JP7138284B2 - Three-dimensional measuring machine and three-dimensional measuring method - Google Patents

Description

The present invention relates to a three-dimensional measuring machine and a three-dimensional measuring method, and more particularly to a three-dimensional measuring machine and a three-dimensional measuring method for correcting measurement results.

2. Description of the Related Art A three-dimensional measuring machine is known that measures the shape of a workpiece by obtaining three-dimensional coordinates of a plurality of measurement positions on the workpiece, which is an object to be measured. In such a three-dimensional measuring machine, the work may expand or contract depending on the temperature of the work, making it impossible to obtain correct measurement results.

On the other hand, there is known work temperature correction in which a temperature sensor is attached to a work and the acquired three-dimensional coordinates are corrected based on the temperature read by the sensor and the coefficient of thermal expansion of the work material designated by the operator.

However, there is a temperature difference on the surface of the workpiece, and the larger the workpiece, the more noticeable this temperature difference. Therefore, there is a problem that an accurate result cannot be obtained with a single temperature sensor.

In order to solve such problems, it is conceivable to use a plurality of temperature sensors. Patent Literature 1 discloses a technique of measuring the temperature of a workpiece using a plurality of temperature sensors and correcting the measurement results using the temperature of the workpiece and the coefficient of linear expansion of the workpiece.

JP-A-11-190617

However, using multiple temperature sensors increases cost. In addition, the temperature sensor itself and the cable of the temperature sensor become complicated, which interferes with the measurement. In particular, when using a contact-type probe, there is a risk that it will interfere with the movement path of the probe and cause interference between the probe and the temperature sensor.

Also, the number of temperature sensors that can be used is practically limited to two or three. However, even if two or three temperature sensors are used, it is often not possible to obtain the results desired by the user. There is also the problem that there is no end to the search, such as what position should be placed and how many should be placed.

Furthermore, there is a problem that the conventional work temperature correction does not take into consideration the expansion difference in the three-dimensional XYZ directions. That is, when the XYZ coordinates of the probing point are multiplied by the same temperature correction coefficient, an accurate result cannot be obtained unless the expansion is uniform in the XYZ directions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a three-dimensional measuring machine and a three-dimensional measuring method that can appropriately correct the measured three-dimensional coordinates according to the temperature of the object to be measured. .

In order to achieve the above object, one aspect of the three-dimensional measurement method includes a measurement object measurement step of obtaining three-dimensional coordinates of the measurement position of the measurement object in mutually orthogonal three-axis directions using a measurement sensor; a temperature measurement step of measuring the temperature of the object to be measured by a temperature sensor; A correction coefficient acquisition step of acquiring a temperature correction coefficient for each axial direction in the measured temperature from the relationship with the three-dimensional coordinates, and a correction step of correcting the three-dimensional coordinates of the measurement position using the acquired temperature correction coefficients. It is a three-dimensional measurement method that has

According to this aspect, the three-dimensional coordinates of the measurement position of the measurement object are acquired by the measurement sensor, the temperature of the measurement object is measured by the single temperature sensor, and the temperature correction coefficient for each axial direction is acquired. Since the three-dimensional coordinates of the measurement position are corrected using the calculated temperature correction coefficient, the measured three-dimensional coordinates can be appropriately corrected for each axial direction according to the temperature of the object to be measured.

The correction coefficient acquisition step acquires the temperature correction coefficient of the position closest to the measurement position among the plurality of positions, and the correction step corrects the three-dimensional coordinates of the measurement position using the temperature correction coefficient of the position closest to the measurement position. preferably. With this, it is possible to appropriately correct the three-dimensional coordinates of the measurement position.

The correction coefficient acquisition step includes an interpolation step of interpolating the three-dimensional coordinates of the actual measurement values at a plurality of temperatures of the reference measurement object from the three-dimensional coordinates of the actual measurement values at the multiple locations at the multiple temperatures; and a calculating step of calculating temperature correction coefficients for a plurality of positions in the measured temperature from the three-dimensional coordinates and the three-dimensional coordinates of the interpolated measured values. With this, it is possible to appropriately acquire temperature correction coefficients at a plurality of positions in the measured temperature.

In the interpolation step, one section including the measured temperature is determined among a plurality of temperature sections divided by the plurality of temperatures, and the three-dimensional coordinates of the measured value at the upper limit temperature and the measured value at the lower limit temperature of the determined one section are determined. It is preferable to linearly interpolate the three-dimensional coordinates of the measured values at a plurality of positions in the temperature measured using the three-dimensional coordinates. As a result, it is possible to appropriately interpolate the three-dimensional coordinates of the measured values of the plurality of positions at the measured temperature.

