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TU 14-1-3074-80

Appendix 3

to TU 14−1-3074−80

Methodical instruction
by measuring the temperature coefficient of frequency
with longitudinal and torsional vibrations

1. Purpose of the installation

The installation is designed to measure the temperature coefficient of frequency during longitudinal and torsional vibrations of samples up to 151 mm long and a cross section of no more than 10x20 mm and Ø up to 10 mm. The sample material must have a magnetostrictive effect and have a residual magnetization flux of at least 1500 gauss.

2. Composition of the installation

2.1. Generator of standard signals type G4−42.

2.2. Electronic frequency counter type Ch3−36.

2.3. Oscilloscope type C1−19B.

2.4. Device of type НМ89М-8.

2.5. Devices for magnetizing samples.

2.6. Attachments with measuring coils.

2.7. Multi-position switch.

2.8. Thermostat.

2.9. Cryostat.

2.10. Thermometers for measuring temperatures from -70 ° C to + 100 ° C with a graduation of no more than 2 ° C.

Note. It is allowed to use other equipment, devices and fixtures that ensure the implementation of this instruction and according to the accuracy class not lower than those indicated.

3. MEASURING THE TEMPERATURE FREQUENCY COEFFICIENT (TKCH)

3.1. Assemble the block diagram shown in fig. 1.

3.2. Switch on the devices and warm them up for 30 minutes.

3.3. Magnet samples:

a) to excite longitudinal oscillations — in a solenoid with a field strength of at least 10 oersted;

b) to excite torsional vibrations, passing through them a current of at least 2A in the axial direction for 2−5 sec.

3.4. Insert the samples into the measuring coils so that the center of the sample is approximately aligned with the center of the coil.

3.5. Set the handles on the devices to the following positions:

a) on the generator:

  • — set the range switch to the range corresponding to the expected resonance frequency of the sample;
  • — set the «exit» regulators to the right until they stop;
  • — tumblers «Ten. HF «," Level K «turn on in the upper position;
  • — use the regulator «Level setting K» to set the arrow on the scale of the device to the position «K»;

b) on the frequency meter:

  • — turn all the toggle switches to the upper position;
  • — set the type of work switch to the «Control» position and check the correct operation of the frequency meter, then to the «Frequency A» position;
  • — set the «Indication time» switch to a position convenient for counting (1 or 5 sec);
  • — set the «Count time» switch to the position corresponding to the registration of at least 5 significant digits on the scoreboard;

c) on the oscilloscope:

  • — put the double switch «Synchronization» in the «Railway» position;
  • — put the double switch «Sweep duration» in the «100» position and smoothly set the duration of the sweep, convenient for work;
  • — double switch for calibration by duration — to position «2»;
  • — switch «Top. Plates «and» Horiz. Plates «to the» Strength. U «and» Strengthen. X «respectively;
  • — put the other switches in a position convenient for operation;

d) on the device НМ89М-8:

  • — Set the regulator to the middle position;
  • — switches «0» and «5 — 50 Hz» to position and 50 Hz, respectively.

3.6. By smoothly changing the generator frequency, find the resonant frequency of the sample by the maximum deviation of the arrow of the НМ89М-8 instrument or by the maximum signal amplitude on the oscilloscope screen, corresponding to Fig. 2.

3.7. Make sure that the resonance is not false, for which switch the toggle switch «5 — 50 Hz» of the НМ89М-8 device to the «5 Hz» position. With false resonance, the signal amplitude on the oscilloscope screen decreases significantly.

3.8. Using a frequency meter, record the resonance frequency of the sample at room temperature .

3.9. Place the coils with samples in a thermostat (cryostat) heated (cooled) to the specified temperature + 5 ° C.

3.10. Withstand the samples at the specified temperature for at least 30 minutes.

3.11. Measure the resonance frequency in accordance with paragraphs 3.6, 3.7.

3.12. Determine the value of TKCH by the formula:

, where

 — resonant frequency at room temperature, Hz;

 — resonant frequency at a given heating (cooling) temperature, Hz;

 — room temperature, ° С;

 — preset heating (cooling) temperature, ° С

Notes:

1. Measurement of resonance frequencies and to carry out without removing samples from the coils.

2. Allowed measurement and in any sequence.