JP2013185916A - Strained force measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct large volumetric thermal expansion of liquid, which causes failure, and adjust it to a volumetric thermal expansion coefficient of a container so as to eliminate a pressure fluctuation due to temperature influence, in a hydraulic strained force measurement device enclosing the liquid inside.SOLUTION: Components which have smaller volumetric thermal expansion coefficients than liquid are enclosed inside an airtight container at a certain rate to adjust an average volumetric thermal expansion coefficient inside the container to a volumetric thermal expansion coefficient of the container, thereby eliminating the influence due to thermal expansion. As a result, strained force is measured with high accuracy.

Description

The present invention measures the tension force from the outside surroundings by measuring the hydraulic pressure of the strainable sealed container.

The workpiece on the side receiving the tension force was used as a measuring machine, and strain force due to the tension force was used to measure the tension force using a strain gauge, piezoelectric element or hydraulic pressure.

In an example of a conventional strain meter, FIG. 1, G1, G2, G3, and G4 are attached to the inside of a pair of strain bodies 1 to form a Wheatstone bridge.

When a compressive force is applied from the top and bottom to the center of the pair of upper and lower strain generating parts, compression and elongation strains are generated in each gauge, and the amount of strain is taken out as an electrical signal from the Wheatstone bridge.

In such a configuration, when an urging force is applied from the periphery of the strain generating portion, a force having a component perpendicular to the gauge acts on the strain generating portion, and the beam is distorted by the force pushed from above and below. This signal was regarded as a tense force.

However, there is a problem that the pressure from the entire circumference is represented only by the force in the vertical direction, or the strain force is low and the strain force is large and the strain force is different from the actual strain force. . For this reason, the liquid pressure is sometimes measured by enclosing the liquid in a cylinder capable of generating strain and causing strain by external pressure. The volume thermal expansion coefficient of the liquid is much larger than the metal volume thermal expansion coefficient of the container that also serves as the strain generating part, and the pressure fluctuates greatly even with a slight temperature change, making it impossible to accurately measure the outer peripheral pressure. .

Patent Publication No. Hei 7-308808 Rotational speed and gripping force measuring instrument

In order to solve the above-described problem, the change in pressure due to temperature is reduced by matching the volumetric thermal expansion coefficient of the interior containing the enclosed liquid with the volumetric thermal expansion coefficient of the metal of the container that is the strain generating part.

If a substance with a small volumetric thermal expansion coefficient is mixed in the encapsulated liquid with a large volumetric thermal expansion coefficient, the average volumetric thermal expansion coefficient can be adjusted.

Examples will be described. A container 1 also serving as a strain generating part contains a liquid 2 and an average volume expansion coefficient adjusting component 3, and a pressure gauge 6 is attached via a packing 4-1 to form a sealed structure.

Here, when receiving a pressing force from the outer periphery of the container 1 that also serves as the strain-generating portion, the container 1 that also serves as the strain-generating portion undergoes strain, the internal volume decreases, and the internal pressure pushes the diaphragm of the pressure gauge, The structure is such that the amount of strain, that is, the tension force from the outer peripheral portion, can be measured as the pressure increases.

In order to solve the above-described problem, the change in pressure due to temperature is reduced by matching the volumetric thermal expansion coefficient of the interior containing the enclosed liquid with the volumetric thermal expansion coefficient of the metal of the container that is the strain generating part.

As a calculation example, in the above structure, the container 1 that also serves as the strain generating portion has a stainless volume thermal expansion coefficient of 33 ppm / ° C, the liquid has a glycerin volume thermal expansion coefficient of 500 ppm / ° C, and the average volume expansion coefficient adjustment component 3 has an invar volume heat. When using an expansion coefficient of 2 ppm / ° C, the volume fraction of the substance is
Invar volume fraction
x and the volume fraction of glycerin
If y
33 = 6x + 500y
x + y = 1

From above
x = 467 ÷ 494 = 0.9453…
The volume ratio of the volumetric thermal expansion correction metal invar is about 0.945, and the volume ratio of glycerin is about 0.054.
Each component is vacuum defoamed and heated defoamed to prevent gas mixture, eliminating the effects of gas, and adjusting the ratio of the different volumetric thermal expansion coefficient, the thickness of the packing should be adjusted Is also possible.

It is explanatory drawing of the conventional Example. It is explanatory drawing of the internal connection of the conventional Example. It is an Example of this invention, and cross-sectional explanatory drawing.

DESCRIPTION OF SYMBOLS 1 Strain part 2 Liquid 3 Average volume coefficient of thermal expansion adjustment part 4 Packing 5 Plug 6 Pressure gauge
G1 ~ G4 Electric resistance detection means Strain gauge

Claims (1)

When measuring pressure or pressure by pressure from outside or liquid pressure in a sealed container that can be strained by pressing, place an object with a small volumetric thermal expansion coefficient in the liquid in the sealed container. An apparatus for measuring external pressure and pressure characterized by eliminating the pressure effect due to temperature by making the average volumetric thermal expansion coefficient inside the sealed chamber the same as that of the container.