In order to achieve the above object, one aspect of a three-dimensional measuring machine includes a measurement sensor for acquiring three-dimensional coordinates of a measurement position of an object to be measured in mutually orthogonal three-axis directions, and a unit for measuring the temperature of the object to be measured. A memory that stores the relationship between one temperature sensor, the three-dimensional coordinates of design values at a plurality of positions of the reference measurement object, and the three-dimensional coordinates of actual measurement values obtained by measuring a plurality of positions of the reference measurement object at a plurality of temperatures. a correction coefficient acquisition unit that reads the stored relationship and acquires temperature correction coefficients for each axial direction in the temperature measured by the temperature sensor; and corrects the three-dimensional coordinates of the measurement position using the acquired temperature correction coefficients. and a correction unit.

According to this aspect, the measured three-dimensional coordinates can be appropriately corrected for each axial direction according to the temperature of the object to be measured.

According to the present invention, it is possible to appropriately correct the measured three-dimensional coordinates according to the temperature of the object to be measured.

FIG. 1 is a diagram showing a three-dimensional measuring machine. FIG. 2 is a block diagram showing the electrical configuration of the three-dimensional measuring machine. FIG. 3 is an external perspective view of the probe head. FIG. 4 is a schematic diagram showing a schematic configuration of a line sensor. FIG. 5 is a flow chart showing the processing of the three-dimensional measurement method. FIG. 6 is a flowchart showing processing for acquiring a work temperature correction file. FIG. 7 is a diagram showing an example of a work temperature correction file. FIG. 8 is a diagram showing an image in which the coordinates of the design values and the coordinates of the measured values are superimposed. FIG. 9 is a flow chart showing the correction coefficient calculation process. FIG. 10 is a diagram showing an example of temperature correction coefficients. FIG. 11 is a flow chart showing the correction process.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Configuration of 3D measuring machine>
FIG. 1 is a diagram (perspective view and block diagram) showing a three-dimensional measuring machine 10 according to one embodiment of the present invention. FIG. 2 is a block diagram showing the electrical configuration of the three-dimensional measuring machine 10. As shown in FIG. The three-dimensional measuring machine 10 measures the three-dimensional coordinates (coordinate values in the X-axis direction, the Y-axis direction, and the Z-axis direction) of each measurement point (measurement position) of the workpiece W, which is an object to be measured, and measures the workpiece W Calculate the shape of The shape of the workpiece W here includes the three-dimensional shape, two-dimensional shape, surface shape, contour shape, and various dimensions such as length and diameter of the workpiece W.

Note that the X-axis, Y-axis, and Z-axis in FIG. 1 are a machine coordinate system that is determined based on a machine coordinate origin specific to the three-dimensional measuring machine 10 . As used herein, the term “three-dimensional coordinates” refers to coordinates based on the machine coordinate origin of the three-dimensional measuring machine 10 .

As shown in FIG. 1, the three-dimensional measuring machine 10 includes a pedestal 12, a table 14 (surface plate) provided on the pedestal 12, right Y carriages 16R and left Y carriages 16R and 16R erected on both ends of the table 14, respectively. A carriage 16L and an X guide 18 connecting the upper portions of the right Y carriage 16R and the left Y carriage 16L are provided. The right Y carriage 16R, the left Y carriage 16L, and the X guide 18 constitute a portal frame 19. As shown in FIG.

A workpiece W is placed on the upper surface of the table 14 . In addition, sliding surfaces on which the right Y carriage 16R and the left Y carriage 16L slide along the Y-axis direction are formed on the upper surface and side surfaces of both ends of the table 14 . An air bearing (not shown) is provided at a position facing the sliding surface of the table 14 on the right Y carriage 16R and the left Y carriage 16L. As a result, the right Y carriage 16R and the left Y carriage 16L become movable along with the X guide 18 in the Y-axis direction.

An X carriage 20 is attached to the X guide 18 . The X guide 18 has a sliding surface along the X axis direction on which the X carriage 20 slides. Also, the X carriage 20 is provided with an air bearing (not shown) at a position facing the sliding surface of the X guide 18 . This allows the X carriage 20 to move freely in the X-axis direction.

