CN109014544A - Miniature resistance spot welding quality on-line monitoring method - Google Patents

Miniature resistance spot welding quality on-line monitoring method Download PDF

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CN109014544A
CN109014544A CN201810938371.2A CN201810938371A CN109014544A CN 109014544 A CN109014544 A CN 109014544A CN 201810938371 A CN201810938371 A CN 201810938371A CN 109014544 A CN109014544 A CN 109014544A
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spot welding
miniature
resistance spot
quality
monitoring
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CN109014544B (en
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范秋月
谢煌生
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Longyan University
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Longyan University
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00Resistance welding; Severing by resistance heating
    • B23K11/24Electric supply or control circuits therefor
    • B23K11/25Monitoring devices
    • B23K11/252Monitoring devices using digital means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00Resistance welding; Severing by resistance heating
    • B23K11/10Spot welding; Stitch welding
    • B23K11/11Spot welding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K31/00Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/12Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
    • B23K31/125Weld quality monitoring

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Quality & Reliability (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
  • Resistance Welding (AREA)

Abstract

The present invention relates to a kind of miniature resistance spot welding quality on-line monitoring methods, belong to miniature resistance quality monitoring of resistance spot welding technical field.First with single-photon detector in miniature resistance spot welding production process electrode and workpiece engagement edge number of photons change with time situation carry out real-time monitoring, draw out photon change curve.The photon characteristic quantity of the miniature joint for resistance spot welding quality of different quality grade is extracted using data mining means, generate miniature resistance spot welding quality disaggregated model, the database of the miniature resistance quality monitoring of resistance spot welding based on photon signal is established, realizes miniature joint for resistance spot welding quality automatic on-line monitoring under different technology conditions.On-line monitoring for miniature resistance spot welding quality provides new way, and the single-photon detector used is high to the detectivity of nugget change of temperature field, improves the high reliablity of the online quality-monitoring of miniature resistance spot welding.

Description

Miniature resistance spot welding quality on-line monitoring method
Technical field
The present invention relates to miniature resistance quality monitoring of resistance spot welding technical field, in particular to a kind of miniature resistance spot welding quality exists Line monitoring method.By monitoring the photon variable signal in nearly nugget region in miniature resistance spot welding process, by data mining side Method extracts the nearly nugget region photon variation characteristic of different miniature joint for resistance spot welding credit ratings, generates miniature resistance spot welding matter Monitoring model online is measured, the database of the miniature joint for resistance spot welding quality-monitoring based on photon signal is established.
Background technique
Miniature resistance spot welding is widely used in fields such as medical instrument, electronic equipment, battery packages, especially current new energy The power battery of source automobile is packed, common lithium battery it is series-parallel in miniature resistance spot welding technique be used widely.
The comprehensive function of the multiple physical fields such as the thermopower as involved in spot welding production process causes tack-weld quality unstable Fixed, especially miniature resistance spot welding, weld interval generally concentrates on 2-3ms, and extremely short weld interval is to miniature resistance spot welding matter Amount on-line monitoring is put forward higher requirements.
The workpiece of miniature resistance spot welding is relatively thin, and electrode displacement, the variation of electrode force are unobvious in nugget forming process, and Electrode displacement sensor and electrode dynamic pressure transducer anti-interference ability are poor, are that electrode displacement monitoring method and electrode force monitor Method brings certain difficulty.
The temperature field in nugget region and tack-weld quality are closely related, existing infrared temperature field on-line monitoring side Method, the infrared temperature monitor response time used and photon sensitivity are poor, are difficult to capture miniature nugget formation in resistance spot welding and are formed All processes temperature information.
Summary of the invention
The purpose of the present invention is to provide a kind of miniature resistance spot welding quality on-line monitoring methods, solve present micro electric Hinder point quality on-line monitoring technique there are the problem of, miniature resistance spot welding matter is established based on nearly nugget region photon signal feature It measures monitoring model online and establishes miniature resistance quality monitoring of resistance spot welding database in conjunction with a variety of miniature resistance spot welding parameters.
