CN108120574A - Method for monitoring looseness of pipe threaded joint - Google Patents
Method for monitoring looseness of pipe threaded joint Download PDFInfo
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- CN108120574A CN108120574A CN201810108140.9A CN201810108140A CN108120574A CN 108120574 A CN108120574 A CN 108120574A CN 201810108140 A CN201810108140 A CN 201810108140A CN 108120574 A CN108120574 A CN 108120574A
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- pipe screw
- signal
- pipe
- screw thread
- monitoring
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/40—Investigating fluid-tightness of structures by using electric means, e.g. by observing electric discharges
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- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Examining Or Testing Airtightness (AREA)
Abstract
The invention discloses a method for monitoring the looseness of a pipe threaded joint, which is characterized in that piezoelectric ceramic chip sensors are respectively stuck on the surfaces of a threaded pipe and a threaded joint of a pipe thread, firstly, an excitation electric signal is used for exciting one piezoelectric ceramic chip sensor, a piezoelectric stress wave signal generated by the sensor is transmitted through a contact surface between the threaded pipe and the threaded joint in the pipe thread, then, the piezoelectric stress wave signal is captured by the other piezoelectric ceramic chip sensor, converted into an electric signal and collected by an NI signal acquisition card, and the sealing state of the measured pipe thread at the moment is judged and identified by comparing and analyzing the difference between the received signal and the reference value of the received signal in the normal sealing state. The invention applies the piezoelectric ceramic sensor technology, can simply and conveniently realize the monitoring and the identification of the sealing state (loosening and leakage) of the pipe thread, greatly improves the safety of the pipe thread connection, reduces the potential safety hazard and the operation risk, improves the overall economic benefit and generates positive significance.
Description
Technical field
The present invention relates to structural health monitoring technology fields, are related to a kind of be threadedly coupled and loosen monitoring, and in particular to is a kind of
The monitoring method loosened for pipe screw joint.
Background technology
Centering, guiding role are good when inner and outer pipe screw thread be combined with each other, and assembling, convenient disassembly can bear larger axial force
And torque, it is widely used in the connection of small-medium size pipe-line system.Pipe screw thread work when, be subject to for a long time various external loads and
Effect of vibration influences, if lacking timely and effectively repair and maintenance, pipe screw joint position often generates loosening and close to its
Envelope property causes larger destruction, therefore the loosening leakage problem for how solving pipe screw joint in the pipeline of seal request is long-term
Since it is of interest by people always.
Piezoelectric ceramics (Lead Zirconate Titanate, PZT) is with its distinctive sensing and actuator function and as near
In one of intellectual material that the fields such as aerospace, the energy, machinery, building structure are widely studied and apply over year.It is because having
Response is fast, wide frequency range, easily cut, lower-price characteristic and there is huge applications in terms of engineering structure monitoring to dive
Power.
The content of the invention
The technical problem to be solved by the present invention is to loosen the blank in monitoring field for pipe screw joint, propose a kind of use
The monitoring method of disease is loosened in pipe screw thread, accurately monitoring and identification can be carried out in real time to the loosening of pipe screw joint.
In order to solve the above technical problems, the technical solution adopted in the present invention is：
A kind of monitoring method loosened for pipe screw joint, which is characterized in that this method comprises the following steps：
Two piezoceramic transducers are fixed on nipple and screw thread by step 1 in a manner of surface mount respectively
The surface of pipe carries out waterproof insulation process on piezoceramic transducer surface；
Two piezoceramic transducers are connected to data collecting card by cable respectively, then adopt data by step 2
Truck is connected with computer for analysis terminal；
Step 3, computer for analysis terminal control the excitation electric signal of the certain frequency range of data collecting card generation by cable, and
It is exported by data collecting card output terminal, is transferred to the piezoceramic transducer as driver through cable, excitation electric signal drives
Dynamic piezoceramic transducer generates mechanical oscillation, forms piezoelectric stress ripple in pipe screw thread connection, and is propagated along duct orientation；Separately
One piezoceramic transducer receives the piezoelectric stress ripple signal transferred by pipe screw thread connection and is converted as receiver
For electric signal, the input terminal of data collecting card is transferred to through cable, data collecting card will be as the piezoelectric ceramics of receiver sensing
The electric signal of device output is converted into digital signal, and is transferred to computer for analysis terminal；
Step 4, under the normal seal operation state of the pipe screw thread defined in computer analysis system, measured conduct receives
The piezoceramic transducer signal of device builds identification feature parameter reference value, afterwards by monitoring follow-up clothes as reference signal
The identification feature parameter of different times pipe screw thread connection measuring signal under labour state, by identification feature parameter and identification feature parameter
A reference value comparative analysis and the loosening judging quota for calculating pipe screw joint draw pipe screw thread by the variation for monitoring judging quota
The sealing situation of connector.