A Z carriage (also referred to as a Z spindle) 22 is attached to the X carriage 20 . The X carriage 20 is also provided with an air bearing (not shown) for guiding the Z carriage 22 in the Z axis direction. Thereby, the Z carriage 22 is held by the X carriage 20 so as to be movable in the Z-axis direction. A probe head 24 is attached to the lower end of the Z carriage 22 .

The three-dimensional measuring machine 10 includes a Y-axis driving unit that moves the portal frame 19 in the Y-axis direction, an X-axis driving unit that moves the X-carriage 20 in the X-axis direction, and a Z-carriage 22 that moves in the Z-axis direction. A first drive 26 is provided which includes a Z-axis drive for moving the . As a result, the probe head 24 and a line sensor 32, which will be described later, can be moved in three axial directions (XYZ axial directions) orthogonal to each other.

A Y-axis linear scale (not shown) is provided at the end of the table 14 on the right Y carriage 16R side. The X guide 18 is provided with an X-axis linear scale (not shown), and the Z carriage 22 is provided with a Z-axis linear scale (not shown).

On the other hand, the right Y carriage 16R is provided with a Y-axis detector (not shown) for reading the Y-axis linear scale. The X carriage 20 is also provided with an X-axis detection section (not shown) and a Z-axis detection section (not shown) for reading the X-axis linear scale and the Z-axis linear scale, respectively. The detection results of each detection section 28 including the X-axis detection section, Y-axis detection section, and Z-axis detection section are output to the computer 42 via the controller 30 .

In this embodiment, the shape of the workpiece W is measured using a line sensor 32 (3D scanner), which is an example of a non-contact probe, as a measurement sensor.

FIG. 3 is an external perspective view of the probe head 24 detachably holding the line sensor 32. As shown in FIG. As shown in FIG. 3, the probe head 24 is, for example, a 5-axis simultaneous control measuring head with a stepless positioning mechanism. The probe head 24 is provided with a second drive unit 34 (see FIG. 2) such as a motor that rotatably holds and rotates the line sensor 32 about two rotation axes R1 and R2 that are perpendicular to each other. It is Thereby, the probe head 24 can steplessly adjust the rotation angle φ of the line sensor 32 about the rotation axis R1 and the rotation angle θ of the line sensor 32 about the rotation axis R2. As a result, the probe head 24 can arbitrarily displace (rotate) the posture of the line sensor 32 .

The probe head 24 is provided with a rotation angle detector (not shown) such as a rotary encoder for detecting the rotation angles θ and φ of the line sensor 32, respectively. A result of detection by this rotation angle detection unit is output to the computer 42 via the controller 30 . A rotation angle detector is included in each detector 28 .

Returning to the description of FIGS. 1 and 2 , the three-dimensional measuring machine 10 has a temperature sensor 36 . A temperature sensor 36 is used to measure the temperature of the work W. FIG. In this embodiment, one temperature sensor 36 is attached using a magnet or the like at a position where the shape measurement of the workpiece W is not hindered.

A thermistor, a thermocouple, or the like can be used as the temperature sensor 36 . The temperature sensor 36 converts an analog signal that changes according to temperature into a digital voltage signal and outputs it to the controller 30 .

The controller 30 is a control device that controls operations of the three-dimensional measuring machine 10 and the probe head 24 . Under the control of the computer 42 , the controller 30 controls the first driving section 26 and the second driving section 34 to change the position and posture of the line sensor 32 .

The controller 30 is also provided with an operation unit 38 for the user to operate the three-dimensional measuring machine 10 .

Further, the controller 30 is connected to the above-described detectors 28, the line sensor 32, and the like. A computer 42 is connected to the controller 30 via a communication network 40 such as a LAN (Local Area Network) using TCP/IP (Transmission Control Protocol/Internet Protocol) as a communication protocol. and other signals to the computer 42.

Various arithmetic processing units such as a personal computer are used as the computer 42 . The computer 42 includes a storage section 44 , a correction coefficient acquisition section 46 and a correction section 48 . In the storage unit 44, software 44A for confirming the instruction of the measurement operation and the measurement result is installed. The computer 42 executes software 44A and controls the operation of each part of the three-dimensional measuring machine 10 in an integrated manner.

A correction coefficient acquisition unit 46 acquires a temperature correction coefficient for each axial direction. A correction unit 48 corrects the three-dimensional coordinates of the measurement position using the temperature correction coefficient. Details of the correction coefficient acquisition unit 46 and the correction unit 48 will be described later.

