CN103822600B - The supersonic detection method of thin friction material Rotating fields slide bearing lubricating film thickness - Google Patents

Abstract

The invention discloses the supersonic detection method of a kind of thin friction material Rotating fields slide bearing lubricating film thickness, the method is on the basis of basic rigidity model method needs to obtain bearing shell Air Interface reference reflection echo signal, the echo-signal amplitude spectrum of matrix lining interface is obtained by thick lining bearing shell test specimen or Theoretical Calculation, obtain Control echo the most respectively, the frequency domain amplitude ratio of superposed signal and matrix lining interface echo during different thickness echo, and echo component and the matrix lining interface echo Amplitude Ration at a concrete frequency comprising thickness information is obtained by superposed signal frequency spectrum analysis method, thus obtain the reflectance value in film thickness measuring and finally determine lubrication film thickness value.Fluid lubrication when present invention achieves reflection echo signal superposition slides radially and thrust bearing submicron and the measurement of micron order lubrication film thickness.

Description

The supersonic detection method of thin friction material Rotating fields slide bearing lubricating film thickness

[technical field]

The design that the invention belongs to operation of industrial installation monitoring and tribology element is led with experimental check Territory, is specifically related to the supersonic detection method of a kind of thin friction material Rotating fields slide bearing lubricating film thickness.

[background technology]

The occasions such as sliding bearing is widely used at a high speed, accurate, heavily loaded, and become large electric power plant, water power Important core parts in the equipment such as unit, nuclear power station main circulation pump, high-speed precise machine tool.Fluid lubrication is sliding Dynamic bearing is dependent on what bearing shell and journal surface were separated by fluid lubrication film, and the characteristic of its lubricating film and state are certainly The service abilities such as the bearing capacity of sliding bearing, running stability and life-span, therefore convection cell lubricating film are determined The detection of the states such as thickness either Experimental comparison for theory of fluid lubrication study, or for sliding axle The monitoring running state held is the most significant.

Slide bearing lubricating film thickness is one of basic parameter of sliding bearing.Generally sliding bearing design with In Performance Calculation, need, by hypothesis physically and mathematical approximation, to obtain the minimum profit of sliding bearing Synovial thickness and thickness distribution, and determine other important parameter in sliding bearing design, such as lubrication mould Power, bearing capacity, width-diameter ratio etc..And the assumed condition in Theoretical Calculation and practical situation not quite identical, And the factor produced in bearing manufacture process and running makes lubricating film domain of the existence and thickness thereof It is difficult to accurate description.Therefore, in order to determine the impact of various assumed condition, and lubrication film thickness in operation Actual distribution, be required for research and propose the detection method of lubrication film thickness.

Slide bearing lubricating film is present between two interfaces of relative motion, and thickness is generally tens of the most micro-at submicron Between meter, and having the feature of real-time change, it is the biggest that these make the measurement of fluid lubrication film thickness have Challenge.Tradition lubrication film thickness detection method based on electric-resistivity method, capacitance method and optical means needs to destroy Surface of friction pair, or need a friction pair be transmission substance.Relative to these methods, ultrasound examination Method is without being modified surface of friction pair, and its penetration capacity having compensate for optical means and requires light transmission Deficiency, detection method based on ultrasonic technology has substantially for the detection of slide bearing lubricating film thickness Superiority.

It is typically based on the film dielectric layer method for measuring thickness of ultrasound wave time difference method, resonance method, former by measurement model Restriction in reason, its thickness measuring scope is typically in some tens of pm and above magnitude.Ultrasound wave rigidity model method root According to the relation of intermediate medium stiffness layer Yu ultrasonic reflection coefficient, the measurement scope of central fluid layer thickness is expanded Opening up ten microns of magnitudes to submicron, theoretical base has been established in the actual application for lubrication thickness ultrasound examination Plinth.The concrete measurement of lubrication thickness when ultrasound wave rigidity model method gives bearing shell-fluid film-axle journal three-decker Method.The echo amplitude at bearing shell-fluid film interface is carried out by this method with the echo of bearing shell-Air Interface Relatively, draw the reflectance value determined by thickness, material acoustics parameter etc., then according to reflection coefficient with Relation between thickness draws fluid film one-tenth-value thickness 1/10.

