SU1237963A1 - Device for eddy-current checking of cylindrical non-ferromagnetic articles - Google Patents

Abstract

The invention relates to the field of instrumentation technology and can be used for measuring eddy-ducting by the method of electrical conductivity of cylindrical non-ferromagnetic products. The purpose of the invention is to expand the range of measurement of monitored products by ensuring that products can be controlled by a single transducer of different diameters by taking into account the fill factor of the transducer. The device contains a master oscillator. eddy current transducer (VTP), unit diameter of monitored products, made in the form of a magazine of tanks and connected in series VTP, connected to ECP and diameter unit serially connected transducer signal extraction unit, proportional to the active and inductive resistances introduced by the transducer, the first functional unit implemented the transformation g Xg - tgM, the second functional unit that performs the transformation tg4i-- y, the third functional unit that implements reobrazovanie and dividing unit, also connected to the setting element diameters and generator and performs conversion yuschy 6. When placing a controlled product in the ECP, using the setpoint adjuster, the capacitance is set to compensate for the inductance part of the ECP caused by the gap between the transducer and the product, i.e. provide conditions j 1.1 zp f-ly, 2 ill. I (L 1C with H CD Od 00

Description

The invention relates to a control and measuring technique and can be used to measure the electrical conductivity of cylindrical non-ferromagnetic products using the eddy-current method.

The purpose of the invention is to expand the range of measurement of monitored products by: allowing the control of one transducer of a different diameter by taking into account the fill factor of the transducer,

FIG. 1 shows a block diagram of a device for the eddy-current control of non-ferromagnetic products; in fig. 2 - dependence tgy f (y), where f - the angle characterizing the phase of the magnetic flux inside the product; y is a generalized parameter depending on the electrical conductivity of the product.

The device contains (; it is the master oscillator 1, the eddy current transducer 2 and the preset-connected Chick 3 of the diameter of the tested product, made, for example, in the form of a magazine of capacitances.

To the eddy current probe 2 and the setting device 3 is connected unit 4

neither the signal of the converter, connected also to the generator 1. To the output of the block 4 of the signal extraction of the converter, three functional converters connected in series are connected, 5,6,7, implemented YUTS1X conversion, respectively

h VK f (y) -y; y-y, where R,

s

and..

active and inductive resistances of the eddy current transducer introduced by the controlled product; f is the angle characterizing the phase of the magnetic flux inside the product; y is a generalized parameter depending on the electrical conductivity of the product. The output of the functional converter 7 is connected to the input of the delsh-south dividing unit 8, one input of which divider is connected to the generator and the other to the rear sensor 3.

The device works as follows.

Controlled product 9 is placed in the eddy current transducer 2 (VTP). At the same time the setting device 3 is installed

cast in a position corresponding to the diameter of the test product 9, i.e. a capacitance value is set that compensates for the portion of the inductance of the ECP by which the inductances of eddy current transducers of nominal diameter and diameter equal to the diameter of the product under test differ.

In fact, the setting device compensates for the influence of the air gap between the product and the winding of the eddy current transducer on the output signal of the converter, which is equivalent to reducing the diameter of the ECP to the product diameter, i.e. to the condition Vj 1, where J is the filling coefficient of the ECP of the product.

In each case, the setting device can be graduated in terms of the diameters of the controlled products or in the values of

/

oJ- LCl--)

where C is the setpoint capacity; L - inductance of ECP; u, l is the frequency of the supply voltage.

For example, ECP has para-eters: diameter d, 30 km; inductance L 5 mH; supply voltage frequency uJ 1 kHz.

At this frequency, a change in the diameter of the product leads to a change in / and, accordingly, the capacitance with the setting device and in the following relations:

d mm

28 26 24

0.87 0.75 0.64

C, uF

5.82 6.75 7.91

From the output of the signal extraction unit 4, the inputs of the functional converter 5 receive signals proportional to the values of the applied active and inductive resistances of the ATP, and are converted into a signal proportional to tg y - the tangent of the phase angle of the magnetic flux in the article under study. Functional Converter 6 implements the method of piecewise linear approximation of the functional dependence of the form

2379634

) .22

beiy (bery - beiy) - ber, y (bery + beiy)

where is bery, beiy,

, beiy are mathematical functions whose values are tabulated depending on y.

Graphically, this functional dependence is presented in Fig.2.

The output of converter 6 is a signal proportional to the generalized parameter y.

The functional transducer 7 converts the signal into a signal proportional to y.

The inputs of dividing unit 8 receive signals from generator 1, proportional to the frequency s) of the supply voltage, from setpoint 3, a signal proportional to the dianometer d of the monitored product, and from functional converter 7, a signal proportional to y.

The division unit performs the division operation according to the expression

&

Lee

.d

where B is the electrical conductivity of the controlled product; f- - magnetic constant, and at the output of the dividing unit a signal is obtained that is proportional to the electrical conductivity of the monitored product.

Claims (2)

1. A device for eddy current testing of cylindrical non-ferromagnetic products, comprising a master oscillator, an eddy current transducer and a signal injection unit of the transducer connected to it, under Connected to a master oscillator, characterized in that, in order to expand the measurement range of monitored products, it is equipped with a gauge of the diameter of the monitored product and connected between an eddy current transducer and a transducer signal extraction unit connected to the latter by three successively connected functional converters that perform the conversion R -Rh tgif f (y) - y; "R. Rh active and inductive resistances of the eddy current transducer supplied by the controlled product, selected by the transducer signal extraction unit; H - the angle characterizing the phase of the magnetic flux inside the product; V is a generalized parameter depending on the electrical conductivity of the product, and a dividing unit, one input of the divider which is connected to the master oscillator, and the other input of the divider is connected to the unit of the diameter of the product under test. 2. The device according to claim 1, 1 and 2, and the fact that the unit of control of the diameter of the controlled product is made in the form of a magazine of containers. Editor N.Shvydka Compiled by I.Keso n Tehred M.Hodanich Order 3282/44 Circulation 778 Subscription VNISHI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 Fi8. 2 Proofreader A. Obruchar