The computer 42 also controls the first driving section 26 and the second driving section 34 via the controller 30 to cause the line sensor 32 to measure the measurement position of the workpiece W. FIG. Further, the computer 42 calculates the shape of the work W based on the measurement results (three-dimensional coordinates) of the measurement position of the work W by the line sensor 32 and the like.

FIG. 4 is a schematic diagram showing a schematic configuration of the line sensor 32. As shown in FIG. As shown in FIG. 4, the line sensor 32 is, for example, a diffuse reflection receiving type laser displacement meter (also referred to as a laser probe) employing a triangulation method. The diffuse reflection receiving type line sensor 32 includes an incident portion 32a and a detection portion 32b.

The incident part 32a is composed of a semiconductor laser light source, a projection lens (not shown), and the like, and makes the laser beam LA incident on the workpiece W at the measurement position. The laser beam LA incident on the measurement position is diffusely reflected, and the diffusely reflected laser beam LA is incident on the detector 32b.

The detection unit 32b includes a light receiving lens and a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type imaging device (not shown). A laser beam LA is made incident on the imaging surface of the imaging element. This imaging device has an imaging surface in which a plurality of pixels are arranged two-dimensionally, and detects light for each pixel. The aforementioned laser beam LA is incident on this imaging surface as spot light.

Here, the incident position (spot position) of the laser beam LA on the imaging surface of the imaging element is displaced according to the positional relationship between the line sensor 32 and the measurement position where the laser beam LA is diffusely reflected. Therefore, the distance from the line sensor 32 to the measurement position, which is the reflection point of the laser light LA, can be detected based on the detection result of the amount of light received for each pixel of the imaging device.

The detection unit 32b outputs a light reception signal indicating the amount of light received for each pixel of the image sensor to the computer 42 via the controller 30 as a detection result of the diffusely reflected laser beam LA. Thereby, the computer 42 detects the three-dimensional coordinates of the measurement position of the work W based on the distance detection result by the line sensor 32 and the detection result of each detection section 28 described above. By moving the line sensor 32 along the measurement surface of the work W, the three-dimensional coordinates of each measurement position on the measurement surface can be continuously detected along the moving direction of the line sensor 32 .

<Three-dimensional measurement method>
A three-dimensional measuring machine 10 is installed in a measuring room at a predetermined room temperature (for example, 20° C.). On the other hand, the work W may be in a state immediately after being machined, or may be in a state of being left for a while in another room after being machined. Therefore, the temperature of the workpiece W is not always the same as the room temperature. Therefore, the three-dimensional measuring machine 10 corrects the acquired three-dimensional coordinates of the measurement position of the work W according to the temperature of the work W. FIG.

FIG. 5 is a flow chart showing processing of a three-dimensional measuring method for measuring the workpiece W with the three-dimensional measuring machine 10. As shown in FIG. As shown in FIG. 5, the three-dimensional measurement method includes a correction coefficient acquisition step (step S1), a measurement object measurement step (step S2), and a correction step (step S3).

In step S1, the three-dimensional measuring machine 10 measures the temperature of the work W with the single temperature sensor 36, and measures the three-dimensional coordinates of the design values at a plurality of positions of the master work Wm serving as a reference and the master at a plurality of temperatures. A three-dimensional temperature correction coefficient for the measured temperature is acquired from the relationship with the three-dimensional coordinates of the measured values obtained by measuring a plurality of positions of the workpiece Wm.

In step S2, the three-dimensional measuring machine 10 measures the shape of the workpiece W. FIG. Here, the line sensor 32 acquires the three-dimensional coordinates of the desired measurement position of the workpiece W. FIG.

At step S3, the three-dimensional measuring machine 10 corrects the three-dimensional coordinates obtained at step S2 using the temperature correction coefficient obtained at step S1.

The order of step S1 and step S2 may be reversed. Details of each step will be described below.

[Work temperature correction file acquisition process]
The three-dimensional measuring machine 10 corrects the acquired three-dimensional coordinates using the work temperature correction file. Therefore, the three-dimensional measuring machine 10 needs to obtain a work temperature correction file for the work W in advance. Here, processing for obtaining a work temperature correction file will be described. FIG. 6 is a flowchart showing processing for acquiring a work temperature correction file.

