SU504967A1 - Automatic fluxgate coercimeter - Google Patents

Description

the same value of the measured magnetic characteristic (demagnetization current) with repeated control operations on the same part of the product without its preliminary demagnetization.

The drawing shows a block diagram of the proposed automatic fluxgate coercimeter ... The blocks and nodes of the device are connected as follows.

The output of power supply 1 is connected to switch 2. Switch 2 has four outputs, two of which are connected to unit 3 magnetizing the product in positive polarity and to unit 4 demagnetizing the product from positive polarity. The two other outputs switch 2 is connected to the unit 5 magnetizing the product in negative polarity and to the unit 6 demagnetizing the product from negative polarity. The outputs of the magnetizing units 3 and 5 are connected to the magnetizing windings 7 of the attachment electromagnet 8. Block 4 includes Schmidt trigger 9, whose input is connected to the indicator winding 10 of the fluxgate of the attachment electromagnet 8, pulse generator 11, cascade 12 coincidence, normalizer 13 and craze unit 14. memory with demagnetization current controller. Unit 6 includes a Schmidt trigger 15 connected to the indicator winding 10 of the fluxgate of the attachment electromagnet 8, a pulse generator 16, a matching stage 17, a normalizer 18, and a short-term memory unit 19 with a demagnetization current controller. Blocks 4 and 6 of the positive and negative magnetization of the product section are connected to the windings 20 of demagnetization of the attachment electromagnet 8 with their two outputs, and to the summing of the separating device 21 to the other two outputs. The output of the summing-dividing device is connected to the indicator 22.

The control of products with an automatic fluxgate coercimeter is performed as follows.

Attached electromagnet 8 is installed on the monitored part of the product, and then switch 2 is started. At the initial moment of the measurement cycle, commutator 2 connects power source 1 via unit 3 to magnetizing winding 7 of attachable electromagnet 8. As a result of current pulse passing through winding 7 of magnetizing attachable electromagnet 8, the product acquires a positive magnetization. Upon completion of the magnetization process, the switch 2 connects the power source 1 through the block 4 to the winding 20 demagnetization of the attachment electromagnet 8.

The process of increasing the demagnetization current in the winding 20 until the compensation of the residual field of the magnetized area of the product proceeds as follows.

Schmidt trigger 9 converts the alternating voltage of the indicator winding 10 of the fluxgate into square impulses arriving at one of the inputs of the cascade 12 coincidence. To the other input of the cascade 12 of coincidence, U-shaped pulses are received from the driver AND strobe pulses. At the output of cascade 12

the coincidence of the signal can be distinguished only if the pulses coming from the driver 11 and the Schmidt trigger 9 coincide in time. If there are pulses at the output of the coincidence stage 12, the normalizer 13 is started, from the output of which the pulses calibrated in duration and amplitude go to the short-term memory unit 14 with the demagnetization current controller.

As the pulses from the output of the normalizer 13 to the input of block 14, from the output of the latter, demagnetization current enters the winding 20, the value of which increases with the number of incoming pulses. The process of increasing the demagnetization current lasts until the residual field is compensated for the positively magnetized area of the product by the field of the attachment electromagnet 8 created by the demagnetization current flowing through the winding 20. At the time of compensation, the voltage at the output of the indicator winding 10 of the ferronde will disappear, trigger 9 9th trigger will disappear, trigger 9 9th trigger will disappear, and the 9 9 trigger will disappear, the trigger 9 9 will disappear. deliver pulses to coincidence stage 12, and the normalizer 13 will stop. The process of increasing the demagnetization current will stop. The presence of a matching stage is necessary to eliminate the effect of non-compensating residual field.

section of the product. Indeed, in case of a random fluctuation of the demagnetization current to a value exceeding the compensation field, the phase of the voltage in the winding 10 of the fluxgate varies by 180 e. degrees, and the pulses from trigger output 9 will not pass through cascade 12 coincidence.

Thus, in the coercimeter circuit, a mode is established in which the field created by is. current demagnetization compensates

residual field positively magnetized area of the product. The absolute value of this current is stored in the summing-dividing device 21. This completes one measurement cycle.

At the next time point, the switch 2 connects the power source 1 through the block 5 to the magnetizing winding 7 of the attachment electromagnet 8. As a result of the magnetization of the controlled section of the product by the field, the polarity of which is opposite to the polarity of the previous magnetization field, the latter becomes negative magnetization. At the end of the magnetization process, switch 2 connects source 1

power through the block 6 to the demagnetization winding 20 of the electromagnet 8. The process of compensating the residual field of the plot when it is negatively magnetized proceeds similarly to the process of compensation of positive magnetization described above. The demagnetization current from the output of the block 19 enters the winding 20 of demagnetization of the attachment electromagnet 8. The absolute value of this current is stored in the summing-dividing device 21.

At the next time point, switch 2 again switches power supply 1 to measure the demagnetization current corresponding to the positive magnetization of the product section, etc. The magnitudes of the demagnetization currents corresponding to the positive and negative values of the magnetization of the controlled section of the product enter the analog-type summing device 21 , the output of which is connected to the indicator 22, which shows the value of the demagnetization current, averaged over a variety of measurements, the value that is EEC measure coercive force portion of the article.

The device operates in a quasistatic mode, when the eddy currents do not yet affect the shape of the hysteresis loop of the material of the monitored part of the product, which is important for improving the accuracy of measuring the static coercive force. The number of cycles of magnetization reversal is chosen experimentally.

Compared with the known devices, the proposed coercimeter provides an increase in the accuracy of the control of the magnetic characteristic (demagnetization current) due to the possibility of repeated measurement on the same area of the product without its preliminary demagnetization in a variable field of decreasing amplitude, due to the magnetic preparation of the material of the product during cyclic magnetization reversal of the area , as well as due to the exclusion of a random error when averaging the measured value of the demagnetization current, which is ensured by introducing device units 5 and 6, and the summing-divider.

Claims (1)

Invention Formula An automatic fluxgate coercimeter for magnetic control of products, containing a series circuit from a power source, a magnetization unit of the product into a positive polarity, added an electromagnet, a degaussing unit of a positive polarity, connected by an additional input to a switchboard, and an indicator, characterized in that, in order to increase the accuracy of control, it is equipped with a magnetization unit of the product into negative polarity and a degaussing unit of the product of negative polarity, connected in series through the added electromagnet and connected between the switch and the indicator, and the summing-dividing device connected between the outputs of the demagnetization units and the indicator ator, and the degaussing unit of the product of negative polarity connected by an additional input to the switch.