As an improvement, in step 4, the piezoceramic transducer under the normal seal operation state of pipe screw thread as receiver
Reference signal, take pipe screw thread installation is complete the acquisition signal at initial stage of coming into operation or by prior art detection side
When method confirms that pipe screw thread does not have to loosen leakage, the signal of experiment acquisition is carried out.
As an improvement, in step 4, identification feature parameter is that can characterize the direct measured value of signal characteristic or spread out
Raw value.
As an improvement, the identification feature parameter includes receiving energy magnitude, wavelet-packet energy value, the structure partial of signal
A kind of or arbitrarily several combinations in resonant frequency, signal fitting regression coefficient, factorial analysis coefficient and small echo packet node coefficient.
As an improvement, loosen the signal characteristic value of judging quota including above-mentioned identification feature parameter relative changing value and/or
Change relative mean square deviation, defined loosening judging quota is bigger, then shows that the service state of tested pipe screw joint is more normal
Sealing state difference is more apparent, i.e. the possibility of generation loosening leakage is bigger, and it is more serious to loosen disease.
As an improvement, in step 1, epoxy resin is uniformly smeared on piezoceramic transducer surface, is carried out at waterproof insulation
Reason.
As an improvement, the data collecting card is NI data acquisition cards, NI data acquisition cards are by BNC cables respectively with two
A piezoceramic transducer is connected, and NI data acquisition cards are connected by USB cable with computer for analysis terminal.
As an improvement, the computer for analysis terminal is encouraged by the excitation electric signal that data collecting card generates for sine sweep
Electric signal.
The beneficial effects of the present invention are piezoceramic transducer technology is applied to pipe screw joint working condition (or
Loosen disease) monitoring and identification, definite principle, of low cost, operation is simple, identification is accurate, can realize pipe screw thread
The long-term on-line monitoring of seal operation state and identification, the generation of leakage disease is loosened for reducing pipe screw joint, is reduced whole
The monitoring of a pipe-line system and operation expense, science is judged and the military service safety and remaining life of prediction pipe screw thread, ensures
The safe and efficient operating of entire pipe screw thread system engineering, safeguards the security of the lives and property of numerous people, will generate positive meaning.
In addition the present invention only leads to piezoceramic transducer without carrying out specific customization to pipe screw joint to be monitored
It crosses bonding method to be fixed on existing pipe screw joint, convenient and efficient, use cost is cheap.
Description of the drawings
Attached drawing 1 arranges schematic diagram for the pipe screw thread connection of the present invention and piezoceramic transducer.
Attached drawing 2 is that the pipe screw thread of the present invention loosens status monitoring schematic diagram.
Attached drawing 3 is that pipe screw thread is connected to thread contact area reduction contrast schematic diagram under sealing and loosening state；
Wherein Fig. 3 a connect sealing state schematic diagram for pipe screw thread, and Fig. 3 b connect schematic diagram under loosening state for pipe screw thread.
Attached drawing 4 is two piezoceramic transducer relative position change schematic diagrams under pipe thread seal and loosening state.
In figure：1- screwed pipes, 2- nipples, 3- piezoceramic transducers, 4- piezoceramic transducers, 5-BNC cables,
6-NI data acquisition cards, 7-USB cables, 8- computer for analysis terminals.
