JPH09236479A - Structure of weight sensor using strain gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve weight detection accuracy of an article to be measured by bringing each strain gauge into uniform contact with an internal peripheral surface of a hole into which a ring is inserted. SOLUTION: A plurality of strain gauges 2 are stuck to a frust-conicak ring 1 comprising rubber as a resiliently deformable material for measuring the weight of an article to be measured through strain. A compression apparatus 3 for applying a compression load to the ring 1 includes an end plate part 3a in contact with one end of the ring 1, and a rod-shaped shaft part 3b coupled substantially perpendicularly to the end plate part 3a and penetrating the ring 1. After a bonding agent is applied on the strain gauge 2, the ring 1 is inserted into a hole 10a formed in a frame or a leg part 10 of a tank, and a screw 6 is clamped whereby a compression load is applied on the ring 1 through the end plate part 3a, and hence the strain gauge 2 is pressed against an inner peripheral surface of the hole 10a. Further, a cap 4 is mounted on the end plate part 3a whereby the weight sensor is protected and is prevented from falling off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a weight sensor using a strain gauge, and more particularly to an improved technique of a load transducer.

[0002]

2. Description of the Related Art Conventionally, since the remaining amount of contents of various storage silos, hoppers, tanks, etc. (hereinafter referred to as "tanks, etc.") cannot be directly confirmed from outside, the remaining amount of contents of tanks, etc. is measured. Various methods have been devised. For example, the remaining amount is measured by a mechanical or electrostatic leveler installed inside the tank, etc., the weighted wire is dropped from the top of the tank, etc., and the remaining amount is measured from the length of the wire, or The ring to which the strain gauge is attached is inserted into a hole formed in a leg portion of a tank or the like, and the remaining amount (weight) of the content is measured from the detected strain.

[0003]

However, in the method of measuring the remaining amount of contents such as a tank from a leveler or a wire, for example, when the contents are powder, the central portion is reduced as the contents decrease. It is difficult to accurately measure the remaining amount of the contents due to the decrease in the concave arching. Therefore, at present, a person climbs a tank or the like using a ladder or the like, hits the outer wall of the tank with a hammer or the like to make the contents substantially horizontal, and then measures the remaining amount.

On the other hand, in the method of measuring the remaining amount using a ring to which a strain gauge is attached, it is difficult to control the dimensional accuracy of the hole into which the ring is inserted, and each strain gauge is evenly distributed on the inner peripheral surface of the hole. There is a problem that the bias of the contact state occurs without contact, so that the accuracy of strain detection is low, and that the temperature of each strain gauge becomes non-uniform due to the bias of the contact state, thereby making it difficult to perform temperature correction easily. Was.

In view of the above-mentioned problems, the present invention solves the above-mentioned problems by making the strain gauge attached to the ring evenly contact the inner peripheral surface of the hole into which the ring is inserted. It is an object of the present invention to provide a weight sensor that has been manufactured.

[0006]

SUMMARY OF THE INVENTION Accordingly, the invention as defined in claim 1 comprises a substantially cylindrical ring, and a plurality of strain gauges attached to the outer peripheral surface of the ring. In a weight sensor that inserts the ring into a hole formed at a location where the weight of the object acts and measures the weight of the object to be measured based on the strain detected by the strain gauge, a material capable of elastically deforming the ring And a deforming device that radially deforms the ring so that the strain gauge is pressed against the inner peripheral surface of the hole by applying a compressive load from the axial direction of the ring.

According to a second aspect of the present invention, the ring is formed so that the outer peripheral surface thereof is tapered so that the leading end side when the ring is inserted into the hole is smaller in diameter than the rear end side. According to a third aspect of the present invention, in the deforming device, an end plate portion abutting on one end portion of the ring, and a rod-shaped shaft portion connected to the end plate portion at a substantially right angle and penetrating in the axial direction of the ring. ,
In the end portion of the shaft portion opposite to the end plate portion,
A screw locked to a locking portion provided separately from the deformation device is screwed in, and a compression load is applied by tightening the screw.

