CN111766064A - Ship-borne main shaft bearing impact test method - Google Patents
Ship-borne main shaft bearing impact test method Download PDFInfo
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Abstract
The invention belongs to the technical field of aircraft engine main bearing impact tests, and discloses a ship-borne main shaft bearing impact test method which comprises the steps of placing a main shaft bearing to be tested on a test platform, controlling the main shaft bearing to rotate according to a set rotating speed, applying a preset load spectrum to the main shaft bearing, operating for a certain time, measuring to obtain state parameters of the main shaft bearing, changing the rotating speed of the main shaft bearing, repeating the process until all preset rotating speeds and cycle times are completed, matching a certain load with a corresponding rotating speed and loading for a certain time through the load spectrum, wherein the load comprises an axial load and a radial load. The invention provides a set of complete main bearing impact test method, reduces the technical risk of model development, provides a theoretical basis for the technical research on the large overload damage life of the carrier-based main shaft bearing, and lays a technical foundation for the early train installation of carrier-based power equipment.
Description
Technical Field
The invention belongs to the technical field of an aircraft engine main bearing impact test, relates to a technical method for a ship-borne main shaft bearing large overload damage mechanism simulation and service life verification test, and particularly relates to a ship-borne main shaft bearing impact test method.
Background
The main bearing of the aero-engine is used for supporting the main shaft and bearing the aerodynamic load transmitted by the engine wheel disc. The working performance, the service life, various performance indexes and the reliability of the main bearing aeroengine are greatly influenced. In some cases, failure of the main bearings of an aircraft engine can have the consequence of causing aircraft crash and death.
The main bearings of the ship-borne advanced trainer engine are distributed at five positions on the main shaft. For a carrier-based aircraft engine, in the service process, the carrier-based aircraft engine inevitably experiences the working states of severe working conditions such as catapult takeoff and carrier arresting, and the like, and the main bearing of the engine bears axial and radial overload in the process, which has important influence on the working performance of the main bearing. With the continuous improvement of the performance requirements of the airplane and the harsher performance of the working environment of the airplane, the operation working condition of the aero-engine is more and more severe, and therefore the performance requirements on the main bearing of the aero-engine are higher.
Modern aircraft engines are moving towards large thrust-to-weight ratios, low fuel consumption, high reliability, high durability, and long life. However, with the continuous improvement of the performance of the aircraft engine and the continuous increase of the thrust-weight ratio and the rotating speed of the rotor, the working conditions of the transmission system are more and more strict. The main shaft bearing is used as a key element of the aircraft engine and is a weak link of the aircraft engine, and the reliability and the service life of the aircraft engine are directly influenced by the performance of the main shaft bearing. The progress and development of aeronautical science and technology have made higher requirements on the structural design, material selection, lubricating method, test analysis and the like of the main shaft bearing. Meanwhile, the following special requirements are also put forward on the main shaft bearing:
a) the failure of the bearing can cause the vibration of the rotor of the engine to be increased and even serious accidents to happen, so that the reliability requirement on the bearing is high;
b) the bearing can work normally under the conditions of high temperature and low temperature, and has longer service life;
c) the bearing can bear the radial load of the rotor or bear the radial load and the axial load simultaneously, and has larger bearing capacity;
d) the structure is light in weight and has enough rigidity, the force transmission between the rotating shaft and the bearing seat can be ensured, the collision and the vibration between the rotating shaft and the bearing seat can be relieved, and the rotor of the engine can stably run.
The main shaft bearing is an indispensable component in a force bearing system of the aircraft engine, and the harsh operating condition of the modern aircraft engine causes the main shaft bearing to face more serious challenges:
a) high DN value
The DN value is the product of the inner diameter of the main shaft bearing and the rotating speed. The thrust-weight ratio of modern aircraft engines is continuously increased, and long service life and high reliability are required, and the main technical approach for improving the thrust-weight ratio is to improve the working rotating speed of a main shaft bearing of the engine, so that the main shaft bearing is promoted to develop towards high speed. The increase of the rotating speed of the engine and the diameter of the main shaft bearing inevitably causes the increase of the speed index DN value of the main shaft bearing.
