JP2021094600A - Machine tool and shape measurement method of workpiece machining part - Google Patents

Abstract

To enable the shape measurement of a workpiece machining part to be more accurately performed by eliminating a positional error in a measurement ball in an internal grinder.SOLUTION: A shape measurement method of a workpiece machining part comprises the steps of: preparing an internal grinder 1 including a main shaft 2 which is attached with a tool, a main shaft table 3 which supports the main shaft 2 in a movable manner, a workpiece chuck 4 which is attached with a workpiece W, a touch sensor 5 which is provided in the main shaft table 3, is moved by the main shaft table 3, and measures the shape of the workpiece W by being in contact with the workpiece W, and a camera 10 which images a contact point of the touch sensor 5; matching the imaging direction of the camera 10 with the axial direction of the touch sensor 5; imaging a measurement ball 5a and its periphery when the touch sensor 5 is in contact with the workpiece W; determining the positional error of the measurement ball 5a of the touch sensor 5 by using a signal from the touch sensor 5 and an image of the camera 10; and determining the shape of the workpiece W by using the positional error.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for measuring the shape of a machine tool such as an internal grinding machine and a lathe and a workpiece, and particularly to improving the shape measuring accuracy of the workpiece.

Conventionally, machine tools that measure the shape of a machined portion of a workpiece by using a touch sensor mounted on a spindle are known (for example, Patent Document 1 and Patent Document 2).

JP-A-2015-39732 Japanese Unexamined Patent Publication No. 2008-105134

However, in a machine having only two axes on a flat surface (for example, an inner grinding machine, a lathe, etc.), the shape of the workpiece can be measured by a touch sensor, but the obtained measurement result is a correct value. It is not always possible. This is because the coordinate 0 points on the work side and the measurement side are different due to thermal displacement, work chuck position error, and the like.

Specifically, if the measurement position of the work and the measurement position of the touch sensor tip measurement ball (also called stylus ball) deviate, measurement at the center of the work may not be possible, or the measurement position of the measurement ball itself may deviate. This causes a problem that a large measurement error occurs.

For example, as shown in FIG. 10, when the position of the measuring ball 105a of 0.1 mm is displaced in the Y direction, an error occurs in the measurement due to the change in the circumference on the work side. The error is, for example, 0.00167 mm.

In addition, the contact angle of the measuring ball 105a will be different. Since the outer diameter of the measuring ball 105a is considerably smaller than the inner diameter of the work W, this difference in contact angle occurs as a large error. When the outer diameter of the measuring ball 105a is 1 mm and the inner diameter of the work is 6 mm, the measured value of the measuring ball 105a is (X, Y) = (when the work center is (X, Y) = (0,0). In the case of 2.998, −0.128), the contact point of the measuring ball 105a is at a position where the contact angle is tilted by 2.3112 ° from the horizontal position, so the contact error is tan 2.3112 ° × 0. An error of 5 mm = 0.02018 mm occurs.

Further, regarding the influence of the difference between the contact point and the traveling direction, the traveling direction (X direction) of the measuring ball 105a is indicated by an arrow in FIG. When it is tilted by 2.3112 ° with respect to the traveling direction, the touch sensor detects when the operating pressing force of the measuring ball 105a is exceeded at the contact point with the tilted inner peripheral surface of the work. The amount of error differs depending on the magnitude of the working pressing force, but if the relationship between the component forces is grasped as a proportional relationship of 50% at 45 °, it will be detected with a force of 97.4%. 97.4% of the measuring ball 105a having a diameter of 1 mm occurs as an error of 0.0134 mm.

When these errors are added together, a total error of about 0.00167 + 0.0202 + 0.0134 = 0.0353 mm will occur at only one measurement point. If the outer diameter of the measuring ball 105a or the inner diameter of the work becomes smaller, there is a problem that this error increases.

The present invention has been made in view of this point, and an object of the present invention is to remove a position error in a measuring ball in consideration of the above-mentioned error generation mode to perform more accurate shape measurement of a workpiece. To be able to do it.

In order to achieve the above object, in the present invention, the position error of the measuring sphere is grasped by adding the data by the image and the laser beam.

Specifically, the machine tool of the first invention is
The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
An imaging means for imaging the contact point of the touch sensor and the vicinity of the contact point, and
A control unit is provided that uses a signal from the touch sensor and an image obtained by the imaging means to determine a position error of a measurement ball of the touch sensor, and uses the position error to determine the shape of the work. ing.

