JPH0330083B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a method for measuring the outline (shape) of a workpiece from changes in the inclination angle of an arm when a stylus at the tip of the arm is moved to contact the workpiece. Regarding measuring equipment.

[Background Art] A stylus attached to the tip of an arm rotatably supported around a rotational fulcrum is brought into contact with the surface of the object to be measured, while the rotational fulcrum and the object to be measured are moved along a predetermined direction. A contour measuring machine is known that measures the contour of an object by relative movement and from changes in the inclination angle of the arm at this time, and is widely used for continuous measurement of three-dimensional objects.

In such a contour measuring machine, although the arm is moved in an arc, the angle of inclination of the arm is detected by detectors installed in the X and Y directions (see Figure 1), which are orthogonal to each other. It is. Therefore, for example, in FIG. 1, when the arm 1 is rotated by a predetermined angle around the rotational fulcrum 0, the stylus 2 at the tip of the arm 1 is moved by a dimension y in the Y direction.
Assuming that the displacement y in the Y direction is detected as is, on the other hand, the displacement y in the Y direction is detected as is.
The displacement δ in the direction is not detected at all since the rotation fulcrum 0 is immobile. That is, an arc error δ occurs.

Therefore, in order to achieve high-precision measurement with such a contour measuring machine, it is necessary not only to simply improve the machining and assembly accuracy of each component, but also to correct the arc error δ to minimize it.

There are two types of means for correcting the arc error δ: a mechanical method using a link mechanism, etc., and an electric method that operates the output signal of a detector. Yoni (Tokuko Showa 54-
26387), the circular arc error δ is expressed by the following formula δ=l−√ ² − ² ...(1), and using this formula (1) directly or by approximating this formula (1). There is a method which attempts to use the formula to cancel the arc error δ by calculating the amount of electricity corresponding to the length l of the arm 1 and the displacement y in the Y direction.

By the way, if an imaginary line in the X direction passing through the rotation fulcrum 0, in other words, an imaginary line indicating the movement trajectory of the rotation fulcrum 0 is a reference line T, then the movement of the rotation fulcrum 0 along the reference line T is The amount is detected as a displacement in the be. However, the accuracy and assembly of the arm 1 and stylus 2 during manufacturing, and the assembly accuracy of the mounting parts during replacement, and furthermore,
Due to the influence of the tightening force during fixation, the stylus 2
may be displaced from the reference line T.
Nevertheless, conventionally, there is no way to check whether the tip of the stylus 2 is accurately positioned on the reference line T, and even if it were to be checked, it would be done after assembly using other measuring instruments prepared separately. Because the measurement work was difficult, it was complicated, the work efficiency was extremely low, and it was difficult to confirm accurate deviations from the reference line.

Also, in order to allow the stylus 2 to contact and follow the surface of the object to be measured without any trouble, even if the tip of the stylus 2 is deviated from the reference line T by a distance H as shown in FIG. be. In such a case, the above equation (1) cannot be used as is, and even when the deviation dimension H is added (subtracted) to the displacement y in the Y direction, the tip of the stylus 2 is not the reference point. There is no way to easily check whether the position is exactly the deviation distance H from the line T.

Due to these circumstances, it has not always been possible to obtain highly accurate measurement results, even if the accuracy of processing and assembly of each component has been improved and the arc error has been corrected electrically or mechanically.

[Object of the Invention] An object of the present invention is to provide a contour measuring machine that can easily confirm the exact position of the tip of a stylus and can obtain highly accurate measurement results.

[Structure of the Invention] Therefore, the present invention provides an arrangement in which an arm having a stylus at its distal end is rotatably supported on an arm support about a rotational fulcrum at its proximal end, and the stylus is brought into contact with an object to be measured. A Y-direction detector detects the inclination angle of the arm when the object to be measured and the arm support are moved relative to each other in a predetermined direction. In the contour measuring machine equipped with the above-mentioned contour measuring machine, a deviation dimension inspection surface having a known deviation dimension from a reference line that is parallel to the relative movement direction and passing through the rotation fulcrum is provided, and a stylus is applied to this deviation dimension inspection surface. A deflection dimension detector is provided to detect the inclination angle of the arm when the arm is brought into contact with the arm, and the deflection dimension inspection body on which the deflection dimension inspection surface is formed is coupled to the arm support or the arm support. This object is achieved by attaching the stylus removably to a member of the stylus and making it possible to grasp the exact position of the tip of the stylus using the deviation dimension detector. Note that the term "deviation" here includes zero deviation.

[Description of Examples] Examples of the present invention will be described below based on the drawings.

