轴承损坏及检测.pdf

Rolling Bearing Damage Recognition of damage and bearing inspection A Member of the Schaeffler Group Rolling Bearing Damage Recognition of damage and bearing inspection Publ. No. WL 82 102/2 EA 标准分享网 w w w .b z f x w .c o m 免费下载 Preface Rolling bearings are machine elements found in a wide field of applications. They are reliable even under the toughest con- ditions and premature failure is very rare. The first sign of rolling bearing damage is primarily un- usual operating behaviour of the bearings. The examination of damaged bearings reveals a wide and varied range of phenome- na. Inspection of the bearings alone is normally not enough to pinpoint the cause of damage, but rather the inspection of the mating parts, lubrication, and sealing as well as the operating and environmental conditions. A set procedure for examina- tion facilitates the determination of the cause of failure. This brochure is essentially a workshop manual. It provides a survey of typical bearing damage, its cause and remedial measures. Along with the examples of damage patterns the possibility of recognising the bearing damage at an early stage are also presented at the start. Bearings which are not classified as damaged are also in- spected within the scope of preventive maintenance which is frequently carried out. This brochure therefore contains examples of bearings with the running features common to the life in question. Cover page What may at first appear to be a photo of sand dunes taken at a high altitude is in fact the wave-shaped defor- mation-wear-profile of a cylindrical roller thrust bearing. There is less than just 1 micron from peak to valley. At a slow speed mixed friction occurs in the areas stressed by sliding contact. Rippling results from the stick-slip effects. FAG2 Contents 1Unusual operating behaviour indicating damage . . . . . . . . . . . . . . . . . . . . . . . . . . .4 1.1Subjective damage recognition . . . . . . . . . . . . . . . . .4 1.2Bearing monitoring with technical devices . . . . . . . .4 1.2.1Wide-spread damage . . . . . . . . . . . . . . . . . . . . . . . . .4 1.2.2Damage in certain spots . . . . . . . . . . . . . . . . . . . . . . .6 1.3Urgency of bearing exchange – remaining life . . . . .7 2Securing damaged bearings . . . . . . . . . . . . . . . . . . .9 2.1Determination of operating data . . . . . . . . . . . . . . . .9 2.2Extraction and uation of lubricant samples . . . .9 2.3Inspection of bearing environment . . . . . . . . . . . . .10 2.4Assessment of bearing in mounted condition . . . . .10 2.5Dismounting damaged bearing . . . . . . . . . . . . . . . .10 2.6Seat check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 2.7Assessment of complete bearing . . . . . . . . . . . . . . .10 2.8Dispatch to FAG or assessment of individual parts of bearing . . . . . . . .10 3uation of running features and damage to dismounted bearings . . . . . . . . . . . . . . .11 3.1Measures to be taken . . . . . . . . . . . . . . . . . . . . . . . .14 3.1.1Marking separate parts . . . . . . . . . . . . . . . . . . . . . . .14 3.1.2Measurements taken with complete bearing . . . . . .14 3.1.3Dismantling bearing into separate parts . . . . . . . . .14 3.1.4Assessment of bearing parts . . . . . . . . . . . . . . . . . . .14 3.2The condition of the seats . . . . . . . . . . . . . . . . . . . .15 3.2.1Fretting corrosion . . . . . . . . . . . . . . . . . . . . . . . . . .15 3.2.2Seizing marks or sliding wear . . . . . . . . . . . . . . . . . .16 3.2.3Uneven support of bearing rings . . . . . . . . . . . . . . .17 3.2.4Lateral grazing tracks . . . . . . . . . . . . . . . . . . . . . . . .18 3.3Pattern of rolling contact . . . . . . . . . . . . . . . . . . . . .19 3.3.1Source and significance of tracks . . . . . . . . . . . . . . .19 3.3.1.1 Normal tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 3.3.1.2 Unusual tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.3.2Indentations in raceways and rolling element surfaces . . . . . . . . . . . . . . . . . . . . . .27 3.3.2.1 Fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 3.3.2.2 Corrosion damage . . . . . . . . . . . . . . . . . . . . . . . . . .34 3.3.2.3 False brinelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 3.3.2.4 Rolling element indentations . . . . . . . . . . . . . . . . .37 3.3.2.5 Craters and fluting due to passage of electric current . . . . . . . . . . . . . . . . . . . .38 3.3.2.6 Rolling element edge running . . . . . . . . . . . . . . . . .39 3.3.3Ring fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 3.3.3.1 Fatigue fractures as a result of raceway fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 3.3.3.2 Axial incipient cracks and through cracks of inner rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 3.3.3.3 Outer ring fractures in circumferential direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 