【摘要】：針對中大直徑高強鋁合金螺柱焊接中存在的易燒損、未熔合、氣孔多、易氧化等技術問題,本論文以Φ18mm的5A06高強鋁合金螺柱為研究對象,以TIG-拉弧復合熱源螺柱焊接為基本焊接方法,開展了對螺柱焊接的保護裝置和保護形式及其復合工藝規(guī)范的設計研究。并根據(jù)螺柱接頭的力學性能、微觀組織形態(tài),對高強鋁合金螺柱焊接的復合工藝方法進行了綜合評估分析與優(yōu)化。本論文所設計的氣體保護裝置主要包含與螺柱焊槍配合的保護氣罩主體,與不同尺寸螺柱夾套配合的氣罩頂蓋,與陶瓷圈配合的氣罩底蓋。該保護裝置針對焊縫部位的惰性氣體氛圍設計了獨立氣室,有效降低了焊接過程中熔池部位的氧化,而且本裝置可以匹配不同直徑的螺柱,一套保護裝置即可適應全尺寸螺柱,解決了工程應用中氣體保護裝置適應性差的問題。本論文利用單因素法分析了各工藝參數(shù)對7A52鋁板焊縫成形的影響,確定了三個主要工藝參數(shù)的選擇范圍,利用正交試驗找到了最優(yōu)工藝參數(shù),并通過極差分析和方差分析對試驗結果進行了優(yōu)化,優(yōu)化后的接頭抗剪強度達到了176.4MPa,比正交結果最好的一組提高了5%,確定優(yōu)化后的工藝參數(shù)為最優(yōu)工藝規(guī)范,并以此為參考確定了5A06鋁板的最優(yōu)工藝規(guī)范,獲得了抗剪強度達184 MPa的螺柱接頭。在正交試驗優(yōu)化的工藝規(guī)范基礎之上,本論文研究了高強鋁合金螺柱焊接復合工藝方法,分析了混合惰性氣體及汽態(tài)釬劑對焊縫的保護作用,得出氦氣與氬氣按2：8配比的混合氣體與汽態(tài)釬劑保護復合工藝對高強鋁合金螺柱焊接保護效果更好,因為氦氣氛圍下的電弧能量更集中,對氧化膜與二次氧化的阻止更充分,增強了熔池的流動性,輔以汽態(tài)釬劑對熔池的主動清理作用,焊縫組織性能得到了極大改善,該復合工藝方法下的焊縫抗剪強度較純氬保護下的焊縫強度提高了10%以上。
[Abstract]:In order to solve the technical problems of high strength aluminum alloy stud welding with medium and large diameter, such as easy burning, non-fusion, large porosity and easy oxidation, this paper takes 桅 18mm 5A06 high strength aluminum alloy stud as the research object. Based on the welding method of TIG-arc composite heat source stud welding, the design and research of the protective device and protective form of stud welding and its composite process specification are carried out. According to the mechanical properties and microstructure of stud joint, the composite process of high strength aluminum alloy stud welding was evaluated and optimized. The gas protection device designed in this paper mainly consists of the main body of the gas shield matched with the stud welding gun, the top cover of the gas cover with different sizes of stud clamps, and the bottom cover of the gas cover with ceramic ring. The protective device designed an independent gas chamber for the inert gas atmosphere of the weld seam, effectively reducing the oxidation of the weld pool during the welding process, and the device can match the studs of different diameters, and a set of protective devices can adapt to the full-size studs. The problem of poor adaptability of gas protector in engineering application is solved. In this paper, single factor method is used to analyze the influence of process parameters on 7A52 aluminum sheet weld forming, and the selection range of three main process parameters is determined, and the optimum process parameters are found by orthogonal test. The test results were optimized by means of range analysis and variance analysis. The shear strength of the joints reached 176.4 MPa after optimization, which was 5 times higher than that of the best group of orthogonal results. The optimized process parameters were determined to be the optimal process specifications. The optimum process specification for 5A06 aluminum plate was determined and the stud joint with shear strength of 184MPa was obtained. On the basis of the optimized process specification of orthogonal test, the composite process of stud welding of high strength aluminum alloy was studied in this paper, and the protective effect of mixed inert gas and vapor flux on weld seam was analyzed. It is concluded that the composite process of helium and argon mixture gas and vapor flux protection at 2:8 is better for the welding protection of high strength aluminum alloy studs, because the arc energy is more concentrated in helium atmosphere. The resistance to oxide film and secondary oxidation is more adequate, the fluidity of the molten pool is enhanced, and the weld structure and properties are greatly improved by the active cleaning effect of the vapor flux on the weld pool. The shear strength of the weld is increased by more than 10% compared with that of the pure argon protection.
【學位授予單位】：南京理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG457.14

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本文編號：2134514