JPH04178509A - Measurement method for coordinate measuring machine - Google Patents

Abstract

PURPOSE:To perform reliable measurement by mounting a spherical stylus on a probe body displaceably in a three-dimensional direction, locating a filler between the body and the stylus when the stylus is brought into contact with the surface of an object to be measured to measure a coordinate, and correcting the measuring value of the stylus by means of a bending amount of the filler. CONSTITUTION:In a coordinate measuring machine employing a three-dimensional probe, a probe itself is also movable in three axial directions independently away from movement in the directions of an X-, an Y-, and a Z-axis of a probe holding part. When the surface of an object 50 to be measured is measured in the direction of, for example, the Z-axis by means of a coordinate measuring amount having a probe 52, a stylus 54 of the probe 52 is brought into contact with the surface of the object 50 to be measured and a measuring force F in the direction of the Z-axis is exerted on the stylus 54, and in this case, a reaction force is sometimes exerted in three axial directions. Thus, a filler 56 is located between the probe 52 and the stylus 54, and by bending the filler, a reaction force is prevented from generation. The filler 56 is also located in a similar manner described above in the direction of the Y-axis and the direction of the X-axis, and a true measuring value is produced from the stylus 54.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a measuring method using a coordinate measuring machine.

[Conventional technology]

As a device for measuring the coordinates and shape of the surface of an object to be measured, a spherical stylus is held in the probe body via a feeler so that it can be displaced in three-dimensional directions (X, YSZ axis directions), and the stylus is brought into contact with the surface of the object to be measured. There is a coordinate measuring machine that measures the coordinates and shape of a measured object.

There are two types of coordinate measuring machines: one in which the measuring force of the probe can be varied and the other in which the measuring force is applied by displacement. A coordinate measuring machine that can vary the measuring force of the probe is used to adjust the measuring force from the state in which the stylus 12 of the probe 10 is in contact with the surface 14 of the object to be measured as shown in FIG. 4(A).
As shown in Figure (B), a measuring force is applied to the probe 10, and the amount of displacement at that time is read with the probe scale 16.

Graph 1 shows correction coefficients regarding the measuring force F and the displacement amount of the probe 10, which are determined in advance by the least squares method.
8 (see Figure 5) to probe 1 corresponding to the measuring force F.
A correction value of 0 is obtained and the displacement amount of the probe 10 is corrected.

In addition, a coordinate measuring machine that applies measuring force by displacement uses a stylus 22 of a probe 20 as shown in FIG. 6(A).
6 (B) from the state in which the
), the measuring machine main body is moved, and the displacement of the measuring machine main body is read from the main body scale 26, and the displacement of the probe is read from the probe scale 28. A graph 30 (
(See FIG. 6), a correction value is determined for the probe 20 corresponding to the displacement of the measuring instrument body, and the amount of displacement of the probe 20 is corrected.

[Problems to be Solved by the Invention] By the way, some objects to be measured have, for example, a spherical surface, and in this case, the direction of deflection of the tweeter changes depending on the measurement direction of the probe 12, so that the deflection direction of the tweeter changes only in one dimension. Not limited to.

However, conventional methods have only corrected the measurement direction of the probe 10, that is, the one-dimensional direction, so there is a problem that the surface shape of the object to be measured cannot be accurately measured.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a measuring method using a coordinate measuring machine that can accurately measure the surface shape of an object to be measured.

[Means to solve problems]

In order to achieve the above object, the present invention has a stylus attached to a tweeter of a probe that is attached to a coordinate measuring machine body and can be displaced in three-dimensional directions of X, Y, and Z axes to measure the shape of an object to be measured, etc. In the measuring method of the coordinate measuring machine, the amount of deflection of the tweeter per unit force in the X, Y, and Z axis directions is determined in advance, and the slirus is pressed against the object to be measured with a predetermined measuring force. Move the probe in the measurement direction to obtain the measured value of the object to be measured, and calculate the deflection amount of the tweeter at the time of the measurement from the measured value and the deflection amount of the fee per unit. The method is characterized in that the measured value is corrected.

[Effect]

According to the present invention, when measuring the shape of an object to be measured such as a sphere having a curved surface in a three-dimensional direction with a predetermined measuring force,
The amount of deflection of the tweeter at the time of measurement is determined from the measurement force and the amount of deflection of the tweeter per unit in the three axis directions determined in advance, and the value obtained by correcting the measured value at the time of measurement using this amount of deflection is calculated as Shape measurement value.

〔Example〕

A measuring method using a coordinate measuring machine according to the present invention will be explained below with reference to the accompanying drawings.

In the present invention, a so-called three-dimensional probe (electronic probe)
We will explain the measurement method using a coordinate measuring machine using Here, the three-dimensional probe means that the probe holding part is
This refers to a probe that is movable in the three axes of X, Y, and Z independently of being moved in the three axes of Z.

As shown in FIG. 1, the object to be measured 5 is formed into a spherical shape.
When measuring a 00 surface in the Z-axis direction with a coordinate measuring machine equipped with a probe 52, the stylus 54 of the probe 52 is brought into contact with the surface of the object to be measured 50, and a measuring force F in the Z-axis direction is applied via the tweeter 56. It is attached to the stylus 54.

