JP4464005B2 - High rigidity load transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-rigidity load transducer, and more specifically, a strain gauge is attached to a strain-generating portion of a strain-generating body having a substantially rectangular plate shape, and is formed at both longitudinal ends of the strain-generating body. A so-called link-type load converter that detects the tensile load applied to the load receiving circular hole and obtains an electrical signal, for example, an overload prevention load converter used in industrial machines such as cranes, The present invention relates to a high-rigidity load transducer suitable for a load cell for detecting the wire tension of structures such as ships, shipboard structures, bridges, and dome ceilings.
[0002]
[Prior art]
As the link type conventional load transducers described above, load transducers such as the first conventional example shown in FIGS. 6 and 7 and the second conventional example shown in FIGS. 8 and 9 are frequently used.
That is, the load transducer according to the first conventional example shown in FIGS. 6 and 7 has the load receiving circular holes 2 and 3 at both ends of the strain generating body 1 made of a metal elastic body having a substantially rectangular plate shape. The strain detection circular hole 4 is formed in the center, and the strain detection circular hole 4 is sandwiched between them, in other words, symmetrical with respect to the longitudinal center axis (hereinafter referred to as “Y axis”) and A pair of parallel long holes 5 and 6 are formed.
Then, strain gauges SG1 to SG4 (however, SG3 and SG4 do not appear in FIG. 7) are attached to the central axis in the short direction (hereinafter referred to as “X axis”) of the inner wall of the strain detecting circular hole 4. is there.
The load transducer 7 of the first conventional example shown in FIG. 6 and FIG. 7 having such a configuration has a circular hole 2 for receiving a load by a mounting pin (not shown) on an object to be measured (not shown). 3 is attached, and when a tensile force acts on the load receiving circular holes 2 and 3 from the object to be measured, the cross-sectional area is reduced due to the presence of the long holes 5 and 6 and the strain detecting circular hole 4. In addition, stress concentration occurs in the cross-sectional portion of the strain detection circular hole 4 on the X axis, and the maximum tensile strain is generated.
[0003]
The strain gauges SG1 and SG3 attached to the portion where the maximum tensile strain is generated with the sensitive axis directed in the Y-axis direction are expanded to increase the resistance value, and the sensitive axis is directed in a direction perpendicular to the Y-axis direction. The strain gauges SG2 and SG4 attached thereto are compressed to reduce the resistance value. Among these strain gauges SG1 to SG4, strain gauges SG1 and SG3 are arranged on opposite sides of the bridge, and strain gauges SG2 and SG4 are arranged on two sides (opposite sides) adjacent to the bridge, thereby providing a Wheatstone bridge circuit (hereinafter, “ In some cases, an electrical signal corresponding to the tensile force is obtained from the output end of the bridge circuit.
The load transducer according to the second conventional example shown in FIGS. 8 and 9 has load receiving circular holes 12 and 13 at both ends of the strain generating body 11 made of a metal elastic body having a substantially rectangular plate shape, respectively. A strain detection countersink hole 14 is drilled in the center to the center in the thickness direction. The strain detection countersink hole 14 is sandwiched between the sides, that is, symmetrically and parallel to the Y axis. The narrowed portion 15 is formed by cutting.
Then, two strain gauges SG1 and SG3 are attached to the portion indicated by the arrow A at the bottom of the strain detection countersink hole 14 with the sensitive axis aligned in the Y-axis direction as shown in an enlarged view in FIG. The other two strain gauges SG2 and SG4 are attached with the sensitive axis aligned in the X-axis direction.
[0004]
The load transducer 16 according to the second conventional example shown in FIGS. 8 and 9 having such a configuration is provided with a load receiving circular hole 12 by a mounting pin (not shown) on a measurement object (not shown). And 13 are attached, and when a tensile force acts on the load receiving circular holes 12 and 13 from the object to be measured, stress is applied to the portion where the cross-sectional area is reduced due to the presence of the constricted portion 15 and the strain detecting countersink hole 14. Concentration and the maximum tensile strain occurs.
A strain gauge SG1 attached to the bottom of the strain detecting countersink 14 (the central portion in the thickness direction of the strain-generating body 11), which is the portion where the maximum tensile strain occurs, with the sensitive axis directed in the Y-axis direction; SG3 is expanded and the strain gauges SG2 and SG4 attached with the sensitive axis directed in the X-axis direction are compressed.
