JP2549289B2 - Maybe force detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multi-component force detector, and more particularly to an X-axis,
When a Cartesian coordinate system consisting of 3 axes of Y axis and Z axis is hypothesized,
A force acting on an arbitrary point on the object and a rotational moment are component force Fx in the X-axis direction, component force Fy in the Y-axis direction, component force in the Z-axis direction.
The present invention relates to a multi-component force detector that detects six independent component forces of Fz, a rotation moment Mx about the X axis, a rotation moment My about the Y axis, and a rotation moment Mz about the Z axis.

(B) Prior Art When an arbitrary external force is applied to an object, a maximum of six types of component forces (force and rotational moment) act on the object.
A load cell has been conventionally used as a means for measuring these component forces. However, the load cell is supposed to measure only the force in the simplest direction as an action system of force, and measures the force in that direction, and other component forces other than the force to be measured act. If you do, you cannot avoid the interference. Various technical considerations have heretofore been made to reduce the influence of other component forces. As one example, there is a multi-component force detector described in JP-A-57-118132. The configuration of this conventional example is shown in the front view of FIG.

That is, in the above-mentioned conventional example, the measurement side flange 80 and the fixed side flange 81 are arranged in parallel with each other by four (2
A pair of beams 82 to 85 are connected, and an imaginary three-axis orthogonal coordinate system of X, Y, Z with the Z-axis as the arrangement direction (direction orthogonal to the plate surface) of the two flanges 80, 81 , A component force Fx in the X-axis direction, a component force Fy in the Y-axis direction, and a rotational moment Mz about the Z-axis are strain gauges bonded to the beams 82 to 85 so as to be sensitive to the shear stress generated in the beams 82 to 85. 86
a-86c, 87a-87g, 88a-88c out of, for example, 87b, 87d, etc., and the other component force is a strain bonded to the beams 82-85 so as to be sensitive to the vertical stress generated in the beams 82-85. Gauge (eg strain gauge 87a, 87c, 87f for component force Fz
Etc.).

In addition, the transducer for detecting a multi-component force described in Japanese Utility Model Publication No. 54-21021 has a notch in order to make the spring constant different depending on the direction in the vicinity of both ends of four beams that elastically connect the measurement side flange and the fixed side flange. A plurality of pairs of strain gauges are attached to both ends of the beam and a bridge circuit for detecting a predetermined component force is formed by these strain gauges.

Further, in Japanese Utility Model Laid-Open No. Sho 58-169543, as shown in the perspective view of FIG. 22, a cross section that penetrates from one surface side to the other surface side in the middle of each square beam having two pairs of parallel surfaces. By forming a rectangular vertical hole 89 and a horizontal hole 90, four parallel beams 92a to 92d (however, 92d is not shown in the figure)
In this configuration, both shaft ends of the beam having large rigidity are integrally connected, and recesses 91 for stress concentration are formed at both ends of each parallel beam 92a to 92d, and the surface adjacent to the surface where the recess 91 is formed is formed. A four parallel side load cell formed by attaching strain gauges 93, 93 ... Is disclosed.

Now, here, when a force in the Z-axis direction is applied to the beams 82 to 85 shown in FIG. 21, or the parallel beam 92a in FIG.
When a force in the Z-Z direction is applied to ~ 92d, the beam 82 ~ 8
5 or considering the distribution state of the vertical stress generated in the parallel beams 92a to 92d (hereinafter, the beam 82 in FIG. 21 will be described as a representative), the stress is not observed in the cross section near both ends of the beam 82. It is constant, but its size is small, and at the joint between the measurement side flange 80 and the fixed side flange 81 and each beam 82, the effect is affected and the stress is disturbed (the stress distribution is not uniform) and the desired characteristics are obtained. Hateful. The cross section in the vicinity of the intermediate portion, which is separated from the vicinity of both end portions, has a substantially uniform distribution. Further, when the length of the beam 82 in the Z-axis direction is shortened, the stress distribution in the cross section in the vicinity of the intermediate portion is not uniform and has a complicated distribution state.

