CN106248379A - A kind of bearing with solid lubricant accelerated life test loading spectrum method for designing - Google Patents

Abstract

The present invention relates to a kind of bearing with solid lubricant accelerated life test loading spectrum method for designing, it is characterised in that comprise the following steps: 1) obtain the operation on orbit section of bearing with solid lubricant；2) the loading spectrum block obtained is converted into loads typical spectrum block；3) according to failure mechanism and the Dynamic wear rule of bearing with solid lubricant, loading spectrum block is carried out staged care.On the premise of not changing bearing with solid lubricant failure mechanism, it is achieved the accelerated life test of bearing with solid lubricant has the purpose of preferable acceleration effect.

Description

A kind of bearing with solid lubricant accelerated life test loading spectrum method for designing

Technical field

The invention belongs to space flight spaceborne drive mechanism critical component reliability field, be specifically related to a kind of acquisition solid lubrication The method of bearing accelerated life test loading spectrum.

Background technology

Show according to external satellite statistics: " stuck " that spaceborne drive mechanism causes because of insufficient lubrication is to cause to defend The one of the main reasons that star lost efficacy, and the fretting wear of spaceborne drive mechanism is the major reason causing its hydraulic performance decline.Gu Body lubrication bearing is the critical component of spaceborne drive mechanism, and performance degradation and precision forfeiture that its long time running causes are impacts The key factor in satellite life-span in-orbit, thus its high reliability and long-life to the development of China's spacecraft and use to closing weight Want.Generally the life characteristics of product is to be obtained by the method doing life test under normal operation.But solid is moistened For plain besring, its design is accurate, weaving process is complicated, production cost is high, specificity is strong, typically will not carry out large batch of life Producing, the situation carrying out its Life cycle life test and relevant destructive life test is the most less.And along with design, manufacture The development of technology, and the use of new material, the life-span of space flight bearing with solid lubricant is more and more longer, so that life test Need to expend the longest test period and substantial amounts of testing expenses, it could even be possible to cause required test period to be far longer than Lead time, it is difficult to complete life appraisal and checking before being taken into use, thus the accelerated life test to bearing with solid lubricant Gradually it is subject to people's attention.

At present, at industrial quarters, electronic product stress accelerated life test method comparative maturity, perfect test is had to advise Model and statistical method can be followed, but the test sample amount needed is big, and test period is long.Engineering goods are because failure mechanism compares electricity Sub-product is increasingly complex, the most not yet forms standardized accelerated life test specification.Bearing with solid lubricant is as a kind of accurate Mechanical part, when its distinctive lubricating system, work, residing spatial environments and cyclic stress section determine its fault The characteristic that pattern is various, stress coupling is serious, causes traditional stress accelerated life test loading spectrum and existing acceleration Model is difficult to provide life appraisal result accurately.Therefore, the most deeply disclose the failure mechanism of bearing with solid lubricant, refinement adds Speed stress, how based on the distinctive failure mechanism of bearing with solid lubricant and working stress Section Design accelerated life test loading spectrum It is to break through the theoretical key with statistical method of bearing with solid lubricant accelerated life test.

Accelerated life test is on the premise of not changing product failure mechanism, by strengthening the way of stress, accelerates to produce Product fault, shortening test period, dope product method of life characteristics under normal stress effect in the short period of time.No Changing the premise that failure mechanism is accelerated life test, environmental stress or working stress that reinforcement product is born are by accelerating The necessary means of life test.Accelerated life test is to shorten test period by reinforcement stress, if but stress is excessive, changes Become the failure mechanism of product, then accelerated life test just loses meaning.If stress is less than normal, then test period can be caused to contract Short and inconspicuous, accelerated life test cannot obtain optimal effect.Accelerated life test loading spectrum i.e. refers at accelerated aging The stress strengthened in test and the relation corresponding to the relative time period.How the actual condition of bonded products, determines and does not changes Sell of one's property product failure mechanism and the accelerated life test loading spectrum always puzzlement designer of preferable acceleration can be played A difficult problem.

