CN113814072A - Method for monitoring unbalance force of sliding bearing of supergravity centrifugal machine - Google Patents
Method for monitoring unbalance force of sliding bearing of supergravity centrifugal machine Download PDFInfo
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- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
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- B04B9/146—Unbalance detection devices
Abstract
The invention discloses a method for monitoring unbalance force of a sliding bearing of a supergravity centrifuge. The main shaft of the hypergravity centrifugal machine is respectively provided with sliding bearings at the upper part, the middle part and the lower part, the sliding bearings are provided with bearing bushes, force sensors are arranged at the bearing bushes, and a load time-course curve is acquired by the real-time force sensors in the centrifugal machine test; and establishing two coordinate systems to synthesize the total support counterforce of each sliding bearing, processing to obtain the dynamic unbalance force of the supergravity centrifuge, checking the dynamic unbalance force of the whole supergravity centrifuge and the working performance of the sliding bearing, and realizing the monitoring of the unbalance force of the sliding bearing of the supergravity centrifuge. The invention can still ensure high-precision operation and accuracy of final unbalanced load under the condition that some sensors fail, can also reflect other factors generating dynamic unbalance, ensures more stable operation and control and has wide application range.
Description
Technical Field
The invention belongs to the technical field of centrifuge rotor balance, relates to a monitoring technology of a hypergravity centrifuge, and particularly relates to a method for monitoring an unbalanced force of a sliding bearing of the hypergravity centrifuge.
Background
A high-gravity centrifuge, as a rotating device that operates at high speeds, is subjected to dynamic loads in addition to static loads, including rotational imbalances. The dynamic load causes the forced vibration of the equipment, so that the running stability and precision are reduced, the motion noise is increased, the abrasion of the motion part is accelerated, and the service life is shortened; the heavy one can not make the rotor run normally and can not reach the design index. Therefore, the method for monitoring and feeding back the unbalance of the centrifuge in the operation process in real time sensitively and reliably is an important condition for ensuring the stable operation of the supergravity centrifuge. Especially, the design index of the existing hypergravity centrifugal machine is continuously improved, the rotating speed and the load capacity of the existing hypergravity centrifugal machine are continuously increased, the mechanism for transferring the unbalanced force is more complex, and the accurate and efficient monitoring method is essential for the safe operation of the geotechnical centrifugal machine.
The main principle of the existing monitoring technology about the unbalanced load of the hypergravity centrifuge is as follows: a force sensor is arranged between a rotary operation mechanism (a rotary arm of the centrifuge) and a supporting mechanism (a main shaft of the centrifuge), when unbalanced force is generated at the end part of a rotary system, relative displacement exists between the rotary arm and the main shaft, and signals measured by the force sensor are the unbalanced force acting on two ends of the rotary arm of the centrifuge.
Utility model patent application No. CN202582809U discloses a geotechnical centrifuge unbalance force monitoring devices. The device of this patent includes a working end, a force sensor, a rotating arm support, a tension band, and a counterweight end. The working principle of the device is as follows: when the geotechnical centrifuge is in an unbalanced state, relative motion can be generated between the tension band and the rotating arm support, so that unbalanced force can be transmitted to the force sensor, and therefore unbalanced force monitoring is achieved.
The monitoring of the unbalance amount of the centrifugal machine is also an important component of a balancing system of the centrifugal machine, and a monitoring result is fed back to the balancing module, so that the safe operation of the centrifugal machine is effectively ensured.
Utility model patent application No. CN203342956U discloses a novel balanced self-interacting system of geotechnical centrifuge. The application includes a water tank, a load cell, a control valve, and a controller. The working principle of the regulating system is as follows: after the load of the working end of the centrifuge is increased, the sensor measures out the unbalanced force, the electromagnetic switch valve in the control valve is opened, water is injected into the water tank, and the electromagnetic switch valve is closed and stops injecting water until the unbalanced force is close to zero.
The invention patent application No. CN109092575A discloses a balancing device and a balancing method of a centrifugal machine based on rotation center position adjustment. The unbalanced force monitoring module in the application balancing system comprises a controller, a motion executing mechanism A, a motion executing mechanism B, a force sensor A and a force sensor B, wherein two ends of the sensor are respectively connected with the motion executing mechanism (a rotating arm support) and a rotating arm. The main working principle is as follows: when the centrifugal machine rotates, different values can be measured between the force sensors A and B due to unbalanced centrifugal force action of the two end parts, and the feedback result is used as the basis for judgment of the balancing system.