Thus, even if the beam 82 is somewhat short, and even if the beam 82 is long, the strain gauge attachment position is
If the distance from the end face of the beam 82 is not too great, it is not possible to obtain an electric signal that accurately corresponds to the force in the Z-axis direction, depending on the strain gauge. Because of this, beam 82
In the conventional multi-component force detector in which a strain gauge is attached to the side peripheral surface of the beam, it is necessary to lengthen the beam 82 in the Z-axis direction to some extent. However, if the beam 82 is made too long, a buckling phenomenon occurs in the beam 82 due to the applied force, and the beam 82 is easily affected by the force in the direction inclined from the Z axis, and the detection accuracy of the component force and the rotation moment is increased. There was a problem that it decreased. In addition, when the force detector is likely to be inserted in the force transmission system, the length of the beam 82 cannot be increased, and if it is increased, the object to be measured becomes large. It was

Further, in order to improve the detection sensitivity of the above strain by the strain gauge, it is desirable to make the beam 82 thin, that is, to make the outer circumference small, but if it is made thin, buckling easily occurs. I had a problem with.

As described above, in the above-described conventional multi-component force detector, in order to improve the detection accuracy of the component force, the lengths of the beams 82 to 85 and the parallel beams 92a to 92c are lengthened to a certain extent or more within a range where buckling does not occur. Inevitably, therefore, not only the force detector itself becomes large and heavy, but it can be applied to the object to be measured that needs to measure the force force using the force detector. There was a drawback that the range was limited.

(C) Object The present invention has been made to solve the above-mentioned drawbacks of the conventional force detecting device, and its object is to be small and lightweight, to prevent buckling, and to have a high capacity. It is to provide a multi-component force detector with extremely high measurement accuracy, which is capable of coping with the above and improved the separation ability of each component force and the detection sensitivity.

(D) Configuration Hereinafter, the gist of the present invention will be described in detail based on Examples.

FIG. 1 (a) is a front view showing the configuration of an embodiment of the multi-component force detector according to the present invention, and FIG. 1 (b) is FIG. 1 (a).
FIG. However, the strain gauge is omitted in FIG. 1 (b).

In FIGS. 1 (a) and 1 (b), 1 is a short cylindrical fixed-side flange whose lower end surface is fixed to an object to be measured and which has high rigidity, and 2 is a fixed-side flange 1 having a physical shape. The input side flanges 3 and 6 which are formed in substantially the same manner and are opposed to each other in a parallel state are beams serving as connecting beams in the shape of a quadrangular prism for elastically connecting the fixed side flange 1 and the input side flange 2, respectively. 7 to 10 are provided at substantially the central portions of these beams 3 to 6, and are cut out so that the outer circumference of the central portion is smaller than the outer circumferences of other parts, and the cross-sections thereof are beams 3 to 6.
Is a narrowed portion having a similar shape smaller than the lateral cross section of the strain-flexing element main body 11 including the fixed side flange 1 to the narrowed portion 10.
Is composed. In this flexure body 11, the beam 3
And 4 (or beams 5 and 6) are connected to each other, and a Y axis is taken to connect beams 3 and 6 (or beams 4 and 5) to each other, and an X axis is connected to connect fixed side flange 1 and input side flange 2. The Z axis is taken in the direction, the component forces in the X, Y, and Z directions of the axes are Fx, Fy, and Fz, respectively, and the rotational moments about the axes X, Z, and Z are Mx, My, and Mz, respectively. In addition, the distance between the facing end surfaces of the fixed side flange 1 and the input side flange 2 is H,
The distance between the centers of the beams 3 to 6 in the Y-axis direction is L ₁ , and similarly the distance between the centers in the X-axis direction is L ₂ . Incidentally, 12 to 51 (here, discontinuous numbers) are strain gauges attached to the beams 3 to 6 and the narrowed portions 7 to 10, and will be described in detail in the following description of the drawings.

2 (a) is an exaggerated diagram showing the flexure state of the multi-component force detector shown in FIG. 1 (a), and FIG. 2 (b) is a bending moment diagram. Note that Mmax represents the maximum value of the bending moment.

FIG. 3 is a sectional view taken along the line AA ′ of FIG. 1 (a) viewed from the fixed side flange side. In FIG. 3, the four side surfaces of each of the beams 3 to 6 and the narrowed portions 7 are shown.
With respect to each of the four side surfaces of 10 to 10, the upper side surface in the drawing is referred to as the a surface, and the respective side surfaces are sequentially clockwise in the b surface, the c surface, and the d surface.
I will call it a face. That is, each b-plane and d-plane is a side surface along the X-axis direction, and each a-plane and c-plane is a side surface along the Y-axis direction.
Denoted at 12 to 15 are strain gauges attached to each side surface of the constricted portion 7 in a direction in which the gauge axis coincides with the Z-axis direction (hereinafter referred to as "longitudinal direction"). It is attached so as to correspond to surfaces d to d. Similarly, 16 to 19 are on the a-plane to the d-plane of the narrowed portion 8, 20 to 23 are on the a-plane to the d-plane of the narrowed zone 9, and 24 to 27 are on the a-d plane of the narrowed zone 10. It is a strain gauge attached in the vertical direction. Incidentally, 15 ', 1
Reference numerals 7 ', 21', and 27 'are strain gauges each having a gauge axis described below attached in a direction substantially orthogonal to the Z axis (hereinafter referred to as "lateral direction").

