JPS612369A - Detector for displacement - Google Patents

Abstract

PURPOSE:To detect displacement by strain only in the direction of pull with high accuracy by fixing two OMEGA-shaped elastic plates, to which resistors for strain gages are fastened and which have different shapes, to a pedestal. CONSTITUTION:The ratio of the sensitivity of strain of the direction of pull to the direction of bending is increased extremely in order to easily compensate a detecting value by strain in the direction of bending regarding the OMEGA-shaped forms of an elastic plate 1 and a second elastic plate 4. A resistor 2a and a resistor 5a as strain gages are stuck to each curved surface section of the elastic plate 1 and the second elastic plate 4. Only a strain value of either of the direction of pull, the direction of compression or the direction of bending is detected by arithmetically operating a synthetic detecting value obtained from outputs from the strain gages.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a displacement detection device that detects displacement using a strain gauge. When displacements of are mixed,
The present invention relates to a displacement detection device that can correct the detected value of the strain cage and detect only the amount of displacement in multiple tensile directions with high accuracy.

[Prior art]

A conventional displacement detection device of this kind, which is a so-called Ω-shaped displacement detection device formed by attaching a strain gauge to a curved surface, is shown in FIG.

In the figure, (1) is an elastic plate, which is made of a highly elastic metal material such as perillum copper. (2) is a strain gauge, (2a) is this strain gauge (2)
A resistor with an ultra-fine electrical resistance wire such as nickel alloy, (2
Lead wire b) is drawn out from both terminals of the resistor (2, a) and connects the resistance value of the resistor (2a) to the side resistance circuit of the Wheatstone bridge, the oscillograph input, etc. (3) is a pedestal (not shown) fixed to the object to be measured whose displacement is to be measured. In addition, δ in the figure is the amount of strain in the above-mentioned tensile direction, the 0 point is the center of displacement in the bending direction, and R is the radius of curvature of the resistor (2 m) position centered on the 00 point of displacement in the bending direction. α represents the angle of change in the bending direction around the 0 point.

Next, the effect will be explained. First, the strain sensitivity of the strain gauge (2) is determined by the thickness of the elastic plate (1) to which the resistor (2a) is fixed, the elastic modulus E1, the section modulus I, and the radius of curvature of the curved surface forming the Ω shape. If the straight part is subjected to displacement in the bending direction, the center of displacement in the bending direction is 0.
is determined by the dimensions such as the radius of curvature R, etc.@Here, the strain sensitivity in tensile multi-directions determined by the above conditions is S11, the strain sensitivity in the bending direction is 82, and the resistor (2
Assuming that the strain value in a) is ε1 in the tensile direction and beam in the bending direction, it becomes εl−δ′ 81 8M−α−SZ.

Therefore, the strain value ε of the resistor (2a) when subjected to C strain in multiple tensile directions and strain in the bending direction at the same time is as follows: ε=εl+ε2=δ・St+α・S!・・・・・・(
1).

Since the conventional displacement detection device using an Ω-type strain gauge is configured as described above, even when it is desired to accurately detect only the displacement δ in the above-mentioned tensile direction, the strain in the bending direction expressed in equation (1) above can be detected accurately. Value α・S! is added to the detected strain value in the tensile direction, which has the disadvantage that it is difficult to detect displacement with high accuracy.

[Purpose of the invention]

The present invention has been developed in order to eliminate the drawbacks of the conventional ones as described above, and has two types of elastic plates with different shapes. The object of this invention is to obtain a highly accurate displacement detection device based on strain only in the tensile direction by forming an Ω shape in which a difference in strain sensitivity can be recognized in advance.

[Summary of the invention]

The present invention has been made to achieve the above objects,
The strain gauge is equipped with two elastic plates of different sizes, two strain gauge resistors fixed to each of these elastic machines, and a pair of pedestals for fixing both ends of the two elastic plates, respectively. The present invention provides a displacement detecting device that detects only strain values in any one of the tensile directions, the compressive direction, and the bending direction by calculating a composite detected value obtained from the output.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, (1) is an elastic plate, (2) is a strain gauge, (2a) is a resistor, (2b) is a beam #i+,
(3) is a pedestal, and shows a portion corresponding to the conventional example. (4) is the second glue/eleventh plate, (5) is the second strain gauge,
(5a) is the second resistor, (5b) is the second resistor (
5a) 1'+iA': This is the second lead wire from the child.