In this case, since the stylus 54 is in contact with the spherical curved surface of the object to be measured 50, the stylus 54 is
In some cases, the reaction force acting on the tweeter 56 is deflected in the three axial directions of the X, Y, and Z axes, and the tweeter 56 is deflected in the three axial directions of the x, Y, and Z axes. If this amount of deflection is expressed as (dxzSdyz, dzz), the amount of deflection dxz in the X-axis direction can be determined from the graph 60 shown in FIG. 2 from the displacement of the measuring instrument body.

The graph 60 shown in FIG. 2 has the displacement Mx of the measuring machine main body on the vertical axis.
, the displacement Pxz of the probe 52 is plotted on the horizontal axis, and the measuring force is F.
It is determined by the least squares method from the amount of deflection of the probe 52 in the X-axis direction when measured with each measuring device by varying the values 1, F2, F3, F4, and Fs.

Further, the deflection amount dyz in the Ys11 direction and the deflection amount dzz in the Z-axis direction can also be determined by the method described above.

Furthermore, the amount of deflection in the three-axis directions (tixySdV'J, dzy) when the measuring mold acts in the Y-axis direction, and the measuring force F acting in the X-axis direction as shown by the imaginary line in Figure 1. The amount of deflection in the three axial directions (dxx, d y x,
d z x) can also be obtained in the same way as when the measuring force F acts in the X-axis direction described above.

Therefore, if the measured displacements of the probe in the X and YSZ axis directions are Px and pySPz, respectively, then the probe displacement (qx, qy, qx) after correcting the amount of deflection of the feeler 56 is
and the measured displacement of the probe (Px, PySPz) have the relationship shown in equation (1).

Furthermore, the parallelism between the probe 52 and the measuring machine body can be corrected using equation (1).In other words, when the probe 52 is set at an angle to the measuring machine body as shown in FIG. Let the displacement of the measuring machine body in the Y-axis direction be YM, and the displacement of the probe in the Y-axis direction at this time be YP, ,
When the displacement in the X-axis direction is xPl, the correction coefficients ciyy and dxy in the Y-axis direction and the X-axis direction are YM.

XP.

It is expressed as

In addition, the displacement of the measuring machine body in the X-axis direction is χM2, and the displacement of the probe in the X-axis direction at this time is XP2, YM
If the displacement in the direction is YP2, the correction coefficients dxx and dYX in the X-axis direction and the Y-axis direction are M 2 dxx=−XP.

YP.

It is expressed as

Although the above-mentioned correction coefficients have been explained in the case of two axes, X# and Y axes, the correction coefficients can be obtained in a similar manner in the case of three axes, xSy and Z axes. By substituting this correction coefficient into the above-mentioned equation (1), the parallelism between the probe 52 and the measuring instrument body can be corrected. Therefore, the time required to set the probe 52 in the measuring instrument body can be shortened.

Further, since the internal squareness of the probe 52 can be corrected using the same concept, there is no need to adjust the internal squareness using an adjustment mechanism inside the probe 52 as in the conventional case.

[Effect of C-hook] As described above, according to the measuring method of the coordinate measuring machine according to the present invention, the measured value of the probe can be corrected even if the feeler is deflected in any direction in the three-dimensional space. , it is possible to measure by pointing the probe in any direction, and even if the length of the feeler becomes longer and the amount of deflection increases, highly accurate measurement is possible.

Further, since it is not necessary to strictly adjust the squareness inside the probe by three-dimensional correction, it is possible to eliminate the squareness adjustment by an adjustment mechanism inside the probe.

Furthermore, since there is no need to accurately align the probe parallel to the measuring machine when attaching it to the measuring machine, the probe can be easily attached and detached, and the structure can be simplified since the accurate parallel alignment mechanism can be removed. I can do it.

[Brief explanation of drawings]

Fig. 1 is an enlarged view of the main parts of the coordinate measuring machine according to the present invention, Fig. 2 is a graph used for correction of the coordinate measuring machine according to the present invention, and Fig. 3 is a graph for parallel alignment of the coordinate measuring machine according to the present invention. Graphs used for correction, Figure 4 (A), (B) and Figure 6 (A)
, (B) are enlarged views of main parts of a conventional coordinate measuring machine, and FIGS. 5 and 7 are graphs used for correction of the coordinate measuring machines shown in FIGS. 4 and 5. 50... object to be measured, 52... probe, 54...
...Stylus, 56...Feeler.

Claims (1)

[Claims] (1) A coordinate measuring machine that measures the shape, etc. by bringing the stylus attached to the feeler of the probe, which is installed in the main body of the coordinate measuring machine and can be displaced in the three-dimensional directions of the X, Y, and Z axes, into contact with the object to be measured. In the measurement method, the amount of deflection of the feeler per unit force in the X, Y, and Z axis directions is determined in advance, the sliver is pressed against the object to be measured with a predetermined measuring force, and the probe is moved in the measurement direction. A measured value of the object to be measured is determined, an amount of deflection of the feeler at the time of the measurement is determined from the measured value and the amount of deflection of the feeler per unit, and the measured value is corrected by the amount of deflection. How to measure using a coordinate measuring machine.