FIG. 4 is an enlarged view showing an attachment state of two strain gauges having different gauge axis directions. In FIG. 4, 15 'is a strain gauge 15 on the d surface of the narrowed portion 7 which was touched previously.
It is a lateral strain gauge attached at a right angle to.
Therefore, the strain gauge 15 ′ is sensitive so that when the narrowed portion 7 extends in the Z-axis direction, the resistance value decreases according to the Poisson's ratio of the material of the beam 3, and the resistance value increases with compression. To be sensitive. The strain gauge 15 is configured so that the resistance value increases when the narrowed portion 7 extends in the Z direction and decreases when the compression portion 7 compresses. In addition, a pair of vertical and horizontal strain gauges as shown in FIG. 4 are attached to each of the b surfaces of the narrowed portions 8 and 9 and the d surface of the narrowed portion 10 in FIG. , FIG. 4 shows only the narrowed portion 7 as a representative thereof. Therefore, the other strain gauge 1
7 ′, 21 ′ and 27 ′ are the longitudinal strain gauges 17, 21, 2 respectively.
7 in pairs, the b-sides of the narrowed portions 8 and 9 and the d-side of the narrowed portion 10, respectively.
It is attached to the surface.

FIG. 5 is a cross-sectional view taken along the line CC ′ of FIG. 1 (a) viewed from the bottom surface side. In FIG. 5, the side surfaces of the beams 3 to 6 are called in the same manner as in FIG. 28 to 31 are on the upper surface of the beam 3 on surfaces a to d, 32 to 35 are on the upper surface of the beam 4 on surfaces a to d, and 36 to 39 are on the upper surface of the beam 5 on surface a to d.
Reference numerals 40 to 43 denote vertical strain gauges attached to the d surface and the a surface to the d surface of the upper end portion of the beam 6, respectively. Therefore, these strain gauges 28-43 are made to be sensitive to the expansion and compression of the a-plane to the d-plane of each of the beams 3 to 6 in the Z-axis direction, that is, to the bending stress of the beams 3 to 6. It is configured. However, the strain gauges 28 to 43 are all attached so that the gauge axis and the center line in the width direction of each side surface of each beam 3 to 6 coincide with each other. Therefore, for example, taking the beam 3 as an example (the same applies to the other beams 4 to 6), the a-plane extends in the Z-axis direction and c
When the surface is compressed in the Z-axis direction, the resistance of the strain gauge 28 increases and the resistance of the strain gauge 30 decreases, but the strain gauges 29 and 31 of the b-side and d-side have the axes of the gauge axes aligned with the neutral axis. Because it does, the resistance does not change. On the contrary, when the d-plane is expanded in the Z-axis direction and the b-plane is compressed, the strain gauge 31
The resistance of the strain gauge 29 increases and the resistance of the strain gauge 29 decreases, but the resistance values of the strain gauges 28 and 30 on the a-plane and the c-plane do not change because they are on the neutral axis.

FIG. 6 is a sectional view taken along the line BB ′ of FIG. 1 (a). In FIG. 6, the names of the four side surfaces of the beams 3 to 6 are the same as those in FIGS. 3 and 5, and will be omitted. 44
~ 47,48 ~ 51,52 ~ 55 and 56 ~ 59 are beam 3,
The strain gauges are vertically attached to the a-face to the d-face of the lower end portions of 4,5 and 6, respectively. The only difference between FIG. 5 and FIG. 6 is the difference between the upper and lower ends of the beams 3 to 6, and the other structure is substantially the same as that of FIG.

Incidentally, in FIGS. 3 to 5, FIGS. 1 (a) and 1 (b)
The same members as those in FIG.

7 to 13 are bridge circuits for detecting each component force and each rotation moment, FIG. 7 is a component force Fx, FIG. 8 is a component force Fy, and FIGS. 9 and 10 are rotation moments Mz. , FIG. 11 is a component force Fz, FIG. 12 is a rotation moment Mx, and FIG. 13 is a bridge circuit for detecting the rotation moment My.

