• Title/Summary/Keyword: Resistance spot weld

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Weld Quality Assurance Method using Statistical Analysis of Primary Dynamic Resistance During Resistance Spot Welding (1차 동저항 패턴의 통계적 분석에 의한 저항 점 용접의 용접 품질 예측에 관한 연구)

  • Jo, Yong-Jun;Lee, Se-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.10 s.181
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    • pp.2581-2588
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    • 2000
  • In previous studies, the dynamic resistance, which was calculated by the process variables measured at the electrode of the welding machine, and the electrode displacement were used for quality exa mination. However, in-process usage of such systems is not effective in systems that include a welding gun attached to a robot. In order to overcome such problems, we obtained and used the process variables from the welding machine timer. This would allow us to estimate real time in -process weld quality. For quality estimation, the features were extracted as factors from the primary dynamic resistance patterns, which were measured in t he welding machine timer. The relationship between the indexes and nugget size of the welds was observed through the regression analysis. Using the analyzed factors, a regression model that could estimate nugget diameter was developed. Two regression equations of the model were suggested depending on the factors, and it was showed that the model developed by stepwise method was effective one for weld quality estimation. The developed estimation model was in good linearity with the nugget diameter obtained through the experimentation.

Intelligent quality estimation system using primary circuit variables of RSW (저항점용접 1차 공정변수를 이용한 지능형 용접품질 판단 시스템)

  • 조용준;이세헌;신현일;배경민;권태용
    • Proceedings of the KWS Conference
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    • 1999.10a
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    • pp.142-145
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    • 1999
  • The dynamic resistance monitoring is one of the important issues in that in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. Secondary dynamic resistance patterns, as a real manner, are hard to adapt those factors in real time and in-plant system. In the present study, a new dynamic resistance detecting method is presented as a practical manner of weld quality assurance at the primary circuit. By the correlation analysis, it is found that the primary dynamic resistance patterns are basically similar to those of the secondary. Various dynamic resistance indices are characterized with the primary curve. And quality of the weld, like the tensile shear strength, is estimated using adaptive neuro-fuzzy estimation system which is consisted of the Sugeno fuzzy algorithm. Through the fuzzy clustering and parameter optimization, real time weld quality assurance system with less efforts is proposed.

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Implementation of Dynamic Resistance Database for Weld Quality Improvement of Inverter Spot Welder (인버터 스폿용접기의 용접품질 향상을 위한 동저항 데이터베이스 구축)

  • 김재문;원충연;최규하;김규식;목형수
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.3
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    • pp.294-303
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    • 1999
  • Resistance spot welding is commonly used for welding products of high quality because of clean welding and short w welding-time. But. conventional spot welders bring about the depreciation of welding products, iuespective of dynamic r resistance characteristics during welding time. This paper discussed dynamic resistance database implementation in t terms of welding performance improvement. On different welding conditions, we compared dynamic resistance, r respectively, about pure iron and Sn-Pb alloy on Copper. Also, it investigated the relation of tensile shear strength and d dynamic resistance in welded workpiece.

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The Quality Evaluation on Resistance Spot Welding of 2024 Aluminum Alloy and Zinc Coated Steel (2024 Al합금과 아연도금강판의 점용접에 관한 품질평가)

  • 허인호;이철구;채병대
    • Journal of Welding and Joining
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    • v.19 no.4
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    • pp.379-383
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    • 2001
  • Resistance spot welding has been widely used in the sheet metal joining processes because of low cost, high productivity and convenience. Recently, automobile and aerospace industries are trying to replace partly steel sheets with aluminum alloy sheets. But in the case of dissimilar materials, to apply resistance spot welding has been known to be very difficult owing to the effect of melting temperature. On this study, an effort was made to apply spot welding of dissimilar sheet metals, 2024 aluminum alloy and zinc coated steel sheet, evaluate the spot weld quality with tensile-shear strength test and nondestructive evaluation technique, C-scan image methodology. In this study results, as the current below 11 kA, melting of materials is not achieved well. Also as the current exceeds to 13.5 kA, the more spatters happen at welded zone and tensile-shear strength lowered. So, the feasibility of C-scan image technique proposed in the study is found to be suitable evaluation method for resistance spot weldability.

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Effect of Spot Welding Conditions on Spatter and Mechanical Strength Properties (스패터 및 기계적 강도특성에 미치는 점용접 조건의 영향)

  • 서도원;윤호철;전양배;임재규
    • Journal of Welding and Joining
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    • v.21 no.2
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    • pp.70-75
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    • 2003
  • Spot welding is a process that sheet metals are joined in one or more spot by heating at the faying interface. In this process, the spatter is dispersed from melted area. It has been reported that spatter generation has adverse effects on weld quality. However, no systematic study has been carried out to find out its effect on weld quality in resistance spot welding processes. In this study, specially designed specimen are used to perform experimental investigation of spatter generation and its effect. Major finding of this study show trends in tensile-shear strength for various amounts of spatter generated during spot welding process. Thus, optimum welding conditions are proposed in view of spatter generation and tensile-shear strength. (Received December 11, 2002)