The Ω-shaped shape of the elastic plate (1) 4- and the second elastic plate (4) makes it easy to correct the detected value due to the strain in the bending direction, so that the strain sensitivity in the tensile direction and the bending direction can be easily corrected. It is desirable to increase the ratio by seconds.

As a matter of course, when the primary resistor (2a) and the second resistor (5a) are attached to the curved portions of the elastic plate (1) and the second elastic plate (4), they become resistors against strain. (2
a), the change in the electrical resistance value of each of the second resistors (5s) becomes i#: suitable condition.

Experimental values for determining the Ω-shaped shapes of the elastic plate (1) and the second elastic plate (4) are shown in FIGS. 2(A) and 2(B). For example, the straight part of the elastic plate (1) is 5 m, and the radius of curvature r is 35 m.

The straight part of the second elastic plate (4) is 35mm, the radius of curvature is r1
The sensitivities of each of the 5-sensitivity and water are 1183 μ for the elastic plate (1) for tensile strain, 1137 x/m for the second elastic plate (4), and 1137 x/m for the elastic plate (1) for strain due to bending.
is 582 μ/2°, and the second elastic plate (4) is 625 μ/2
The sensitivity ratio between the tensile and bending cases was approximately 2:1. However, in reality, the curved surfaces of the elastic plate (1) and the second elastic plate (4) overlap dimensionally, so
The linear portion L and the radius of curvature r of the elastic plate (1) and the second elastic plate (4) are 20 mm, 55 m, and 45 mg, respectively.
, 40 m, the sensitivity is 365 tt/m and 325 μ/2° for the elastic plate (1), and the sensitivity for the second elastic plate (4
) obtained 360μ/m and 345μ/2°, giving a sensitivity ratio of approximately 1:1.

Next, the effect will be explained. Based on the Ω-shaped dimensions of the elastic plate (1) and the second elastic plate (4) explained above with reference to the example, the tensile direction and bending direction of the resistor (2 &) and the resistor (5a) are determined respectively. Strain sensitivity is Sδ1+S
α1, Sδ1s8α, and the total strain values of the resistor (2a) and the second resistor (5a) are εI and ε2, respectively, then ε1−δ・Sδl+α・Sαl (2
)ε2=δ・Sδ2+α・Sα2 ・・・・・・(
3), so this (z), Sα1 and S of equation (3)
If α-value is determined as a low-value constant using experimental values, etc., α can be eliminated from both equations, so by performing appropriate calculations of εl and ε2, the accurate value of the strain amount δ in only the tensile multi-direction can be obtained. can get.

In addition, in the above example, an example was described in which the amount of strain δ in multiple tensile directions is accurately determined, but contrary to this example, the change angle θ in the bending direction is calculated without the influence of the strain ′jA, δ in multiple tensile directions. (2) above even when the distortion in the compression direction and the bending direction are mixed.

If the equation (3) is used, the same effect as in the embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, two Ω having different shapes
The resistor of the strain gauge is fixed to each of the two Ω-shaped elastic plates, and these elastic plates are integrally fixed to a pedestal connected to the object to be measured. By knowing the strain sensitivity of the strain gauge, it is possible to obtain a displacement detection device capable of detecting the amount of strain due to the combined output of two strain gauges, the tensile direction in multiple directions, the compression direction, or only one of the bending directions.

[Brief explanation of the drawing]

Fig. 1 is a front view of a displacement detection device showing an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between the shape of the displacement detection device in Fig. 1 and strain sensitivity, and Fig. 6 is a conventional displacement detection device. FIG. 3 is a front view of the detection device. (1): Elastic plate, (2) Nystrain gauge, (2m)
: Resistor, (2b) : Lead wire, (3) : Pedestal, (4) : Second elastic plate, (5) : Second strain gauge, (5m) : Second resistor, (5b) :Second lead wire.

Claims (1)

[Claims] The strain gauge is equipped with two elastic plates of different sizes, two strain gauge resistors fixed to each of these elastic plates, and a pair of pedestals for fixing both ends of the two elastic plates, respectively. A displacement detection device that detects only a strain value in any one of the tensile direction, compression direction, or bending direction by calculating a composite detection value obtained from the output.