3.3.4Deep scratches and smear marks on the contact surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 3.3.4.1 Wear damage with poor lubrication . . . . . . . . . . . .42 3.3.4.2 Scratches on rolling element outside diameters . . .44 3.3.4.3 Slippage tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 3.3.4.4 Score marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 3.3.5Damage due to overheating . . . . . . . . . . . . . . . . . . .47 3.4Assessment of lip contact . . . . . . . . . . . . . . . . . . . . .48 3.4.1Damage to lip and roller faces in roller bearings . . .48 3.4.1.1 Scoring due to foreign particles . . . . . . . . . . . . . . . .48 3.4.1.2 Seizure in lip contact . . . . . . . . . . . . . . . . . . . . . . . .49 3.4.1.3 Wear in the lip contact area . . . . . . . . . . . . . . . . . . .50 3.4.1.4 Lip fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 3.4.2Wear of cage guiding surfaces . . . . . . . . . . . . . . . . .52 3.4.3Damage to seal running areas . . . . . . . . . . . . . . . . .53 3.4.3.1 Worn sealing lip tracks . . . . . . . . . . . . . . . . . . . . . .53 3.4.3.2 Discolouration of sealing track . . . . . . . . . . . . . . . .53 3.5Cage damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 3.5.1Wear due to starved lubrication and contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 3.5.2Wear due to excess speed . . . . . . . . . . . . . . . . . . . . .54 3.5.3Wear due to roller skewing . . . . . . . . . . . . . . . . . . .55 3.5.4Wear in ball bearing cages due to tilting . . . . . . . . .55 3.5.5Fracture of cage connections . . . . . . . . . . . . . . . . . .56 3.5.6Cage fracture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 3.5.7Damage due to incorrect mounting . . . . . . . . . . . .57 3.6Sealing damage . . . . . . . . . . . . . . . . . . . . . . . . . . . .58 3.6.1Wear of sealing lips . . . . . . . . . . . . . . . . . . . . . . . . .58 3.6.2Damage due to incorrect mounting . . . . . . . . . . . .59 4Other means of inspection at FAG . . . . . . . . . . . . .60 4.1Geometric measuring of bearings and bearing parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 4.2Lubricant analyses and lubricant inspections . . . . .63 4.3Material inspection . . . . . . . . . . . . . . . . . . . . . . . . .65 4.4X-ray micro structure analysis . . . . . . . . . . . . . . . . .66 4.5Scanning electron microscope investigations . . . . .67 4.6Component tests . . . . . . . . . . . . . . . . . . . . . . . . . . .69 4.7Calculation of load conditions . . . . . . . . . . . . . . . .71 3FAG PagePage 标准分享网 w w w .b z f x w .c o m 免费下载 SymptomsSources of troubleExamples Uneven runningDamaged ringsMotor vehicles or rolling elementsmore and more wheel wobbling increased tilting clearance vibration of steering system Contamination Fans growing Excessive bearing clearancevibration Saw mills more knocks and blows in connecting rods ReducedWear due Lathe working accuracyto contaminantsgradual development or insufficient lubricationof chatter marks on workpiece Damaged ringsGrinders or rolling elementswavy ground surface Change in adjustmentCold rolling mill clearance or preloadPeriodic surface defects on rolled material such as stretcher strains, ghost lines etc. UnusualInsufficient operating clearance running noise whining or squealing noise Electric motors rumblingExcessive clearanceGears or irregularDamaged contact areasthe bearing noise noiseContaminationis hard to identify Unsuitable lubricantsince it is generally drowned by the noise of the gears gradual changeChange in operating clearance in running noisedue to temperature Damaged running track e.g. due to contamination or fatigue Unusual operating behaviour indicating damage Subjective damage recognition Bearing monitoring with technical devices Gradual deterioration of the opera- ting behaviour is normally the first sign of bearing damage. Spontaneous damage is rare, for example that caused by mount- ing errors or a lack of lubrication, which leads to immediate machine down- time. Depending on the operating con- ditions, a few minutes, or under some circumstances even a few months, may pass from the time damage begins to the moment the bearing actually fails. The case of application in question and the effects of bearing damage on the ma- chine operation are taken as a basis when selecting the type of bearing monitoring to be provided. 1.1 Subjective damage recognition In the vast majority of bearing appli- cations it is sufficient when machine operators watch out for uneven running or unusual noise in the bearing system, see table 1. 1.2 Bearing monitoring with technical devices Bearings which could be hazardous when damaged or which could lead to long production down-times require on the other hand accurate and constant monitoring. Two examples are jet engine turbines and paper-making machines. For monitoring to be reliable, its extent must be based on the type of damage which may be expected. 