SU1226260A1 - Arrangement for measuring coercive force of ferromagnetic materials - Google Patents

Abstract

The invention relates to instrumentation technology, is intended for the local measurement of the coercive force of products made of sheet ferromagnetic material, for example, when checking masks of color kinescopes and can be used in electrovacuum and other industries. The purpose of the invention is to increase the accuracy and speed of measurements, achieved by introducing into the device of a differentiating element 7, a U-shaped core 5 made of a magnet of a soft material and a pulse former 8. The device contains a generator of magnetizing current 1, magnetizing 2. and measuring 4 windings, test article 6, strobe pulse generator 9, key circuit 10, peak detector 11, recording device 12. Shaper 8 contains a comparator 13, trigger 14, rectifier 15, limiter 16 and threshold detector 17. Operation of the device This is shown in the time diagrams provided in the specification. 2 Il. i (L to GS 05 to Oi

Description

The invention relates to measuring technique and is intended for. local measurement of the coercive term of products made from ferromagnetic sheet material, for example, when monitoring picture tube masks, and can be used in electrovacuum, metallurgical and other branches of the national economy.

The purpose of the invention is to improve the accuracy and speed of measurements.

FIG. 1 shows a functional diagram of the device; in fig. 2 - voltage plots that describe the operation of the device.

The device contains a magnetizing current generator 1, the output of which is connected to a series-connected magnetizing winding 2 and a resistor 3, a measuring winding 4, a U-shaped ferromagnetic core 5 with magnetizing and measuring sockets applied to it, which differentiates element 7, the input of which is connected to the measuring winding, pulse shaper 8, one input of which is connected to the output of differentiating element 1, the other to the cut The gateway 3, a gating pulse generator 9, the input of which is connected to the output of the pulse former, CL} is the reference circuit 10, the signal input of which is connected to the resistor 3, and the control input to the output of the generator 9 of gating pulses connected in series 12. The input of the peak detector 11 is connected to the output of the key circuit 10.

The pulse shaper 8 contains a comparator 13, trigger 14 and serially connected rectifier 15 limiter 16 and threshold detector 17. The input of the receiver 15 is connected to the output of the differentiating element 7 and the output of the threshold detector 17 is connected to the trigger input 14. The input of the commator 13 is connected to a resistor 3, and the output - with the counting input of the trigger 14, the output of which is connected to the generator input 9 gating pulses-.

. The device works as follows.

U-shaped ferromagnetic core 5 with magnetized on it

five

0 5

five

0

five

0

five

0

2 and measuring 4 windings are pressed by the poles to the monitored product 6.- At this, the section of the monitored product 6, which is located between the poles of the U-shaped ferromagnetic core 5, is periodically re-magnetized by means of a magnetizing current generator 1 along a limiting hysteresis loop.

The output voltage of the measuring winding 4 has (due to the nonlinear dependence of induction in ferromagnetic materials on the intensity of the external magnetizing field) a clearly higher surge (Fig. 2c), the minimum of which determines the moment when the generator current 1 reaches the value at which product 6, the magnetic field strength is equal to its coercive force.

From the output of the measuring winding 4, the voltage goes to the differentiating element 7, at the output of which at the moment of passing the said surge, negative and positive voltage pulses appear (Fig. 2d), and the leading edge of the positive pulse corresponds to the positive: sho minimum of this surge . The pulse shaper 8 forms, ao, the leading edge of this pulse, a positive voltage drop (Fig. 2g), which starts the gating pulse generator 9, producing a short voltage pulse (Fig. 23) arriving at the control input of the key circuit 10.

During the operating time of the control 1P 1puls, the key circuit 10 connects the peak detector 11 to the resistor 3, as a result of which the output of the detector M is set to a voltage equal to the voltage on the resistor 3 at the time of the strobing pulse. The magnitude of this voltage, proportional to the coercive force of the test article 6, is measured by means of a recording device 12.

The pulse former is returned to its initial position (low voltage level at the output) at the moment of zero crossing from low nage level to high at resistor 3 (Figs. 2a, 2g).

The shaper 8 pulses works as follows.

When the generator 1 current changes from negative to positive when the voltage across the resistor 3 passes through zero (Fig. 2a), the output voltage of the comparator 13 changes from low to high (Fig. 2b). This voltage drop is applied to the counting input of the trigger 14, as a result of which a low voltage level is established at the trigger output (Fig. 2g). Positive and negative voltage pulses (Fig. 2d) from the output of differentiating element 7 are fed to rectifier 15, positive pulses (Fig. 2d) from the output of which are limited in amplitude in limiter 16, and then fed to the input of threshold detector 17. Eg pulses (Fig. 2e) from the output of the threshold detector arrive at the installation input of the trigger 14, with the result that a high voltage level is established at the output of the trigger (Fig. 2g). A positive voltage drop at the output of flip-flop 1 triggers a strobe pulse generator 9.

Other voltage pulses (Fig. 2e) arising at the output of the threshold detector 17 arrive at the installation input of the trigger 14 after the passage of a pulse, which characterizes the minimum voltage of the measuring winding 4, and therefore does not change

trigger state 14.

Claims (1)

Invention Formula Device for measuring the coerciti force of sheet ferromagnetic materials 15 226260 Materials containing a magnetizing and measuring windings, a magnetizing current generator, the output of which is connected to a series-connected uni- form magnetizing winding and a resistor, a gating pulse generator, a key circuit whose control input is connected to the output of the gating pulse generator, 0 peak detector, input which is connected to the output of the key circuit and the registering device connected to the output of the peak detector, is required because, in order to improve the accuracy and speed of measurements, It is equipped with a differentiating element, a U-shaped ferromagnetic core made of a magnet of a material and a pulse impulse forger, which is made of a comparator, a trigger, a rectifier, a limiter and a threshold detector, and the rectifier, the limiter and the threshold detector are connected in series , the rectifier input is connected to the output of the differentiating element, the output of the threshold detector is connected to the setup input of the trigger, the input of the comparator is connected to a resistor, the output of the comparator is connected to the counting input t the trigger, the trigger output is connected to the input of the gating pulse generator, the input of the differentiating element is connected to the measuring winding, and the magnetizing and out of thirty 35 Measuring windings are placed on a U shaped ferromagnetic core of magnet of a soft material.