b) High temperature
For aircraft engines, the temperature of the working environment of the main shaft bearing is also high due to the extremely high temperature at the turbine inlet. At present, due to the limitation of the performance of lubricating oil, the working temperature of a main shaft bearing of an aeroengine has certain limitation requirements. Due to the higher temperature, on one hand, the hardness of the main shaft bearing material is reduced, which leads to the reduction of the bearing capacity and the reduction of the fatigue life; on the other hand, the higher temperature reduces the viscosity of the lubricating oil, causes the film thickness to be reduced so as to be in a severe mixed lubrication state, the surface shear stress is obviously increased, the maximum shear stress is moved to the surface, the surface friction heat generated by the surface friction heat is more likely to cause the thickness of the oil film to be reduced and even to be broken, and the local friction and the heat generation are increased after the lubricating oil film is broken.
c) Large overload
In addition to the requirement of high speed and high temperature operation, the rapid development of modern aircraft engines also requires that the main shaft bearing simultaneously operates under a large overload condition, and the thrust load borne by the main shaft bearing in the future aircraft engine is higher and higher. The coexistence of high speed, high temperature and large overload working conditions causes the aeroengine main shaft bearing to be in a more severe working environment, thereby increasing the possibility of failure and damage of the main shaft bearing and reducing the service life of the main shaft bearing. Therefore, the "high speed" and "heavy load" of the spindle bearing cannot be defined by only a single index.
If the spindle bearing fails, it will cause a reduction in system accuracy, increased vibration and poor stability, and if it fails, it will cause the spindle bearing to seize and possibly damage the machine. Therefore, the tribological performance and the temperature rise characteristic of the main shaft bearing, especially the main shaft bearing of an aircraft engine, are required to be studied deeply, and the large overload resistance of the main shaft bearing is required to be tested.
However, in the currently disclosed documents, there is no impact test method for the main shaft bearing of the engine of the carrier-based aircraft, and the impact test methods for other bearings cannot meet the test requirements for the main shaft bearing of the carrier-based aircraft.
Currently, the corresponding standards are: national military standard of the people's republic of China "life program and requirements for aero-engine bearing test" (GJB7268-2011) and national standard of the people's republic of China "life and reliability test and assessment of rolling bearing" (GB/T24607-2009).
Disclosure of Invention
In order to solve the problems, the application provides a ship-based main shaft bearing impact test method, which provides a theoretical basis for the technical research on the large overload damage life of a ship-based main shaft bearing and lays a technical foundation for the early train installation of ship-based power equipment.
The technical scheme of the invention is as follows: a ship-borne main shaft bearing impact test method comprises the following steps:
firstly, a main shaft bearing to be tested is placed on a test platform;
step two, controlling the main shaft bearing to rotate according to a set rotating speed;
step three, applying a preset load spectrum to the main shaft bearing, operating for a certain time and measuring to obtain the state parameters of the main shaft bearing;
step four, changing the rotating speed of the main shaft bearing, and repeating the processes of the step two and the step three until all preset rotating speeds and cycle times are finished;
step five, disassembling the spindle bearing after the test is finished, and evaluating the test result;
the load spectrum is that a certain load is matched with a corresponding rotating speed and is loaded for a certain time, and the load comprises an axial load and a radial load; the corresponding rotating speed is that the rotating speed of the main shaft bearing under the slow, cruising, maximum cruising, rated, middle and maximum states of the airplane, the running time and the cycle number of each rotating speed are set according to different states of the airplane; the airplane has certain rotating speed in different states, the rotating speed has specific load and lasts for certain time, and the three are matched to form a preset load spectrum.
Further, at the maximum state of the airplane, the rotation speed, the running time and the cycle number of the main shaft bearing are added with an axial overload coefficient of 5g and a radial overload coefficient of 8g into the load calculation.
Further, the applied axial load is calculated at each operating load condition based on the aerodynamic parameters of the compression system and turbine components, and the boundary values for the motoring load are-5 g and +5 g.
Further, the axial loads include rotor blade static airflow pressure axial forces FjAxial force F of rotor blade airflow static pressurejThe expression of (a) is:
in the formula, Dk1The diameter of the blade tip of the inlet section of the blade; dk2The diameter of the blade tip of the outlet section of the blade; dH1Is the inlet section of the bladeThe diameter of the root of the facial leaf; dH2The diameter of the blade root is the outlet section of the blade; p1The average airflow static pressure of the inlet section of the blade is taken as the average airflow static pressure; p2The average airflow static pressure of the blade outlet section is obtained; pk1Static pressure of airflow at the blade tip of the inlet section of the blade; pk2And the static pressure of the airflow at the blade tip of the outlet section of the blade.