In the invention according to claim 4, a cap for covering the end plate portion and the ring protruding from the hole is attached to the end plate portion.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the structure of a weight sensor using a strain gauge according to the present invention.
Frusto-conical (tapered) ring 1 made of hard and oil-resistant rubber as an elastically deformable material
A strain gauge 2 for measuring the weight of an object to be measured through a strain is attached to an outer peripheral surface of each of the vertical cross section and the horizontal cross section by a double-sided tape or the like. Further, a through hole 1a through which a shaft portion 3b of the compression device 3 described later penetrates is formed in the center of the shaft of the ring 1.

The compressing device 3 for applying a compressive load in the axial direction of the ring 1 is made of a metal having excellent corrosion resistance and rust resistance such as aluminum or stainless steel from the viewpoint of corrosion and rust prevention. Circular end plate part 3 in contact
a and a rod-shaped shaft portion 3 which is joined to the end plate portion 3a at a substantially right angle.
b. The total length of the shaft 3a is set to be shorter than the total length of the ring 1 and the cover 8 described later. Screw holes 3c and 3d are formed at both ends of the compression device 3, that is, at respective ends of the end plate 3a and the shaft 3b. A screw 6 for applying a compressive load in the axial direction of the ring 1 is attached.

On the other hand, a receiving plate 7 against which the other end of the ring 1 contacts.
Has a through hole 7 through which the shaft portion 3b of the compression device 3 passes.
a, and a through hole (not shown) through which the lead wire of the strain gauge 2 penetrates. Then, the lead wire of the strain gauge 2 penetrating the through hole of the receiving plate 7 is soldered to a terminal block (not shown) in a bridge shape. Further, in order to protect the terminal block from wind and rain, a cover 8 is provided on the peripheral end of the receiving plate 7.
Are connected, and the signal line 9 from the terminal block is taken out to the outside. Here, a through hole, through which the screw 6 for applying a compressive load acts in the axial direction of the ring 1 described above, is formed on one end surface of the cover 8 and functions as a locking portion.

The deforming device according to the first aspect includes the compression device 3 and the screw 6, and the end plate portion 3a constituting the compression device 3 has a circular shape as in this embodiment. The present invention is not limited to this, and may be formed in, for example, a rectangular shape or a polygonal shape. Next, a mounting method and an operation of the weight sensor will be described with reference to FIG. First, the shaft portion 3b of the compression device 3 is passed through the ring 1 and the receiving plate 7, and the screw 6 is temporarily fixed to the screw hole 3d at the end thereof via the cover 8.
Then, after applying an adhesive on the strain gauge 2 attached to the outer peripheral surface of the ring 1, the ring 1 is inserted into a frame such as a tank or a hole 10a formed in the leg 10. Thereafter, as the screw 6 is tightened, the distance between the end of the shaft portion 3b and the screw 6 is reduced, and a compressive load is applied to the ring 1 via the end plate 3a. Then, since the ring 1 contracts in the axial direction and extends in the radial direction, the strain gauge 2 is pressed against the inner peripheral surface of the hole 10a by the ring 1, and all the strain gauges 2 attached to the outer peripheral surface of the ring 1 are bored. The inner peripheral surface of 10a is evenly contacted.

Further, the compression device 3 protects the weight sensor and prevents the weight sensor from dropping out of the hole 10a.
The end plate 3a protruding from the hole 10a via the screw 5 and the cap 4 covering the ring 1 are attached to the screw hole 3c formed in the end plate 3a, and the signal line 9 is connected to an amplifier (not shown) for measurement. I do. FIG. 3 shows a gantry or leg 1 for a tank or the like.
0 shows a state of strain or stress generated around the hole 10a opened when a load (weight) is applied from the upper portion to 0, from which a compressive stress is applied in the vertical direction and a tensile stress is applied in the horizontal direction. It can be seen that stress is acting.

In this way, each strain gauge 2 attached to the outer peripheral surface of the ring 1 is pressed by the ring 1 against the inner peripheral surface of the base 10 such as a tank or the hole 10 a formed in the leg 10. Since the strain gauges 2 make uniform contact, it is possible to reduce the strain detection error and the difficulty of temperature correction caused by the strain gauges 2 not making uniform contact. Further, since a compressive load is applied to the ring 1 in the axial direction so that the ring 1 is elastically deformed in the radial direction, it is not necessary to strictly control the dimensional accuracy of the hole 10a into which the ring 1 is inserted. The sensor can be installed easily.

