JP2825429B2 - Measurement method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method and a measuring apparatus for measuring the shape and dimension of an object having a three-dimensional shape in a three-dimensional coordinate system, and more particularly to a single displacement detecting type measuring head. When the shape is measured by calculating from the read data of the surface coordinate value of the measured object, and when the measuring element of the same displacement detection type measuring head comes into contact with the measured object and is displaced, By calculating coordinate values and calculating according to a predetermined mathematical formula from the obtained values, various dimensions such as a diameter dimension and a hole position dimension of a hole formed in the object to be measured or a width dimension of a part to be processed are measured. The present invention relates to a measuring method and an apparatus which can be used for automatically performing a measurement by classifying the measurement into a method.

[0002]

2. Description of the Related Art A measuring head is provided with a measuring element (feeler) having a spherical shape at its tip, and detects displacement data in the X, Y, and Z-axis directions when the measuring element contacts an object to be measured. A displacement detection type measuring head capable of performing the measurement has already been widely used. As a measuring method using such a displacement detecting type measuring head, there is known a method disclosed in Japanese Patent Publication No. 53-393.
The tip sphere of the tracing stylus is relatively displaced by pressing and contacting to the position to be measured on the surface of the object to be measured, which is disclosed in Japanese Patent Application Laid-Open No. 5-205, and the sphere radius R in that case and the X, Y, Z axes Of the displacements I, J, K generated in each axial direction (E =
Ｘ (I ² + J ² + K ² ), that is, the square root of (I ² + J ² + K ² )), the X, Y,
There is a method in which the reading of the Z-axis coordinate is regarded as the coordinate of the measurement point.

Further, a known method disclosed in Japanese Patent Publication No. 58-4962 discloses a method for obtaining a coordinate value of a point offset outward by a distance F from a point on the surface of the object. In the process of relative movement between the measuring head and the measuring head, the tip spherical portion of the measuring element of the displacement detecting type measuring head is pressed against a point on the surface of the object to be measured, and the radius R of the spherical portion and the X, Y,
The resultant displacement (E = √ (I ² + J ² + K ² )) of the displacement amounts I, J, K in the respective Z-axis directions, ie, (I ² + J ² +
K ² ) is equal to the square root of E 2.
₀ , and X,
The reading of the Y and Z axis coordinates is measured as the coordinates of a certain point on the surface of the object to be measured, and the coordinates of the point offset therefrom by the above-described offset amount F are (X + FI / E ₀ , Y +
F · J / E ₀ , Z + K / E ₀ ). In other words, in both of the known methods described above, the probe is pressed against the DUT by a feedback control method such that the combined displacement of the tip ball of the probe of the displacement detection type measurement head is always equal to the radius of the ball. There was a restriction that we had to do it.

[0004]

As a result, it takes a long time to calculate the resultant displacement. Therefore, unless the feed speed in the relative movement between the workpiece and the measuring head is reduced, the tracing stylus is moved at an accurate position to the workpiece. There is a problem that it cannot be positioned at desired points on the surface. In particular, when the relative movement between the object to be measured and the measuring head is automatically performed under the control of an NC device or the like, the time required to execute the calculation of the resultant displacement is limited, and the movement of the object to be measured naturally occurs. There is also a problem that the measurement can be performed only at a plurality of spaced positions.

If the relative feed speed in the relative movement between the object to be measured and the measuring head is high, positioning cannot be performed at a point where the radius R of the ball of the tracing stylus and the resultant displacement E ₀ are equal. There is also a problem that a measurement error increases.

Accordingly, in view of the above-mentioned problems, an object of the present invention is to measure the object to be measured using a displacement detection type measuring head, in which the radius of the spherical portion at the tip of the tracing stylus coincides with the resultant displacement. Without this, the coordinate value of the position to be measured can be measured accurately and efficiently, and the relative movement in the X, Y, and Z-axis directions between the object having a three-dimensional shape and the displacement detection type measurement head. When the contact point of the measuring head is brought into contact with the DUT and the coordinate value of the contact point or the position offset from the surface of the DUT is measured, the radius value of the measuring element sphere is simply known data. It is intended to provide a measuring method and a device capable of executing a measurement by using the same in arithmetic processing.

