SU748710A1 - Thermoelectric apparatus for testing for uniformity - Google Patents

Description

The concept is related to measurement technology and can be used in industry for input control on the uniformity of blanks, as well as for the perusal test for the identity of semi-fab-grats.

Ultrasonic, X-ray, resistive, and other installations of materials for testing heterogeneity 1 are known.

The installations are unsuitable for detecting deformed sections 1 and segregation G with an impurity concentration of 0.1-0.01 at.%. High melts: metals (molybdenum, tungsten,) rhenium, chromium, and others) become brittle when they contain less O gas, 1-0.01 at.%. For & TOE, a defect appears in the manufacture of datas from refractory sheets with the slightest deviation from the production technology of sheets and parts. In this connection, it became necessary to develop a plant for testing sheets for uniformity of distribution of deformed areas and for mixtures in the range of 0.1-0.01 at.%. At least one possible concentration of impurities

detect in metals on installations whose principle of action is based on the measurement of thermoEMF. -, A known installation registers the distribution of inhomogeneities only on wires 1x and is unsuitable for factory conditions.

Thermoelectric devices are known for testing sheet metal of uniformity of zinc coating thickness and for determining the carbon content in steel. In installations there is a KJieisiMi heater, measuring device 2 hours

The thermoelectric device 3 is known, chosen as a prototype, containing a temperature gradient creation unit, made in the form of a copper probe at 60-100 0 and a thermoelectric power measurement unit, the probe, is in contact with the steel surface under test. Therefore, a temperature gradient is created along the normal to the surface, and thermoEMF occurs, depending on the distribution of carbon in the near-surface layer. The thermoEMF is measured with a galvanometer connected to a copper probe circuit - a part-lead wire.

The disadvantage of the prototype is low sensitivity (0.5-1 at.%), Due to the fact that the device measures the total thermoelectric power, consisting of the noise thermoelectric power of the steel-copper pair (14 µV / deg) and the useful thermoEMF of steel-decarbonized steel (12 µs / 1rad). Since the useful signals are ten times less noise, the useful thermoelectric power. on which the homogeneity of the metal surface is judged, is measured with an error of 20-30%. When replacing the copper probe, errors remain due to the instability of the thermal contact. Therefore, the installation prototype is insensitive to the detection of local chemical inhomogeneities with

-4 -2

a concentration of impurities of 10–10% at., as well as inhomogeneities in the work hardening.

The purpose of the invention is to increase the sensitivity to detection of inhomogeneities,

This goal is achieved by the fact that in a thermoelectric plant for testing sheets for uniformity containing a temperature gradient creation unit and a thermopower measurement unit, the temperature gradient creation unit is made of hot and cold heat conductors, each of two symmetrical halves: a movable top mounted on a calibrated spring and fixed bottom. At the same time, the test and reference sheets are clamped between the ends of the heat pipes, between which in the cold heat pipe area there is a terminal consisting of two copper foils with an insulating layer between them, to which the measuring device is connected.

The use of heat pipes consisting of two symmetrical halves eliminates a temperature gradient normal to the test sheet. This reduces the noise thermopower, 10.0 times.

The use of a calibrated spring ensures constant heat flow. The terminal of two glued foils, due to its small thickness and location between the test and reference sheets, does not give noise thermoelectric power. All of this, in general, ensures the sensitivity of the installation to local deformations and is up to lOV-lO at.%.

 On figl depicts the proposed installation, section; 2, the same section A-A.

In Fig.1,2 |;

1.2 — upper and lower half of the hot heat conductor, respectively; 3.4 — the upper and lower halves of the cold heat conductor, respectively; 5; 6 — calibrated spring; 7 - test sheet; 8 - reference sheet;

9 - table of isolator; 10 - insulating insert in a calibrated spring; 11 - screw; 12 - scale of effort; 13 - heating liquid; 14-15. terminal glued from two copper J foils; 16 - insulation layer; 17 - measuring device; 18-19 screws; 20 - coolant.

The proposed installation consists of a temperature gradient creation unit (parts 1-4) and a thermopower measurement unit (parts 14-17),

The installation works as follows. Fluids 13 and 20 circulate through the heat pipes (the fluid flow is indicated by a dotted arrow), creating a temperature of 100–200 s at the ends of the hot heat conductor, and temperatures of 20–170 ° C at the cold ends. The strip from the reference material, recognized by all indicators as the best,

0 is placed on the ends of the lower halves of heat pipes under terminal 14-15, the test sheet 7 is placed on top, The degree of pressing of the ends of the upper halves is adjusted by screw 11 along

5 scale 12 Heat pipes are insulated by weight. Therefore, thermopower is supplied to the device 17, depending on the temperature gradient along the sheets and the magnitude of non-uniformity in the test area of sheet 7: Since

. the pressing force of the half of the heat pipes and the currents of the circulating liquids are constant, the thermoEMF value is proportional to the strain. of the test area, or the accumulation of impurities, in it. The ends of the contiguous halves of heat pipes differ in temperature by no more than 0.01-0.02 ° C, and the terminal thickness does not exceed 0.05-0.1 mm,

Therefore, the thermopower thermopower of the copper test metal is small and is 3-5% of the thermopower values corresponding to impurity concentrations of 10,%. This allows

5 to apply a highly sensitive device, for example, a low-resistance galvanometer, to measure thermoEMF

By reducing the noise level of the myEDL, the sensitivity of the installation to the detection of inhomogeneities is increased. Areas of the test sheet containing significant heterogeneity are marked and discarded in the production of parts. Analysis of one 5 plots requires 1–5 min, in the range of sheet thicknesses from 0.05 to 0.5 mm,

A thermoelectric unit for testing uniformity sheets 0 has the following advantages over known units:

a) the sensitivity of the proposed installation exceeds the sensitivity of the installation of the prototype. 10-100 times;

Claims (1)

SUMMARY OF THE INVENTION A thermoelectric installation for testing sheets for uniformity, comprising a unit for creating an ed temperature gradient and a unit for measuring thermoEMF, in order to increase the sensitivity to detecting inhomogeneities, the unit for creating a temperature gradient is made of hot and cold ¹⁵ heat conductors, each of two symmetrical half-movable upper, mounted on a calibrated spring, and fixed lower, moreover, the test and reference sheets, between which region cold heat conductor terminal is composed of two copper foils with an insulating layer between them, to which is connected a measuring device,