The reference material of external product accelerated life test can be retrieved at present, but have focused largely on grinding of statistical method Studying carefully, the content about loading spectrum design is considerably less.In view of abroad China's correlation technique being taked closing policy, we are to state's external-navigation How it bearing with solid lubricant designs accelerated life test loading spectrum is had no way of learning, China's accelerated aging to bearing with solid lubricant The research of test is the most at the early-stage, and up to the present not yet there is the bearing with solid lubricant accelerated aging being suitable for engineer applied in China Test load spectrum method for designing.

Summary of the invention

The present invention is to solve on the premise of not changing bearing with solid lubricant failure mechanism, it is achieved bearing with solid lubricant Accelerated life test has the purpose of preferable acceleration effect, proposes a kind of bearing with solid lubricant combined stress accelerated life test Loading spectrum method for designing, provides one for bearing with solid lubricant and does not change failure mechanism and acceleration effect the most significantly accelerates Life test loading spectrum method for designing, the method practicality and workable, is the row to bearing with solid lubricant life appraisal Effective accelerated method.

A kind of bearing with solid lubricant combined stress accelerated life test loading spectrum method for designing that the present invention proposes, specifically For:

Step one, the operation on orbit section of acquisition bearing with solid lubricant.

Operation on orbit section refers to that these parts have been a kind of working condition figure that aerial mission is drawn in-orbit, its horizontal seat Being designated as the time, vertical coordinate is loading stress corresponding to corresponding task and working condition.

Step 2, the loading spectrum block obtained is converted into loads typical spectrum block.

Loading spectrum be parts in real work, load subjected to stress, between the time used by working condition and every grade Corresponding relation.The such as axial load suffered by this example middle (center) bearing, the rotating speed of bearing and the corresponding relation between the persistent period.

Loads typical spectrum block is the most representative, can reflect the different grades of loading spectrum of practical working situation.

Step 3, according to the failure mechanism of bearing with solid lubricant and Dynamic wear rule, loading spectrum block is carried out at classification Reason.

Specifically, the present invention obtains above-mentioned purpose by subordinate's scheme.

A kind of bearing with solid lubricant accelerated life test loading spectrum method for designing, it is characterised in that comprise the following steps:

1) the operation on orbit section of bearing with solid lubricant is obtained；

2) the loading spectrum block obtained is converted into loads typical spectrum block；

3) according to failure mechanism and the Dynamic wear rule of bearing with solid lubricant, loading spectrum block is carried out staged care.

According to the method described in aforementioned schemes, it is characterised in that step 1) including: by analyzing in bearing with solid lubricant The abrasion of lubricating film and transfer, provide the pass of plated film wear rate and retainer lubriation material transfer rate and applied stress respectively System, obtains the abrasion of bearing with solid lubricant dynamic complex.

According to the method described in aforementioned schemes, it is characterised in that step 2) including: by directly intercepting the load that will obtain Lotus spectrum is converted into loads typical spectrum block.

According to the method described in aforementioned schemes, it is characterised in that step 3) including: retainer transfer rate is higher than Raceway groove plated film wear rate and cause the situation of lubricating film excess and/or retainer transfer rate less than raceway groove plated film wear rate And the loading spectrum block causing lubricating film to lack merges.

According to the method described in aforementioned schemes, it is characterised in that step 3) including:

The abrasion of bearing with solid lubricant dynamic complex obtains in the following way:

For raceway groove plated film rate of depreciation, introducing speed and the time characterizes sliding distance, obtaining wear extent formula is:

$W_1=K_1{p}_1^a{v}_1^b{t}^c---\left(1\right)$

Wherein W₁For raceway groove plated film wear extent, p₁For pressure, v₁For sliding speed, t is test period, K₁, a, b, c be all The constant determined based on statistical data；

The relation between raceway groove plated film wear rate and accelerated stress is simulated by statistical data；In view of solid lubrication The accelerated stress that bearing is conventional is rotating speed and axial load, and this relation is characterized as:

I_off=F₁(V,P) (2)

Wherein I_offRepresenting raceway groove plated film wear rate, V and P represents rotating speed and the amplitude of axial load stress respectively；

Polishing scratch based on retainer recessed in paraboloid shape, the expression formula of the frame lubricating film transfer amount that is maintained:

$W_2=K_2{p}_2^j{D}^m---\left(3\right)$

Wherein W₂For retainer lubricating film transfer amount, p₂For average Hertz contact force, D=v₂T is sliding distance, K₂、j、m For the constant determined based on statistical data, v₂For relative sliding velocity；Retainer lubriation material moves between speed and accelerated stress Relation be:

I_br=F₂(V,P) (4)

Wherein I_brRepresent retainer lubriation material transfer rate；

The lubricating film volume W of attrition on inside and outside raceway groove is obtained based on (2) formula and (4) formula_offT () and retainer are through rolling The lubricating film volume W of transfer on the outer raceway groove of kinetoplast_br(t), thus obtain the Expression of lubrication film thickness under different stress Formula:

$\mathrm{\δ}\left(t\right)={\mathrm{\δ}}_0+\frac{W_{br}\left(t\right)}{A}-\frac{W_{off}\left(t\right)}{A}---\left(5\right)$

Wherein δ is lubrication film thickness, δ₀For raceway groove plated film original depth, A is raceway groove plated film area.According to aforementioned schemes institute The method stated, it is characterised in that step 3) including:

The expression formula of described merging is:

${\mathrm{\Δ\δ}}_A=\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\Δ\δ}}_i---\left(6\right)$

Wherein N is the number of loading spectrum block, △ δ_iTotal lubricating film knots modification corresponding to i-th loading spectrum block, △ δ_A For the lubricating film knots modification that accelerating load spectrum block is corresponding.

Advantages of the present invention and having the active effect that

(1) in the case of conventional life test loading spectrum determines, it is possible to accelerating solid lubrication bearing event largely Barrier process, accelerates to obtain the speed of Test to Failure sample；

(2) provide based on spectrum block-grading and the loading spectrum method for designing of equivalent damage, it is possible to preferably reflection solid profit The actual motion load section of plain besring；

(3) when designing bearing with solid lubricant accelerated life test loading spectrum, by adjusting amplitude and the time of stress, protect Card does not change the failure mechanism of bearing with solid lubricant.

Accompanying drawing explanation

Fig. 1 is structure and the lubricating film transfer schematic diagram of bearing with solid lubricant；

Fig. 2 is bearing with solid lubricant accelerated life test loading spectrum method for designing；

Fig. 3 is the derivation of bearing with solid lubricant dynamic complex wear law；

Fig. 4 is the Elliptical Contacts region of rolling element and raceway groove.

Wherein accompanying drawing is to schematically illustrate present disclosure, not uses content shown in the drawings to the present invention Content specifically limit.

Detailed description of the invention

Below in conjunction with the accompanying drawings and the embodiment bearing with solid lubricant accelerated life test loading spectrum design side to the present invention Method is described in detail.

Fig. 1 is the schematic diagram of bearing with solid lubricant, and bearing with solid lubricant generally uses bearing internal external circle, retainer and rolling The version that body combines.Wherein 1 is outer ring, and 2 is inner ring, and 3 is retainer, and 4 is the outer ring lubricating film on outer ring 1, and 5 is interior Inner ring lubricating film on circle 2,6 is rolling element.Outer ring is held generally stationary, and inner ring generally rotates with the axis, in actual application two The movement relation of person can also need to change, and i.e. can fix by inner ring 2, and outer ring 1 rotates.Between inner ring 1 and outer ring 2 When there is relative motion, rolling element 6 rotates.Outer ring lubricating film 4 is positioned in the raceway groove on the inner surface of outer ring 1, and inner ring lubricating film 5 is then It is positioned in the raceway groove on inner ring 2 outer surface.The most popular material of lubricating film is molybdenum bisuphide.Lubricating film can use plated film Mode prepare.Retainer 3 is the retainer of a kind of self-lubricating function, is made up, most frequently of " expendable " lubriation material The material used is PI (polyimides) and MoS₂.In bearing with solid lubricant operation process, raceway groove plated film plays lubrication；And Retainer is then designed to controlled speed and mode and transfers on inside and outside raceway groove through rolling element rotation by the lubriation material of self, Play the effect that the loss to lubricating film supplements, to keep lubricant effect.