[0007]

DISCLOSURE OF THE INVENTION In view of the above-mentioned object, the present invention provides a measuring head having a X, a three-dimensional coordinate system.
Displacement detecting means capable of detecting the displacement generated in the Y and Z axis directions, and a displacement detection type measuring head having a measuring element displaceable in the X, Y and Z axis directions, and The measuring element of the measuring head is pressed against and brought into contact with the surface of the object to be measured by relative movement with the same displacement detecting type measuring head. At this time, displacements in the respective axial directions generated on the measuring element are detected by displacement detecting means. From the detected data, an operation is performed in accordance with a predetermined arithmetic expression to obtain a combined displacement amount, and the measured value is calculated from the calculated value of the combined displacement amount and the radius data of the ball portion of the tracing stylus which is recognized in advance as a known amount. Some of the coordinate values of the contact point between the object and the tracing stylus or the coordinate value of the position offset from the contact point by a predetermined offset amount are calculated and obtained as required.

That is, according to the present invention, relative movement in the X, Y, and Z-axis directions is performed between the measurement object having a three-dimensional shape and the measurement head, and the measurement element of the measurement head is moved to the measurement object. In a measuring method for measuring the coordinate value of a position offset from the contact point and the surface of the workpiece by contacting,
The measuring head includes a tracing stylus having a spherical portion at a tip and supported to be displaced in a substantially normal direction with respect to the surface of the object to be measured when the measuring head comes into contact with the surface of the measuring object.
Using a displacement detection type measuring head capable of detecting each displacement in the Z-axis direction, the item to be measured needs to be in the first measurement mode which requires a step of obtaining coordinates of the surface of the object to be measured, or the surface of the object to be measured It is determined whether the second measurement mode requires a step of obtaining coordinates of a point offset by a predetermined amount from the first measurement mode. For the measurement items determined as the first measurement mode, the X, Y, and Z axes of the displacement detection type measurement head are determined. Each position data in the direction is read, and the coordinate value (U, V, W) of the contact point when the tracing stylus of the displacement detection type measuring head is brought into contact with the surface of the object to be measured is expressed by U = X− ( R−E) · I / E (1) V = Y− (RE) · J / E (2) W = Z− ( R−E) · K / E (3) In this case, R is a known value of the radius of the tip sphere of the tracing stylus. ,
I, J, K are X, Y,
Each displacement, E, in the Z-axis direction is a combined displacement of the tracing stylus, and E = √
(I ² + J ² + K ² ), that is, the value of E is (I ² + J ²
X, Y and Z, which are equal to the square root of + K ² ), are obtained according to the equations (1) to (3) expressed by the respective position data of the displacement detection type measuring head when the displacement is detected by contact. For the measurement item determined as the second measurement mode, the position data of the displacement detection type measurement head in the X, Y, and Z-axis directions is read, and the measuring element of the displacement detection type measurement head is placed on the surface of the workpiece. The coordinate value (x, y, z) at a position offset by a predetermined amount from the contact point at the time of contact is represented by: x = X + (E−E ₀ ) · I / E (4) y = Y + (E−E ₀ ) · J / E (5) z = Z + (E−E ₀ ) · K / E (6) In this case, E ₀ is a reference displacement amount set in advance, an amount of the radius R of the end ball portion of the probe by subtracting the predetermined offset amount r _0, I, J, K displacement test X detected in the form measuring head, Y, the displacement in the Z-axis direction, E is E = √ synthetic displacement of the measuring element ^{(I 2 + J 2 + K} 2), i.e. the value of E is (I ² +
X, Y, and Z, which are equal to the square root of J ² + K ² ), are obtained according to the equations (4) to (6) of each position data of the displacement detection type measuring head when the displacement is detected by contact. A measurement method is provided.

