JP2004045205A - Force gauge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a force meter with a simple constitution which is superior in overload prevention and capable of accurate measurement. <P>SOLUTION: The force meter is arranged in between a loading receiver 12 and a base 14, and provided with a load detection means detecting an axial direction load working between the loading bridge 12 and the base 14. The load detection means is constituted of a strain element 22A formed by providing a penetration hole 24 on the side opposite to a metal block of nearly square shape and a load cell provided with a strain gauge 28 arranged in a thin strain generating part 26 of the strain element 22A. Values detected with the strain gauge 28 is indicated in digits on an indicator 30. On a load working axis line L, an overload prevention mechanism (slit 24c) is provided, which is superior in overload prevention and capable of high accuracy detection of load with the strain gauge 28 arranged in a strain generating part 26 of the strain element 22A with easy design. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dynamometer used for calibration of a one-axis testing machine for detecting an applied load from deformation of an annular spring to which a load is applied, and more particularly to an overload prevention mechanism for protecting an annular spring or the like from an excessive load. The present invention relates to a dynamometer provided with:
[0002]
[Prior art]
As shown in FIGS. 9A and 9B, a conventional dynamometer is used by being interposed between a load receiver 1 and a base 8 of a load tester. By measuring the amount of deflection of the spring 2 with the dial gauge 4, the force applied to the annular spring 2, that is, the load, is measured.
[0003]
Reference numeral 3 denotes an overload (overload) prevention mechanism including a pair of projections 3a and 3b provided inside the annular spring 2 so as to face each other. , 3b contact and carry an excessive load, so that the annular spring 2 is not deformed more than necessary, and damage to the annular spring 2 and the dial gauge 4 is prevented.
[0004]
[Problems to be solved by the invention]
In order to accurately measure the amount of deflection of the annular spring 2 in this type of dynamometer, the dial gauge 4 is arranged at the center of the annular spring 2 which is not affected by the eccentricity or runout of the applied force. Is desirable.
[0005]
In order for the overload prevention mechanism 3 to function most effectively, it is desirable to provide the overload prevention mechanism 3 at the center of the annular spring 2 on the line of action of the load.
[0006]
However, since it is difficult to dispose both the dial gauge 4 and the overload prevention mechanism 3 at the center of the annular spring 2, the first prior art disposes the overload prevention mechanism 3 at the center of the annular spring 2. At the same time, the dial gauge 4 is arranged at a position offset to the front side of the center of the annular spring 2. Reference numerals 5a and 5b denote operating pieces provided above and below the annular spring 2, respectively, and the dial gauge 4 is disposed between the operating pieces 5a and 5b.
[0007]
Further, the second prior art has a structure in which the dial gauge 4 is arranged at the center of the annular spring 2 and the overload prevention mechanisms 3 (3a, 3b) are arranged at symmetrical positions of the center of the annular spring 2. Has become.
[0008]
For this reason, in the first prior art, since the amount of deflection at a position offset from the center of the annular spring is detected, accurate measurement cannot be performed. In the second conventional technique, two sets of overload prevention mechanisms 3 are required, and the size of the annular spring 2 is increased, so that the device becomes complicated and large. Further, there is a problem that the measurement accuracy using a dial gauge is up to ± 0.2%, and it is difficult to measure with higher accuracy.
[0009]
Then, the inventor considered whether a load cell widely used as a load detecting means of an electronic weighing scale or an electronic weigher could be used for this force meter. That is, the load cell attaches a strain gauge to a thin-walled strain-generating portion of the strain-generating body, detects a strain generated in the strain-generating portion when a load is applied to the strain-generating body, and detects the strain with the strain gauge. By obtaining the load, highly accurate measurement is possible.
[0010]
Further, for example, if the annular spring itself is formed of a strain-generating body, the degree of freedom of where the strain-generating portion is formed is high, and it is easy to provide an overload (overload) prevention mechanism on the line of action of load. High accuracy detection is possible with a strain gauge instead of a dial gauge.
[0011]
Then, the inventor actually manufactured a prototype of a dynamometer using the load cell as an annular spring and confirmed its accuracy and overload prevention function.It was confirmed that the dynamometer was very excellent, so the inventors came to propose the present invention. It is a thing.
