CN104044069B - Based on acoustic emission signal optical work sub-surface damage depth prediction approach - Google Patents

Based on acoustic emission signal optical work sub-surface damage depth prediction approach Download PDF

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CN104044069B
CN104044069B CN201410317669.3A CN201410317669A CN104044069B CN 104044069 B CN104044069 B CN 104044069B CN 201410317669 A CN201410317669 A CN 201410317669A CN 104044069 B CN104044069 B CN 104044069B
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acoustic emission
depth
formula
grinding
emission signal
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CN104044069A (en
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姜晨
王春华
李郝林
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University of Shanghai for Science and Technology
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University of Shanghai for Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B24B49/003—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving acoustic means

Abstract

The present invention relates to a kind of based on acoustic emission signal optical work sub-surface damage depth prediction approach, steps of the method are: set up the optical work sub-surface damage degree of depth and acoustic emission signal relational model；The surface damage degree of depth and acoustic emission signal relational model constant calibration；Sub-surface damage degree of depth on-line prediction is carried out by acoustic emission signal.The present invention is with low cost, and can quickly, accurately, nondestructively predict subsurface stratum crackle expansion depth, reduce processing cost by optimization processing technology parameter and shorten the purpose of follow-up polishing time.

Description

Based on acoustic emission signal optical work sub-surface damage depth prediction approach
Technical field
The invention belongs to mechanical field, relate to a kind of based on acoustic emission signal optical work sub-surface damage depth prediction side Method.
Background technology
Sub-surface damage would generally reduce the intensity of optical element, long-time stability, image quality, coating quality and resist sharp The important performance indexes such as light injury threshold.Grinding for optical element, if it is possible to predict subsurface stratum quickly and accurately The expansion depth of crackle, it is possible to reduce processing cost by optimization processing technology parameter and shorten the follow-up polishing time Purpose.In order to predict the expansion depth of subsurface stratum crackle accurately and rapidly, there has been proposed substantial amounts of destructiveness and non-demolition Property detection method, is very easy to the processing of optical element.The essence of destructive detection method is to utilize angle polishing method, throwing The physical methods such as photo-engraving process, cross section microscopy and MRF disclose the pattern of subsurface stratum damage, by detection bosom The position that crackle occurs directly obtains the expansion depth of subsurface stratum crackle to the distance of surface of the work.Destructive detection method is not only Waste time and energy and inevitably destroy surface of the work, easily cause the inefficacy of workpiece.It addition, destructive detection method is only Can record the degree of depth of subsurface stratum damage under specific process technology parameter, efficiency comparison is low, is not of universal significance.Non-destructive is examined Survey method mainly has total internal reflection microscopy based on intensity detection, confocal scanning laser microscopy and quasi-polarized-light technique etc.. Although these methods can quickly detect the degree of depth of subsurface stratum crackle, but measurement result is not directly perceived, precision is relatively low, and tests and set Standby cost is the highest.
Acoustic emission (Acoustic emission, AE) is that in material regional area, strain energy quickly discharges and wink of producing Between high frequency elastic stress wave, it with workpiece material, the factor such as the state of grinding condition, wheel face have close relationship, be One of important detection means of material removal process process.
After the present invention is directed to grinding work piece, its sub-case depth is carried out the needs of fast prediction, has invented one sound and sent out Penetrate signal RMS and predict grinding work piece sub-surface damage depth computing method.
Summary of the invention
In order to predict the expansion depth of subsurface stratum crackle accurately and rapidly, based on impression Theory of Fracture Mechanics, the present invention carries Grinding work piece sub-surface damage depth computing method is predicted, by measuring grinding in real time for a kind of acoustic emission signal RMS The acoustic emission signal of journey, obtains the workpiece sub-surface damage degree of depth.