According to the above configuration, not only the measurement result of the touch sensor but also the image by the imaging means is acquired together, so that the position error of the measurement ball of the touch sensor can be appropriately corrected and the shape of the workpiece can be measured more accurately. Become.

In the second invention, in the first invention,
The imaging means is a camera provided on or near the main body of the touch sensor, and is configured to image the measuring sphere and the periphery of the measuring sphere when the touch sensor comes into contact with the work. ing.

According to the above configuration, the position error of the measuring ball can be reliably corrected by the camera provided in or near the main body of the touch sensor, so that the measurement accuracy of the touch sensor is improved.

In the third invention, in the second invention,
Since the touch sensor and the spindle are provided on the same plane, the processing point of the spindle and the measurement point by the touch sensor are kept the same.

According to the above configuration, the machining point and the measurement point are kept the same, so that the reliability is improved.

In the fourth invention, in the second or third invention,
The imaging direction of the camera coincides with the axial direction of the touch sensor.

According to the above configuration, an error does not occur as in the case where the image pickup direction of the camera and the axial direction of the touch sensor are deviated and tilted, and a more accurate workpiece shape can be measured.

In the fifth invention, in the first invention,
The imaging means is a quantified measuring device, and a position error can be calculated using the position information measured from the quantified measuring device.

According to the above configuration, the position error can be calculated using the position information measured from a numerical measurement device such as a laser, for example, a radar irradiation measurement device, so that the error can be easily eliminated and the reliability is improved.

In the sixth invention, in any one of the first to fifth inventions,
It is an internal grinding machine,
The control unit is configured to correct the inner diameter value of the work measured by the touch sensor by utilizing the position error.

According to the above configuration, even on the inner surface of the work by the inner surface grinding machine that can move only two axes on the same plane, the inner surface is accurately ground by using the measured value of the touch sensor.

In the seventh invention,
The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
The laser unit that detects the position of the contact point of the touch sensor and
The signal from the touch sensor and the rotation angle by the encoder when the laser unit is rotated are used to determine the position error of the measurement ball of the touch sensor, and the position error is used to determine the shape of the work. It is provided with a control unit for determining.

According to the above configuration, the position error of the measurement ball of the touch sensor can be corrected by using the rotation angle obtained from the encoder of the laser unit, so that the shape of the workpiece can be measured more accurately.

In the method for measuring the shape of the workpiece according to the eighth aspect of the invention,
The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
A machine tool having a contact point of the touch sensor and a camera that images the periphery of the contact point is prepared.
Match the imaging direction of the camera with the axial direction of the touch sensor,
When the touch sensor comes into contact with the work, the measuring sphere and the periphery of the measuring sphere are imaged.
The signal from the touch sensor and the image taken by the camera are used to determine the position error of the measurement ball of the touch sensor, and the position error is used to determine the shape of the work.

According to the above configuration, not only the measurement result of the touch sensor but also the image taken by the camera is acquired together, so that the position error of the measurement ball of the touch sensor can be appropriately corrected, and the shape of the workpiece can be measured more accurately. ..

In the ninth invention, in the eighth invention,
A work side reference line is provided on the work chuck side, and the work side reference line is provided.
The touch sensor is moved horizontally within the imaging range of the camera to create a movement line on the sensor side.
The inclination of the work is detected by comparing the movement line on the sensor side with the reference line on the work side.
After correcting the position error using the inclination of the work, the shape of the work is measured.

According to the above configuration, the inclination of the work is detected by comparing the movement line on the sensor side and the reference line on the work side, and the position error due to the inclination can be corrected at the time of measurement by the touch sensor, so that the shape of the work is more accurate. Measurement becomes possible.

As described above, according to the present invention, it is possible to more accurately measure the shape of the workpiece by removing the position error in the measuring sphere from the additional information obtained by the imaging means (camera) or the laser beam.

