CN104792508A - Online compression amount measurement method for seal ring of small solid rocket - Google Patents

Abstract

An online compression amount measurement method for a seal ring of a small solid rocket includes: analyzing stress conditions of the seal ring; obtaining a relationship between a compression amount of the seal ring and a tightening torque by establishing a relationship between the compression amount of the seal ring and an axial stress and a relationship between the axial stress and tightening torque; further providing a technical test method for identifying a tightening torque coefficient according to a direct proportion relationship between the compression amount and the tightening torque; during technical test, writing reference values such as a reference value of the compression amount of the seal ring, a reference value of the tightening torque and the like besides the tightening torque coefficient into a database to provide a basis for judgment in online measurement; in a practical tightening process, calculating the compression amount of the seal ring by measurement of an angle and an output torque of a torque tightening motor, and writing data including a measured value of the compression amount of the seal ring, a measured value of the tightening torque and the like into the database for inquiring. By the online compression amount measurement method, real-time precision compression amount measurement of the seal ring of the small solid rocket can be realized.

Description

A kind of On-line Measuring Method of solid mouse O-ring seal decrement

Technical field

The invention belongs to Fire load assembling field, relate to a kind of measuring method of Fire load O-ring seal decrement.

Background technology

Solid mouse is a kind of typical Space Pyrotechnics Devices, and in separation, just (instead) pushes away, radome fairing separation, the satellite and the rocket rise and revolve, cover thruster, to play an important role in bullet pose adjustment and control etc.

In ground experiment in the past, the high temperature and high pressure gas once occurred because of solid mouse reveals the quality accident causing rocket to disintegrate, fault analysis finds out it is because O-ring seal compression (Normal squeezing amount is 10% ~ 30% of its thickness) not in place afterwards, fails to make positiver sealing between housing and jet pipe.According to Quality Control of Spaceflight Production requirement, must survey and record this key parameter of O-ring seal decrement, therefore need actual measurement O-ring seal decrement and charge to quality archives.As shown in Figure 1, because O-ring seal 35 can not directly be measured in thread head groove between housing 31 and jet pipe 32, therefore the current process of pre-assembled (not filling O-ring seal)-make marks-assemble (dress O-ring seal)-measurement that can only adopt in manual setting process carrys out the decrement of indirect inspection O-ring seal, the method needs twice assembling, repetitive measurement, labour intensity is large, efficiency is low, cannot adapt to the requirement of producing in enormous quantities.

From existing domestic and foreign literature, solve solid mouse O-ring seal decrement method that is automatic or on-line measurement and have no report.

Summary of the invention

The technical matters that the present invention solves is: need twice assembling, repetitive measurement, inefficient problem for current solid mouse O-ring seal decrement, propose a kind of On-line Measuring Method of solid mouse O-ring seal decrement, can not only improve the testing efficiency of O-ring seal decrement, and measurement relative error can meet requirement of engineering precision.

Technical solution of the present invention is: a kind of On-line Measuring Method of solid mouse O-ring seal decrement, comprises the steps:

(1) paper tape equal for the housing girth with rocket is divided into 360 parts, and is affixed on the oral area of housing, the paper tape only having straight line to mark is affixed on the oral area of jet pipe simultaneously; Described jet pipe and housing are directly threaded connection, and standard seal circle are placed in the sealing that jet pipe and housing are directly used in connection of thread;

(2) housing is fixed, moment of torsion is applied to jet pipe, linear mark when minimal torque being loaded divides the position of paper tape to be designated as initial 0 angle relative to part grade of 360 on housing, record the process of one group of reference torque M when being loaded on that jet pipe is relative with housing to be fixed from minimal torque, corresponding relation between the angle that linear mark turns over from initial 0 angle and the moment of torsion of applying, by the decrement that the angle conversion turned over is standard seal circle, and obtain Proportional coefficient K between the moment of torsion of applying and the decrement of standard seal circle as screw-down torque coefficient by the mode of data fitting,

(3) also recording process parameter vector [M is obtained, θ, M0, K, C1, C2], wherein θ is the decrement of standard seal circle angle value corresponding when being 20% of standard seal circle thickness, M0 is idle running moment of torsion, represents that jet pipe starts the minimal torque of rotating relative to housing, C1 gets the constant between 0.1 ~ 0.5, and C2 gets the constant between 1.1 ~ 2.0;