Specific embodiment
With reference to the accompanying drawings and examples embodiments of the present invention are done with specific description：
Two screwed pipes 1 carry out pipe screw thread connection by nipple 2, take the mode of surface mount that will be used as afterwards and drive
The piezoceramic transducer 3 of dynamic device is fixed on the surface of nipple 2, is fixed as the piezoceramic transducer 4 of receiver
In the surface of one of pipe screw thread 1, epoxy resin is uniformly smeared on two piezoceramic transducers 3,4 surfaces, carries out waterproof
Insulation processing；
Two piezoceramic transducers 3,4 are connected to NI data acquisition cards 6, NI signal acquisitions by BNC cables 5 respectively
Card 6 is connected by USB cable 7 with computer for analysis terminal 8；
Computer for analysis terminal 8 is encouraged by the sine sweep that USB cable 7 controls NI data acquisition cards 6 to generate certain frequency range
Electric signal, and pass through the output of 6 output terminal of NI data acquisition cards, it is transferred to through BNC cables 5 on piezoceramic transducer 3, excitation electricity
Signal driving piezoceramic transducer 3 generates mechanical oscillation, and piezoelectric stress ripple is formed in pipe screw thread connection, and along duct orientation
It propagates；Then, piezoceramic transducer 4 receive connected by pipe screw thread transfer come piezoelectric stress ripple signal, and converted
For electric signal, 6 input terminal of NI data acquisition cards is transferred to through BNC cables 5, NI data acquisition cards 6 are defeated by piezoceramic transducer 4
The electric signal gone out is converted into digital signal, is transferred to computer for analysis terminal 8 by USB cable 7 afterwards；
Under the normal seal operation state of the pipe screw thread defined in computer analysis system, the measured piezoelectricity as receiver
Ceramic sensor element 4 receives signal as reference signal, identification feature parameter reference value is built, afterwards by monitoring different times pipe
The identification feature parameter of measuring signal is threadedly coupled, by identification feature parameter and the comparative analysis of identification feature parameter reference value and is counted
It calculates and loosens judging quota, the sealing situation of pipe screw joint is drawn by the variation for monitoring judging quota.Defined loosening is commented
Sentence that index is bigger, then show that the more normal sealing state deviation of working condition that measured tube is threadedly coupled is bigger.
For example, the energy value for setting the reception signal of piezoceramic transducer 4 can be expressed as E
Wherein, tsAnd tfTable is divided to represent to receive the initial time of signal and finish time, y (t) and fsIt represents to receive letter respectively
Number dis-crete sample values and sample frequency.
In this case, the loosening judging quota of pipe screw thread is to receive the relative change rate R of signal energy value, by following formula
It calculates：
Wherein, EtRepresent the signal energy value of structure actual measurement, E0Represent the signal energy value under structural health sealing state,
As a reference value.Signal energy value E in above formula (2) can also be by wavelet-packet energy value, structure partial resonant frequency come generation
It replaces.
The small echo packet node coefficient r of signal is received for piezoelectric transducer, loosening judging quota can also be by small nodal point
The variation relative mean square deviation (root mean square deviation, RMSD) of coefficient r is calculated：
Wherein, riRepresent i-th of small echo packet node coefficient of structure measured signal, ri 0It represents under structural health sealing state
I-th of small echo packet node coefficient of test signal, N represent the number of small echo packet node coefficient.Wavelet packet section in its formula (3)
Dot factor r can also be replaced with signal fitting regression coefficient, factorial analysis coefficient.
