preload preload preload preload

The comprehensive diagnostic technique of use carries on condition monitoring to the bearing of the high-speed electric machine


31st May 2013 Bearing Technology 0 Comments

Summary: Carry on the condition monitoring means to the rotatory apparatus at present, use more general method to mainly have vibration analysis and fluid analysis. Under the a lot of situation, it uses simplex analysis to be means very difficult to make a definite diagnosis of placement and severity of trouble that trouble take place, the most valid means is that many kinds of analytical techniques of comprehensive utilization will come to monitor it at this time. The article, through shaking and abrading analytic comprehensive diagnosis, the trouble that the electrical machinery bearing predicting accurately the blast furnace takes off the silicon dusting air blower exists, further explain the comprehensive diagnostic necessity.

Keyword: Vibration analysis Ferrography of spectral analysis Antifriction bearing Condition monitoring

In the metallurgical industry, use various equipment configurations in a large amount, its operational capacities depends on equipment capacity to a great extent. If can reduce the equipment failure, raise the utilization of capacity of the apparatus by 10%, mean that improves 10% of the operational capacities without equipment investment, so, improve the reliability of different apparatuses to realizing the continuous running of the apparatus has already become indispensable. In addition, through improving and stability quality and lengthening the life time of the apparatus, it is higher and higher by realizing and reducing the requirement of the maintenance cost.

The system of maintenance equipment is maintained, taking time as basic reference and maintained Time Based Maintenance is abbreviated as TBM after going through And the maintenance Condition Based Maintenance is abbreviated as CBM taking state as basic reference Three stages. TBM because it is the unconditional scheduled maintenance, the problem of excessive maintenance exists, will contribute to the losses that unnecessarily. And CBM is through diagnosing the equipment state, implements maintenance equipment according to the diagnostic result, it is the optimal maintenance method. The precondition of implementation is that a diagnostic result to the equipment state should be accurate and reliable if CBM can be effective. Carry on the condition monitoring means at present, use more general method to mainly have vibration analysis and fluid analysis. Vibration analysis is that the signal through pairing vibration one is dealt with to judge the abrasion state of the apparatus, it can diagnose cranky type and placement, but is influenced by working condition condition greater. The fluid is analyzed to be to abrading the particle to carry on quantification and qualitative analysis in lubricant with spectrum and iron table analytical technique, thus diagnose cranky type and placement, its analysis result is influenced by working condition terms minorly, mainly suitable for low speed, heavily loaded and the trouble develops the slower apparatus. Under the most situation, it uses simplex analysis to be means very difficult to make a definite diagnosis of placement and severity of trouble that trouble take place, the most valid means is monitored on lying in many kinds of analytical techniques of comprehensive utilization come it at this time.

It is a high-speed rotation apparatus to take off the silicon dusting air blower, belong to the important apparatus on the production line of steel-making, if break down, influence the normal operation of the blast furnace directly and and will cause the huge economic loss, so have important meanings to hold the working condition of the bearing of the electrical machinery. Since this apparatus included in controlledly monitoring in January of 2001, the vibration value of this aircrew has been in more steady state all the time. Will it be October 22 2002, vibration test analyze indicate two electrical machinery vibration value of side bearing increase phenomena, suspect the bearing is unusually abraded and presented. Have transitivity because of the unusual vibration between apoplexy machine, shaft coupling and electrical machinery of the aircrew, may influence each other between the three, so, in order to further confirm the wear degree of placement and bearing breaking down, still take a sample and carry on spectrum and iron spectral analysis to the grease of the side bearing of the electrical machinery two. About grease spectrum and iron table analytical method, can consult relevant literature [1- 5 ], no longer go into details here.

A basic parameter

Bearing type: The load side of electrical machinery: SKF NU234 EcMa/C3; The free-side of electrical machinery: SKF NU23OEC3.

Bearing material: , outer lane in the bearing: Bearing steel, its alloying element is with chromium Cr And manganese Mn It is a main fact. Rolling element: The alloy steel of high chromium, hardness HRC60-64. Retainer: Brass.

Lubricating method: The lubrication of the side bearing of the electrical machinery two adopts 2 #s to press lithium saponify to lubricate very much.

Tester: The used instrument of vibration test is: MCV- 021 ride meter which Japan produces, SONY PC208AX magnetic tape unit, CF- 920 spectrum analyzer. Abrade to test the adoption instrument is: Pair analysis mode ferrogram machine which U.S.A. Standard Oil Company produces, RPD rotary ferrogram machine and Japan Olympus BX60 iron table microscope which Predict Company produces.