The patent application of invention No. CN109876931B discloses a monitoring method for unbalance amount of a supergravity centrifuge. A plurality of force sensors are arranged on foundation bolts used for fixing a transmission support of the hypergravity centrifugal machine at a base of the hypergravity centrifugal machine, the force sensors are arranged along a circumferential array, a relation curve between the load of the foundation bolts and the unbalanced force of the hypergravity centrifugal machine is obtained through a calibration test, and then the unbalanced force is obtained through indirect conversion of the calibration curve during an actual test.
The main defects of the unbalance monitoring method of the existing hypergravity centrifuge are as follows:
the monitoring device is required to be arranged between the rotating arm and the rotating arm support, and the newly-added mechanism not only increases the complexity of the main structure, but also has complex processing, troublesome installation and adjustment and limited measurement precision and limits the development of the self-technology. In addition, the balancing technology mainly utilizes the monitoring result of the unbalance amount monitoring device to feed back and control the moving mechanism to carry out balancing operation in real time, and if the additional mechanism is not well adjusted, the friction force additionally added to the centrifugal machine can influence the transmission of the unbalance force to cause the deviation of monitoring data.
In addition, the existing monitoring technology represents the unbalance amount which represents the unbalanced centrifugal force of the working end and the counterweight end through the measurement result of the force sensor between the rotating arm and the main shaft, but the monitoring result is deviated to be unsafe due to overcoming the action of the friction force between the rotating arm support and the rotating arm. Furthermore, the amount of unbalance to be borne by the centrifugal machine due to other reasons (such as swing carry-over angle, installation deviation, etc.) cannot be monitored by the prior art.
Finally, the dynamic unbalance load obtained through indirect conversion cannot reflect the effect of the unbalance force at the end part of the rotating arm on the bearing, and the bearing is a key supporting component related to the safe and effective operation of the supergravity centrifuge and is also a main component in a mechanical system, so that the real-time performance of the dynamic load and the stability of the machine operation can be ensured only by a direct unbalance force monitoring method based on the bearing, which is not solved by the existing indirect monitoring methods.
Disclosure of Invention
The invention aims to solve the technical problems in the background art, and provides a method for monitoring the unbalance force of a sliding bearing of a supergravity centrifugal machine, which is used for obtaining accurate dynamic unbalance load based on real-time monitoring of bearing stress and feeding back the reliability of the efficacy of a system component by a monitoring value.
The technical scheme adopted by the invention is as follows:
firstly, sliding bearings are respectively arranged at the upper part, the middle part and the lower part of a main shaft of the hypergravity centrifugal machine, each sliding bearing is provided with a different number of bearing bushes, force sensors are arranged at the bearing bushes of different sliding bearings,
secondly, performing a centrifuge test, collecting load force data of a force sensor on a bearing bush of each sliding bearing in real time, wherein the force sensor provides counter-force measurement to obtain a load time-course curve;
establishing two coordinate systems of a bearing bush system local polar coordinate system and a centrifuge integral Cartesian coordinate system, and synthesizing the total support counterforce of each sliding bearing according to a load time course curve and the set coordinate system;
the bearing bush system local polar coordinate system is used for determining the position of each bearing bush, and the centrifuge integral Cartesian coordinate system is used for determining the total support reaction force of the sliding bearing and synthesizing the dynamic unbalance force.
Step four, obtaining the dynamic unbalance force of the supergravity centrifuge according to the real-time total support counter force of each sliding bearing;
and fifthly, checking the dynamic unbalance force of the whole supergravity centrifugal machine and the working performance of the sliding bearing, and monitoring the unbalance force of the sliding bearing of the supergravity centrifugal machine.
