CN104677751A - Quality detection method for resistance-spot-welding spots on basis of calculation of thermal effect of welding process - Google Patents

Quality detection method for resistance-spot-welding spots on basis of calculation of thermal effect of welding process Download PDF

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CN104677751A
CN104677751A CN201510091370.5A CN201510091370A CN104677751A CN 104677751 A CN104677751 A CN 104677751A CN 201510091370 A CN201510091370 A CN 201510091370A CN 104677751 A CN104677751 A CN 104677751A
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welding
spot
thermal effect
resistance
solder joint
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CN104677751B (en
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罗怡
樊红军
高飞
刘伟
章璇
段钰婷
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Chongqing University of Technology
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Abstract

The invention discloses a quality detection method for resistance-spot-welding spots on the basis of calculation of the thermal effect of a welding process. The method comprises the following steps: calculating the thermal effect generated in the welding-spot forming process by means of welding current signals, electrode voltage signals and welding-current duration time detected in the process of resistance spot welding in real time, and drawing a relation curve on the basis of the welding thermal effect obtained by calculation and the welding-spot diameter and the maximum welding-spot bearing capacity detected corresponding to the welding-spot destructiveness so as to establish a mathematical model of the thermal effect and the welding-spot diameter and a mathematical model of the thermal effect and the maximum welding-spot bearing capacity; establishing a database of mathematical models for the quality of the resistance-spot-welding spots with different thicknesses and different materials in a computer system; and in the practical welding process, calling corresponding mathematical models in the database, inputting the thermal-effect value obtained by detection, then calculating and outputting the diameter values and maximum bearing capacity values of the welding spots by the computer system, and if the values are less than corresponding set threshold values, judging that the welding spots are unqualified. The quality detection method has the advantages that the nondestructive detection and evaluation of the diameters and the maximum bearing capacities of the resistance-spot-welding spots can be quickly realized, so that the quality detection method is especially suitable for online quality detection on a welding production site.

