JPH0213243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-dimensional measuring machine that measures the shape, size, etc. of an object to be measured using a three-dimensionally movable probe, and particularly to an apparatus used for the measurement.

In general, a three-dimensional measuring machine sequentially contacts a measuring point of a workpiece with a measuring element that is movable in three dimensions, that is, three orthogonal axes, X, Y, and Z axes.
The shape, dimensions, etc. of the probe are measured from the amount of displacement of the probe.

In such a three-dimensional measuring machine, in order to detect displacement in each of the X, Y, and Z axes, a photoelectric type, electromagnetic type, etc. length measuring detector is installed in each axis direction, and the output signal of this detector is The values at the moment when the probe touches the measurement point are sequentially stored in the attached computer, etc., and from this stored data, the shape of the object to be measured,
It is configured so that dimensions and the like are processed. At this time, in order to accurately capture the value at the moment of contact, the probe is formed to generate an electrical signal the moment it makes contact with the measurement point, and normally such a probe is used as a touch signal sensor. It is called.

By the way, in a coordinate measuring machine, in order to efficiently measure a complex-shaped object to be measured, in addition to an absolute coordinate system, a coordinate system suitable for an arbitrary measurement surface, that is, a so-called arbitrary coordinate system, can be selected. In this case, a function is provided that allows mutual coordinate transformation between the two coordinate systems, thereby making it possible to measure, for example, dimensions between the centers of holes determined using different coordinate systems. In addition, a common fixed point, that is, a so-called origin where the three coordinate axes intersect at right angles, is provided for each coordinate system so that coordinate conversion can be easily performed even if the measuring head is tilted with respect to the measuring machine body as appropriate for each arbitrary coordinate system. There is.

Therefore, in order to fully demonstrate the above-mentioned functions, in conventional three-dimensional measuring machines, the tip of the probe is spherical, and a reference block having a corresponding conical recess is used. There is. That is, a reference block is fixed on the measurement table, and by abutting the spherical tip of the probe against the concave portion of the reference block, the center of the sphere is virtually set as the reference origin. Therefore, the measurement coordinate value when the contact point touches the measurement surface needs to be corrected by adding the length equivalent to the radius of the sphere, rather than the amount of displacement of the contact point itself from the origin. .

In this way, in the conventional measurement method, it is necessary to correct the radius of the sphere of the spherical gauge head, so the measured value depends on where on the surface of the sphere the gauge head touches the measurement surface. This will result in an error. In other words, if the surface of a sphere that is on the axis of the stay that supports the spherical tip of the probe or the axis that is perpendicular to this axis makes contact with the measurement surface, the value to be corrected will be the same as that of the sphere. It must be the radius of the sphere multiplied by the sine or cosine of the angle, rather than the radius itself;
Since the angle of contact cannot be measured at once, it has been virtually impossible to perform measurements in which the sphere contacts the measurement surface at any arbitrary point.

Therefore, conventionally, the measuring point must be brought into contact with the measuring surface so that the axis of the measuring point or the axis perpendicular to this axis is perpendicular to the measuring surface.
In the second contact, only the value on one coordinate axis of the measurement surface is determined. For this reason, it has not been possible to measure a free-form surface that is not necessarily composed only of measurement surfaces in the same direction or perpendicular to the axis of the probe using conventional methods.

On the other hand, if the tip of the probe is sharp and the contact part with the measurement surface is a point, regardless of the contact direction, one contact will produce the values on the three coordinate axes of the measurement point. will be required at the same time. However, conventionally, a method and an apparatus for measuring a free-form surface while maintaining the coordinate conversion function of a three-dimensional measuring machine have not been developed. This is due to the fact that the origin of the three coordinate axes could not be detected reliably and quickly.

By the way, even in the conventional method, a so-called punching measuring element or a scribing measuring element with a sharp tip is well known, but these are used only in one coordinate axis direction. It was hot.

Due to the above-mentioned circumstances, there is a strong desire to establish simultaneous measurement of three coordinate values, which is the original purpose of a three-dimensional measuring machine.

An object of the present invention is to be able to simultaneously detect three-dimensional coordinates without impairing the mutual conversion function between an absolute coordinate system and an arbitrary coordinate system, and therefore to be able to accurately and efficiently measure free-form surfaces of objects to be measured. An object of the present invention is to provide a device for a measuring method of a three-dimensional measuring machine.

The present invention was made by focusing on the fact that the center of curvature of a spherical surface that can simultaneously contact three concave orthogonal planes that are perpendicular to each other and intersect at one point is always constant with respect to the intersection.