Among these strain gauges SG1 to SG4, the strain gauges SG1 and SG3 are disposed on opposite sides of the bridge circuit, and the strain gauges SG2 and SG4 are disposed on the sides adjacent to the opposite sides to constitute a bridge circuit. An electric signal corresponding to the tensile force is obtained from the output end of the bridge circuit.
[0005]
[Problems to be solved by the invention]
However, both the first and second conventional examples described above have the following problems.
That is, in the first conventional example and the second conventional example, first, four strain gauges SG1 to SG4 are used to form a bridge circuit. From the output end of the bridge circuit, Only a strain output equivalent to 2.6 times the strain value ε (2.6ε) can be obtained, and the sensitivity remains low.
In other words, in the first and second conventional examples described above, the strain gauges SG1 and SG3 generate tensile strains ε1 and ε3, and the strain gauges SG2 and SG4 generate compressive strains ε2 and ε4, but ε2 and ε4 are ε1. And the strain amount of ε3 is 1, only a strain amount corresponding to Poisson's ratio −0.3ε1 (−0.3ε3) is generated.
| Ε2 | = | ε4 | = | 0.3ε1 | = | 0.3ε3 |
The strain amount of the relationship is obtained.
[0006]
Therefore, when these strain gauges SG1 to SG4 are connected as described above to form a bridge circuit,
ε = ε1 + ε2- (ε3-ε4) = 2.6ε1
The output ε is obtained from the output terminal of the bridge circuit.
Therefore, in order to generate the required strain proportional to the load, it is necessary to use high-strength special steel or the like having a large strength, and thus there is a problem that material costs, processing costs and the like increase.
Second, in both the first and second conventional examples, the elongated holes 5 and 6 and the narrowed portion 15 formed by cutting are formed so as to sandwich the strain detecting circular hole 4 and the strain detecting countersink hole 14. There is a problem that the rigidity of the portion that has been made is low and the safety factor has to be small.
[0007]
Third, although the first and second conventional examples are related to the second problem, the cross-sectional area in the vicinity of the strain detection unit is small, so that it is susceptible to interference, for example, bending force or twisting force acts. In this case, there is a problem that bending force or twisting force is mixed in the pulling force and it is difficult to take out the output corresponding to the accurate pulling force.
Fourth, in the case of the first conventional example, the load receiving circular holes 2 and 3 and the strain detecting circular hole 4 may be drilled by a drill or the like, so that the processing is easy and therefore the processing cost is also moderate. However, since the long holes 5 and 6 are accompanied by cutting by an end mill or the like, there is a problem that processing is troublesome and processing time is long, and the processing cost is increased accordingly.
In the case of the second conventional example, since the load receiving circular holes 12 and 13 may be drilled by a drill or the like, they are easy to process, and therefore the processing cost is not so high. The counterbore 14 is accompanied by cutting by an end mill or the like, and the narrowing portion 15 is accompanied by a cutting operation by a milling machine or the like. Therefore, the machining is troublesome and takes time, and thus the machining cost increases. is there.
[0008]
The present invention has been made in view of the above-described circumstances, and a first object is to provide a highly sensitive load converter, and a second object is to provide a load converter that can improve a safety factor. The third purpose is to provide a load transducer that is highly rigid and is less susceptible to interference such as bending and twisting. The fourth purpose is easy to process and low cost. A fifth object of the present invention is to provide a load transducer that can be applied, and a fifth object is that the degree of freedom of attachment of the strain gauge to the strain detector of the strain-causing body is large and the strain gauge attachment work is easy, and the strain An object of the present invention is to provide a load transducer with less detection variation.