It is a front view which shows the inner surface grinding machine including a camera and a touch sensor. It is a top view which shows the inner surface grinding machine including a camera and a touch sensor. It is a schematic diagram for demonstrating the positional relationship between the image acquisition range by a camera and a work. It is a top view for demonstrating the positional relationship between a camera, a touch sensor, and a work. (A) The relationship between the horizontal line of the work and the moving direction of the measuring sphere when there is no thermal deformation is shown, and (b) the inclination of the horizontal line of the work and the moving direction of the measuring sphere when the thermal deformation occurs. is there. It is a schematic diagram for demonstrating the positional relationship between the image acquisition range by a camera and a work. It is a schematic diagram for demonstrating the positional relationship between a work and a measurement point when a work is tilted by 1 °. It is a schematic diagram for demonstrating the contact angle of the measuring sphere which concerns on the modification of embodiment. It is a table which shows the relationship between the contact angle and the amount of deviation in the Y direction. It is a schematic diagram which shows the relationship between the work inner peripheral surface and a measuring ball when it deviates in the Y direction. It is a schematic diagram for demonstrating the influence by the difference between a contact point and a traveling direction. It is a schematic diagram for demonstrating the measurement example in the case where there is no deviation in the height direction of the work using a laser. It is a schematic diagram for demonstrating the measurement example in the case where there is a deviation in the height direction of the work using a laser. It is a graph which shows the relationship between the measurement result of a machined inner diameter of 10 mm, and the amount of deviation in a height direction. It is a top view which shows the outline of the apparatus structure when the laser part is supported on the Y axis. The outline of the apparatus configuration when the laser part is supported on the Y axis is shown, (a) is a front view, and (b) is a side view.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 show a main part of an inner surface grinding machine 1 as a machine tool according to an embodiment of the present invention, and the inner surface grinding machine 1 includes a spindle 2 to which a tool such as a grindstone is attached. The spindle 2 can be rotated at an arbitrary speed by the spindle motor 2a, and is supported by a spindle table (spindle column) 3 so as to be movable in the Z-axis direction. A work chuck 4 to which the work W is attached is provided at a position facing the spindle table 3. The work chuck 4 is provided on a work table (not shown) so as to movably support the work W in the X and Y directions. The basic structure of the inner surface grinding machine 1 is the same as the known structure.

A touch sensor 5 is provided on the spindle table 3. The touch sensor 5 is provided at the tip of a touch sensor arm 6 swingably supported by the spindle table 3, for example, and has a measurement position arranged in front of the spindle 2 when measuring the shape of the work W. It can swing between the standby position and the standby position, which is swiveled by about 90 ° with respect to this measurement position. The touch sensor arm 6 rotates the arm motor 6a at the base thereof, so that the touch sensor 5 extends in the Z-axis direction in the measurement posture arranged in front of the main shaft 2. The touch sensor 5 has a measuring ball 5a at the tip of the rod-shaped member, is moved in the Z-axis direction by the spindle table 3, and the measuring ball 5a comes into contact with the work W to measure the shape of the work W. Has been done. The measuring sphere 5a is, for example, a sphere having an outer diameter of 1 mm. A columnar touch sensor main body 5b is provided on the root side of the touch sensor 5, and the measured value is transmitted to the control panel 7 or the like as the control unit of the inner surface grinding machine 1 via the harness 5c for the touch sensor. It has become. Since the touch sensor 5 extends in the Z-axis direction, it is provided on the same plane as the main shaft 2. In other words, the processing point of the spindle 2 and the measurement point by the touch sensor 5 are kept the same.

The inner surface grinding machine 1 of the present embodiment includes a camera 10 as an imaging means for imaging the contact point of the measuring ball 5a of the touch sensor 5 and its periphery. The camera 10 is provided, for example, in the touch sensor main body 5b, for example, on the right side of the measuring ball 5a. The imaging direction of the camera 10 coincides with (parallel to) the axial direction of the touch sensor 5, that is, the axial direction of the Z axis.

As will be described in detail later, the control panel 7 uses the signal from the touch sensor 5 and the image taken by the camera 10 to determine the position error of the measurement ball 5a of the touch sensor 5, and uses this position error to determine the position error of the work W. It is programmed to determine the shape of (for example, the inner diameter value of the work W).

-Operation of internal grinding machine-
Next, the operation of the inner surface grinding machine 1 according to the present embodiment will be described.

First, the above-mentioned internal grinding machine 1 is prepared.

