JPH0565007B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field of the Invention The present invention is a method for measuring a free-form surface of a three-dimensional three-dimensional surface press-formed from, for example, a thin metal plate, and calculating the normal to the surface to be measured and the distance to the surface to be measured. The present invention relates to the desired inclination detection device.

Conventionally, when measuring a free-form surface of a three-dimensional three-dimensional surface press-formed from a thin metal plate or the like and finding the normal to that surface, a fixed measurement axis is used to measure the bending that occurs on this measurement axis, and A sensor is attached to measure the tensile force, and a magnet is attached to the tip of this measurement axis. When the measurement axis is brought close to the surface to be measured during measurement, this magnet will be attracted to the surface to be measured. Therefore, a device that calculates the normal error from the magnitude of the output signal of each sensor generated, or a device that attaches three or more distance measurement sensors to the tip of a fixed measurement axis, and A device was used that calculated the normal error from the magnitude of the output signal generated by each sensor when the measurement axis was brought close to the sensor.

However, the former device requires particularly precise machining in order to obtain a structure of the measurement axis that can reliably measure the direction and magnitude of the bending force generated on the measurement axis. Due to the characteristics of the magnet attached to the tip, it is impossible to measure areas where the surface to be measured is sharply bent, or near cutting grooves and edges. In addition, in the latter device, three or more sensors are attached to the tip of the measurement shaft, so the shape of the tip of the measurement shaft becomes large, and as with the former device, the surface to be measured is bent sharply. It is impossible to measure the area where the cutter is cut, the cut groove, the edge, etc., and since there are a large number of sensors, amplifiers, etc. are required, which raises the cost. .

OBJECT OF THE INVENTION Accordingly, an object of the present invention is to configure the tip of the measurement shaft in a simple and compact manner so that the normal and The goal is to be able to measure distance.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides means for rotating a measuring shaft and outputting a signal corresponding to the rotational phase, and a predetermined amount of eccentricity from the center of rotation at the tip of the measuring shaft. A non-contact distance sensor is installed at the position of , and the measurement axis is brought close to the surface to be measured during measurement, and then the measurement axis is rotated to eccentrically rotate the distance sensor and make contact with the surface to be measured. The direction of the normal error, its magnitude, and the distance from the distance sensor to the surface to be measured are calculated from the output signal from the distance sensor that is generated proportionally according to the distance and the signal corresponding to the rotational phase. I have to.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a tilt detection device 1 according to the present invention is shown.
extends from the inside of the frame 2 along a center line A that is substantially perpendicular to the frame 2 and the surface to be measured S,
The measuring shaft 3 is supported by upper and lower bearings 13 on the frame 2 so as to be rotatable around the center line A. The measurement shaft 3 is equipped with a rotational drive gear 4 at its inner end.
This gear 4 is a drive gear 6 mounted on a drive shaft 5a of a motor 5 fixedly disposed within the frame 2.
It's meshing with each other. Further, a rotary encoder 7 is connected to the motor 5, and the rotary encoder 7 and the motor 5 constitute drive detection means, which detects the rotational position of the drive shaft 5a and sends a signal to the calculator 8. It is now output.

On the other hand, in the holder 3a at the tip of the measurement shaft 3, in order to measure the distance to the surface to be measured S at a position parallel to the center line A of the measurement shaft 3 and having a predetermined eccentricity R, An electromagnetic or capacitive distance sensor 9 is provided. This distance sensor 9
is fitted into the holder 3a at the tip of the measuring shaft 3 so that it does not move in the direction of its center line B and can freely rotate. The cable 10 is connected to the auxiliary shaft 11 inside the measurement shaft 3.
It is further fixed to a rubber bushing 12a of a bracket 12 fixed to the frame 2, passes through this, and is connected to the calculator 8 via an amplifier 9a. In addition, the auxiliary shaft 1
1 is rotatably supported by upper and lower bearings 14 with respect to the measurement axis 3, but the bracket 12
The cable 10 is supported by being prevented from rotating by the pin 11a with respect to the stopper 12b.

Effects of the Embodiment Next, the effects of the embodiment of the present invention configured as described above will be explained.

First, the inclination detection device 1 is brought close to the surface to be measured S as shown in FIG. Position it relative to the surface S to be measured. Note that the center line A of this measurement axis 3 coincides with, for example, a freely tiltable head axis of a processing machine. Thereafter, by rotating the motor 5, the measurement shaft 3 is rotationally driven via the drive gear 6 and the gear 4. In this case, the pin 11a and the stopper 11
b, the auxiliary shaft 11 remains stationary with respect to the frame 2 when the measuring shaft 3 rotates, and furthermore, the distance sensor 9 keeps the distance sensor 9 stationary when the measuring shaft 3 rotates due to the rigidity of the cable 10. In the measurement holder 3a at the tip, it makes one revolution in the rotation direction for one rotation of the measurement shaft 3, and
It rotates one rotation in the opposite direction. That is, the distance sensor 9 performs rotational movement around the center line A with a predetermined eccentricity R as a radius. This motion trajectory is
It is a circular orbit centered on the center line A within a plane perpendicular to the center axis A.

