Ispitivane su greške u zavarenom spoju niskougljičnog čelika S235JR debljine 6 mm zavarenog MAG postupkom. Uzorak koji sadrži greške naljepljivanja i pore je ispitivan kompjutorskom tomografijom - ...KT. Programskom analizom tomografa je određena veličina i pozicija grešaka naljepljivanja kao i dimenzije i raspored pratećih pora u zavarenom spoju.
Dynamic Process of MAG Welding Robot Shengmian Xie; Shisheng Huang
2010 International Conference on Measuring Technology and Mechatronics Automation,
2010-March, Volume:
2
Conference Proceeding
Based on detailed analysis of the dynamic relations between variables which affect the stability of MAG welding robot system each other, the dynamic model of the system is established. Sequentially, ...based on this model, stability simulation, disturbance resistance simulation, dynamic regulation and analysis of system amelioration are put up.
During the last years, globalization and the necessity to reduce production costs have pushed industry to employ more and more manufacturing robotized cells. This trend has been assimilated by arc ...welding too. The use of robotic systems allows to increase the performance of productive systems by means of reduction in lead-time, reproducibility of processes and increase in quality. However, process automation needs pre-scheduling of manufacturing cell movements and also a setup of different welding parameters, such as power provided by the welding generator, arc length and robot speed, all of which allows to get a joint without defects. An online scheduling of robotic systems brings certainly a delay in production times, whereas offline scheduling allows to maintain the desired production without any production stop. An interface that allows to easily translate the coordinate points established by a simulation software (such as Robcad) in some complete programs that can be sent to the controller of the manufacturing cell, has been developed. Besides, in order to improve the joint’s quality, an analysis of the joint quality has been carried out by macrographic analysis. The employment of image analysis techniques on the obtained macrographs allowed to translate the morphology of each joint in terms of a matrix. After different morphologies have been distinguished in numerical terms and correlated to the joint’s quality, these data have been introduced as input to the interface. The output, constituted by the program for the controller of the cell and the best welding parameters, under such conditions, has allowed to increase both the cell’s productivity and the quality of the joints. Therefore, during offline scheduling, the initial phase of loop control of the joint morphology allows to evaluate the best welding parameters both in terms of productivity and joint quality. The same interface allows also to plan the best parameters for different welded joints with varying thickness and typology, which makes the system more eflexible and maintains a high level of productivity.
The whole system has been implemented on a robotized cell GMAW Gas Metal Arc Welding Comau, that foresees a welding robot with six degrees of freedom and a position system with other six freedom degrees. Different T fillet joints have been realized at using of weathering steel sheets 5 and 6 mm thick.
The change in arc sound with burn through in MAG welding was measured, being related with the welding current. Also, we observed the change in arc morphology with the burn through by a CCD camera. ...The welding current was 300 A and the welding speed was 5 mm/s, that is, the welding was carried out only in the spray transfer region. We made holes in the workpiece with diameters of 4-9 mm in advance of welding and intentionally produced the burn through. Two types of burn through were observed. One of them was the stagnation type in which molten metal temporally stands on the hole before the burn through. In the other, the molten metal does not stagnate. In the stagnation type, the arc sound instantly becomes low immediately before the burn through and increases suddenly at the same time when the burn through occurs.
Blowholes on Pulsed MAG Welding Yamada, Tadaaki; Kobayashi, Minoru
QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY,
1985, Volume:
3, Issue:
4
Journal Article
Open access
Blowholes and their formation of Pulsed MAG welding was investigated. Among welding parameters such as arc length, average current, wire extension, welding speed and shielding gases, arc length was ...the most important factor. The average size of blowholes was as small as 0.62 mm. As results of analysing gas components of the blowholes by means of gas chromatograph, Ar, H2, and CH4 were detected and CO2 and CO and O2 were not in the blowholes. H2 and CH4 were also detected in blank test pieces. From SEM observation, the shape of the blowhole was like a sphere, the bottom of which was flat and the upper side was uneven like a corn having a slag spot at the top. The slag composition in the blowhole was Al, Si, Mn, Ca, La and Ce etc., and differed from the slag on the weld bead. From these results, the mechanism of blowhole formation in Pulsed MAG welding was considered as follows. Disturbance of the weld pool accompanied with spattering forms gas bubbles of the shielding gas in the pool. Small bubbles tend to be dragged into the bottom of the pool by whirling action, and be confirmed there to form blowholes close to the fusion line. CO2 in the blowholes are deoxidized to form the slag at the top of the blowholes.
Compared to conventional MIG welding, the MIG welding with filler wire, where a filler wire is fed into MIG welding arc, improves efficiency by minimizing the heat input and increasing the deposition ...rate. However, discussion arises on controlling the convex bead which arises at increased deposition rate. In this study, it is attempted to control the uneven bead in the MIG welding with filler wire by applying magnetic control of the arc. Furthermore, possibility of controlling the weld metal content is investigated which is favourable for cladding by welding of dissimilar metal i.e. clad steel, corrosion and heat resistant alloys and so on. The diameter of the filler wire was 1.2 mm, the electric current for the welding was 180-350A, the magnetic field for oscillating the arc was 0.004-0.006T and 5Hz. Experimental results showed that the bead of excellent appearance was obtained and it could be flattened by applying magnetic field even at increased deposition rate of MIG welding with filler wire. The penetration was found to be approximately 50% of conventional MIG welding. It was also found possible to control the amount of Ni and Cr, which are important elements for corrosion and heat resistant alloys, and to deviate for them to the bead surface by varying composition and feed rate of the electrode wire and the filler wire. It is said from these findings that this welding method is suitable for cladding by welding to improve efficiency and quality.
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