Above-mentioned purpose of the invention is achieved through the following technical solutions:
Miniature resistance spot welding quality on-line monitoring method produced miniature resistance spot welding first with single-photon detector The number of photons of electrode in the journey and workpiece engagement edge situation that changes with time carries out real-time monitoring, and it is bent to draw out photon variation Line;By metallographic test determine spot welding different technology conditions under miniature joint for resistance spot welding credit rating, different quality it is miniature Photon change curve is different in resistance spot welding process, and the miniature resistance spot welding of different quality grade is extracted using data mining means The photon characteristic quantity of quality generates miniature resistance spot welding quality disaggregated model, establishes the miniature resistance spot welding based on photon signal The database of quality-monitoring realizes miniature resistance spot welding quality automatic on-line monitoring under different technology conditions;It specifically includes as follows Step:
Selection of the step (1) to the characteristic quantity of photon signal;
Step (2) analyzes the characteristic quantity of acquisition, and the threshold value for obtaining each characteristic quantity is initial judgment basis;
Step (3), the characteristic quantity according to obtained in step (1) about photon variation, establish miniature resistance spot welding quality Model, to guarantee miniature resistance quality monitoring of resistance spot welding accuracy rate, using the method for dual model cross validation to miniature resistance spot welding Quality is monitored.During miniature resistance quality monitoring of resistance spot welding model foundation, at random by the miniature resistance spot welding of initial input Sample number N points are two parts, respectively training sample set N1 and test sample set N2;
The monitoring model of step (4), the Decision boundaries that step (2) are obtained and step (3) foundation corresponds to technological parameter It is stored in miniature resistance spot welding monitoring system database.
It is to the selection of the characteristic quantity of monitoring signals described in step (1):
(1.1) welding current is started to the number of photons in welding current end time section to add up, when obtaining welding Interior total number of photons P;
(1.2) data mining is carried out with the change curve of weld interval t to number of photons c, extracts and reflects miniature resistance spot welding The photon characteristic quantity of joint quality: the number of photons c of welding current time started is respectively obtainedstart, generally with minimum number of photons one It causes, maximum photon number cmax, transfer in photon curve number m, and each time corresponding number of photons c that transferstr1、ctr2、 ctr3.。。。。。ctrm, transfer corresponding time t twicetr1、ttr2、ttr3……ttrmAnd balancing photon number institute duration tb
(1.3) in current duration t, every 0.2ms time interval calculates separately the total number of light photons c in every time1、 c2….cn-1、cnAs characteristic quantity, wherein n=t/0.2;
(1.4) according to formula of varianceCalculate the Variance feature amount σ of each miniature resistance spot welding number of photons2, Wherein c is to change number of photons with weld interval t, and μ is that welding current started into the welding current end time, all photons Average;
(1.5) test the photon signal in simultaneously monitoring process to common quality problem in miniature resistance spot welding process, The miniature joint for resistance spot welding of different quality is obtained, by metallographic test, determines the joint quality etc. of miniature resistance spot welding sample Grade is respectively labeled as excellent 2, good 3, qualified 4, unqualified 0;
(1.6) the quality classification grade in step (1.5) is only used for during miniature resistance spot welding quality model foundation Classification, quality model in actual application will excellent 2, good 3, qualified 4 categories combinations be grade 1, that is, lead to and belong to qualified spot welding Connector 1, unqualified tack-weld are 0;
(1.7) by the characteristic quantity in step (1.1), (1.2), (1.3), (1.4) and four quality in step (1.5) etc. Grade does correlation analysis, rejects the relevant characteristic quantity of partial linear, obtains and miniature joint for resistance spot welding credit rating phase relation The biggish characteristic quantity of number.
Step analyzes the characteristic quantity of acquisition described in (2), and the threshold value for obtaining each characteristic quantity is initial judgment basis, Specifically:
(2.1) probability according to each characteristic quantity of the different miniature joint for resistance spot welding credit ratings of Gaussian Profile statistics is close Degree;
(2.2) according to the different application of miniature joint for resistance spot welding, different miniature joint for resistance spot welding quality are rejected The probability density overlapping interval of each characteristic quantity of grade, between determining the suitable high density area of each characteristic quantity, as initial decision threshold Value;
Above-mentioned credit rating is: excellent 2, good 3, qualification 4, unqualified 0.
Miniature resistance quality monitoring of resistance spot welding model is established described in step (3), specifically:
(3.1) it is based on multiple regression analysis and least square method error criterion, establishes miniature joint for resistance spot welding quality prison Survey model A;
(3.1.1) divides the photon signal in miniature resistance spot welding process using N1 miniature resistance spot welding samples Section fitting, and according to the matched curve of least square method criterion searching photon signal;
(3.1.2) is based on N2 miniature resistance spot welding samples and verifies to the matched curve in step (3.1.1), works as survey When trying accuracy higher than setting value, the photon signal curve of qualified spot welding sample is confirmed;
(3.2) miniature joint for resistance spot welding quality-monitoring Model B is established based on combination nearest neighbour classification device KNN algorithm;
(3.2.1) is used different using N1 miniature resistance spot welding samples in the case where number of classifying determines respectively The measurement criterion of KNN algorithm, binding characteristic amount establish miniature resistance spot welding monitoring model, use N2 miniature resistance spot welding samples Different measurement criterion models are verified, record each model to the monitoring result of N2 miniature joint for resistance spot welding;
(3.2.2) gives each the monitoring accuracy of different measurement criterions according to the verification result of step (3.2.1) The different weight of disaggregated model, to optimize the accuracy rate of miniature resistance spot welding monitoring model.