As in figure 2 it is shown, the method being accelerated the design of life test loading spectrum is as follows:

Step one, the operation on orbit section of acquisition bearing with solid lubricant.At start of run, play the mainly ditch of lubrication Road plated film.Along with contacting and mutually collision of the rotation of rolling element and rolling element and retainer, the lubriation material of retainer leads to The rotation crossing rolling element is constantly shifted on raceway groove, and in the process, raceway groove plated film gradually wears out and consumes, and raceway groove plated film is gradually Transition is transfer lubrication, and final transfer membrane plays primary lubricant effect, as shown in Figure 1.All consume to raceway groove plated film and transfer membrane After, bearing gradually wears out until losing efficacy.During real-world operation, it is also possible to the feelings that lubriation material transfer velocity is too fast occur Condition, causes lubriation material to be piled up on inside and outside raceway groove.Cause moment of friction excessive, make bearing stall or be difficult to smooth working, entering And cause losing efficacy.Accordingly, it would be desirable to the abrasion of lubricating film and metastatic rule in further investigation bearing with solid lubricant, provide plated film respectively Wear rate and retainer lubriation material transfer rate and the relation of applied stress, obtain bearing with solid lubricant dynamic complex abrasion rule Rule, in order to the design of follow-up accelerated life test loading spectrum.

The derivation of bearing with solid lubricant dynamic complex wear law is as shown in Figure 3.For raceway groove plated film rate of depreciation, Introducing speed and the time characterizes sliding distance, obtaining wear extent formula is:

$W_1=K_1{p}_1^a{v}_1^b{t}^c---\left(7\right)$

Wherein W₁For raceway groove plated film wear extent, p₁For pressure, v₁For sliding speed, t is test period, K₁, a, b, c be all The constant determined based on statistical data.

Rolling element belongs to point cantact with contacting of inside and outside raceway groove.According to Hertz contact theory, can by force analysis and The external load (i.e. accelerated stress) applied obtains the stress distribution of contact area.Again based on macroscopic view theory of wear, can pass through Statistical data simulates the relation between raceway groove plated film wear rate and accelerated stress.In view of conventional the adding of bearing with solid lubricant Speed stress is rotating speed and axial load, and this relation can be characterized as:

I_off=F₁(V,P) (8)

Wherein I_offRepresenting raceway groove plated film wear rate, V and P represents rotating speed and the amplitude of axial load stress respectively.

The transfer rate of retainer lubriation material equally obtains based on tribology method.Polishing scratch based on retainer Recessed in paraboloid shape, provide the expression formula of retainer lubricating film transfer amount:

$W_2=K_2{p}_2^j{D}^m---\left(9\right)$

Wherein W₂For retainer lubricating film transfer amount, p₂For average Hertz contact force, D=v₂T is sliding distance, K₂、j、m For the constant determined based on statistical data, v₂For relative sliding velocity.It is equally based on macroscopic view theory of wear and contacts reason with Hertz Opinion.Utilizing the methods such as finite element analysis, can be maintained the relation between frame lubriation material transfer rate and accelerated stress, table Levy for:

I_br=F₂(V,P) (10)

Wherein I_brRepresent retainer lubriation material transfer rate.In conjunction with actual load history, can be divided into based on (8) formula (10) formula is calculated the lubricating film volume W of attrition on inside and outside raceway groove_offT () and retainer are through the inside outer fissure of rolling element The lubricating film volume W of transfer on road_br(t), and then the Expression formula of lubrication film thickness under different stress can be given:

$\mathrm{\δ}\left(t\right)={\mathrm{\δ}}_0+\frac{W_{br}\left(t\right)}{A}-\frac{W_{off}\left(t\right)}{A}---\left(11\right)$

Wherein δ is lubrication film thickness, δ₀For raceway groove plated film original depth, A is raceway groove plated film area.Above-mentioned lubrication film thickness Expression formula i.e. characterize bearing with solid lubricant dynamic complex abrasion.According to Dynamic wear rule and obtain based on statistical data Fault threshold can obtain physical essence and the coupled relation of bearing with solid lubricant failure mechanism under different stress level, for it The design of accelerated life test loading spectrum lays the foundation.

