FIG. 6, the description of the functional block configuration of the control device 30 is continued. The correction unit 34 corrects the thermal displacement correction positions Ob2 to Ob7 calculated by the thermal displacement correction position calculation unit 33 with respect to the reference position control value calculated by the reference control value calculation unit 31, thereby correcting the correction position. Calculate the control value. The correction unit 34 outputs the corrected position control value to each axis driver 35 to drive each axis driver 35. Each axis driver 35 drives each axis motor 43. That is, when the correction unit 34 processes the holes O2 to O7 of the workpiece W with the tool 5, the tool 5 with respect to the center position O1 of the hole P1 that is the reference point of the workpiece W based on the thermal displacement correction positions Ob2 to Ob7. Correct the relative position of.

  As described above, the thermal displacement direction and the linear expansion coefficient of the center positions O2 to O7 of the other holes P2 to P7 with respect to the center position O1 of the hole P1, which is the reference point of the workpiece W, are actually measured through experiments. It is acquired by That is, the thermal displacement direction and the linear expansion coefficient as measured values are stored in the database 32. Then, the thermal displacement correction positions Ob2 to Ob7 corresponding to the temperature Tw of the workpiece W at the time of machining are calculated using the thermal displacement direction and the linear expansion coefficient as measured values stored in the database 32. Therefore, the thermal displacement correction positions Ob2 to Ob7 for performing the thermal displacement correction can be matched with the actual thermal displacement position of the workpiece W with high accuracy. As a result, processing accuracy can be improved.

  Further, the respective linear expansion coefficients a2 to a7 are stored in the database 32 for the holes P2 to P7 other than the hole P1 as the reference point. Therefore, the thermal displacement amounts ΔPb2 to ΔPb7 of the center positions O2 to O7 of the holes P2 to P7 are calculated using the linear expansion coefficients a2 to a7 corresponding to the holes P2 to P7. As a result, the thermal displacement amounts ΔPb2 to ΔPb7 at the center positions O2 to O7 of the holes P2 to P7 can be reliably matched with the actual thermal displacement amount of the workpiece W.

<Second embodiment>
A second embodiment of information stored in the database 32 will be described with reference to FIG. As shown in FIG. 10, in the database 32, a constant value a _ave is stored for all the holes P2 to P7 as the linear expansion coefficients in the holes P2 to P7. The linear expansion coefficient a _ave is an average value of the linear expansion coefficients a1 to a7 in the actually measured holes P2 to P7. Naturally, the linear expansion coefficient a _ave , which is an average value, does not always coincide with the theoretical value. The thermal displacement correction position calculation process by the thermal displacement correction position calculation unit 33 is the same process as described above, _except that the linear expansion coefficient a _ave is different.

As described above, by using the average value of the values measured by experiments as the linear expansion coefficient a _ave used for calculating the thermal displacement amount ΔPbn in the thermal displacement correction position calculation unit 33, the linear expansion coefficient a _ave is actually calculated. A value approximate to the linear expansion coefficient of the workpiece W can be obtained. As a result, the thermal displacement amount ΔPbn in each of the holes P2 to P7 can be matched with the actual thermal displacement amount with high accuracy. Furthermore, by using a constant value for the plurality of holes P2 to P7 as the linear expansion coefficient a _ave , the calculation processing speed of the thermal displacement amount ΔPbn in the thermal displacement correction position calculation unit 33 can be increased. Thereby, since high followability to a processing position can be secured, processing accuracy can be improved.

<Third embodiment>
In the above, the case where the holes P1 to P7 of the workpiece W were used as the machining parts was described. In addition, the above-described thermal displacement correction can be applied using the surface of the workpiece W shown in FIG. The processing part such as the surface of the workpiece W may be a curved part or a planar part.

  In this case, as shown in FIG. 11, actual thermal displacement positions for a plurality of points P11, P12, P13, and P14 in the machining part of the workpiece W are measured in advance and stored in the database 32. Then, at the time of machining, the thermal displacement correction at the machining position P of the workpiece W corresponding to the reference position control value calculated by the reference control value calculation unit 31 is performed by interpolation using information stored in the database 32. The position ΔP is calculated. Specifically, the angle θ representing the thermal displacement direction at the machining position P of the workpiece W is selected from a plurality of positions P11, P12, P13, which are adjacent to the machining position P from the information stored in the database 32. Calculation is performed by interpolating the angle θ representing the thermal displacement direction at P14. Further, the linear expansion coefficient a at the machining position P of the workpiece W is obtained by calculating the linear expansion coefficient at a plurality of positions P11, P12, P13, P14 adjacent to the machining position P from the information stored in the database 32. Calculated by interpolation. As described in the second embodiment, a constant value as an average value can be used as the linear expansion coefficient. Then, the correction unit 34 performs surface machining while performing thermal displacement correction using the thermal displacement correction position.