In the third step of the method, the first step,
each sliding bearing establishes the same bearing bush system local polar coordinate system: the method comprises the following steps that the bearing bushes of a sliding bearing bush system are uniformly distributed along the circumference of a main shaft at intervals, the number of any one bearing bush is selected to be 1, the number of the rest bearing bushes are sequentially selected to be 2,3 and 4 … according to the anticlockwise direction, the circle center of the cross section of the main shaft is selected to be the origin of a polar coordinate system, the direction from the origin to the bearing bush No. 1 is specified to be the polar axis direction of the polar coordinate system and is marked as an x axis, and the anticlockwise rotating angle of the polar coordinate system is used as the positive direction of the angle of the coordinate system; in this way the x-axis of the local coordinate system of the bearing system at different slide bearings is set to one direction. The total of N force sensors for each bearing pad in the plain bearing are numbered 1,2,3 … N in a counter clockwise or clockwise sequence.
Setting an integral Cartesian coordinate system of the hypergravity centrifugal machine: the origin of the whole Cartesian coordinate system of the centrifuge is selected to be the circle center of the cross section of the lower sliding bearing, the X axis of the whole Cartesian coordinate system of the centrifuge is coincident with the X axis of the local polar coordinate system of the sliding bearing bush system, the Z axis of the whole Cartesian coordinate system of the centrifuge is coincident with the central line of the main shaft of the centrifuge, the direction is the direction in which the lower sliding bearing points to the upper sliding bearing, and the Y axis of the whole Cartesian coordinate system of the centrifuge is uniquely determined by the Z axis and the X axis through a right-hand rule.
In the second step, each load time-course curve is that the force monitored by the force sensor continuously changes along with the time tCurve of (a), expressed as qi(t)。
In the third step, the following processing is carried out for each sliding bearing to obtain the total support reaction force of each sliding bearing:
synthesizing the total support reaction force of the sliding bearing according to the load time-course curve of the force sensor on each bearing bush in the sliding bearing:
wherein Q (t) represents a total seat reaction force of the sliding bearing, QX(t) component of total seating reaction force of the slide bearing in the X direction in the Cartesian coordinate system of the centrifuge as a whole, QY(t) represents a component of the total seating reaction force of the slide bearing in the Y direction in the overall cartesian coordinate system of the centrifuge; i denotes the number of force sensors on the pads at the plain bearing, N denotes the total number of force sensors on the pads at the plain bearing, such as N-N at plain bearing a, M at the seat of middle plain bearing B, L at the upper plain bearing C, N, M, L denotes the total number of pads in the upper, middle and lower plain bearings, respectively, i.e. the total number of force sensors; etaiRepresenting the angle through which the force sensor at the ith bearing shell in the sliding bearing rotates in the local polar coordinate system of the bearing shell system, where eta is alpha, beta,
α、β、
respectively representing the deflection angles of the upper sliding bearing, the middle sliding bearing and the middle bearing bush of the lower sliding bearing, namely the deflection angle of the force sensor; gamma rayQThe azimuth angle of the total support reaction force in the coordinate system of the integral centrifuge can be gamma of the lower sliding bearingAGamma of plain bearingBOr gamma of upper slide bearingsC(ii) a t represents time;
thus, the total seating reaction forces obtained by the sliding bearings of the lower, middle and upper portions of the main shaft are respectively represented by QA(t)、 QB(t)、QC(t) wherein QA(t) represents the total seating reaction force of the lower slide bearing, QB(t) represents the total seating reaction force of the plain bearing in the middle, QC(t) represents the total abutment reaction force of the upper slide bearing.
In the fourth step, the dynamic unbalance force f (t) of the supergravity centrifuge is obtained according to the real-time total support reaction force q (t) of the three sliding bearings, and is expressed as follows:
QA(t)+QB(t)+QC(t)＝F(t)
wherein Q isA(t)、QB(t)、QC(t) represents total seating reaction forces obtained by the sliding bearings at the lower, middle and upper portions of the main shaft, respectively.
In the present invention, although the total seat reaction force of the three sliding bearings is a temperature-dependent quantity, the final dynamic unbalance force is a temperature-independent system quantity, and the temperature becomes an internal variable of the system and is equally cancelled by the three sliding bearings.