But, plain bearing bush is generally formed by casting or rolling by matrix and friction material layer two parts, Friction material layer is generally made up of alloy material, plays antifriction, embedding Tibetan abrasive particle, is easy to the effects such as maintenance, rubs Wipe material layer and be also referred to as the lining of bearing.Liner layer thickness is generally in the range of a few tenths of millimeter to 6mm, so, Ensure ultrasonic pachymetry is original do not destroy bearing arrangement superiority on the premise of, the measurement model of three-decker Reform into the version of bearing shell matrix-lining-fluid film-axle journal four layers.Rushing ultrasonic measurement with short pulse is Example, usual ultrasound wave occupies the pulse width of more than 3 wavelength in measured material, when frequency is 10MHz The bearing shell of ultrasound wave incidence steel-babbit structure time, ultrasound wave is about in the pulse width of babbit layer 1mm, and when using the long pulse transducer of 5MHz, this width value becomes 4.6mm, when bearing shell serves as a contrast When layer thickness is less than the half of this pulse width, ultrasonic pulse is the first He of four-layer structure measurement model The reflection echo of second contact surface will occur superposition phenomenon, and this is " thin friction material layer " or " thin lining in the present invention Layer " implication." thick lining " is distinguished the most as depicted in figs. 1 and 2 with " thin lining " bearing shell ultrasonic reflection echo-signal, Wherein, P_bFor bearing shell matrix-lining interface echo, P₁、P₂、P₃Return Deng being respectively lining-fluid film interface Ripple transmission repeatedly between lining, reflect to form, P_mThe superposition of each echo more than when being then thin lining situation Signal.When reflection echo generation superposition, just cannot recycle basic rigidity model method and obtain bearing shell-fluid The reflection coefficient of membrane interface, therefore, it is difficult to slide bearing lubricating film in most cases in practical engineering application Thickness measures.

[summary of the invention]

Present invention aims to deficiency of the prior art, it is provided that a kind of thin friction material Rotating fields The supersonic detection method of slide bearing lubricating film thickness, the method is according to the spectrum analysis side of time domain superposed signal Method, to the reflection echo containing thickness information at bearing shell lining-fluid film interface during thin friction material layer situation with The superimposed signal of bearing shell matrix-lining interface reflection echo carries out frequency-domain analysis, extract in echo with fluid The information that film thickness change is relevant, and then obtain fluid layer interface reflection coefficients and lubrication film thickness value.

For achieving the above object, the present invention adopts the following technical scheme that

The supersonic detection method of thin friction material Rotating fields slide bearing lubricating film thickness, comprises the steps:

1) thickness measured with the thin friction material identical material of Rotating fields sliding bearing by ultrasonic testing system is rubbed Wipe time domain echo-signal p of the bearing shell matrix-lining interface of material layer bearing shell test block_b(t), and time domain echo is believed Number p_bT its frequency domain amplitude spectrum that () obtains through fast Fourier transform | P_b(ω) |, then measure to be detected thin rub Wipe the material layer sliding bearing Control echo signal p when bearing shell-Air Interface_a(t), and measure thin friction material Bed of material plain bearing bush-fluid film interface superposition echo-signal p_mT (), wherein, thin friction material layer is that it is thick Degree is less than the bearing shell lining of ultrasonic transducer ultrasonic pulse width half, and thick friction material layer is that its thickness is big In the bearing shell lining equal to ultrasonic transducer ultrasonic pulse width half；

2) respectively to step 1) in obtain Control echo signal p_a(t) and superposition echo-signal p_mT () is carried out quickly Fourier transformation, obtains the frequency domain amplitude spectrum of Control echo signal | P_a(ω) | and the frequency domain amplitude of superposition echo-signal Spectrum | P_m(ω) |, its result the most respectively with step 1) in obtain bearing shell matrix-lining interface frequency domain amplitude spectrum P_b(ω) | compare, obtain the Amplitude Ratio Q of Control echo signal and matrix-lining interface echo_a(ω) with superposition echo Signal and the Amplitude Ratio Q of matrix-lining interface echo_m(ω)；

3) according to step 2) the Amplitude Ratio Q of the Control echo signal that obtains and matrix-lining interface echo_a(ω) knot Close its crest frequency ω_as, calculate crest frequency ω_asTo (1+10%) ω_asIn frequency field and the ginseng of two end points Examine different interface echo composition Amplitude Ratio k in echo-signal_a(ω_a), its computing formula is as follows:

$k_a^2\left({\mathrm{\ω}}_a\right)+(4{\cos }^2{\mathrm{\ω}}_a{t}_0-2)\·k_a\left({\mathrm{\ω}}_a\right)+\[1-Q_a^2\left({\mathrm{\ω}}_a\right)\]=0---\left(1\right)$

