【摘要】：熔化極氣體保護焊是利用電弧作為熱源,氣體作為保護介質(zhì)的熔化焊,其中保護氣用量的成本約占焊接工藝成本的10%左右。因此,在保證焊接質(zhì)量基礎上,如何減小保護氣用量,對降低企業(yè)制造成本和節(jié)省資源具有重要的意義。本研究采用了理論分析、數(shù)值計算和實驗驗證的方法,對保護氣的用量進行了分析和探討,主要研究內(nèi)容如下:(1)根據(jù)氣體保護焊的相關理論,分析了焊接過程中影響保護氣用量參數(shù)之間的相關關系,提出了最小量保護氣的概念,構(gòu)建了保護氣最小量的數(shù)學模型。(2)依據(jù)保護氣最小量數(shù)學模型,設計出普通噴嘴、螺旋噴嘴、縮徑噴嘴和擴散噴嘴四種結(jié)構(gòu)的噴嘴,通過FLUENT軟件對四種噴嘴的保護氣流場進行分析計算。結(jié)果表明,相對于普通噴嘴,縮徑噴嘴和擴散噴嘴可以直接減少保護氣用量,而雙螺旋噴嘴通過增加熔池駐留時間來減少保護氣用量。(3)利用FLUENT軟件中的UDF和UDS模塊進行二次開發(fā),將電弧導入到流場中進行耦合仿真,結(jié)果表明電弧區(qū)的等離子保護氣的流場形態(tài)發(fā)生很大的變化,受到電弧影響位于工件表面的工件上保護氣體包裹效果更好,而在焊絲和工件表面之間出現(xiàn)保護氣縮徑現(xiàn)象。加載電弧的保護氣流場跟未加載電弧的流場進行比較,除了普通噴嘴外所得其余噴嘴各自最小氣體的用量結(jié)論基本一致。(4)構(gòu)建了焊接保護氣混合配比系統(tǒng),采用氬氣80%+二氧化碳20%混合保護氣,四種噴嘴、不同流量進行了焊接實驗。測試了樣件母材、熱影響區(qū)和焊接區(qū)的硬度,在熱影響區(qū)和母材區(qū)交界處,三種較小保護氣流量的焊縫的硬度要高于傳統(tǒng)大量的焊縫;通過觀察焊縫的金相組織,發(fā)現(xiàn)雙螺旋噴嘴的晶粒更加均與和細小。拉伸試驗時,樣件均在母材位置斷裂。總體結(jié)果表明,減小保護氣用量的焊縫能夠滿足甚至優(yōu)于普通大量保護氣焊縫的力學性能。本研究得到了江蘇省科技創(chuàng)新基金“船用高效氣體保護焊微量動態(tài)配氣系統(tǒng)”(BC2014202)的支持。本論文對氣體保護焊保護氣用量的研究和探討,對焊接領域的機理研究和工程應用具有一定的指導意義和參考價值。
[Abstract]:Arc is used as heat source and gas as protective medium. The cost of protective gas is about 10% of the cost of welding process. Therefore, on the basis of ensuring welding quality, how to reduce the amount of protective gas is of great significance to reduce the manufacturing cost and save resources. In this study, theoretical analysis, numerical calculation and experimental verification are used to analyze and discuss the amount of shielding gas. The main contents are as follows: (1) according to the related theory of gas shielded welding, In this paper, the correlation relationship between the parameters of protective gas dosage in welding process is analyzed, the concept of minimum protective gas is put forward, and the mathematical model of minimum amount of protective gas is constructed. (2) according to the mathematical model of minimum quantity of protective gas, the common nozzle is designed. The protected airflow field of four kinds of nozzles are analyzed and calculated by FLUENT software for spiral nozzles, diametral nozzles and diffusive nozzles. The results show that, compared with ordinary nozzles, diameter reduction nozzles and diffusion nozzles can directly reduce the amount of protective gas. The double helix nozzle reduces the amount of protective gas by increasing the residence time of the molten pool. (3) using the UDF and UDS modules in the FLUENT software for secondary development, the arc is imported into the flow field for coupling simulation. The results show that the flow pattern of the plasma shielded gas in the arc region changes greatly, and the shielding gas encapsulation effect is better on the workpiece which is affected by the arc, but there is the phenomenon of shielding gas shrinkage between the welding wire and the surface of the workpiece. Compared with the flow field of the unloaded arc, the results of the minimum gas consumption of the other nozzles except the ordinary nozzles are basically the same. (4) A welding protective gas mixing and matching system is constructed. The welding experiments were carried out with argon 80% carbon dioxide 20% mixed protective gas, four nozzles and different flow rates. The hardness of the base metal, heat affected zone and welding zone of the sample was tested. At the junction of the heat affected zone and the base metal area, the hardness of the weld with three kinds of smaller flux of protective gas was higher than that of the traditional mass weld, and the metallographic structure of the weld was observed. It is found that the grains of double helix nozzle are more uniform and fine. During the tensile test, the samples were broken at the base metal position. The overall results show that the welds with reduced amount of protective gas can meet or even outperform the mechanical properties of the conventional large amount of shielded gas welds. The research is supported by Jiangsu Provincial Science and Technology Innovation Fund, Marine High efficiency Gas shielded Welding Micro dynamic Valve Distribution system (BC2014202). This paper has some guiding significance and reference value for mechanism research and engineering application in welding field.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG444.72