When new miniature resistance spot welding characteristic quality of sample enters system, first determine whether the sample all characteristic quantities whether In initial decision threshold section all in step (2), it can directly judge that the tack-weld belongs to acceptable splice 1 or unqualified Connector 0;
If all characteristic quantities are all in the initial decision threshold interval that step (2) obtains, miniature joint for resistance spot welding Mass monitoring system output identification 1 illustrates that the miniature joint for resistance spot welding belongs to qualified sample;
If there are Partial Feature amounts not in the initial decision threshold interval of step (2) for the characteristic quantity of sample, need To the miniature resistance quality monitoring of resistance spot welding model that miniature resistance spot welding sample further utilizes step (3) to establish, micro electric is judged Hinder the credit rating of spot welding sample;When the monitoring result of miniature joint for resistance spot welding quality-monitoring model A, B are consistent, if micro- The monitoring result of type joint for resistance spot welding quality-monitoring model A, B belong to acceptable splice 1, then monitor system and export 1 automatically, such as The monitoring result of miniature joint for resistance spot welding quality-monitoring model A, the B of fruit belongs to unqualified connector 0, then it is automatically defeated to monitor system Out 0;
When the monitoring result of miniature joint for resistance spot welding quality-monitoring model A, B are inconsistent, then need for the micro electric Resistance tack-weld gives abnormality processing, reminds operator using other detection methods or manually checks the miniature resistance spot welding Whether connector meets requirement.
The beneficial effects of the present invention are: using the response time up to the highly sensitive single-photon detector monitoring of nanosecond Weld interval extremely short miniature resistance spot welding process, according to the photon in nearly nugget region with weld interval changing rule to micro electric Resistance tack-weld quality is monitored.There are correlation, tack-weld forming process and temperature fields for the variation of number of photons and temperature Closely related, the correlation of the two is that the present invention provides Important Theoretic Foundations.Present invention firstly provides be based on photon signal The characteristic quantity of point quality proposes to establish with Gaussian Profile aiming at the problem that initial decision boundary can not be set based on experience value The method combined is rejected with overlay space in the probability density space of the miniature joint for resistance spot welding of different brackets, determines initial judgement Boundary.The present invention proposes to guarantee effective detection of unqualified solder joint using the method for dual model cross validation, and establishes micro electric Hinder quality monitoring of resistance spot welding database.
Detailed description of the invention
The drawings described herein are used to provide a further understanding of the present invention, constitutes part of this application, this hair Bright illustrative example and its explanation is used to explain the present invention, and is not constituted improper limitations of the present invention.
Fig. 1 is system module flow chart of the invention;
Fig. 2 is that miniature resistance spot welding of the invention monitors system initialization interface;
Fig. 3 is that miniature resistance spot welding of the invention monitors system working interface.
Specific embodiment
Detailed content and its specific embodiment of the invention are further illustrated with reference to the accompanying drawing.
Referring to shown in Fig. 1 to Fig. 3, miniature resistance spot welding quality on-line monitoring method of the invention, when first with response Between up to nanosecond single-photon detector in miniature resistance spot welding production process electrode and workpiece engagement edge number of photons The situation that changes with time carries out real-time monitoring, draws out photon change curve;It is tested by metallographic and determines spot welding different process Under the conditions of miniature joint for resistance spot welding credit rating, since photon variation reflects the variation in temperature field to a certain extent, because Photon change curve is different in the miniature resistance spot welding process of this different quality, extracts different quality etc. using data mining means The photon characteristic quantity of the miniature joint for resistance spot welding quality of grade, generates miniature joint for resistance spot welding quality classification model, establishes base In the database of the miniature joint for resistance spot welding quality-monitoring of photon signal, miniature resistance spot welding under different technology conditions is realized Head quality automatic on-line monitoring.The present invention provides new way for the on-line monitoring of miniature resistance spot welding quality, the monochromatic light used Sub- detector is high to the detectivity of nugget change of temperature field, and improve the online quality-monitoring of miniature resistance spot welding can By property height.
