JP3608374B2 - Hole measurement method with 3D measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a hole formed in a workpiece, and more particularly to a method for measuring the coordinates of a hole with a three-dimensional measuring instrument.
[0002]
[Prior art]
For example, a manufacturing process for an automobile or the like includes a hole forming process for forming a circular hole in the workpiece w. The hole formed in such a process is measured by a so-called three-dimensional measuring instrument, and it is determined whether or not the hole is formed as designed.
[0003]
FIG. 8A is a top view of a circular hole 1 having a radius r formed on the workpiece w. When the hole 1 is measured by a three-dimensional measuring instrument, a probe (probe) is moved inside the hole 1 by a controller (not shown) and sequentially brought into contact with the inner wall s of the hole 1, and the point where the probe comes into contact with the inner wall s is determined. Record as coordinates. From the coordinates of the recorded points, the coordinates of the center c of the hole are calculated. The measurer can determine whether or not the hole 1 is formed at the designed position from the coordinates of the center c of the hole.
[0004]
At this time, even when the hole 1 is formed at the position as designed on the workpiece w, if the surface of the workpiece w is inclined, the coordinates of the hole 1 to be measured are shifted. Therefore, in general, in such measurement of the hole 1, prior to the measurement of the hole 1, for example, a circle 3 having a radius larger than the radius r of the hole 1 by a length d is set. The height is measured at a plurality of points m located at. Then, the inclination of the workpiece w is obtained by calculating a surface including the three measured points, and the coordinates of the center c of the measured hole 1 are projected on the surface of the workpiece w, and generated by the inclination of the workpiece w. The error of the center c coordinate is corrected.
[0005]
The series of operations such as the measurement of the point m and the calculation of the coordinates of the center c are performed by a preset program.
[0006]
[Problems to be solved by the invention]
The surface of the workpiece w on which the hole 1 is formed is not always horizontal. That is, for example, there is a case where the convex portion 100 is provided on the work w in FIG. 8A and has a cross-sectional shape as shown in FIG. At this time, if the point m on the circle 3 is set on the convex portion 100, the inclination of the workpiece w cannot be obtained accurately.
[0007]
Therefore, the measurer determines the distance from the center point of the hole 1 to the point m, that is, the radius of the circle 3 so that the point m is not set on the convex portion 100 while monitoring the state of the workpiece w and the hole 1. Then, the program automatically divides the circumference of the circle 3 set by the measurer by a predetermined center angle θ and automatically determines a point to be measured for obtaining the inclination of the workpiece w.
[0008]
However, for example, when the measurer cannot recognize the convex portion 100 on the monitor, the point m is set on the convex portion 100 by mistakenly setting the circle 3, and an accurate inclination of the workpiece is obtained. There is no possibility. In such a case, an error occurs in the coordinates of the center c of the hole 1, and the reliability of the measurement of the hole 1 by the three-dimensional measuring instrument is lowered.
[0009]
The present invention has been made in view of the above points, and eliminates the influence of workpiece undulation on the calculation of the inclination of the workpiece w, and provides a more reliable hole measurement method using a three-dimensional measuring instrument. The purpose is to do.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 for solving the above problems is a hole measuring method by a three-dimensional measuring instrument that measures the coordinates of holes formed in a workpiece with a probe according to a set program, Prior to the measurement of the hole, a first step of setting a measurement region for measuring the inclination of the work surface on which the hole is formed, a second step of measuring the coordinates of a plurality of measurement points in the measurement region,
The shape of the measured surface to be formed from the measurement point coordinates, by comparing the shape of the predetermined face, and a third step of detecting an inflection point on the workpiece surface, the inflection point A fourth step of setting a re-measurement area by removing an existing area from the measurement area; and a workpiece in which the hole is formed with the inclination of the surface determined based on the coordinates of a plurality of measurement points in the re-measurement area And a fifth step for setting the inclination of the surface.
[0011]
By comprising in this way, the presence or absence and position of the workpiece | work undulation can be investigated. If the workpiece has undulations in the set measurement area, it is possible to automatically set an area without undulations in the workpiece as the measurement area to obtain the inclination of the workpiece. Therefore, more accurate measurement data can be acquired except for measurement errors caused by human error such as the measurement person setting an inappropriate measurement region.
[0012]
According to a second aspect of the present invention, the second stage and the third stage are repeatedly performed until the inflection point is not detected.