That is, the measuring method device of the present invention has a reference block having three concave orthogonal planes that are orthogonal to each other and intersect at one point, and a point-shaped minimal contact portion at the tip, and the axis including this contact portion can be moved in any direction. a hemisphere which is removably attached to the tip of the probe and has a spherical surface that can simultaneously contact three orthogonal planes of the reference block, and a point-shaped tip of the probe. An adapter for detecting the origin and a guide member for guiding the probe to be installed at the center of the sphere.

In the present invention, by simultaneously bringing the origin detection adapter attached to the tip of the probe into contact with three orthogonal planes of the reference block,
The coordinates of the tip of the probe with respect to the intersection of the reference blocks, that is, the origin of the orthogonal three axes, are detected, and by setting these coordinates as the origin of the probe, the origin of the orthogonal triaxial coordinates of the point measured by the probe is aligned with the direction of the probe. can be easily and accurately detected regardless of the

In addition, during measurement, by removing the adapter and bringing the tip of the probe, which is a point-shaped minimal contact part, into contact with the object to be measured, the orthogonal three-axis coordinates of the measurement point can be detected accurately and simultaneously, thereby achieving the above purpose. achieved.

Embodiments of the present invention will be described below based on the drawings.

A probe 2 is rotatably supported on a main body 1 of a three-dimensionally movable three-dimensional measuring machine, and a probe 3 is detachably attached to the probe 2. The tip of the probe 3 has a conical shape, and a point-shaped minimal contact portion 4 is formed at the tip, and this point-shaped tip comes into contact with a measurement point on the object 5 to be measured.

On the other hand, the measuring tip 3 whose tip is formed into a point shape
In order to determine the measurement reference point, that is, the coordinate origin, of the probe 2 to which the probe 2 is attached, as shown in FIG. It is conceivable to use a reference block 8 which rotatably holds a spherical block main body 7 so that the recess 6 of the measuring element 3 coincides with the axial direction of the probe 3.
At this time, the recess 6 of the spherical block main body 7 is machined with very high precision so that the origin does not change no matter which direction the probe 3 is oriented.
When inserted into the recess 6 of the spherical block body 7,
The tip of the probe 3 must be located at the center of the spherical block body 7 without fail.

However, in reality, the tip of the probe 3 is finished in a needle shape, and the tip of the probe 3 is finished in a needle shape.
It is extremely difficult to machine the recess 6 so that the tip thereof is located at the center of the spherical block body 7. Therefore, in actual use, an origin detection adapter 9 such as the embodiment shown in FIG. 3 is used.

The origin detection adapter is constructed by fixing an inner tube 11 as a guide member upright on a plane portion of a hemisphere 10 which is divided into two by a plane including the center of the sphere. When detecting the origin, the origin detection adapter 9 is inserted into the aforementioned probe 3, and the concave shape in which three planes facing inward are orthogonal to each other and intersect at one point as shown in FIGS. 4 and 6 is inserted. A reference block 12 is used.

Next, a measurement method using a three-dimensional measuring machine using this embodiment will be described.

Adjust the axis of the probe 3 in an appropriate direction according to the free-form surface of the object to be measured 5, for example, with respect to the X, Y, and Z axes.
Adjust the direction of probe 2 so that it is oriented around 55 degrees. Next, attach the origin detection adapter 9 to the probe 3.
The spherical surface of the hemisphere 10 of the origin detection adapter 9 is brought into contact with the three planes of the reference block 12, respectively. At this time, in advance, the hemisphere 1
By inputting data obtained by accurately measuring the radius of 0 into a computer or the like attached to the three-dimensional measuring machine, the position of the point-shaped minimal contact portion 4 of the measuring stylus 3 is detected as the origin.

Next, remove the origin detection adapter 9 from the gauge head 3, bring the point-like minimal contact portion 4 of the gauge head 3 into contact with the measuring point of the object to be measured 5, and
Detects Y and Z axis coordinates simultaneously.

When measuring a free-form surface or a flat surface in the same direction, there is no need to change the orientation of the probe 2 after the origin detection described above is performed once, but if you want to measure the opposite surface as shown in Figure 5, Unless the direction of the probe 3 is changed, the tip will not come into contact with the object to be measured 5, so measurement cannot be performed. Therefore, in this embodiment, the orientation of the reference block 12 is set on the measuring table (not shown).
Use a jig that is designed to be able to be turned in any direction. This is a measurement table that includes points that are inside the hemisphere 10 of the origin detection adapter 9 by the radius R from the other two of the three planes of the reference block 12, excluding the plane parallel to the measurement table. It is designed to rotate around an imaginary center line 13 that is perpendicular to the top, and by doing so, the reference block 1
Measurements can be made without changing the tip point position of the probe 3 no matter where the probe 2 is directed (see Fig. 7).