Step 2, the loading spectrum block obtained is converted into loads typical spectrum block.Because the acceleration that bearing with solid lubricant is conventional Stress has two rotating speeds and axial load, and the bearing with solid lubricant that reality is in-orbit may bear increasingly complex stage Loading spectrum, so, by directly intercepting, the loading spectrum obtained can be converted into loads typical spectrum block.

Step 3, according to the failure mechanism of bearing with solid lubricant and Dynamic wear rule, loading spectrum block is divided into level Four, I Level represents that retainer transfer rate is too fast, and under this kind of stress level, bearing with solid lubricant will quickly be formed on inside and outside raceway groove Amount lubricating film, causes stall to be quickly invalidated.This kind of loading spectrum block typically will not occur in engineering reality, or in whole load Ratio shared in lotus spectrum is the least, but can quickly cause bearing fault, thus belongs to the loading spectrum block changing failure mechanism, Reservation is should give during loading spectrum establishment.II level represents that retainer transfer rate is higher than raceway groove plated film wear rate, but will not be short Cause lubricating film excess in time, engineering reality is often reflected as moment of friction bigger than normal, cause after extended periods losing efficacy. III level represents that retainer transfer rate is less than raceway groove plated film wear rate, thus bearing can progressively consume raceway groove plated film and transfer Film, finally causes losing efficacy because of lubricating film disappearance.IV level represents retainer transfer rate and raceway groove plated film wear rate the most very Slowly, in such cases, bearing lubrication film thickness is kept approximately constant, thus this type of loading spectrum block performance to bearing with solid lubricant Degenerate and the impact in life-span almost can be ignored；For bearing with solid lubricant in orbit, this type of load occupies significant proportion, Generally can omit when loading spectrum is worked out.

To above II level and III level loading spectrum block, generally use the shape of merging when working out accelerated life test loading spectrum Formula.For bearing with solid lubricant, the principle of merging is equivalent damage principle (i.e. equivalence lubrication film thickness knots modification).II level carries What lotus spectrum block was corresponding is transfer membrane excess fault, and corresponding lubrication film thickness increases, and its combination principle is:

${\mathrm{\Δ\δ}}_A=\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\Δ\δ}}_i---\left(12\right)$

Wherein N is the number of II level loading spectrum block, △ δ_iTotal lubricating film corresponding to i-th II level loading spectrum block changes Variable, △ δ_AFor the lubricating film knots modification that accelerating load spectrum block is corresponding.According to calculated △ δ_A, can adopt based on formula (11) Calculate the value of accelerated stress V and P with optimization method, also need during practical operation to consider engineering realizability.

What III level loading spectrum block was corresponding is lubricating film miss fault, and corresponding lubrication film thickness reduces, combination principle and II level Loading spectrum block is identical.

Example:

Use the inventive method as follows to the design of certain spaceborne bearing with solid lubricant accelerated life test loading spectrum:

First the working environment analyzing bearing with solid lubricant and the stress born, and carry out the selection of accelerated stress.Gu Body lubrication bearing is a kind of spaceborne transmission component of basic space flight, is widely used in each quasi-instrument and the mechanism of spacecraft. The environmental stress that bearing with solid lubricant bears mainly has temperature, radiation etc., and working stress mainly has rotating speed, radial load, axially Load etc..

In real work, how bearing with solid lubricant is caused by insufficient lubrication or abrasion if losing efficacy.Solid lubricant film gradually wears out Consume, destruction of lubricating film and cause bearing moment increase or vibration increase, ultimately result in inefficacy.Carry out bearing with solid lubricant acceleration During life test, main selection rotating speed and axial load are as accelerated stress.

Table 1 gives certain spaceborne bearing with solid lubricant load history in-orbit, and experience total time in each cycle is 11min. Load history shown in table 1 is divided into 6 stages, and the most corresponding corresponding operating mode, i.e. low speed in-orbit rotate forward, low-speed reverse rotation Turn, high-speed forward rotation, the stage such as high-speed reverse rotation.Because the accelerated stress that bearing with solid lubricant is conventional has two, will To loading spectrum block be converted into loads typical spectrum block.Failure mechanism according to bearing with solid lubricant and Dynamic wear rule are permissible Its loading spectrum block being divided into level Four, wherein can be intercepted in the 1-5 stage in table 1 and compose block for II level and III level, the 6th stage was I level spectrum Block.