The technical solution used in the present invention is: a kind of based on acoustic emission signal optical work sub-surface damage depth prediction side Method, the key step of the method is provided with: set up the optical work sub-surface damage degree of depth and acoustic emission signal relational model, sub-surface Lesion depths and acoustic emission signal relational model constant calibration, to utilize acoustic emission signal to carry out the sub-surface damage degree of depth the most pre- Survey.Concrete steps include:
1. set up the optical work sub-surface damage degree of depth and acoustic emission signal relational model
(1) derivation grinding depth and the relational expression of acoustic emission signal
Acoustic emission rms signal becomes approximate ratio relation with normal grinding force:
AERMS=kaeFn (1)
Grinding force formula is:
Fn=K [c1]γ[vw/vs]2ε-1[ap]ε[de]1-ε (2)
In formula, K is than cutting force, and its size depends on workpiece material；
c1The coefficient relevant with sharpening density；
vwWork speed；
vsSpeed of grinding wheel；
apGrinding depth；
deEmery wheel equivalent diameter；
γ, ε dimensionless constant.
Formula (1) is updated in formula (2), obtains the relational expression of grinding depth and acoustic emission signal value, i.e. a p = log ∈ AE RMS k ae K [ c 1 ] γ [ v w / v s ] 2 ϵ - 1 [ d e ] 1 - ∈ - - - ( 3 ) ;
(2) derivation grinding surface roughness and acoustic emission signal relational expression
The empirical formula of grinding surface roughness may be used to lower exponential form and represents, i.e.
SR = C Ra v w x a p y f a v K 1 K 2 K 3 v s z d s q b s n - - - ( 4 )
C in formulaRaThe coefficient relevant with by mill Material Physics mechanical property；
dsGrinding wheel diameter；
bsGrinding wheel width；
faAxial feeding；
K1The coefficient relevant with grinding wheel graininess；
K2The coefficient relevant with sparking out number of times；
K3The coefficient relevant with grinding fluid；
SR grinding surface roughness.
X, y, v, z, q, n dimensionless constant
Formula (3) is substituted into formula (4) relationship expression between grinding surface roughness and acoustic emission signal can be derived Formula:
SR = C Ra v w x ( log ∈ AE RMS k de K [ c 1 ] γ [ v w / v s ] 2 ϵ - 1 [ d e ] 1 - ∈ ) y f a v K 1 K 2 K 3 v s z d s q b s n - - - ( 5 )
(3) relational model between the derivation workpiece surface damage degree of depth and acoustic emission signal
Relational theory model between the grinding sub-surface damage degree of depth and surface roughness is:
In formula,
ak=0.027+0.090 (m-1/3),
Wherein, SSD is the sub-surface damage degree of depth, k0For the correction factor of elastic deformation centering position crack depth, φ is pressure Head tooth angle, E is elasticity modulus of materials, and H is material hardness, KcFor material fracture toughness, m is a dimensionless constant, and value is situated between Between 1/3 and 1/2.
After formula (5) is substituted into formula (6), then can obtain the relation mould between the sub-surface damage degree of depth and acoustic emission signal Type, i.e.
2. the sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
(1) steady statue acoustic emission signal RMS value measures
First being arranged on emery wheel by sensor, the other end of sensor connects capture card, surveys grinding optics with capture card Workpiece fabrication is launched signal RMS.Steady statue acoustic emission signal RMS value measures before starting, and acoustic emission grinding detected is former Beginning signal is converted to root-mean-square rms signal AERMS, its expression formula is:
AE RMS ( t ) = 1 ΔT ∫ 0 ΔT V 2 ( t ) dt - - - ( 8 )
V acoustic emission primary signal in above formula；
The △ T time window cycle.
The most once try processing, stablize grinding status when entering after emery wheel contact workpiece a period of time, measure stable All sampled points are averaged by acoustic emission rms signal during grinding status, and this value is as steady statue acoustic emission RMS value AERMS。
(2) the detection workpiece sub-surface damage degree of depth
With chemical method for etching detect the workpiece sub-surface damage degree of depth, react with workpiece after preparing chemical solution, by by The change of layer etching and corresponding etch-rate obtains etch step, then utilizes atomic force microscope, surface profiler etc. to observe The pattern of sub-surface damage layer under different depth, and then obtain depth S SD of sub-surface damage.
(3) the sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
By in formula (7)It is set to constant m, Then formula (7) is transformed to
SSD = m · ( log ∈ AE RMS k ae K [ c 1 ] γ [ v w / v s ] 2 ϵ - 1 [ d e ] 1 - ϵ ) 4 y / 3 - - - ( 9 )
There are two unknown number m and AE on formula (9) the rightRMS, then this formula could be utilized after needing to demarcate the value of formula (9) parameter m Carry out sub-surface damage depth S SD on-line prediction.Parameter m scaling method is: according to the AE obtained in step (1) and (2)RMSWith SSD value and formula (9) other parameter values, be calculated the value of m, and the value generation of m returned to the Asia after formula (9) obtains constant calibration The surface damage degree of depth and acoustic emission signal relational model.