In FIG. 7, 60 is the first side, 61 is the second side, and 62 is the third side.
Side, 63 indicates the fourth side, and 64, 64 'are input terminals, 65, 6
5'is an output terminal. When the bridge becomes unbalanced, the current flowing from the output terminals 65 to 65 'will be referred to as -i and the current in the opposite direction as + i. It should be noted that although these numbers are not particularly attached to FIG. 8 and subsequent figures, the same portions in the drawings are given the same numbers. Further, hereinafter, the bridge that detects the component force Fx is abbreviated as “Fx bridge”, and other component forces and rotational moments are also abbreviated similarly. Explaining the configuration of each side of the Fx bridge shown in FIG. 7, the first side is the strain gauge 28
The second side is a series branch of strain gauges 38 and 42, and the third side is a strain gauge 54,58.
Of the strain gauges 44 and 48 on the fourth side.

Similarly, for each side of the Fy bridge shown in FIG. 8, the first side is a series branch of strain gauges 31,43, the second side is a series branch of strain gauges 33,37, and the third side is a strain gauge. A series branch of 49, 53, and a fourth side is a series branch of strain gauges 47, 59.

9 and 10 are both Mz bridges, but FIG. 9 is composed of strain gauges attached to the upper ends of the beams 3 to 6, and FIG. 10 is also composed of strain gauges at the lower end. Therefore, Figure 9 below shows Mz bridge (top), and Figure 10 shows Mz bridge.
Bridge (bottom) is abbreviated respectively. Explaining the configuration of each side of the Mz bridge (upper) shown in FIG. 9, the first side is a parallel branch of the strain gauges 29 and 34, and the second side is the strain gauges 35 and 36.
Parallel branch, the third side is a parallel branch of strain gauges 39, 40,
The fourth side is composed of parallel branches of strain gauges 30 and 41. The configuration of each side of the Mz bridge (bottom) shown in FIG. 10 will be described. The first side is a parallel branch of the strain gauges 50 and 45, the second side is a parallel branch of the strain gauges 51 and 52, and the 3 sides are parallel branches of strain gauges 55 and 56, 4th side is strain gauge 4
It consists of 6,57 parallel branches.

In the Fz bridge shown in Fig. 11, the first side is a series branch of strain gauges 17 'and 21' in the lateral direction, and the second side is strain gauge 1
6,22 series branch, 3rd side is lateral strain gauge 15 ', 2
7'series branch, the fourth side is composed of strain gauges 12,26 in series.

The Mx bridge shown in Fig. 12 has a strain gauge 1 on the first side.
7,21 series branch, 2nd side is strain gauge 15,27 series branch, 3rd side is strain gauge 19,23 series branch, 4th side is strain gauge 13,25 series branch It is configured.

The My bridge shown in Fig. 13 has a strain gauge 1 on the first side.
6,12 series branch, 2nd side is strain gauge 22,26 series branch, 3rd side is strain gauge 14,18 series branch, 4th side is strain gauge 20,24 series branch It is configured.

FIG. 14 and FIG. 15 are diagrams showing the relationship between the resistance change of each strain gauge and the output when each component force acts in each bridge circuit shown in FIG. 7 to FIG. In the figure, an increase in the resistance of the strain gauge is indicated by a + sign, a decrease is indicated by a-sign, and when it does not change, it is indicated by 0. Also, 1 displays the output + i of the bridge circuit defined above,
1 corresponds to -i. Others will be described in detail later in the description of the operation.

Now, the operation of the present embodiment configured as described above will be described. When a component force Fx acts on the input side flange 2, the beams 3 to 6 receive a bending moment and the beams 3 to 6
At the respective upper ends (FIG. 5) of 6, the a-planes of the beams 3 to 6 are compressed in the Z-axis direction, and the c-planes thereof are extended in the Z-axis direction. Then, at the lower end portions of the beams 3 to 6 (FIG. 6), the a-planes of the beams 3 to 6 are elongated and the c-planes are compressed in the Z-axis direction. At this time, the distribution state of the bending stress generated in the beams 3 to 6 becomes maximum (Mmax) at both ends of the beams 3 to 6 as shown in FIG. It becomes zero. Therefore, the strain gauges 28, 3 are attached to the a and c planes of the upper and lower ends of the beams 3 to 6, respectively.
By attaching 0,32,34,36,38,40,42 and 44,46,48,50,52,54,56,58, the component force Fx can be detected as a bending stress, and the narrowed portion 7 Strain gauges 12 to 27, 15 ', 17', 21 'and 27' attached to a to d faces (Fig. 3) of 10 are bending stresses due to component forces Fx, Fy and Fz of beams 3 to 6. Can be insensitive to. Further, on the b-side and the d-side of the upper and lower ends of the beams 3 to 6, the center line in the width direction (X-axis direction) of the b-side and the d-side is the neutral axis. Strain gauges 29, 31, 33, 35, 37, 39, 41, 43 and 45, 47, 49, 51, 53, so as to match the above neutral axis.
By attaching 55,57,59, it can be made insensitive to the component force Fx.

