CN110967186B - Method for judging overheating color change trace of main bearing of aero-engine - Google Patents
Method for judging overheating color change trace of main bearing of aero-engine Download PDFInfo
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- CN110967186B CN110967186B CN201911140003.4A CN201911140003A CN110967186B CN 110967186 B CN110967186 B CN 110967186B CN 201911140003 A CN201911140003 A CN 201911140003A CN 110967186 B CN110967186 B CN 110967186B
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
- G01M13/04—Bearings
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- G—PHYSICS
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- G—PHYSICS
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/29—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using visual detection
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Abstract
A method for judging an overheating color change trace of a main bearing of an aero-engine, in particular to a method for judging an overheating color change trace of a main bearing after running-in and trial run of the aero-engine. The method specifically comprises the following steps: 1) removing impurities and oil on the surface of the main bearing; 2) judging whether the main bearing is scrapped or can be normally used according to the color wiping condition of the surface layer; 3) putting the main bearing which is determined to be oxidized and coked by the lubricating oil into a saturated sodium carbonate aqueous solution for cleaning and neutralizing; 4) and detecting the size of the main bearing. The invention has good field engineering application and stable state, and solves the problem of main bearing scrapping caused by inaccurate judgment of the overheating color change trace.
Description
Technical Field
The invention belongs to the technical field of design of an aero-engine mechanical system, and particularly relates to a method for judging an overheating color change trace of a main bearing after an aero-engine running-in test, which avoids the problems that the main bearing is scrapped due to inaccurate judgment of the overheating color change trace, and further a new main bearing is required to be reassembled for additional test running, so that the cost is increased and the production period is delayed.
Background
An aircraft engine generally comprises a compressor system, a turbine system, a mechanical system, an operating system, a combustion chamber system, a nozzle system and the like. One of the mechanical systems, which may also be referred to as a power transmission system or a transmission and lubrication system, mainly includes an engine main bearing, a lubricating oil system and assembly, a main bearing cavity, a main bearing sealing pressurization system and sealing device, a central transmission and external gearbox, and the like. The main bearing of the engine has the functions of centrally and axially positioning the rotor and the casing or supporting the rotor on other rotors; all axial and radial forces of the rotor are transmitted to the casing member. The basic function of the lubricating system is to provide lubricating oil for lubricating and cooling parts such as engine main bearings, transmission mating surfaces, contact seal runways and the like, so as to reduce friction and abrasion of the motion mating surfaces, prevent corrosion and surface hardening, and simultaneously transfer heat away to take away hard inclusions formed between the mating surfaces.
The test run procedure of the aircraft engine comprises a running-in test run (a factory test run or an additional test run) and an inspection test run. The main bearing is used as a key part of the aero-engine, decomposition and inspection must be carried out after running-in and trial run, the test and trial run is continued if the fault detection requirement is met, otherwise, the main bearing is scrapped, and the main bearing must be replaced by a new bearing to carry out additional trial run examination again, so that the production cost is increased and the production period is delayed. In the statistics of the scrapping types of the main bearings, the scrapping rate is about 50% due to inaccurate judgment of the overheated discoloration marks and the oxidation coking of the lubricating oil.
The overheating discoloration mark is a light brown deposit or a blue-gray black (or purple) surface which appears on the surface of the main bearing when the temperature of the main bearing is increased by more than 200 ℃ for one time or more in the working process, the original metallic luster is lost, and if the temperature exceeds the tempering temperature of 350 ℃, the transformation of the metallographic structure of the material also appears. The main bearing discoloration is mainly caused by the following two reasons:
oxidation coking of lubricating oil
The bearing surface is exposed in a high-temperature environment, and the lubricating oil film attached to the bearing surface is heated and decomposed due to high temperature, scorched and dried, so that a layer of brown film is deposited on the bearing surface, and when the deposit is thicker, the color is changed into brown or darker. The deposit is the oxide of lubricating oil, does not affect the use of the bearing and does not belong to overheat discoloration.
(II) material discoloration by heat
When the working temperature of the bearing is increased or the lubrication is poor due to some reason, the bearing works in an abnormal state, the temperature is rapidly increased, the local temperature at the moment is possibly over the tempering temperature of the bearing part, so that a serious burn phenomenon occurs, the surface of the bearing is possibly blue-gray-black or even purple, the color change of the condition is called as overheating color change, and the bearing is rejected.
The conventional method for detecting the overheating color change trace comprises the steps of detecting the hardness of the main bearing by using a bearing hardness tester, wherein if the hardness is 60-64 HRC, the surface of the main bearing is oxidized and changed in color so as to be normally installed and used, otherwise, the main bearing is overheated and changed in color, and the main bearing is scrapped.