[0009]
[Means for Solving the Problems]
  The invention according to claim 1 is the first to the first.5In order to achieve the above objective, a strain gauge is attached to the strain-generating portion of the strain-generating body having a substantially rectangular plate shape, and applied to the load receiving circular holes respectively drilled at both longitudinal ends of the strain-generating body. In the load transducer for detecting a tensile load, a strain detecting circular hole is formed in a central portion of the strain generating main body, and a central axis in the longitudinal direction and a short side perpendicular thereto are formed around the strain detecting circular hole. Four strain adjustment circular holes are drilled symmetrically with respect to the direction center axis,Of the circular holes for strain adjustment, the distance between the inner walls closest to each other in the circular holes for strain adjustment adjacent in the short direction is a, and one of the short side walls of the strain generating body and the other side are the most. The distance between each inner wall of the strain detecting circular hole on the near side is b, and the distance between the inner wall of the strain detecting circular hole and the inner wall of the strain adjusting circular hole closest to the inner wall is c. When
  a ≒ b ≒ 2c
The strain detection circular hole and the strain adjustment circular hole are drilled so as to satisfy the following relationship, and two on the longitudinal axis inside the strain detection circular hole and two on the short axis. Attach strain gauges to a total of four locations,
  The strain gauges are arranged on the opposite sides of the bridge, and the two pieces of the strain gauges that are attached approximately in alignment with the central axis of the longitudinal direction. A Wheatstone bridge circuit is formed by disposing strain gauges on adjacent sides of the bridge,When a tensile load acts on the pair of load receiving circular holes, the strain gauge is configured to detect a high-output electric signal corresponding to the tensile load.
[0010]
  ContractClaim2In order to achieve the first to fifth objects described above, the distance between the inner wall of the load receiving circular hole and the inner wall of the strain adjusting circular hole closest to the inner wall is d and When
  d ≧ 2a≈2b
  The load receiving circular hole and the strain adjusting circular hole are formed so as to satisfy the following relationship.
[0011]
  Claim3In order to achieve the first to fourth objects, the strain gauge is an inner wall of the strain detecting circular hole and is substantially along the central axis in the thickness direction of the strain generating body. The sensory axis is aligned, and the center of the sensory part is substantially aligned and attached to the longitudinal central axis and the lateral direction line..
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
1 to 4 show the configuration of the high-rigidity load converter according to the first embodiment of the present invention. Among these, FIG. 1 is a perspective view showing the external configuration of the high-rigidity load converter, 2 is a front view thereof, FIG. 3 is a cross-sectional view taken along the line YY of FIG. 2, and FIG. 4 is a strain gauge attached to the strain detection unit (strain generation unit) of the strain generation body of FIGS. FIG.
1 to 4, reference numeral 21 denotes a strain generating body made of a metal elastic body, for example, high-strength steel, aluminum, etc., and having a generally rectangular plate shape as a whole, and both ends thereof, that is, a longitudinal central axis Load receiving circular holes 22 and 23 are drilled by drills driven by a drilling machine at both end portions (hereinafter referred to as “Y-axis”) (near the upper end and lower end in FIG. 1). A strain detecting circular hole 24 centering on a point intersecting with the short direction center axis (hereinafter referred to as “X axis”) is formed by the same means.
Around the strain detecting circular hole 24 (strain generating portion), four strain adjusting circular holes 25 to 28 are formed symmetrically with respect to the Y axis and the X axis, respectively.
[0013]
Strain gauges SG1 to SG4 are attached by bonding, sputtering, fusing, or other means on the inner wall surface of the strain detecting circular hole 24 of the strain-generating body 21 thus formed on the Y axis and in the vicinity of the X axis. .
Among the strain gauges SG1 to SG4, the strain gauges SG1 and SG3 substantially align the sensory axis with the center line in the thickness direction of the strain-generating body 21, and the center of the sensory part is on the X axis and for strain detection. Attached to the inner peripheral wall of the circular hole 24 at symmetrical positions separated from each other by 180 °.
The other strain gauges SG2 and SG4 have their sensitive axes substantially aligned with the plane including the central axis in the thickness direction of the strain-generating main body 21, and the center of the sensitive section is on the Y-axis and of the strain-generating main body 21. Affixed to the inner peripheral wall of the strain detection circular hole 24 at a symmetrical position spaced apart from each other by 180 °, approximately in line with the thickness direction center line.
The strain gauges SG1 to SG4 attached to the inner peripheral wall surface of the strain detecting circular hole 24 of the strain generating body 21 formed as described above are connected to a bridge circuit as shown in FIG.
[0014]
That is, the strain gauges SG1 and SG3 attached with the center of the sensitive part aligned with the center axis of the X-axis direction are distributed on the opposite sides of the bridge circuit, and the center of sensitivity is aligned with the center axis of the Y-axis direction. The attached strain gauges SG2 and SG4 are distributed and arranged on the opposite sides of a pair of bridge sides adjacent to the strain gauges SG1 and SG3 of the bridge circuit to form a bridge circuit as shown in FIG. .
