SU1448260A1 - Method of determining electric and magnetic parameters of cylindrical articles - Google Patents

Abstract

The invention can be used for nondestructive testing of magnetic permeability and specific electrical conductivity of dilindrical ferromagnetic products with transducers. The method of determining the electrical and magnetic parameters is implemented in the device. In a cylindrical ferromagnetic product (CPMI), placed in the pass-through ferromagnetic transducer 1, a uniform axisymmetric alternating magnetic field (PMP) excites eddy currents. At the same time, the voltage is measured, independent of the properties of the CPMI. Then, the current value of the relative applied voltage, which is a complex signal, is determined, and the actual component is extracted from it. Further, the frequency of the MFR excitation current is changed, until the maximum value of the actual component of the relative applied voltage is obtained and registered. The value of magnetic permeability is determined, the frequencies of the initiating current of the SMP are reduced until the actual co-ratio (- the relative input voltage does not decrease in size). in the description of the invention. The device comprises a controlled voltage generator 6, an amplitude detector 7, dividers 8, 13, blocks B 9, 10 sampling-storage, B 11, 14 comparison, switch 12, computation B 15, conversion 16 Tel frequency voltage, a delay line 17, the differential;.. cial circuit 18, a comparator 19, genera- tors 20 write pulse method has a high measuring accuracy yl 2 w (A..

Description

com 14 comparison. The frequency of the generator by the 15 field field of two different frequencies, 6, increases until the registration of the relative insertion of the first output of the BS 14 is signaled at both frequencies, about —––––– p and c. the fact that, with the target signal at the output of a BVH 9, there is no less improvement in the accuracy of the method, which is equal to or higher than the maximum sign

recorded in BVH 10, which enters BS 14 through KOM 12. When this condition is fulfilled, first, the voltage on the BVH 10 proportional to the maximum Keirz is changed to 25 before reaching the block 15, - secondly, the commutator maximum of 12 is connected to the input of the BS; 14, the output of the D 13, and hence the half value of the max. arrives at

the input voltage is reduced by oi compared to the registered value, and the corresponding frequency of the homogeneous alternating axially symmetric field is recorded, and the initial magnetic permeability and electrical conductivity of the tested product are determined from the ratios

40

Max Wade See) Mr. MaKcFeTJ | 5 N7T

relative voltage applied, the value of which is recorded, and then yin {diminishes the frequency until the input of BS 14, thirdly, BS 14 transfers 30 when the actual component is used to drive the VCO 6 to fourth, block 15 calculates the value of the magnetic permeability fu by the relation (4). Thereafter, in BS 14, the actual component of the output BVH 9 is compared with half its maximum value. B

the moment of equality of these values of BS 14 generates a signal to prohibit a change in the frequency of the VCO 6. This signal from the output of the converter 16 to the block 15 receives a voltage equivalent to the frequency of the excitation current. This signal, through a gap, determined by the time of frequency conversion to voltage in PCF 16, through the delay line 17 is fed to the control input of unit 15, allowing the calculation of the value of specific electrical conductivity G by the relation (8). In this case, block 15 can be executed in the form of an analog or digital processor (in the latter case, the corresponding A1SC is installed on its analog inputs), working according to the described algorithm.

In the proposed method eliminated a number of methodological errors, GHS 1

pjUoWzR

45

50

55

where IU and (J are, respectively, the initial magnetic permeability and specific electrical

the conductivity of the controlled product; idts (M) - relative contributed

voltage;

N is a generalized parameter; Nj, is the value of the generalized parameter corresponding to the frequency Q of the homogeneous variable axis {electric magnetic field, at which

of the applied voltage, its real component is selected, the frequency of the uniform alternating axially symmetric magnetic field of the initial applied voltage is reduced by oi times compared to the registered value, and the corresponding frequency of the uniform alternating axially symmetric field is recorded, and the initial the magnetic permeability and electrical conductivity of the controlled product is determined from the ratios

relative voltage applied, the value of which is recorded, and then vm {decrease the frequency until the moment 30 when the component is