Further, according to the present invention, relative movement in the X, Y, and Z-axis directions is performed between the measurement object having a three-dimensional shape and the measurement head, and the measurement element of the measurement head is attached to the measurement object. In a measuring device that measures coordinate values and dimensions by contacting
The measuring head includes a tracing stylus having a spherical portion at the tip and supported so as to be displaced in a substantially normal direction with respect to the surface of the measuring object when it comes into contact with the surface of the measuring object. , Z
Position reading means formed as a displacement detection type measurement head capable of detecting each displacement in the axial direction, reading position data of the displacement detection type measurement head in the X, Y, and Z directions; The coordinate value (U, V, W) of the contact point when the probe of the displacement detection type measurement head is brought into contact is expressed as follows: U = X− (RE) · I / E .. (1) V = Y− (RE) · J / E (2) W = Z− (RE) · K / E・ ・ (3) where R is a known value of the radius of the tip sphere of the tracing stylus.
J and K are the displacements in the X, Y and Z-axis directions detected by the displacement detection type measuring head, and E is the combined displacement of the tracing stylus, and E = √ (I
² + J ² + K ² ), that is, the value of E is (I ² + J ² + K
² ) X, Y, and Z, which are equal to the square root of, are each position data of the displacement detection type measuring head when contact is detected and displacement is detected;
Surface coordinate calculating means obtained according to the equations (1) to (3), and coordinates of a position offset by a predetermined amount from the contact point when the measuring element of the displacement detection type measuring head is brought into contact with the surface of the object to be measured. The value (x, y, z) is expressed as follows: x = X + (E−E ₀ ) · I / E (4) y = Y + (E−E ₀ ) · J / E .. (5) z = Z + (E−E ₀ ) · K / E (6) where E ₀ is a preset reference displacement amount, and The amount obtained by subtracting a predetermined offset amount r ₀ from the radius R, I, J, and K are X, X detected by the displacement detection type measuring head.
Each displacement in the Y and Z axis directions, E is the combined displacement of the tracing stylus and E =
√ (I ² + J ² + K ² ), that is, the value of E is (I ² + J ²
X, Y, and Z, which are equal to the square root of + K ² ) are offset coordinate calculation means obtained according to equations (4) to (6) of each position data of the displacement detection type measuring head when contact is detected and displacement. An NC device for controlling the relative movement of the object to be measured and the displacement detection type measurement head in the X, Y, and Z-axis directions, and a step of determining the surface coordinates of the object to be measured requires an item to be measured. Measuring mode determining means for determining whether the measurement mode is the first measuring mode or the second measuring mode which requires a step of obtaining coordinates of a point offset by a predetermined amount from the surface of the device under test; For the determined measurement item, a measurement value is obtained using the output of the surface coordinate calculation means, and for the measurement item determined to be in the second measurement mode by the determination means, measurement is performed using the output of the offset coordinate calculation means. Comprising a measurement value calculating means for obtaining a measurement device is provided.

[0010]

According to the above construction, the arithmetic expressions (1) to (6)
By making full use of, it is possible to measure the shape by measuring the surface coordinate value of the three-dimensional object to be measured, or to measure the dimension by obtaining the coordinate value of the measurement center of the measuring element by offset calculation. Further, when the measurement target is a shape measurement and a dimension measurement, the two measurement modes are set as two measurement modes. Can be sequentially executed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 shows a state in which a tracing stylus supported so as to be displaced in a substantially normal direction with respect to the same surface of a displacement detection type measuring head is pressed against the surface of an object to be measured having a three-dimensional shape in a three-dimensional coordinate system. FIG. 2 is a principle diagram for measuring coordinate values of a contact point, and FIG. 2 shows a distance r in the normal direction from the contact point when the measuring element of the displacement detection type measuring head is pressed against the surface of the object having the same three-dimensional shape. FIG. 3 is a principle diagram for measuring a coordinate value of a point S (usually a point inside a spherical tracing stylus) offset by ₀ , and FIG. 3 controls a relative movement between an object to be measured and a displacement detection type measuring head. While measuring the coordinate value of the contact point or the coordinate value of the offset point S of the object to be measured from the same displacement detection type measuring head according to the principle shown in FIG. 1 or FIG. Of measurement equipment that enables automatic measurement of FIG. 4 is a block diagram showing the configuration, FIG. 4 is a diagram schematically showing the relationship between a measurement point and a probe when measuring the coordinate value of a certain point on the surface of the object to be measured in a two-dimensional coordinate system, and FIG. FIG. 6 is a schematic diagram illustrating a measurement method for determining an intersection between two straight lines on the surface of the object to be measured and an angle formed by the two straight lines at the same intersection.
FIG. 7 is a schematic diagram for explaining a method of measuring a distance between two surfaces of an object to be measured by replacing the distance with two straight lines in a two-dimensional coordinate system. FIG. 8 is a schematic explanatory view illustrating an arc measurement applicable to the radius measurement of a spherical surface of an object in a two-dimensional coordinate system. FIG. 8 shows a measurement applied to a measurement of a pitch dimension of a large number of holes formed in an object to be measured. FIG. 9 is a schematic diagram for simplifying and explaining the method in a two-dimensional coordinate system.
FIG. 3 is a schematic diagram for describing, in a two-dimensional coordinate system, a measurement method when applied to a distance measurement between a center of a circular hole formed in a measured object and another surface of the measured object.