In step S11, the computer 42 acquires the design values of the work W to be three-dimensionally measured. The design values of the work W are known information obtained from 3D-CAD (3 Dimension-Computer Aided Design) (not shown). The computer 42 acquires design values of the workpiece W from 3D-CAD via a communication network such as LAN. Further, the computer 42 converts the point group of the work W from the acquired design values of the work W into three-dimensional coordinates based on the machine coordinate origin of the three-dimensional measuring machine 10 .

In step S12, the user sets temperature Ts _i (i=1 to n). The minimum value of the temperature _Tsi is the minimum value of the temperature of the workpiece W assumed under the measurement environment. For example, the temperature is the temperature in which the workpiece W is left overnight in the middle of winter. The maximum value of the temperature _Tsi is the maximum value of the temperature of the workpiece W assumed under the measurement environment. For example, the temperature is the temperature immediately after processing. The temperature _Tsi is set at regular intervals, such as 5° C. intervals, between the minimum and maximum values. Here, the temperature is _first set to Ts1.

Next, prepare a master work Wm (an example of a reference measurement object) that has the same shape and material as the work W to be measured and that satisfies a predetermined accuracy. In step S13, the master work Wm is placed in a constant temperature bath (not shown), and the master work Wm is heated or cooled so that the temperature at the mounting position of the temperature sensor reaches _Tsi set in step S12. Here, the temperature of the constant temperature bath is set so that the temperature of the master work Wm is _Ts1 .

In step S14, the master work W whose temperature at the mounting position of the temperature sensor has reached _Tsi is placed on the table 14 of the three-dimensional measuring machine 10 in the measuring room at 20°C. Here, the masterwork Wm is at temperature _Ts1 .

In step S15, the line sensor 32 acquires actual measurement values of the point group of the master work Wm. Here, the measured values (x1 ₁ , y1 ₁ , z1 ₁ ) of the point corresponding to the coordinates (X1, Y1, Z1) of the design values, and the measured values of the point corresponding to the coordinates (X2, Y2, Z2) of the design values ( _{x2 1} , _{y2 1} , _{z2 1} ), . , _Ym , _Zm ) is _obtained .

In step S16, it is determined whether or not measurements have been performed at all temperatures Ts ₁ to Ts _n . If the measurements have been performed at all temperatures, the processing of this flow chart ends. Here, since _only the temperature Ts1 was measured, the process returns to step S12, the temperature is set to _Ts2 , and the same processing is performed. This process is repeated until the temperature _Tsn .

The computer 42 calculates the relationship between the three-dimensional coordinates of the design values of the plurality of positions of the master work Wm thus obtained and the three-dimensional coordinates of the actual measurement values obtained by measuring the plurality of positions of the master work Wm at a plurality of temperatures. It is stored in the storage unit 44 as a correction file. Also, the computer 42 reads the work temperature correction file from the storage unit 44 when the application is started, and holds it in a memory (not shown).

FIG. 7 is a diagram showing an example of a work temperature correction file. Moreover, FIG. 8 is a diagram showing an image in which the design values and the actual measurement values are superimposed. In FIG. 8, the three-dimensional difference based on the temperature sensor mounting position is converted into millimeters and represented by shading.

[Correction coefficient calculation step (step S1)]
Next, the details of the correction coefficient calculation process will be described. FIG. 9 is a flow chart showing the correction coefficient calculation process.

First, the user places the workpiece W whose shape is to be measured on the table 14 of the three-dimensional measuring machine 10 . Also, a temperature sensor 36 is attached to the work W. As shown in FIG. There is one temperature sensor 36 . The position where the temperature sensor 36 is attached is not limited.

In step S<b>21 (an example of the temperature measurement process), the computer 42 measures the temperature of the workpiece W using the temperature sensor 36 . The temperature measured by temperature sensor 36 is input to computer 42 via controller 30 . Let the measured temperature be the reading temperature Ts.

In step S22, the computer 42 selects a section (an example of one section) including the read temperature Ts obtained in step S21 from among a plurality of sections (an example of the temperature section) divided by a plurality of temperatures Ts ₁ to Ts _n . judge. Here, the value of the integer k that satisfies Equation 1 below is obtained, and Ts _k to Ts _k+1 is set as the interval of the reading temperature Ts.