In formula: t₀For ultrasound wave by time used by thin liner layer thickness, ω_aFor Control echo signal at ω_asExtremely (1+10%) ω_asIn the range of frequency, Q_a(ω_a) it is Control echo signal with matrix-lining interface echo at ω_aPlace Amplitude Ratio；

4) according to step 2) the Amplitude Ratio Q of the superposed signal echo that obtains and matrix-lining interface echo_m(ω) knot Close its crest frequency ω_ms, calculate crest frequency ω_msIn the superposition echo-signal at place, different interface echos become framing Degree compares k_m(ω_ms), its computing formula is as follows:

$k_m^2\left({\mathrm{\ω}}_{ms}\right)+2k_m\left({\mathrm{\ω}}_{ms}\right)+\[1-Q_m^2\left({\mathrm{\ω}}_{ms}\right)\]=0---\left(2\right)$

In formula: Q_m(ω_ms) it is that superposed signal echo compares Q with matrix-lining interface echo amplitude_m(ω) at crest frequency ω_msThe Amplitude Ratio at place；

5) by step 4) in different interface echo composition Amplitude Ratio k in the superposition echo-signal that obtains_m(ω_ms) with Step 3) in different interface echo composition Amplitude Ratio k in the Control echo signal that obtains_a(ω_ms) in frequencies omega_msPlace Value compare, obtain lubricate film thickness measuring time echo-signal reflection R, finally according to basic rigidity model Method formula of oil film combines reflection R and obtains thin friction material Rotating fields slide bearing lubricating film thickness h.

The present invention further improvement is that, step 5) in, basic rigidity model method formula of oil film is:

$h=\frac{{\mathrm{\ρc}}^2}{{\mathrm{\ωz}}_1{z}_2}\sqrt{\frac{R^2{(z_1+z_2)}^2-{(z_1-z_2)}^2}{1-R^2}}---\left(3\right)$

In formula: ρ is fluid media (medium) density, unit is kg/m³；

C is the velocity of sound of fluid media (medium), and unit is m/s；

z₁For bearing shell lining material acoustic impedance, unit is kg/ (m²·s)；

z₂For axle journal acoustic impedance, unit is kg/ (m²·s)；

ω is ultrasonic reflection angular frequency, and unit is rad/s.

Compared with prior art, the present invention has the following technical effect that:

The supersonic detection method of a kind of thin friction material Rotating fields slide bearing lubricating film thickness of the present invention, the party Method is to superposition echo reflection when having a slide bearing lubricating film thickness ultrasonic measurement of thin friction material Rotating fields Signal is analyzed, and obtains the base that the lining containing thickness information-lubricating film interface echo composition is constant with holding The Amplitude Ration of body-lining interface echo component, and compare with this Amplitude Ration during Control echo signal, Thus echo reflection coefficient when obtaining film thickness measuring and thickness result.The present invention solves in engineer applied normal The thin friction material Rotating fields sliding bearing micron order seen and a measurement difficult problem for submicron order lubrication film thickness, open up Open up the range of application of ultrasound wave lubrication film thickness measuring method.

[accompanying drawing explanation]

Fig. 1 thickness friction material layer sliding bearing ultrasonic reflection echo time-domain signal figure；

Fig. 2 thin friction material layer sliding bearing ultrasonic reflection echo time-domain signal figure；

Thickness and reflection coefficient graph of relation during Fig. 3 babbit-oil film-steel medium；

Fig. 4 thickness lining bearing shell test block matrix-lining interface echo time-domain signal figure；

Fig. 5 thickness lining bearing shell test block matrix-lining interface echo-signal amplitude spectrum；

Superposition echo time-domain signal comparison diagram when Fig. 6 thin lining sliding bearing Control echo and different thickness；

Superposition echo-signal amplitude spectrum when Fig. 7 thin lining sliding bearing Control echo and different thickness；

Superposition echo-signal and matrix-lining interface when Fig. 8 thin lining sliding bearing Control echo and different thickness Echo Amplitude Ration figure；

Lining-lubricating film interface echo and matrix-lining interface echo during Fig. 9 thin lining sliding bearing difference thickness Amplitude Ration repetitive measurement result figure；

Figure 10 thin lining sliding bearing Control echo signal lining-Air Interface echo returns with matrix-lining interface Wave amplitude is than repetitive measurement result figure；

Measurement of reflection-factor result figure during Figure 11 thin friction material layer sliding bearing difference thickness；

Figure 12 thin friction material layer slide bearing lubricating film thickness testing result with thickness comparison diagram is set.