With respect to the component force Fy, the same idea can be established by replacing the a-face and the c-face of the beams 3 to 6 with the b-face and the d-face in the case of the component force Fx.

When the rotation moment Mz acts on the input side flange 2,
Bending occurs in each of the beams 3 to 6 in the same manner as above, but unlike the component forces Fx and Fy, the bending direction is not parallel to the X axis or the Y axis, and is opposite to the rotation moment Mz at the upper ends of the beams 3 to 6. Tangential direction, the rotation moment at the lower end
The bending direction is the tangential direction that is the same as Mz. Therefore, at the upper ends of the beams 3 to 6 (FIG. 5), the c-plane and the d-plane of the beam 3, the a-plane and the d-plane of the beam 4, the a-plane and the b-plane of the beam 5, and the b-plane of the beam 6 are formed. The c-planes respectively compress, and the respective facing surfaces of the respective surfaces of the respective beams 3 to 6 expand.
Then, at the lower ends of the beams 3 to 6, a of the beam 3
Surface and b surface, b surface and c surface of beam 4, d surface and c of beam 5
The surface, the a surface and the d surface of the beam 6 are respectively compressed, and the facing surfaces of the respective surfaces are expanded. Here, to simplify the explanation, if L ₁ = L ₂ = L and the forces in the X-axis direction and the Y-axis direction applied to one beam by the rotation moment Mz are Fxm and Fym respectively, Therefore, after all, the rotational moment Mz can be detected as the bending stress in the X-axis direction and the Y-axis direction.

When the component force Fz acts on the input side flange 2, the beam 3 ~
The vertical stress concentrates on the narrowed portions 7 to 10 which are thinner than the other portions of 6. A small amount of stress is generated at the upper and lower ends of the beams 3 to 6, and their outputs are canceled by the bridge circuits formed by the strain gauges 28 to 59 attached to these parts. Therefore, it does not react to the component force Fz. Strain gauges 12-27 and lateral strain gauges 15 ', 17', 21 ', 2 are provided in the narrowed portions 7-10.
By attaching 7 ', the component force Fz can be detected with higher sensitivity.

When the rotation moment Mx acts on the input side flange 2,
Since the narrowed portions 8 and 9 generate compression and the narrowed portions 7 and 10 generate tensile vertical stress, the rotational moment Mx can be detected by the strain gauges 12 to 27.

In the case of the rotation moment My, the same concept as the rotation moment Mx is established only by replacing the narrowed portions 8,9 with 7,8 and the narrowed portions 7,10 with 9,10 in the case of the rotation moment Mx.

From the above-mentioned stress distribution state, six component forces Fx, Fy, Mx, My,
It can be seen that Mz can be detected.

Next, the operation of each bridge circuit that separates and detects each component force as an electric signal from these stress distributions will be described.

Now, when the component force Fx acts on the input side flange 2 in the direction shown in FIG. 1 (b), in FIG. 5 and FIG.
The resistance values of the strain gauges 28, 32, 54, and 58 decrease due to the compression of the a-plane and the c-plane in the Z-axis direction, respectively, and conversely, the strain gauges 38, 42, 44, and 48 receive tensile stress in the Z-axis direction. The resistance value increases. Then, each of the beams 3 to 5 in FIGS.
The resistance values of the strain gauges attached to the b surface and the d surface of 6 do not change because their positions are on the neutral axis.

Here, referring to the Fx bridge in FIG. 7, the resistance values of the strain gauges 28 and 32 forming the first side are both decreased, the second side is increased, the third side is decreased, and the fourth side is decreased. Both increase, and as a result, output terminal 65
The potential becomes lower than that of 5 ', and + i is output. That is, the component force Fx is detected.

Next, when the component force Fy acts on the input side flange 2, the strain gauges 31,43,49,53 have their resistance values reduced by the compression in the Z-axis direction. The resistance value increases, and as a result, in the Fy bridge of FIG. 8, the resistance values of the first side and the third side decrease and the resistance values of the second side and the fourth side increase. Therefore, the output is + i, and the component force Fy
Is detected.