Referring to FIG. 1, a spherical measuring element 14 (radius R) supported via a support shaft 12 to a displacement detecting type measuring head 10 not shown or shown is attached to a workpiece W.
This figure shows a state where the coordinate value P (U, V, W) of the contact point P in the three-dimensional coordinate system when pressed against the surface Ws of p is measured by the displacement detection type measuring head 10. The tracing stylus 14 of the measuring head 10 is pushed back by the contact with the surface Ws even when the tracing stylus 14 is moved relative to the object to be measured Wp and mechanically moved to a position indicated by a dashed line together with the support shaft 12. The actual support shaft 12 and the tracing stylus 14 reach the position shown by the solid line, and the position of the center T of the tracing stylus 14 is
Is recognized. At this time, the detection axis (not shown) of the displacement detection type measuring head 10 incorporating the displacement detection means is
The tracing stylus 14 has reached a position (the position of the center Q) as if it was sunk into the position of the dashed line. The position coordinates (X, Y, Z) of the center Q in the three-dimensional coordinate system are nothing but the respective position data in the X, Y, Z axis directions of the detection axis of the measuring head 10. Therefore, the position coordinates Q () are output as output data of position detecting means such as an optical linear scale or a rotary encoder of a feed shaft motor provided in the feed shaft system in the relative movement between the workpiece Wp and the measurement head 10. X, Y, Z) can be obtained.

On the other hand, the tracing stylus 14 is connected to the surface Ws of the workpiece Wp.
As a result, the center of the spherical portion of the tracing stylus 14 is actually displaced in a substantially normal direction with respect to the same plane Ws in the three-dimensional coordinate system. The generated displacement amount E is detected as displacement components (I, J, K) in the X, Y, and Z axis directions by the displacement detecting means of the measuring head 10. Therefore, the coordinate values (U, V, W) at the contact point P of the surface Ws of the workpiece Wp are defined by the following arithmetic expressions (1) to (3) as is clear from the drawing.

U = X− (RE) · I / E (1) V = Y− (RE) · J / E (2) W = Z− (R−) E) · K / E (2) In other words, in the measuring method and the apparatus using the conventional displacement detection type measuring head, the condition that the radius of the spherical portion of the tracing stylus always coincides with the generated displacement ( Although setting a reference displacement amount E ₀₎ on measurements performed, in the present embodiment, R = the surface of the workpiece Wp measuring element 14 by an arbitrary generating displacement E without measured at a point which is E , And accurate coordinate values (U, V, W) of the surface coordinates P can be obtained from the displacement data E generated when the body is pushed inward and the position data of the detection axis of the measuring head 10. . In addition, the above arithmetic expressions (1) to
The calculation according to (3) can be performed by, for example, a control device of a drive system that performs relative movement between the workpiece Wp and the measurement head 10, for example, a calculation unit provided in an NC device. It can also be achieved by providing appropriate arithmetic means.

Referring now to FIG. 2, in this case, the contact point when the tracing stylus 14 of the displacement detection type measuring head 10 is pressed against the measured object Wp is applied to the surface Ws of the measured object Wp. This is a principle of a measuring method for measuring coordinate values (x, y, z) in a three-dimensional coordinate system of a point S offset by a distance r _{0 in a} substantially normal direction. Needless to say, the position of this point S is not necessarily the center position of the spherical portion of the tracing stylus 14.

For example, the center Q (X, Y, Z) of the tracing stylus 14 of the measuring head 10 is moved by the reference displacement E ₀
Although it is attempted to push the actuator into the position p, it is actually shown that the actuator is pushed to the position T where the combined displacement E (the displacement components in the X, Y, and Z directions are I, J, and K) is generated. I have. In this case, the offset distance (amount) r ₀ is (R−E ₀ ), as is clear from FIG. 2, and is a preset amount.

In this case, the coordinate value (x,
(y, z) is obtained from the following arithmetic expressions (4) to (6). x = X + (E−E ₀ ) · I / E (4) y = Y + (E−E ₀ ) · J / E (5) z = Z + (E−E ₀ ) · K / E (6) The arithmetic means for actually executing the arithmetic expressions (4) to (6) is a feed mechanism for the relative movement between the workpiece Wp and the measuring head 10 as described above. May be formed by an arithmetic means provided in a control device such as an NC device for controlling the control.

By executing the above-described calculation, the radius of the spherical portion of the tracing stylus 14 and the reference displacement E ₀ are made to coincide with each other, that is, in the system of FIG. 2, at the point where R = E _0. Even if measurement is not performed, the displacement data and the position data in a state where the tracing stylus 14 is pushed toward the surface Ws of the workpiece Wp by an arbitrary amount E are accurately offset by the offset distance r _{0 with} respect to the surface Ws. The coordinates of the position can be determined.