In the fifth step, the method specifically comprises the following steps:
and (3) establishing the following matrix relation according to the result of the total support reaction force Q (t) of the three sliding bearings obtained in the step three:
then, the dynamic balance force f (t) obtained in step four is checked by the following judgment formula:
F1(t)＝F2(t)＝F3(t)＝F(t)
wherein, F1(t) shows the dynamic unbalance force, F, calculated from the total bearing reaction forces of the lower and middle sliding bearings2(t) shows the dynamic unbalance force calculated from the total bearing reaction forces of the middle and upper plain bearings, F3(t) represents the dynamic unbalance force calculated by the total bearing reaction force of the lower and upper sliding bearings; kpqIs a coefficient matrix determined by the distance between the rotating arm and three sliding bearings of the hypergravity centrifuge, wherein p, q is 1,2,3, p, q all represent the serial numbers of the sliding bearings, and are respectively calculated as follows:
wherein L isBIndicating the length of the middle plain bearing from the lower plain bearing, LCIndicating the length of the upper slide bearing from the lower slide bearing, LFThe length of a dynamic unbalance force action line from the lower sliding bearing is shown, namely the length of a rotating arm of the centrifuge from the lower sliding bearing of the support;
due to the three sliding bearings, the three expressions are listed in a pairwise combination mode, and the three calculated values are expressed, theoretically, the three calculated values are consistent when the system works normally.
If the judgment formula of the dynamic balance force F (t) is satisfied, namely three equal signs in the judgment formula are all satisfied, the dynamic unbalance force derived by moment balance is equal to the dynamic unbalance force synthesized by direct support counter force (including the equal magnitude and direction), and the dynamic unbalance force synthesis is correct; the system components operate normally.
If the judgment formula of the dynamic balance force F (t) is not established, namely, if one equal sign in the judgment formula is not established, the problem occurs to a bearing bush with a certain sliding bearing transmitting force or a certain force sensor, so that the dynamic balance force is synthesized to generate deviation, early warning is carried out, the evolution condition of the working performance of the bearing bush of the bearing can be obtained according to long-term monitoring amount, the parts of three sliding bearings or the force sensors on the bearing bush are overhauled according to the deviation phenomenon indication, and the overload operation of the mechanism is avoided in time.
The hypergravity centrifugal machine comprises a main shaft, a rotating arm and a hanging basket; the main shaft of the supergravity centrifugal machine is provided with an upper sliding bearing, a middle sliding bearing and a lower sliding bearing at the upper part, the middle part and the lower part respectively; the upper sliding bearing, the middle sliding bearing and the lower sliding bearing are all provided with bearing bushes
The upper sliding bearing, the middle sliding bearing and the lower sliding bearing are the same in structure and respectively comprise a bearing bush, a bearing bush mounting bracket, a supporting rack and a force sensor; the support frame is fixedly installed on the inner wall of an external hypergravity centrifuge chamber, the support frame is arranged around the main shaft in an annular mode, a plurality of bearing bushes are arranged between the main shaft and the support frame along the circumferential interval, the bearing bushes are uniformly distributed at the same circumference interval, each bearing bush is connected with the support frame through a bearing bush mounting support in a mounting mode, and a force sensor is installed between the outer side face of each bearing bush and the support frame in a pressing mode.
The method reflects the stress condition of the support in real time through a force sensor on a bearing bush of the sliding bearing, further determines the magnitude and the direction of the total support reaction force of each support, then synthesizes the dynamic unbalance force of the system, and simultaneously provides an indirect method for checking the dynamic unbalance load.
The invention has the beneficial effects that:
the invention reflects the bearing stress condition in real time through the force sensor on the sliding bearing bush of the hypergravity centrifuge, further determines the magnitude and the direction of the total bearing counterforce of each bearing, then synthesizes the dynamic unbalance force of the system, and simultaneously provides an indirect method for checking the dynamic unbalance load.
Firstly, the method of the invention realizes the purpose of monitoring the reaction force change of the support in the whole process based on the working performance of the sensor, and further synthesizes the dynamic unbalance force, and the provided indirect checking method can ensure the reliability and stability of the final measured value, and even under the condition that some sensors fail, the monitoring system can still ensure the high-precision operation, thus having good robustness.
Secondly, the method for monitoring the unbalanced force directly based on the bearing can reflect the effect of the unbalanced force at the end part of the rotating arm on the bearing, and can accurately capture the real-time property of dynamic load change and the change of the performance of a sliding bearing bush, thereby fully ensuring the running safety of the hypergravity centrifuge.