Wherein: 1 is bearing shell matrix-lining interface echo P_b；2 is lining-one time, fluid film interface echo P₁；3 For lining-fluid film interface second trip echo P₂；4 is lining-three times, fluid film interface echo P₃；5 is lining-stream Four echo P of body membrane interface₄；6 is bearing shell matrix-lining interface echo and lining-fluid film interface multiecho Superposed signal P_m；7 is Control echo；8 increase direction for thickness.

[detailed description of the invention]

Below in conjunction with the accompanying drawings the present invention is described in further detail:

See Fig. 3 to 12, the ultrasound detection of the present invention thin friction material Rotating fields slide bearing lubricating film thickness Method, comprises the steps:

Step 1) measured and the thin friction material identical material of Rotating fields sliding bearing by ultrasonic testing system Time domain echo-signal p of the bearing shell matrix-lining interface of thick friction material layer bearing shell test block_b(t), and time domain is returned Ripple signal p_bT its frequency domain amplitude spectrum that () obtains through fast Fourier transform | P_b(ω) |, then measure to be detected The thin friction material layer sliding bearing Control echo signal p when bearing shell-Air Interface_a(t), and measure thin rubbing Wipe material layer plain bearing bush-fluid film interface superposition echo-signal p_mT (), wherein, thin friction material layer is Its thickness is less than the bearing shell lining of ultrasonic transducer ultrasonic pulse width half, and thick friction material layer is that it is thick Degree is more than or equal to the bearing shell lining of ultrasonic transducer ultrasonic pulse width half；

2) respectively to step 1) in obtain Control echo signal p_a(t) and superposition echo-signal p_mT () is carried out quickly Fourier transformation, obtains the frequency domain amplitude spectrum of Control echo signal | P_a(ω) | and the frequency domain amplitude of superposition echo-signal Spectrum | P_m(ω) |, its result the most respectively with step 1) in obtain bearing shell matrix-lining interface frequency domain amplitude spectrum |P_b(ω) | compare, obtain the Amplitude Ratio Q of Control echo signal and matrix-lining interface echo_a(ω) with superposition echo Signal and the Amplitude Ratio Q of matrix-lining interface echo_m(ω)；

3) according to step 2) the Amplitude Ratio Q of the Control echo signal that obtains and matrix-lining interface echo_a(ω) knot Close its crest frequency ω_as, calculate crest frequency ω_asTo (1+10%) ω_asIn frequency field and the ginseng of two end points Examine different interface echo composition Amplitude Ratio k in echo-signal_a(ω_a), its computing formula is as follows:

$k_a^2\left({\mathrm{\ω}}_a\right)+(4{\cos }^2{\mathrm{\ω}}_a{t}_0-2)\·k_a\left({\mathrm{\ω}}_a\right)+\[1-Q_a^2\left({\mathrm{\ω}}_a\right)\]=0---\left(1\right)$

In formula: t₀For ultrasound wave by time used by thin liner layer thickness, ω_aFor Control echo signal at ω_asExtremely (1+10%) ω_asIn the range of frequency, Q_a(ω_a) it is Control echo signal with matrix-lining interface echo at ω_aPlace Amplitude Ratio；

4) according to step 2) the Amplitude Ratio Q of the superposed signal echo that obtains and matrix-lining interface echo_m(ω) knot Close its crest frequency ω_ms, calculate crest frequency ω_msIn the superposition echo-signal at place, different interface echos become framing Degree compares k_m(ω_ms), its computing formula is as follows:

$k_m^2\left({\mathrm{\ω}}_{ms}\right)+2k_m\left({\mathrm{\ω}}_{ms}\right)+\[1-Q_m^2\left({\mathrm{\ω}}_{ms}\right)\]=0---\left(2\right)$

In formula: Q_m(ω_ms) it is that superposed signal echo compares Q with matrix-lining interface echo amplitude_m(ω) at crest frequency ω_msThe Amplitude Ratio at place；

5) by step 4) in different interface echo composition Amplitude Ratio k in the superposition echo-signal that obtains_m(ω_ms) with Step 3) in different interface echo composition Amplitude Ratio k in the Control echo signal that obtains_a(ω_ms) in frequencies omega_msPlace Value compare, obtain lubricate film thickness measuring time echo-signal reflection R, finally according to basic rigidity model Method formula of oil film combines reflection R and obtains thin friction material Rotating fields slide bearing lubricating film thickness h.