The state of taking a sample explains: Take off the silicon dusting air blower synoptic diagram and is shown as in Fig. 1. 1, 2 is the antifriction bearing in the picture, 3, 4 is the sliding bearing. Before taking a sample to the bearing grease of electrical machinery, it is removed that the already polluted grease of outside of oil hole will appear first, and then gather the oil sample by way of adding the new grease and squeezing out the grease in the bearing, about 100 grams of taking a sample amount.

Fig. 1 takes off the silicon dusting air blower synoptic diagram

The bearing trouble frequency: The following are trouble frequency formulae of the load side bearing of electrical machineries:

Outer lane: 7.66667* f electrical machinery

Inner circle: 10.3333* f electrical machinery

Friction roller: 3.30093* f electrical machinery

Retainer: 0.425926* f electrical machinery

Among them f electrical machinery is the frequency of motor speed.

2 results and discussing

2.1 Vibration analysis

This apparatus includes in controlledly monitoring, its shaking value has been in more stable state all the time, the mean value of vibration velocity, generally about 0.5 mm s-1, the vibration acceleration is generally under 1.0 m s-2 on the both sides pedestal of the electrical machinery. Will it be October 22 2002, vibration test analyze indicate the intersection of electrical machinery and the intersection of load and vibration value of side bearing increase phenomena see Table 1 ,Especially vertical and horizontal vibration acceleration and bearing impact value increase obviously, suspect the bearing is unusually abraded and presented. Then monitor tracing to it again on November 5.

2.1.1 Shake value analysis

The normal state of the apparatus ‘ August 8, 2002 Down with the abnormal state ‘ November 5, 2002 Leave the shaking value to compare, can find:

Vibration velocity value: Besides shaking and increasing among the axles on the load side pedestal of the electrical machinery, the vibration value of its level and vertical direction is basically about equal.

Vibration acceleration value: The vibration acceleration value in every measuring point direction has increase at various degrees on the load side pedestal of the electrical machinery, among them the value average of the vibration acceleration of the vertical direction increases from 0.40 m s-2 to 5.19 m s-2, it is 13.0 fold, the crest value rises to 34.6 from 1.9, has increased by 17.2 times, and mean value of acceleration and crest value in the horizontal direction have increased by 7.7 times and 8.2 times respectively, axial acceleration average and crest value have increased by 1.9 times and 1.8 times respectively.

Vibration test data of the electrical machinery load side bearing of Table 1

Note: A- represents axial; V- represents the vertical direction; H- represents the horizontal direction

Bearing impact value: Also the situation similar to vibration acceleration, among them the mean value in the vertical direction increases from 0.29 to 4.98, it is 17.2 fold, the crest value rises to 16.3 from 0.9, has increased by 17.1 times, and mean value and crest value in the horizontal direction have increased by 13.8 times and 15.8 times respectively, axial mean value and crest value have increased by 13.3 times and 15.5 times respectively.

Comparing the analytical data on October 22 with data on November 5 again can be found, the vibration acceleration of the vertical direction value is improved from 2.80 m s-2 to 5.19 m s-2, but the bearing impact value increases from 1.89 to 4.98, having increased by 0.9 times and 1.6 times separately, and vibration acceleration value and bearing impact value in the horizontal direction have increased by 0.4 times and 2.1 times respectively, quite explain unusually attrited development fast.

The above-mentioned analysis show, though it is more difficult to find the existence of the trouble from the vibration velocity value, but can find plain this bearing is unusually abraded and presented from the change of bearing impact value and vibration acceleration.

Shake sugnak analysis on 2.1.2

Spectral signal of axial vibration velocity of side bearing of the electrical machinery load of Fig. 2

Analyze on the spectral signal of the axial vibration velocity of the load side pedestal of the electrical machinery as follows. Knowing by Fig. 2:

On the time domain, exist for more obvious cycle and assault, the interval is Δ t =133.5 Ms and Δ t =60.5 Ms, gets Δ f =7.5Hz and Δ f =16.53Hz, among them f =7.5Hz is the trouble frequency of the bearing retainer, and f =16.53Hz is the frequency of rotational speed of the electrical machinery.

On the frequency domain, by f =7.5Hz and harmonic frequency, f =128.75Hz is the primary frequency, Δ f of side frequency =7.5Hz makes up. Among them f =128.75Hz is the trouble frequency of outer lane of the bearing. Also there is f on frequency spectrum =158.75Hz, it is f =Sum of 128.75Hz and 4* 7.5Hz side frequency.

The above-mentioned analysis indicate, the bearing retainer has more obvious unusual abrasion, the bearing outer lane has unusual abrasion signs too.