Next, the touch sensor arm 6 is swung to move it to a measurement position in front of the spindle 2. At this time, the imaging direction of the camera 10 is made to coincide with (parallelize) the axial direction (Z-axis direction) of the touch sensor 5. Moreover, when viewed from the Z-axis direction, as shown in FIG. 1, the height of the measurement ball 5a of the touch sensor 5 and the height of the camera in the imaging direction coincide with each other. If there is a difference in height, the image data will be tilted, and if the position in the Z direction deviates, a measurement error will occur, but it is necessary to avoid that measurement error. In the present embodiment, the machining point by the spindle 2 and the measurement point by the touch sensor 5 are kept the same, so that the reliability is improved.

Next, the spindle table 3 is advanced in the Z-axis direction, and the measuring ball 5a of the touch sensor 5 is brought into contact with the work W. When measuring the inner diameter of the work W, the work W side is moved in the X-axis direction. When the measuring ball 5a comes into contact with the inner surface of the work W, the base is bent and a predetermined torque or more is applied, the touch sensor 5 is turned on. The position coordinates of X and Y at that time are recorded on the control panel 7. When the touch sensor 5 is turned on, the camera 10 takes an image of the measuring ball 5a and its surroundings.

The control panel 7 uses the signal from the touch sensor 5 and the image taken by the camera 10 to determine the position error of the measurement ball 5a of the touch sensor 5, and uses the position error to determine the shape of the work W. To do.

As shown in FIGS. 3 and 4, the Y-direction height of the camera 10 is kept the same as the Y-direction height of the measurement ball 5a in order to avoid measurement error, and the camera 10 is shown in FIG. 3 of the touch sensor main body 5b. When fixed to the right side, the captured image is the shadow of the touch probe including the measurement ball 5a on the left side, so only the measurement ball 5a of the work W and the right side part of the work W (in FIG. 3, a thick rectangular line). It becomes the surrounding area B).

Here, it is not possible to determine the deviation from the posture of the work W due to thermal deformation in the inner surface grinding machine 1 (parallel failure with the moving line M in the X direction on the camera 10 side) only from the image captured by the camera 10.

That is, as shown in FIG. 5A, if the work W is not displaced due to thermal deformation or the like, the center line C in the X direction is the same straight line as the moving line M in the X direction of the measuring sphere 5a. There is no problem. On the other hand, as shown in FIG. 5B, when thermal deformation occurs, the sensor-side movement line M (indicated by a broken line) in the X direction of the measuring ball 5a and the center line C (indicated by a dashed line) on the work W side. The parallelism with and is impaired, but this cannot be grasped from the image on the right side only. It is conceivable to attach a camera 10 that captures the left side, but it cannot be confirmed that the two cameras 10 on the left and right have the same inclination. Also, if you take the whole picture from the bottom, it will be tilted, which is a problem.

Therefore, the work W side reference line S is provided within the imaging range on the right side. Specifically, as shown in FIG. 6, the work chuck 4 is stopped at a fixed position, and a work W side reference line S is created in the chuck portion 4a (shown by a thick line in FIG. 6). Although not shown, for example, the work W side reference line S is created forward from the outside of the work chuck 4 via the bracket.

-Camera images and their processing-
Next, the image captured by the camera 10 and the handling process thereof will be described.

As shown in FIG. 6, the position of the contact point of the measuring ball 5a can be grasped from the captured image. In addition, the maximum diameter of the work W can be recognized. From the position information of this maximum diameter part, it is possible to measure how much the measurement point has deviated.

On the other hand, due to the position of the camera 10, it is difficult to analyze the left image as described above. Therefore, the work W side reference line S as described above is provided on the work chuck 4.

If the work W side reference line S is taken in, the inclination of the work W can be easily grasped from the comparison with the work W side reference line S. For example, an image of the work W side reference line S is captured before the operation of the inner surface grinding machine 1, and the inclination of the work W side reference line S is set to 0 and compared with the sensor side moving line M, respectively. The inclination at the time of measurement is obtained.

Next, the method of correction will be described. For example, when a hole having an inner diameter of 12 mm is machined in the work W, when the center of the work W is X = 0 and the inner surface contact point is X = 6, the radius of 0.5 mm of the measuring ball 5a is added at the time of coordinate acquisition.

Here, it is assumed that the measurement position is X = 5.8 mm and the inclination is 1 ° at a point 0.1 mm away from the center.