Because the main bearing is a precise part, the hardness inspection can only be performed on a non-working surface (such as a ferrule end face), and for parts such as a rolling body, the whole surface is a working surface, so that the hardness inspection cannot be performed, and thus a method for judging the overheating color change trace of the main bearing of the aircraft engine is urgently needed to be researched.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for judging the overheating discoloration trace of the main bearing of the aircraft engine, and related reports are not found in the method. The method specifically comprises the steps of adding an acidic cleaning solution with a certain proportion into an existing mature ultrasonic cleaning machine, judging whether the main bearing changes color to the end or whether the main bearing is oxidized and coked by lubricating oil or overheated and discolored by materials according to different time lengths, and further determining whether the main bearing is normally used or not, so that the use safety of an engine is guaranteed.
The invention relates to a method for judging an overheat discoloration mark of a main bearing of an aero-engine, which comprises the following specific steps:
step 1, pretreatment:
carrying out surface impurity removal and oil removal treatment on the main bearing to ensure that no blockage exists;
step 2, judging the color change of the overheating trace:
(1) distilled water, oxalic acid and nitric acid are weighed according to the mass percentage, and the acid solution component comprises oxalic acid C2H2O4: 5-10% of nitric acid HNO3: 5-10%, distilled water: the balance; sequentially adding the materials into a groove of an ultrasonic cleaning machine, heating and stirring uniformly, then putting the materials into a main bearing for ultrasonic treatment, turning the main bearing at intervals of 10min, and observing the surface state of the main bearing;
(2) taking out the main bearing and wiping, observing the color of the surface layer, judging the main bearing to be an overheated color changing mark if the color cannot be wiped off, and scrapping the main bearing; the color can be wiped off, so that the lubricating oil is oxidized and coked, and the main bearing is normally used;
step 3, alkali washing neutralization:
putting the main bearing determined to be oxidized and coked by the lubricating oil into a room-temperature saturated sodium carbonate aqueous solution for cleaning and neutralizing, wherein the cleaning time is 10-60 min;
and 4, detection:
wiping the surface of the main bearing, smearing oil, standing at constant temperature for 4h, removing oil by using an organic solvent, measuring the size, and packaging and storing qualified products.
The method for judging the overheat discoloration mark of the main bearing of the aircraft engine comprises the following steps:
in the steps 1 and 4, the impurity removal solvent is gasoline, acetone or hydrocarbon cleaning agent.
In the step 2(1), the heating temperature of the acid solution is 50-70 ℃, the ultrasonic time is 30-60 min, and the ultrasonic frequency is 20-30 KHz.
The technical points of the invention are as follows:
(1) ultrasonic cleaning machine
The impact action generated in the liquid by the sound wave vibration and the high-speed micro-jet generated on the solid and liquid interface by the ultrasonic cavitation can remove or weaken attachments on the surface of the main bearing at the boundary, increase the stirring action, accelerate the dissolution of the attachments and strengthen the chemical dissolution action of acid liquid on the attachments and the like.
If the surface of the main bearing has oxidation coking of the lubricating oil, the ultrasonic cleaning machine can dissolve the oxidation coking of the lubricating oil by virtue of an acidic solution, the color of the main bearing is presented, and the main bearing can be normally used; if the surface of the main bearing has the overheat discoloration mark, the mark on the surface of the main bearing cannot be dissolved by the ultrasonic cleaning machine with the help of an acid solution, the organism structure of the material belonging to the main bearing changes, and the main bearing is scrapped.
(2) Acidic cleaning solution and cleaning duration
And finally determining the optimal acid solution ratio (in terms of mass ratio) for judging the main bearing overheating color change trace through multiple times of acid solution ratio and accumulated verification of cleaning duration.
The acid solution ratio is as follows: oxalic acid C2H2O4: 5-10% of nitric acid HNO3: 5-10%, distilled water: 80-90%, the cleaning time is long: 30-60 min; ultrasonic frequency: 20 to 30KHz; temperature: 50-70 ℃.
(3) Process parameters
The ultrasonic frequency is 20-30 KHz; the temperature of the ultrasonic cleaning machine is 50-70 ℃, and the cleaning time is 30-60 min.
(4) Judging method
When the device is used, distilled water, oxalic acid and nitric acid with certain volumes are poured into a tank of an ultrasonic cleaning machine in sequence, and acid liquor is stirred uniformly (the height of the acid liquor can be ensured to submerge a main bearing or a bearing part). The frequency of the ultrasonic cleaning machine is adjusted to 20-30 KHz, and the temperature is set to 50-70 ℃. And (3) after the temperature is reached, putting the main bearing needing to judge the overheat discoloration mark into acid liquor, taking out the main bearing after 30-60 min, and wiping the surface of the main bearing by gauze or cotton balls. If the color cannot be wiped off, the main bearing is an overheated color change mark and is scrapped; if the main bearing can be wiped off, the main bearing is oxidized and coked by lubricating oil, and the main bearing is normally used.