[0012]
The present invention has been made on the basis of the problems of the related art and the findings of the inventor, and a first object of the present invention is to provide a dynamometer having a simple structure capable of performing highly accurate measurement. A second object of the present invention is to provide a dynamometer having a simple structure which is excellent in overload prevention and can perform high-precision measurement.
[0013]
[Means for Solving the Problems]
In order to achieve the first object, in the dynamometer according to claim 1, a load detector is disposed between a load receiver and a base and detects an axial load acting between the load receiver and the base. A dynamometer with means,
The load detecting means is a load cell formed of a strain-generating body formed by providing a through-hole on a facing side of a substantially rectangular metal block, and a strain gauge disposed in a thin strain-generating portion of the strain-generating body. Make up,
The value detected by the strain gauge was digitally displayed on a display.
[0014]
In order to achieve the second object, in the dynamometer according to the first aspect, in the dynamometer according to the first aspect, the through-hole is formed in an eyeglass shape and the strain body is formed symmetrically. A gauge is also arranged symmetrically, and the load cell is configured symmetrically with respect to a load acting axis connecting the load receiver and the base,
An overload prevention mechanism constituted by a slit communicating between a pair of left and right substantially circular holes constituting the eyeglass-type through-hole is provided at a central portion in the left-right direction of the strain body.
[0015]
According to a third aspect of the present invention, in the dynamometer according to the first aspect, both ends of the strain body having the through-holes formed in a symmetrical manner in a pair of glasses are supported via a spacer member, and the load receiver and the base are connected to each other. Along with configuring the strain body symmetrically with respect to the load acting axis to be tied,
An annular spring is interposed between the spacer member and the base, and protrudes from the base side into a central portion of the coronal spring through a central through-hole of the coronal spring, and approaches the bottom surface of the strain body. An overload prevention mechanism including a stopper member is provided.
[0016]
According to a fourth aspect of the present invention, in the dynamometer according to the first aspect, the through-hole is formed in a spectacle shape in a bilaterally symmetrical manner, and the strain generating body is cantilevered via a spacer member.
An annular spring is interposed between the spacer member and the base, and the load-applying end of the strain-generating body corresponds to the center of the annular spring on the load-applying axis connecting the load receiver and the base, and the strain-generating body is provided. Arranged so that the fixed end of the ring spring is offset left and right from the center of the annular spring,
An overload prevention mechanism is provided at a central portion of the coronal spring, which is configured by a stopper member that protrudes from the base side and penetrates through a central portion through-hole of the coronal spring to approach the bottom surface of the strain body. .
[0017]
Further, in the dynamometer according to claim 5, the dynamometer is provided between the load receiver and the base, comprising a load detecting means for detecting an axial load acting between the load receiver and the base,
The load detecting means, a diaphragm-type flexure element, and a load cell composed of a strain gauge disposed in a thin flexure portion of the flexure element,
Digitally display the value detected by the strain gauge on a display,
Supporting the periphery of the diaphragm-type strain body with a spacer member, and interposing an annular spring between the spacer member and the base,
A stopper that protrudes from the base side and penetrates into a central portion of the crown spring, which is on a load acting axis line connecting the load receiver and the base, penetrates the central portion of the crown spring, and is close to the bottom surface of the strain body. An overload prevention mechanism composed of members is provided.
[0018]
(Function) In the first aspect, the load detecting means is constituted by a load cell in which a strain gauge is arranged at the strain-generating portion of the strain-generating body. In the second aspect, the conventional annular spring itself is constituted by a beam-shaped strain-generating body. In claim 3, both ends of the beam-shaped flexure element are supported by annular springs. In claim 4, the fixed end side of the beam-shaped flexure element is cantilevered by an annular spring. A load cell widely used as a load detecting means of an electronic weighing scale or an electronic scale (e.g., a strain-generating portion of a strain-generating body), in which a peripheral portion of a disk-shaped diaphragm-type strain generating body constituting a load cell is supported by an annular spring. The force gauge is configured using a strain gauge disposed on the strain gauge. Therefore, when a load acts on the force gauge between the load receiver and the base, a strain is generated in the thin-walled strain-generating portion of the strain-generating body. This strain is detected by the strain gauge placed in the strain section, and the It is digitally displayed as a load value on the display unit.