Next, an application of the measurement using the measuring head 10 and the tracing stylus 14 thus obtained will be described below. In the above-described process of measuring the workpiece Wp by contacting and pressing the measuring element 14 of the displacement detection measuring head 10, the coordinates (x, x) of the offset position S of the measuring element 14 are measured.
First, considering how the data obtained as (y, z) can be used, for example, as shown in FIG. 6 in FIG. 6 to FIG. if you get the coordinate value data of the position S, to measure the distance h from the position l ₃ points along the other side Ws for the straight line connecting the position l ₁ and l ₂ points along the surface Ws of the object Wp If the offset distance r ₀ is added, distance measurement data between both surfaces can be obtained.

Further, the point positions l ₁ , l ₂ , l ₃ along the arc corresponding to the spherical surface Ws of the DUT Wp are measured, and the offset distance r ₀ is added to determine the center position and radius of the arc. The required measurement can be performed (FIG. 7).
Further, the distance between the centers of a plurality of holes formed in the object to be measured Wp,
That is, the pitch distance is set in the X, Y, Z axis directions (X, Y in the drawing).
(Indicated on the axis and the simplified diagram) can be measured (FIG. 8). That is, as shown in FIG. 8, for different circular holes, a plurality of points, l ₁ , l ₂ , l ₃ and l ₄ , l ₅ , l
_{From 6} , the center position data of each circular hole is obtained, and from the obtained center position data, the calculation and measurement of the pitch distance can be performed.

On the other hand, FIG. 9 shows a case where the distance from the center position of a circular hole formed in the workpiece Wp to a straight line along another surface Ws is calculated and measured. Also in this case, the center position of the circular hole is determined from the measurement points l ₁ , l ₂ , l ₃ , while the linear position along another plane is determined from the points l ₄ , l ₅ , and the distance h is determined from both. It is. That is, FIGS. 6 to 9 show a case in which the dimension measurement of the object Wp is generally performed, and a predetermined distance from the surface of the object Wp can be obtained without obtaining the coordinate value of the surface Ws of the object Wp. point only was offset l ₁
By measuring the coordinate value data of ~ l _6, the measured object Wp
As a result, the measurement of the dimension data can be calculated and measured.

FIGS. 4 and 5 show an application example in which the coordinate value data of the contact point between the surface Ws of the workpiece Wp and the tracing stylus 14 of the measuring head is obtained according to the measuring principle shown in FIG.
FIG. 5 shows a case where a point along a spherical surface or an arc is measured, and FIG. 5 shows a case where an intersection point of two straight lines along two surfaces and an angle θ formed at the intersection point are obtained. As is clear from the above description, according to the present invention, the tracing stylus 14 of the displacement detection type measuring head 10 is relatively moved with respect to the measured object Wp, during which the contact between the tracing stylus 14 and the surface of the measured object is caused. In the case where the coordinate measurement of the contact point is performed from the state and the coordinate value of the position offset from the contact point is calculated and measured, as in the related art, the arbitrary displacement E can be obtained without being caught by the reference displacement E _0. The fact that the measurement principle shown in FIG. 2 is superior to the measurement principle shown in FIG. 1 will be described below.

That is, when a slight error θ occurs in the direction of the displacement vector of the tracing stylus 14 due to the friction between the tracing stylus 14 of the displacement detecting type measuring head 10 and the workpiece Wp,
According to the measurement principle of FIG. 1, the measured value of the surface coordinates is Rtanθ.
(R: tracing stylus radius) error occurs, and the error tends to increase as R increases and E decreases. On the other hand, FIG.
According to the measurement principle described above, the value of the difference value (E−E ₀ ) between the combined displacement and the reference displacement can be obtained without using the radius R of the tracing stylus 14 as is clear from the above-described arithmetic expressions (4) to (6). Is used. That is, in many cases, the tracing stylus 14 is pushed into the measured object Wp so that E becomes E ₀ , and after actual measurement, it stops at a position of E slightly different from E _{0 in} many cases.
₀ ) is a very small value. As described above, since FIG. 2 is not related to the radius R of the tip spherical portion of the tracing stylus 14,
This is excellent in that higher-precision measurement can be performed without being affected by the accuracy of the dimension value data of the tip spherical portion.

Therefore, in the actual measurement process of the measured object Wp, whether the item to be measured should be based on the measurement principle of FIG.
After determining whether to use the measurement principle shown in FIG. 2, it is necessary to perform measurement. That is, in the application examples shown in FIGS. 4 and 5, a method according to the measurement principle of FIG. 1 (operation steps for executing the arithmetic expressions (1) to (3) using the surface coordinate operation means) is effective.

On the other hand, in the application of FIG. 6 to FIG. 9, the measurement principle of FIG.
It can be said that a method according to (operation steps for executing (6)) is effective. Now, referring to FIG. 3, there is shown a measuring apparatus corresponding to the invention described in claim 5 of the present application.

