RU47104U1 - MAGNETIC DEFECTOSCOPE - Google Patents

Abstract

Number of title of protection ........................

Type of title of protection ..........................

Country of publication Russian Federation MKI Index G 01 N 27/84 Registration number of the application .....................

Application date...............................

Date of publication ..................................

Surname, name, patronymic of the authors Gruzdev Alexander Anatolyevich,

Lozovsky Vladislav Nikolaevich, Shelikhov Gennady Stepanovich

Applicant ZAO Diagnostic Scientific and Technical Center

Defectoscopy

The name of the utility model ... Magnetic flaw detector

Priority Data

1. The utility model relates to the field of non-destructive testing of parts and assemblies of aircraft, automobile, railway and other equipment by the magnetic particle method. 2. The utility model allows to reduce the weight and overall dimensions, improve the operational characteristics of the flaw detector, which allows magnetizing and demagnetizing the tested parts by a pulse current field. 3. The goal is achieved by the fact that the basis of the flaw detector is a pulse magnetization circuit with discharge capacitors without a pulse transformer. Pulse capacitors are discharged through the thyristor bridge directly to the part under test or to a magnetizing device (solenoid or cable).

Description

The utility model relates to magnetic particle inspection and can be used to detect defects such as discontinuity of material in ferromagnetic products of aviation, automobile, railway and other types of equipment when magnetized by a pulse current field.

Known devices for the magnetization of products based on various principles.

In the flaw detector 77PMD-3M (see Appendix 1), a current pulse in a flexible cable folded in the form of a solenoid is obtained by short-circuiting the cable to the terminals of a high power supply. The maximum amplitude of the current pulse in the cable with a cross section of 10 mm sq. reaches 700 A. In this case, the power source (battery, generator voltage = 24 V) operates in the short circuit mode. This is a significant drawback of such devices. In addition, the mass of such a device with a power source is more than 100 kg.

Known magnetizing device UNM 300/2000, which uses a circuit with discharge capacitors that discharge to the primary winding of a pulse transformer. In the secondary winding of this transformer, connected to a magnetizing cable, a current pulse with an amplitude of up to 2000 A occurs. The disadvantage of the UNM 300/2000 device is its large mass from 45 to 70 kg (see Appendix 2). This device turned out to be unsuitable for magnetic particle inspection of nodes located at a height, such as wing attachment nodes, aircraft tail units, helicopter propeller blades due to its large mass.

The closest technical solution to the claimed utility model is the pulse unit of the PMD-70 flaw detector weighing 20 kg, developed using copyright certificate No. 227668 (see Appendix 3). The pulse block is based on a circuit with discharge capacitors and a pulse transformer. Using a unit weighing 20 kg to control parts located at a height of several meters (aircraft, lifting mechanisms, etc.) is also difficult. The increase in mass occurs due to the pulsed

transformer. In the PMD-70 flaw detector, the measurement and regulation of the amplitude of the pulse current is not provided.

The objective of the proposed utility model is to reduce the mass and dimensions of the flaw detector by at least 2 ... 2.5 times, which can be achieved by developing a circuit that does not contain a pulse transformer, which is the main factor in increasing the mass of a pulse flaw detector. A flaw detector weighing 7 ... 8 kg, which allows to obtain a pulsed current of up to 2500 A, will allow efficient magnetic particle inspection of parts of a wide range of parts, including those located at a height. The decrease in the mass of the flaw detector is also associated with a decrease in its overall dimensions, an improvement in operational characteristics and an increase in the performance of inspection.

Figure 1 shows the structural electrical diagram of the proposed magnetic flaw detector, which is indicated: 1 - power supply; 2 - voltage converter; 3 - current measurement circuit; 4 - current sensor (Hall); 5 - contact current key; 6 - current switch; 7 - current regulator; 8 is a control diagram; 9 - a comparator; 10 - operating mode switch: 11 - “Start” button; 12 is a circuit for resetting the readings of the measurement circuit; C ₁ ... C _n - discharge capacitors; T1-T4 - thyristors of a thyristor bridge; R1, R2 - resistors of the voltage sensor (negative feedback sensor); 13, 14 - contacts at the input of the comparator; 15 is a software device in a control circuit; 16 - magnetizing devices (cable, solenoid, electrical contacts).

The essence of the proposed utility model is as follows. The proposed utility model is based on the use of a circuit with discharge capacitors, the discharge of which is carried out through a thyristor bridge to a magnetizing device or to a tested part. The circuit does not contain a pulse transformer. The stability of the control characteristics and the stability of current pulses is ensured by the presence of negative feedback. The flaw detector mass reduction is ensured by the fact that the flaw detector circuit does not contain a pulse transformer. With a flaw detector mass of 20 kg, two flaw detectors carry out inspection, and with a flaw detector mass of 7 ... 8 kg, one inspector carries out inspection, which increases labor productivity. In addition, with a smaller mass of the flaw detector, better working conditions are created, which also increases the productivity of the inspector. The proposed flaw detector contains (figure 1):

- a power supply 1 connected through contacts 5 of the current switch 6 to a voltage converter 2. The power supply is powered from an alternating current network of 220 V or from a direct current network of 24 V. This voltage is accepted in all types of aviation.