Normally, when the measured values are X = 5.8 (X = 0 is the center of the work W) and X = 5.798, in order to obtain the target value (X = 6), the target value is expanded to 0.206. Correction is required. Here, since the difference between the left and right points is recognition as a thermal displacement somewhere, only the error amount value can be seen.

On the other hand, in the image method of the present application, when the work W is tilted by 1 ° as an error due to the work W on the right side, the measurement point is at the position shown in FIG. This is an error that occurs because the thermal deformation differs between the work W side and the measurement side. Located Y = 0.1 mm measurement point under the maximum diameter portion, when the measurement value becomes X = 5.8 mm, measuring the position error of the workpiece W is, √ ^{(5.8 2} -0.1 ²⁾ = 5.7991 mm. This is about 1 μm smaller than the actual measured value.

On the other hand, as the contact point error of the measuring ball 5a on the right side, X ² + Y ² = 5.8 ^{2 for the work W and (X-5.3) 2} + (Y- (-0.1) for the measuring ball 5a. ) From ² = 0.5 ² (using the measured value), the intersection of the two circles is the point of X = 5.8 mm and Y = 0.076 mm. In the measurement sphere 5a, Y = 0.076 only lowered the point of contact points, to the radius of the measuring ball 5a, the ^{√ (0.5 2 -0.076 2) =} 0.494 2. The measurement position is a point about 6 μm past the radius R = 0.5. This indicates the amount of deviation of the contact point of the measurement point in the X direction.

Since the measurement point on the left side, which does not appear in the image, is 1 ° lower, it is further below the maximum diameter on the right side by Y = 0.1 mm, and further sin1 ° × (ABS (-5.798) +5. Since the tilt of 8) is downward in the Y direction, the left side is measured downward by Y = 0.202 mm.

As an error by the left of the workpiece W, the measurement position error, becomes ^{√ (-5.798 2 -0.202 2) =} 5.7944, approximately 6μm smaller than the measured value.

Further, as the contact point measurement error balls 5a (left measurement) and similarly to the right processing determining an intersection of two circles on the left, the workpiece ^W, the X ² + ^Y 2 = 5.792 2 measuring balls 5a, (X -5.2922) From ² + (Y- (-0.202)) ² = 0.5 ² , the intersections are X = 5.792 and Y = 0.156.

It becomes contact 0.5 ² -0.156 ² = 0.475, will have been measured at a point only approximately 15μm relative radius R = 0.5. This indicates the amount of deviation of the contact point of the measuring ball 5a in the X direction.

When these left and right errors are added up, the measured value is increased by 1 μm + 6 μm + 6 μm + 15 μm = 28 μm. That is, a correction of −28μ is required as compared with the normal measurement value correction.

That is, the normal correction value is 0.206 mm, and the image usage correction amount has a difference of 0.206 mm-0.028 mm = 0.178 mm.

Further, as an error, a push force error due to the contact angle occurs, and the amount of this error is proportional to the angle. Since the amount of contact angle error differs depending on the touch sensor 5 used, it is necessary to determine the correction amount depending on the touch sensor 5 actually used. The push pressure error tends to delay the reaction.

The measurement start point is accurate because it is evaluated relative to the image. When the starting points are aligned, tilt correction is also effective.

In order to improve this point, the parallel work W side reference line S is inserted into the camera 10 to grasp the inclination. In this embodiment, the work W side reference line S is provided parallel to the chuck portion 4a.

The work W side reference line S is taken in, and the inclination can be easily grasped from the comparison between the work W side reference line S and the sensor side moving line M. The work W side reference line S captures an image before the machine is operated, sets the inclination of the work W side reference line S to 0, and compares it with the sensor side moving line M to obtain the inclination at the time of each measurement. You can ask for it. After correcting using the inclination of the work W, the shape of the work W is measured.

In the present embodiment, not only the measurement result of the touch sensor 5 but also the image taken by the camera 10 is acquired together, so that the more accurate shape of the work W can be measured by utilizing the position error of the measurement ball 5a of the touch sensor 5. It becomes.

Therefore, according to the inner surface grinding machine 1 according to the present embodiment, the position error in the measuring ball 5a can be removed to more accurately measure the shape of the machined portion of the work W.