Wherein, step 5) in, basic rigidity model method formula of oil film is:

$h=\frac{{\mathrm{\ρc}}^2}{{\mathrm{\ωz}}_1{z}_2}\sqrt{\frac{R^2{(z_1+z_2)}^2-{(z_1-z_2)}^2}{1-R^2}}---\left(3\right)$

In formula: ρ is fluid media (medium) density, unit is kg/m³；

C is the velocity of sound of fluid media (medium), and unit is m/s；

z₁For bearing shell lining material acoustic impedance, unit is kg/ (m²·s)；

z₂For axle journal acoustic impedance, unit is kg/ (m²·s)；

ω is ultrasonic reflection angular frequency, and unit is rad/s.

In order to the present invention is further appreciated that, now it is described in further detail.

(1) general thought of the present invention

For time domain echo-signal superimposed during bearing shell matrix-lining-fluid film-axle journal four-layer structure, due to The change of thickness does not affect the echo amplitude of bearing shell matrix-lining interface, namely obtains in different film thickness measuringes Superposition echo-signal in p_bComposition is changeless, material parameter determine.So, obtain Lining-fluid film interface echo composition containing thickness information and p in superposition echo-signal_bAmplitude Ration, then To lining-Air Interface echo and p_bAmplitude Ration as reference amplitude ratio, by two above and p_bAmplitude Ration It is assured that reflection coefficient during different thickness, thus obtains film thickness value according to basic rigidity model method.

(2) the solving of superposed signal echo and basal body interface echo amplitude ratio

For lubricating the ultrasound examination of thickness, superposition echo-signal p during thin lining_mT () is by matrix-lining circle Face echo-signal p_bThe multiple-reflection echoes signal p at (t) and lining-lubricating film interface₁(t)、p₂(t)、p₃T () etc. fold Adding and form, the time interval between these echoes is determined with its material properties by liner layer thickness, if ultrasound wave leads to The time used by liner layer thickness that crosses is t₀, then coming and going the time interval between the echo that alloy lining is formed is 2t₀。 Due to the difference of the first and second boundary material parameters, and different lubricant film layer thickness is to second contact surface echo The impact of amplitude so that p₁(t) and p_bT () has had certain amplitude difference, and p₁(t)、p₂(t)、p₃Between echoes such as (t) Amplitude difference be to be formed due to the different produced differential declines through alloy-layer number of times.First, neglect Slightly p₂(t)、p₃T echoes such as () is to p_mThe impact of (t), if p_mT () is 2t by time interval₀Two echo-signals p_b(t+t₀) and p₁(t-t₀) formed, and set matrix-lining interface echo-signal p_bT the Fourier transformation of () is p_b(ω), According to the correlation theorem of Fourier transformation, can obtain

$\begin{array}{c}|F\[p_m\left(t\right)\]|=|F\[p_b(t+t_0)+p_1(t-t_0)\]|\\ =|e^{{\mathrm{j\ωt}}_0}{P}_b\left(\mathrm{\ω}\right)+k\left(\mathrm{\ω}\right)e^{-{\mathrm{j\ωt}}_0}{P}_b\left(\mathrm{\ω}\right)|\end{array}$

$=\sqrt{{\[1-k\left(\mathrm{\ω}\right)\]}^2+4k\left(\mathrm{\ω}\right){\cos }^2{\mathrm{\ωt}}_0}\left|P_b\left(\mathrm{\ω}\right)\right|---\left(4\right)$

Wherein, k (ω) is the Amplitude Ration of two pulse repetition at different frequency in frequency domain.Then p_m(t) and p_bT () is at frequency domain In Amplitude Ration Q (ω) be

$Q\left(\mathrm{\ω}\right)=\frac{\left|P_m\left(\mathrm{\ω}\right)\right|}{\left|P_b\left(\mathrm{\ω}\right)\right|}=\sqrt{{\[1-k\left(\mathrm{\ω}\right)\]}^2+4k\left(\mathrm{\ω}\right){\cos }^2{\mathrm{\ωt}}_0}---\left(5\right)$

(3) the solving of difference interface echo composition Amplitude Ratio during superposed signal

If can obtain in advance | P_m(ω) |, then can pass through thin lining echo p_mThe amplitude spectrum of (t) and | P_b(ω) | ratio Obtain Q (ω), then obtain p during different thickness by solving formula (5) equation₁(t) and p_bThe frequency domain amplitude of (t) Ratio k (ω), the reference amplitude ratio then obtained with lining-Air Interface compares, thus obtains reflection coefficient With film thickness value.So, it is necessary to before carrying out the lubrication thickness detection of thin lining, by processing identical material Thick lining bearing shell test block, and use identical ultrasonic testing system, obtain matrix-lining interface echo p_b(as Fig. 1 shows), this is typically easily realization, it is possible to obtained by the Theoretical Calculation of material acoustics parameter | P_b(ω) |, And if being replaced the p obtained by the thick lining bearing shell of similar materials_b, the accurate of final film thickness measuring result can be affected Degree, but have no effect on the monitoring to Thickness Variation trend.