Max Wade See) Mr. MaKcFeTJ | 5 N7T

pjUoWzR

where IU and (J are, respectively, the initial magnetic permeability and specific electrical

the conductivity of the controlled product; idts (M) - relative contributed

voltage;

N is a generalized parameter; Nj, is the value of the generalized parameter corresponding to the frequency Q of the homogeneous variable axis {electric magnetic field, at which it is valid

914A8260

the component of the applied voltage has decreased compared to the registered value by a factor of oL ("i is a constant);

J / wJfA

9FF

O 0.1 02 0.5 Phases. 2

ten

coefficient; filling agent; radius controlled

products;

magnetic constant; effective magnetic

cylinder permeability.

Claims (1)

Claim The method for determining the electrically accurate value of the real component U _8H . For this, the value of the value from BVC 9 is compared in BS 11 with the value contained in BVX 10. BS 11 generates a write signal of the real component 0 _VVC in BVC 10 only if the value stored in BVC 9 is greater than in BVC 10. The search cycle occurs in the frequency range providing a clear maximum capture. To do this, use the circuit formed by blocks 9 and 10, the switch 12 and the second comparison unit 14. The frequency of the generator 15 6 increases until there is a signal at the first output of BS 14, indicating that the signal at the output of BVX 9 has not become less than or equal to 0.8 of the maximum value 20 recorded in BVX 10, which is received on BS 14 through KOM 12. When performing this condition, first, the voltage on the CVS 10 proportional to the maximum BeU _gH, postu- paet 25 on the block 15, and secondly, the switch 12 connects to the input of the BS 14 D output 13 and, consequently, half value maksYe ^m _6N enters at the input of the EC 14, thirdly, BS 14 transfers the VCO 6 to the mode of decreasing the excitation frequency and, fourthly, block 15 calculates the value of the magnetic permeability p from relation (4). After that, BS 14 compares the real 'component Й _{in (1} from the output of BVX 9 and half its maximum value. At the time of equality of these values, BS 14 generates a prohibition signal for changing the ₄ θ VCO frequency 6. Based on this signal from the output of the Converter 16 to the block 15 comes the voltage equivalent to the frequency of the excitation current. This signal is through the gap ₄₅ determined fissile conversion time frequency voltage FNR 16, via the delay line 17 is supplied to control input unit 15, allowing calculation of the specific value the electric conductivity gg Coy b of relation (8). In this case, block 15 can be made in the form of an analog or digital processor (in the latter case, the corresponding ADCs are installed on its analog inputs) operating according to the described algorithm. The proposed method eliminated a number of methodological errors, general and magnetic parameters of cylindrical products, including the sequential exposure of a sample to a homogeneous variable axisymmetric magnetic field of two different frequencies, registration of the relative introduced voltage at both frequencies, about τη and the second s. I mean that, in order to increase the accuracy of the method, in the process of registering the relative introduced voltage, its actual component is isolated, while the frequency of the homogeneous variable axisymmetric magnetic field is first changed until the maximum of the real component of the relative applied voltage, the value of which is recorded, and then the frequency is reduced until the actual component of the relative applied voltage decreases compared with the recorded value οί time, and record the corresponding frequency axisymmetric uniform alternating field, and initial permeability and electrical conductivity controlled article is determined from the relations maksBei _8n (k2__ I maxBeT ’σ = -Lywhere ρ and (j - respectively, the initial magnetic permeability 'and the electrical conductivity of the controlled product; - relative insertion voltage; N is a generalized parameter; Nj, is the value of the generalized parameter corresponding to the frequency d) _{2 of a} uniform variable axisymmetric magnetic field at which the real 9 1448260 10 the component of the relative applied voltage decreased in comparison with £ - · duty cycle; R is the radius of the controlled product; с with the registered value in ° C times (βύ constant); magnetic constant; effective magnetic permeability of the cylinder. FIG. 2 Compiled by S. Shumilishskaya Editor M. Kelemesh Tehred L. Serdyukova Proofreader V. Girnyak Order 6841/49 Circulation 847 Subscription VNIIIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and printing company, Uzhhorod, st. Project, 4