JPH0781813B2 - Strain gauge device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a strain gauge, and more particularly to a structure of a strain gauge device suitable for use at high temperatures.

<Prior art and its problems> It is known that a strain sensitive element of a thin metal grid is attached to an object in order to measure strain. This strain-sensitive element measures the magnitude of strain inferred from the change in electric resistance in the element due to strain. The measurement of the temperature received by the strain gauge grits should be performed at the same time for the measurement under the high temperature condition, and the present invention provides an apparatus suitable for measuring the strain under high temperature.

In the conventional device, it was difficult to say that the strain measurement by the strain gauge included the problem of elongation due to the temperature of the strain gauge material and that the temperature was necessarily corrected appropriately.

<Object of the Invention> An object of the present invention is to provide a strain gauge device capable of displaying the correct strain of an object whose temperature condition has been corrected even at a high temperature.

<Outline of Means> In short, the present invention connects two sets of lead wires A and B to the strain gauge, one set functions as a thermocouple, and the other set measures an electric value due to strain of the strain gauge. A set of lead wires is provided, the other ends of these lead wires are connected to a measuring device including a voltmeter and a voltage source data storage device, and the influence data due to temperature is measured without distortion and this data is stored. The strain gage device is characterized in that it can be input to a storage device and a correct strain value of an object at a high temperature can be measured.

<Embodiment> In the device for carrying out the present invention, the strain gauge is connected to a measuring device provided at a position apart from a position for emitting a signal from temperature and electric resistance of the device, and the strain-sensitive device and the calculating device Are connected by two independent sets of leads, each set of leads having a similar configuration, with at least one set having its terminals connected so as to form a thermocouple and two sets of leads. The wires are similar to each other, but the two leads of one set are connected to a voltage source and the two similar leads of the other set have a voltage with a resistance greater than that of the device. Connected to the meter.

It is necessary to detect the temperature of the element at the time of strain measurement, so that it can be measured at the same time as the strain measurement, and correction of the temperature measurement can be given to the strain measurement value before displaying the strain measurement of the object. is necessary. Therefore, it is essential that the resistance change of only the temperature change of the element is performed before the strain measurement without applying the strain. The values obtained by this calibration (calibration correction, measurement value correction) must be loaded into the equipment so that they can be used for correction when the strain gauge is implemented. A calculation device including a data storage device immediately gives a corrected value to the measured value of the strain gauge so that the actual strain value can be read.

This corrected value is added to the "apparent strain value" based on the difference in the expansion coefficient between the measurement object and the strain gauge. When carrying out the calibration, both the material and the strain gauge attached to the material are heated by a heating means that can be set to the conditions for measurement. The change in the electric resistance is displayed simultaneously, that is, the effect of heat that directly heats the material and the one that is based on the difference in thermal expansion between the material and the strain gauge. These heat effects are subtracted in the calculation device when the strain gauge is actually used, and the correct strain of the material can be displayed. Next, an embodiment of the present invention will be described with reference to the drawings (FIG. 1).

A strain response element (strain gauge) (hereinafter referred to as an element) of a conventionally known type is denoted by reference numeral 1 and has terminals 2 and 3, which are connected to lead wires.

Element 1 is connected to a computing device in the form of a data storage device that is computer controlled by two sets of leads A, B. The two sets of lead wires are housed in a heat resistant sleeve made of a high temperature inorganic material. If the strain gauge is used, for example, in a boiler system, these leads will be of long length. The two sets of lead wires are similar, and the case where the lead wire A is made of a material different from that of the lead wire B is included. At terminals 2 and 3, lead wires A and B are joined together to form two thermocouple pairs. The calculation means can switch from one thermocouple set to another thermocouple set without affecting each other, and only one thermocouple set can be used. (In the drawing, the voltmeter and the voltage supply reduction are shown only for one set.) In the calculation device 4, one set of the lead wires A is a current in the lead wire A in order to minimize the influence of the resistance of the lead wires. Is connected to the micro voltmeter 5 that has a high resistance that can be ignored. The signal of the micro voltmeter 5 is determined by the effect of the voltage supply source 6, and from the signal, strain (distortion value) in the element 1 is obtained.
Is estimated.

In use, the element is secured to the object to be strained (not shown) by ceramic cement, spot welding or other means. The strain produced in the object affects element 1, but the electrical resistance is influenced by what is known as "apparent strain" due to changes in temperature. These result from elongation due to the difference in the coefficient of thermal expansion between the object and the element.

As described above, the element is fixed to an unstrained material (object) before use, and the resistance change of the element at the temperature to be subjected to the test is measured in advance.

<Effects of the Invention> In this way, the resistance change caused by the apparent strain and the resistance change directly related to the temperature are recorded, and when the element 1 is used, these inappropriate resistance changes are displayed by the calculation device. Removed from. The temperature measuring point should be mounted as close as possible to the strain measuring point of the element. These measuring systems have a very low thermal inertia (corresponding to the inertia of the moving solids), which is desirable in the case of high temperature transition slopes.

By carrying out the present invention, the strain measurement error due to the temperature effect is eliminated, and the strain gauge can be used for an object under high temperature to measure the strain.

[Brief description of drawings]

 FIG. 1 is a schematic wiring diagram showing the structure of the apparatus. 1 …… Element (strain gauge) 2,3 …… Terminals A, B …… Lead wire 4 …… Calculator 5 …… Micro voltmeter 6 …… Voltage supply source

Claims (3)

[Claims] 1. A strain response element is connected to a computing device at a position remote from the strain response element, and an indication of strain indicates the electrical resistance of the strain response element and the temperature at a fixed position of the strain response element. The response element and the computing device are connected by two separate leads, each lead having a similar configuration, wherein at least one lead forms a thermocouple. , One set of two similar leads connected to a voltage source and the other set of two similar leads connected to a voltmeter having a higher electrical resistance than the strain responsive element. Strain gauge device. 2. The strain response element is pre-calibrated without distortion, and the calibration is input and stored in the computer. The strain gauge device according to item 1. 3. The strain gauge device according to claim 1 or 2, wherein the calculation device includes a data storage device.