SU687426A1 - Device for testing permanent magnets - Google Patents

Description

one

The invention relates to magnetic measuring instruments and can be used for the technical control of permanent magnets intended for driving electric machines.

Known devices containing an electromagnet, a generator, and a match

The lack of known devices is low reliability.

The closest in technical essence to the present invention is a device comprising an electromagnet, an executive-indicator unit, a master oscillator, a software unit, an amplifier, a magnetic flux sensor, a key, four elements of coincidence, and a null indicator 2.

A disadvantage of the known device is low reliability.

The purpose of the invention is to increase the reliability of the control.

This goal is achieved by the fact that a device containing an electromagnet, an executive-indicator unit, a master oscillator and a software unit connected in series, as well as an amplifier and a magnetic flux sensor connected to its input, a key, four elements of a matching null indicator, are additionally entered an analog-to-digital converter, a reversible counter, a serially connected memory unit and a comparison unit, the input of which is connected to the amplifier output, the key input and the analog-digital converter input, to its the course associated with the first inputs of the first and second elements of the match, the outputs of the latter are connected to the first and second inputs of the reversible counter, the first output of which is connected to the input of the null indicator, and the second output of the reversible counter is connected to the input of the program block, the first and third outputs of which are connected with the second input of the first match element, the second input of the second and the first input of the third coincident element, as well as with the first input of the fourth match element, respectively, the second input-one quarter The first coincidence element is connected to the output of the null iner, and the output of the fourth element of the coincidence is connected to the first input of the executive-indicator unit, the second input connected to the output of the third coincidence element, the second input of which is connected to the output of the comparison bloon, while the input of the unit is connected with the release of the key. FIG. 1 shows the structural scheme of the proposed device; Fig, 2 timing charts illustrating the operation of this device. The device contains magnetoprovod. demagnetization coils 2, magnet 3 under test, non-magnetic spacers 4, magnetization coils 5, magnetic flux sensor 6, start generator 7, program block 8, amplifier 9, converter 10, key 11, comparison block 12, memory block 13, elements 14 through 17, a reversible counter 18, a null indicator 19, and an actuator indicator 20. The device operates as follows. Before the start of control of a batch of magnets of a certain size, a strip of non-magnetic material of such thickness is applied to the poles of an electromagnet so that the state of the tested magnets placed in the electromagnet is equivalent to their condition assembled with the product. Then, a standard magnet is placed in the magnetic system gap, which is magnetized to a state of technical saturation and then subjected to the action of: a demagnetizing field with Hp intensity, after which the magnetic coupling of the standard magnet is characterized by a flux Fl, Minimally acceptable for magnets of a given frame size. The output of the magnetic flux sensor 6 is induced by an electrical signal, to which the T-ory is amplified through the closed KEY 11 is fed to the input of the memory unit 13, where the voltage is fixed, K Fr (K = coefficients {) and. After that, 1SHYUCH 11 is opened and the device is ready to control the magnetism of the magnets of the appropriate size, and the order of operations performed by the device is determined by the software block 8,, 6 The test magnet is clamped between the poles of the nitreboard 1. Then t (see Fig. 2) from the output of the master oscillator 7 receives a voltage pulse U- to the input of the program block 8 and the input Installation O of the reversible counter 18.. From the output of block 8, at the time point, the control pulse Ura enters the magnetizing coils of the electromagnet. triggering magnetic field with intensity H (t). As a result, the magnet 3 is magnetized to a state of technical saturation. At the time tj from the output of block 8, a voltage pulse Ug arrives at the demagnetizing coils 5, causing a magnetic field pulse with intensity I5 (t), the amplitude of which is; It is equal to Hp, and the duration t is long enough for transient processes in the magnet body to end during time t. At time t. From the first output of block 8 to the first input of the coincidence element 15, a direct signal U is received. At the same time, an electrical signal with voltage Uq P is proportional to the flux HX p. the test magnet is fed to the input of the converter 10, in which it is converted from analog to discrete form, after which it is fed to the second input of the coincidence element 15. Due to the fact that the voltage Un is supplied to its first input, the reversible counter 18 will fix the number proportional to Fr,. At the time from the second output of block 8 to the converter 10, a start signal is received, and the magnet is again subjected to the demagnetization field. After that, the first input of comparator 12 receives an electrical signal with voltage Uq KRr At the time tg from the second output of block 8, the first inputs of elements 14 and 17 receive a direct signal 13, If 9 2 PPHUHJ, 5y and from the output of block 12 to the second input of the coincidence element 17 receives a direct signal, the ac output of the element 17 to the first input of block 20 receives a signal carrying information O and magnet magnitude Otherwise (Frd Rmin to the input of block 20: inverse flows).

signal U., indicating the use of a magnet.

At the same time, the second input of element 14 receives a discretely shaped signal proportional to the magnitude of the magnetic flux Fro and from the output of element 14 it is fed to the second input of the reversing counter 18. If (Фр - Фр2) -4 Д, where Д is the value determined by the measurement accuracy then a zero is fixed on the counter, and the second input of the fourth block AND 20 receives a signal from the output of the null indicator 19 and a signal "01 and from the output of the element 16 to the second input of the block 20 at the moment of time. the signal Ujg arrives that carries information about the validity of the magnet and its ability to retain its magnetic property after repeated, effects of demagnetizing fields with a strength | i- Hp.

Otherwise (/ Chr) the output zero indicator a 19 is present an inverse signal -jq The signal at the output of element 16 will also be inverse. The magnet will be certified as a defect.

The proposed device allows to increase the reliability of the magnetic properties of permanent magnets and, consequently, to improve the quality and reliability of both the magnets themselves and electrical products in general. The entire control cycle using the proposed device is made automatically, so its use will allow to increase labor productivity in the process of acceptance tests of magnets.

Claims (2)

1. USSR author's certificate No. 221167, Gr 01Я 33/12, 17.11.66. 2. USSR author's certificate No. 516980, Q 01T 33/12, 12/24/74. Yu Jz lU.I R 2