SU970088A1 - Eddy-current device for touch free measuring of dimensions - Google Patents

Description

(54) SWITCHING DEVICE FOR BECKOHTPJCTHORO DIMENSION MEASUREMENTS

one

The invention relates to instrumentation engineering and can be used for contactless measurement of the dimensions of electrically conductive products by the eddy current method.

Eddy-current devices for measuring dimensions are known, comprising an alternator, two overlapping electromagnetic transducers arranged coaxially and rigidly connected to each other, and a series-connected adder, compensator, alternating current amplifier, detector and indicator 1.

These devices have an insufficient accuracy of measurements during transverse movements of products in the area of a contact.

It is also known to have a linear device for measuring linear dimensions containing an alternating current generator, two electromagnetic transducers, rigidly interconnected between themselves and installed coaxially, two signal processing channels, each of which is connected to one of the transducers and consists of a series-connected compensator, amplifier N current, detector and

functional converter, adder and indicator 2.

A disadvantage of this device is the small range of measuring the dimensions of cylindrical articles.

The closest to the invention in its technical essence is an eddy current device for contactless10 measurement of dimensions, containing an alternating current generator, connected to it, an overhead electromagnetic transducer, located coaxially at a fixed distance from one another, connected to the transducer measuring coils connected in series with an adder, a compensator, an AC amplifier, a detector and an indator, and a mechanism for moving transducers with a drive.

 The drive of the movement mechanism in the known device is made in the form of a control unit, the input of which is connected to the output of the detector and the power amplifier 3.

This device has insufficient measurement reliability. since the drive of the movement mechanism is complicated in

30 manufacturing and operation due

high demands for accuracy and stability.

The purpose of the invention is to increase reliability.

This goal is achieved by the fact that in an eddy-current device for: contactless measurement of dimensions, containing an alternating current generator, two superimposed electromagnetic transducers connected to it, located coaxially at a fixed distance from each other, connected to measuring coils. , an AC amplifier, detector and indicator, and a movement mechanism for converters with a DRIVE, a drive mechanism for movement of converters made in the form of an additional alternator and frequency cola. The main f, (., "and additional drrGen € tors are chosen from the condition

.ОЗ о „. (,

The drawing shows a functional diagram of an eddy current device for contactless measurement of dimensions, - ..

The DEVICE contains an alternating current generator 1, electromagnetic transducers 2 and 3, the field-generating coils 4 and 5 of which are connected to the generator 1, and the measuring coils b and 7 are connected to the input of the adder 8, connected in series to the compensator 9, the amplifier 10 of the alternating current, the detector 11 and the indicator 12, a transducer movement mechanism 13 and a movement mechanism drive in the form of an alternating current generator 14. Electromagnetic transducers 2 and 3 are made identical, arranged coaxially, separated from each other by a distance I exceeding the maximum measured diameter of the product, and are rigidly connected: to each other by means of a bracket 15. The moving element 16 of the moving mechanism 13 is rigidly connected transducer housings placed on both sides of the monitored piece 17. The axes of the transducers 2 and 3 are perpendicular to the longitudinal axis of the product.

The device works as follows.

The wood-generating coils 4 and 5 are powered by / from the generator 1 by alternating current with a frequency of 17 induction in the product 17 eddy currents, the electromagnetic field of which causes the appearance in the measuring coils b and 7 of the applied voltages. The voltage from cat uca b and 7 is summed by adder 8, the voltage Ug from which is compensated by compensator 9, for example, by installing both transformers on the product with the maximum diameter, after which the compensated input voltage Up is amplified by an amplifier

5 10 AC is detected by the detector 11 and is fed to the indicator 12. The transducer movement mechanism 13, controlled by the generator 14, provides transverse movement of the electromagnetic transducers 2 and 3 relative to the product. J17 with frequency P this is about% and / 2 respectively transducers 2 and 3 to the surface of the product change out of phase with the same frequency. When the distances change (Y, and (/ 2, the output voltage Ug of the adder a changes from the minimum value, when one of the preparators has the minimum distance to the surface of the product, up to the maximum value, while the voltages Ug also change and U ,, (j. The detector 11 generates

- a signal proportional to the voltage value of the amplifier 10, and the voltage from the detector output depends only on the diameter of the product under test. Selecting the frequency of the additional generator DRP

0 from the ratio, "0.03, (." Provides the required accuracy of the detector. In most devices, you can use industrial

35 network with a frequency of 50 Hz.

The proposed device provides a measurement of the dimensions of electrically conductive products during their transverse movements in the control zone over a wide range with increased reliability, since the mechanism for moving converters and its drive is easier to manufacture, set up and operate.

45 due to the lack of special requirements for their accuracy and stability.

Claims (2)

1. Dorofeev A, L. and others. Induction on thickness gauges. M., Energie, 1969, p. 104 2. The author's certificate of the USSR 524071, cl. G 01 B 7/02, 1974. 3 "Copyright certificate Ssl 746173, cl, G 01 B 7/12, 1978 (prototype).