SU544904A1 - Device for finding cracks in ferromagnetic material - Google Patents

Description

one

The invention relates to non-destructive testing methods and is intended to locate cracks, in particular in steel tapes. It can be used in ferrous metallurgy in the control of sheet steel, in the control of rails, etc.

A magnetic flaw detector is known to control railways, in which two magnetic systems are used to separate the signals from the defect and interference. The disadvantage of such a flaw detector is the difficulty of constructing a circuit and processing the obtained results, which leads to a decrease in the measurement accuracy.

A device for locating cracks in railway rails is known, which comprises an electromagnet, an indicator roller, an amplifier connected to an indicator roller, and a display unit.

Such a device is close to the invention in its technical essence and the achieved result; however, it does not provide sufficient accuracy in measurement.

The aim of the invention is to improve the measurement accuracy.

This is achieved by the fact that the device is supplied with two measuring channels connected to the output of the amplifier, containing in series two waiting multivibrators and a matching circuit, the second

the input of which is connected to the output of the amplifier and the OR circuit connected between the outputs of the two measurement channels and the display unit.

FIG. 1 is a block diagram of the device; in fig. 2a and 26 show the location of the indicator roller to the left and to the right, respectively, of the crack in the product; in fig. Figure 3 shows the stress diagram of the block diagram.

The device contains an electromagnet 1 fed from an alternating current source, a 1I1-switch coil 2 located on a ferromagnetic core and an epithelically longitudinal axis of the product under test, such as steel tape (not shown), a limiting amplifier 3 (amplifier) with a paraphase output, two identical channels each of which consists of two pending multivibrators 4 and 5 or 6 and 7 and

circuits 8 or 9 matches, OR circuit 10 and output block 11, for example in the form of a counter. The device has the following constructive structure: the coil 2 is connected to the input of the amplifier 3, the outputs of which are connected to the inputs of the circuits 8 or 9 coincidence. In this case, the output is connected directly to the first input of the matching circuit 8 and through the pending multivibrators 4 and 5 to the second input, and the other output of the amplifier 3 is connected and connected to the inputs of the 9 analog circuit: to the first input directly, and to the multivibrators of the second input and 7. The outputs of circuits 8 and 9 match via circuit 10 AND / 1I are connected to the output unit 11.

The device works as follows.

The power supply voltage is indicated in indicator 1 satin 2 iair / kenne sinusoidal. When the coil 2 defects in the tape (Fn. 2a and 26) are detected, the iargy phase changes. This voltage is converted into signals of a rectangular shape by amplifier-limiter 3 and is then fed to start-up multivibrators 4, 5 or 6, 7. Pending multivibrators 4 and 6 produce low short-circuits that delay the launch of multivibrators 5 and 7 .-.....

When the phase of the signal at the output of the plug 2 is changed, the output signal 12 is negatively polarized (Fig. 3). The output of the standby L1 multivibrator 5 and the output of the limiting amplifier 3 coincide in phase. At the output of the scheme 8 Sovnadeii on Vits stsnal. This signal through the scheme 10 LII nroydet pa counters 11.

Let the cracks in the controlled isdeln (steel tape), the dvn of her dvnzhenpn is from the coil 2 (fng. 2a). In this case, the magnetic note created by the electromagnet 1, closes through the tent, is indicated by a crack and in the coil 2 is induced by an E.D.S. After the new cracks of the cat 2 (the crack is to the left of the use of the rolls - fig. 26), the magnet note in the small reel will change its shape and induce (phpg 3) in it E.D.S. anti-phase phase, i.e., the signal of a defect is not converted into a change in the phase of the viral radiation. The change of the phase of the irregular signal and the irn occurs at any speed irrelevant to the tape.

The signal 12 from the output of the coil 2 and after amplification by the amplifier-limiter 3 converts into square pulses 13. These emulsions are differentiated and fill the front of the front with multivibrators 4 and 5, whose impulses are given on

14 n 15, positions. The signal 16 at the output of the circuit 8 will be connected only by the same 13n15 signal from the output of the amplifier of the chaser 3 and the waiting multivibrator 5 when the phase is changed.

If the signal of the defect and, consequently, the change of the voltage phase at the output of coil 2 but leads to negative semi-volatility, then the signals of phase change from the second channel of the phase detection will come: from the other output of the limiting amplifier 3 n from the same center waiting for the cartoon 1 vibrator 6 7. The signal from the output of circuit 9 coincidence through circuit 10 OR to the counter AND the number of cracks.

Claims (2)

1. Auth. ev No. 171639, cl. G OLN 27/86, 1964. 2. “Rail flaw detection. All-Union Publishing and Polygraphic Association of Ministry of Railways, Moscow, 1963, pp. 130-131 (prototype). - M -