In FIG. 3, the object to be measured Wp is mounted on, for example, a device known as a three-dimensional measuring device to perform measurement. The device comprises a fixed bed 20 and a bed 2
0, an upright column 22 movable in the Y-axis direction shown in the figure, a table 24 movable left and right in the X-axis direction orthogonal to the Y-axis with respect to the column 22, A spindle head 26 supported on the front surface of the co-column 22 so as to be slidable in a Z-axis direction orthogonal to the X and Y axes, and a spindle head 2;
6 and a displacement detection type measuring head 10 attached to the distal end portion, and the above-described measuring element 14 is detachably attached to the distal end of the measuring head 10.

The object to be measured Wp is mounted and held on the table 24, and the column 22, the table 24,
Due to the relative movement of the spindle head 26, the tracing stylus 1 of the measuring head 10
4 can be brought into contact with the surface of the workpiece Wp. At this time, the relative movement amounts of the column 22, the table 24, and the spindle head 26 are, for example,
X, Y, and Z axis scales 30 including optical scales and the like,
32 and 34, and these movements are performed by a well-known feed mechanism such as a ball screw mechanism (not shown) which operates in response to a command from the NC device 36 forming the control device. It has a configuration that is performed.

The above-described X, Y, and Z axis scales 30 to 34
, And the displacement detection data (I, J, K) of the displacement detection type measuring head 10 are sent to a position reading means 38, which further outputs a surface coordinate calculating means 40 and an offset coordinate calculating means 42. Has been sent to. In the illustrated example, for the sake of simplicity of explanation, these two arithmetic means 40 and 42 are shown separately, but these are
For example, it is also possible to use an arithmetic unit built in the NC device 36. Further, both calculation means 40 and 42
Is connected to a parameter storage unit 44 that stores in advance the parameters used in the above-described arithmetic expressions (1) to (6),
Required parameters can be read out in the calculation process.

On the other hand, the surface coordinate calculating means 40 and the offset coordinate calculating means 42 perform the measurement for enabling the use of the surface coordinate position measurement mode and the offset position measurement mode as necessary, as described above. Mode determination means 4
The measuring mode discriminating means 46 is connected so as to be able to discriminate a desired measuring mode in accordance with a command from the NC device 36.

The measuring mode determining means 46 is connected to a measuring value calculating means 48 for measuring a finally required measuring value in accordance with the measuring mode. It is configured to output to a well-known output unit 50 such as a display device or a printer. Next, a measurement process by the above-described measurement device will be described.

An NC program for instructing a measurement procedure is given to the NC device 36, and measurement is started. The relative movement between the workpiece Wp and the tracing stylus 14 of the measuring head 10 is performed,
When the position reading means 38 reads that the combined displacement amount has reached E ₀ at the first measurement point, a feed axis stop command (skip signal) is sent from the position reading means 38 to the NC device 36. X, Y, and Z coordinate values at the stopped position and each axis component (I, J, K) of the generated displacement amount E are represented by X,
The position reading means 38 takes in the detection data sent from the Y and Z axis scales 30 to 34 and the measuring head 10 and sends them to the surface coordinate calculating means 40 or the offset coordinate calculating means 42.

At this time, a known numerical value (measurement element sphere radius R
And the reference displacement amount E ₀ ) are stored in the parameter storage unit 44 in advance, and are read out from the parameter storage unit 44 as needed and used for calculation. Measurement mode determination means 46
Indicate that the measurements currently performed from the NC device 36 are shown in FIGS.
The information on the deviation of the measurement item is obtained, and it is determined whether the measurement item is the shape measurement mode or the dimension measurement mode.

At this time, in the case of the shape measurement mode, the calculation result from the surface coordinate calculation means 40 is used, and in the case of the dimension measurement mode, the calculation result from the offset coordinate calculation means 42 is used. The measurement value calculation suitable for the item is performed by the measurement value calculation means 48, and the calculation result is output to the output means 50 in the form of display data or record data.

As is clear from the above description, if the measuring apparatus of the embodiment shown in FIG. 3 is used, the required measurement for the object to be measured is the shape measurement, or the diameter and the depth of the circular hole. The required measurement can be performed with high accuracy and automatically by switching according to the measurement mode according to whether the measurement is a dimension measurement for obtaining a dimension such as a dimension, a gap or a width between two surfaces separated by a space. It is.