(4) replace standard seal circle with O-ring seal to be measured, linear mark is placed in initial 0 degree of position, then moment of torsion is applied to jet pipe, judge whether real-time screw-down torque M1 is greater than idle running moment of torsion M0, if then calculate (M1-M0)/(θ ₁-θ ₀) whether be greater than C ₁* K, θ ₀initial value be 0, θ ₁for the angle that the linear mark corresponding with M1 turns over from initial 0 angle, if (M1-M0)/(θ ₁-θ ₀) be greater than C ₁* K, then use angle θ ₁upgrade initial angle θ ₀; If (M1-M0)/(θ ₁-θ ₀) be not more than C ₁* K, then increase M1, until (M1-M0)/(θ ₁-θ ₀) be greater than C ₁* initial angle θ is upgraded after till K ₀;

(5) continue to increase real-time screw-down torque M1 and record the real-time angular θ corresponding with M1 ₁, calculate (M1-M0)/(θ ₁-θ ₀) whether be greater than C ₂* K, if be greater than, terminates the loading of real-time screw-down torque M1 immediately, and discriminating test failure is also exited; If be not more than, continue to increase real-time screw-down torque M1 until M1 is positioned at the interval of (0.9 ~ 1.1) times M;

(6) θ that record is corresponding with M1 now ₁, then calculate Δ L ₁=(θ ₁-θ ₀)/360*R, wherein R for described in the pitch that is threaded, if Δ L ₁be positioned at the interval range of (10%-30%) Δ L, then discriminating test is qualified, by Δ L ₁as the decrement of O-ring seal to be measured, otherwise discriminating test failure and exit, wherein Δ L=θ/360*R.

The present invention's advantage is compared with prior art: the present invention draws screw-down torque and the proportional relation of O-ring seal decrement, i.e. screw-down torque coefficient by theoretical analysis, and screw-down torque coefficient can be determined by engineer testing; Obtain in test on the basis of screw-down torque coefficient, utilize screw-down torque and the angle value of actual measurement, automatically calculate O-ring seal decrement.The present invention is except needing to do engineer testing with except obtaining screw-down torque coefficient and needing twice assembling when renewing specification O-ring seal, all the other assemblings all can once complete, and automatically can record screw-down torque value, O-ring seal circle compression value.The invention solves prior art and need twice assembling, the problem of repetitive measurement multiple size indirect calculation O-ring seal decrement, less assembling number of times and Measuring Time, improve the testing efficiency of O-ring seal decrement.By in the test of certain solid mouse and result thereof, the inventive method not only increases measurement efficiency, and measures relative error within 5%, reaches the object of on-line measurement.

Accompanying drawing explanation

Fig. 1 is the position view of O-ring seal at solid mouse;

Fig. 2 is the stressed schematic diagram of O-ring seal;

Fig. 3 is screw-down torque parameter identification testpieces schematic diagram of the present invention;

Fig. 4 is engineer testing data and the matched curve of screw-down torque coefficient of the present invention;

Fig. 5 is the process flow diagram of the inventive method;

Fig. 6 is the curve of the screw-down torque that obtains of the present invention and O-ring seal decrement.

Embodiment

First the present invention analyzes the stressing conditions of O-ring seal, and by setting up the relation of O-ring seal decrement and axially loaded, the relation of axial force and screw-down torque has drawn the relation of O-ring seal decrement and screw-down torque further; Be direct proportionality (by this scale-up factor called after screw-down torque COEFFICIENT K) by decrement and screw-down torque, further provide the method identification screw-down torque coefficient by engineer testing; In engineer testing, except screw-down torque COEFFICIENT K, also by O-ring seal decrement reference value M, screw-down torque reference value θ etc., by these reference value write into Databasces, the judgement for on-line measurement provides foundation; In actual rundown process, tightening angle and the output torque of motor by measuring moment of torsion, O-ring seal contracting amount can be calculated, and by O-ring seal decrement measured value, in the data write into Databasces such as screw-down torque measured value, for inquiry.

