SU1538100A1 - Method of determining cavitation endurance of parts - Google Patents

Abstract

The invention relates to wear tests and can be used in the engine industry to determine the cavitation resistance of the material used to make cylinder liners, cylinder heads, turbo-compressor housings, and other vibro-loaded parts. The purpose of the invention is to improve the accuracy of testing by taking into account the parameters of operation and material properties of the part. Excite the sample 4, ultrasonic vibration is determined parameter σ _yc cavitation resistance material sample σ _{yc ^{= (F O Σ O.)}} / (V O ρ), and the resilience of the items is judged by the maximum allowable time T _ave operation: T _ave = (H _pr σ _us ^. Ρ) / F _d σ _d , where F _about and F _d - the oscillation frequency of the sample and details

V ₀ - sample wear rate

σ _about and σ _d - voltage on the surface of the sample and parts

ρ - material density

H _pr - limiting the depth of destruction. 1 ill., 1 tab.

Description

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31

The invention relates to the field of wear testing and can be used in engine building to determine the cavitation resistance of a material used to make cylinder liners, cylinder heads, turbo-compressor housings and other vibration-loaded, water-cooled parts of internal combustion engines,

The purpose of the invention is to improve the accuracy of testing by taking into account the parameters of operation and material properties of the part.

The drawing shows an installation for implementing the method.

The device consists of an ultrasonic generator 1 with a magnetostriction vibrator 2 and a concentrator 3, test sample 4, bath 5 with liquid (water) “Sample 4 is placed in bath 5 filled with liquid. A heating element 6 and a thermostat are connected to the bath 5.

The method is implemented as follows. Place sample 4 of the part material in the liquid bath 5, with the addition of the ultrasonic generator J and the magnetostrictive vibrator 2 imitate the real conditions of wear. By exciting ultrasound oscillations in the sample 4, a constant frequency fc and amplitude are set for a fixed time using a heating element 6 and thermostat 7 to set the temperature of the liquid in the bath 5, determine the sample wear rate V0 and the voltage 60 and 6q the sample surface of the part and part material, the 6 v cavitational resistance index of the sample material is determined from the ratio

& itr

fp-6c

V.-f

and the resistance of the part when it oscillates with a frequency f0 is judged by the maximum allowable time T „of work:

etc

h np-scout I f, -6 /

f h

-the density of the material;

- the maximum depth of destruction is permissible.

Q

five

0 5

Q., O 5

004

In addition, the constant frequency of the surface oscillations is maintained by stabilizing the current and voltage applied to the oscillator.

Primer p. The cavitation resistance of six samples of various materials (gray cast iron with a lamellar graphite, cast iron doped with a lamellar graphite form, vermicular cast iron, high-strength cast iron with a spherical graphite form, chromium steel of grade ST 34XM, and aluminum alloy of the brand AL4) is determined. The tests were carried out on an ultrasonic generator with a magnetostriction vibrator, samples of materials are immersed in a water bath to a depth of 4 mm, the generator power is 1, 6 kW, the sample oscillation frequency f0 is 20 kHz, the amplitude of oscillations Ac is 0.01 mm, and Life on the end surface of the sample 235 MFa steel 34XM.

For cylinder liners of internal combustion engines, the oscillation frequency fo and the voltage can be determined by the known formulas, and the maximum permissible destruction depth hn is set to 0.75 h, where n is the thickness of the cylinder sleeve, m.

The results of determining the maximum permissible operating time of the diesel plug J24H15 / 18 are shown in the table.

The data in the table, based on the processing of experimental materials, show that the sample wear rate and the cavitational durability of cast iron substantially depend on its density. For example, the increase in the density of cast iron from 6.45 to 6.61, i.e. only 2.5%, leads to an increase in cavitation resistance 2.5 times.

The maximum permissible operating time of the 12ЧН15 / 18 diesel bushings also strongly depends on the cavitation resistance and for the values given in the table lies within 750-21200 h, i.e. the difference is 28.3 times.

Claims (1)

Formula and addiction Method for determining cavitation resistance of parts, which consists in placing a sample of the material of the part 5 into a bath with a liquid, imitate actual wear conditions by vibrating the surface of a sample of a material with a constant frequency and amplitude in 51538 for a fixed time, and according to the parameter of sample wear, the cavitation resistance of a part under actual operating conditions is judged, which is the fact that, in order to increase the test accuracy, the indicator of the navigation resistance of a material sample is determined from the ratio ten fo & o Vo f and as the parameter of sample wear, the maximum permissible time T „is determined15 t h pr- bus- p where b is the maximum permissible depth of destruction, m is f0 and tt) is the sample oscillation frequency parts c f; V0 — sample wear rate, m / s; voltage on the surface of the sample and parts, kgf / mg; material density, kg / m3. Plastinata The same Vermicul rna Spherical Chromista Cast, AP4 14.4 8.6 6.95 2.78 1.04 10.0 2.4 6.0 7.0 17.0 57.5 6.3 820 2200 2570 6360 21200 750