And then, the requirement that auxiliary monitoring equipment needs to be installed in the existing method is overcome, and the dependence on foreign objects is reduced, because the unbalanced force firstly acts on the bearing and then is transmitted to each part such as a support, the stability of the monitoring precision is ensured by a direct method, and the dangerous working condition of underestimated load cannot be caused.
Finally, other factors generating dynamic unbalance can be reflected, stable operation and control of the machine are guaranteed, the requirements of the high precision and the high stability of the supergravity centrifugal machine are fully met, and the supergravity centrifugal machine is wide in application range, strong in scientificity, simple and easy to implement.
Drawings
FIG. 1 is a schematic diagram of the basic construction of a supergravity centrifuge;
FIG. 2 is a schematic view of the location and installation of a sensor on a bushing of a sliding bearing;
FIG. 3 is a schematic diagram of the arrangement of the bearing bush system and the sensor at different sliding bearings in the embodiment;
FIG. 4 is a time-course graph of a force sensor on a bearing shell of the lower slide bearing A in an embodiment;
in the figure: the device comprises a main shaft (1), a rotating arm (2), a hanging basket (3), a bearing bush (4), a bearing bush mounting bracket (5), a supporting rack (6) and a force sensor (7); comprises an upper sliding bearing (C), a middle sliding bearing (B) and a lower sliding bearing (A).
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
The embodiment of the invention and the implementation process thereof are as follows:
as shown in fig. 1, the supergravity centrifuge includes a main shaft 1, a rotor arm 2, and a basket 3; an upper sliding bearing C, a middle sliding bearing B and a lower sliding bearing A are respectively arranged at the upper part, the middle part and the lower part of a main shaft 1 of the supergravity centrifugal machine; the upper sliding bearing C, the middle sliding bearing B and the lower sliding bearing A are all provided with bearing bushes 4.
As shown in fig. 2, the upper sliding bearing C, the middle sliding bearing B and the lower sliding bearing a have the same structure, and each of them includes a bearing bush 4, a bearing bush mounting bracket 5, a supporting frame 6 and a force sensor 7; support frame 6 fixed mounting is in outside hypergravity centrifuge chamber inner wall, and support frame 6 arranges for the annular around main shaft 1, has a plurality of axle bushes 4 along circumference interval arrangement between main shaft 1 and the support frame 6, and a plurality of axle bushes 4 are at same circumference interval equipartition, and every axle bush 4 is through axle bush installing support 5 and support frame 6 erection joint, and it has a force transducer 7 to compress tightly to install between 4 lateral surfaces of every axle bush and the support frame 6.
Firstly, two coordinate systems are established according to the characteristics of the structure of the hypergravity centrifuge and the composition of the sliding bearing, and one coordinate system is a local polar coordinate system of the sliding bearing bush system. Specifically, one of the total 8 bearing bushes of the bearing bush system uniformly distributed on the lower sliding bearing a is designated as 1, the rest bearing bushes are sequentially designated as 2 and 3 … 8 in a counterclockwise direction, the center of the cross section of the main shaft is selected as the origin of the polar coordinate system, the direction from the origin o to the bearing bush 1 is set as the polar axis direction of the polar coordinate system and is designated as the x axis, the angle of the local polar coordinate rotated counterclockwise from the x axis is designated as alpha, the bearing bush system local polar coordinate system which is the same as that of the lower sliding bearing a is established for the centering sliding bearing B (containing 12 bearing bushes) and the upper sliding bearing C (containing 8 bearing bushes), the bearing bush deflection angle of the centering sliding bearing B is designated as beta, and the bearing bush deflection angle of the centering sliding bearing B, namely the deflection angle of the force sensor is designated as beta
Finally, the three-position sliding bearing bush system local polar coordinate system shown in fig. 3 is presented, the bushes are uniformly distributed along the circumference at intervals, and each bush is provided with a force sensor, so that the position of each bush and the force sensor thereof can be uniquely determined in the sliding bearing through the local polar coordinate system. And the other is to establish a whole Cartesian coordinate system of the hypergravity centrifuge, specifically, the origin of the coordinate system is selected as the center of a cross section of the lower sliding bearing A, namely, the center of the cross section of the lower sliding bearing A coincides with the origin o of a local polar coordinate system of a bearing bush system of the lower sliding bearing, the X axis of the whole Cartesian coordinate system of the centrifuge is specified to coincide with the X axis of the local polar coordinate system of the bearing bush system of the lower sliding bearing A, the central line of a main shaft is selected as the Z axis of the whole Cartesian coordinate system, and the direction is the direction in which the lower sliding bearing A points to the upper sliding bearing C, so that the Y axis of the whole Cartesian coordinate system of the centrifuge can be uniquely determined according to the right-hand rule.
