| The structure of metal sandwich board with hollow interlayer is composed of the upper /lower panels and the core board that is placed between two panels..Due to the existence of the hollow interlayer, the sandwich plate has low quality, high specific strength and specific stiffness. In addition, the sandwich plate has obvious advantages in such aspects as aseismic, heat insulation, shock compared with the traditional structure.Laser welding sandwich plate has made great achievements in recent years. But the main deficiency in the following two points: First, the connection between panel and core board is partial because of the high penetration of laser welding heat source; That is to say, there is a certain gap between the panel and core board, which affects the mechanical properties of sandwich plate. Second, the prominent advantage of laser welding in sheet, especially under 5 mm. But as the sheet thickness increases, the required power of laser welding enhances. So the expensive equipment is needed and thus limit production.This paper is aim at the high-efficient and high-quality manufacture of high strength steel sandwich plate and a new kind of plug welding is proposed. By using of the welding robot automatic welding and applying constraints MAG arc, the weld beads with good formation can be obtained. In addition, the tee joint welding of narrow clearance sheet can also be realized at a time. This paper mainly focuses on the coupled thermo-mechanical behavior of the plug welding process. The revised flux pieces arc heat source model is established. The feasibility of the heat source model is also verified by comparing with the actual topography. The welding temperature field and stress strain field of the tee joint are analyzed in numerical simulation by using finite element software ABAQUS. And by changing different constraint conditions, the deformation control of the welding method is investigated.The results of the paper are as follows: first, according to the influence of flux band,adhesive tape type, flux band height, welding current and voltage on the weld appearance, it can be indicated that the good weld form is obtained when the flux band,constrained by steel strip, is glued with a high temperature resistant adhesive tape; the height of flux band beyond panel is 2mm; the voltage is 20 V and the current is 200 A.Second, through the observation of welded joint microstructure, it can be seen that the coarse dendrite exists in the weld zone, which nucleates in the weld center and grows toward the direction of heat affected zone(HAZ). A number of lamellar microstructures existed in the HAZ. In addition, a large number of parallel linear precipitates are observed in grains. The hardness of welded joint is also tested. The average hardness ofHAZ is 185 HV, which is slightly higher than that of base material zone(175HV). The minimum hardness of weld zone is 150 HV. Third, due to the particularity of restricted arc, according to the simulation of temperature field in the sandwich plug welding and the experimental analysis of the characteristic point temperature, it found that the simulated temperature is close to the measured temperature. The point temperature(The distance to the weld center is equal) for core board is greater than that for panel. For this kind of welding method, core board may be burned through. So the forced forming with ceramic gasket is necessary. The rigid fixing of sandwich plates is realized by applying the coupling contract, namely reinforcement model. By comparing of the residual stress and deformation under the reinforcement model and non reinforced model in the path direction. It indicates that rigid fixing can effectively reduce the welding deformation.This has a reference value for the control of sandwich-plate welding deformation. |
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