One, the computation model of O-ring seal screw-down torque coefficient is set up

(1) relation of O-ring seal decrement and pretightning force

Axially there is deformation owing to being subject to axial pre tightening force F in O-ring seal, as shown in Figure 2, known by Analysis of materials mechanics:

$F=\frac{\mathrm{\ΔL}}{L}\mathrm{EA}---\left(1\right)$

Wherein, E-elastic modulus, only depends on draw materials this body structure and temperature, and other conditions have nothing to do; A-O-ring seal cross-sectional area; L-O-ring seal thickness; Δ L-O-ring seal decrement.

If O-ring seal be look at a spring, then the O-ring seal of often kind of specification just corresponding a kind of spring, can define its elasticity coefficient K ₁, from Hooke's law,

$K_1=\frac{F}{\mathrm{\ΔL}}=\frac{\mathrm{EA}}{L}---\left(2\right)$

The pass that can obtain axial pre tightening force and O-ring seal decrement is further,

F＝K ₁·ΔL (3)

(2) screw-down torque of screw thread and the relation of axial force

The mechanical analysis of screw thread pair, generally first launches to be considered as inclined-plane according to square thread stressed, then turns to triangle thread by projection relation, can draw the relation of screw-down torque and axial pre tightening force.Consult the mechanical design handbook (2012) that Wen Bangchun etc. writes known, the pass of screwed tight moment and axial force is:

M＝K ₂·F·d (4)

Wherein, M-screw-down torque; K2-scale-up factor (relevant with factors such as screw thread pair material, lubricating status); ; D-pitch diameter of thread.

(3) relation of screw-down torque and O-ring seal decrement.

Formula (3) is substituted into formula (4), the relation of screw-down torque and O-ring seal decrement can be obtained

M＝KΔL (5)

Wherein, screw-down torque COEFFICIENT K=K ₁k ₂d.As can be seen from formula (5), the decrement of screw-down torque and O-ring seal is proportional, and this provides theoretical foundation to measurement O-ring seal decrement automatically.

Screw-down torque COEFFICIENT K can be calculated, but affects by factors such as screw thread process, thread-shaped face, frictions, and the error of calculation is comparatively large, generally carrys out identification by engineer testing and determines.

Two, the acquisition of O-ring seal screw-down torque COEFFICIENT K

Generally screw-down torque coefficient is obtained by engineer testing when engineer applied.

Below for certain model solid mouse, introduce concrete steps as follows:

(1) scale paper tape 34 is made.The paper tape equal with storepipe 31 girth is divided into 360 parts, and is affixed on housing 31 oral area.And the paper tape 33 printing straight line mark is affixed on jet pipe 32 oral area, as shown in Figure 3.

(2) moment of torsion load test.Solid mouse is fixed on vice 30, uses dial torque wrench 36 to apply moment of torsion.Load test mainly comprises: 1) adopt discrete method to load moment of torsion (2Nm mono-grade within 10Nm; The every 10Nm of 10 ~ 100Nm mono-grade; The every 20Nm of 100 ~ 200Nm mono-grade; More than 200Nm 50Nm mono-grade); 2) often load one grade of moment of torsion, read corresponding angles angle value (being now absolute angle), be loaded into reference to till moment (empirical value being obtained by technical papers or test) always; 3) O-ring seal is changed, revision test three times.Wherein, apply when being greater than the minimal torque of idle running moment of torsion M0, the straight line of paper tape 33 is defined as initial angle (being designated as 0 angle) for the angle of paper tape 34, and initial angle is the foundation judging whether O-ring seal compresses; Other absolute angle all deducts initial angle, is converted into relative angle angle value.

(3) torque coefficient obtains.

Table 1 is the angle-screw-down torque test figure of certain mouse.First to three times test angle-data and torque data be averaging processing, then use least square fitting calculate screw-down torque COEFFICIENT K.

Relative angle θ after converting is converted into O-ring seal decrement Δ L, and physical relationship is Δ L=θ/360*R, and wherein R is thread pitch, and the pitch as this experiment solid mouse is 1.5mm, then R=1.5.

Fig. 4 is test figure, and the screw-down torque COEFFICIENT K that can obtain this kind of O-ring seal by least square method is 1469.5.