Ts _k ≤ Ts ≤ Ts _{k + 1} (Equation 1)
In step S23 (an example of the interpolation step), the computer 42 interpolates the three-dimensional coordinates of the measured values at the reading temperature Ts, and coordinates (xj _w , yj _w , zj _w ) (j=1 to m) of the linearly interpolated measured values. ). Here, the three-dimensional coordinates of the measured values at the upper limit temperature Tsk ₊₁ and the three-dimensional coordinates of the measured values at the lower limit temperature _Tsk are read out from the workpiece temperature correction file held in the memory (not shown), and the X coordinates xj _w , Y Linear interpolation is performed using Equations 2, 3, and 4 below for each of the coordinate yj _w and the Z coordinate zj _w .

xj _w = {(xj _k+1 −xj _k )/(Ts _k+1 −Ts _k )}×(Ts−Ts _k )+xj _k (equation 2)
yj _w = {(yj _k+1 −yj _k )/(Ts _k+1 −Ts _k )}×(Ts−Ts _k )+yj _k (equation 3)
zj _w = {(zj _k+1 −zj _k )/(Ts _k+1 −Ts _k )}×(Ts−Ts _k )+zj _k (equation 4)
In this way, linear interpolation is performed on the three-dimensional coordinates of the measured values at a plurality of positions at the measured temperature.

In step S24 (an example of a calculation process), the correction coefficient acquisition unit 46 calculates a temperature correction coefficient for each axial direction at a plurality of positions at the read temperature Ts. Here, the temperature correction coefficient βxj in the X-axis direction, the temperature correction coefficient βyj in the Y-axis direction, and the temperature correction coefficient βzj in the Z-axis direction (j=1 to m) are calculated respectively.

βxj=Xj/ _xjw (Formula 5)
βyj=Yj/ _yjw (Formula 6)
βzj=Zj/ _zjw (Formula 7)
That is, the three-dimensional coordinate of the design value is divided by the three-dimensional coordinate of the actually measured value obtained by interpolating, and the temperature correction coefficient at the reading temperature Ts is calculated.

FIG. 10 is a diagram showing an example of temperature correction coefficients. Here, an example is shown in which Ts ₂ to Ts ₃ is the section of read temperature Ts. As shown in FIG. 10, the temperature correction coefficients (βx1, βy1, βz1) at the coordinates (x1 _w , y1 _w , z1 _w ) of the linear interpolation actual measurement values, the coordinates (x2 _w , y2 w , y2 _w , z2 _w ) point temperature correction coefficients ( _βx2 , _βy2 , _βz2 ), . , the temperature correction coefficients (βxm, βym, βzm) at the coordinates (xm _w , ym _w , zm _w ) of the linearly interpolated measured values are calculated.

In step S25, it is determined whether or not to end the correction coefficient calculation. When ending correction coefficient calculation, the processing of this flowchart ends. In general, the temperature of the workpiece W is measured in real time such as at intervals of 0.1 seconds. Therefore, the correction coefficient is also updated according to the measured temperature.

[Measurement object measurement step (step S2)]
In step S<b>2 , the three-dimensional measuring machine 10 acquires three-dimensional coordinates of a desired measurement position of the work W placed on the table 14 in three mutually orthogonal axial directions by the line sensor 32 . Hereinafter, the measurement position from which the three-dimensional coordinates are acquired is called a probing point.

[Correction step (step S3)]
Next, details of the correction process will be described. FIG. 11 is a flow chart showing the correction process.

At step S31, the three-dimensional coordinates of the probing points obtained at step S2 are input to the computer . Here, it is assumed that the three-dimensional coordinates are (Xp, Yp, Zp).

In step S32, the computer 42 searches the vicinity of the probing point, and among the points of the coordinates (xj _w , yj _w , zj _w ) (j=1 to m) of the linear interpolation actual measurement values, the probing points input in step S31 Determine the point with the closest distance to the point.

In step S33, the correction unit 48 temperature-corrects the probing points using the temperature correction coefficients βxj, βyj, and βzj of the points at the coordinates ( _xjw , _yjw , _zjw ) of the linearly interpolated measured values determined in step S32. do. That is, using the following equations 8, 9, and 10, the coordinates (Xc, Yc, Zc) of the points obtained by temperature-correcting the probing points in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, are calculated. .

Xc=βxj×Xp (Formula 8)
Yc=βyj×Yp (Formula 9)
Zc=βzj×Zp (Equation 10)
The computer 42 calculates the shape of the workpiece W based on the temperature-corrected three-dimensional coordinates of the plurality of probing points.

