JPS595841B2 - Relative position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a relative position detection device for guiding a cutting device or the like along the circumference of an object such as a template.

The inventor has previously proposed an apparatus for detecting the relative position between the development center line and the vibrating element holding portion using a vibrating element, and the structure thereof will first be explained with reference to drawings. A vibration applying device, such as a DC motor 2, which applies vibration to the vibration system, is fixed to a fixed block 1 which is a part of the detector. An alternating current voltage is applied to the direct current motor 2 from an alternating current power source 3, and the motor shaft 4 reciprocates in accordance with the frequency of the alternating current voltage. The vibration system vibrated by the motor shaft 4 includes a center setting vibrating piece 5, a tightening jig 6 fixed to the motor shaft 4, and a vibrating piece □. The vibrating piece 7 resonates in the primary resonance mode shown in FIG. 3 or in the secondary resonance mode shown in FIG. 4 depending on its shape, material, and dimensions, and the position of the free end of this resonating vibrating piece 7 is detected. object 14
If it comes too close to the object, it will contact only this object, and if it moves away from the object, it will contact only the amplitude limiting plate 15, and if the vibration center position of the fixed side of the vibrating piece 7 is in the center of both, the free end It is possible to detect the relative position by detecting an electric signal generated by contacting both of the two alternately and evenly. That is, the relative position of the center of the shaft of the DC motor with respect to the groove surface or its center line, and thus of the fixed block 1 and the gas cutting torch, welding torch, etc. connected thereto, is detected. The contact of this vibrating piece is electrical circuit 9, 1
0 is electrically detected, and the signal allows a detector, and by extension a welding torch, etc., to follow and guide the groove center line 13 of the base material 8. Let us now consider the operating principle of the device according to the present invention. The vibrating piece that functions as a sensor for this device is cantilevered and in resonance.

This resonance state refers to the natural frequency F of the vibrating piece when an external force that contributes to vibration is applied to the vibrating piece as excitation energy. A state in which vibration is caused by applying excitation energy at the same frequency as . In this state, even a very small amount of excitation energy is converted into vibration energy, so the amplitude increases over time.
Becomes infinity. However, in an actual device, there is energy loss due to air resistance during vibration, deformation distortion of the vibrating element, etc., so the device enters a steady state at a certain maximum amplitude W (Figure 9), and thereafter vibrates at the amplitude W. That will happen. Co-progressive frequency F of a cantilevered vibrating piece.

is proportional to the square root of the value shown below. FoocVi...
・・・・・・・・・・・・(1)＝−・・・・・・・・・
(2) When a cantilevered vibrating piece resonates, even if the vibration energy received by the vibrating piece is small, its free end swings greatly, but if the frequency deviates even slightly from the resonant frequency, the amplitude quickly decreases to O. I get closer.

For example, a device having a resonance amplitude of about 2011 11 times will become only about 2 mm if it deviates from the resonance frequency. Although the time is extremely short, the transient phenomenon from the start of vibration to the steady state of the maximum amplitude W is as shown in FIG. 9.

Now, assume that the center of vibration is the origin 0, and that the position of the vibrating piece at a certain time t1 is -X, (velocity=O).

When the period of vibration is T (Sec), since I/FO=T, time 1/2×1/FO from time t1, that is, the vibrating piece after half a period is X, +f(X,)=X2 come to the position. Here, f(x) is converted into vibrational energy.

This is the amount of increase in the amplitude of the vibrating piece due to excitation energy. As mentioned above, even if the excitation energy is constant, there is air resistance, etc., so f(x) is a decreasing function.Furthermore, 1
The vibrating element after /2F0 is -X3=1 (X2+f(X2))
come to the position.

Similarly, the amplitude of the vibrating element reaches the maximum amplitude W while increasing the amplitude of 2f(Xn) by receiving the reciprocating excitation energy per cycle as vibration energy. During resonance, the free end of the vibrating piece vibrates at the maximum amplitude W due to the balance between the excitation energy received from the motor etc. and the energy loss due to air resistance, etc., but as shown in Figures 8 and 10, the amplitude If there is a restricting surface (for example, the left side groove surface 8a) at the position (-x1) that restricts the
It vibrates in a resonance-like manner while maintaining its amplitude.

This is due to the following reasons. At the moment when the vibrating piece vibrating with the amplitude W hits the limiting surface 8a, the energy of the vibrating piece is consumed as energy for pushing the limiting surface 8a, thermal energy, etc. Then, when the vibrating piece separates from the limiting surface 8a, it receives excitation energy again, and X2=X1+f(
Come to position X1). That is, the vibrating piece, which was resonating with the amplitude W in a steady state, shifts to a transient state from the moment it hits the limiting surface 8a until it resonates. However, after one cycle, it hits the limiting surface 8a again, and the excitation energy for one round trip is again consumed as thermal energy, etc., and the same movement is repeated thereafter.

This state can be said to be a vibration similar to a resonance state with an amplitude of W1-X1+X2. In such resonance-like vibrations, the origin 0 does not exist at the center of the amplitude W with mathematical accuracy, but moves by the amount of excitation energy (i.e., X2 - X1), and this appears as a measurement error. Since the excitation energy itself is extremely small, this error is so small that it can be ignored in measurement.