Further, the axial load includes an axial force F generated by the axial velocity of the airflow on the bladevAxial force F generated by the axial velocity of the air flow on the bladevThe expression of (a) is:
Fv＝∑Qa(Ca2-Ca1) (2)
in the formula, QaIs the air flow rate; ca1The average axial velocity of the airflow at the inlet section of the blade; ca2The average axial velocity of the airflow at the outlet section of the blade.
Further, the axial load includes an axial force F generated by the static airflow pressure of the annular cavity or the pressure of the lubricating oil cavityQAxial force F generated by the static airflow pressure of the ring cavity or the pressure of the lubricating oil cavityQThe expression of (a) is:
in the formula, PQStatic airflow pressure or lubricating oil cavity pressure of the annular cavity; dKThe outer diameter of the annular cavity; dHThe inner diameter of the annular cavity.
Further, the applied radial load is the load generated by the motor overload and the residual unbalance amount of the rotor, and is calculated according to each working state point and the corresponding rotor rotating speed, and the maximum overload coefficient is 8 g.
Further, the radial load includes an imbalance force FTAnd gravity FGUnbalanced force FTAnd gravity FGThe expression of (a) is:
FT＝miω2(7)
FG＝mfg (8)
in the formula, miThe amount of the residual unbalance of the rotor; m isjIs a rotor weightAn amount; ω is the angular velocity.
The invention has the advantages that: the method provided by the invention provides a set of complete main bearing impact test method, reduces the technical risk of model development, provides a theoretical basis for the technical research on the large overload damage life of the carrier-based main shaft bearing, and lays a technical foundation for the early train installation of carrier-based power equipment.
Drawings
FIG. 1 is a schematic diagram of an experimental simulation method of the present invention;
FIG. 2 is a schematic diagram of measured intercept overload of a certain carrier-based aircraft over time according to an embodiment of the invention;
the device comprises a bearing, a main shaft, a radial loading device, a main shaft and a test bearing, wherein the axial loading device is 1, the radial loading device is 2, and the main shaft is 3 and the bearing is 4.
Detailed Description
This section is an example of the present invention and is provided to explain and illustrate the technical solutions of the present invention.
The main shaft bearing in the aircraft engine often operates under the harsh working conditions of high speed, high temperature and heavy load, and particularly the rolling body and the roller path of the main shaft bearing of the carrier-based aircraft engine are often in a mixed lubrication state. The rolling bodies have high spin speed and sliding speed, and the outer raceway bears high load due to centrifugal force of the rolling bodies, and the factors have great influence on the temperature rise, power loss and fatigue life of the main shaft bearing. On the basis of considering the actual working condition of the aero-engine, the working load state of the main shaft bearing is analyzed, the influence of high speed, high temperature and large overload on the performance of the main shaft bearing is inspected, and a main shaft bearing large overload resistance test scheme is established and examined.
Firstly, making load spectrum of main shaft bearing anti-large overload test
In the process of catapult takeoff and arresting landing of the carrier-based aircraft, the acceleration load and the arresting braking load of the catapult device can generate a larger inertial load effect on the aircraft engine structure, so that a larger load effect is brought to the main shaft bearing. At present, most of load spectrums of main shaft bearing tests are subjected to mechanical analysis according to the working conditions of land-based aeroengines, relevant detailed actual working condition analysis is not performed, certain errors exist in the formulation of the load spectrums, and the calculation precision is lacked. Therefore, before a load spectrum of a main shaft bearing large overload resistance test is prepared, a test working condition simulation method needs to be analyzed so as to check the method rationality. In actual conditions, because the influence of the rotor speed and the working load is large, how to make a load spectrum of a main shaft bearing large overload resistance test is the content of the key research of the invention.