Referring to shown in Fig. 1 to Fig. 3, miniature resistance spot welding quality on-line monitoring method of the invention includes the following steps:
Step (1) establishes human-machine interactive information module: for searching for whether miniature resistance quality monitoring of resistance spot welding database is deposited In the miniature resistance spot welding parameter that will be used;
Step (2), for having existed identical spot welding parameter in database, only need to be selected;
Step (3), if there is no identical technological parameter, need to input new miniature resistance spot welding process ginseng Number: workpiece material 1, workpiece material 2,1 plate thickness d of workpiece1, 2 plate thickness d of workpiece2, selection welding current mode (Pc pulse current, Ac Alternating current), electric current continue conduction time t, electrode pressure F, environment temperature T, initial model establish miniature resistance spot welding sample This number N
Step (4), in miniature resistance spot welding process, the real-time acquisition of photon signal: the list being exceedingly fast using the response time Photon detector detects the photon signal in nearly nugget region, and wherein the spectral response range of single-photon detector selects infrared waves Section;
Step (5), in photon signal monitoring process, avoid the interference of extraneous infrared waves, influence miniature resistance spot welding Quality-monitoring accuracy reduces interference of the clutter to miniature resistance quality monitoring of resistance spot welding result by three kinds of method comprehensive functions: It is filtered in monitoring device using the infrared fileter to match with single-photon detector spectral band, photon detector is obtained The photon signal taken filters out the radio-frequency component unrelated with miniature joint for resistance spot welding quality, at data by filter circuit During reason, threshold filter is carried out to the singular point signal of photonic data;
The number of photons that step (6), single-photon detector detect, which changes with time, can reflect out the variation of temperature, draw Photon signal processed is with the change curve of miniature resistance spot welding time, and wherein time interval is that welding current starts to welding current knot Beam;
A coefficient ε is introduced for the property and surface state of different materials, according to Planck law absolute black body Known to relational expression between radianting capacity and wavelength and temperature:
M (λ, T)=ε * C1λ-5/[exp(C2/λT)-1]
Wherein, λ-wavelength;T-absolute temperature;C1、C2- radiation constant.According to infrared measurement of temperature principle it is found that single-photon detecting The number of photons that survey device detects, which changes with time, can reflect out the variation of temperature, draw photon versus time curve, Wherein time interval is that welding current starts to welding current to terminate.
The selection of step (7), characteristic quantity:
(7.1) temperature of the nugget size of miniature joint for resistance spot welding, nugget interior tissue and resistance heat is closely related, will Welding current starts to the number of photons in welding current end time section to add up, and obtains total number of photons P in weld interval;
(7.2) data mining is carried out with the change curve of welding duration t to photon c, extracts and reflects miniature point of resistance The photon characteristic quantity of plumb joint quality: the number of photons c of welding current time started is respectively obtainedstart, generally with minimum number of photons Unanimously, maximum photon number cmax, transfer in photon curve number m, and each time corresponding number of photons c that transferstr1、ctr2、 ctr3.。。。。。ctrm, transfer corresponding time t twicetr1、ttr2、ttr3……ttrmAnd balancing photon number institute duration tb
(7.3) in current duration t, every 0.2ms time interval calculates separately the total number of light photons p in every time1、 p2….pn-1、pnAs characteristic quantity, wherein n=t/0.2;
(7.4) according to formula of varianceCalculate the Variance feature amount σ of each miniature resistance spot welding number of photons2, Wherein c is to change number of photons with the welding duration, and μ is that welding current started into the welding current end time, all photons Average;
(7.5) test the photon signal in simultaneously monitoring process to common quality problem in miniature resistance spot welding process, The miniature joint for resistance spot welding of different quality is obtained, by metallographic test, determines the joint quality etc. of miniature resistance spot welding sample Grade is respectively labeled as excellent 2, good 3, qualified 4, unqualified 0;
(7.6) the quality classification grade in step 7.5) is only used for point during miniature resistance spot welding quality model foundation Class, quality model in actual application by excellent 2, good 3, qualified 4 categories combinations be grade 1, i.e., it is logical to belong to qualified spot welding First 1, unqualified tack-weld is 0;
(7.7) by the characteristic quantity in step (7.1), (7.2), (7.3), (7.4) and four quality in step (7.5) etc. Grade does correlation analysis, rejects the relevant characteristic quantity of partial linear, obtains and miniature joint for resistance spot welding credit rating phase relation The biggish characteristic quantity of number.
Step (8) analyzes the characteristic quantity of acquisition, and the threshold value for obtaining each characteristic quantity is initial judgment basis:
(8.1) according to the different miniature joint for resistance spot welding credit rating of Gaussian Profile statistics (excellent 2, it is good 3, qualification 4, do not conform to Lattice 0) each characteristic quantity probability density;
(8.2) according to the different application of miniature joint for resistance spot welding, different miniature joint for resistance spot welding quality are rejected Grade (excellent 2, good 3, qualification 4, unqualified 0) each characteristic quantity probability density overlapping interval, determine that each characteristic quantity is suitably high Density section, as initial decision threshold value.