Description

A kind of resistance spot welding quality of welding spot detection method calculated based on welding process thermal effect
Technical field
The present invention relates to a kind of method of the welding effect assessment resistance spot welding quality of welding spot utilizing welding process to calculate, be applicable to the quality of welding spot assessment of common metal thin-plate structure muterial, be particularly useful for production scene online quality control.
Background technology
Resistance spot welding is a kind of welding method being widely used in automobile making, in the vehicle body metal construction welding of Modern Car, obtain extensive application.Therefore, the detection of resistance spot welding quality of welding spot is extremely important, in welding process expeditiously butt welding point quality carry out sensing and check and evaluation for enhance productivity and welding quality, save production cost significant.But in resistance spot welding process, the formation of solder joint is hidden among workpiece, can not directly be observed, this carries out real-time sensing for welding quality and online evaluation quality of welding spot brings difficulty.Therefore, in manufacturing enterprise, all need to extract certain proportion to the welded structure product produced according to quality inspection at postwelding under normal circumstances, and carry out destructive test detection.Detect mainly for spot size and these two important indicators of solder joint maximum load capacity.Wherein, detecting spot size needs to tear solder joint welded structure, measures its macro-size; Detect solder joint maximum load capacity, need to carry out tensile-sbear strength test.Such detection method not only inefficiency, adds production cost, and can not ensure the reliability of non-testing product.Therefore, in resistance spot welding process, the sensing of quality of welding spot information has great importance for utilizing lossless detection method online evaluation resistance spot welding quality of welding spot.For this reason, researcher adopts multiple method to detect solder joint to characterize its quality.
The real-time detection method of dot weld nugget diameter disclosed in Chinese patent literature CN1609622A adopts following steps: get and carry out multiple spot welding with the welded specimen of weldment same thickness, obtained the dynamic resistance curve of often by surveying and calculating; And then obtain the metastable state resistance value r of often d; Cut welded specimen open along binding face, measure the nugget size d of each solder joint core; According to each nugget diameter d corewith metastable state resistance value r dcorresponding relation, draw out metastable state resistance value r dwith nugget size d corerelation curve; By the r of different-thickness material d-d corein computer systems, which, when certain material of spot welding, computer system first obtains the metastable state resistance value r of this solder joint to profile memory d, then with the r of same thickness material d-d corecurve compares and can obtain corresponding nugget size, when nugget size is less than the standard value of setting, judges that quality of welding spot is defective, realizes detecting in real time.
Aluminium alloy resistance spot welding nugget size real-time detection method disclosed in Chinese patent literature CN101241001A adopts following steps: gather the electrode displacement signals during resistance in pinpoint welding procedure, and draw out electrode displacement signals during resistance curve map; Expansion displacement and forging and stamping displacement two eigenwerts are extracted from the electrode displacement signals during resistance curve of gained; Welded test plate (panel) is torn, nugget formation in resistance spot welding diameter is surveyed, set up the sample pair that the eigenwert extracted is corresponding with the nugget size of actual measurement, and form training set; Set up artificial nerve network model, and train according to BP algorithm to model with gained sample, realize the mapping from eigenwert to nugget size; Artificial nerve network model is two inputs, an output, a middle hidden layer, and the number of hidden layer node is the structure of 5, and the transfer function of hidden layer is Sigmoid function, and the transfer function of output layer is linear function; The model trained is used for the on-line real-time measuremen of aluminium alloy resistance spot welding nugget size.
The method of multi-information merging technology determination aluminum alloy plate materials nugget formation in resistance spot welding area disclosed in Chinese patent literature CN1220034C adopts following steps: according to wavelet package transforms and energy spectrum principle, foundation information entropy principle, foundation model analysis principle, calculate the characteristic quantity of electrode voltage in pinpoint welding procedure, electric current, electrode displacement and voice signal, set up neural network model, by characteristic quantity and nugget area, neural network model is trained.The nugget area that neural network model calculates contrasts with actual measurement nugget area, determines error amount, and adjustment neural network model, until reach error requirements scope.
In resistance spot welding process, solder joint forms the resistance heat effect that required energy produces primarily of welding process and provides.Resistance heat effect then produces primarily of the welding current flowing through secondary circuit, and along with the change of solder joint forming process, the electrode voltage at solder joint two ends also corresponding change can occur.Therefore, the resistance heat effect utilizing the accumulated time effect of welding current and electrode voltage product can calculate solder joint forming process to produce.Shown in (1):
Q = ∫ t 0 t 1 U ( t ) · I ( t ) dt - - - ( 1 )
Wherein, Q is resistance heat effect, the change that U (t) is electrode voltage, the change that I (t) is welding current, and the welding current duration is t 1-t 0.Visible, realize the real-time detection of resistance spot welding process thermal effect and be calculated as the online sensing of resistance spot welding quality of welding spot information and assessment provides possibility.
Summary of the invention
The present invention is directed to the resistance spot welding of common metal thin-plate structure muterial, a kind of quality of welding spot detection method calculated based on welding process thermal effect is provided, the method adopts the welding current in close relations with solder joint forming process, electrode voltage is information source, therefore, testing result is reliable, testing cost consumes low, and is especially applicable to the online quality control at welding production scene.
The present invention takes following technical scheme:
A kind of resistance spot welding quality of welding spot detection method calculated based on welding process thermal effect, the thermal effect that the method produces by the welding current signal detected in real time in resistance spot welding welding process, electrode voltage signal and welding current Time Calculation solder joint forming process, and utilize thermal effect detection, assessment resistance spot welding welding spot size and solder joint maximum load capacity, the step of described detection method is as follows:
(1) setting is no less than 15 bond pads electric currents, welding current duration, welding foroe parameter carry out resistance spot welding, to the resistance spot welding process welding current signal in each welding process Real-time Collection resistance spot weld secondary loop and electrode voltage signal;
(2) draw out welding current and the time dependent signal waveform of electrode voltage in computer systems, which, check waveform fluctuation amplitude and the reliability in cycle;
(3) utilize computer system to do multiplying to welding current signal, electrode voltage signal waveform, and do definite integral computing based on the welding current duration, obtain welding process thermal effect numerical value;
