SU531074A1 - Flaw detector for controlling hollow ferromagnetic products - Google Patents

Description

one

The invention relates to non-destructive quality control of hollow ferromagnetic products by physical methods and can be used to control the quality of pipes.

A flaw detector with a eddy current modulation measurement channel is known for monitoring the quality of ferromagnetic tubes Cl.

Its disadvantage is the ability to detect only defects that come to the surface and are close to the surface (for example, discontinuities).

An induction flaw detector is also known, which can detect defects using a magnetic measuring channel, located at different depths in the wall of pipe 2. The disadvantage of this flaw detector is its lower sensitivity to defects on the inner surface, compared with similar defects on the outer surface of the pipe, and the lack of effective separation of signals from defects in the outer and inner surfaces, for example, with a view to improving sensitivity.

The closest to the invention in terms of its technical nature is a flaw detector for monitoring hollow ferromagnetic pipes containing eddy current and magnetic measuring channels / connected to an inductive sensor with a generator. Measurement channel outputs are connected to their own defect indicator 3. external surfaces of pipes, which is associated with autonomous operation of measuring channels.

The aim of the invention is to increase the reliability of detection of defects in the inner and outer surfaces of the product.

Claims (3)

This is achieved in that the measurement magnetic channel is provided with an inverter node and an algebraic addition node with two inputs, which are connected in series and connected between the magnetic channel output and a defect indicator, and the eddy current channel is equipped with an algebraic addition node with two inputs connected between the eddy current output and the indicator defects, the output of the eddy current channel is connected to the second input of the algebraic addition node of the magnetic channel, and the output of the magnetic channel is connected to the second input of the node al ebraic addition of the eddy current channel. Fig, 1 shows a block diagram of the proposed flaw detector; in fig. 2 - time diagrams of the flaw detector operation. The flaw detector contains an induction sensor 1 connected to the output of a high-frequency generator, and a magnetic measuring channel 3 and an eddy current measuring channel 4 are connected to the output of sensor 1. The outputs of channels 3 and 4 are connected to node 5 of the algebraic sum of signals, which has two inputs. The inputs of channels 3 and 4 are connected to these inputs. The node 6 of the algebraic addition of signals also has two inputs that are connected to the output of channel 4 directly, and to the output of channel 3 through the node 7 of the inverter. The outputs of nodes 6 and 5 are connected with their indicator 8 and 9 defects, respectively. FIG. 2 shows the time diagrams of the flaw detector operation; a) - signals of defects at the exit of the eddy current channel 4 b) - signal of defects at the output of the magnetic channel 3; 8) - signals of defects n output of the inverter node 7, 2.) - signal at the output of the uach 5 algebraic addition signals, E) - signal at the output of the node 6 algebraic addition signals. 1 - signal of an external defect; II - signal of an internal defect. The flaw detector works as follows. A hollow article, such as a pipe to be inspected, is placed in the control zone in a constant magnetic field. As the induction sensor 1 rotates around the pipe, the high-frequency supply voltage of the generator 2 is modulated. The modulated voltage is fed to the input of the eddy current channel 4 with an amplitude-phase separation of the signal. The bandwidth of channel 4 is + 10 of the carrier frequency of generator 2 (Fig. 2). At the same time, when rotating around a pipe placed in a constant magnetic field, sensor 1 counts the dissipation magnetic fields excited by discontinuities of the metal of the pipe being monitored. The induced emf is proportional to the magnitude of the scattered magnetic fields, released in magnetic channel 3 (Fig. 2.6). The signals from the output of channels 3 and 4 are connected to the inputs of nodes 5, 6, and to the input of node 6 The signal from the output of the magnetic channel 3 is fed through inverter 7. Signals from the outside when the amplitude-phase method of separating signals from the magnetized wave is different polarity, and this allows to receive in algebraic addition node 5 the sum of the output signals from the external defects of channels 3 and 4 and the equality of the output signals from internal defects of channels 3 and 4 ( Fig. 2, d). Thus, it is possible to isolate signals from external defects and suppress signals from internal defects generated at the outputs of both channels (eddy current and magnetic). Similarly, in node 6 of algebraic addition, signals from internal defects are extracted and suppressed from external ones by introducing an inverter node 7 (FIG. 2). From the output of node 5, the signal goes to the indicator 9 for registering external defects, and from the output of node 6 to indicator 8 registration of internal defects. At the same time, the amplitude discrimination levels of the indicators 8 and 9 of defects are set with different amplitude thresholds and brightness, which ensures reliable detection and separation of external and internal defects, i.e. allows to increase the reliability of detecting defects of the inner and outer surfaces of the product. An inventive defectoscope for monitoring hollow ferromagnetic products, comprising a generator, a sensor connected to it, eddy current and magnetic measurement channels each with an output defect indicator connected to the output of the sensor, and in order to improve the reliability of the detection of internal defects and the outer surfaces of the product, the magnetic measuring channel is equipped with an inverter node and an algebraic addition node with two inputs, which are connected in series and connected between the output of the magnetic channel a and an indicator of defects, and the eddy current channel is equipped with an algebraic addition node with two inputs connected between the eddy current output and a defect indicator, the eddy current output is connected to the second input of the algebraic addition channel of the magnetic channel, and the output of the magnetic channel is connected to the second input of the node algebraic addition of a V-channel channel. Sources of information taken into account in the examination: 1. USSR author's certificate 5 Cl. G- 01 N 27/86 No. 191196 dated 06.26.65 2. USSR author's certificate j С O1 N 27/86 No. 216350 of 02.21.67. 3. US patent number 3743928 class, 324-37 from 1O.09.68,