<Others>
In the above embodiment, the coolant temperature Tc is used for the temperature Tw of the workpiece W. In addition, if the temperature Tw of the workpiece W matches the room temperature Tr, the room temperature Tr can be measured and the measured room temperature Tr can be applied as the temperature Tw of the workpiece W. Moreover, the temperature Tw of the workpiece | work W itself can be directly measured by using a non-contact temperature sensor.

5: Tool, 30: Control device, 31: Reference control value calculation unit 32: Database, 33: Thermal displacement correction position calculation unit, 34: Correction unit 42: Coolant temperature sensor P1: Reference hole, P2 to P7: Thermal displacement correction Target hole, W: Workpiece

Claims (6)

A thermal displacement correction device that corrects the relative position of the tool with respect to a reference point of the workpiece based on the thermal displacement of the workpiece,
A database for storing a thermal displacement direction of a predetermined point of the workpiece with respect to a reference point of the workpiece measured in advance when the temperature of the workpiece is actually changed;
Temperature measuring means for directly or indirectly measuring the temperature of the workpiece during processing;
Based on the thermal displacement direction of the predetermined point of the workpiece stored in the database, the temperature of the workpiece measured by the temperature measuring means, and the linear expansion coefficient of the workpiece, the predetermined point of the workpiece at the time of machining Thermal displacement correction position calculating means for calculating the thermal displacement correction position of
Correction means for correcting a relative position of the tool with respect to a reference point of the workpiece based on the thermal displacement correction position when processing the predetermined point of the workpiece with the tool;
A thermal displacement correction device comprising: In claim 1,
The database is a coefficient of linear expansion of the workpiece calculated based on a thermal displacement amount of the predetermined point of the workpiece with respect to a reference point of the workpiece measured in advance when the temperature of the workpiece is actually changed, and the temperature of the workpiece. Remember more,
The thermal displacement correction position calculating unit calculates a thermal displacement correction position at a predetermined point of the workpiece using a linear expansion coefficient of the workpiece stored in the database. In claim 2,
The predetermined points of the workpiece are plural,
The thermal displacement correction device, wherein the linear expansion coefficient stored in the database is an average value of linear expansion coefficients at a plurality of predetermined points of the workpiece. In claim 2,
The processing part of the workpiece is a plurality of holes,
The predetermined points of the workpiece are the holes, respectively.
The linear expansion coefficient stored in the database is a linear expansion coefficient of each predetermined point of the workpiece,
The thermal displacement correction position calculating means calculates a thermal displacement correction position of each predetermined point of the workpiece using a linear expansion coefficient of each predetermined point of the workpiece stored in the database. . In claim 1,
The processing part of the workpiece is a curved surface part or a planar part,
The predetermined points of the workpiece are a plurality of points included in the processed part of the workpiece,
The thermal displacement direction stored in the database is the thermal displacement direction of each predetermined point of the workpiece,
The thermal displacement correction position calculating means, the thermal displacement direction depending on the machining point of the workpiece is calculated by interpolation using the thermal displacement direction of each of the predetermined points of the work stored in said database Thermal displacement correction device. A thermal displacement correction method for correcting a relative position of a tool with respect to a reference point of the workpiece based on a thermal displacement of the workpiece,
A measurement step of measuring in advance a thermal displacement direction of a predetermined point of the workpiece with respect to a reference point of the workpiece when the temperature of the workpiece is actually changed;
A temperature measurement step for directly or indirectly measuring the temperature of the workpiece during processing;
Based on the thermal displacement direction of the predetermined point of the workpiece measured in advance, the temperature of the workpiece measured in the temperature measurement step, and the linear expansion coefficient of the workpiece, the thermal displacement of the predetermined point of the workpiece during processing A thermal displacement correction position calculating step for calculating a correction position;
A correction step of correcting a relative position of the tool with respect to a reference point of the workpiece based on the thermal displacement correction position when processing the predetermined point of the workpiece with the tool;
A thermal displacement correction method comprising:

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