3. utilize acoustic emission signal to carry out sub-surface damage degree of depth on-line prediction
In optical work carries out formal grinding, first gather acoustic emission signal with capture card, utilize formula (8) to incite somebody to action The acoustic emission primary signal of grinding detection is converted to root-mean-square rms signal, and measures the acoustic emission obtaining under grinding steady statue Signal RMS value AERMS.According to AERMSValue and the value of formula (9) other parameters, utilize formula (9) to be calculated workpiece Asia table Surface damage depth S SD, thus realize utilizing acoustic emission signal to carry out workpiece sub-surface damage degree of depth on-line prediction.
The present invention is with low cost, and can quickly, accurately, nondestructively predict subsurface stratum crackle expansion depth, pass through Optimization processing technology parameter reduces processing cost and shortens the purpose of follow-up polishing time.
Accompanying drawing explanation
Fig. 1 is the basic step schematic flow sheet of the present invention；
Fig. 2 is the sub-surface damage degree of depth reasoning flow schematic diagram with acoustic emission signal relational model of the present invention.
Detailed description of the invention
The present invention is further elaborated below in conjunction with the accompanying drawings.
As depicted in figs. 1 and 2, the optical work that the embodiment of the present invention is selected is K9 glass, and emery wheel is skive, uses The acoustic emission signal RMS prediction K9 glass sub-surface damage degree of depth, step includes:
1. set up the optical work sub-surface damage degree of depth and acoustic emission signal relational model
The step 1 in foregoing invention content is utilized to obtain the sub-surface damage degree of depth and acoustic emission rms signal relational model:
The 2.K9 glass sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
(1) steady statue acoustic emission signal RMS value measures
First being arranged on skive by sensor, the other end of sensor connects capture card, surveys mill with capture card Cut transmitting signal RMS in K9 glass process.Steady statue acoustic emission signal RMS value measures before starting, and utilizes formula (8) grinding to be examined The acoustic emission primary signal surveyed is converted to root-mean-square rms signal AERMS.The most once try processing, when emery wheel contacts workpiece one Enter after the section time and stablize grinding status, measure acoustic emission rms signal when stablizing grinding status, all sampled points are averaging Value, this value is as steady statue acoustic emission rms signal AERMS。
(2) the detection K9 glass sub-surface damage degree of depth
The workpiece K9 glass sub-surface damage degree of depth is detected with chemical method for etching, anti-with K9 glass after preparing chemical solution Should, by successively etching and the change of corresponding etch-rate obtains etch step, then utilize then utilize atomic force microscope, Surface profilers etc. observe the pattern of sub-surface damage layer under different depth, and then obtain K9 glass sub-surface damage depth S SD.
(3) the K9 glass sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
According to the association attributes of K9 glass, in formula (7), correlation coefficient is taken as: ε=0.87, γ=0.5, y=0.56.And will In formula (7)Be set to parameter m, then formula (7) is transformed to
SSD = m · ( log 0.87 AE RMS k ae K [ c 1 ] 0.5 [ v w / ] v s 0.74 [ d e ] 0.13 ) 0.75 - - - ( 9 )
There are two unknown number m and AE on formula (9) the rightRMS, then this formula could be utilized after needing to demarcate the value of formula (9) constant m Carry out sub-surface damage depth S SD on-line prediction.Parameter m scaling method is: according to the AE obtained in step (1) and (2)RMSWith SSD value and formula (9) other parameter values, be calculated the value of m, and the value generation of m returned to the K9 after formula (9) obtains constant calibration The glass sub-surface damage degree of depth and acoustic emission signal relational model.
3. utilize acoustic emission signal to carry out K9 glass sub-surface damage degree of depth on-line prediction
In optical work carries out formal grinding K9 glass processing, first gather acoustic emission signal with capture card, to all Averaging in collection point, this value is as steady statue acoustic emission rms signal, and utilizes formula (8) to be calculated AERMSValue.Root According to AERMSValue and the value of formula (9) other parameters, utilize formula (9) to be calculated workpiece sub-surface damage depth S SD, from And realize utilizing acoustic emission signal to carry out workpiece sub-surface damage degree of depth on-line prediction.

