JPS6241339B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distortion detection device. 2. Description of the Related Art In some cases, a load acting on a component of a machine or the like or a displacement is detected by detecting a strain in the component. Conventional strain detection devices detect strain in a beam by attaching a strain gauge such as a foil gauge to a beam that receives a lateral load, causing the beam to strain together, and detecting the strain in the strain gauge. . However, the amount of distortion in this case is relatively small;
Detection is difficult, and to compensate for this, increasing the output of the amplifier that amplifies the output from the strain gauge has the disadvantage of increasing noise.For this reason, even if the output of the amplifier is not increased, It is desired to develop a distortion detection device that can easily detect distortion.

This invention has been made in view of the above circumstances, and it is an object of the present invention to provide a strain detection device that can easily and reliably detect small deformations and displacements of an object to be measured. .

In order to achieve this purpose, the strain detection device of the present invention includes three beam members included in three parallel planes, and one end of the first beam member located in the center is connected to one end of the second beam member. the other end of the first beam member is rigidly connected to the other end of the third beam member, and a strain detection member is attached to the first beam member,
The present invention is characterized in that the load is applied to the third beam member in a direction parallel to the plane. Hereinafter, details of the present invention will be explained based on the drawings showing one embodiment.

In FIG. 1, reference numeral 1 denotes a strain detection device, and the strain detection device 1 includes a beam 2. As shown in FIG. The beam 2 is made of hardened steel such as SK steel or SCM steel, and includes three beam members included in three planes parallel to each other at intervals, that is, a first beam member 3, a second beam member 4, and a third beam member 5, one end 6 of the first beam member 3 located at the center is connected to one second beam member 4.
The first beam member 3 is rigidly connected to one end 7 through a connecting member 8, and the other end 9 of the first beam member 3 is rigidly connected to one end 11 of the other third beam member 5 through a connecting member 12. As a result, the beam 2 has an approximately S-shape as a whole.

Strain gauges 14a and 14 are arranged symmetrically with respect to the center point 13 on the upper and lower surfaces near both ends of the first beam member 3.
b, 15a, 15b are attached. The third beam member 5 is configured so that an external force 17 acts in a direction parallel to the plane.

In the strain detection device 1 configured in this manner, when the external force 17 acts on the third beam member 5, a moment due to the product of the magnitude and the length of the connecting member 12 acts on the first beam member 3. Then, the second
The undeformed first beam member 3 shown in FIG. 2B is deformed as shown in FIG.
Strain gauges 14a, 14b, 1
Since it is detected by 5a and 15b, the strain gauge 14
The outputs from a, 14b, 15a, and 15b are large, and the distortion of the first beam member can be easily and reliably detected without increasing the amplification degree of the amplifier. Therefore, if the magnitude of the external force 17 is configured to have a correlation with the displacement of the object to be measured, the distortion detection device 1 can easily detect the displacement of the object to be measured.

Next, the distortion detection device 1 configured in this way is
An example applied to measuring an inclination angle will be described. In FIG. 3, 21 is an object to be measured whose inclination angle is to be measured. The second beam member of the strain detection device 1 is attached to the object to be measured 21 with bolts 22, and the weight 23 is attached to the third beam member through the arm 24 made of a rigid body.
is rigidly connected to the lower part of the beam member 5. In this case, the length from the center point 13 to the weight 23 is L, and the mass of the weight is W. Now, suppose object to be measured 2
1 is tilted, the strain detection member 1 is tilted, as shown by the solid line in FIG. 3, and the weight 23 is also tilted accordingly. In this case, a tangential component force is generated due to the gravity of the weight on a virtual circle having a rotation angle of , and as a result, a moment acts on the first beam member 3. The same figure shows the stress at the gage attachment position, and the principal strain related to the gage output is given by σ _naxA and σ _naxB that occur on the surface. (Actually, the stress generation positions A and B mentioned above, and A' and B', which show stress states very similar to those, are 4.
σ _naxA = σ _p − (σ _b1 + σ _b2 ) σ _naxB = σ _p + (σ _b1 + σ _b2 ) In the above equation, each stress is calculated as σ _p , σ _b1 , and σ _b2 are approximately given below.

Note that τ shown in FIG. 3 is τ≈(W/h ₁ h ₂ )cosθ.