Next, when the rotational moment Mz acts in the direction shown in FIG. 1 (b), the strain gauges 29, 34, 39, 40, 51, 52, 46, 57
Resistance value increases, strain gauge 35,36,30,41,50,45,5
The absolute value of 5,56 decreases, so in FIG.
The resistance values of the sides and the third side increase, the resistance values of the second side and the fourth side decrease, and the output of -i is obtained. In FIG.
Since the resistance values of the side and the third side decrease and the resistance values of the second side and the fourth side increase, the output of + i is obtained and the component force Mz is detected.
At this time, in the Fx bridge, strain gauges 32,4
The resistance value of 2,54,44 decreases, the resistance value of the strain gauges 28,38,58,48 increases, and as a result, for example, in the first side, the resistance value changes of the strain gauges 32 and 28 are mutually changed. Because it is the opposite,
Mutual resistance changes are canceled out, and finally the first to fourth sides
It means that there was no change in the resistance value on the side. Also in the Fy bridge of FIG. 8, the strain gauges 31,37,49,59 have reduced resistance values and the strain gauges 43,33,53,47 have increased resistance values, and the same canceling action as above is established. . Conversely, component force Fx
In the Mz bridge (top) and (bottom) shown in Fig. 9 and Fig. 10 when subjected to Fy and Fy, the Mz bridge (top) is verified as a representative. The gauges 29, 35, 39 and 41 have no change in resistance and strain gauge 3
The resistance value of 4,30 increases, the resistance value of strain gauges 36,40 decreases, and the change of the 1st side, 2nd side and 3rd side, and 4th side is exactly the same, so the potential between output terminals 65 and 65 ' Will remain balanced and the output will be zero. Also, when the component force Fy is received, there is no change in the resistance value of the strain gate 34,36,40,30,
The strain gauges 29 and 41 have increased resistance values, and the strain gauges 35 and 39 have decreased resistance values. Eventually, the Mz bridge (upper) maintains a balanced state and the output becomes zero. In other words, it can be seen that the component forces Fx, Fy, Mz can be detected separately from each other.

Next, the detection / separation of the component forces Fz, Mz, My, which is the main part of the present invention, will be described. When the component force Fz acts on the input side flange 2 in the direction (pulling) shown in FIG.
Vertical strain gauges 12 attached to a-d surfaces of ~ 10
Resistance value increases for all ~ 27 strain gauges in the lateral direction.
The resistance values of 15 ', 17', 21 'and 27' all decrease. Therefore, in the Fz bridge shown in FIG. 11, the first side and the third side
The side and the resistance value decrease, the resistance values of the second side and the fourth side increase and become + i output, and the component force Fz can be detected. In this case, the Mx bridge shown in FIG. 12 and the My bridge shown in FIG. 13 have the same resistance values of the strain gauges on all sides, so that the balance is maintained and the result is Output is 0. That is, the Mx bridge and the My bridge do not react to the component force Fz, and the component force Fz and the component forces Mx and My can be separated. Further, comparing the rate of change in resistance of the vertical strain gauge (for example, strain gauge 15) and the lateral strain gauge (for example, strain gauge 15 '), the rate of change in resistance value of the vertical strain gauge 15 is ± D. And stenosis 7-
When the Poisson's ratio ν of the material forming 10 is ν = 0.3, the rate of change K of the resistance value of the lateral strain gauge 15 ′ is K = ± 0.3.
XD. In other words, the rate of change of the strain gauge in the horizontal direction is smaller than that of the strain gauge in the vertical direction.

When the component force Mx acts on the input side flange 2 in the direction shown in FIG. 1 (b), the narrowed portions 8 and 9 receive a compressive force and the narrowed portions 7 and 10 receive a pulling force. Therefore, the vertical strain gauges 16-23
And the lateral strain gauges 15 'and 27' have reduced resistance,
The resistance values of the vertical strain gauges 12 to 15 and 24 to 27 and the horizontal strain gauges 17 'and 21' increase. Therefore, in the Mx bridge shown in FIG. 12, the resistance value decreases on the first side and the third side, and the resistance value increases on the second side and the fourth side.
The i output is generated and the component force Mx is detected. In this case, My
In the bridge, the strain gauges 12, 26, 14, 24 increase the resistance value, and the strain gauges 16, 22, 18, 20 decrease the resistance value. Are separated.