(5) Process flow
The process flow is as follows:
organic solvent lubricating oil removal (such as gasoline) → judgment of overheat discoloration mark → wiping of the surface of the main bearing with gauze or cotton ball → Na2CO3Saturated soda solution cleaning neutralization → absorbent paper absorbs the solution on the surface of the main bearing dry → the surface of the main bearing is coated with 8A aviation lubricating oil → constant temperature for 4 hours → organic solvent removes lubricating oil (such as gasoline) → size measurement → qualified product loading machine or package preservation. If the main bearing is judged to be the material overheating color change problem in the overheating color change trace judging step, the main bearing is directly scrapped; if the oil is oxidized and coked, the next operation is continued.
The sizes of parts of the main bearing are different, and the condition that the inner ring or the outer ring is provided with the oil hole exists, the main bearing needs to be cleaned by an organic solvent before judging the overheat discoloration trace, so that no obvious attachment and residual lubricating oil exist on the surface, and if the oil hole is provided with a plug, the plug needs to be taken out and the oil hole is ensured to be permeable.
And (3) putting the deoiled main bearing into an acid liquor of an ultrasonic cleaning machine, controlling the ultrasonic frequency to be 20-30 KHz, setting the temperature to be 50-70 ℃, turning the main bearing every 10min, and observing the surface state of the main bearing at any time. If the oil is oxidized and cokedThe surface of the main bearing presents metallic luster, and the main bearing is taken out and placed on Na2CO3After washing and neutralization in saturated soda solution, the next work is carried out.
The invention has the advantages and effects that:
(1) the invention has good field engineering application and stable state, and solves the problems of cost increase, production cycle delay and the like caused by the fact that the main bearing is scrapped due to inaccurate judgment of the overheating color change trace and further a new main bearing needs to be reassembled for additional test run.
(2) Has direct economic effect. 5 individual main bearings of aeroengine, about 5 ten thousand yuan of each cover, judge because of overheated color changing trace and abandon inadequately according to 1 set of main bearing, and single aeroengine main bearing can practice thrift 5 ten thousand yuan of cost.
(3) Has social benefits. The judging method is simple to operate and low in production cost, is popularized and applied to judging the overheating color change traces of various bearings, prevents the bearings with overheated materials from being installed on the engine, and ensures the use safety of the engine.
(4) The method is suitable for judging the main bearing made of various materials, and comprises the following steps: m50 steel, W9Cr4V2Mo steel and Cr15 steel.
Drawings
FIG. 1 is a flowchart of the operation process of the method for judging the overheating discoloration mark of the main bearing of the aircraft engine in embodiments 1 to 3 of the present invention.
Detailed Description
The specific operational process flow of examples 1-3 is shown in FIG. 1.
Example 1
In this embodiment 1, the main bearing material is M50 steel, and the acid solution comprises, by mass, oxalic acid: 10%, nitric acid: 10%, distilled water: and (4) the balance.
The method for judging the overheat discoloration mark of the main bearing of the aircraft engine comprises the following specific implementation steps of:
step 1, pretreatment:
cleaning the surface of the main bearing by using gasoline, removing oil and impurities to ensure no blockage;
step 2, judging the color change of the overheating trace:
(1) weighing distilled water, oxalic acid and nitric acid according to mass percentage, sequentially adding the distilled water, the oxalic acid and the nitric acid into a tank of an ultrasonic cleaning machine, stirring and heating acid liquor to 50 ℃, wherein the ultrasonic frequency is 30 KHz; putting the main bearing needing to judge the overheating color change trace into acid liquor, and carrying out ultrasonic treatment for 60 min; turning the main bearing every 10min, and observing the surface state of the main bearing;
(2) the main bearing is taken out and the surface of the main bearing is wiped by gauze, the color can be wiped off, the main bearing is oxidized and coked by lubricating oil, and the main bearing can be normally used;
step 3, alkali washing neutralization:
putting the main bearing into a saturated sodium carbonate aqueous solution at room temperature, and cleaning for 10 min;
and 4, detection:
wiping the surface of the main bearing, smearing 8A aviation lubricating oil, standing at constant temperature for 4h, removing oil with hydrocarbon cleaning agent, measuring size, packaging and storing.
Example 2
In this embodiment 2, the main bearing material is W9Cr4V2Mo steel, and the acid solution comprises, by mass, oxalic acid: 10%, nitric acid: 5%, distilled water: and (4) the balance.