Second, the actual working condition of the main shaft bearing
When a ship-borne advanced trainer carries out catapult takeoff, fly-back and hook arresting training, overload generated in the axial direction directly acts on an engine, the load directions generated in the three training states are opposite, and if the structural design of a main bearing part is unreasonable or the strength margin is insufficient, cracks or instability and the like of a main bearing structural part can be caused, so that the use reliability of the engine is influenced. The main shaft bearing belongs to one of main bearing parts of an engine, and aiming at the main shaft bearing, when the main shaft bearing is in a blocking or catapult-assisted take-off state, a large overload effect exists, the strength and the service life of the main shaft bearing are influenced, and the temperature of lubricating oil can be improved by repeated large overload action. In addition, the axial pneumatic load of the high-pressure rotor and the low-pressure rotor can change the bearing direction of the main shaft bearing. And the axial force is too small, so that the slipping phenomenon can be caused, the service life of the main shaft bearing can be shortened, even the matching relation of the rotor is damaged, the main shaft bearing is failed, and the flight training safety is endangered. Therefore, the relationship between the airplane overload coefficient and the pre-tightening load and the pneumatic load of the main shaft bearing needs to be carefully analyzed, and the accuracy of the setting of the load spectrum of the main shaft bearing is ensured.
Method for simulating actual working condition of main shaft bearing
The test simulation mode is as shown in fig. 1, in order to simulate the actual working condition, the main shaft bearing of the engine can be installed on the main shaft and pre-tightened for positioning, and the test main shaft is used for simulating the rotation of the actual main shaft of the engine so as to drive the main shaft bearing of the engine to rotate together. The loading device is connected with the fixed ring, the oil cylinder is used for loading acting force, and the magnitude of the applied load is remotely controlled by the control system, so that the stepless speed regulation function of the load can be realized, the effect of simulating the actual working condition is achieved, and the flexibility of the test is improved.
Fourth, method for making load spectrum of anti-large overload test
The load spectrum is load data for describing the loading condition of the main shaft bearing of the aeroengine in flight use and is an important parameter for calculation and test of the main shaft bearing, so that the method carries out detailed theoretical analysis on the formulated method to ensure the rationality of the method.
The load of the load spectrum comprises an axial load and a radial load, the pneumatic axial force acting on the rotor consists of a runner axial force and axial forces of all chambers, wherein the runner axial force comprises airflow static pressure axial force and axial force generated by airflow axial speed, the chamber axial force consists of axial force generated by airflow static pressure of an air system or static pressure of all chambers of an oil cavity, and the direction of the axial force is usually defined to be forward along the heading direction as positive. Due to the action of the gravity and the unbalanced force of the rotor, the rotor system is also subjected to radial load, and the dynamic performance of the rotor system is greatly influenced.
1. Axial load
In order to meet the design criterion of the strength of the main shaft bearing and improve the calculation efficiency, the axial force of the rotor is calculated by the pneumatic parameters of a compression system and a turbine component under each working load state, the boundary value is selected for the maneuvering load, the ejection is-5 g, and the landing blocking is +5 g.
The rotor blade airflow static pressure axial force comprises airflow static pressure axial forces flowing through inlet and outlet sections of each stage of rotor of the engine and axial forces generated by static pressure of a blade tip annular cavity, and the expression is as follows:
in the formula, Dk1The diameter of the blade tip of the inlet section of the blade; dk2The diameter of the blade tip of the outlet section of the blade; dH1The diameter of the blade root is the inlet section of the blade; dH2The diameter of the blade root is the outlet section of the blade; p1The average airflow static pressure of the inlet section of the blade is taken as the average airflow static pressure; p2The average airflow static pressure of the blade outlet section is obtained; pk1Static pressure of airflow at the blade tip of the inlet section of the blade; pk2For static flow at blade tip of outlet section of bladeAnd (6) pressing.
According to the momentum theorem, the fluid is set as a control body, the impulse of the control body is equal to the momentum change, and therefore, the axial force generated by the axial speed of the airflow on the blade can be defined as follows:
Fv＝∑Qa(Ca2-Ca1) (2)
in the formula, QaIs the air flow rate; ca1The average axial velocity of the airflow at the inlet section of the blade; ca2The average axial velocity of the airflow at the outlet section of the blade.
That is, the flow channel axial force is:
FG＝Fj+Fv(3)
the axial force generated by the ring cavity airflow static pressure or the oil cavity pressure can be expressed as:
in the formula, PQFor the pressure D of the annular cavity airflow static pressure or the lubricating oil cavityKIs the outer diameter D of the annular cavityHThe inner diameter of the annular cavity.
In addition, the influence of the pneumatic axial force error is considered, the axial load is actually measured, and the calculation is corrected, so that the calculation accuracy is guaranteed.