-Modification example-
8 and 9 show a modification of the embodiment of the present invention, which is different from the above embodiment in that the camera 10 is not provided. In each of the following modifications, the same parts as those in FIGS. 1 to 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above embodiment, the camera 10 is provided as an imaging means, but instead of the camera 10, a laser unit 110 as a numerical measurement device for detecting the position of the contact point of the touch sensor 5 may be provided. The laser unit 110 may be configured by providing a laser head at the mounting position of the camera 10, and the contact angle at which the measurement sphere 5a is deviated from the center line in the X direction of the work W by transmitting and receiving laser light from a radar irradiation measuring device or the like. The configuration is not limited as long as θ can be detected.

In this case, the control panel 7 uses the signal from the touch sensor 5 and the rotation angle (contact angle θ) by the encoder when the laser unit 110 is rotated to determine the position error of the measurement ball 5a of the touch sensor 5. judge. Since the position error measured by the laser unit 110 can be used, the reliability is improved.

For example, as shown in FIG. 8, the relationship between the contact angle θ and the amount of deviation in the Y direction is detected by the X and Y coordinates of the contact point between the inner surface of the work W having the inner diameter of the measuring sphere 6 mm and the measuring sphere 5a, and the laser unit 110. When combined with the value of the contact angle θ, the value A of the deviation in the Y direction can be found.

As a correction method, when the outer diameter of the measuring ball 5a is 1 mm, the contact position of tan (A) × 0.5 mm = X axis is obtained from the X-axis position and the contact angle θ. The measured value of the X-axis is calculated from the measurement position of the X-axis + the contact position of the X-axis. Further, the amount of deviation of the Y-axis can be obtained from the contact angle θ using FIG. From there, the measured value on the Y axis is calculated. Then, the current inner diameter is obtained from the square root of the X-axis value + the square root of the Y-axis value, and the amount until reaching a predetermined value is accurately obtained.

The shape of the work W may be determined using this position correction.

When having a swivel mechanism, the work-side spindle unit may have a mechanism for levitating the entire unit by 1 mm. In this case, the swivel operation is performed in the levitated state. It is preferable to obtain the amount of deviation of the work W and the grindstone 111 (laser unit 110) in the height direction and the direction thereof by performing a measurement using this amount of levitation.

FIG. 12 shows a measurement example when there is no deviation in the height direction of the work W. When machining a hole with an inner diameter of 10 mm, the deviation in the height direction with a radius of 5.0 mm is 5.0 mm at the lower end of the swivel and 4.899 mm at the upper end of the swivel.

As shown in FIG. 13, when the work W (machined hole) height direction deviates upward with respect to the laser unit 110, when the swivel rises, the swivel rise amount of 1 mm is added to the lower circle of the machined hole. Measure the side (shown by a thick dashed line in FIG. 13). When the height of the work W is shifted upward by 0.2 mm, it is 4.996 mm at the lower end of the swivel and 4.854 mm at the upper end of the swivel.

When the work W (machined hole) height direction deviates downward with respect to the laser measuring instrument, when the swivel rises, the swivel rise amount is 1 mm minus the work W height shift amount. The lower side is measured (shown by a thin dashed line in FIG. 13). An example of measurement when the height of the work is shifted downward by 0.2 mm is shown. When machining a hole with an inner diameter of 10 mm, the deviation in the height direction with a radius of 5.0 mm is 4.996 mm at the lower end of the swivel and 4.800 mm at the upper end of the swivel.

FIG. 14 shows the result of measuring the deviation between the lower end of the swivel and the upper end of the swivel when the deviation in the height direction is changed.

By measuring the point where the swivel is raised, there is a difference in the measurement result, and by grasping this amount, it is possible to grasp the amount of deviation.

At the lower end of the swivel raising mechanism, the direction of deviation cannot be specified due to the direction of deviation in the height direction, and the same value occurs (diamond in FIG. 14).

At the upper end of the swivel raising mechanism, there is a difference from the measured value at the lower end depending on the deviation direction in the height direction, so it can be seen that the deviation direction can be specified from the difference amount (square in FIG. 14).

Next, a specific operation of the internal grinding machine 1 will be described. A cylindrical work W is gripped by the work chuck 4, and a laser unit 110 is provided in a portion of the camera 10. Since the shape of the work W is cylindrical, the laser unit 110 is driven from the time when the laser light passes to the time when it is blocked.