Certain spaceborne bearing with solid lubricant load history in-orbit of table 1

Spacecraft mechanism bearing with solid lubricant is generally operational under underloading speed operation.And for rolling body bearing, often execute Add certain axial pretightening load to improve rigidity and the running accuracy of bearing.Calculate for simplifying the analysis, do following two herein Point is assumed:

1) under speed operation, the produced inertial load of rolling element motion is ignored.

2) under space microgravity environment, rolling body bearing is subjected only to prefastening load.

When bearing bears central axial prefastening load Fa, the contact load Q of each rolling element is identical, i.e.

$Q=\frac{P}{Zsin\mathrm{\α}}---\left(13\right)$

In formula, Z is the number of rolling element, and α is bearing the actual contact angle.Theoretical according to point cantact Hertz, according to point cantact Hertz theory, the contact area of rolling element and inside and outside raceway groove is oval.Set up coordinate system s={o, x y z}, the initial point o of coordinate system s Being located at elliptical center, x-axis is along transverse direction, and y-axis points to the rotating direction of rolling element along ellipse short shaft, and z-axis is along contact surface Normal direction, as shown in Figure 4, elliptical contact any point (x, y) contact force at place is:

$p(x,y)=p_0\sqrt{1-{\left(\frac{x}{a}\right)}^2-{\left(\frac{y}{b}\right)}^2}---\left(14\right)$

In formula, p₀For the Max.contact stress of elliptical contact, a, b are respectively oval long and short semiaxis according to maximum The computing formula of Hertz contact stress, obtaining its Max.contact stress is:

$p_0=\frac{1.5}{{\mathrm{\πe}}_a{e}_b{\mathrm{\ϵ}}_E^2}\sqrt[3]{{\mathrm{\Σ\ρ}}^2}Q---\left(15\right)$

π e in formula_ae_bFor constant, Hertz contact coefficient table can be looked into and obtain, ∑ ρ²For contact object principal curvatures and, this In take ε_E=1.

The motion analysis following several presupposition of introducing to rolling body bearing:

1) bearing outer ring is fixed, inner ring rotates；

2) under speed operation, the contact angle of bearing internal external circle is identical, and does not consider the gyration of rolling element；

3) rolling element only rolls at bearing outer ring channel, and has spin in the existing rolling of bear inner ring grooved railway.

4) (x, y) (x is y) along ellipse at this to the relative sliding velocity v of place's rolling element and bear inner ring grooved railway to elliptical contact point (x, y) (x, vector y) are shown in Fig. 4 to the differential sliding speed v 1 of circle short-axis direction with revolving sliding speed v 2.

Point (x, y) place's sliding speed v (x, y) be:

$v(x,y)=\sqrt{v_1^2+v_2^2-2v_1{v}_{2}cos(\mathrm{\π}-\mathrm{\φ})}=g(x,y)\mathrm{\ω}---\left(16\right)$

In formula, ω is the absolute angular velocities that bearing inner race rotates；(x, y) is elliptical contact x to g, the function of y, with bearing Geometrical property, operating mode (load) etc. are relevant.

From formula (7), rolling element and any point (x, y) the line wear rate of place's solid lubricant film in raceway groove elliptical contact For:

$\mathrm{\γ}(x,y)=K_1{p}_1^a{v}_1^b---\left(17\right)$

As shown in Figure 4, at point, (x, y) place takes minute area unit dxdy.From formula (4), each rolling element and ditch stage property Having identical contact, by γ, (x, y) is integrated in elliptical contact, can obtain the abrasion of bearing inner race raceway groove solid lubrication membrane volume Rate w is:

$w_1=Z\underset{\mathrm{\Ω}}{\∫\∫}\mathrm{\γ}(x,y)dxdy={\mathrm{ZK}}_1\underset{\mathrm{\Ω}}{\∫\∫}{p}^a{v}^{b}xdy---\left(18\right)$