At this time, if the surface to be measured S is three-dimensionally parallel to a plane perpendicular to the center line A, the distance from the lower end surface of the distance sensor 9 to the surface to be measured S along the center line B is D is always constant during rotation of the distance sensor 9. However, if the measured surface S is not perpendicular to the centerline A, the distance D changes periodically during one rotation. The distance sensor 9 and amplifier 9a proportionally convert the change in distance D into an electrical analog quantity and send it to the calculator 8.

Therefore, the calculator 8 sequentially calculates the phase angle θ during rotation of the measurement shaft 3 based on the signal from the rotary encoder 7, and also calculates the target to be measured from the distance sensor 9 based on the magnitude of the signal from the distance sensor 9 at that time. Calculate the distance D to the measurement surface S and calculate the phase angle θ
and distance D are read in sequence to obtain a sine curve with the relationship shown in Figure 2a. Based on this relationship, the phase angle θmax and phase angle θmin that give the maximum amount Dmax and minimum value Dmin of the sine curve are determined, and this Distance at phase angle θo shifted by 90 degrees from phase angle value
Ask for Do. Note that the distance Do is the distance sensor 9
represents the average distance from to the measured surface S. here,
The phase angles θmax and θmin represent the inclination direction of the surface to be measured S, and the difference between them (Dmax−Dmin) represents the amount of inclination.

Theoretically, the inclination angle α can be determined by the following formula, assuming that the amount of eccentricity is R.

α=tan ^-1 [(Dmax-Dmin)/2R] In this way, the calculator 8 calculates the error between the center line A of the measurement axis 3 and the normal line of the surface to be measured S, that is, the direction of inclination and the inclination. Calculate the amount and distance D,
In order to correct this error, in other words, to make the center line A of the measurement axis 3 coincide with the normal line of the surface to be measured S, and to make the distance D the same, the normal line is The correction signals ±α, β and the distance correction signal ±N are outputted as outputs of the inclination detection device 1 to an attitude control device of a processing machine (not shown) or the like.

Now, FIG. 2b is a graph showing the same relationship as in FIG. 2a when there is a groove on the surface to be measured S, and the amount of inclination in this case is obtained by 2.times.(Dmax-Do).

Furthermore, Fig. 2c is a graph when there is no material in the section P because the measured surface S is the end of the material, and in this case as well, the amount of inclination is 2 x (Dmax -
Do).

FIG. 2d is a graph when the surface to be measured S is sharply bent upward on one side, and in this case, the amount of inclination is similarly obtained from 2×(Dmax-Do). .

Note that even if only the minimum value Dmin is obtained instead of the maximum value Dmax, the tilt direction and the tilt amount can be determined in the same manner.

Modification Example As a modification example of the embodiment described above, the distance sensor 9 is fixed to the tip of the measurement shaft 3, and a rotary connector is attached to the middle of the cable 10 connected to the distance sensor 9, so that the distance sensor 9 can be measured. The measuring shaft 3 may be rotated integrally with the shaft 3, and in this case, the tip of the measuring shaft 3 can be made even smaller. Further, the motor 5 and the rotary encoder 7 may be located outside the case 2. This facilitates assembly and adjustment.

Effects of the Invention As described above, according to the present invention, there is provided a means for rotating a measuring shaft and outputting a signal corresponding to the rotational phase thereof, and a means for rotating the measuring shaft to position the rotating shaft at a predetermined eccentricity position at the tip of the measuring shaft. and a distance sensor provided.
During measurement, the distance sensor is eccentrically rotated by bringing the measurement shaft close to the surface to be measured and rotating it, and the output signal from the distance sensor generated according to the distance to the surface to be measured and the rotational phase are adjusted. Since the direction and magnitude of the normal error are calculated from the corresponding signal, the tip of the measurement axis can be made small and its configuration is simple.
Even if the surface to be measured is sharply bent or has a cutting groove, or is at the edge of a material,
The inclination can be measured, and the manufacturing cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a main part of an embodiment of the inclination detection device according to the present invention, and FIG. 2 shows the rotational phase of the measurement axis obtained by the device of FIG. 1 in the case of measurement surfaces of various shapes. It is a graph showing the relationship between the angle and the distance from the distance sensor to the measured surface. 1... Tilt detection device, 2... Frame, 3...
Measuring axis, 4... Gear, 5... Motor, 6... Drive gear, 7... Rotary encoder, 8... Calculator, 9... Distance sensor.

Claims (1)

[Claims] 1. A measuring shaft rotatably supported around a center line substantially perpendicular to the surface to be measured, a drive detecting means for rotationally driving the measuring shaft and detecting its rotational phase, and a distance sensor that has a predetermined eccentricity and is supported by the tip of the measurement shaft so as to face the surface to be measured in a non-contact state and converts the distance to the surface to be measured into a distance signal; and a distance sensor that is output from the drive detection means. From the rotational phase signal and the distance signal output from the distance sensor, calculate the error between the center line of the measurement axis and the normal to the surface to be measured (inclination direction and amount) and the distance from the distance sensor to the surface to be measured. 1. A tilt detection device comprising: a calculator that outputs a signal for correcting this error; and a calculator that outputs a signal for correcting this error.