Step (9), the characteristic quantity according to obtained in step (7) about photon variation, establish miniature resistance spot welding quality Model, to guarantee miniature resistance quality monitoring of resistance spot welding accuracy rate, using the method for dual model cross validation to miniature resistance spot welding Connector is verified, during miniature joint for resistance spot welding quality-monitoring model foundation, at random by the miniature resistance of initial input Spot welding sample number N points are two parts, respectively training sample set N1 and test sample set N2:
(9.1) it is based on multiple regression analysis and least square method error criterion, establishes miniature joint for resistance spot welding quality prison Survey model A;
(9.1.1) divides the photon signal in miniature resistance spot welding process using N1 miniature resistance spot welding samples Section fitting, and according to the matched curve of least square method criterion searching photon signal;
(9.1.2) is based on N2 miniature resistance spot welding samples and verifies to the matched curve in step (9.1.1), works as survey When trying accuracy higher than setting value, the photon signal curve of qualified spot welding sample is confirmed;
(9.2) miniature joint for resistance spot welding quality-monitoring Model B is established based on combination nearest neighbour classification device KNN algorithm;
(9.2.1) is used different using N1 miniature resistance spot welding samples in the case where number of classifying determines respectively The measurement criterion of KNN algorithm:
Euclidean distance formula:
Manhatton distance:
And vector space cosine similarity:
Miniature resistance spot welding monitoring model is established in conjunction with features described above amount, using N2 miniature resistance spot welding samples to difference The verifying of measurement criterion model records each model to the monitoring result of N2 miniature joint for resistance spot welding;
(9.2.2) gives each the monitoring accuracy of different measurement criterions according to the verification result of step (9.2.1) The different weight of disaggregated model, to optimize the accuracy rate of miniature resistance spot welding monitoring model.
The monitoring model of step (10), the Decision boundaries that step (8) are obtained and step (9) foundation corresponds to technological parameter It is stored in miniature resistance spot welding monitoring system database.
When new miniature resistance spot welding characteristic quality of sample enters system, first determine whether the sample all characteristic quantities whether In initial decision threshold section all in step (8), it can directly judge that the tack-weld belongs to acceptable splice 1 or unqualified Connector 0;
If all characteristic quantities are all in the initial decision threshold interval that step (8) obtains, spot welding system output identification 1, that is, illustrate that the miniature joint for resistance spot welding belongs to qualified sample;
If there are Partial Feature amounts not in the initial decision threshold interval of step (8) for the characteristic quantity of sample, need To the miniature resistance quality monitoring of resistance spot welding model that miniature resistance spot welding sample further utilizes step (9) to establish, micro electric is judged Hinder the credit rating of spot welding sample;When the monitoring result of miniature joint for resistance spot welding quality-monitoring model A, B are consistent, if micro- The monitoring result of type joint for resistance spot welding quality-monitoring model A, B belong to acceptable splice 1, then monitor system and export 1 automatically, such as The monitoring result of miniature resistance quality monitoring of resistance spot welding model A, the B of fruit belongs to unqualified connector 0, then monitors system and export 0 automatically;
When the monitoring result of miniature resistance quality monitoring of resistance spot welding model A, B are inconsistent, then need for the miniature point of resistance Plumb joint gives abnormality processing, reminds operator using other detection methods or manually checks the miniature joint for resistance spot welding Whether requirement is met.
Embodiment 1:
With the single photon monitoring in the miniature resistance spot welding process of lithium battery series and parallel in new-energy automobile power battery group For, wherein the positive and negative extremely stainless steel case of 0.3mm of battery core, busbar connector are the nickel sheet of 0.1mm, welding current 1.5kA, weldering Connecing the time is 2ms, electrode diameter 1.5mm.Operating wavelength range is used to detect for the near-infrared single photon of 900~1700nm Device, fastest response speed are up to 10ns, and ultrared single-photon detector overall dimensions are the cylinders that radius is a height of 100mm of 50mm Body, the frequency acquisition of data acquisition module are 500Mhz.
It is shown in Figure 1, it is data acquisition and procession module flow diagram of the present invention, is entering miniature resistance spot welding single photon After monitoring system, system interface is shown in Figure 2, and interface center shows current welding material details and miniature resistance spot welding work Skill condition.
If the miniature resistance spot welding parameter that will be used does not change, clicks directly on middle button and enter prison Examining system.If using new miniature resistance spot welding parameter, need to click lower left search technological parameter by Button scans for model existing in database.