1.2.1 Wide-spread damage A sufficient supply of clean lubricant is the main precondition for trouble-free operation. Undesirable changes can be detected by FAG4 1 Unusual operating behaviour indicating damage 1 Recognition of damage by operating staff Temper- ature 10 20 30 40 50 C 1 2 3 4 5 12345 Life 012h 50 Life Temper- ature 10 012h 20 30 40 C 1 2 3 4 5 12345 Unusual operating behaviour indicating damage Bearing monitoring with technical devices 5FAG – Monitoring lubricant supply oil level window measuring oil pressure measuring oil flow – Measuring abraded matter in lubricant at intervals magnetic plug spectral analysis of lubricant samples inspection of oil samples in the lab continuously magnetic signal transmitter finding amount of particles flowing through with an online particle counter – Measuring temperature generally with thermocouples 2 March of temperature with intact main spindle bearings in a machine tool. Test condition n dm 750 000 min–1 mm. 3 March of temperature with disturbed floating bearings. Test condition n dm 750 000 min–1 mm. A very reliable and relatively easy way of recognising damage caused by inade- quate lubrication is by measuring the temperature. Normal temperature behaviour – reaching a steady state temperature in stationary operation, fig. 2. Disturbed behaviour – sudden rise in temperature caused by lack of lubricant or by the occurrence of excessive radial or axial preload on the bearings, fig. 3. – uneven march of temperature with maximum values tending to rise due to general deterioration of lubrica- tion condition , e.g. with attained grease service life, fig. 4. Measuring the temperature is not suitable, however, to register local damage at an early stage, e.g. fatigue. 24 40 h Time 60 80 Temper- ature C 0 4 March of temperature as a function of time with failing grease lubrica- tion. Test condition n dm 200 000 min–1 mm. 23 标准分享网 w w w .b z f x w .c o m 免费下载 Unusual operating behaviour indicating damage Bearing monitoring with technical devices FAG6 406080100120140160180200 Undamaged bearing Damaged bearing Vibration acceleration 0,086g 0,086g 0 Frequency [Hz] Side bands Side bands Harmonic fIR nIR 20 0 nIR 2fIR nIRnIR 3fIR nIRnIR 4fIR 5 Frequency spectrum of envelope signal between 0 and 200 Hz, below undamaged bearing; above damaged bearing nIRInner ring speed [min–1] fIRFrequency of inner ring signal cycling frequency [Hz] 6 Inner ring damage to a spherical roller bearing in a paper making machine found by means of the envelope detection procedure. 04812162024min Operation time 8040 100 120 140 160 60 80 100 300 Temperature C Shock value Lubrication stopped 7 March of temperature and shock value as a function of time stopping lubrication. Spindle bearing B7216E.TPA; P/C 0.1; n 9000 min–1; Lubricating oil ISO VG100. 1.2.2 Damage in certain spots Should bearing damage be restricted to specific locations such as indentations caused by rolling elements, standstill corrosion or fractures, it can be re- cognised at the earliest with vibration measurements. Shock waves which originate from the cycling of local inden- tations can be recorded by means of path, speed and acceleration pick-ups. These signals can be processed further at little or great expense depending on the operating conditions and the accuracy of the expected confidence factor. The most common are – measuring effective value – measuring shock value – signal analysis by envelope detection. Experience has shown that the latter procedure is particularly reliable and practical in use. The damaged bearing components can even be pinpointed with a special type of signal processing, figs. 5 and 6. Please refer to our TI No. WL 80-36 Rolling Bearing Diagnosis with the FAG Bearing Analyser“ for more ination. Unusual operating behaviour indicating damage Bearing monitoring with technical devices Urgency of bearing exchange 7FAG The vibration measuring procedures are very suitable for detecting fatigue damage. It is easiest with bearings with point contact ball bearings and with more sophisticated uation proce- dures such as envelope detection, for ex- ample, damage to roller bearings is found just as reliably. They are less suit- able, however, for observing the lubrica- tion condition. A fault in the lubricant supply can be reliably spotted by tem- perature measuring, as described above. This is particularly well illustrated in figure 7. The shock value is far less sen- sitive than the temperature sensor. Hence, in the case of expensive technical plants, temperature and vibration measurements complement one another ideally. 8 Development of fatigue damage on the inner ring raceway of an angular contact ball bearing. The periodic intervals between inspections from damage begin on, are given in percentage o