In this embodiment, a structure is employed in which a compression load is applied in the axial direction of the ring 1 by the compression device 3 including the end plate 3a and the shaft 3b.
In order to apply the compressive load, the present invention is not limited to such a configuration. For example, a configuration may be employed in which washers contacting both ends of the ring are connected by bolts to apply the compressive load. That is, any mechanism may be used as long as it applies a load such that both ends of the ring are brought closer to each other.

[0016]

As described above, according to the first aspect of the present invention, a ring to which a plurality of strain gauges are attached is formed from an elastically deformable material, and a compressive load is applied from the axial direction of the ring. Because it is configured to include a deforming device that elastically deforms the ring in the radial direction so that the strain gauge is pressed against the inner peripheral surface of the hole, for example, various storage silos,
When measuring the weight by inserting a ring into the hole provided in the base or leg of a hopper, tank, etc., each strain gauge evenly contacts the inner peripheral surface of the hole. The accuracy of weighing the measured object can be improved. In addition, since the strain gauges are evenly contacted with each other, a temperature correction corresponding to a change in ambient temperature can be performed with high accuracy. From this viewpoint, the weight measurement accuracy of the measured object can be improved. . Furthermore, after inserting the ring into the hole, a compressive load is applied to the ring in the axial direction, and the ring is elastically deformed in the radial direction, so that it is not necessary to strictly control the dimensional accuracy of the hole into which the ring is inserted. Installation of the weight sensor is facilitated.

According to the second aspect of the present invention, the outer peripheral surface of the ring is formed into a tapered surface, so that the ring is inserted into a hole formed in a frame or a leg of a storage silo, a hopper, a tank, or the like. This facilitates the installation of the weight sensor in a shorter time. According to the invention as set forth in claim 3, the deforming device screws a screw, which is locked to a locking portion provided separately from the deforming device, into an end of the shaft portion penetrating in the axial direction of the ring, Since the compression load is applied by tightening the screw, the ring can be elastically deformed only by tightening the screw.

According to the fourth aspect of the present invention, since the cap is attached to the end plate, the weight sensor can be protected and the weight sensor can be prevented from falling off.

[Brief description of drawings]

FIG. 1 shows the structure of an embodiment of a weight sensor according to the present invention, wherein (a) shows a front view of the sensor and (b) shows a side view of the sensor.

FIG. 2 is a diagram showing a mounting structure of the weight sensor according to the first embodiment;

FIG. 3 is a diagram showing strain or stress around a hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ring 2 Strain gauge 3 Compressor 3a End plate part 3b Shaft part 4 Cap 5 Screw 6 Screw

Claims (4)

[Claims] A ring having a substantially cylindrical shape and a plurality of strain gauges attached to an outer peripheral surface of the ring;
A weight sensor that inserts the ring into a hole formed at a location where the weight of the measured object acts and measures the weight of the measured object based on the strain detected by the strain gauge, wherein the ring is elastically deformable. Formed from a variety of materials,
A strain characterized by including a deformation device that applies a compressive load from the axial direction of the ring to elastically deform the ring radially so that the strain gauge is pressed against the inner peripheral surface of the hole. Structure of a weight sensor using a gauge. 2. A ring according to claim 1, wherein said ring has a tapered surface at its leading end when inserted into said hole so that its outer diameter is smaller than its rear end. Item 6. The structure of a weight sensor using the strain gauge according to Item 1. 3. The deforming device includes an end plate abutting on one end of the ring, and a rod-shaped shaft connected to the end plate at a substantially right angle and penetrating in the axial direction of the ring. And a screw locked to a locking portion provided separately from the deformation device is screwed into a shaft end opposite to the end plate portion, and a compressive load is applied by tightening the screw. The structure of a weight sensor using a strain gauge according to claim 1, wherein the weight sensor is configured to perform the following. 4. A structure of a weight sensor using a strain gauge according to claim 3, wherein a cap covering the end plate portion and the ring protruding from the hole is attached to the end plate portion.