Claims (1)

1. one kind based on acoustic emission signal optical work sub-surface damage depth prediction approach, it is characterised in that the step of the method Suddenly it is:
(1) the optical work sub-surface damage degree of depth and acoustic emission signal relational model are set up
A. grinding depth and the relational expression of acoustic emission signal
Acoustic emission signal rms signal becomes approximate ratio relation with normal grinding force:
(1)
K in formulaaeFor the proportionality coefficient of acoustic emission signal RMS Yu grinding force, AERMSFor acoustic emission signal RMS value；
Grinding force formula is:
(2)
F in formulanGrinding force, in formulaRatio cutting force, its size depends on workpiece material；
The coefficient relevant with sharpening density；
Work speed；
Speed of grinding wheel；
Grinding depth；
Emery wheel equivalent diameter；
γ, ε dimensionless constant；
Formula (1) is updated in formula (2), obtains the relational expression of grinding depth and acoustic emission signal value, i.e.
(3)；
B. grinding surface roughness and acoustic emission signal relational expression
The empirical formula of grinding surface roughness may be used to lower exponential form and represents, i.e.
(4)
In formulaThe coefficient relevant with by mill Material Physics mechanical property；
Grinding wheel diameter；
Grinding wheel width；
Axial feeding；
The coefficient relevant with grinding wheel graininess；
The coefficient relevant with sparking out number of times；
The coefficient relevant with grinding fluid；
Grinding surface roughness；
X, y, v, z, q, n dimensionless constant
Formula (3) is substituted into formula (4) and can derive the relational expression between grinding surface roughness and acoustic emission signal:
(5)；
C. the relational model between the derivation workpiece surface damage degree of depth and acoustic emission signal
Relational theory model between the grinding sub-surface damage degree of depth and surface roughness is:
(6)
In formula,
,
Wherein, SSD is the sub-surface damage degree of depth, k0For the correction factor of elastic deformation centering position crack depth, φ is pressure head acutance Angle, E is elasticity modulus of materials, and H is material hardness, KcFor material fracture toughness, m is a dimensionless constant, and value is between 1/3 He Between 1/2；
After formula (5) is substituted into formula (6), then can obtain the relational model between the sub-surface damage degree of depth and acoustic emission signal, i.e.
(7)；
(2) the sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
A. steady statue acoustic emission signal RMS value measures
First being arranged on emery wheel by sensor, the other end of sensor connects capture card, surveys grinding optical work with capture card During acoustic emission signal, steady statue acoustic emission signalBefore pH-value determination pH starts, the acoustic emission that grinding is detected Primary signal is converted to root-mean-squareSignal, its expression formula is:
(8)
In above formulaAcoustic emission primary signal；
The time window cycle；
The most once try processing, stablize grinding status when entering after emery wheel contact workpiece a period of time, measure and stablize grinding Acoustic emission signal during state, all sampled points to be averaged, this value is as steady statue acoustic emission signalValueAE RMS；
B. the detection workpiece sub-surface damage degree of depth
Detect the workpiece sub-surface damage degree of depth with chemical method for etching, react with workpiece after preparing chemical solution, by successively losing Carve and the change of corresponding etch-rate obtains etch step, then utilize atomic force microscope, surface profiler to observe different deep The pattern of the lower sub-surface damage layer of degree, and then obtain depth S SD of sub-surface damage:
C. the sub-surface damage degree of depth and acoustic emission signal relational model constant calibration
By in formula (7)It is set to constant μ, then formula (7) it is transformed to(9)
Formula (9) the right have two unknown number μ and, then this formula could be utilized to enter after needing to demarcate the value of formula (9) parameter μ Row sub-surface damage depth S SD on-line prediction, parameter μ scaling method is: obtain according in step (1) and (2)With SSD value and formula (9) other parameter values, be calculated the value of μ, and the value generation of μ returned to the Asia after formula (9) obtains constant calibration The surface damage degree of depth and acoustic emission signal relational model；
(3) acoustic emission signal is utilized to carry out sub-surface damage degree of depth on-line prediction
In optical work carries out formal grinding, first gather acoustic emission signal with capture card, utilize formula (8) by grinding The acoustic emission primary signal of detection is converted to root-mean-squareSignal, and measure the acoustic emission letter obtaining under grinding steady statue Number RMS value AERMS；According to AERMSValue and the value of formula (9) other parameters, utilize formula (9) to be calculated surface, workpiece Asia Lesion depths SSD, thus realize utilizing acoustic emission signal to carry out workpiece sub-surface damage degree of depth on-line prediction.
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