In formula, Ω is the elliptical contact of rolling element and bearing inner race raceway groove.Formula (14), (16) are substituted into formula (18) and obtain Arrive:

$w_1=Z\underset{\mathrm{\Ω}}{\∫\∫}\mathrm{\γ}(x,y)dxdy={\mathrm{ZK}}_1\underset{\mathrm{\Ω}}{\∫\∫}{p}^a{v}^{b}xdy={\mathrm{ZK}}_1{p}_0^a{\mathrm{\ω}}^b\underset{\mathrm{\Ω}}{\∫\∫}{\left(\sqrt{1-{\left(\frac{x}{a_i}\right)}^2-{\left(\frac{y}{b_i}\right)}^2}\right)}^a{g}^{b}dxdy---\left(19\right)$

A in formula_i, b_iIt is respectively rolling element and the semi-major axis of bearing inner race raceway groove elliptical contact and semi-minor axis, subscript i table Show inner ring.

Order

$K_3=Z\underset{\mathrm{\Ω}}{\∫\∫}{\left(\sqrt{1-{\left(\frac{x}{a_i}\right)}^2-{\left(\frac{y}{b_i}\right)}^2}\right)}^a{g}^{b}dxdy---\left(20\right)$

Parameter K₃Relevant with elliptical contact shape, bearing operating mode and bearing geometrical property etc..

Now, formula (19) is represented by:

$W_1=K_1{K}_3{p}_0^a{\mathrm{\ω}}^{b}t---\left(21\right)$

At stable wear stage it is believed that the Volume erosion rate w of solid lubricant film₁Keep constant in time.Now, formula (7) In parameter c=1, take K=K₁K₃=4.0 × 10^-9.Bearing with solid lubricant wear out failure model under checking vacuum environment, needs Obtain testing data of life-span under vacuum environment, and obtain corresponding parameter K according to the testing data of life-span under vacuum environment₁、K₃、 The numerical values recited of a, b, owing to experiment condition is limited, the working condition of actual bearing with solid lubricant in-orbit is complex, it is impossible to Ground obtains its accurate numerical values recited, according to statistical data, takes a=0.127, b=1.3849.In like manner, can be in the hope of retainer Lubricating film transfer amount is represented by:

$W_2=K_2{p}_2^j{D}^m---\left(22\right)$

Ibid, K is taken₂=1.2 × 10^-8, j=0.103, m=1 then can be in the hope of:

In the loading spectrum block of corresponding II level and III level, the knots modification of the lubricating film of i-th spectrum block is:

δ_i=W₁-W₂ (23)

First five stage of table 1 correspondence is intercepted and composes block for II level and III level,

Certain first five stage of spaceborne bearing with solid lubricant of table 2 intercepts

Therefore can be obtained by above formula (21) (22) (23):

δ₁=2.5069 × 10^-5-3.0930×10^-5=-5.8610 × 10^-6

δ₃=4.4105 × 10^-5-3.1727×10^-5=1.2379 × 10^-5

δ₅=0.0011-5.9539 × 10^-4=4.5549 × 10^-4

${\mathrm{\Δ\δ}}_A=\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\Δ\δ}}_i=4.6853\×{10}^{-4}$

According on the premise of not changing bearing with solid lubricant failure mechanism, according to actual condition, II and III level are composed block Merging so that it is having acceleration effect as well as possible, here we take axial load 20N, rotating speed 240rpm merges as it Rear operating mode, then try to achieve the acceleration time according to formula (11) (21) (22):

T=253.5394s=4.2257min

The time in one cycle of experience can be equivalent to 5.2257min.Finally, the constant stress life testing spectrum of bearing with solid lubricant As table 3 is shown as:

Certain spaceborne bearing with solid lubricant constant stress life testing spectrum of table 3

By above-mentioned accelerated life test loading spectrum translation method, bearing with solid lubricant failure mechanism can not changed Under premise, utilize the typical condition taked, the bearing with solid lubricant in six stages originally load history in-orbit is equivalent to State two typical stages, the total time used by each of which cycle be also reduced to 5.2257min by original 11min, added quick-acting Fruit is the most obvious, it is possible to the crashed process of accelerating solid lubrication bearing largely, thus obtains and effectively accelerate the longevity Life test load spectrum.