Further, since the contact between the surface 8a and the vibrating element is a contact that only consumes the excitation energy for one round trip, the contact is almost non-contact. Next, Figure 8, Figure 10
A method of detecting the center line between opposing surfaces, for example, the center line of a welding groove, will be specifically explained with reference to the drawings.

When the free end contacts the left groove surface 8a and resonates as shown in FIG. 8, the other free end position 70 shown does not come into contact with the right groove surface (another object) 8b.

Therefore, it is possible to detect that only the left side groove surface 8a is in contact and extract it as an electrical signal. Similarly, if the fixed point 4 comes too close to the right groove surface 8b, it can be taken out as an electrical signal that it is too close to the right groove surface. When the fixed point returns to the center plane (CL plane) of the groove, the amplitude of the free end 70 becomes large as W because it resonates, and it alternately contacts both groove surfaces 8a and 8b at the resonant frequency. However, by extracting this as an electrical signal, it is possible to detect that the fixed point 4 is always within the center plane of the groove.

This is summarized in Table 1. By utilizing the characteristics of such a resonating vibrating piece, this vibrating piece can be used as a sensor to determine the relative position of the center of the shaft of the DC motor and the relative position of the stationary block 1 and the welding torch connected to it with respect to the center line of the groove surface. It is something to detect.

This contact between the vibrating pieces is electrically detected by electrical circuits 9 and 10, and the signals make it possible to follow the groove center line 13 of the base material 8 with the detector, and hence with the welding torch, and guide it to an upright position. Further, since the vibrating piece vibrates at 50 cycles (or 60 cycles), the welding nozzle or the arc can be easily seen through the vibrating state of the vibrating piece. Such a device is particularly useful for detecting the centerline of a weld groove.

On the other hand, there is a demand for templates and the like to follow the periphery and have low contact resistance. Conventionally, in such cases, a contact rod with a spherical end was brought into contact with the periphery of the template, and this was transmitted as a mechanical or electrical signal to the detector. However, this results in a large contact frictional resistance, which poses a problem from an accuracy standpoint. An object of the present invention is to propose a device that makes contact with a template, etc., and detects the relative position with respect to the template with low contact resistance.

In short, the present invention is characterized in that it is a device that brings a vibrating piece that almost resonates into contact with an object, converts this contact into an electrical signal, and guides a detector.

Further, the present invention is characterized in that the vibrating element is provided with an amplitude limiting member that applies resonance or vibration at a frequency close to resonance while limiting the end amplitude of the vibrating element to a desired amplitude in order to improve detection accuracy. This invention will be explained with reference to the drawings.

The vibrating piece and the vibration imparting device are similar to those shown in FIGS. 1 and 2. In FIG. 5, the vibrating piece 7 is vibrated at a constant amplitude, and the surface of the object, for example, the periphery 14 of the template 14, is vibrated.
The copying operation is performed depending on the presence or absence of contact with a.

FIG. 6 is intended to limit the amplitude at the end of the vibrating piece to a constant width, and shows an amplitude limiting member 15 developed from the fixed block 1 that supports the vibrating piece 7.

Even when the vibrating piece is in a state close to resonance, the amplitude at its end is easily limited by the amplitude limiting member 15 as shown in FIG. The experimental results show that in the case shown in Fig. 5, the change in the voltage applied to the DC motor 2 is small, that is, it is important to keep the electrical energy application steady, that is, to maintain a favorable resonance state, in order to improve accuracy. It was confirmed that this is desirable.

It has been confirmed through experiments that when the amplitude limiting member 15 is provided as shown in FIG. 6, the amplitude of the vibrating element is less affected by changes such as fluctuations in the applied voltage and the accuracy is improved.

In addition to vibrating the vibrating element in a hanging state as shown in FIGS. 5 and 6, when the vibrating element is horizontal, it is possible to trace and detect the concavity of the object relative to the horizontal plane.

By implementing this invention, the relative position of the object and the detector can be easily detected, and the relative position can be detected with high accuracy by tracing the peripheral edge of the template and also tracing the irregularities in the vertical direction of the surface. It has various effects such as.

[Brief explanation of the drawing]

Fig. 1 is a front view of a detector using a vibrating element, Fig. 2 is a side view thereof, Fig. 3 is a vibrating element showing the primary resonance mode, and Fig. 4 is a vibrating element showing the state of the secondary resonance mode. FIG. 5 is a drawing showing the state of tracing detection of the template according to the present invention, FIG. 6 is a drawing showing the state of tracing detection when using an amplitude limiting plate,
Figure 7A is a side view of the cantilever beam, Figure 7B is Figure 7AO)I
-1 cross-sectional view, Figure 8 shows the amplitude W of the free end of the vibrating element when it resonates.
9 and 10 are diagrams illustrating the operating principle of the present invention. 1... Fixed block, 2... DC motor, 3... AC power supply, 7... Vibration piece,
15...Amplitude limiting member.

Claims (1)

[Claims] 1. A detection device equipped with a vibrating piece whose maximum resonance amplitude is larger than the distance between opposing objects is placed between two objects, and the vibrating piece is excited at a resonant frequency, and the vibration piece is free to move. In a detection device that detects the relative position of the vibrating element and the object based on a signal generated when an end comes into contact with one or both of the two objects, an amplitude limiting member is extended from the detector; A relative position detection device, wherein one of the objects is one of the objects.