The basic principle of the present invention is that two screwed pipes 1 carry out pipe screw thread connection by nipple 2, when pipe screw thread is sent out
During raw loosening leakage, the thread contact area of screwed pipe 1 and nipple 2 can change correspondingly, and loosen more serious, thread contact
Area changes the piezoelectric stress wave excitation letter bigger, the piezoceramic transducer 3 as driver generates compared to sealing state
Number by pipe screw thread connection transfer attenuation or variation it is bigger, at the same time, the piezoceramic transducer 4 as receiver receives
Stress wave signal variation it is bigger, by monitor piezoceramic transducer 4 receive piezoelectric stress ripple signal intensity can supervise
Test tube screw thread connects loosening situation, in addition, the loosening of pipe screw thread is also frequently accompanied by screwed pipe 1 and opposite turn round occurs for nipple 2
Turn.Therefore, connect by monitoring and recognizing the relative position and screw thread of screwed pipe 1 and nipple 2 caused by pipe screw thread loosens
The change of contacting surface product, you can identify the generation that pipe screw thread loosens, while to a certain extent, assess the serious journey loosened
Degree.
Here brief theory deduction is provided, as the above analysis, the loosening of pipe screw thread can cause screwed pipe 1 and screw thread
The thread contact area and relative position of connector 2 change, therefore provide brief theory respectively from these two aspects here and push away
It leads.
(1) pipe screw thread contact area changes caused by loosening
As shown in figure 3, when pipe screw thread loosens, it is assumed that 2 holding position of nipple is fixed, and screwed pipe 1 is along pine
Twist dynamic direction (it is assumed here that counterclockwise) (such as Fig. 1), at this time the thread contact face of screwed pipe 1 and nipple 2
Product reduces therewith.For pipe screw thread, it is assumed that screwed pipe 1 counterclockwise often rotates one week, the contact area with nipple 2
Reduce Δ S0, this value is i.e. definite when pipe screw thread is dispatched from the factory, and related only with the geometric parameter of pipe screw thread (diameter of thread, angle of thread are led
Journey etc.).
It is assumed here that when pipe screw thread loosens, the torsion of θ counterclockwise occurs for screwed pipe 1, and the present invention only considers to loosen to occur just
The monitoring of phase, therefore the scope of torsion angle is 0 ＜ θ≤π.Then under such loosening state, pipe screw thread contact area knots modification Δ S can
To be expressed as：
This formula can be expressed as：
Δ S ∝ θ (0 ＜ θ≤π) formula (5)
I.e. when pipe screw thread loosens, thread contact area change amount and the screwed pipe 1 of screwed pipe 1 and nipple 2
It is directly proportional along the corner for loosening direction twisting.
(2) pipe screw thread relative position changes caused by loosening
According to the specific implementation method of the present invention of above-mentioned introduction, make pottery in 1 surface mount of screwed pipe as the piezoelectricity of receiver
Porcelain sensor 4, in piezoceramic transducer 3 of 2 surface mount of nipple as driver.Under pipe thread seal state,
Two sensors 3 and 4 are on the same line along 1 length direction of screwed pipe, as shown in figure 4, and its initial relative distance
For L0.When pipe screw thread loosens, i.e., screwed pipe 1 rotates θ in the counterclockwise direction, and 3 position of piezoceramic transducer is protected at this time
Hold constant, and piezoceramic transducer 4 is rotated as θ angles occur together for screwed pipe 1, and final position is as shown in Figure 4.
Assuming that screwed pipe 1 often rotates one week in the counterclockwise direction, it is Δ that threadingly 1 length direction of pipe, which outwards back-outs length,
l0, this value is i.e. definite when pipe screw thread is dispatched from the factory, related (diameter of thread, angle of thread, helical pitch equally only with the geometric parameter of pipe screw thread
Deng).Then when screwed pipe 1 rotates counterclockwise θ, screwed pipe 1 outwards back-outs length for Δ l along its length, can be expressed as：
At the same time, with the rotation of screwed pipe 1, piezoceramic transducer 4 equally occurs along 1 circumferential direction of screwed pipe
Position change.Assuming that the radius of screwed pipe 1 is R, then when it rotates counterclockwise θ, threadingly pipe 1 of piezoceramic transducer 4
The position knots modification of circumferential direction is θ R.As shown in figure 4, two 3,4 phases under loosening state of piezoceramic transducer at this time
The L that adjusts the distance can be expressed as：
Therefore, when pipe screw thread loosens, the relative position knots modification Δ L of two piezoceramic transducers 3,4 can be with
It is expressed as：
Above-mentioned formula (8) can also be expressed as：
Δ L ∝ θ (0 ＜ θ≤π) formula (9)
I.e. when pipe screw thread loosens, it is pasted onto the piezoceramic transducer 3 on 2 surface of nipple and is pasted onto screw thread
The relative position knots modification of the piezoceramic transducer 4 on 1 surface of pipe is positively correlated with screwed pipe 1 along the corner for loosening direction twisting
Relation.