In this way, the three-dimensional coordinates of the probing point are corrected in three mutually orthogonal directions (X-axis direction, Y-axis direction, and Z-axis direction) using the three-dimensional temperature correction coefficients. Therefore, the shape of the work W can be accurately measured even when the temperature of the work W is low because the work W is left overnight in the middle of winter, or even when the temperature of the work W is high immediately after processing. becomes possible.

<Others>
Here, an example using a line sensor, which is a non-contact measurement sensor, has been described. By using a line sensor, high-speed measurement of multiple points is possible, and when there are a large number of point groups to be measured, it is possible to estimate them efficiently in a short time. In addition, it is possible to perform appropriate measurements even on materials that would otherwise be damaged by the contact method.

This embodiment can also employ a contact-type probe, which is a contact-type measurement sensor. Using a contact probe enables highly accurate measurement.

In this embodiment, the work temperature correction file acquisition process using the master work and the shape measurement of the work are both performed using the line sensor, but these may be performed using different measurement sensors. In the workpiece temperature correction file acquisition process, it is preferable to use a measurement sensor having the same measurement accuracy as or higher than the measurement accuracy of the measurement sensor used to measure the shape of the workpiece.

The technical scope of the present invention is not limited to the scope described in the above embodiments. Configurations and the like in each embodiment can be appropriately combined between each embodiment without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10... Three-dimensional measuring machine 12... Mounting frame 14... Table 16L... Carriage 16R... Carriage 18... Guide 19... Portal frame 20... Carriage 22... Carriage 24... Probe head 26... First drive part 28... Detection part 30... Controller 32 Line sensor 32a Incidence unit 32b Detection unit 34 Second drive unit 36 Temperature sensor 38 Operation unit 40 Communication network 42 Computer 44 Storage unit 44A Software 46 Correction coefficient acquisition unit 48 Correction unit

Claims (5)

a measuring object measuring step of acquiring three-dimensional coordinates of the measuring position of the measuring object in mutually orthogonal three-axis directions by the measuring sensor;
a temperature measurement step of measuring the temperature of the measurement object with a single temperature sensor;
Same shape and same material as the object to be measured From the relationship between the three-dimensional coordinates of the design values of the plurality of positions of the reference measurement object and the three-dimensional coordinates of the measured values of the plurality of positions of the reference measurement object at the plurality of temperatures, the a correction coefficient obtaining step of obtaining a temperature correction coefficient for each axial direction;
a correction step of correcting the three-dimensional coordinates of the measurement position using the acquired temperature correction coefficient;
A three-dimensional measurement method having The correction coefficient acquisition step acquires a temperature correction coefficient of a position closest to the measurement position among the plurality of positions,
2. The three-dimensional measuring method according to claim 1, wherein the correcting step corrects the three-dimensional coordinates of the measuring position using a temperature correction coefficient of a position closest to the measuring position. The correction coefficient acquisition step includes:
an interpolation step of interpolating the three-dimensional coordinates of the measured values at the plurality of positions at the measured temperature from the three-dimensional coordinates of the measured values at the plurality of temperatures of the reference measurement object;
a calculation step of calculating temperature correction coefficients for the plurality of positions at the measured temperature from the three-dimensional coordinates of the design values and the three-dimensional coordinates of the interpolated measured values;
The three-dimensional measurement method according to claim 2, comprising: In the interpolation step, one section including the measured temperature is determined among the plurality of temperature sections divided by the plurality of temperatures, and the three-dimensional coordinates and the lower limit temperature of the measured value at the upper limit temperature of the determined one section are determined. 4. The three-dimensional measuring method according to claim 3, wherein the three-dimensional coordinates of the measured values at the measured temperatures are linearly interpolated using the three-dimensional coordinates of the measured values at the temperature. a measurement sensor that acquires three-dimensional coordinates of the measurement position of the measurement object in mutually orthogonal three-axis directions;
a single temperature sensor for measuring the temperature of the measurement object;
Same shape and same material as the object to be measured a storage unit that stores a relationship between three-dimensional coordinates of design values of a plurality of positions of a reference measurement object and three-dimensional coordinates of actual measurement values obtained by measuring the plurality of positions of the reference measurement object at a plurality of temperatures;
a correction coefficient acquisition unit that reads out the stored relationship and acquires a temperature correction coefficient for each axial direction at the temperature measured by the temperature sensor;
a correction unit that corrects the three-dimensional coordinates of the measurement position using the acquired temperature correction coefficient;
3D measuring machine.

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