RU2306553C1 - Thermal electric pulse device to control the non-uniformity of the metals and alloys surface layer - Google Patents

Abstract

FIELD: instrument making industry; metallurgy; production of the thermal electric pulse devices used for control of the non-uniformity of the metals and alloys surface layer.

SUBSTANCE: the invention is pertaining to the means of the nondestructive control. The thermoelectric pulse device contains the sharp-point probe, the source of the pulse current created by the capacitor discharge through the discharge electrode, the meter of the thermal electromotive force and the switch for the electromotive force sign change, the measuring electrode connected with the thermal electromotive force meter and the mobile electrode connecting in turn the circuits of the capacitor discharge and measurement. The technical result is the increased accuracy of determination of the non-uniformity of the metals and alloys surface layer due to decrease of the depth of the heating penetration of the surface layer.

EFFECT: the invention ensures the increased accuracy of determination of the non-uniformity of the metals and alloys surface layer due to decrease of the depth of the heating penetration of the surface layer.

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Description

The invention relates to non-destructive testing, and more specifically to devices designed to measure the heterogeneity of the surface layer of metals and alloys, and can be used in enterprises of the engineering industry and in scientific research.

Known thermoelectric device for monitoring metals and alloys containing cold and hot electrodes, relays, a variable resistor, transformer, timer, included in the circuit to create a temperature gradient [1]. The constant force of pressing the hot electrode to the controlled product is provided by an electromagnet with a winding.

However, the disadvantage of this device is a significant variation in the response time of the electromechanical relays, which reduces the accuracy of the control due to the different duration of the current pulse, leading to a variation in the thickness of the heating zone.

The closest technical solution to the invention by its technical essence is a thermoelectric device for controlling the heterogeneity of alloys containing a probe, a current source, a thermoEMF meter and a thermoEMF sign switch [2], in which a current transducer, current and voltage meters are provided to increase the resolution and accuracy. This device is taken as a prototype.

However, in this device, a pulsed current flows in the probe localization region, the pulse duration of which is half the period of the alternating voltage of the network, i.e. 10 ms, in the intervals between which the measuring device is switched on. In this case, the heating of the sample goes to a great depth, which leads to the measurement of the integral over the thickness of the penetration of the heat flux of thermoEMF. Therefore, this device cannot be used to control the heterogeneity of a thin surface layer, in which the generated thermoEMF is very different from the thermoEMF generated in the thickness of the material at the same temperature difference.

The problem to which the invention is directed, is to increase the accuracy of determining the heterogeneity of the surface layer of metals and alloys by reducing the depth of heating of the surface layer.

For this, a thermoelectric pulse device for controlling the heterogeneity of the surface layer of metals and alloys containing a probe, a thermoEMF meter and a thermoEMF sign switch, in contrast to the prototype, is equipped with a pulsed current source generated by a capacitor discharge through a discharge electrode, a measuring electrode connected to a thermoEMF meter and a moving electrode, which closes alternately capacitor discharge circuit and measurement.

The invention is illustrated in the drawing, which shows a diagram of the proposed device.

The device contains a pointed probe 1, pressed into the housing 2, mounted on a sample 3, a transformer 4, acting as a power source for charging a capacitor 5 through a rectifier diode 6 and a resistor 7, a voltmeter 8 for monitoring the capacitor charge voltage, a key 9 for decoupling the processes time the charge and discharge of the capacitor, the discharge electrode 10, the movable electrode 11, held in the initial upper position by the stop 12, the stationary measuring electrode 13, the connecting wire 14, the load 15, providing the necessary force rizhatiya movable electrode to the measuring, the damper in the form of resilient plates 16, 17 thermoelectric power meter, mark thermoelectric switch 18, a frame for fixing the fixed elements of the device 19.

The device operates as follows. A pointed probe is mounted on the sample. Before starting the measurement, the key 9 closes. The stop 12 holds the movable electrode in the upper position I. Then the key opens, turning the stop releases the movable electrode, which, under the weight of the load, drops to position II, where it is held by the damper 16. In the direction of the move of the movable electrode, it contacts the discharge electrode. At the moment of contact, the circuit closes: discharge electrode - moving electrode - connecting wire - probe - sample, and a current pulse of the capacitor discharge flows, which heats the region of the material under the probe, creating a temperature gradient. When the movable electrode reaches position II, the circuit closes: measuring electrode - damper plates - movable electrode - connecting wire - probe - sample - thermopower meter, and the value of the thermopower being studied is recorded.

The pulse duration of the capacitor discharge current is determined by the contact time of the discharge electrode and the movable electrode, which depends on the speed of the latter, and amounts to tenths of a millisecond.

This device allows to increase the accuracy of determining the heterogeneity of the surface layer of metals and alloys by reducing the penetration depth of the thermal pulse by adjusting the discharge time of the capacitor, which leads to a decrease in the thickness of the controlled layer.

Sources of information taken into account during the examination

1. Patent No. 2134875 of the Russian Federation, IPC G01N 25/32. Thermoelectric device for monitoring metals and alloys [Text] / S.F. Korndorf, Yu.I. Nesterovich. - Publ. 08.20.99, Bull. Number 23.

2. USSR author's certificate No. 636518, IPC G01N 25/32. Thermoelectric device for controlling the heterogeneity of alloys [Text] / Yu.A. Bratashevsky, V. M. Vasilkov, N. A. Doroshenko - Publ. 12/05/78, Bull. No. 45 is a prototype.

Claims (1)

Thermoelectric pulse device for controlling the heterogeneity of the surface layer of metals and alloys, containing a probe, a thermoEMF meter and a thermoEMF sign switch, characterized in that it is provided with a pulse current source generated by a capacitor discharge through a discharge electrode, a measuring electrode connected to a thermoEMF meter, and a movable electrode, closing alternately capacitor discharge circuit and measurement.