[0019]
In the load cell (a load detecting means in which a strain gauge is arranged at the strain-generating portion of the strain-generating body), the degree of freedom in forming a thin-walled strain-generating portion in the strain-generating body is high. It is easy to provide an overload prevention mechanism on the load application axis in the above, and to provide a thin strain generating section at a predetermined position avoiding on the load application axis in the strain generating element and arrange the strain gauge. The configuration is also simple. In addition, even if the strain-generating part and strain gauge are provided at a position distant from the load acting axis on the strain-generating body, the load measurement accuracy is no different from the case where the strain-generating part and strain gauge are arranged on the load acting axis. is not.
[0020]
In addition, an overload prevention mechanism is provided on the load application axis of the flexure element, so an unexpected bending moment does not act on the flexure element during overload action, and the thin flexure element is easily deformed. It is possible to reliably prevent the overload from acting on the portion.
[0021]
According to a sixth aspect of the present invention, in the dynamometer according to any one of the first to fifth aspects, a steel ball serving as a load transmitting unit is interposed between the load receiver and the strain generating element. .
[0022]
(Action) The lateral load acting on the strain body from the load receiver is reduced by rolling the steel ball, and only the axial force acts on the force gauge.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail based on examples.
[0024]
1 and 2 show a first embodiment of the present invention. FIG. 1 is a front view showing the entire configuration of a dynamometer according to the first embodiment. FIG. 2 is a longitudinal sectional view of the dynamometer (FIG. 1). FIG. 2 is a sectional view taken along line II-II shown in FIG.
[0025]
In these figures, reference numeral 20A denotes a dynamometer interposed between the upper cylindrical load receiver 12 and the lower disk-shaped base 14 of the uniaxial testing machine, and is used as a dynamometer 20A. Indicates a strain generating body 22A constituting an annular spring, a strain gauge 28 attached to a thin strain generating portion 26 of the strain generating body 22A, and a display that converts the strain detected by the strain gauge 28 into a load and digitally displays the load. It is mainly composed of a vessel 30 (see FIG. 2).
[0026]
The flexure element 22A is provided with a pair of spectacle-shaped through-holes 24 on opposing side surfaces of a substantially rectangular metal (for example, aluminum or iron alloy) block whose four corners are chamfered at 45 degrees, and is symmetrical left and right (in the horizontal direction in FIG. 1). The pair of left and right substantially circular holes 24a and 24b forming the eyeglass-type through-hole 24 form thin-walled symmetrically at two locations on the upper and lower sides of the strain body 22A. A distortion portion 26 is formed. A concave portion 27 is formed on the lower surface of the pair of lower left and right strain generating portions 26, 26, and strain gauges 28, 28 are affixed in the concave portion 27 so as to be symmetric in the left-right direction.
[0027]
Further, the center in the left-right direction of the strain body 22A constituting the dynamometer 20A is connected to an upper iron alloy load receiver 12 and a lower iron alloy base 14, respectively. The left and right strain generating portions 26, 26 of the strain generating body 22A are configured symmetrically with respect to a load acting axis L passing through the respective centers of the base 12 and the base 14 by a compressive load acting between the load receiver 12 and the base 14. Almost the same stress acts on each. That is, a load cell is constituted by the strain generating body 22A and the strain cage 23, and the strain generated in the strain generating portions 26, 26 is detected by the strain gauges 28, 28, and a digital display having an arithmetic processing function is provided through an output code 29. Output to the container 30. In the digital display 30, a load value corresponding to the distortion is calculated, and the load value is digitally displayed on the liquid crystal display unit 31. In the measurement using the strain gauge 28, a highly accurate measurement with a measurement accuracy of ± 0.03% is possible.