[0035]

As can be understood from the above description, according to the present invention, an object to be measured is measured by using a displacement detecting type measuring head.
In addition, a measurement device that directly performs the same method as the measurement method of performing the calculation and measurement according to a predetermined calculation formula is provided.At this time, the radius of the tracing stylus of the measurement head does not match the combined displacement amount, Since measurement is now possible, it is not necessary to precisely position the probe with respect to the measurement point of the workpiece during the measurement process, and it is possible to perform efficient measurement by increasing the relative feed speed. It was.

Further, even if the radius of the tracing stylus does not match the resultant displacement, the coordinates of the surface coordinates and the offset position can be obtained accurately and automatically by calculation. Moreover, since the calculation results can be obtained sequentially and the final measurement value can be calculated and measured while appropriately selecting the calculation means that matches the measurement conditions and measurement items of the DUT, the accuracy of the measurement results is improved. This can be reflected in the improvement of the processing accuracy of the workpiece.

[Brief description of the drawings]

FIG. 1 shows a state in which a stylus supported so as to be displaced in a substantially normal direction against the same surface of a displacement detection type measuring head is pressed against the surface of an object having a three-dimensional shape in a three-dimensional coordinate system. It is a principle diagram for measuring the coordinate value of a contact point.

FIG. 2 shows a point S (usually a spherical measuring element) that is offset by a distance r _{0 in the} normal direction from a contact point when the measuring element of the displacement detection measuring head is pressed against the surface of the object having the three-dimensional shape. FIG. 6 is a principle diagram for measuring coordinate values of (internal points).

FIG. 3 shows coordinate values of a contact point or an offset point of an object to be measured according to the principle shown in FIG. 1 or FIG. 2 while controlling relative movement between the object to be measured and the displacement detection type measurement head; FIG. 3 is a block diagram showing a configuration of a measuring apparatus that measures the coordinate values of S and classifies them into two measurement modes and automatically performs measurement in a desired mode.

FIG. 4 is a diagram schematically illustrating a relationship between a measuring point and a tracing stylus in a two-dimensional coordinate system when measuring a coordinate value of a certain point on the surface of the object to be measured.

FIG. 5 is a schematic diagram for explaining a measurement method for obtaining an intersection between two straight lines on the surface of the object to be measured and an angle formed by the two straight lines at the same intersection.

FIG. 6 is a schematic diagram illustrating a method of measuring a distance between two surfaces of an object to be measured by replacing the distance with a distance between two straight lines in a two-dimensional coordinate system.

FIG. 7 is a schematic explanatory diagram illustrating a circular arc measurement applicable to a radius measurement of a spherical surface of a measurement object in a two-dimensional coordinate system.

FIG. 8 is a schematic diagram for simply describing a measurement method in a two-dimensional coordinate system when applied to measurement of a pitch dimension of a large number of holes formed in an object to be measured.

FIG. 9 is a schematic diagram for explaining a measurement method when applied to the distance measurement between the center of a circular hole formed in a measured object and another surface of the measured object in a two-dimensional coordinate system. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Displacement detection type measuring head 12 ... Support shaft 14 ... Measuring element 20 ... Fixed base 24 ... Table 26 ... Spindle head 36 ... NC device 38 ... Position reading means 40 ... Surface coordinate calculating means 42 ... Offset coordinate calculating means 46 ... Measurement Mode discriminating means 48: Measured value calculating means

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuzo Takeuchi 359 3-3, Masu, Aikawa-cho, Aiko-gun, Kanagawa Prefecture Inside Makino Milling Machinery Co., Ltd. Hei 2-220106 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 21/00-21/32 B23Q 17/20 G05B 19/408

Claims (2)