In conclusion when pipe screw thread loosens, the thread contact area of screwed pipe 1 and nipple 2 reduces therewith,
The relative position of two piezoceramic transducers 3,4 can also increase therewith simultaneously.And the piezoelectricity generated by piezoceramic transducer
The propagation law of stress wave signal in the structure understands, receives the energy attenuation degree of signal and interstructural contact area into anti-
Than contact area is bigger, and stress wave is decayed smaller after being propagated by contact surface, that is, the energy received is bigger, conversely, contact surface
Product reduces, then the energy received also decreases.Meanwhile signal receives the relative distance of position and signal source also direct relation
To the energy attenuation degree for receiving signal, receiver is nearer from signal source, then the energy received is bigger, on the contrary then smaller.Cause
This, by the attenuation degree for monitoring piezoelectric stress ripple signal energy transmission in pipe screw thread connection, you can indirectly reflect spiral shell
Line pipe 1 and the thread contact area of nipple 2 and the situation of change of relative position.When unchanged, then show that pipe screw thread is close
Envelope is good, and non-loosening leakage occurs, and otherwise then shows that loosening occurs in pipe screw thread, sealing state is connected so as to fulfill to pipe screw thread
Monitoring and examination.Method And Principle proposed by the present invention is simple, operation is easy, and loosening variation small to pipe screw thread can also accomplish standard
Really monitoring in real time and identification.
When the present invention is connected to loosening generation using pipe screw thread, relative position and screw thread between screwed pipe and nipple
Contact area changes, meanwhile, piezoelectric stress ripple signal is declined during structure-borne by the energy after actual contact surface
Subtract degree to be inversely proportional with contact area, the relation directly proportional to the relative distance of receiver and signal source, actually connect by comparing
Receive the energy of signal and the relative size of reference value under pipe thread seal state, you can simply and efficiently realize pipe thread seal
The monitoring and identification of state for improving the security of pipe screw thread connection, reduce security risk and operation risk, improve overall warp
Ji benefit, will generate positive meaning.
Claims (8)
1. a kind of monitoring method loosened for pipe screw joint, which is characterized in that this method comprises the following steps：
Step 1 by two piezoceramic transducers respectively in a manner of surface mount, is fixed on nipple and screwed pipe
Surface carries out waterproof insulation process on piezoceramic transducer surface；
Two piezoceramic transducers are connected to data collecting card, then by data collecting card by step 2 by cable respectively
It is connected with computer for analysis terminal；
Step 3, computer for analysis terminal controls data collecting card to generate the excitation electric signal of certain frequency range by cable, and passes through
Data collecting card output terminal exports, and the piezoceramic transducer as driver, excitation electric signal driving pressure are transferred to through cable
Electroceramics sensor generates mechanical oscillation, forms piezoelectric stress ripple in pipe screw thread connection, and is propagated along duct orientation；Another
Piezoceramic transducer receives the piezoelectric stress ripple signal transferred by pipe screw thread connection and is translated into electricity as receiver
Signal, the input terminal of data collecting card is transferred to through cable, and data collecting card will be defeated as the piezoceramic transducer of receiver
The electric signal gone out is converted into digital signal, and is transferred to computer for analysis terminal；
Step 4, it is measured as receiver under the normal seal operation state of the pipe screw thread defined in computer analysis system
Piezoceramic transducer signal builds identification feature parameter reference value, afterwards by monitoring follow-up military service shape as reference signal
The identification feature parameter of different times pipe screw thread connection measuring signal under state, by identification feature parameter and identification feature parameter benchmark
Value comparative analysis and the loosening judging quota for calculating pipe screw joint draw pipe screw joint by the variation for monitoring judging quota
Sealing situation.