As shown in FIG. 4, the positive side of the bridge power source Ein is connected to the connection point A between the strain gauges SG3 and SG4 of the bridge circuit, and the negative side of the bridge power source Ein is connected to the connection point B between the strain gauges SG1 and SG2. To do. Further, the connection point C between the strain gauges SG1 and SG4 is connected to, for example, the positive side of a strain measuring instrument (not shown), and the connection point D between the strain gauges SG2 and SG3 is connected to the negative side.
Next, the operation of the high-rigidity load converter 29 according to the embodiment of the present invention having such a configuration will be described.
First, the high-rigidity load transducer 29 is inserted into a measured object, for example, a load transmission system such as a wire of a crane, and the mounting pins are inserted into the load receiving circular holes 22 and 23, respectively. Connect and fix.
[0015]
As shown in FIG. 1, assuming that loads in opposite directions, that is, tensile forces F and F ′, are applied to the load receiving circular holes 22 and 23 from the object to be measured, the X axis of the inner wall of the strain detecting circular hole 24 The strain gauges SG1 and SG3 attached together with the sensitive center are stretched to generate tensile strains of ε1 and ε3, respectively, and the strain gauges SG2 and SG4 attached together with the sensitive center on the Y axis. Are compressed to produce compression strains of -ε2 and -ε4, respectively.
In the first embodiment of the present invention, four strain adjustment circular holes 25, 26, 27, and 28 are formed around the strain detection circular hole 24 symmetrically with respect to the Y axis and the X axis, respectively. Therefore, strains that are substantially equal in absolute value are generated in the vicinity of the Y axis and the vicinity of the X axis of the strain detection circular hole 24. That is, the following relationship is obtained.
| Ε1 | = | ε2 | = | ε3 | = | ε4 | (1)
The strain gauges SG <b> 1 to SG <b> 4 have their sensory axis directions along a plane including the central axis (neutral axis) in the thickness direction of the strain generating body 21 and at the center in the thickness direction of the strain generating body 21. The strain gauges SG1 and SG3, which are attached together with the center of the sensing part and attached together with the center of the sensing part on the X axis of the inner wall of the strain detection circular hole 24, have tensile strains of ε1 and ε3. Is applied, and compressive strains of -ε2 and -ε4 are applied to the strain gauges SG2 and SG4 attached with the center of the sensitive part aligned on the Y axis.
[0016]
As shown in FIG. 3, the strain gauges SG1 to SG4 acting as described above generate tensile strains ε1 and ε3. The strain gauges SG1 and SG3 are arranged on opposite sides of the bridge circuit, and compressive strains −ε2 and −ε4 are applied. The resulting strain gauges SG2 and SG4 are arranged on opposite sides of the bridge adjacent to the strain gauges SG1 and SG3, respectively, and supply a positive bridge power source to the connection point A of the strain gauges SG3 and SG4. By supplying a negative bridge power supply to the connection point B, the connection point C between the strain gauges SG1 and SG4 and the connection point D between the strain gauges SG2 and SG3,
ε1 + ε3 − (− ε2−ε4) ≈4ε1 (2)
The distortion output voltage Eout corresponding to is obtained.
That is, in the embodiment of the present invention, a four-fold distortion output as a whole can be obtained by assembling the bridge circuit, whereas the conventional load converter shown in FIGS. 6, 7, 8 and 9 is used. In the case of 7 and 16, even if a bridge circuit is built using four strain gauges, the rated output is about 1 under the same strength condition compared to the one that can obtain only 2.6 times the strain output as a whole. .5 times higher (ie 4 / 2.6≈1.5).
[0017]
As described above, according to the embodiment of the present invention, the sensitivity can be improved. Therefore, if the cross-sectional area is the same, the strain output can be greatly increased as compared with the conventional one. Can greatly improve the safety factor. In other words, according to the embodiment of the present invention, in order to obtain a strain generating body having the same rated capacity, it is not necessary to use a high-strength, high-strength special steel, and the metal elastic body is inexpensive and easy to process. Since materials can be used, material costs and processing costs can be reduced, and cost can be reduced accordingly.