【參考文獻】

相關期刊論文 前10條

1 彭小飛;馬國紅;張玉剛;平奇文;葉佳;;基于Fluent模擬TIG電弧燃燒[J];熱加工工藝;2016年01期

2 劉金祖;;Ar-CO_2混合氣體保護焊接技術(shù)應用特點解析[J];江西建材;2015年07期

3 路浩;陶傳琦;邢立偉;梁志敏;;鋁合金二元與三元氣體保護焊技術(shù)比較[J];焊接學報;2014年12期

4 賈時君;;焊接保護氣體的選擇[J];金屬加工(熱加工);2014年06期

5 張瑞華;李明;栗海霞;王榮;冷小冰;;等離子焊槍氣體保護效果數(shù)值模擬[J];電焊機;2012年04期

6 孫咸;;焊縫金屬的強度匹配方式及其應用[J];現(xiàn)代焊接;2012年01期

7 薛育強;史穎;李耀東;蘇斌;陳鵬;;Ar+CO_2混合氣體保護焊[J];焊接技術(shù);2011年07期

8 朱雙春;王寶森;馬朝暉;許軻;;新型螺旋噴出保護氣體的焊槍噴嘴設計[J];金屬加工(熱加工);2010年04期

9 王健;雷玉成;朱彬;;等離子焊接電弧流場數(shù)值分析[J];焊接;2008年02期

10 殷鳳良;胡繩蓀;高忠林;趙立志;;等離子體電弧數(shù)值模擬的研究進展[J];兵器材料科學與工程;2007年06期

相關碩士學位論文 前7條

1 胡翱;微型罩局部干法焊接風場結(jié)構(gòu)與電弧特性研究[D];南昌航空大學;2015年

2 柴彤彤;不同氣氛下焊接電弧的模擬研究[D];中北大學;2015年

3 李振團;S620Q高強厚板焊接過程數(shù)值模擬及實驗研究[D];內(nèi)蒙古科技大學;2015年

4 揣堯;非熔化極焊接電弧仿真研究[D];江蘇科技大學;2015年

5 王小偉;基于磁控技術(shù)MIG焊接熔滴行為的模擬研究[D];南昌航空大學;2013年

6 張通;動態(tài)焊接熱源模型的建立及數(shù)值模擬研究[D];河北工業(yè)大學;2013年

7 李海權(quán);Q235鋼閃光焊溫度場分析和焊接接頭性能研究[D];華南理工大學;2012年

，

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