2. Radial load
The radial load borne by the main shaft bearing is mainly the load generated by the maneuvering overload and the residual unbalance of the rotor, the stress condition of the rotor system under the actual working condition is considered, the radial overload coefficient of the engine is selected to be the maximum value, the overload coefficient is 8g, and the rotating speed of the rotor is selected according to each working state point.
Rotor moment and external force balance equation:
∑M＝F1L1+F2L2+····+FMLM(5)
∑F＝F1+F2+····+FM(6)
wherein, the acting force is; is the distance of the force to the point of action.
The expressions for the unbalanced force and the gravitational force are:
Fτ＝miω2(7)
FG＝mfg (8)
in the formula, miThe amount of the residual unbalance of the rotor; m isjIs the rotor weight; ω is the angular velocity.
3. Speed of rotation determination
When a load spectrum of a main shaft bearing in a large overload resistance test is designed, axial load and radial load are fully considered, and the rotating speed, the running time and the cycle number of the main shaft bearing in slow running, cruising, maximum cruising, rated, middle and maximum states are defined according to different states of an airplane. At the maximum, the axial overload factor of 5g and the radial overload factor of 8g are taken into account in the load calculation.
In summary, the establishment of the load spectrum of the main shaft bearing in the heavy overload resistance test has a complete theoretical derivation process, and the logic of the load spectrum meets the test requirements, which shows that the method for establishing the load spectrum of the main shaft bearing in the heavy overload resistance test has rationality.
Five, anti-large overload test design
According to the analysis of relevant data at home and abroad, the load applied by the existing hydraulic loading technology generally needs 5-10 s of stabilization time, and the specific load stabilization time is determined according to the performance of a testing machine. Although the hydraulic loading method is relatively long in application time, the load value is the same as the actual working condition, and the acting force on the main shaft bearing is the same. In addition, the periodic cycle test can be carried out on the main shaft bearing by a hydraulic loading method, the service life and the durability of the main shaft bearing are simultaneously checked, and the working state of the main shaft bearing is closer to the working state of a simulated bearing under the actual working condition. In summary, on the premise of ensuring the loading precision and stability of the test, according to the test methods described in the documents "design research of fatigue testing machine for steel cable bearing with high speed and large impact load" and "performance analysis and test research of rolling bearing for high speed spindle", the project adopts a static hydraulic loading mode. By adopting the scheme, the stress point can be well positioned, so that the main shaft bearing large overload resistance test can be repeatedly carried out for many times, and the large overload resistance performance of the main shaft bearing of the same model and the variation trend of the large overload resistance performance of the main shaft bearings of different models when the main shaft bearings are subjected to load in a unified mode can be conveniently known. But also eliminates the influence of factors such as material, process and the like on the test result. Meanwhile, the main shaft bearing test is carried out according to the national military standard of the people's republic of China "aeroengine bearing test life-determining program and requirement" (GJB7268-2011) and the national standard of the people's republic of China "rolling bearing life and reliability test and evaluation" (GB/T24607-2009).
The specific test scheme is as follows:
a) performing tester inspection according to (GJB7268-2011) 6.2.1.2;
b) after the equipment safety inspection is finished, a rotating speed sensor and a temperature sensor are installed on a test platform, and equipment debugging is carried out according to (GB/T24607-2009) 7.2;
c) a data acquisition system is built according to (GB/T24607-2009)7.3, a data line is connected, and a data storage device is used for acquiring output signals of the data acquisition system in real time;
d) setting parameters of the test bed according to the calibration parameters of the sensor and the overload requirement on a software operation interface of the upper computer at the control end;
e) after the whole test system finishes detection, a main bearing large overload resistance test program is operated, and relevant data are recorded;
f) and (GJB7268-2011) carrying out decomposition inspection on the bearing after the test according to 6.2.2.
Another embodiment of the present invention is described below with reference to the drawings.
The following is an example of the use of the method of the invention in a certain type of carrier main shaft bearing.
1. Main bearing anti-large overload test load spectrum
When a carrier-based aircraft is landed for arresting and catapulted for taking off, the aircraft needs to bear larger axial overload because the aircraft needs to be decelerated from the intermediate state to zero or accelerated from the intermediate state to the maximum state within a very short time, and fig. 2 is a change curve of the overload along with the time under the condition that the carrier landing for the aircraft is actually measured.