Further, according to the above-described embodiment, the strain adjusting circular holes 25, 26, 27, and 28 are symmetrically arranged around the strain detecting circular hole 24 around the X axis and the Y axis in the X axis direction. Is formed in a relational position so as not to overlap with the strain detecting circular hole 24, and therefore, the torsional rigidity and the bending rigidity are larger than those of the conventional one and are not easily influenced by the torsional force and bending force (receiving interference). It is difficult to provide a load transducer that can take out a strain output accurately corresponding to the tensile force.
Moreover, according to the above-mentioned embodiment, all of the load receiving circular holes 22, 23, the strain detecting circular holes 24, and the strain adjusting circular holes 25 to 28 are circular holes that can be drilled by a drill. Therefore, the processing is easy and the processing time is short, and the processing cost can be reduced accordingly.
[0018]
  Next, a second embodiment of the present invention will be described with reference to FIG.
  In FIG. 5, reference numeral “a” denotes a strain adjustment circular hole 25 adjacent to the X axis direction (short direction) among the strain adjustment circular holes 25 to 28.27And the distance (dimension) between the closest inner walls of the strain adjusting circular holes 26 and 28.
  Further, in FIG. 5, reference numeral “b” denotes a strain detecting circle on one side (upper end surface in FIG. 5) and the other (lower end surface in FIG. 5) of the side wall in the X-axis direction and the side closest thereto. The distance (dimension) between each inner wall of the hole 24 is meant.
  In FIG. 5, the symbol “c” indicates the distance between the inner wall of the strain detecting circular hole 24 and the strain adjusting circular holes 26 and 27 (or the strain adjusting circular holes 25 and 28) closest to the inner wall. Means (dimension).
  In FIG. 5, the symbol “d” denotes a distance (dimension) between the load receiving circular holes 22 (and 23) and the inner walls of the strain adjusting circular holes 25 and 27 (and 26 and 28) closest to the inner wall. ).
[0019]
Although a, b, c, and d having such definitions can be set as appropriate, in the embodiment shown in FIG.
a≈b≈2c (3)
The diameter of the strain detecting circular hole 24 and the positions and diameters of the strain adjusting circular holes 25 to 28 are set so as to satisfy the following relationship.
When a, b, c, and d are respectively set in such a relationship, the stress distribution range of the stress concentration in the portion to which the strain gauges SG1 to SG4 are attached becomes wide, and the attachment positions of the strain gauges SG1 to SG4 are shifted. Also exhibits an excellent characteristic that the detected stress hardly changes.
Accordingly, in the conventional work, for example, when attaching the strain gauges SG1 to SG4 on the X-axis and the Y-axis in the vicinity of the center in the thickness direction of the inner wall of the strain detection circular hole 24, attention should be paid. Although it was necessary to concentrate and strictly align and carefully perform the bonding operation, a load transducer formed so as to satisfy the relationship of a≈b≈2c as in the second embodiment described above According to the present invention, since strain gauges SG1 to SG4 may be attached to the approximate positions, attachment work such as adhesion, fusion, and sputtering can be facilitated and performed in a short time, and a load transducer with stable characteristics can be obtained. Obtainable.
[0020]
Further, when designing a link type load transducer of this type having a required rated capacity, the diameter of the strain detection circular hole is set together with factors such as the material, thickness, width and length of the strain generating body 21. The position and diameter of the strain adjusting circular hole, and further, the position and diameter of the load receiving circular hole must be determined. Since there are many design elements as described above, while repeating trial and error, Although a lot of time was spent in determining each element value, according to the second embodiment described above, various elements can be determined in a short time without unnecessary trial and error, and the design cost is reduced. Can be significantly reduced.
Further, as in the second embodiment, the positional relationship between the load receiving circular holes 22 and 23 and the strain adjusting circular holes 25 to 28 closest to the load receiving circular holes 22 and 23 is as follows.
d ≧ 2a≈2b (4)
Thus, the unevenly distributed load transmitted from the load receiving circular holes 22 and 23 is converted into the load receiving circular holes 22 (or 23) and the strain adjusting circular holes 25 and 27 (or 26). , 28), the stress is diffused (distributed) in the portion of the rigid body at the distance d, and the stress distribution is made uniform at the stage of reaching the strain detecting circular hole 24 as the strain generating portion.