[0028]
A narrow slit 24c communicating between the pair of left and right substantially circular holes 24a and 24b constituting the eyeglass-type through hole 24 is provided between the pair of left and right substantially circular holes 24a and 24b. Is provided with an overload prevention mechanism 25. That is, the overload prevention mechanism 25 is constituted by the upper region 25a between the holes 24a and 24b and the lower region 25b between the holes 24a and 24b in the strain body 22A opposed in the vertical direction across the slit 24c. The excessive compressive load acting on the flexure element 22A via the load receiver 12 is carried by the overload prevention mechanism 25, and the excessive flexure caused by the excessive load acts on the flexure portion 26 of the flexure element 22A and breaks. Such troubles do not occur.
[0029]
Further, ball bearing surfaces 12a and 22a (see FIG. 2) are provided on the bottom surface of the load receiver 12 and the upper surface of the strain body 22A, respectively, and a steel ball 16 serving as a load transmitting means is interposed between the two 12a and 22a. Since the lateral force from the load receiver 12 acting on the flexure element 22A is reduced by the rolling of the steel ball 16, only the axial load is applied to the dynamometer 20A (the flexure element 22A). Works. Reference numerals 13 and 13 are bolts for connecting the load receiver 12 and the strain body 22A to hold the steel ball 16. Reference numeral 15 denotes a bolt connecting the strain body 22A and the base 14.
[0030]
3 and 4 show a second embodiment of the present invention. FIG. 3 is a sectional view showing the entire configuration of a dynamometer according to the second embodiment, and FIG. 4 is a right side view of the dynamometer.
[0031]
In the dynamometer 2OB of the second embodiment, a strain-generating body 22B having a both-ends support structure is disposed on a ring-shaped spring member 40 formed in a horizontally long and substantially rectangular shape with a disk-shaped spacer member 41 interposed therebetween. Both ends of the strain body 22B are fixed to the lower surface of the thick top plate 43 of the rectangular rigid body 42, and are supported in a form suspended in the case 42. Reference numeral 23 denotes a fastening bolt for fixing the strain body 22B to the case 42. The flexure case 42 and the spacer member 41 are fastened by bolts (not shown).
[0032]
The strain body 22B is provided with a pair of left and right through holes 24c and 24d on opposing side surfaces of a substantially rectangular metal (for example, aluminum or iron alloy) block, and thin portions 27 for absorbing moment are provided at both ends. It is formed so as to be symmetrical in the left-right direction (the left-right direction in FIG. 3), and through-holes 24c and 24d form thin-walled strain-generating portions symmetrically in the left-right direction at two locations on the upper and lower sides of the strain-generating body 22B. 26 are formed. The strain gauges 28 and 28 are attached to the lower surface of the lower strain-generating portion 26 so as to be symmetrical in the left-right direction, thereby forming a load cell.
[0033]
A bolt-shaped load receiver 46 is screwed into the center of the strain-generating body 22B in the left-right direction and protrudes upward. A load acts on the strain-generating body 22B via the bolt-shaped load receiver 46, and the above-mentioned first load is applied. As in the embodiment, the strain detected by the strain gauge 28 is digitally displayed on the display 30 (not shown) as a load.
[0034]
The spacer member 41 and the base 14 are connected to the center portion of the annular spring 40 in the left-right direction by bolts 44 and 45. The annular spring 40 is made of duralumin that can maintain strength for a long time, and is used as a force gauge. It is formed horizontally long so that the vertical height can be reduced. Further, through-holes 40a, 40b, 41a, 42a coaxial with the load application axis L are provided in the center in the left-right direction of the annular spring 40, the center of the spacer member 41, and the center in the left-right direction of the strain body 42. A rod-shaped stopper pin 48, which is screwed to the base 14 and suspended, penetrates into the through holes 40a, 40b, 41a and extends to a position close to the bottom surface of the upper strain body 22B. And an overload prevention mechanism.
[0035]
That is, when an excessive compressive load is applied to the flexure element 22B via the bolt 46, the annular spring 40 is compressed in the axial direction via the rigid case 42, so that the flexure element 22B sinks while maintaining the parallelism. Then, the bottom surface of the strain body 22B comes into contact with the stopper pin 48, and the excessive compressive load is carried by the stopper pin 48, and the strain-causing portion 26 of the strain body 22B is subjected to an excessive stress due to the excessive load and breaks. The problem is not caused.