Obviously, above-described embodiment is only for clearly demonstrating example of the present invention, and not to the present invention The restriction of embodiment.For those of ordinary skill in the field, can also be made it on the basis of the above description The change of its multi-form or variation.Here without also cannot all of embodiment be given exhaustive.And these belong to this What bright spirit was extended out obviously changes or changes among still in protection scope of the present invention.

Claims (6)

1. a bearing with solid lubricant accelerated life test loading spectrum method for designing, it is characterised in that comprise the following steps:

1) the operation on orbit section of bearing with solid lubricant is obtained；

2) the loading spectrum block obtained is converted into loads typical spectrum block；

3) according to failure mechanism and the Dynamic wear rule of bearing with solid lubricant, loading spectrum block is carried out staged care.

Method the most according to claim 1, it is characterised in that step 1) including:

By analyzing abrasion and the transfer of lubricating film in bearing with solid lubricant, provide plated film wear rate and retainer lubrication material respectively Material transfer rate and the relation of applied stress, obtain the abrasion of bearing with solid lubricant dynamic complex.

Method the most according to claim 1, it is characterised in that step 2) including:

By directly intercepting, the loading spectrum obtained is converted into loads typical spectrum block.

Method the most according to claim 1, it is characterised in that step 3) including:

For retainer transfer rate higher than raceway groove plated film wear rate and cause lubricating film excess in the case of and/or retainer turn The loading spectrum block that shifting speed causes lubricating film to lack less than raceway groove plated film wear rate merges.

Method the most according to claim 2, it is characterised in that step 3) including:

The abrasion of bearing with solid lubricant dynamic complex obtains in the following way:

For raceway groove plated film rate of depreciation, introducing speed and the time characterizes sliding distance, obtaining wear extent formula is:

$W_1=K_1{p}_1^a{v}_1^b{t}^c---\left(1\right)$

Wherein W₁For raceway groove plated film wear extent, p₁For pressure, v₁For sliding speed, t is test period, K₁, a, b, c be all based on system Count the constant determined；

The relation between raceway groove plated film wear rate and accelerated stress is simulated by statistical data；In view of bearing with solid lubricant Conventional accelerated stress is rotating speed and axial load, and this relation is characterized as:

I_off=F₁(V,P) (2)

Wherein I_offRepresenting raceway groove plated film wear rate, V and P represents rotating speed and the amplitude of axial load stress respectively；

Polishing scratch based on retainer recessed in paraboloid shape, the expression formula of the frame lubricating film transfer amount that is maintained:

$W_2=K_2{p}_2^j{D}^m---\left(3\right)$

Wherein W₂For retainer lubricating film transfer amount, p₂For average Hertz contact force, D=v₂T is sliding distance, K₂, j, m be base In the constant that statistical data determines, v₂For relative sliding velocity；

Relation between retainer lubriation material transfer rate and accelerated stress is:

I_br=F₂(V,P) (4)

Wherein I_brRepresent retainer lubriation material transfer rate；

The lubricating film volume W of attrition on inside and outside raceway groove is obtained based on (2) formula and (4) formula_offT () and retainer are through rolling element The inwardly lubricating film volume W of transfer on outer raceway groove_br(t), thus obtain the Expression formula of lubrication film thickness under different stress:

$\mathrm{\δ}\left(t\right)={\mathrm{\δ}}_0+\frac{W_{br}\left(t\right)}{A}-\frac{W_{off}\left(t\right)}{A}---\left(5\right)$

Wherein δ is lubrication film thickness, δ₀For raceway groove plated film original depth, A is raceway groove plated film area.

Method the most according to claim 4, it is characterised in that step 3) including:

The expression formula of described merging is:

${\mathrm{\Δ\δ}}_A=\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\Δ\δ}}_i---\left(6\right)$

Wherein N is the number of loading spectrum block, △ δ_iTotal lubricating film knots modification corresponding to i-th loading spectrum block, △ δ_AFor adding The lubricating film knots modification that speed loading spectrum block is corresponding.