Further, in the Fz bridge, the resistance value increases on both the first side and the fourth side, and the resistance value decreases on both the second side and the third side. 22,26,1
2 is in the vertical direction, while the strain gauges 17 ', 21', 27 ', 15' forming the first and third sides are in the horizontal direction, the output terminals 65, 65 'are completely the same. It becomes a potential.

Next, when the component force My acts in the direction shown in FIG. 1 (b), the narrowed portions 7 and 8 in FIG. 3 are compressed and the narrowed portions 9 and 10 are pulled. Therefore, longitudinal strain gauges 12 to 1
9, horizontal strain gauges 21 ', 27' have reduced resistance, vertical strain gauges 20 to 27, horizontal strain gauges 15 ', 1
7'increases the resistance value. As a result, in the My bridge shown in FIG. 13, the resistance value decreases on the first side and the third side, and on the second side.
The resistance value increases on the side and the fourth side, and eventually the output of + i is obtained and the component force My is detected. At this time, in the Mx bridge shown in FIG. 12, the strain gauges 17, 15, 19, 13 decrease in resistance, and the strain gauges 21, 27, 23, 25 increase in resistance, and the increase and decrease cancel each other out. The equilibrium is maintained,
And Mx are separated.

Also in the Fz bridge, the increase and decrease of the resistance value cancels each other out so that the equilibrium state is maintained.
The component forces My and Fz are also separated. The above is summarized in FIGS. 14 and 15.

Therefore, as shown in FIGS. 14 and 15, FIGS.
By configuring the bridge circuit shown in the figure, it can be seen that the component force Fx, Fy, Mz, Fz, Mx, My of each detection target can be detected with high precision and high sensitivity without causing mutual interference between component forces. .

In this embodiment, since the narrowed portions 7 to 10 are provided in the middle portion of the beams 3 to 6, that is, in the vicinity of the position where the bending stress becomes zero, the component forces Fz, Mx, My in the Z-axis direction are divided into other portions. It has the advantage that it can be detected completely separated from the force, and that the above component forces Fz, Mx, My can be detected stably and with high sensitivity. In addition, the configuration in which the narrowed portion is provided has an advantage that the strain body main body can be reduced in size and weight. Further, by forming the beams 3 to 6 into a prismatic shape, the strain-flexing body 11 can be integrally formed by cutting or the like, and the manufacturing cost of the strain-generating body 11 can be reduced.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the invention.

For example, the bridge circuit that detects each component force is
A configuration as shown in FIG. 20 may be used. That is, component force
Fx is Fig. 16, component force Fy is Fig. 17, component force Mz is Fig. 18 (a),
(B), (c), (d), component force Mx is shown in Fig. 19 (a),
(B) and component force My may be configured as shown in FIGS. 20 (a) and 20 (b).

Also, for example, the d surfaces of the constricted portions 7, 8 and 10 and a of the beam 4
It is also possible to attach one strain gauge 15, 19, 27, 32 and 40, 43 to the surface and the a-plane and the d-plane of the beam 6, respectively. In this case, the component force Fz, Mx, My is the strain gauge 15,1
The component force Fx, Fy, Mz can be detected by the strain gauge 32,4 above.
It can be detected at 0,43. That is, it is possible to obtain a configuration in which the minimum of each component force can be separated and identified by three beams, two narrowed portions, and six strain gauges.

Further, a moment Mz is attached to the narrowed portions 7 to 10 so that the gauge axis is inclined at 45 degrees with respect to the Z axis, or a rosette type strain gauge is attached to the narrowed portions 7 to 10. It may be detected as the shear stress generated in 10.

Further, the cross-sectional shapes of the beams 3 to 6 and the narrowed portions 7 to 10 are not limited to square shapes, and the aspect ratio of the cross section may be appropriately selected according to the external force to be measured.

Further, although the Mz (lower) bridge is not used in the above-mentioned embodiment, the Mz (lower) bridge may be used instead of the Mz (upper) bridge. In this case, the output of the bridge is + i. Further, one output of the Mz (upper) bridge and the Mz (lower) bridge may be inverted and combined for use.

The strain gauges 12, 16, 22, and 26 are shared by the My bridge and the Fz bridge, but when it is necessary to electrically separate them, two strain gauges may be attached to each of the same parts. .

(E) Effects As described in detail above, according to the present invention, the device is small and lightweight, there is no risk of buckling, high capacity can be accommodated, and detection sensitivity can be improved. It is possible to provide a multi-component force detector with high measurement accuracy by making the detection sensitivity uniform and further improving the separation ability of each component force.