[0036]
In particular, when the flexure element 22B is made of a relatively soft metal such as aluminum, when the stopper pin 48 and the bolt-shaped load receiver 46 are made of a hard metal such as an iron alloy, an excessive load is applied. Since the lower end of the bolt-shaped load receiver abuts against the stopper pin, breakage of the flexure element 22B can be further prevented.
[0037]
FIG. 5 is a sectional view showing the entire configuration of a dynamometer according to a third embodiment of the present invention.
[0038]
In the dynamometer 20B of the second embodiment, the strain body 22B on which a load acts is disposed in a form suspended and supported on the annular spring 40. However, the dynamometer of the third embodiment is used. In 20C, the flexure element 22B is supported at both ends via a spacer member 41A provided with flexure element holding portions 41a1 at both left and right ends.
[0039]
Otherwise, the second embodiment is almost the same as the second embodiment, and the same reference numerals are used to omit redundant description.
[0040]
6 and 7 show the fourth and fifth embodiments of the present invention. FIG. 6 is a cross-sectional view showing the entire configuration of a fourth embodiment of a dynamometer. FIG. 7 is a fifth embodiment of a dynamometer. FIG. 2 is a cross-sectional view showing the overall configuration of the embodiment.
[0041]
In the dynamometers 20B and 20C of the second and third embodiments described above, the flexure elements 22B and 22C to which a load acts are supported at both ends on the annular spring 40. In the dynamometers 20D and 20E of this embodiment, the strain bodies 22D and 22E on which a load acts are cantilevered on the annular spring 40.
[0042]
That is, in the fourth embodiment shown in FIG. 6, a position offset from the center of the annular spring 40 in the left-right direction (right direction in FIG. 6) on the lower surface of the top plate 43 of the rigid case 42 fixed on the spacer member 41. The base end of the strain body 22D is fixed to the center of the annular spring 40 that is aligned with the load application axis L, and the load application end of the horizontally extending strain body 22D is disposed above the center. I have.
[0043]
On the other hand, in the fifth embodiment shown in FIG. 7, the base end of the strain body 22E is fixed to the strain body holding portion 41b at the end of the spacer member 41A fixed to the annular spring 40, and extends horizontally. The load applying end of the protruding strain generating body 22E is disposed above the center of the annular spring 40 that coincides with the load applying axis L.
[0044]
Also, in the flexure elements 22D and 22E in the fourth and fifth embodiments, the eyeglass-shaped through-holes 24A are provided on the side surfaces of the metal blocks to form the thin flexure portions 26. This is a structure in which a strain gauge 28 is attached to the lower surface.
[0045]
The other points are the same as those of the third and fourth embodiments, and the same reference numerals are used to omit the description.
[0046]
FIG. 8 is a sectional view showing the overall configuration of a dynamometer according to a sixth embodiment of the present invention.
[0047]
In the dynamometer 20F according to the sixth embodiment, the strain body 22F connected to the annular spring 40 via the spacer member 41B is formed of a diaphragm-type strain body. That is, the strain body 22F has a structure in which the thick cylindrical portion 23a supported by the disk-shaped spacer member 41B and the thin strain portion 23b corresponding to the top plate of the cylindrical portion 23a are integrally formed. A strain gauge 28 is attached to two equally-spaced portions in the circumferential direction of the disk-shaped strain generating portion 23b. A bolt-shaped load receiver 46 is screwed to the thick portion 23c at the center of the strain generating portion 23, and is provided coaxially with the stopper pin 48.
[0048]
Other configurations are the same as those of the above-described embodiment, and the same reference numerals are given, and the duplicated description will be omitted.
[0049]
【The invention's effect】
As is apparent from the above description, according to the first aspect, a simple dynamometer having a configuration capable of measuring a load with high accuracy is provided.
[0050]
According to the second, third, fourth, and fifth aspects, there is provided a simple dynamometer having a configuration excellent in overload prevention and capable of performing highly accurate measurement.
[0051]
According to the sixth aspect, since only the axial force acts on the dynamometer, more accurate load measurement can be performed.
