SU1492212A1 - Method of calibrating displacement transducer - Google Patents

Abstract

This invention relates to methods for calibrating displacement sensors. The aim of the invention is to improve the accuracy of the calibration of sensors designed to operate in conditions of elevated or lowered temperatures. Calibration is carried out using an elastic sample 1 with a sharp notch or crack. The working bodies of the sensor 6 is installed on the sample on opposite sides of the notch. The control relative positions of the working parts of the sensor are obtained by a discrete change in the displacement of the reference sample by its stepwise loading or unloading. The offset values at the calibration temperature are determined by calibrating the reference sample at room temperature, taking into account the correction for the temperature change of the elastic modulus of the sample material ΔT ₃ = ΔT ₀ (E _T / E _T ), where ΔТ ₀ and ΔT ₃ are the displacements corresponding to the same load level at room temperature and calibration temperature respectively

E _T0 and E _T3 is the elastic modulus of the sample material at room temperature and calibration temperature, respectively. The method makes it possible to calibrate displacement sensors of any type at an arbitrary given temperature and in various test environments. 1 hp ff, 2 ill.

Description

eight

F1a.1

Tantalized on the sample on opposite sides of the notch. The control relative positions of the working parts of the sensor are obtained by a discrete change in the displacement of the reference sample by means of its stepwise loading or unloading. The displacement values at the calibration temperature are determined by calibrating the reference sample at room temperature, taking into account the correction for the temperature change of the elastic modulus of the sample material utj

 bt (Et, / Et,), where utg and utj are the displacements corresponding to the same load level at room temperature and calibration temperature, respectively;

Ej and E 4. modulus of elasticity mate ° - „

The sample sample at room temperature and calibration temperature, respectively. The method makes it possible to calibrate any type of movement sensor at an arbitrary temperature and in various test media. 1 z.p, f-ly, 2 silt o

The invention relates to methods for calibrating displacement sensors, in particular to methods for calibrating displacement sensors primarily used in materials testing for crack resistance, under conditions of temperature that differ from room temperature.

The purpose of the invention is to improve the accuracy of the calibration of sensors intended for operation in conditions of elevated or low temperatures.

1 shows a diagram of the implementation of the method; in Fig „2 - the calibration curve obtained using the method at elevated temperature.

Calibration device is made in the form of an elastic sample 1, for example, from high-strength steel with a sharp notch. On sample I, on one side of the notch, an attachment 2 is mounted for mounting a measuring instrument 3, for example a dial indicator. On the opposite side of the notch on the sample, the stop A for the movable brush 5 of the indicator 3 is attached. The tooling 2 is made in such a way as to ensure the measurement of the displacement of the sample halves during calibration along a line parallel to the vector of the applied force P and as the measuring axis of the sensor. For sensor 6, for example, inductive, the axis is the central axis 0-0 of the inductance kits and plunger 7. For this purpose, the snap-in 2 for mounting the sensor 6 and the indicator 3 is made in the form of a single piece in which 6 and the installation rod 8 of the indicator 3 are made coaxially in a single pass of the cutting

The tool stop 4 simultaneously serves to support the installation of the sensor plunger 7.

The method is carried out as follows.

The equipment 2 and the support 4 (on either side of the notch) are mounted on the sample 1 and the indicator 3 is fixed in the equipment by fixing the adjusting rod 8 of the indicator 3 by a stop screw

9. Then, in the equipment 2, the sensor body 6 is installed and secured in such a way that the plunger 7, pressed by the stop 4, is fixed in the neutral position corresponding to the zero signal of the sensor. The sample is loaded at room temperature with a discretely increasing force, and at each step of loading PJ, the displacement amount of sample C (L;) o over the indicator and the corresponding signal from the sensor (U;) are recorded. The result is a series of data load - sample displacement - sensor signal, the indicated operation

At the same time, the sample is calibrated, - (u;) t and the sensor is calibrated at room temperature (Ul) te- (u;) to Sample 1 is unloaded, indicator 3 is removed from snap-in 2 and the sample with the sensor is placed in the test chamber. In the chamber, predetermined temperature conditions are created, after which the sample is again loaded with the same sequence.

force P, as at room temperature, and recorded at each stage of the load PJ sensor reading (Uj). To test the sensor's reverse stroke, the load from the sample is reduced § 1 II

ho

t

100

X

T 2 (Yu

Claims (2)

Claim 1 о The method of calibration of the displacement sensor, according to which the working bodies of the sensor are fixed on the calibration device, the device is loaded, the movement of the working bodies of the sensor is fixed with a movement indicator and in each of their positions 5 a signal from the sensor is recorded, characterized in that, in order to increase the accuracy of calibration of the sensors, designed to work in conditions of elevated or lowered 10 temperatures, the calibration · device is performed in the form of an elastic sample, while working x of the sensor organs and registration of the signal from the sensor, register the magnitude and step of the applied load, disconnect the displacement indicator, expose the sensor together with the elastic sample to temperature influence, load the sample according to the same procedure, record signals from the sensor, determine the displacements of the working parts of the sensor taking into account corrections for the temperature change in the elastic modulus of the material 25 of the elastic sample. 2, The method of pop. 1, characterized in that the elastic sample is made with a sharp notch, the parameters of which are in the ratio of 30 b,. 1 ^ ^where 1 “I have ^{3111113 notches} , b is the gross section width, t is the thickness of the sample. FIG. g