[0013]
By comprising in this way, the inclination of a workpiece | work surface can be determined with the measurement area | region where the area | region where an inflection point exists was removed reliably. Therefore, the reliability of hole measurement performed based on the inclination of the workpiece surface can be further increased.
[0014]
According to a third aspect of the present invention, the measurement region is set on a circumference of a circle having a center point of the hole set on the program as a center point and a radius larger than the radius of the hole. It is characterized by that.
[0015]
By configuring in this way, it is possible to easily set a measurement region around a hole that seems to affect the measurement of the hole with respect to a substantially circular hole. Therefore, the setting of the measurement area can be simplified and the hole measurement can be performed efficiently.
[0016]
The invention described in claim 4 is characterized in that the determined inclination of the workpiece is used in an inspection process for inspecting the formation position of the hole.
[0017]
By configuring in this way, it is possible to eliminate the measurement error of the hole formation position due to the tilt of the workpiece, and to improve the reliability of the inspection process.
[0018]
【The invention's effect】
According to the first aspect of the present invention, more accurate measurement data can be acquired except for measurement errors caused by human error such as a measurement person setting an inappropriate measurement region. In addition, the presence or absence of an inflection point can be easily confirmed by comparison with a preset surface shape.
[0019]
The invention according to claim 2 can further improve the reliability of the hole measurement performed based on the inclination of the workpiece surface.
[0020]
Further, the invention according to claim 3 can simplify the setting of the measurement region so that the hole measurement can be performed efficiently.
[0021]
The invention according to claim 4 can eliminate the measurement error of the hole formation position due to the tilt of the workpiece, and can improve the reliability of the inspection process.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram illustrating a schematic configuration of a general three-dimensional measuring device.
The probe 10 is used to input the coordinates of each part in contact with the surface of the workpiece w. The probe 10 is moved by a probe driving unit 15. The coordinates of the contact position of the probe 10 are measured by the coordinate measuring unit 20. The measurement operation control unit 30 controls the operation of the probe drive unit 15 and stores the coordinates measured by the coordinate measurement unit 20.
[0023]
The probe driving unit 15 operates according to a program stored in the operation control unit 30. The program for measuring the hole includes a process for determining a measurement point for obtaining the inclination of the surface of the workpiece w, a process for calculating the surface of the workpiece w based on the measured coordinates, and a calculation A series of operations for hole measurement based on the surface of the workpiece w is stored.
[0024]
FIG. 2 is a diagram for briefly explaining a method of measuring the hole 1 by the three-dimensional measuring device of the present embodiment.
In the present embodiment, a hole measuring method using a three-dimensional measuring instrument is used for measuring the inclination of the surface of a work performed prior to hole measurement.
[0025]
The illustrated hole 1 is a perfect circular hole having a radius of r, and is arranged on the workpiece w side by side in the DIR2 direction in the figure. On the other hand, the probe 10 (FIG. 1) of the three-dimensional measuring instrument that measures the hole 1 is located above the hole 1. Each time the measurement of one hole 1 is completed, the workpiece w moves in the DIR2 direction at the pitch of the holes 1 and sequentially feeds the holes 1 to be measured to the lower side of the probe 10.
[0026]
In the program, the probe 10 is lowered from above the hole 1 onto the workpiece w, and a circle 3 having a radius of r + d around the design center point o of the hole 1 is set. Then, a plurality of points on the circumference of the circle 3 are measured and recorded as coordinates. The point on the circumference of the circle 3 is a three-dimensional coordinate using a point on the axis DIR1 of the radius R of the circle 3, the angle θ formed by the radius R and the axis of DIR2, and the normal direction of the inner surface of the hole 1 ( 3).
[0027]
FIG. 4 is a diagram for explaining a procedure for determining measurement points for measurement performed to obtain the inclination of the surface of the workpiece w. In the present embodiment, first, the probe 10 is lowered to the design center point o of the hole 1, and the probe 10 is placed at one point on the circumference of the circle 3 on the workpiece w (point e in the figure) according to the program. Moving. Then, the central angle of the circle 3 is divided into four equal parts clockwise from the point e, and the points f, g, and h are determined as measurement points as shown in FIG.