When searching the monitoring model under corresponding process conditions in the database, can directly select into monitoring state. When the monitoring model of corresponding process parameters is not present in database, technological parameter required for inputting in systems, to lithium electricity The miniature resistance spot welding process of pond series and parallel carries out single photon signal monitoring.
1) characteristic quantity of monitoring signals is chosen:
The temperature of the nugget sizes of 1.1 miniature joint for resistance spot welding, nugget interior tissue and resistance heat is closely related, from weldering It connects electric current to start to the number of photons in welding current end time section to add up, obtains total number of photons P in weld interval.
The change curve of 1.2 couples of photon c t at any time carries out data mining, extracts and reflects miniature joint for resistance spot welding quality Photon characteristic quantity: respectively obtain the number of photons c of welding current time startedstart(generally consistent with minimum number of photons), it is maximum Number of photons cmax, transfer in photon curve number m, and to each time corresponding number of photons c that transferstr1、ctr2、ctr3.。。。。。ctrm, Transfer corresponding time t twicetr1、ttr2、ttr3……ttrmAnd balancing photon number institute duration tb
1.3 in weld interval t, and every 0.2ms time interval calculates separately the total number of light photons p in every time1、p2… .pn-1、pnAs characteristic quantity, wherein n=t/0.2.
1.4 according to formula of varianceCalculate the Variance feature amount σ of each miniature resistance spot welding number of photons2, Middle c is to change number of photons with the welding duration, and μ is that welding current started into the welding current end time, all photons Average.
Common quality problem test the photon signal in simultaneously monitoring process in 1.5 pairs of miniature resistance spot welding processes, obtains The joint quality grade of miniature resistance spot welding sample is determined by metallographic test to the miniature joint for resistance spot welding of different quality, It is respectively labeled as excellent 2, good 3, qualified 4, unqualified 0.
1.6 it is above-mentioned 1.5) in quality classification grade be only used for point during miniature resistance spot welding quality model foundation Class, quality model in actual application by excellent 2, good 3, qualified 4 categories combinations be grade 1, i.e., it is logical to belong to qualified spot welding First 1, unqualified tack-weld is 0.
1.7 by it is above-mentioned 1.1) 1.2) 1.3) 1.4) in each characteristic quantity to it is above-mentioned 7.5) in four credit ratings do it is related Property analysis, reject the relevant characteristic quantity of partial linear, obtain biggish with miniature joint for resistance spot welding credit rating related coefficient Characteristic quantity.
2) above-mentioned 1) the middle characteristic quantity obtained is analyzed, the threshold value for obtaining each characteristic quantity is initial judgment basis:
2.1 according to the different miniature joint for resistance spot welding credit rating of Gaussian Profile statistics (excellent 2, it is good 3, qualification 4, unqualified 0) each characteristic quantity is in probability density.
2.2, according to the different application of miniature joint for resistance spot welding, reject different miniature joint for resistance spot welding quality etc. Grade (excellent 2, good 3, qualification 4, unqualified 0) each characteristic quantity probability density overlapping interval, determine that each characteristic quantity is suitably highly dense Section is spent, as initial decision threshold value.
3) the various characteristic quantities about photon variation according to obtained in 1), establish miniature resistance spot welding quality model, are Guarantee that miniature resistance quality monitoring of resistance spot welding accuracy rate, the present invention are spot welded miniature resistance using the method for dual model cross validation Head, during miniature joint for resistance spot welding quality-monitoring model foundation, at random by the miniature resistance spot welding sample number N of initial input It is divided into two parts, respectively training sample set N1 and test sample set N2:
3.1 are based on multiple regression analysis and least square method error criterion, establish miniature joint for resistance spot welding quality-monitoring Model A.
3.1.1 using N1 miniature resistance spot welding samples, the photon signal in miniature resistance spot welding process is segmented Fitting, and according to the matched curve of the photon signal under least square method criterion searching specific process conditions.
3.1.2 the matched curve in 3.1.1 is verified based on N2 miniature resistance spot welding samples, works as test accuracy When higher than setting value, the photon signal curve of qualified spot welding sample is confirmed.
3.2 establish miniature joint for resistance spot welding quality-monitoring Model B based on combination KNN (nearest neighbour classification device) algorithm.
3.2.1 using N1 miniature resistance spot welding samples, in the case where number of classifying determines, respectively using different The measurement criterion of KNN algorithm establishes miniature resistance spot welding monitoring model in conjunction with features described above amount, uses N2 miniature resistance spot weldings Sample verifies different measurement criterion models, records each model to the monitoring result of N2 miniature joint for resistance spot welding.