As can be seen from fig. 2, the maximum axial overload borne by the carrier-based aircraft during landing blocking is 5g, so that for a high-grade carrier-based trainer, the axial overload coefficient of the carrier-blocking middle state is +5g when the carrier-landing maximum state is catapulted, and the normal overload coefficient of the carrier-blocking middle state is 8g when the carrier-landing maximum state and the maximum cruising state are set.
By combining the use characteristics of a ship-based trainer and the overload coefficient of an airplane, when landing arrest and takeoff catapulting occur, the large instantaneous axial overload has great influence on the load of the bearings No. 1 and No. 3, so that the bearings are required to have enough load change resistance. Therefore, the test method focuses on the large overload test method of No. 1 and No. 3 main bearings.
2. Radial load of main bearing
The radial load borne by the main bearing of the aircraft engine is mainly the load generated by maneuvering overload and residual unbalance of a rotor, the stress condition of a subsystem under the actual working condition is considered, the radial overload coefficient of the engine is selected to be the maximum value, the overload coefficient is 8g, and 4 typical working states are selected: a slow vehicle state, a maximum cruise state, a rated state, and intermediate and maximum states.
2.1 axial load of spindle bearing
When calculating the loads of the catapult takeoff state and the landing arresting state of the main bearing of the engine, the axial overload of the catapult takeoff state is-5 g, and the axial overload of the landing arresting state is +5 g.
2.2 instantaneous rate of change of axial force during heavy overload of the spindle bearing
For the instantaneous rate of change of the axial force, the definition is shown in the following formula
In the formula:
F1the axial force borne by the main shaft bearing in the middle and maximum states takes the forward direction as the forward direction;
F2the axial force borne by the main shaft bearing in the carrier landing arresting or catapult takeoff state takes the forward direction as the forward direction;
and delta t is the time from the middle and the maximum state of the engine to the time when the axial overload reaches 5g in the process of carrier landing arresting or catapult takeoff, and for the carrier-based aircraft, the time is about 1.5s, so that the delta t is 1.5 s.
The axial force change rates of the fulcrum bearings No. 1 and No. 3 are calculated as shown in table 1.
TABLE 1 instantaneous Rate of Change of axial force of the Main bearing during Carrier landing arrest and catapult takeoff
2.3 Main bearing anti-large overload test load spectrum
In the shortest time that the tester can realize load change, the landing arresting and catapult-assisted take-off states of the engine are simulated, 10 times of each cycle are carried out in a cycle period of 5h, and the analysis is integrated to determine the test spectrums of the No. 1 and No. 3 main bearings as shown in tables 2 and 3.
TABLE 21 main bearing test cycle spectrum
Bearing test cycle chart of No. 33 in table
3. Effect of transient interruption of lubricating oil on the Large overload behavior of Main bearing
For rolling bearings, the lubricating oil has at least two functions: firstly, the heat generated by rolling contact is taken away by the circulating flow of the lubricating oil so as to achieve the cooling effect; and secondly, a layer of oil film is formed between the rolling body and the raceway so as to achieve the lubricating effect. Therefore, the lubricating oil is crucial to the bearing to maintain the working performance, and the bearing is not allowed to lack lubricating oil lubrication for a long time even under light load and low rotating speed. Under the condition of oil interruption, a large amount of heat is generated between the rolling body and the inner and outer raceways due to dry friction, so that the inner and outer raceway surfaces are burned, the performance of the bearing is reduced, and large vibration response is generated, so that the bearing finally fails to cause the fault of a main engine.
The working environment of the main bearing of the aero-engine is high temperature and high rotating speed, so that lubricating oil lubrication plays an important role in maintaining the working performance of the main bearing of the aero-engine. Under the operating mode of big overload, produce bigger local stress because of transshipping the reason between rolling element and the inside and outside raceway for the contact environment between rolling element and the raceway is more abominable, and the calorific capacity is more under the conventional load condition, consequently when lubricating oil instantaneous interruption, must lead to lubricated badly, calorific capacity can not in time scatter away and finally lead to local high temperature, causes the rolling element and the surface of inside and outside raceway to appear the failure mode of burn.