After obtaining Q (ω), formula (5) becomes the following equation containing k (ω).

k²(ω)+(4cos²ωt₀-2)·k(ω)+[1-Q²(ω_s)]=0 (6)

And from formula (5), Q (ω) be with frequency by cosine manner fluctuate on the occasion of curve, be located at ultrasound wave The peak value of echo mid frequency vicinity Q (ω) is Q (ω_s), ω_sFor the crest frequency of Q (ω), then above formula becomes

k²(ω_s)+2k(ω_s)+[1-Q²(ω_s)]=0 (7)

The p containing thickness information when can be obtained different film thickness measuring by formula (7)₁T p that () is constant with holding_bT () exists ω_sAmplitude Ration k (ω at frequency_s)。

(4) the solving of ultrasonic echo reflection coefficient and thickness during superposed signal

Due to ultrasound wave at the reflection coefficient of bearing shell-Air Interface close to 1 (R=0.999982 when bearing shell is steel, For R=0.999961 during babbit), need to obtain reflection echo conduct during bearing shell-air conditions at measuring point Control echo signal, the echo-signal obtained when then actual thickness being detected compared with Control echo signal, Obtaining the reflection coefficient of approximation, concrete grammar is as follows.

Control echo signal p by the thin lining bearing shell-Air Interface detected in advance_aT (), according to formula (5), formula (7) p during available Air Interface₁(t) and p_bT () is at ω_sAmplitude Ration k at frequency_a(ω_s).Then during different thickness Echo is at ω_sThe reflection coefficient at place is

$R\left({\mathrm{\ω}}_s\right)=\frac{k\left({\mathrm{\ω}}_s\right)}{k_a\left({\mathrm{\ω}}_s\right)}---\left(8\right)$

It is true that p_mP in (t)₂(t)、p₃Echo component such as (t), right | P_m(ω) |, namely the amplitude of Q (ω) has small Impact, and simultaneously striked by k_a(ω_s) also include multiecho p in lining-Air Interface₂(t)、p₃(t) Deng impact, and final ratio R (ω_s) then cut down the impact for final thickness result of this some factors. So, R (ω is tried to achieve_sAfter), according to the most available thin lining sliding bearing of following basic rigidity model method formula Lubrication film thickness value.

$h=\frac{{\mathrm{\ρc}}^2}{{\mathrm{\ωz}}_1{z}_2}\sqrt{\frac{R^2{(z_1+z_2)}^2-{(z_1-z_2)}^2}{1-R^2}}---\left(3\right)$

Wherein, the bush material acoustic impedance z corresponding to lubricating film both sides₁With axle journal acoustic impedance z₂, Yi Jiliu Body layer density p, velocity of sound c are determined by material properties.Babbit-oil film-steel the medium obtained according to formula (3) Time thickness and reflection coefficient theory relation curve such as Fig. 3, it can be as guidance and the thickness measuring frequency selection The adjunct test of measurement result.

Seeing Fig. 4-10, technical scheme mainly includes separable matrix-lining in implementation process The acquisition of Waves Investigation for Interface Echo Signal, the acquisition of thin lining bearing shell-Air Interface Control echo signal, solve superposition letter Number echo and basal body interface echo amplitude ratio, solve different interface echo composition Amplitude Ratios in superposed signal, super Sound echo reflection coefficient and thickness some steps such as solve.Ultrasonic transducer with mid frequency as 10MHz Illustrating as a example by detecting, key step is as follows.

1) time domain waveform p is obtained by thick lining bearing shell test block_bT () (as shown in Figure 4), it is through fast Fourier The amplitude spectrum that conversion obtains | P_b(ω) | (as shown in Figure 5).Secondly, thin lining sliding axle to be detected is measured Hold the Control echo signal when bearing shell-Air Interface, and the echo-signal when difference lubrication thickness p_mEcho-signal (as shown in Figure 6) when (t), Control echo signal and different thickness.