Secondly, during the actual engine-rotating test, the load time-course curve of the sensor on each bearing bush is monitored and recorded in real time, the curve is a quantity which continuously changes along with the time t and is expressed as qiAnd (t) synthesizing the real-time total support reaction force of the sliding bearing according to the time curve of the force sensor. For example, force sensors are arranged on 8 bearing bushes of the lower sliding bearing A, and the rotary machine is operated to a certain time t0In which 4 sensors are pressed to provide additional counter-force, the load time course of these sensors is shown in fig. 4, t0Sensor magnitude at time q0. Two components Q of the total support counterforce of the lower sliding bearing A under the whole Cartesian coordinate system can be synthesized according to the positions and deflection angles of the four sensors of the lower sliding bearing A in the local coordinate system of the bearing bush system and the positive and negative meanings of the load value of the force sensor under the whole Cartesian coordinate systemAX(t0) And QAY(t0) And a final value QA(t0) Calculated according to the following formula:
in the formula, QA(t0) Represents t0Total seating reaction force, Q, of sliding bearing A at all timesAX(t0) Represents t0X component, Q, of the total seating reaction of the sliding bearing a at any moment in the overall cartesian coordinate systemAY(t0) Represents t0A Y component of the total support reaction force of the sliding bearing A under the overall Cartesian coordinate system at any moment; table 1 below shows the calculation of the two components of the total abutment reaction force of the lower slide bearing a, so that the total abutment reaction force value of the lower slide bearing a is 874.22kN and the azimuth angle is 215.6 ° by the combined calculation, and the total abutment reaction force and the azimuth angle of the middle slide bearing B and the upper slide bearing C can be obtained by the same procedure.
TABLE 1
And then, further obtaining real-time dynamic unbalance force of the hypergravity centrifugal machine according to the total support reaction force and the azimuth angle of the three calculated and synthesized sliding bearings. E.g. t obtained as described above0The total bearing reaction force of the sliding bearing at the moment is t0The dynamic unbalance force of the supergravity centrifuge at the moment is calculated according to the following formula:
QA(t0)+QB(t0)+QC(t0)＝F(t0)
because the positive and negative of different quantities in the whole Cartesian coordinate system of the centrifuge have definite meanings, the final result can be obtained by direct algebraic summation, the calculation result is shown in the table 2, and finally the final result is t0Dynamic unbalance force F (t) at time0) The value was 979.76 kN.
TABLE 2
And finally, checking the dynamic unbalance force obtained by the calculation through an indirect method. For example, according to t already obtained previously0The counter force and the dynamic unbalance force of the total support of the three sliding bearings at any moment are calculated in two steps according to the following matrix formula:
F1(t0)＝F2(t0)＝F3(t0)＝F(t0)
wherein, Fk(t0) (k ═ 1,2,3) are all t indirectly calculated from two of the total bearing reaction forces of the three sliding bearings that have been combined0Moment dynamic unbalance force, matrix coefficient Kpq(p, q ═ 1,2,3) is based on the lower slide bearing a, the middle slide bearing B, the upper slide bearing C and the tumbler imbalance force F (t)0) The action lines, i.e. the relative position relationship between the center lines of the rotor arms, are calculated, for example, the geometric relationships between the three sliding bearings of the supergravity centrifuge and the action lines of the unbalance force are respectively: l isB＝1.9m，LC＝8.5m，LF5.06m, then each coefficient is calculated as follows:
substituting the coefficient and the synthesized total bearing reaction force of the sliding bearing into a matrix relation, and calculating the dynamic unbalance force as follows:
F1(t0)＝2.4709×874.56-1.92×615.3＝979.764
F2(t0)＝-0.375×615.3+1.68×720.5＝979.763
F3(t0)＝-0.601266×874.56+2.08861×720.5＝979.761
and then checking according to the judgment relation:
F1(t0)＝F2(t0)＝F3(t0)＝F(t0)
by the above checking calculation, t0And three equal signs are all established at the moment, so that the calculation result of judging the dynamic unbalance force is reliable. If the difference between the two results is larger, or an equal sign is not established, the performance fault of the bearing bush of the sliding bearing or the force sensor on the bearing bush is proved to be generated, and further maintenance is needed, so that the efficacy of the component can be fed back in the checking process, and early warning is carried out according to the deviation phenomenon of the result, so that the component is maintained, and the potential risk caused by overload operation of the mechanism is avoided in time. The above examples specifically give t0The calculation logic and the result explanation of the time are that the real-time monitoring, calculation and check are carried out according to the same principle and steps at each time of the whole process of the centrifuge test.