[0028]
When the measurement points of point e, point f, point g, and point h shown in FIG. 4A are described in the R, θ, and DIR1 coordinates, all the measurement points are the same as shown in FIG. 4B. This surface is a square. Therefore, the inclination of this surface can be made the inclination of the surface of the workpiece w.
[0029]
Then, the center point c of the hole 1 determined by the measurement of the hole 1 is projected onto a surface having this inclination on the program, and the measurement error of the center point measurement due to the inclination of the surface of the workpiece w is corrected.
[0030]
5 and 6 are diagrams illustrating an example in which the work w illustrated in FIG. 4 is measured by another program.
In the example of FIG. 5 as well, the probe 10 is lowered to the center point o as in the example described in FIG. 4, and the probe 10 is moved to one point on the circumference of the circle 3 on the workpiece w (point a in the figure) according to the program. To move. Then, the central angle of the circle 3 is divided into four equal parts clockwise from the point a, and the measurement point b, measurement point c, and measurement point d are determined as shown in FIG. In the example of FIG. 5A, the measurement point c is set on the convex part 100 as a result of the above measurement point determination.
[0031]
FIG. 5B is a diagram in which the coordinates of measurement point a, measurement point b, measurement point c, and measurement point d in FIG. 5A are shown in R, θ, and DIR1 coordinates. If the surface of the workpiece w is a plane having a certain inclination, the measurement points of the points a, b, c, and d are on the same plane. In particular, in the present embodiment, a square surface should be formed by the measurement points of point a, point b, point c, and point d.
[0032]
However, according to FIG. 5B, the surface formed by the measurement points of point a, point b, point c, and point d is not a square. However, when the DIR coordinates of the measurement point c are corrected to be small, a square surface w ′ including three points of the measurement point a, the measurement point b, and the measurement point d can be set. Therefore, it can be seen that only the measurement point c is higher than the surface w ′. This is a result of the measurement point c being set on the convex portion 100 as shown in FIG. In the present embodiment, a measurement point that is determined not to be in the same plane including other measurement points, such as measurement point c, is referred to as an inflection point.
[0033]
In other words, even if the workpiece plane is a plane with no undulations, it is difficult to determine whether the acquired data represents the undulations or the inclination of the workpiece depending on the degree of inclination and the number of measurement points if the workpiece plane is inclined overall. Can be considered. In such a case, when all the measurement points are included in the same surface as in the present embodiment, the shape of the surface formed by the measurement points is set on the program in advance, and the inflection point is increased. By correcting the position in the vertical direction, it can be easily detected as a point where a surface on which measurement points are set can be formed.
[0034]
The measurement operation control unit 30 determines from the above measurement results that there is a portion where the surface shape of the workpiece w is convex in the range from the measurement point b to the measurement point. Then, the measurement operation control unit 30 divides the circumference from the measurement point b to the measurement point d, which is an area excluding the measurement point b and the measurement point d from the circumference of the circle 3, into four equal parts as shown in FIG. Measurement point i, measurement point j, measurement point k, and measurement point l are determined. When the measurement coordinates of each point are entered in the R, θ, and DIR1 coordinates to set the surface, and the coordinates of measurement point i, measurement point j, measurement point k, and measurement point l are on the set surface In this case, the inclination of this surface is regarded as the inclination of the surface of the workpiece w and is used to determine the center point c of the hole 1.
[0035]
FIG. 7 is a flowchart for explaining the processing of the present embodiment described above.
[0036]
In the processing of the present embodiment, first, the workpiece w is transported so that the probe 10 is placed on the hole 1 to be measured, and the hole 1 to be measured is recognized through a monitor or the like (S1). When the measurement target hole is recognized (S2), a workpiece undulation survey is performed to investigate whether there is a undulation on the workpiece w by the method described with reference to FIGS. 4 to 6 (S3).
[0037]
As a result, when there is no inflection point in the measurement point (S4: NO), all measurement regions (circumference of circle 3 in the present embodiment) are equal to the number of measurement points set in the program. The measurement points for performing surface measurement for measuring the inclination of the surface of the workpiece w are determined (S7).
[0038]
On the other hand, when there is an inflection point in the measurement point (S4: YES), the position of the inflection point is recognized from the coordinates (S5), and it can be determined that the inclination of the work w in the measurement region is constant. Only the “slope constant part” is equally divided by the number of measurement points set in the program, the measurement point for measuring the surface of the workpiece w is determined (S6), and the inclination of the workpiece w is determined. The requested process is terminated.