- voltage converter 2, the output of which is connected to discharge capacitors C ₁ ... C _n and thyristor bridge T1 ... T4;

- voltage sensor R1, R2 (negative feedback sensor) connected to the output of the voltage Converter and the first (a) input of the comparator 9;

- current regulator 7, associated with the second (b) input of the comparator 9;

- control circuit 8, which forms the operating modes, controls the thyristor bridge, generates a “Reset” signal and supplies it to the measurement circuit, generates control signals for the current switch 6;

- a comparator 9 having a first input (a), a second input (b) and output (c);

- current measurement circuit 3 and current sensor (Hall) 4;

- discharge thyristors T1 ... T4, through which there is a discharge of discharge capacitors to magnetizing devices (cable, solenoid or to the tested object) 16;

- a switching device 13, 14, connecting to the second input of the comparator either a current regulator 7 or a software device 15;

- the software device 15 of the control circuit 8 provides signals to the second input of the comparator 9 in accordance with the established operating modes: single pulses, continuously following current pulses, bipolar current pulses decreasing in amplitude to zero (during demagnetization);

- magnetizing devices 16;

- “Start” button 11, which includes the modes set by the “Operating modes” switch.

- a magnetic indicator for detecting defects after magnetization.

The operation of the flaw detector circuit is as follows.

A. In the mode of magnetization by a field of single current pulses,

In the initial initial state: the voltage at the output of the voltage converter 2 is zero, the capacitors C ₁ ... C _{n are} discharged, the voltage at the feedback sensor R1 and R2 is zero.

When the mode switch is set to the position of single pulses “IMP”, the voltage from the current regulator 7 is supplied to the second input (b) of the comparator 9, the voltage from the output (c) of the comparator is supplied to the current switch, which trips and closes contact 5. The voltage from the power supply is supplied input to the voltage converter 2. The voltage on the converter output will begin to increase, and the capacitors C ₁ ... C _n will be charged accordingly will increase the voltage on the sensor R1, R2 and the first (a) input of the comparator 9. When reaching equalities voltages on first and second comparator inputs an output signal at the output of the comparator becomes zero. The current switch trips, pin 5 opens. The voltage at the inverter output will not increase. Capacitors C ₁ ... C _n remain charged up to this voltage. When the “Start” button is pressed from the control circuit, the triggering pulses are applied to the control electrodes of thyristors T1 and T4, and thyristors T1 and T4 open. The discharge of capacitors C ₁ ... C _n to the cable (solenoid) of the magnetizing device occurs.

Subsequently, the charge of the capacitors C ₁ ... C _{n is} repeated. When the "Start" button is pressed, the capacitors discharge to the magnetizing device again.

When the position of the current regulator slider is changed, the capacitors will be charged to a lower or higher voltage; accordingly, the current amplitude in the magnetizing device will change.

B. In the mode of continuously following current pulses of the applied field.

In the control circuit 8, pulses are generated that open the thyristors T2 and T4 with a frequency of 0.5 ... 1 Hz. With the same frequency, discharge capacitors C ₁ ... Cn are charged and discharged through thyristors T1 and T4 to magnetizing devices. During the action of field pulses, a magnetic indicator (magnetic suspension or dry magnetic powder) is applied to the magnetizing device (cable, solenoid or test item) conduct magnetic particle control in the applied magnetic field continuously following current pulses.

B. When demagnetizing tested parts

When the mode switch is set to the “Demagnetization” position, the second output of the comparator is connected to terminal 14, through which a smoothly decreasing voltage from the maximum value to zero is supplied from the software device 15. The maximum value of this voltage corresponds to the maximum value of the voltage at the output of the voltage converter 2. At the same time, control pulses are generated in the control circuit, which, in accordance with the program, the thyristors T2, T4 and T1, T3 are opened alternately with a frequency of 0.5 ... 1 Hz. When thyristors T1 and T4 are opened, a current pulse of positive direction will pass in the magnetizing device, and when thyristors T1 and T3 are opened, they will flow in the opposite direction. As a result, bipolar current pulses, decreasing in amplitude from the maximum value to zero, will pass in the magnetizing device. The optimal duration of this demagnetization process, established experimentally, is 50 ... 60 s.

Current measurement is carried out by a measuring circuit. A Hall sensor was used as a current sensor. The flaw detector is designed to be powered from a 220 V, 50 Hz network or from a DC 24 ... 27 V network. A magnetic indicator is applied after magnetization.

An example of the proposed flaw detector. The current layout of the proposed flaw detector was made according to the proposed scheme. In which the elements were used:

- discharge capacitors with a capacity of 70,000 μF;

- discharge thyristors;

- microcontroller P1C6F84;

- Hall sensor type KSY 14.

The manufactured layout of the proposed flaw detector has the following technical characteristics:

- weight 7.5 kg;

- maximum current 2500 A;

- demagnetization time 50 s;

- operating modes: single current pulses; continuously following current pulses; bipolar current pulses with decreasing amplitude (demagnetization mode);

- The circuit is mounted in a Case-type suitcase.

Thus, the conducted and justified set of features is necessary and sufficient to obtain a positive effect, reducing the mass and overall dimensions of the flaw detector, increasing labor productivity and operational characteristics of the flaw detector.

Claims (1)

A magnetic flaw detector comprising a power supply unit, a voltage converter, discharge capacitors, magnetizing devices, characterized in that the power supply unit is connected via a current switch to a voltage converter, the output of which is connected to discharge capacitors connected to the magnetizing devices through a thyristor bridge, the control electrodes of which are connected to control circuit, and plus its diagonal of power supply through a voltage sensor connected to the first input of the comparator, the second input of which is connected to the regulator ohm of current, and its output is with a current switch.