[Brief description of the drawings]
FIG. 1 is a front view showing the entire configuration of a force meter according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view (sectional view taken along line II-II shown in FIG. 1) of the force meter.
FIG. 3 is a cross-sectional view illustrating an entire configuration of a dynamometer according to a second embodiment of the present invention.
FIG. 4 is a right side view of the force meter.
FIG. 5 is a cross-sectional view illustrating an entire configuration of a dynamometer according to a third embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating an entire configuration of a dynamometer according to a fourth embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating an entire configuration of a dynamometer according to a fifth embodiment of the present invention.
FIG. 8 is a cross-sectional view illustrating an entire configuration of a dynamometer according to a sixth embodiment of the present invention.
FIG. 9A is a perspective view of a first conventional force meter.
(B) It is a perspective view of the force meter which is the 2nd prior art.
[Explanation of symbols]
20A, 20B, 20C, 20D, 20E, 20F Dynamometers 22A, 22B, 22C, 22D, 22E, 22F Strain-generating body 23b, 26 Thin-walled strain-generating portion 40 Ring spring 41, 41A Spacer member 24 Eyeglass-shaped through-hole 24c Slit 28 constituting overload prevention mechanism Strain gauge 48 Stopper pin constituting overload prevention mechanism

Claims (6)

A dynamometer provided between the load receiver and the base, the load meter including load detecting means for detecting an axial load acting between the load receiver and the base,
The load detecting means is a load cell composed of a strain-generating body formed by providing a through hole on a side surface of a substantially rectangular metal block and a strain gauge arranged in a thin-walled strain-generating portion of the strain-generating body. As well as
A force meter wherein a value detected by the strain gauge is digitally displayed on a display. The through-holes are spectacle-shaped, the strain body is formed symmetrically, and the strain gauges are also arranged symmetrically, and the load cell is configured symmetrically with respect to a load acting axis connecting the load receiver and the base. With
2. An overload prevention mechanism comprising a slit communicating between a pair of left and right substantially circular holes constituting the eyeglass-type through-hole is provided at a central portion in the left-right direction of the strain body. The dynamometer described in. The through-hole has a pair of eyeglass-shaped, symmetrically formed strain-generating bodies supported at both ends via a spacer member, and the strain-generating body is formed symmetrically with respect to a load acting axis connecting the load receiver and the base. With
An annular spring is interposed between the spacer member and the base, and a central portion of the crown spring projects from the base side and penetrates through a central through hole of the crown spring to loosen the bottom surface of the strain body. 2. The force meter according to claim 1, further comprising an overload prevention mechanism configured by a stopper member close to the force sensor. The through-hole has a structure in which the strain-generating body formed symmetrically in the shape of a pair of glasses is cantilevered via a spacer member, and an annular spring is interposed between the spacer member and the base. Corresponds to the central portion of the annular spring on the load applying axis connecting the load receiver and the base, and the fixed end of the strain generating element is arranged so as to be offset left and right from the central portion of the annular spring. ,
At the center of the crown-shaped spring, an overload prevention mechanism was provided, which was constituted by a stopper member protruding from the base side and penetrating through a central through-hole of the crown-shaped spring and approaching the bottom surface of the strain body. The dynamometer according to claim 1, wherein: A dynamometer that is disposed between a load receiver and a base and that includes a load detecting unit that detects an axial load acting between the load receiver and the base,
The load detecting means is constituted by a diaphragm-type flexure element, and a load cell composed of a strain gauge arranged in a thin flexure portion of the flexure element,
The value detected by the strain gauge is digitally displayed on a display,
A peripheral edge of the diaphragm-type strain body is supported by a spacer member, and an annular spring is interposed between the spacer member and the base.
A central portion of the crown spring, which is on a load acting axis connecting the load receiver and the base, protrudes from the base side and penetrates through a central through hole of the crown spring to approach the bottom surface of the strain body. A force meter provided with an overload prevention mechanism constituted by a stopper member. The force gauge according to any one of claims 1 to 5, wherein a steel ball serving as a load transmitting means is interposed between the load receiver and the strain body.

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