• Journal of Welding and Joining
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• 제13권4호
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• pp.122-131
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• 1995

An automatic welding equipment for thick plates requires the capability of the seam tracking of the weld line which often includes misalignment of the workpiece and variation of groove width. In this study, an automatic welding equipment and control algorithms based on the arc sensor were proposed for the GMA welding of thick plates which had misalignment and gap variation. The developed system being constituted with 5 axis can be automatically controlled by computer and also automnatically set the welding conditions such as welding current, and voltage. The proposed algorithms for the seam tracking in multi-pass welding of the thick plates were constituted as follows : the detection of weaving-end point for findng the variation of groove width, the control of welding velocity for acquiring a constant thickness deposition of weld metal, and the calculation of groove width and height of an arbitrary pass in the multi-pass weld. As results of the application of the system, it was revealed that the system had a good capability in seam tracking and made an excellent weld quality in V groove butt joint.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.448-451
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• 1986

An automatic welding system is designed for a part of fork lift. The system is composed of articulated type welding robot, welding positioners, shuttle for robot, system controller and welding equipment. From the application of the system, stable weld quality and production cost saving are achieved. In this paper, the hardware features and control structure of the system are presented.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1998년도 특별강연 및 추계학술발표 개요집
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• pp.129-132
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• 1998

The dynamic resistance monitoring in primary circuit or T/C 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. It is well known that tile dynamic resistance curve gives us very useful information about nugget growth and weldability. In the present paper, a new dynamic resistance detecting method is presented as a practical manner of weld quality assurance using instantaneous current and voltage measured by primary circuit. Primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality assurance index and eventually feedback control will be possible caused by T/C based monitoring system.

• Journal of Welding and Joining
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• 제17권2호
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• pp.97-103
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• 1999

The dynamic resistance monitoring in primary circuit is one of the important issues. Because in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. In this study, new dynamic resistance detecting method is proposed as a practical manner of weld quality assurance using instantaneous current and voltage measured at the primary circuit. and also, various patterns of primary dynamic resistance curve are characterized with the macro photograph and the weldability lobe curve. It is found that the primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality information and eventually real time feedback control will be possible.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.331-333
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• 2005

It comes up conversation in automobile industry that some technologies related to production and quality for goods have to be developed to make rationalization of the unit cost of production because material of car muffler is replaced by expensive stainless steel having corrosion-resistance and oxidation-resistance. Quality evaluation and control is direct method for the company producing welded goods in large quantities to increase productivity and to improve quality. It seems that prevention of inferior quality and increasement of productivity will be hard if production design does not have quality evaluation method related to weld assembly, They have been producing welded goods using MIG weld but still do not have not only quality evaluation method but also evaluation criterion for welded joint. In this study, the way for development of quality evaluation method is showed by analysis and calculation of waveform to improve technology related to welding process

• Journal of Welding and Joining
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• 제25권6호
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• pp.64-70
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• 2007

Recently, several models to control weld quality, productivity and weld properties in arc welding process have been developed and applied. Also, the applied model to make effective use of the robotic GMA(Gas Metal Arc) welding process should be given a high degree of confidence in predicting the bead dimensions to accomplish the desired mechanical properties of the weldment. In this study, a development of the on-line learning neural network models that investigate interrelationships between welding parameters and bead width as well as apply for the on-line quality control system for the robotic GMA welding process has been carried out. The developed models showed an excellent predicted results comparing with the predicted ability using off-line learning neural network. Also, the system will extend to other welding process and the rule-based expert system which can be incorporated with integration of an optimized system for the robotic welding system.

• 한국정보통신학회논문지
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• 제9권6호
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• pp.1379-1386
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• 2005

현재 산업현장에서 활용하는 용접용 로봇은 대부분 오프라인(off-line)으로 작업을 수행하고 있어 생산성과 용접 품질 향상에 그 기능을 충분하게 발휘하지 못하는 실정이다. 현재에는 용접 품질 향상을 위하여 용접 매카니즘이 많이 연구되어 많은 수학적인 해석과 물리적인 해석방법을 도입하여 비선형적인 용접 메카니즘을 연구하고 있다. 이러한 여러 가지 비선형적인 문제와 해석상의 어려움에도 불구하고 용접의 결함을 보완하기 위해 보다 정확한 용접데이터를 생성하기 위하여 고감도의 센서를 도입하여 신호처리 하고 있으며, 이를 이용하여 용접시스템에 포함시키는 피드백제어시스템(feed-back control system)을 구성하여 용접선 추적 및 용접 비드(bead) 형상제어에 응용하고 있다. 또한, 최근에는 인공지능제어기술이 발달되어 인간의 학습능력과 의사결정능력을 대신하는 신경회로망(neural network)과 퍼지이론(fuzzy logic)을 도입하여 용접기술을 개발하고 발전시키고 있다. 본 연구에서는 신경회로망이론을 이용하여 실시간으로 용접시스템을 모니터링하고 퍼지제어기에 의하여 용접결함을 보정하는 지능시스템을 개발방법을 제시하고자 한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 추계학술발표 개요집
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• pp.208-211
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• 1995

Five cast gamma titanium aluminides, Ti-45~48%Al-2%Nb-2%Cr (nominal composition in at. %), were laser welded and their weld cracking susceptibilities were evaluated. Laser power, traversing rate and preheat temperature were systematically varied to generate a series of welds exhibiting a wide range of cooling rate ($100^{\circ}C/s-10,000^{\circ}C/s$). As Al content increased and the weld cooling rate decreased, solidification cracking susceptibility increased while solid-state cracking susceptibility decreased. Through laser beam energy input control and preheat, it was determined possible to produce high quality laser welds.

• Journal of Welding and Joining
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• 제10권3호
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• pp.1-12
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• 1992

A literature review was conducted to survey informations available on the welding metallurgy of aluminum alloys and its effect on fusion weldability, especially on solidification cracking and pore formation. Solidification cracking behavior of Al weld is a complicate matter as compared to other high alloys, where a relatively simple Fe-X(most detrimental elements S, P, B, Si, etc) binary diagram can be successfully applicable. Both additive and synergistic effects of elements should be considered together. A same element play a different role from system to system. Porosity, caused by hydrogen contamination of the weld is one of the most troublesome welding problems. The primary sources of hydrogen are believed to be an absorbed moisture on the filler metal or base metal and in the shielding gas. It is extremely important that reliable quality-control procedures be employed to eliminate all possible sources of hydrogen contamination. Selection of proper process and parameters is sometimes more important than controlling of alloying elements in order to make a defect-free weld.

• Journal of Welding and Joining
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• 제19권4호
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• pp.391-398
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• 2001

MIAB welding method uses a rotating arc as its heat source and is known to be efficient in pipe butt welding. The arc is rotated around the weld line by the electro-magnetic force resulting from the interaction of arc current and magnetic field. This paper is concerned with the experiment of initial stage for process control, monitoring for weld quality, and the design of coil system which is efficient of flux generation and concentration. A coil system for the generation of magnetic flux was designed and constructed. Magnetic flux density and arc rotating behavior are important factors in MIAB welding, so the relations between these factors and process parameters were investigated. Various experiments were performed for the steel pipes(48.1mm O.D and 2.0mm thickness). The magnetic flux density is increased by increasing exciting current and decreasing gap size. The maximum of arc rotating frequency is affected by exciting current and gap size. However, the variations of arc rotating frequency during welding and then the melting process are mainly influenced by welding current. Thus, it is considered that the results of this study can be used as important data on the monitoring for weld quality and the design of efficient coil system.