3.2.2 this point is given for the monitoring accuracy of different each measurement criterions according to the verification result of above-mentioned 3.2.1 The different weight of class model, to optimize the accuracy rate of miniature resistance spot welding monitoring model.
4) by above-mentioned steps 2) obtain Decision boundaries and above-mentioned steps 3) establish monitoring model correspond to technological parameter It is stored in miniature resistance spot welding monitoring system database.
5) when new miniature each characteristic quantity of resistance spot welding sample enters system, all characteristic quantities of the sample are first determined whether Whether all in above-mentioned steps 8) in initial decision threshold section in, can directly judge that the tack-weld belongs to acceptable splice 1 or unqualified connector 0.
If 6) all characteristic quantities are all in above-mentioned steps 2) in obtained initial decision threshold interval, spot welding system output Mark 1, that is, illustrate that the miniature joint for resistance spot welding belongs to qualified sample.
If 7) there are Partial Feature amounts not in above-mentioned steps 2 for the characteristic quantity of the sample) in initial decision threshold interval Interior, then need further to utilize above-mentioned steps 3 to the miniature resistance spot welding sample) in the miniature resistance quality monitoring of resistance spot welding established Model judges the credit rating of the miniature resistance spot welding sample.When the monitoring result of model A, B are consistent, if model A, B Monitoring result monitoring belongs to acceptable splice 1, then monitors system and export 1 automatically, if the monitoring result of model A, B belong to not Acceptable splice 0 then monitors system and exports 0 automatically.
It when the monitoring result of model A, B are inconsistent, then needs to give abnormality processing to the miniature resistance spot welding, reminds behaviour Make personnel using other detection methods or manually checks whether the tack-weld meets requirement.
The foregoing is merely preferred embodiments of the invention, are not intended to restrict the invention, for the technology of this field For personnel, the invention may be variously modified and varied.All any modification, equivalent substitution, improvement and etc. made for the present invention, It should all be included in the protection scope of the present invention.

Claims (5)

1. a kind of miniature resistance spot welding quality on-line monitoring method, it is characterised in that: first with single-photon detector to miniature The number of photons of electrode in the resistance spot welding production process and workpiece engagement edge situation that changes with time carries out real-time monitoring, draws Produce photon change curve;It is tested by metallographic and determines miniature joint for resistance spot welding credit rating under spot welding different technology conditions, Photon change curve is different in the miniature resistance spot welding process of different quality, extracts different quality grade using data mining means Miniature resistance spot welding quality photon characteristic quantity, generate miniature resistance spot welding quality disaggregated model, establish and be based on photon signal Miniature resistance quality monitoring of resistance spot welding database, realize miniature resistance spot welding quality automatic on-line prison under different technology conditions It surveys;Specifically comprise the following steps:
Selection of the step (1) to the characteristic quantity of photon signal;
Step (2) analyzes the characteristic quantity of acquisition, and the threshold value for obtaining each characteristic quantity is initial judgment basis;
Step (3), the characteristic quantity according to obtained in step (1) about photon variation, establish miniature resistance spot welding quality model, To guarantee miniature resistance quality monitoring of resistance spot welding accuracy rate, using dual model cross validation method to miniature resistance spot welding quality into Row monitoring;During miniature resistance quality monitoring of resistance spot welding model foundation, at random by the miniature resistance spot welding sample number N of initial input It is divided into two parts, respectively training sample set N1 and test sample set N2;
The monitoring model of step (4), the Decision boundaries that step (2) are obtained and step (3) foundation is stored in corresponding to technological parameter Miniature resistance spot welding monitors system database.
2. miniature resistance spot welding quality on-line monitoring method according to claim 1, it is characterised in that: step (1) is described The selection of the characteristic quantity to monitoring signals be:
(1.1) welding current is started to the number of photons in welding current end time section to add up, is obtained in weld interval Total number of photons P;
(1.2) data mining is carried out with the change curve of weld interval t to number of photons c, extracts and reflects miniature joint for resistance spot welding The photon characteristic quantity of quality: the number of photons c of welding current time started is respectively obtainedstart, it is generally consistent with minimum number of photons, most Big number of photons cmax, transfer in photon curve number m, and each time corresponding number of photons c that transferstr1、ctr2、ctr3.。。。。。ctrm, Transfer corresponding time t twicetr1、ttr2、ttr3……ttrmAnd balancing photon number institute duration tb
(1.3) in current duration t, every 0.2ms time interval calculates separately the total number of light photons c in every time1、c2… .cn-1、cnAs characteristic quantity, wherein n=t/0.2;
(1.4) according to formula of varianceCalculate the Variance feature amount σ of each miniature resistance spot welding number of photons2, wherein C is to change number of photons with weld interval t, and μ is that welding current started into the welding current end time, and all photons are averaged Number;
(1.5) test the photon signal in simultaneously monitoring process to common quality problem in miniature resistance spot welding process, obtain The miniature joint for resistance spot welding of different quality determines the joint quality grade of miniature resistance spot welding sample by metallographic test, point It is not labeled as excellent 2, good 3, qualified 4, unqualified 0;
(1.6) the quality classification grade in step (1.5) is only used for the classification during miniature resistance spot welding quality model foundation, Quality model in actual application by excellent 2, good 3, qualified 4 categories combinations be grade 1, i.e., it is logical to belong to qualified tack-weld 1, Unqualified tack-weld is 0;
(1.7) characteristic quantity in step (1.1), (1.2), (1.3), (1.4) is done with four credit ratings in step (1.5) Correlation analysis rejects the relevant characteristic quantity of partial linear, obtain with miniature joint for resistance spot welding credit rating related coefficient compared with Big characteristic quantity.