2) echo-signal of Control echo signal and different thickness is carried out fast Fourier transform (such as Fig. 7 institute Show), and as shown in formula (5) and Fig. 5 | P_b(ω) | compare, obtain ratio Q (ω) curve as shown in Figure 8.

3) after obtaining Q (ω) ratio curve, formula (7) k (ω during different-thickness lubricating film can be obtained_s) value (as Shown in Fig. 9), in like manner, the Q (ω) of Control echo the Control echo k being worth to_a(ω_s) value as shown in Figure 10, Its crest frequency ω_sFor 10.4MHz, and as seen from Figure 8, attached at mid frequency 10MHz during different thickness Near ω_sNot with the ω of Control echo_sBe completely superposed, so in order to obtain accurately different thickness time peak value frequency Rate ω_sThe reflection coefficient at place, is determined Control echo at its ω by formula (6)_sThe k value of neighbouring frequency band, repeatedly Measurement result shows at this frequency band reference signal lining-Air Interface echo component and | P_b(ω) | have more stable K value.

4) reflection coefficient of echo-signal when being obtained different thickness by formula (8), then, according to reflection coefficient Result is obtained thin lining bearing shell lubrication thickness testing result by formula (3).As it is shown on figure 3, when less thickness, The method Measurement Resolution and accuracy are higher.Due to bearing shell surface roughness and the impact of lubricant characteristics, Submicron order thickness result can be obtained during actually detected, and 0 film thickness value can be infinitely close to, and can not 0 film thickness value can be there is.The method is near thick 10 μm of relatively thick film, and reflectance value moves closer in 1, relatively Big Thickness Variation is reflected, by the noise during detection and spectrum analysis by the least reflection coefficient change Making the thickness resolution in the range of this relatively low etc. the error brought, this is former by basic rigidity model method Reason is determined.When thickness reaches more than 7.5 μm, although owing to the fluctuation of error makes the thickness of single Measurement result can not reflect the thickness state of reality, but the distribution trend of repetitive measurement result and its average can be relatively Reflect well change and the one-tenth-value thickness 1/10 thereof of thickness in the range of this so that the method can be used in micron and sub-micro The detection of meter level lubrication film thickness.Wherein, basic rigidity model method determine larger film thickness or close to Film thickness measuring resolution in 10 μm film thickness range is relatively low, and noise jamming and spectrum analysis during detection miss The thickness result fluctuation that official post obtains in the range of this is bigger.Thickness in the range of this is used and the most quickly surveys Amount, is reflected change and the one-tenth-value thickness 1/10 thereof of thickness in the range of this by the distribution trend of repetitive measurement result and average.

Embodiment:

Actual being measured as is carried out with the thrust slide bearing lubrication film thickness to 0.5mm thickness babbitlining Example, and design thickness analog, produce different-thickness with the precision piezoelectric actuator with closed loop control Lubricant film layer, the film thickness measuring result that obtains of the method for the invention and piezo-activator feedback thickness will be used Degree compares, and illustrates the effectiveness of supersonic detection method of the present invention.When measurement obtains different thickness The reflection coefficient of echo-signal as shown in figure 11, in figure arrange thickness be closed loop piezo-activator reading show The film thickness value shown.Film thickness measuring result is obtained and the comparison that thickness is set by formula (3) according to reflection coefficient result As shown in figure 12.The measurement result fluctuation obtained during larger film thickness is relatively big, and this is to be divided with frequency spectrum by measurement noise Analysis error is brought, and is also to be determined by basic rigidity model method principle, although the measurement result of single can not Accurately reflect the thickness state of reality, but the distribution trend of repetitive measurement result and average thereof preferably reflect The change of thickness and one-tenth-value thickness 1/10 thereof.Repetitive measurement result in figure reflects the correctness of the method for the invention.

Above content is to combine concrete preferred implementation further description made for the present invention, no Can assert that the detailed description of the invention of the present invention is only limitted to this, for the ordinary skill of the technical field of the invention For personnel, without departing from the inventive concept of the premise, it is also possible to make some simple deduction or replace, All should be considered as belonging to the present invention and be determined scope of patent protection by the claims submitted to.