(4) being detected the diameter obtaining above-mentioned each bond pads technological parameter welding gained solder joint by intercepting solder joint xsect, cutting experiment acquisition solder joint maximum load capacity by drawing;
(5) with the welding process thermal effect numerical value calculated for X-axis, the spot size obtained with detection or maximum load capacity are for Y-axis, utilize computer system to draw out relation curve, and matching obtain thermal effect-spot size mathematical model or thermal effect-solder joint maximum load capacity mathematical model;
(6) the resistance spot welding quality of welding spot mathematical model database of different-thickness, different materials is set up in computer systems, which according to above-mentioned steps;
(7) according to the quality control standards (QCS) adopted, the resistance spot welding spot size reference threshold of setting different-thickness, different materials and maximum load capacity reference threshold;
(8) in actual welding process, call corresponding mathematical model in a database, input detects the thermal effect numerical value obtained, and namely computer system calculates and export spot size value and maximum load capacity value, set threshold value accordingly as being less than, this solder joint is judged as defective.
Innovation of the present invention is the resistance spot welding process welding current that real-time monitors and electrode voltage calculates the thermal effect obtaining solder joint forming process and produce as information source, by setting up the relational model between welding effect and spot size, solder joint maximum load capacity, realize quick, the Non-Destructive Testing to resistance spot welding spot size and maximum load capacity and assessment.
The present invention is applicable to the on-the-spot on-line quick detection of welding production and evaluation resistance spot welding quality of welding spot information.Compared with prior art, the present invention has the following advantages:
(1) information source adopted---welding current and electrode voltage and solder joint forming process in close relations, the welding effect calculated and quality of welding spot correlativity strong, make testing result reliability high;
(2) signal detection system easily realizes, and system manufacturing cost is comparatively cheap;
(3) can detect quality of welding spot information fastly, form the assessment to resistance spot welding process and quality, applicable material ranges is comparatively wide, and practicality is stronger;
(4) detection efficiency is high, and assessment method is simple, is applicable to online quality control and the grade estimation of resistance spot welding production scene.
Accompanying drawing explanation
Fig. 1 is the welding current signal waveform of the low-carbon steel plate resistance spot welding process that embodiment 1 detects.
Fig. 2 is the electrode voltage signal waveform of the low-carbon steel plate resistance spot welding process that embodiment 1 detects.
Fig. 3 is that embodiment 1 destructiveness detects the nugget macro morphology obtained.
Fig. 4 is that embodiment 1 destructiveness detects the solder joint that obtains and draws and cut mechanical curves.。
Fig. 5 is the welding effect and spot size relation curve set up
Fig. 6 is the welding effect and solder joint maximum load capacity relation curve set up.
Fig. 7 is the welding current signal waveform of the low-carbon steel plate resistance spot welding process that embodiment 2 detects.
Fig. 8 is the electrode voltage signal waveform of the low-carbon steel plate resistance spot welding process that embodiment 2 detects.
Fig. 9 is that embodiment 2 destructiveness detects the nugget macro morphology obtained.
Figure 10 is that embodiment 2 destructiveness detects the solder joint that obtains and draws and cut mechanical curves.
Embodiment
Below in conjunction with specific embodiment, set forth the present invention further.
Embodiment 1:
Workpiece to be welded is the overlap joint of the low-carbon steel material thin-slab construction of two pieces of thickness 1mm.The major weld process parameters adopted is: welding current is 6000A, and the welding current duration is 0.28s, and welding foroe is 0.15MPa.
In welding, the welding current signal of Real-time Collection resistance spot welding process and electrode voltage signal, draw signal waveforms by analysis software, respectively as depicted in figs. 1 and 2.
The welding effect produced by this welding technology of Definite Integral Calculation is 23.231kJ.
Adopt 15 groups of different welding conditions to carry out welding and testing, wherein, welding current is 4500A ~ 8000A, and welding foroe is 0.1MPa ~ 0.2MPa, and the welding current duration is 0.16s ~ 0.38s.According to detecting the welding current and electrode voltage that obtain in real time, calculate the welding effect that 15 bond pads techniques form solder joint.Spot size and the detection of maximum load capacity destructiveness are carried out respectively to each group of solder joint obtained.Set up welding effect and spot size, solder joint maximum load capacity relation curve as shown in Figure 5 and Figure 6.Wherein, according to the relation in Fig. 5, matching obtains thermal effect-spot size mathematical model and is: D=6.241-3.371 × 10 -4q+1.076 × 10 -8q 2; According to the relation in Fig. 6, the thermal effect that matching obtains-solder joint maximum load capacity mathematical model is: F=5.319-2982.749exp (-Q/2367.085).
Mathematical model according to setting up calculates 4.217mm to the spot size in embodiment 1, and measured diameter is 4.014mm, and as shown in Figure 3, error is 5.06% to solder joint nucleation; Butt welding point maximum load capacity carries out calculating 5.15kN, and actual measurement draws shearing load to be 4.92kN, and solder joint destructiveness detects drawing of obtaining and cuts mechanical curves as shown in Figure 4, and error is 4.67%.
This result shows, utilizes the method for the invention can realize non-damaged data to resistance spot welding spot size and maximum load capacity and assessment comparatively accurately and quickly.
Embodiment 2:
Workpiece to be welded is the overlap joint of the low-carbon steel material thin-slab construction of two pieces of thickness 1mm.The major weld process parameters adopted is: welding current is 4500A, and the welding current duration is 0.24s, and welding foroe is 0.15MPa.
In welding, the welding current signal of Real-time Collection resistance spot welding process and electrode voltage signal, draw signal waveforms by analysis software, respectively as shown in Figure 7 and Figure 8.
The welding effect produced by this welding technology of Definite Integral Calculation is 16.281kJ.
Adopt 15 groups of different welding conditions to carry out welding and testing, wherein, welding current is 4500A ~ 8000A, and welding foroe is 0.1MPa ~ 0.2MPa, and the welding current duration is 0.16s ~ 0.38s.According to detecting the welding current and electrode voltage that obtain in real time, calculate the welding effect that 15 bond pads techniques form solder joint.Spot size and the detection of maximum load capacity destructiveness are carried out respectively to each group of solder joint obtained.Set up welding effect and spot size, solder joint maximum load capacity relation curve as shown in Figure 5 and Figure 6.Wherein, according to the relation in Fig. 5, matching obtains thermal effect-spot size mathematical model and is: D=6.241-3.371 × 10 -4q+1.076 × 10 -8q 2; According to the relation in Fig. 6, the thermal effect that matching obtains-solder joint maximum load capacity mathematical model is: F=5.319-2982.749exp (-Q/2367.085).
Mathematical model according to setting up calculates 3.605mm to the spot size in embodiment 2, and measured diameter is 3.779mm, and error is 4.60%; Butt welding point maximum load capacity carries out calculating 2.246kN, and actual measurement draws shearing load to be 2.382kN, and error is 5.71%.
This result shows, utilizes the method for the invention can realize non-damaged data to resistance spot welding spot size and maximum load capacity and assessment comparatively accurately and quickly.