[0039]
If an inflection point is detected in the process of step 4 in the flowchart described above, it is determined whether there is an inflection point after the process of step 5 and this process is repeated until no inflection point is detected. Anyway.
[0040]
In the present embodiment described above, the presence / absence and position of the workpiece w can be checked. If the workpiece w is undulated in the set measurement area, the area without the undulation in the workpiece can be automatically newly set as a remeasurement area to obtain the tilt of the workpiece.
[0041]
Therefore, more accurate measurement data can be acquired except for measurement errors caused by human error such as the measurement person setting an inappropriate measurement region.
[0042]
In the present embodiment, a circle 3 having a radius larger than that of the hole 1 centered on the design center point of the hole 1 is set for the circular hole 1, and this circumference is set as a measurement region. ing. For this reason, the measurement area | region for measuring the inclination of the workpiece | work w in the position of the workpiece | work w which seems to influence the measurement of the hole 1 can be set automatically. Therefore, the process for obtaining the inclination of the workpiece w can be simplified.
[0043]
Further, the present embodiment eliminates the measurement error of the formation position of the hole 1 due to the inclination of the work w by using the determined inclination of the work in the inspection process of inspecting the formation position of the hole, and the reliability of the inspection process. Can be increased.
[0044]
In the present embodiment described above, four measurement points are used for calculating the inclination of the surface of the workpiece. However, the present invention is not limited to such an example. It is also good.
[0045]
Moreover, although embodiment described above has described the example which measures a hole of a perfect circle shape, this invention is not limited to such an example, For any shape hole. Can be applied. In such a case, for example, the circumference of a circle including the hole to be measured may be set as the measurement region.
[0046]
The present invention can also be applied to measurement of nuts, bolts and the like.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a general three-dimensional measuring device.
FIG. 2 is a diagram for briefly explaining a hole measuring method by a three-dimensional measuring device according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating coordinates for recording coordinates of measurement points according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining a procedure for determining measurement points for measurement performed to determine the tilt of a workpiece according to an embodiment of the present invention, wherein (A) is a diagram showing the positions of the measurement points; (B) is the figure which represented the measurement point described in (A) on the coordinate axis.
FIG. 5 is another diagram for explaining the procedure for determining the measurement point of measurement performed to determine the tilt of the workpiece according to the embodiment of the present invention, where (A) is a diagram showing the position of the measurement point; (B) is a diagram showing the measurement points described in (A) on the coordinate axes.
FIG. 6 is another diagram illustrating a procedure for determining measurement points for measurement performed to determine the workpiece inclination according to the embodiment of the present invention.
FIG. 7 is a flowchart illustrating processing performed in an embodiment of the present invention.
FIG. 8 is a diagram illustrating a problem of a conventional method for measuring the tilt of a workpiece.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hole 3 ... Circle 10 ... Probe 15 ... Probe drive part 20 ... Coordinate measuring part 30 ... Measurement operation control part 100 ... Convex part w ... Work o ... Center point on design of hole

Claims (4)

According to a set program, a hole measuring method by a three-dimensional measuring instrument that measures the coordinates of a hole formed in a workpiece with a probe,
Prior to the measurement of the hole, a first step of setting a measurement area for measuring the inclination of the work surface on which the hole is formed;
A second stage of measuring the coordinates of a plurality of measurement points within the measurement area;
A third step of detecting an inflection point on the work surface by comparing the shape of the surface formed from the coordinates of the measured measurement points with the shape of the preset surface;
A fourth step of setting a re-measurement area by excluding an area where the inflection point exists from the measurement area;
According to a three-dimensional measuring instrument, comprising: a fifth stage in which the inclination of the surface determined based on the coordinates of a plurality of measurement points in the remeasurement area is set as the inclination of the work surface on which the hole is formed. Hole measurement method. 2. The hole measuring method using a three-dimensional measuring instrument according to claim 1, wherein the second stage and the third stage are repeatedly performed until the inflection point is not detected. The measurement area is set on the circumference of a circle having a center point of the hole set on the program as a center point and a radius larger than the radius of the hole. Hole measurement method using the described three-dimensional measuring instrument. 2. The hole measuring method using a three-dimensional measuring instrument according to claim 1, wherein the determined inclination of the work surface is used in an inspection process for inspecting the formation position of the hole.

Images