Claims (2)

1. The supersonic detection method of the thinnest friction material Rotating fields slide bearing lubricating film thickness, it is characterised in that Comprise the steps:

   1) thickness measured with the thin friction material identical material of Rotating fields sliding bearing by ultrasonic testing system is rubbed Wipe time domain echo-signal p of the bearing shell matrix-lining interface of material layer bearing shell test block_b(t), and time domain echo is believed Number p_bT its frequency domain amplitude spectrum that () obtains through fast Fourier transform | P_b(ω) |, then measure to be detected thin rub Wipe the material layer sliding bearing Control echo signal p when bearing shell-Air Interface_a(t), and measure thin friction material Bed of material plain bearing bush-fluid film interface superposition echo-signal p_mT (), wherein, thin friction material layer is that it is thick Degree is less than the bearing shell lining of ultrasonic transducer ultrasonic pulse width half, and thick friction material layer is that its thickness is big In the bearing shell lining equal to ultrasonic transducer ultrasonic pulse width half；

   2) respectively to step 1) in obtain Control echo signal p_a(t) and superposition echo-signal p_mT () is carried out quickly Fourier transformation, obtains the frequency domain amplitude spectrum of Control echo signal | P_a(ω) | and the frequency domain amplitude of superposition echo-signal Spectrum | P_m(ω) |, its result the most respectively with step 1) in obtain bearing shell matrix-lining interface frequency domain amplitude spectrum |P_b(ω) | compare, obtain the Amplitude Ratio Q of Control echo signal and matrix-lining interface echo_a(ω) with superposition echo Signal and the Amplitude Ratio Q of matrix-lining interface echo_m(ω)；

   3) according to step 2) the Amplitude Ratio Q of the Control echo signal that obtains and matrix-lining interface echo_a(ω) knot Close its crest frequency ω_as, calculate crest frequency ω_asTo (1+10%) ω_asIn frequency field and the ginseng of two end points Examine different interface echo composition Amplitude Ratio k in echo-signal_a(ω_a), its computing formula is as follows:

   $k_a^2\left({\mathrm{\ω}}_a\right)+(4{\cos }^2{\mathrm{\ω}}_a{t}_0-2)\·k_a\left({\mathrm{\ω}}_a\right)+\[1-Q_a^2\left({\mathrm{\ω}}_a\right)\]=0---\left(1\right)$

   In formula: t₀For ultrasound wave by time used by thin liner layer thickness, ω_aFor Control echo signal at ω_asExtremely (1+10%) ω_asIn the range of frequency, Q_a(ω_a) it is Control echo signal with matrix-lining interface echo at ω_aPlace Amplitude Ratio；

   4) according to step 2) the Amplitude Ratio Q of the superposed signal echo that obtains and matrix-lining interface echo_m(ω) knot Close its crest frequency ω_ms, calculate crest frequency ω_msIn the superposition echo-signal at place, different interface echos become framing Degree compares k_m(ω_ms), its computing formula is as follows:

   $k_m^2\left({\mathrm{\ω}}_{ms}\right)+2k_m\left({\mathrm{\ω}}_{ms}\right)+\[1-Q_m^2\left({\mathrm{\ω}}_{ms}\right)\]=0---\left(2\right)$

   In formula: Q_m(ω_ms) it is that superposed signal echo compares Q with matrix-lining interface echo amplitude_m(ω) at crest frequency ω_msThe Amplitude Ratio at place；

   5) by step 4) in different interface echo composition Amplitude Ratio k in the superposition echo-signal that obtains_m(ω_ms) with Step 3) in different interface echo composition Amplitude Ratio k in the Control echo signal that obtains_a(ω_a) in frequencies omega_msPlace Value is compared, and the reflection R of echo-signal when obtaining lubricating film thickness measuring, finally according to basic rigidity model method Formula of oil film combines reflection R and obtains thin friction material Rotating fields slide bearing lubricating film thickness h.
2. The ultrasound detection side of thin friction material Rotating fields slide bearing lubricating film thickness the most as claimed in claim 1 Method, it is characterised in that step 5) in, basic rigidity model method formula of oil film is:

   $h=\frac{{\mathrm{\ρc}}^2}{{\mathrm{\ωz}}_1{z}_2}\sqrt{\frac{R^2{(z_1+z_2)}^2-{(z_1-z_2)}^2}{1-R^2}}---\left(3\right)$

   In formula: ρ is fluid media (medium) density, unit is kg/m³；

   C is the velocity of sound of fluid media (medium), and unit is m/s；

   z₁For bearing shell lining material acoustic impedance, unit is kg/ (m²·s)；

   z₂For axle journal acoustic impedance, unit is kg/ (m²·s)；

   ω is ultrasonic reflection angular frequency, and unit is rad/s.