FIG. 3 shows an embodiment of the contour measuring machine according to the present invention. In the figure, a support 12 is erected on a base 11, a lift box 13 is supported on the support 12, and the lift box 13 is It is designed to move up and down along the support column 12 by driving the handle 14. Further, the elevator box 13 is equipped with a drive motor 15 inside, and the rotation of the drive motor 15 is transmitted to the feed screw shaft 17 via the gear interlocking mechanism 16, and the amount of rotation of the feed screw shaft 17, that is, the amount of feed is X of rotary encoder etc.
It is designed to be detected by a direction detector 18. A nut member 19 is screwed onto the feed screw shaft 17 and is configured to move in the X direction as the feed screw shaft 17 rotates. An arm support 21 is connected to this nut member 19.
is adapted to move in the X direction together with the nut member 19.

The arm 1 is rotatably supported by the arm support 21 around a rotation fulcrum 0 on the base end side thereof,
Further, a stylus 2 is attached to the tip side of the arm 1. A Y direction detector 22 such as a differential transformer is provided in the middle of the arm 1, and the stylus 2
The displacement of the tip in the Y direction is detected.

A deviation dimension inspection body 23 is placed at an appropriate position on the elevator box 13.
is removably attached, and this deviation dimension inspection body 2
3 is formed with a deviation dimension inspection surface 24. The inspection surface 24 is oriented in the X direction so that the stylus 2 can come into contact with it, and the distance between the deviation dimension inspection surface 24 and the reference line T, in other words, the reference line T of the deviation dimension inspection surface 24. The deviation dimension H from is known.
The tilt angle of the arm 1 when the tip of the stylus 2 is brought into contact with the deflection dimension inspection surface 24 is detected by the deflection dimension detector, but in this embodiment, the Y direction detector 22 also serves as this. It is designed to be able to be used selectively for detecting deviation dimensions and for normal contour measurement. Y that also serves as this deviation dimension detector
The direction detector 22 detects a minute deviation ΔH of the tip of the stylus 2 from the deviation dimension H.

Further, a vise stand 25 is provided on the base 11,
The stylus 2 is movable in contact with the surface of the object to be measured 26 placed on the vice table 25, and the inclination angle of the arm 1 at this time is detected by the Y-direction detector 22. There is.

FIG. 4 shows the electrical system of this embodiment, and in the figure, the displacement x of the rotational fulcrum 0 detected by the The output signal of the Y-direction detector 22 is sent to the signal adjustment section 32, and the measurement/detection switching section 33 is connected to this signal adjustment section 32. 32, the amount of electricity E(y) corresponding to the amount of displacement y of the tip of the stylus 2 from the reference line T, and
Electrical quantity E (ΔH) corresponding to the minute deviation ΔH is selectively output.

Further, E(y) is input to the arc error correction means 31, and E(ΔH) is input to the deviation display device 34, where ΔH is displayed. Accordingly, it may be input to the arc error correction means 31 or the deviation dimension setting means 35. This deviation dimension setting means 35 determines the amount of electricity E(H) corresponding to the deviation dimension H.
are set, and the arc error correction means 31 inputs the electric quantities E(x), E(y), E(ΔH), E
E(x') and E(y') are calculated by performing necessary calculations on (H) using the above equation (1) or this approximate equation, and these are then recorded using an X-Y recorder, etc. Recorder 36
and the measurement results are recorded.

Here, an example of the calculation formula performed by the arc error correction means 31 is as follows.

E(x') = E(x) - E(δ) = E(x) - (E(l) - √(l) ² - () ² ) = E(x) - (E(l) -√ (l) ² −{()±((H)±())} ² )
...(2) E(y') = E(y)±(E(H)±E(ΔH))...(3) E(δ), E(l) in equations (2) and (3) are electric quantities corresponding to the circular arc error δ and the length l of the arm 1, respectively. In addition,
The arc error correction means 31 is not limited to an electric type, but may be a mechanical type using a link mechanism or the like, for example. In the case of a mechanical type, unless the deviation ΔH is directly used to correct the arc error, the stylus 2 may be adjusted or replaced to readjust ΔH within an allowable range.

This embodiment has the following effects.

Since a deflection dimension inspection body 23 having a deflection dimension inspection surface 24 and a deflection dimension detector (Y direction detector 22) are provided, the accurate position of the tip of the stylus 2, in other words, the stylus 2 You can check the exact length. Furthermore, simply by providing the deviation dimension inspection surface 24, the Y-direction detector 22, which is originally provided for contour measurement, can also be used as a deviation dimension detector. Therefore, the deviation ΔH from the deviation dimension H can be confirmed by simply adding an extremely simple structure.