As a result, large distortions are exhibited as shown in FIG. 2b. This moment and strain are proportional to the inclination angle of the object to be measured 21, and have a length L and a mass W.
is proportional to. Therefore, the large strain of the first beam member 3 can be absorbed by the strain gauges 14a, 14b, 15a, 1.
By measuring with 5b, the inclination of the object to be measured 21 can be detected. Figure 4 shows a graph of the measurement results, and as sin≒ (within a range of <30°), the tilt angle and the gauge output are proportional, and in particular, the longer the arm length L, the more the gauge output. It is understood that the larger the value, the easier the detection (the reason for this is that σ _b2 takes on a large stress value when L becomes large). When detecting the maximum inclination angle of the object 21 to be measured and its direction in measuring the inclination angle of an inclined surface, set the x-axis and y-axis perpendicular to each other on the surface of the object 21 to be measured, and calculate the inclination angle of each. need to be detected. In this case, as shown in FIG.
Mount at right angles along the axis. In this case, the two distortion detection devices measure the tilt angle _yz around the x _p axis (the projection of the x axis onto the horizontal plane), the tilt angle _xz around the y _p axis (the projection of the y axis onto the horizontal plane), and is detected, and as ^shown _{in Fig} ^{. 6} , the maximum _inclination angle max _of the object to be measured ²¹ and _{its directions} /sin _xz ) _y = tan ^-1 (sin _xz /sin _yz ). (However, the x and y axes are _xz , _yz
The above equation is obtained based on the following equation obtained with reference to the drawing in FIG. 6.

What is shown in FIG. 7 is the distortion detection device 2 of the present invention.
1 is applied to a torque meter, and in this torque meter 31, the strain detection device 1 is used as a torque transmission member that connects an input shaft 32 and an output shaft 33. In this case, the third beam member 5 of the strain detection device 1 is attached to the input shaft 32, and the second beam member 4 is attached to the output shaft 33. Furthermore, in order to facilitate torque detection, the beam members 3, 4, and 5 are formed in an arc shape centered on the rotation axis.

In the torque meter having such a configuration, a parallel force acts on the third beam member 5 due to a change in input torque, and the moment generated thereby distorts the first beam member 3. Therefore, the strain gauge 14a,
By measuring this distortion using 14b, 15a, and 15b, the displacement of torque can be detected. In FIG. 7, reference numeral 34 indicates a sleeve 35 (the sleeve is fixed to the input shaft, and is attached to the input shaft during operation with torque) to prevent the strain detection device 21 from deforming in the radial direction due to centrifugal force during rotation. The phase is different from that of the output shaft.The two bearings in Fig. 7 have the role of holding and positioning the sleeve.)
This is a pin fixed to. When applied to this torque meter, as shown in FIGS. 7 and 8, by inserting the steel ball 36 into the center, the strain detection device 21 is pushed out to the left and right, and is in the state shown by the solid line. to the state shown by the chain line (Fig. 8). As a result, the force relationship in the axial direction generates stress that pinches the steel ball in the S-shaped detection portion, thereby minimizing vibration in the axial direction and making it possible to detect torque with less noise.

As is clear from the above description, the strain measuring device of the present invention effectively generates a large strain due to a moment in the beam member, and measures the large strain to determine the displacement of the object to be measured and the change in the applied force. Since the output of the strain gauge is large, it is possible to easily and reliably detect the displacement, etc., without increasing the amplification degree of the amplifier, which causes noise. .

[Brief explanation of the drawing]

FIG. 1 is a front view showing a strain detection device according to an embodiment of the present invention, and FIG. 2 is a front view of a strain detection device according to an embodiment of the invention.
FIG. 3 is a perspective view showing an example in which the strain detection device is applied to measuring the inclination angle, FIG. 4 is a graph showing the gauge output, and FIG.
The figure is a perspective explanatory diagram showing another example in which the strain detection device is applied to measuring the inclination angle, Fig. 6 is a perspective explanatory diagram showing the state of inclination of the object to be measured, and Fig. 7 is a perspective explanatory diagram showing another example in which the strain detection device is applied to the measurement of the inclination angle. FIG. 8 is a perspective view showing an applied example, and FIG. 8 is a perspective view showing a modification of the strain detection device when a steel ball is inserted in the center of the torque meter. DESCRIPTION OF SYMBOLS 1... Strain detection device, 2... Beam, 3... First beam member, 4... Second beam member, 5... Third beam member, 8, 12... Connecting member, 14a, 14b ,15
a, 15b...Strain gauge, 17...External force, 21
...Object to be measured, 23... Weight, 24... Arm, 31
...Torque meter.

Claims (1)

[Claims] 1 Comprising three beam members included in three parallel planes, one end of the first beam member located in the center is rigidly connected to one end of one second beam member, and the other beam members of the first beam member are rigidly connecting an end to an end of the other third beam member, and attaching a strain detection member to the first beam member;
A strain detection device characterized in that the strain detection device is configured to apply a load to the third beam member in a direction parallel to the plane.