[Brief description of drawings]

FIG. 1 (a) is a front view showing the configuration of an embodiment of a multi-component force detector according to the present invention, FIG. 1 (b) is a bottom view of FIG. 1 (a), and FIG. 2 (a). ) Is a diagram for explaining the action in the embodiment, FIG. 2 (b) is a bending moment diagram, and FIG. 3 is a sectional view taken along the line AA 'in FIG. 1 (a). FIG. 4 is an enlarged front view showing an attachment state of two strain gauges having different gauge axis directions in a narrowed portion,
FIG. 5 is a sectional view taken along the line CC ′ of FIG. 1A, and FIG. 6 is a sectional view taken along the line BB ′ of FIG.
Figures 13 to 13 are circuit diagrams showing the configuration of a bridge circuit for detecting each component force. Fig. 7 is an Fx bridge, Fig. 8 is a Fy bridge, and Fig. 9 is an Mz bridge (above). Fig. 10 shows Mz bridge (bottom), Fig. 11 shows Fz bridge, Fig. 12 shows Mx bridge, Fig. 13 shows My bridge, and Figs. 14 and 15 show output components of each component and each bridge circuit. FIGS. 16 to 20 are circuit diagrams showing modified examples of the above bridge circuits.
Figure is Fx bridge, Figure 17 is Fy bridge, Figures 18 (a), (b), (c) and (d) are Mz bridges, Figures 19 (a) and (b) are Mx bridges, 20 Figures (a) and (b)
My bridge, Fig. 21 is a front view showing the configuration of the conventional example,
FIG. 22 is a perspective view showing the structure of another conventional example. 1 ... Fixed side flange, 2 ... Input side flange, 3-6 ... Beam, 7-10 ... Constricted part, 11 ... Strain body, 12-27 ... Vertical direction attached to constricted part Strain gauges, 15'17 ', 21', 27 '... lateral strain gauges attached to narrow holes, 28-43 ... beam strain gauges attached to the upper end, 44-59 ... beams Strain gauge attached to the lower end.

Claims (4)

(57) [Claims] 1. When a Cartesian coordinate system consisting of three axes of X-axis, Y-axis and Z-axis is hypothesized, a force and a rotation moment acting on an arbitrary point of an object are divided into an X-axis component force Fx and a Y-axis direction. Component of
Fy, component force Fz in the Z-axis direction, rotation moment M around the X-axis
In a multi-component force detector that detects six independent component forces consisting of a rotational moment My about the x and Y axes and a rotational moment Mz about the Z axis, both are thick and have high rigidity. The flange and the fixed side flange and the overall shape for elastically connecting the two flanges have a substantially prismatic shape, and four side surfaces of the intermediate portion are cut out so that the outer periphery of the intermediate portion is thinner than the outer periphery of other portions. When the strain body main body is formed from four connecting beams with narrowed portions formed therein and the direction in which the two flanges are arranged is the Z axis of the Cartesian coordinate system, the narrowing of the connecting beams. By the strain gauge attached to the portion so that the gauge axis matches the Z-axis direction, the component force Fz, the rotation moment Mx, and
My is detected as the vertical stress generated in each constriction, and the component forces Fx and Fy are applied to the connecting beams by a strain gauge attached so that the gauge axis matches the Z-axis direction at least near one end of the connecting beams. To detect the component force Mz as a bending stress generated in the connecting beam by a strain gauge attached to at least one end portion of the connecting beam so that the gauge axis matches the Z-axis direction. Probably a force detector characterized in that 2. The multi-component force detector according to claim 1, wherein each of the four connecting beams is orthogonal to the Z axis.
Perhaps a force which is arranged at a portion corresponding to each vertex of a virtual quadrangle formed by diagonal lines of the book, and adjacent side surfaces of each of the connecting beams are arranged along the X-axis and Y-axis directions. Detector. 3. The multi-component force detector according to claim 1, wherein the strain gauges for detecting the component force Fz, the rotational moment Mx and My are each of at least three of the connecting beams arbitrarily selected. Perhaps at least one force detector attached to any one of the four side faces forming the narrowed portion. 4. The multi-component force detector according to claim 1, wherein the strain gauges for detecting the component forces Fx and Fy and the rotational moment Mz are selected from at least two of the connecting beams arbitrarily selected. Perhaps a force detector that is attached to at least one adjacent side surface among the four side surfaces included in one piece and attached to any one side surface among the four side surfaces included in the other piece.