According to this embodiment as described above, the tip of the probe 3 is shaped like a needle so that the contact surface of the object to be measured is point-shaped, and the orientation of the probe 3 can be set to any direction, and the origin Detection adapter 9
Since the origin can be simultaneously detected in three axes using the reference block 12, the orthogonal three-axis coordinates of the measuring point of the object 5 can be detected simultaneously.

In this way, three-axis coordinates can be detected simultaneously with a single contact, which speeds up measurement work and improves accuracy.
Furthermore, while continuously detecting each contact point, the contact point 3
By moving the device, it can also be used as a contour measuring device, which was previously done using an analog method.

The origin detection adapter 9 has a cylinder 1 on a hemisphere 10.
1 is shaped to be fixed upright, manufacturing is simple and the tip position of the probe 3 can be determined accurately.

Furthermore, if the reference block 12 is modified as described above, it is possible to maintain the origin at a constant position regardless of the orientation of the probe 3, and there is no need to provide a calculation function or conversion base, etc., making it possible to prepare for measurement. The hassle is also reduced.

In the above embodiment, the tip of the probe 3 is conical, but it may also be in the shape of a polygonal pyramid such as a triangular pyramid, and the cylinder 11 is used as the guide member of the origin detection adapter 9. If it is guided so that the center of the measuring element 3 coincides with the center of the hemisphere 10, it can be a cylindrical one or the measuring element 3.
It may be a plurality of rod-shaped objects arranged so as to be in contact with the circumferential surface of the object. Furthermore, if it is desired to rotate the reference block 12 around the intersection of the three planes of the reference block 12, the reference block 12 can be oriented in any direction by calculating the radius R of the hemisphere 10. In addition, as shown in FIG. 8, a reference block 1 having two orthogonal three planes that are point symmetrical about the intersection point of three orthogonal axes, that is, the zero point.
4, it is possible to measure from directions 180 degrees apart, for example from the directions of arrows A and B on a straight line from the 1st and 3rd quadrants to the zero point, as shown in Figure 9. Become. Further, in the embodiment described above, the probe 2 is provided so as to be bendable, but in practice, other structures may be used, such as making the probe 2 and the probe 3 bendable.

As described above, according to the present invention, there is an effect that it is possible to provide an apparatus for a measurement method of a three-dimensional measuring machine that can simultaneously detect a measurement point on a free-form surface in three-axis coordinates.

[Brief explanation of drawings]

FIG. 1 is a partial front view of the vicinity of the measuring head of a coordinate measuring machine showing an embodiment of the measuring method apparatus according to the present invention;
FIG. 2 is a partially sectional front view for explaining the principle of the origin detection method of the measuring method apparatus according to the present invention, and FIG. 3 is a partially sectional front view showing an embodiment of the measuring method apparatus according to the present invention. FIG. 4 is a perspective view showing the origin detection state in FIG. 3, FIG. 5 is a front view showing a case where the object to be measured and the measurement point are different from those in FIG. 1, and FIG. 6 is an apparatus for the measuring method of the present invention. FIG. 7 is an explanatory diagram of the operation of FIG. 6, and FIG. 8 is another implementation of the device for the measuring method of the present invention. Perspective view of main parts showing an example, No. 9
The figure is an explanatory diagram of the operation of FIG. 2... Probe, 3... Measuring head, 4... Point-shaped minimal contact portion, 5... Measured object, 9... Origin detection adapter, 10... Hemisphere, 11... Cylinder as a guide member, 12, 14... Reference block.

Claims (1)

[Scope of Claims] 1. A reference block having three orthogonal concave planes that are orthogonal to each other and intersect at one point, and a point-like minimal contact portion at the tip, and the axis including this contact portion can be set in any direction. a measuring stylus, a hemisphere that is removably attached to the tip of the measuring stylus and has a spherical surface that can simultaneously contact three orthogonal planes of the reference block, and a point-shaped tip of the measuring stylus located at the center of the sphere. 1. An apparatus for a measuring method of a three-dimensional measuring machine, comprising: an adapter for detecting an origin, and a guide member for guiding a probe to be installed in the measuring device. 2. The device for a measuring method of a three-dimensional measuring machine according to claim 1, characterized in that the point-like minimal contact portion at the tip of the measuring stylus is shaped like a needle.