[0021]
As a result of the stress being made uniform (smoothed) in this way, the tensile load is correctly transmitted to the inner wall of the strain detection circular hole 24, and the electrical force accurately corresponds to the tensile force applied to the object to be measured such as a wire. The output can be taken out by strain gauges SG1 to SG4.
Conversely, d <2a≈2b
In such a case, there is a possibility that an electrical output accurately corresponding to the tensile load cannot be obtained.
The present invention is not limited to the embodiment described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.
[0022]
【The invention's effect】
  As described in detail above, according to the first aspect of the present invention, a strain gauge is attached to the strain-generating portion of the strain-generating body having a substantially rectangular plate shape, and the strain-straining body is respectively drilled at both longitudinal ends. In the load transducer for detecting a tensile load applied to the load receiving circular hole, a strain detecting circular hole is formed in a central portion of the strain generating body, and a longitudinal direction is formed around the strain detecting circular hole. Four circular holes for strain adjustment are drilled symmetrically with respect to the central axis and the lateral central axis perpendicular to the central axis,Of the circular holes for strain adjustment, the distance between the inner walls closest to each other in the circular holes for strain adjustment adjacent in the short direction is a, and one of the short side walls of the strain generating body and the other side are the most. The distance between each inner wall of the strain detecting circular hole on the near side is b, and the distance between the inner wall of the strain detecting circular hole and the inner wall of the strain adjusting circular hole closest to the inner wall is c. When
a ≒ b ≒ 2c
The strain detection circular hole and the strain adjustment circular hole are drilled so as to satisfy the following relationship, and two on the longitudinal axis inside the strain detection circular hole and two on the short axis. Attach strain gauges to a total of four locations,
  The strain gauges are arranged on the opposite sides of the bridge, and the two pieces of the strain gauges that are attached approximately in alignment with the central axis of the longitudinal direction. A Wheatstone bridge circuit is formed by disposing strain gauges on adjacent sides of the bridge,Since a high output electrical signal corresponding to the tensile load can be detected by the strain gauge when a tensile load acts on the pair of load receiving circular holes, the sensitivity can be improved and the same The rated output can be increased about 1.5 times under the above conditions, and the rigidity can be greatly increased, and the safety factor can be greatly improved. It is possible to use a metal elastic body material that is inexpensive and easy to process without using special steel, and can save material costs and processing costs.In particular,The torsional rigidity is larger than the conventional ones, and even if bending force or torsional force is applied to the load transducer together with the tensile load, it is difficult to receive the influence, that is, interference, so the strain output (electrical output) that accurately corresponds only to the tensile force ) Can be provided.
[0023]
  Claims1According to the invention described in, HiThe stress distribution range of the stress concentration at the part where the strain gauge is attached is widened. Therefore, even if the attachment position of each strain gauge deviates from the intended position, the detected stress hardly changes and it corresponds to a stable tensile stress. Electrical output can be obtained, and therefore it is only necessary to attach strain gauges at roughly the positions, so that attachment work such as adhesion and fusion can be performed easily and in a short time. In addition, since the relationship between the strain detection circular hole and the strain adjustment circular hole may be defined so as to satisfy a≈b≈2c, various elements can be obtained in a short time without unnecessary trial and error. Can thus be determined and thus the design cost can be significantly reduced.
  Furthermore, according to the invention described in claim 1, the strain gauge is provided with strain gauges attached substantially in alignment with the central axis in the longitudinal direction on the opposite sides of the bridge, respectively. Since the Wheatstone bridge circuit is formed by disposing strain gauges attached almost in line with the center line on the adjacent sides of the bridge, it corresponds to a resistance value change of 4 times the resistance value change of one strain gauge. Therefore, it is possible to extract a load output from the output end of the bridge circuit, and to provide a load converter with extremely high resolution.
[0024]
  Claims2When the distance between the inner wall of the load-receiving circular hole and the inner wall of the strain-adjusting circular hole closest to the inner wall is d in the invention described in (2),
  d ≧ 2a≈2b
  Since the load receiving circular hole and the strain adjusting circular hole are formed so as to satisfy the relationship, the uneven distribution transmitted from the load receiving circular hole is At the stage where the stress is diffused in the rigid part at the distance d between the circular hole for use and the strain detecting circular hole that is the strain generating part, the stress distribution is made uniform, and the stress distribution is correctly applied to the inner wall of the circular hole for detecting strain It is possible to provide a high-rigidity load transducer in which a tensile load is transmitted and an electrical output that accurately corresponds to the tensile force can be taken out by a strain gauge.