4. Method for applying large overload resistance test load to main bearing
The inventor selects a hydraulic loading mode
The hydraulic loading is based on power provided by the motor, mechanical energy is converted into pressure by the hydraulic pump, hydraulic oil is pushed, the flow direction of the hydraulic oil is changed by the control valve group, so that the hydraulic cylinder is pushed to make different strokes and different directions, different action requirements of various devices are met, and the hydraulic loading has the following advantages:
(1) the stepless speed regulation and the positive and negative rotation movement of the tested bearing can be realized, the speed regulation range is wide, the low-speed performance is stable, and the dynamic response is good;
(2) the no-load starting of the motor can be realized, so that the service lives of the motor and electrical components are prolonged;
(3) the speed characteristic of the tested bearing can be set at will, so that the performance of the product under an unexpected working condition can be obtained;
(4) the hydraulic loading has the characteristics of compact volume, large loading force and stepless adjustment, can realize dynamic loading, and also has double overload protection, so that the safety of a tested piece can be protected;
(5) the hydraulic driving system has strong modularization function, and can conveniently test range and function;
(6) under the severe working environment (dusty, humid and explosion-proof), the reliability of the hydraulic transmission system is high.
In summary, for the bearing test performed at present, the hydraulic loading system is an ideal loading method.
For the large overload test of the main shaft bearing, a bearing test bed is required to meet the requirement that the loading force is continuously changed from 0 kN to 19kN, so that a mechanical loading mode cannot be selected. And because the loading force is larger and the test time is longer, the electric loading mode also does not meet the requirement. In addition, the equipment is required to be small as much as possible, so that the hydraulic loading mode is comprehensively considered and selected.
The main bearing large overload test loading simulation mode is shown in figure 1, in order to simulate the actual working condition, the main bearing of the engine can be installed on a main shaft and is pre-tightened for positioning, and the test main shaft is used for simulating the rotation of the main shaft of the actual engine so as to drive the main bearing of the engine to rotate together. The loading device is connected with the fixed ring, the oil cylinder is used for loading acting force, and the size of the applied load is remotely controlled through the control system, so that the stepless speed regulation function of the load can be realized, the effect of simulating the actual working condition is achieved, and the flexibility of the test is improved.
5. Detection requirement of main bearing large overload resistance test
Aiming at the failure mode of the main shaft bearing during working: rolling contact failure, cracking and fracture failure, slip failure, bearing wear failure, plastic deformation failure, fretting wear failure and the like, so that the detection requirements of the spindle bearing in a large overload resistance test can be obtained as follows:
(1) detecting the surfaces of the inner raceway and the outer raceway in a rolling contact failure mode, checking the appearance quality, and judging whether the peeling phenomenon occurs or not;
(2) detecting the cracks of the retainer and the surfaces of the rolling elements in the form of bearing cracking and failure;
(3) detecting surface scratches and cracks of the inner and outer ring raceways in a bearing slipping failure mode;
(4) detecting the surface wear of the rolling body and the scrap iron of the lubricating oil in a bearing wear failure mode;
(5) detecting the sizes of the inner and outer rings in a bearing plastic deformation failure mode;
before and after the bearing test is finished, the detection items are carried out and recorded.
Claims (9)
1. A ship-borne main shaft bearing impact test method is characterized by comprising the following steps:
firstly, a main shaft bearing to be tested is placed on a test platform;
step two, controlling the main shaft bearing to rotate according to a set rotating speed;
step three, applying a preset load spectrum to the main shaft bearing, operating for a certain time and measuring to obtain the state parameters of the main shaft bearing;
step four, changing the rotating speed of the main shaft bearing, and repeating the processes of the step two and the step three until all preset rotating speeds and cycle times are finished;
step five, disassembling the spindle bearing after the test is finished, and evaluating the test result;
the load spectrum is a certain load matched with a corresponding rotating speed and loaded for a certain time, and the load comprises an axial load and a radial load.
2. The impact test method for the carrier-based main shaft bearing according to claim 1, further comprising setting rotation speeds, specifically, setting rotation speeds of the main shaft bearing in slow, cruising, maximum cruising, rated, intermediate and maximum states of the aircraft, and operation time and cycle number of each rotation speed according to different states of the aircraft.
3. The impact test method for the carrier-based main shaft bearing according to claim 2, wherein when the aircraft is in the maximum state, the rotating speed, the running time and the cycle number of the main shaft bearing are added with an axial overload coefficient of 5g and a radial overload coefficient of 8g into load calculation.
4. The method of claim 1, wherein the applied axial load is calculated at each operating load condition based on the pneumatic parameters of the compressor system and turbine components, and wherein the boundary values of the maneuvering load are-5 g and +5 g.