Therefore, the method disclosed by the invention can be used for directly realizing the purpose of monitoring the change of the counter force of the sliding bearing in the whole process based on the working performance of the sensor on the sliding bearing bush, even under the condition that some sensors fail, the monitoring system can still ensure high-precision operation and the accuracy of final unbalanced load, the method for directly measuring the bearing stress cannot cause the occurrence of dangerous working conditions of underestimated load, and other factors for generating dynamic unbalance can be reflected, so that the stable operation and control of the machine are more ensured, the application range is wide, the scientificity is strong, and the method is simple and easy to implement.
Claims (8)
1. A method for monitoring the unbalance force of a sliding bearing of a supergravity centrifuge is characterized by comprising the following steps: the method comprises the following steps:
firstly, sliding bearings are respectively arranged at the upper part, the middle part and the lower part of a main shaft (1) of the hypergravity centrifugal machine, each sliding bearing is provided with a bearing bush, force sensors are arranged at the bearing bushes of different sliding bearings,
step two, carrying out a centrifuge test, and acquiring load force data of a force sensor on a bearing bush of each sliding bearing in real time to obtain a load time-course curve;
establishing two coordinate systems of a bearing bush system local polar coordinate system and a centrifuge integral Cartesian coordinate system, and synthesizing the total support counterforce of each sliding bearing according to a load time course curve and the set coordinate system;
step four, obtaining the dynamic unbalance force of the supergravity centrifuge according to the real-time total support counter force of each sliding bearing;
and fifthly, checking the dynamic unbalance force of the whole supergravity centrifugal machine and the working performance of the sliding bearing, and monitoring the unbalance force of the sliding bearing of the supergravity centrifugal machine.
2. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: in the third step of the method, each sliding bearing establishes the same bearing bush system local polar coordinate system: the method comprises the following steps that the bearing bushes of a sliding bearing bush system are uniformly distributed along the circumference of a main shaft at intervals, the number of any one bearing bush is selected to be 1, the number of the rest bearing bushes are sequentially selected to be 2,3 and 4 … according to the anticlockwise direction, the circle center of the cross section of the main shaft is selected to be the origin of a polar coordinate system, the direction from the origin to the bearing bush No. 1 is specified to be the polar axis direction of the polar coordinate system and is marked as an x axis, and the anticlockwise rotating angle of the polar coordinate system is used as the positive direction of the angle of the coordinate system; setting an integral Cartesian coordinate system of the hypergravity centrifugal machine: the origin of the whole Cartesian coordinate system of the centrifuge is selected to be the circle center of the cross section of the lower sliding bearing, the X axis of the whole Cartesian coordinate system of the centrifuge is coincident with the X axis of the local polar coordinate system of the sliding bearing bush system, the Z axis of the whole Cartesian coordinate system of the centrifuge is coincident with the central line of the main shaft of the centrifuge, the direction is the direction in which the lower sliding bearing points to the upper sliding bearing, and the Y axis of the whole Cartesian coordinate system of the centrifuge is uniquely determined by the Z axis and the X axis through a right-hand rule.
3. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: in the second step, each load time-course curve is a curve of the force monitored by the force sensor changing along with the time t and is expressed as qi(t)。
4. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: in the third step, the following processing is carried out for each sliding bearing to obtain the total support reaction force of each sliding bearing: synthesizing the total seat reaction force of the sliding bearing according to the load time course curve of a force sensor (7) on each bearing bush in the sliding bearing:
wherein Q (t) represents a total seat reaction force of the sliding bearing, QX(t) component of total seating reaction force of the slide bearing in the X direction in the Cartesian coordinate system of the centrifuge as a whole, QY(t) represents a component of the total seating reaction force of the slide bearing in the Y direction in the overall cartesian coordinate system of the centrifuge; i denotes the ordinal number of the force sensors on the bearing shell at the slide bearing, n denotes the total number of force sensors on the bearing shell at the slide bearing, ηiRepresenting the angle, gamma, over which the force sensor (7) at the ith bearing shell of the plain bearing rotates in a local polar coordinate system of the bearing shell systemQRepresenting the azimuth angle of the total support counterforce in the coordinate system of the integral centrifuge; t represents time.
5. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: in the fourth step, the dynamic unbalance force f (t) of the supergravity centrifuge is obtained according to the real-time total support reaction force q (t) of the three sliding bearings, and is expressed as follows:
QA(t)+QB(t)+QC(t)＝F(t)
wherein Q isA(t)、QB(t)、QC(t) represents total seating reaction forces obtained by the sliding bearings at the lower, middle and upper portions of the main shaft (1), respectively.
6. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: in the fifth step, the method specifically comprises the following steps:
and (3) establishing the following matrix relation according to the result of the total support reaction force Q (t) of the three sliding bearings obtained in the step three:
then, the dynamic balance force f (t) obtained in step four is checked by the following judgment formula:
F1(t)＝F2(t)＝F3(t)＝F(t)
wherein, F1(t) shows the dynamic unbalance force, F, calculated from the total bearing reaction forces of the lower and middle sliding bearings2(t) shows the dynamic unbalance force calculated from the total bearing reaction forces of the middle and upper plain bearings, F3(t) represents the dynamic unbalance force calculated by the total bearing reaction force of the lower and upper sliding bearings; kpqIs a coefficient matrix determined by the distance between the rotating arm and three sliding bearings of the hypergravity centrifuge, wherein p, q is 1,2,3, p, q all represent the serial numbers of the sliding bearings, and are respectively calculated as follows:
wherein L isBShowing the length of the middle sliding bearing (B) from the lower sliding bearing (A), LCIndicates the length, L, of the upper slide bearing (C) from the lower slide bearing (A)FThe length of a dynamic unbalance force action line from the lower sliding bearing (A), namely the length of a rotating arm of the centrifuge from the lower sliding bearing (A) of the support is shown;
if the judgment formula of the dynamic unbalance force F (t) is satisfied, the dynamic unbalance force synthesis is correct;
if the judgment formula of the dynamic balance force F (t) is not established, the problem occurs to a bearing bush or a force sensor of a certain sliding bearing transferring force, so that the dynamic unbalance force is synthesized to generate deviation, early warning is carried out, parts of three sliding bearings or the force sensors on the bearing bushes are overhauled according to the deviation phenomenon indication, and overload operation of the mechanism is avoided in time.
7. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 1, wherein: the main shaft (1) of the supergravity centrifugal machine is provided with an upper sliding bearing (C), a middle sliding bearing (B) and a lower sliding bearing (A) at the upper part, the middle part and the lower part respectively; the upper sliding bearing (C), the middle sliding bearing (B) and the lower sliding bearing (A) are all provided with bearing bushes (4).
8. The method for monitoring the unbalance force of the sliding bearing of the supergravity centrifuge according to claim 5, wherein: the upper sliding bearing (C), the middle sliding bearing (B) and the lower sliding bearing (A) have the same structure and respectively comprise a bearing bush (4), a bearing bush mounting bracket (5), a supporting rack (6) and a force sensor (7); the supporting frame (6) is fixedly installed, the supporting frame (6) is arranged on the outer periphery of the main shaft (1) in an annular mode, a plurality of bearing bushes (4) are arranged between the main shaft (1) and the supporting frame (6) at intervals along the circumferential direction, each bearing bush (4) is connected with the supporting frame (6) through a bearing bush mounting bracket (5) in a mounting mode, and a force sensor (7) is installed between the outer side face of each bearing bush (4) and the supporting frame (6) in a pressing mode.
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