Parameter Design and Analysis for Aluminum Resistance Spot Welding

  • Cho, Yong-Joon;Li, Wei;Hu, S. Jack
    • Journal of Welding and Joining
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    • v.20 no.2
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    • pp.102-108
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    • 2002
  • Resistance spot welding of aluminum alloys is based upon Joule heating of the components by passing a large current in a short duration. Since aluminum alloys have the potential to replace steels fur automobile body assemblies, it is important to study the process robustness of aluminum spot welding process. In order to evaluate the effects of process parameters on the weld quality, major process variables and abnormal process conditions were selected and analyzed. A newly developed two-stage, sliding-level experiment was adopted fur effective parameter design and analysis. Suitable ranges of welding current and button diameters were obtained through the experiment. The effects of the factors and their levels on the variation of acceptable welding current were considered in terms of main effects. From the results, it is concluded that any abnormal process condition decreases the suitable current range in the weld lobe curve. Pareto analysis of variance was also introduced to estimate the significant factors on the signal-to-noise (S/N) ratio. Among the six factors studied, fit-up condition is found to be the most significant factor influencing the SM ratio. Using a Pareto diagram, the optimal condition is determined and the SM ratio is significantly improved using the optimal condition.

A Study on Anti-Oxidation of Stainless Steel Spot Weld (스테인리스강 Spot 용접부의 산화방지에 관한 연구)

  • Huh, Dong-Woon;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • v.29 no.5
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    • pp.58-62
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    • 2011
  • Stainless steels are alloy steels with a nominal chromium content of at least 11 percent, with other alloy additions. The stainlessness and corrosion resistance of these alloy steels are attributed to the presence of a passive oxide film on the surface. When exposed to conditions like Resistance Spot Welding (RSW) process that remove the passive oxide film, stainless steels are subject to corrosive attack. And exposure to elevated temperatures causes oxidation (discoloration) of areas around indentation in Spot welding. In this paper, deal with the effect of shielding gas (Ar) preventing the corrosion, oxidation of stainless steel. And find the optimal shielding gas flow rate. In addition, suggest effective purging method for direct/indirect spot welding process.

Optimization of Resistance Spot Weld Condition for Single Lap Joint of Hot Stamped 22MnB5 by Taking Heating Temperature and Heating Time into Consideration (핫스템핑 공정에서 가열온도 및 유지시간을 고려한 22MnB5의 단일겹치기 저항 점용접 조건 최적화)

  • Choi, Hong-Seok;Kim, Byung-Min;Park, Geun-Hwan;Lim, Woo-Seung;Lee, Sun-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1367-1375
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    • 2010
  • In this study, optimization of the process parameters of the resistance spot welding of a sheet of aluminum-coated boron alloyed steel, 22MnB5, used in hot stamping has been performed by a Taguchi method to increase the strength of the weld joint. The process parameters selected were current, electrode force, and weld time. The heating temperature and heating time of 22MnB5 are considered to be noise factors. It was known that the variation in the thickness of the intermetallic compound layer between the aluminum-coated layer and the substrate, which influences on the formation of nugget, was generated due to the difference of diffusion reaction according to heating conditions. From the results of spot weld experiment, the optimum weld condition was determined to be when the current, electrode force, and weld time were 8kA, 4kN, and 18 cycles, respectively. The result of a test performed to verify the optimized weld condition showed that the tensile strength of the weld joint was over 32kN, which is considerably higher than the required strength, i.e., 23kN.

Evaluation of Friction Spot Joining Weldability of Mg alloys (마찰교반 점용접(FSJ)을 이용한 Mg 합금의 접합성 평가)

  • Jo, Hyeon-Jin;Kim, Heung-Ju;Bang, Guk-Su;Cheon, Chang-Geun;Jang, Ung-Seong
    • Proceedings of the KWS Conference
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    • 2005.11a
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    • pp.183-185
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    • 2005
  • In an attempt to optimize friction spot joining process of Mg alloys, effects of joining parameters such as rotating speed, plunging depth, and dwelling time on the joints properties were evaluated. Experimental tests were carried out for lap joined AZ31B-H24 sheets. A wide range of joining conditions could be applied to join Mg alloys without defects in the weld zone except for certain welding conditions with an insufficient heat input. The microstructures and hardness variations in the weld regions are discussed. For sound joints without defects, tensile shear strength of weld joints was higher approximately 116% than typical tensile shear strength of electrical resistance spot-welded joints for magnesium(Welding handbook, Vol 3, AWS).

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Observation of Nugget Formation Mechanism by using High Speed Camera (고속카메라를 이용한 저항 점 용접의 너겟 형성 메커니즘 관찰)

  • 조용준;이세헌
    • Proceedings of the KWS Conference
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    • 2000.10a
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    • pp.43-45
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    • 2000
  • Resistance Spot Welding has been one of the important process in the sheet metal fabrication of auto-body industry It is well known that the nugget formation of RSW is the major factor for the strength of the body. A high speed camera was used to consider initial melting and growth of the weld nugget in order to find out the nugget formation mechanism. It was observed that such mechanism had an effect on the dynamic resistance, which was a process parameter of resistance spot welding. Also, the relationship between the mechanism and process parameter was considered for the industrial application.

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