Since the deviation dimension inspection body 23 is removably attached to the elevator box 13, the inspection surface 24 can be set to various values by replacing this deviation dimension inspection body 23 with one of various sizes. I can do it. Therefore, it is possible to check the exact deviation position of the tip of the stylus 2 from the reference line T (or the actual size of the stylus 2) according to the length of the stylus 2, and to check the type of stylus 2 according to the length. There is no problem in terms of measurement accuracy even if the number of units can be increased and the manufacturing of each unit is made easy.

Since the deviation ΔH from the set deviation dimension H is also used for the correction operation in the arc error correction circuit 31, accurate measurement results can be obtained from this point as well. In this case, especially when the arc error correction means 31 is of an electric type, the following effects can be obtained.

Either by aligning the tip of the stylus 2 with the reference line T or by shifting it by H,
Accurate measurement is possible because ΔH can be adjusted.

It is possible to perform automatic correction (see the broken line in FIG. 4) so that it is not necessary to manually adjust ΔH each time.

When the arc error correction means 31 is mechanical, the stylus 2 is moved while using the Y-direction detector 22 as a deviation dimension detector as an index when the tip of the stylus 2 is brought into contact with the deviation dimension inspection surface 24. can be replaced, etc., and subsequent measurements can be made without error.

Since the deviation dimension inspection body 23 is detachably attached to the elevator box 13, it can be removed from the elevator box 13 when the contour side of the object to be measured 26 is fixed.
It does not interfere with measurement.

The deviation dimension inspection body 23 is attached to the stylus 2, that is, the elevator box 13 that is connected to the arm support 21 and moves up and down together with the arm support 21, so that even if the height position of the arm support 21 changes, , stylus 2 and deviation dimension inspection object 23
The relative height position with respect to the deviation dimension inspection surface 24 does not change. Therefore, the height position of the arm support 21,
In other words, without measuring the height position of the rotational fulcrum of arm 1, the stylus 2 is moved to the deviation dimension inspection surface 2.
Since it is only necessary to make it come into contact with 4, high-precision inspection can be easily performed.

In implementation, the deflection dimension detector that detects the inclination angle of the arm 1 when the stylus 2 is brought into contact with the deflection dimension inspection surface 24 is not limited to the case where the Y direction detector 22 is also used; It may be provided separately from the detector 22. However, this Y direction detector 2
2 is also used, it is extremely convenient because it is possible to obtain both the deviation in the Y direction, which is the original measurement value, and the deviation ΔH from the deviation dimension H by simply operating the switching means 32.

Furthermore, the deflection dimension inspection body 23 is not limited to one that is removably attached to the elevator box 13, but may be detachably attached to the arm support 21. In other words, the deflection dimension inspection surface comes into contact with the stylus during inspection. It is sufficient that the deviation dimension inspection surface is provided in such a way that it is possible to do so, and the deviation dimension inspection surface does not come into contact with the stylus during measurement, that is, it does not interfere with measurement. However, if it is replaceable, there is no fear that it will interfere with the measurement of the object to be measured 26, and the deviation dimension H can be set to various values.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a contour measuring machine that can easily confirm the accurate position of the tip of the stylus and can obtain highly accurate measurement results.

[Brief explanation of drawings]

FIG. 1 is an enlarged side view of a stylus in an operating state, FIG. 2 is an enlarged side view of a stylus other than the above in a resting state, and FIG. 3 is a side view of a contour measuring machine according to the present invention. FIG. 4 is a side view showing the overall configuration of the embodiment, and FIG. 4 is a block diagram showing the electrical system of the embodiment. 1...Arm, 2...Stylus, 18...X
Direction detector, 21...Arm support, 22...Y
Direction detector, 23...Displacement dimension inspection object, 24...
deviation dimension inspection surface, 26... object to be measured, 31... arc error correction means, 33... measurement/inspection switching means,
35...Displacement dimension setting means, 36...Recorder.

Claims (1)

[Scope of Claims] 1. An arm having a stylus on the distal end side is rotatably supported on an arm support about a rotation fulcrum on the base end side, and the stylus is brought into contact with the object to be measured. A contour measurement device that detects the inclination angle of the arm with a Y-direction detector when the arm support and the arm support are moved relative to each other in a predetermined direction, and is equipped with an arc error correction means that corrects the arc error caused by the arc movement of the arm. In the machine, a deviation dimension inspection surface is provided with a known deviation dimension from a reference line that is parallel to the relative movement direction and passes through the rotation fulcrum, and a stylus is brought into contact with this deviation dimension inspection surface. a deflection dimension detector for detecting the inclination angle of the arm when the arm is tilted; A contour measuring machine characterized by being detachably attached to a member. 2. The contour measuring machine according to claim 1, wherein the deviation dimension detector also serves as the Y direction detector.