3. miniature resistance spot welding quality on-line monitoring method according to claim 1, it is characterised in that: step (2) is described The characteristic quantity of acquisition is analyzed, obtain each characteristic quantity threshold value be initial judgment basis, specifically:
(2.1) according to the probability density of each characteristic quantity of the different miniature joint for resistance spot welding credit ratings of Gaussian Profile statistics;
(2.2) according to the different application of miniature joint for resistance spot welding, different miniature joint for resistance spot welding credit ratings are rejected Each characteristic quantity probability density overlapping interval, between determining the suitable high density area of each characteristic quantity, as initial decision threshold value;
Above-mentioned credit rating is: excellent 2, good 3, qualification 4, unqualified 0.
4. miniature resistance spot welding quality on-line monitoring method according to claim 1, it is characterised in that: step (3) is described Establish miniature resistance quality monitoring of resistance spot welding model, specifically:
(3.1) it is based on multiple regression analysis and least square method error criterion, establishes miniature joint for resistance spot welding quality-monitoring mould Type A;
(3.1.1) carries out segmentation to the photon signal in miniature resistance spot welding process and intends using N1 miniature resistance spot welding samples It closes, and finds the matched curve of photon signal according to least square method criterion;
(3.1.2) is based on N2 miniature resistance spot welding samples and verifies to the matched curve in step (3.1.1), when test is quasi- When exactness is higher than setting value, the photon signal curve of qualified spot welding sample is confirmed;
(3.2) miniature joint for resistance spot welding quality-monitoring Model B is established based on combination nearest neighbour classification device KNN algorithm;
(3.2.1) uses different KNN in the case where number of classifying determines using N1 miniature resistance spot welding samples respectively The measurement criterion of algorithm, binding characteristic amount establish miniature resistance spot welding monitoring model, use N2 miniature resistance spot welding samples pair Different measurement criterion model verifyings, record each model to the monitoring result of N2 miniature joint for resistance spot welding;
(3.2.2) gives each classification for the monitoring accuracy of different measurement criterions according to the verification result of step (3.2.1) The different weight of model, to optimize the accuracy rate of miniature resistance spot welding monitoring model.
5. miniature resistance spot welding quality on-line monitoring method according to any one of claim 1 to 4, it is characterised in that: When new miniature resistance spot welding characteristic quality of sample enters system, first determine whether all characteristic quantities of the sample whether all in step (2) in the initial decision threshold section in, it can directly judge that the tack-weld belongs to acceptable splice 1 or unqualified connector 0;
If all characteristic quantities are all in the initial decision threshold interval that step (2) obtains, miniature joint for resistance spot welding quality Monitoring system output identification 1 illustrates that the miniature joint for resistance spot welding belongs to qualified sample;
If there are Partial Feature amounts not in the initial decision threshold interval of step (2) for the characteristic quantity of sample, need to micro- The miniature resistance quality monitoring of resistance spot welding model that type resistance spot welding sample further utilizes step (3) to establish, judges miniature point of resistance Weld the credit rating of sample;When the monitoring result of miniature joint for resistance spot welding quality-monitoring model A, B are consistent, if micro electric The monitoring result of resistance tack-weld quality-monitoring model A, B belong to acceptable splice 1, then monitor system and export 1 automatically, if micro- The monitoring result of type joint for resistance spot welding quality-monitoring model A, B belong to unqualified connector 0, then monitor system and export 0 automatically;
When the monitoring result of miniature joint for resistance spot welding quality-monitoring model A, B are inconsistent, then need for the miniature point of resistance Plumb joint gives abnormality processing, reminds operator using other detection methods or manually checks the miniature joint for resistance spot welding Whether requirement is met.
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