At the lower end of the swivel, laser irradiation in the hole is performed, it moves along the X axis, and the data of the machine stop and stop position is stored by the laser cutoff. In-hole laser irradiation is also performed at the upper end of the swivel, it moves along the X-axis, the machine is stopped by laser interruption, and the data of the stop position is stored. From the X coordinate position, the point corresponding to the graph of FIG. 14 is read and the correction amount is calculated.

As illustrated in FIGS. 15 and 16, a Y-axis mechanism 108 may be added, and the laser unit 110 may be supported on the Y-axis for measurement. The inner surface grinder 101 has an X-axis saddle 109, a Y-axis mechanism 108, a grindstone 111, and the like, and a laser portion 110 is supported by the Y-axis mechanism 108. A cylindrical work W is gripped by the work chuck 104. The layout may be based on the positional relationship between the work chuck 104 and the laser unit 110, the X-axis, and the Z-axis. In this case as well, the machined hole diameter can be derived by operating the Y-axis and the X-axis.

(Other embodiments)
The present invention may have the following configuration with respect to the above embodiment.

That is, in the above embodiment, the example of the internal grinding machine 1 is shown as a machine tool, but the present invention is not limited to this, and other machine tools such as a lathe having only two axes in a plane may be used.

It should be noted that the above embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its applications and applications.

1 Internal grinding machine (machine tool)
2 spindle
2a Spindle motor
3 spindle table
4 Work chuck
5 Touch sensor
5a measuring ball
5b Touch sensor body
5c Touch sensor harness
6 Touch sensor arm
6a arm motor
7 Control panel
10 Camera (imaging means)
101 Internal grinder
104 Work chuck
108 Y-axis mechanism
109 X-axis saddle
110 laser section
111 whetstone

Claims (9)

The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
An imaging means for imaging the contact point of the touch sensor and the vicinity of the contact point, and
A control unit is provided that uses a signal from the touch sensor and an image obtained by the imaging means to determine a position error of a measurement ball of the touch sensor, and uses the position error to determine the shape of the work. A machine tool characterized by being In the machine tool according to claim 1,
The imaging means is a camera provided on or near the main body of the touch sensor, and is configured to image the measuring sphere and the periphery of the measuring sphere when the touch sensor comes into contact with the work. A machine tool characterized by being In the machine tool according to claim 2.
A machine tool characterized in that the processing point of the spindle and the measurement point by the touch sensor are kept the same by providing the touch sensor and the spindle on the same plane. In the machine tool according to claim 2 or 3,
A machine tool characterized in that the imaging direction of the camera coincides with the axial direction of the touch sensor. In the machine tool according to claim 1,
The imaging means is a quantified measuring device, and is a machine tool characterized in that a position error can be calculated using the position information measured from the quantified measuring device. In the machine tool according to any one of claims 1 to 5,
It is an internal grinding machine,
The machine tool is characterized in that the control unit is configured to correct the inner diameter value of the work measured by the touch sensor by utilizing the position error. The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
The laser unit that detects the position of the contact point of the touch sensor and
The signal from the touch sensor and the rotation angle by the encoder when the laser unit is rotated are used to determine the position error of the measurement ball of the touch sensor, and the position error is used to determine the shape of the work. A machine tool characterized by having a control unit for determining. The spindle to which the tool is attached and
A spindle table that movably supports the spindle and
The work chuck to which the work is attached and
A touch sensor provided on the spindle table, moved by the spindle table, and a measuring ball at the tip comes into contact with the work to measure the shape of the work.
A machine tool having a contact point of the touch sensor and a camera that images the periphery of the contact point is prepared.
Match the imaging direction of the camera with the axial direction of the touch sensor,
When the touch sensor comes into contact with the work, the measuring sphere and the periphery of the measuring sphere are imaged.
A work characterized by using a signal from the touch sensor and an image taken by the camera to determine a position error of a measurement ball of the touch sensor, and using the position error to determine the shape of the work. Method of measuring the shape of the machined part. In the method for measuring the shape of a workpiece according to claim 8,
A work side reference line is provided on the work chuck side, and the work side reference line is provided.
The touch sensor is moved horizontally within the imaging range of the camera to create a movement line on the sensor side.
The inclination of the work is detected by comparing the movement line on the sensor side with the reference line on the work side.
A method for measuring the shape of a workpiece, which comprises measuring the shape of the workpiece after correcting it using the inclination of the workpiece.

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