2. a kind of monitoring method loosened for pipe screw joint according to claim 1, it is characterised in that：Step 4
In, under the normal seal operation state of pipe screw thread as receiver piezoceramic transducer reference signal, pipe screw thread is taken to install
Complete come into operation initial stage acquisition signal or by prior art detection method confirm pipe screw thread do not loosening leakage
During generation, the signal of experiment acquisition is carried out.
3. a kind of monitoring method loosened for pipe screw joint according to claim 1 or 2, it is characterised in that：In step
In rapid four, identification feature parameter is the direct measured value that can characterize signal characteristic or derivative value.
4. a kind of monitoring method loosened for pipe screw joint according to claim 3, it is characterised in that：The identification
Characteristic parameter includes receiving the energy magnitude of signal, wavelet-packet energy value, structure partial resonant frequency, signal fitting and returning
A kind of or arbitrarily several combinations in number, factorial analysis coefficient and small echo packet node coefficient.
5. a kind of monitoring method loosened for pipe screw joint according to claim 4, it is characterised in that：It loosens and judges
Index includes the relative changing value of the signal characteristic value of above-mentioned identification feature parameter and/or variation relative mean square deviation, defined pine
Dynamic judging quota is bigger, then shows that the more normal sealing state difference of service state of tested pipe screw joint is more apparent, that is, occur
It is bigger to loosen the possibility of leakage, it is more serious to loosen disease.
6. a kind of monitoring method loosened for pipe screw joint according to claim 1, it is characterised in that：Step 1
In, epoxy resin is uniformly smeared on piezoceramic transducer surface, carries out waterproof insulation process.
7. a kind of monitoring method loosened for pipe screw joint according to claim 1, it is characterised in that：The data
Capture card is NI data acquisition cards, and NI data acquisition cards are connected by BNC cables with two piezoceramic transducers respectively, NI letters
Number capture card is connected by USB cable with computer for analysis terminal.
8. a kind of monitoring method loosened for pipe screw joint according to claim 1, it is characterised in that：The computer
Analysing terminal encourages electric signal by the excitation electric signal that data collecting card generates for sine sweep.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810108140.9A CN108120574B (en) | 2018-02-02 | 2018-02-02 | Method for monitoring looseness of pipe threaded joint |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810108140.9A CN108120574B (en) | 2018-02-02 | 2018-02-02 | Method for monitoring looseness of pipe threaded joint |
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| CN108120574B CN108120574B (en) | 2022-05-13 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112923969A (en) * | 2019-12-05 | 2021-06-08 | 纳诺凯姆株式会社 | Chimney separation detection device |
| CN114545297A (en) * | 2022-02-25 | 2022-05-27 | 山东浪潮科学研究院有限公司 | Quantum measurement and control equipment connection monitoring device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106909733A (en) * | 2017-02-23 | 2017-06-30 | 长沙理工大学 | A kind of steel truss bridge key member high-strength bolt health status monitoring method |
-
2018
- 2018-02-02 CN CN201810108140.9A patent/CN108120574B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106909733A (en) * | 2017-02-23 | 2017-06-30 | 长沙理工大学 | A kind of steel truss bridge key member high-strength bolt health status monitoring method |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112923969A (en) * | 2019-12-05 | 2021-06-08 | 纳诺凯姆株式会社 | Chimney separation detection device |
| CN112923969B (en) * | 2019-12-05 | 2023-08-29 | 纳诺凯姆株式会社 | Chimney separation detection device |
| CN114545297A (en) * | 2022-02-25 | 2022-05-27 | 山东浪潮科学研究院有限公司 | Quantum measurement and control equipment connection monitoring device |
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| CN108120574B (en) | 2022-05-13 |
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