2.2 Abrade and analyze

Process it into liquid solution in advance by way of adding the special solvent in the grease at first, then spectrum and iron table analytical method that can draw lessons from the lubricating oil carry on quantification and qualitative analysis to it.

2.2.1 Spectral analysis

The metal composition of abrasion from the knowing grease of material of the bearing is mainly iron and copper element, so mainly consider the content here in the grease of these two kinds of elements. Knowing by Table 2, mainly contain copper element in the grease of the load side bearing, its content is 14.0 times that of free side bearing lubricating grease, it comes from the abrasion of the bearing retainer; The element density of iron is 3.1 times that of free-side. Therefore can judge that unusually abrade the load side bearing that comes from the electrical machinery.

The spectral analysis data unit of Table 2: μ g/g

2.2.2 Iron spectral analysis

The iron spectral analysis of the load side bearing reveals that there is a large amount of larger copper alloy abrasive grain in the grease, maximum sizes are more than 200 microns, other jumbo size are 140* 80, 100* 60, 80* 60 microns,etc., its kind has slice, slips the abrasive grain see Fig. 3 massively and seriously . In addition more ferromagnetic abrasive grain exist, the kind slips the abrasive grain, slice, cuts the form, globoid abrasive grain etc. normally, among them the size of the flaky abrasive grain is 100* 60, 80* 30, 60* 40 microns,etc.; The maximum size of cutting the abrasive grain of form is 120* 3 micron See Fig. 4 .

The iron spectral analysis of the freedom side bearing finds that though copper alloy and steel abrasive grain have appeared in the grease too, but it is small in quantity, and the size is small.

Obtain the diagnostic result in view of the above: The load side bearing exists and unusually abrades more seriously, the main source of the trouble lies in the abrasion of the bearing retainer.

The copper alloy abrasive grain picture 4 of Fig. 3 cuts the steel abrasive grain of form

2.3 Diagnosis and suggestion

Synthesize the above analysis result shaken and abraded, can draw the following conclusion: The load side bearing of the electrical machinery exists and obviously unusually abrades, among them the abrasion of the retainer is quite serious, and unusually abrade the excessive growth. Advise the factory to shut down and overhaul the bearing immediately in view of the above.

2.4 Overhaul the result

November 7, factory go on, dismantle, examine to it, find electrical machinery load retainer of side bearing two end grind off into depth of 2-4 mm axially, leave an obvious step, and have obvious strip impressions on the inner cycle sum outer lane of the bearing, rubing the mark on the friction roller is very obvious too.

After changing the side bearing of the electrical machinery two, have tested the situation of the monosomatous runtime of the electrical machinery again, compared with data examined in the front, its shaking value obviously drops. Several following analysis shows too, the vibration of this aircrew has already been returned to the normal level.

3 conclusions

The integrated application of many kinds of analytical methods through shaking, abrading,etc., the trouble that the electrical machinery bearing that we have predicted the blast furnace takes off the silicon dusting air blower in time exists, especially in fixing location accurately to bearing trouble, to overhauling and playing very important guidance function, and resumed production rapidly for the removal of faults as soon as possibling plays an essential role, the diagnostic meaning is embodied at this point.

In a word, the integrated application of many kinds of analytical methods is to improving the diagnostic rate of accuracy of the trouble and guaranteeing the normal operation of the mechanical equipment is very essential finally, this will be diagnostic developing direction of the trouble in the future.

Bibliographical reference

D.P. Andersen arranges, the gold dollar is grown, Yang QiMing translates. Atlas of abrasive grain. Beijing: The publishing house of the mechanical industry, 1987: 79-81

2 desolate Chinese roof beams. Ferrography and monitoring the application in diagnosing in machinery. Beijing: People’s Transportation Press, 1993,202-206

3 masses troops Kui,etc.. Grease iron spectral analysis. Lubricate and seal. 1998 4 : 33

4 benevolent moral integrity Liu,etc.. Analytic study and application of iron table of grease. Lubricate and seal. 2002 5 : 65-66

5 benevolent moral integrity Liu,etc.. Application of ferrography in the condition monitoring of the lubricated antifriction bearing of lipoprotein. Chinese Mechanical Engineering Society can rub credit lubricated the intersection of technology and professional the intersection of committee and academic annual meeting on the eighth ‘ Xiamen Collection of thesis. 2002: 142-145

6 pottery Germany and China,etc.. Use spectrum and iron table analytical technique lubricate and move the bearing and carry on condition monitoring to the lipoprotein. The 11th Chinese apparatus is monitored and diagnose the collection of thesis of the academic meeting. October of 2002, Wuxi, 327~329 end










  • Leave a Reply

    * Required
    ** Your Email is never shared