Claims (1)

1. the resistance spot welding quality of welding spot detection method calculated based on welding process thermal effect, the thermal effect that the method produces by the welding current signal detected in real time in resistance spot welding welding process, electrode voltage signal and welding current Time Calculation solder joint forming process, and utilize thermal effect detection, assessment resistance spot welding welding spot size and solder joint maximum load capacity, the step of described detection method is as follows:
(1) for different materials different-thickness, setting is no less than 15 bond pads electric currents respectively, welding current duration, welding foroe parameter carry out resistance spot welding, to the resistance spot welding process welding current signal in each welding process Real-time Collection resistance spot weld secondary loop and electrode voltage signal;
(2) draw out welding current and the time dependent signal waveform of electrode voltage in computer systems, which, check waveform fluctuation amplitude and the reliability in cycle;
(3) utilize computer system to do multiplying to welding current signal, electrode voltage signal waveform, and do definite integral computing based on the welding current duration, obtain welding process thermal effect numerical value;
(4) being detected the diameter obtaining above-mentioned each bond pads technological parameter welding gained solder joint by intercepting solder joint xsect, cutting experiment acquisition solder joint maximum load capacity by drawing;
(5) with the welding process thermal effect numerical value calculated for X-axis, the spot size obtained with detection or maximum load capacity are for Y-axis, utilize computer system to draw out relation curve, and matching obtain thermal effect-spot size mathematical model or thermal effect-solder joint maximum load capacity mathematical model;
(6) the resistance spot welding quality of welding spot mathematical model database of different-thickness, different materials is set up in computer systems, which according to above-mentioned steps;
(7) according to the quality control standards (QCS) adopted, the resistance spot welding spot size reference threshold of setting different-thickness, different materials and maximum load capacity reference threshold;
(8) in actual welding process, call corresponding mathematical model in a database, input detects the thermal effect numerical value obtained, and namely computer system calculates and export spot size value and maximum load capacity value, set threshold value accordingly as being less than, this solder joint is judged as defective.
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CN107745176A (en) * 2017-10-31 2018-03-02 天津七所高科技有限公司 A kind of resistance spot welding control method and system for exempting from parameter setting
CN108535660A (en) * 2018-04-26 2018-09-14 深圳市泰欣能源科技有限公司 The detection device and its detection method of a kind of group of battery modules junction conduction
CN109409520A (en) * 2018-10-17 2019-03-01 深圳市微埃智能科技有限公司 Welding condition recommended method, device and robot based on transfer learning
CN112529884A (en) * 2020-12-17 2021-03-19 中国石油大学(华东) Welding spot quality evaluation method based on indentation characteristic image recognition
CN115178845A (en) * 2021-04-06 2022-10-14 上海汽车集团股份有限公司 Calculation method of welding parameters of resistance spot welding and welding parameter control system
CN113977056A (en) * 2021-10-27 2022-01-28 重庆理工大学 Secondary current pulse-based resistance spot welding spot quality detection method
CN113977056B (en) * 2021-10-27 2022-12-27 重庆理工大学 Secondary current pulse-based resistance spot welding spot quality detection method
CN114918537A (en) * 2022-05-20 2022-08-19 泰德激光惠州有限公司 Welding method of vapor chamber and middle frame, laser processing equipment and heat dissipation structure

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