The method for judging the overheat discoloration mark of the main bearing of the aircraft engine comprises the following specific implementation steps of:
step 1, pretreatment:
cleaning the surface of the main bearing by acetone, and removing impurities and oil to ensure no blockage;
step 2, judging the color change of the overheating trace:
(1) weighing distilled water, oxalic acid and nitric acid according to mass percentage, sequentially adding the distilled water, the oxalic acid and the nitric acid into a tank of an ultrasonic cleaning machine, stirring and heating acid liquor to 70 ℃, wherein the ultrasonic frequency is 25 KHz; putting the main bearing needing to judge the overheating color change trace into acid liquor, and carrying out ultrasonic treatment for 40 min; turning the main bearing every 10min, and observing the surface state of the main bearing;
(2) the main bearing is taken out and the surface of the main bearing is wiped by a cotton ball, the color can be wiped off, the main bearing is oxidized and coked by lubricating oil, and the main bearing can be normally used;
step 3, alkali washing neutralization:
putting the main bearing into a saturated sodium carbonate aqueous solution at room temperature, and cleaning for 60 min;
and 4, detection:
wiping the surface of the main bearing, smearing 8A aviation lubricating oil, standing at constant temperature for 4h, removing oil with a hydrocarbon cleaning agent, measuring the size, and loading the qualified product for reuse.
Example 3
In this embodiment 3, the main bearing is made of Cr15 steel, and the acid solution comprises, by mass, oxalic acid: 5%, nitric acid: 10%, distilled water: and (4) the balance.
The method for judging the overheat discoloration mark of the main bearing of the aircraft engine comprises the following specific implementation steps of:
step 1, pretreatment:
cleaning the main bearing by using gasoline to remove surface attachments and residual lubricating oil and ensure that no blockage exists;
step 2, judging the color change of the overheating trace:
(1) weighing distilled water, oxalic acid and nitric acid according to mass percentage, sequentially adding the weighed materials into a tank of an ultrasonic cleaning machine, stirring and heating acid liquor to 50-70 ℃, wherein the ultrasonic frequency is 20 KHz; putting the main bearing needing to judge the overheating color change trace into acid liquor, and carrying out ultrasonic treatment for 30 min; turning the main bearing every 10min, and observing the surface state of the main bearing;
(2) the main bearing is taken out and the surface of the main bearing is wiped by gauze, the color can be wiped off, the main bearing is oxidized and coked by lubricating oil, and the main bearing can be normally used;
step 3, alkali washing neutralization:
putting the main bearing confirmed to be oxidized and coked by the lubricating oil into a room-temperature saturated sodium carbonate aqueous solution for cleaning for 30 min;
and 4, detection:
wiping the surface of the main bearing, smearing 8A aviation lubricating oil, standing at constant temperature for 4h, removing oil with acetone, measuring size, packaging and storing.
Claims (3)
1. A method for judging an overheat discoloration mark of an aircraft engine main bearing is characterized by comprising the following specific steps:
step 1, pretreatment:
carrying out surface impurity removal and oil removal treatment on the main bearing to ensure that no blockage exists;
step 2, judging the color change of the overheating trace:
(1) weighing distilled water, oxalic acid and nitric acid according to mass percent, wherein the acid liquid comprises the following components in percentage by mass: oxalic acid C2H2O4: 5-10% of nitric acid HNO3: 5-10%, distilled water: the balance; sequentially adding the materials into a groove of an ultrasonic cleaning machine, heating and stirring uniformly, then putting the materials into a main bearing for ultrasonic treatment, turning the main bearing at intervals of 10min, and observing the surface state of the main bearing;
(2) taking out the main bearing and wiping, and observing the color of the surface layer; if the color cannot be erased, judging the color is an overheated color changing trace, and scrapping the main bearing; the color can be wiped off, so that the lubricating oil is oxidized and coked, and the main bearing is normally used;
step 3, alkali washing neutralization:
putting the main bearing determined to be oxidized and coked by the lubricating oil into a room-temperature saturated sodium carbonate aqueous solution for cleaning and neutralizing, wherein the cleaning time is 10-60 min;
and 4, detection:
wiping the surface of the main bearing, smearing oil, standing at constant temperature for 4h, removing oil, measuring size, and packaging.
2. The method for judging the overheat discoloration mark of the main bearing of an aircraft engine according to claim 1, wherein in steps 1 and 4, an organic solvent is used for removing impurities and oil, and the organic solvent is gasoline, acetone or a hydrocarbon cleaning agent.
3. The method for judging the overheat discoloration mark of the main bearing of an aircraft engine according to claim 1, wherein in the step 2(1), the heating temperature of the acid solution is 50-70 ℃, the ultrasonic time is 30-60 min, and the ultrasonic frequency is 20-30 KHz.
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