5. The impact test method for the carrier-based main shaft bearing according to claim 4, wherein the axial load comprises rotor blade air flow static pressure axial force FjAxial force F of rotor blade airflow static pressurejThe expression of (a) is:
in the formula, Dk1The diameter of the blade tip of the inlet section of the blade; dk2The diameter of the blade tip of the outlet section of the blade; dH1The diameter of the blade root is the inlet section of the blade; dH2The diameter of the blade root is the outlet section of the blade; p1The average airflow static pressure of the inlet section of the blade is taken as the average airflow static pressure; p2The average airflow static pressure of the blade outlet section is obtained; pk1Static pressure of airflow at the blade tip of the inlet section of the blade; pk2And the static pressure of the airflow at the blade tip of the outlet section of the blade.
6. The carrier-based main shaft bearing impact test method according to claim 4, wherein the axial load comprises an axial force F generated by an airflow axial velocity on the bladevAxial force F generated by the axial velocity of the air flow on the bladevThe expression of (a) is:
Fv＝∑Qa(Ca2-Ca1) (2)
in the formula, QaIs the air flow rate; ca1The average axial velocity of the airflow at the inlet section of the blade; ca2The average axial velocity of the airflow at the outlet section of the blade.
7. The carrier-based main shaft bearing impact test method according to claim 4, wherein the axial load comprises an axial force F generated by a cavity airflow static pressure or a cavity pressure of an oil cavityQAxial force F generated by the static airflow pressure of the ring cavity or the pressure of the lubricating oil cavityQThe expression of (a) is:
in the formula, PQStatic airflow pressure or lubricating oil cavity pressure of the annular cavity; dKThe outer diameter of the annular cavity; dHThe inner diameter of the annular cavity.
8. The impact test method for the carrier-based main shaft bearing according to claim 1, wherein the applied radial load is a load generated by a maneuvering overload and a residual unbalance amount of the rotor, and is calculated according to each working state point and a corresponding rotor rotating speed, and the maximum overload coefficient is 8 g.
9. The carrier-based main shaft bearing impact test method according to claim 8, wherein the radial load comprises an unbalance force FTAnd gravity FGUnbalanced force FTAnd gravity FGThe expression of (a) is:
FT＝miω2(7)
Fc＝mjg (8)
in the formula, miThe amount of the residual unbalance of the rotor; m isjIs the rotor weight; ω is the angular velocity.
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| CN113177276A (en) * | 2021-04-27 | 2021-07-27 | 中国航发沈阳发动机研究所 | Load determination method for high-pressure shaft thrust bearing of aircraft engine |
| CN113428381A (en) * | 2021-07-29 | 2021-09-24 | 北京机电工程研究所 | Device and method for determining time period of catapult impact action of airplane suspension |
| CN113639943A (en) * | 2021-08-20 | 2021-11-12 | 中国航发贵阳发动机设计研究所 | Device and method for beam structure hysteresis test |
| CN114509262A (en) * | 2022-01-25 | 2022-05-17 | 中国铁建重工集团股份有限公司 | Acceleration test method for main bearing of heading machine |
| CN114583888A (en) * | 2022-05-07 | 2022-06-03 | 深圳市飞米机器人科技有限公司 | Novel gear motor and servo steering engine |
| CN115060448A (en) * | 2022-06-22 | 2022-09-16 | 江苏德纳精工轴承有限公司 | Bearing impact resistance test device |
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| CN113428381A (en) * | 2021-07-29 | 2021-09-24 | 北京机电工程研究所 | Device and method for determining time period of catapult impact action of airplane suspension |
| CN113639943A (en) * | 2021-08-20 | 2021-11-12 | 中国航发贵阳发动机设计研究所 | Device and method for beam structure hysteresis test |
| CN114509262A (en) * | 2022-01-25 | 2022-05-17 | 中国铁建重工集团股份有限公司 | Acceleration test method for main bearing of heading machine |
| CN114583888A (en) * | 2022-05-07 | 2022-06-03 | 深圳市飞米机器人科技有限公司 | Novel gear motor and servo steering engine |
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| CN115680902A (en) * | 2022-10-13 | 2023-02-03 | 中国航发四川燃气涡轮研究院 | Method for adjusting axial force of rotor of aircraft engine |
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