Table 1 screw-down torque parameter identification technological experiment data

Three, the determination of other parameters of O-ring seal decrement on-line measurement

Each model solid mouse assembly technology parameter vector [M, θ, M0, K, C1, C2] is determined, by all technological parameters vector composition assembly parameter database by engineer testing in early stage.Wherein, M-screw-down torque reference value (technical papers obtains or test is determined), θ-O-ring seal decrement reference value (angle of O-ring seal thickness 20% correspondence), M0-idle running moment of torsion reference value (friction square of screw thread pair when O-ring seal is uncompressed, this value is relevant with factors such as screw thread process state and friction lubricating status, be generally below 10N.m, can be obtained by test), K-screw-down torque coefficient, C1 with C2 be characterize decrement different time O-ring seal self compression performance difference.C1 generally gets the constant between 0.1 ~ 0.5, and C2 generally gets the constant between 1.1 ~ 2.0.

The reference value θ of O-ring seal decrement corresponding angle, moment of torsion reference value M are all arranging certain domain of walker, and angle θ domain of walker is generally taken as 50%-150%, and the domain of walker of moment of torsion M is generally taken as 90%-110%.

For aforementioned same rocket O-ring seal, obtaining technological parameter vector by technical papers and test is [450,48,2,1469.5,0.5,2].Wherein M=450 represents that reference torque is 450N.m, obtains from technical papers; θ=72, O-ring seal thickness is 1mm, and its decrement should be 1*20%=0.2mm, and corresponding angle is 0.2/1.5*360 °=48 °, pitch 1.5mm.M0=2N.m represents idle running moment of torsion, and test is determined; Screw-down torque COEFFICIENT K=1469.5 are determined by test; C1=0.5, C2=2 are chosen by test and determine.

Four, the enforcement of O-ring seal decrement on-line measurement

The ultimate principle that O-ring seal decrement is measured is by the real-time detection to angle and screw-down torque, and more real-time torque coefficient is (with (M1-M0)/(θ ₁-θ ₀) calculate) and torque coefficient K, judge that the start angle that O-ring seal compresses and final angle realize the indirect inspection to sealing gasket decrement.Judgment rule is, C1*K≤(M1-M0)/(θ ₁-θ ₀during)≤C2*K, O-ring seal is in normal compressive state; (M1-M0)/(θ ₁-θ ₀during)≤C1*K, O-ring seal is not compressed; (M1-M0)/(θ ₁-θ ₀during)>=C2*K, the exception of O-ring seal own or screw thread stuck.Torque loading system (torque loading system selects conventional tightening machine) detects the corner (being converted into O-ring seal decrement) of torque axis in real time while control torque, until screw-down torque meets certain limit (be generally reference torque ± 10%), decrement meets 10% ~ 30% of its thickness and just completes moment of torsion and load.In moment of torsion loading procedure, not only will judge torque value, whether angle value meets certain standard, also will judge whether moment of torsion loading procedure is in normal condition etc., calculates O-ring seal decrement etc.As shown in Figure 5, moment of torsion load and O-ring seal decrement detect key step as follows:

(1) from the assembly technology database in earlier stage obtained, technological parameter vector [M, θ, M0, K, C1, C2] is called in.

(2) load moment of torsion, judge whether real-time screw-down torque M1 is greater than idle running moment of torsion M0, judge actual measurement angle θ if then preliminary ₁may be the initial angle θ of O-ring seal compression ₀(θ ₀initial value be set to 0).Calculate real-time torque coefficient (M1-M0)/(θ ₁-θ ₀) whether be greater than C ₁* K, if set up, determines this moment corresponding θ ₁for initial angle, for upgrading θ ₀, and in this, as the Calculation Basis of O-ring seal decrement; Otherwise increase moment of torsion and upgrade angle until (M1-M0)/(θ that satisfies condition ₁-θ ₀) be greater than C ₁*, till K, initial angle θ is found ₀.If until M1 arrives 0.9 times of M do not find initial angle θ yet ₀, then unsuccessfully exit.

(3) continue to increase screw-down torque, calculate (M1-M0)/(θ ₁-θ ₀), judge whether to be greater than C2*K, to there are the abnormal conditions such as screw thread is stuck between screw thread pair if set up, terminating screw-down torque immediately loads, and unsuccessfully exits; Otherwise continue to load until screw-down torque M1 is 0.9-1.1 times of reference torque M, decrement angle θ ₁-θ ₀for the 0.5-2 with reference to angle θ doubly till.