(57) [Claims] 1. A relative movement in the X, Y, and Z-axis directions is performed between an object having a three-dimensional shape and a measurement head, and a contact point of the measurement element of the measurement head is brought into contact with the object to be measured.
And a measuring method for measuring a coordinate value of a position offset from a surface of the workpiece , wherein the measuring head has a spherical portion at a tip and is substantially normal to the surface when the surface comes into contact with the surface of the workpiece. A probe supported to be displaced in the direction, and the X, Y, and
Using a displacement detection type measuring head capable of detecting each displacement in the Z-axis direction, an item to be measured determines a coordinate of the surface of the object to be measured.
In the first measurement mode that requires a step,
Step for finding the coordinates of a point offset by a predetermined amount from the surface
Determines second measurement mode that requires flop, said for the first measurement mode and the measurement item is determined, before
The position data of the displacement detection type measuring head in the X, Y,
And the coordinate value (U, V, W) of the contact point when the measuring element of the displacement detection type measuring head is brought into contact with the surface of the object to be measured.
The, U = X- (R-E ) · I / E ········· (1) V = Y- (R-E) · J / E ········· ( 2) W = Z− (RE) · K / E (3) In this case, R is a known value of the radius of the tip sphere of the tracing stylus, I, J, K Are X, Y,
Each displacement in the Z-axis direction, E is the combined displacement of the tracing stylus and E = √ (I ² + J ² +
K ² ), that is, the value of E is equal to the square root of (I ² + J ² + K ² ). X, Y, and Z are the respective position data of the displacement detection type measuring head when the displacement is detected upon contact. determined according represented by (1) to (3), wherein for the second measurement mode and the measurement item is determined, X of the displacement detection type measuring head, Y, each position in the Z axis direction
Read the data and measure the displacement detection type measuring head on the surface of the object to be measured.
Offset by a predetermined amount from the point of contact when the
Coordinate value of the position (x, y, z) and, x = X + (E- E 0) · I / E ······· (4) y = Y + (E-E 0) · J / E (5) z = Z + (E−E ₀ ) · K / E (6) In this case, E ₀ is a preset reference displacement and is measured.
The predetermined offset amount r ₀ is subtracted from the radius R of the tip ball portion of the child.
The amounts I, J, and K are X, Y, and
Each displacement in the Z-axis direction , E is a combined displacement of the tracing stylus, and E = √ (I ² + J ² +
K ² ), the value of E is the square root of (I ² + J ² + K ² )
Equal to, X, Y, Z is the displacement detection when detecting a contact with the displacement
Measurement method, characterized in that each position data in the form measuring F head, determined in accordance with (4) - (6), so as to. 2. A relative movement in the X, Y, and Z-axis directions is performed between an object having a three-dimensional shape and a measuring head, and a measuring element of the measuring head is brought into contact with the object to measure a coordinate value or a coordinate value. In a measuring apparatus for measuring dimensions, the measuring head includes a measuring element having a spherical portion at a tip and supported to be displaced in a substantially normal direction with respect to the surface of the object to be measured when the surface comes into contact with the surface. , X, Y, Z of the probe
Position reading means formed as a displacement detection type measuring head capable of detecting each displacement in the axial direction, reading position data in the X, Y, and Z directions of the displacement detection type measuring head; Coordinate values (U, V, W) of the contact point when the probe of the displacement detection type measuring head is brought into contact
U = X− (RE) · I / E (1) V = Y− (RE) · J / E (1) 2) W = Z− (RE) · K / E (3) where R is a known value of the radius of the tip sphere of the tracing stylus, and I, J, and K are displacements X, Y, detected by the detection type measuring head
Each displacement in the Z-axis direction, E is the combined displacement of the tracing stylus and E = √ (I ² + J ² +
K ² ), that is, the value of E is equal to the square root of (I ² + J ² + K ² ). X, Y, and Z are the respective position data of the displacement detection type measuring head when contact is detected. (1) to (3) surface coordinate calculating means; and a coordinate value of a position offset by a predetermined amount from the contact point when the tracing stylus of the displacement detection type measuring head is brought into contact with the surface of the workpiece. (X, y, z) is calculated as follows: x = X + (E−E ₀ ) · I / E (4) y = Y + (E−E ₀ ) · J / E .. (5) z = Z + (E−E ₀ ) · K / E (6) where E ₀ is a preset reference displacement amount and the radius of the tip spherical portion of the tracing stylus. An amount obtained by subtracting a predetermined offset amount r ₀ from R, I, J, and K are X, Y, and X detected by the displacement detection type measuring head.
Each displacement in the Z-axis direction, E is a combined displacement of the tracing stylus, and E = √ (I ² + J ² +
K ² ), that is, the value of E is equal to the square root of (I ² + J ² + K ² ). X, Y, and Z are the respective position data of the displacement detection type measuring head when the displacement is detected upon contact. 4) to (6), an offset coordinate calculating means, and X, Y, and X values of the object to be measured and the displacement detection type measuring head.
An NC device for controlling the relative movement in the Z-axis direction, and an item to be measured in a first measurement mode which requires a step of obtaining surface coordinates of the object to be measured, or a point offset by a predetermined amount from the surface of the object to be measured. Measurement mode discrimination means for discriminating a second measurement mode which requires a step of obtaining coordinates of the first and second measurement modes; and for a measurement item determined by the discrimination means to be the first measurement mode, a measurement value is obtained using an output of the surface coordinate calculation means. look, the determining means measuring device for measurement items is determined that the second measurement mode is characterized by comprising a measurement value calculating means for obtaining a measured value by using an output of the offset coordinates calculation means.