[0025]
  Claims3According to the present invention, the strain gauge is an inner wall of the strain detecting circular hole and is aligned with the sensitive axis so as to be substantially along the central axis in the thickness direction of the strain generating body, and the center in the longitudinal direction. Since the center of the sensitive part is attached to the axial line and the short direction line, the center of the sensitive part of the strain gauge is attached to the bending neutral axis or the twisted neutral axis. Even if torsion is applied to the load transducer, it is canceled by the bridge circuit and is not easily affected. Therefore, even if bending force or torsional force is applied from the object to be measured, it is difficult to be affected. Be.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external configuration of a high-rigidity load transducer according to a first embodiment of the present invention.
FIG. 2 is a front view showing the configuration of the high-rigidity load converter shown in FIG.
3 is a cross-sectional view in the YY line direction of FIG. 2;
4 is a bridge circuit formed by four strain gauges attached to a strain detection circular hole of the high-rigidity load transducer shown in FIGS. 1 and 2. FIG.
FIG. 5 is a front view showing an external configuration of a high-rigidity load transducer according to a second embodiment of the present invention.
FIG. 6 is a front view showing a configuration of a load transducer according to a first conventional example.
7 is a cross-sectional view taken along line YY in FIG.
FIG. 8 is a front view showing a configuration of a load transducer according to a second conventional example.
9 is an enlarged partial front view showing an enlarged state of attachment of four strain gauges attached to a strain detection countersink hole of the load converter shown in FIG. 8. FIG.
[Explanation of symbols]
21 Strain body
22, 23 Load receiving circular hole
24 Circular hole for strain detection
25, 26, 27, 28 Circular holes for strain adjustment
29 High rigidity load transducer
SG1, SG2, SG3, SG4 Strain gauge

Claims (3)

A load for detecting a tensile load applied to a load receiving circular hole formed in each of the longitudinal ends of the strain generating body by attaching a strain gauge to the strain generating section of the strain generating body having a substantially rectangular plate shape. In the converter, a strain detection circular hole is formed in a central portion of the strain generating body, and the strain detection circular hole is symmetric with respect to the longitudinal center axis and the short direction center axis perpendicular thereto. Four strain adjustment circular holes are drilled, and among the strain adjustment circular holes, the distance between the inner walls closest to the strain adjustment circular holes adjacent in the short direction is a, and the strain generating body The distance between one and the other side wall of the short direction side wall and each inner wall of the strain detecting circular hole closest to them is b, and the inner wall of the strain detecting circular hole and the strain nearest to the inner wall are b. Distance between inner wall of adjustment circular hole when the c,
a ≒ b ≒ 2c
The strain detection circular hole and the strain adjustment circular hole are drilled so as to satisfy the following relationship, and two on the longitudinal axis inside the strain detection circular hole and two on the short axis. Attach strain gauges to a total of four locations,
The strain gauges are arranged on the opposite sides of the bridge, and the two pieces of the strain gauges that are attached approximately in alignment with the central axis of the longitudinal direction. One Wheatstone bridge circuit is formed by disposing a strain gauge on each adjacent side of the bridge, and when the tensile load acts on the pair of load receiving circular holes, the strain gauge corresponds to the tensile load. A high-rigidity load transducer configured to detect a high-output electric signal. When the distance between the inner wall of the load receiving circular hole and the inner wall of the strain adjusting circular hole closest to the inner wall is d,
d ≧ 2a≈2b
The relationship to satisfy the high rigidity load converter according to claim 1, characterized in that bored and adjusting the circular hole strain the circular hole for receiving the load. The strain gauge is an inner wall of the strain detection circular hole, and is aligned with the sensitive axis so as to be substantially along the central axis in the thickness direction of the strain generating body, and on the longitudinal central axis and the short direction line. The high-rigidity load strain detector according to claim 1 or 2 , wherein the center of the sensing part is attached so as to be substantially aligned.

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