(4) under the condition that moment of torsion is qualified, judge that whether qualified (meet O-ring seal decrement after angle conversion is 10%-30% to angle, if satisfy condition, this tightens qualified end, and angle value is converted into decrement, moment of torsion measured value write into Databasce; If be less than 10%, show that compression is not in place, assemble and unsuccessfully terminate.

For certain solid mouse (parameter is as table 2) aforementioned, the relation curve of screw-down torque and O-ring seal decrement can be obtained in this way as shown in Figure 6, and screw-down torque can be obtained and O-ring seal decrement is 452Nm, 0.225mm respectively.Achieve the automatic measurement of O-ring seal decrement.Simultaneously in same single test, it is 0.220mm that the method (simulation manual measurement) made marks before utilizing measures the O-ring seal decrement drawn.Can find out that relative relative error is 2.2%, visible this method is effective.

Certain solid mouse parameter list of table 2

The content be not described in detail in instructions of the present invention belongs to the known technology of those skilled in the art.

Claims (1)

1. an On-line Measuring Method for solid mouse O-ring seal decrement, is characterized in that comprising the steps:

(1) paper tape equal for housing (31) girth with rocket is divided into 360 parts, and is affixed on the oral area of housing (31), the paper tape only having straight line to mark is affixed on the oral area of jet pipe (32) simultaneously; Described jet pipe (32) and housing (31) are directly threaded connection, and standard seal circle are placed in the sealing that jet pipe (32) and housing (31) are directly used in connection of thread;

(2) housing (31) is fixed, moment of torsion is applied to jet pipe (32), linear mark when minimal torque being loaded divides the position of paper tape to be designated as initial 0 angle relative to 360 parts of grades on housing (31), record the process of one group of reference torque M when being loaded on that jet pipe (32) is relative with housing (31) to be fixed from minimal torque, corresponding relation between the angle that linear mark turns over from initial 0 angle and the moment of torsion of applying, by the decrement that the angle conversion turned over is standard seal circle, and obtain Proportional coefficient K between the moment of torsion of applying and the decrement of standard seal circle as screw-down torque coefficient by the mode of data fitting,

(3) also recording process parameter vector [M is obtained, θ, M0, K, C1, C2], wherein θ is the decrement of standard seal circle angle value corresponding when being 20% of standard seal circle thickness, M0 is idle running moment of torsion, represents that jet pipe (32) starts the minimal torque of rotating relative to housing (31), C1 gets the constant between 0.1 ~ 0.5, and C2 gets the constant between 1.1 ~ 2.0;

(4) standard seal circle is replaced with O-ring seal to be measured, linear mark is placed in initial 0 degree of position, then moment of torsion is applied to jet pipe (32), judge whether real-time screw-down torque M1 is greater than idle running moment of torsion M0, if then calculate (M1-M0)/(θ ₁-θ ₀) whether be greater than C ₁* K, θ ₀initial value be 0, θ ₁for the angle that the linear mark corresponding with M1 turns over from initial 0 angle, if (M1-M0)/(θ ₁-θ ₀) be greater than C ₁* K, then use angle θ ₁upgrade initial angle θ ₀; If (M1-M0)/(θ ₁-θ ₀) be not more than C ₁* K, then increase M1, until (M1-M0)/(θ ₁-θ ₀) be greater than C ₁* initial angle θ is upgraded after till K ₀;

(5) continue to increase real-time screw-down torque M1 and record the real-time angular θ corresponding with M1 ₁, calculate (M1-M0)/(θ ₁-θ ₀) whether be greater than C ₂* K, if be greater than, terminates the loading of real-time screw-down torque M1 immediately, and discriminating test failure is also exited; If be not more than, continue to increase real-time screw-down torque M1 until M1 is positioned at the interval of (0.9 ~ 1.1) times M;

(6) θ that record is corresponding with M1 now ₁, then calculate Δ L ₁=(θ ₁-θ ₀)/360*R, wherein R for described in the pitch that is threaded, if Δ L ₁be positioned at the interval range of (10%-30%) Δ L, then discriminating test is qualified, by Δ L ₁as the decrement of O-ring seal to be measured, otherwise discriminating test failure and exit, wherein Δ L=θ/360*R.