本文選題：數(shù)值模擬　切入點：多層多道焊　出處：《南京理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：重型車輛塔體由多塊20-60mm厚高強鋼板以及塔體頭拼焊而成,屬于典型的箱型結(jié)構(gòu),采用多層多道PMIG焊接工藝,依據(jù)工裝夾具定位固定,塔體制造要求嚴格的尺寸精度,需嚴格控制焊接變形。本文總結(jié)了前人對焊接數(shù)值模擬的研究,成功進行車體炮塔頂板和側(cè)板多層多道焊連接數(shù)值模擬,研究焊接過程中頂板的受熱變形規(guī)律以及不同焊道順序、不同約束條件下側(cè)板連接發(fā)生焊接變形的規(guī)律,并進行炮塔焊接工藝試驗,驗證焊接溫度、應(yīng)力場模擬計算結(jié)果。研究了塔體PMIG自動焊接熱源模型,對熱源雙橢球模型進行了二次開發(fā),通過校核熔融效果優(yōu)化熱源函數(shù)能量分布系數(shù)。頂板焊接開始后,熔池中心區(qū)域峰值溫度為2256℃,熔池呈“梨形”空間分布,隨著熱源前移,熔池溫度逐漸降低,等溫線輪廓呈現(xiàn)以焊接方向為長軸的近橢圓形狀,應(yīng)力應(yīng)變云圖顯示主要應(yīng)力分布區(qū)為起弧點、焊道中部和收弧點。研究了側(cè)板的焊接應(yīng)力場分布規(guī)律,研究三種焊道順序、三種約束條件下側(cè)板焊接的受熱及變形規(guī)律,Ⅲ方案焊道順序下板件受熱均勻,焊后變形量小,殘余應(yīng)力分布最優(yōu),焊縫體的最高應(yīng)力值為896.5MPa,起、收弧端應(yīng)力值在239～418MPa之間；綜合焊接變形和焊后殘余應(yīng)力分布,V方案約束條件最優(yōu),變形集中在焊縫上,焊縫體及近焊縫區(qū)的形變量在0.228～0.452mm之間,焊縫殘余應(yīng)力值在376.0～484.9MPa之間,殘余應(yīng)力的分布區(qū)域在夾具釋放后明顯縮小,應(yīng)力場分布得到優(yōu)化。進行了炮塔焊接工藝試驗：選測點的熱循環(huán)曲線變化趨勢與計算模型相一致,峰值溫度、溫度升高速度和溫度冷卻速度誤差百分比均符合精度要求；最終獲得的熔池形態(tài)中,第二道次的熔寬、熔深與模型中W2熔池區(qū)域基本一致；盲孔法測得1、2號特征點應(yīng)力值分別為169.4MPa、195.8MPa與模擬結(jié)果相近,板件的焊后變形趨勢與模擬結(jié)果相同。綜上所述,本文計算結(jié)果精度符合要求,模型驗證正確,本文的模型可以為焊接工藝方案制定提供參考。
[Abstract]:The tower body of heavy vehicle is composed of several thick steel plates of 20-60 mm thick and high strength, and the head of tower body is welded together. It belongs to the typical box type structure. It adopts multi-layer and multi-pass PMIG welding technology, and is fixed according to the fixture, and has strict dimensional precision required for the manufacture of tower body. It is necessary to strictly control welding deformation. In this paper, the previous researches on welding numerical simulation are summarized, and the numerical simulation of multi-layer and multi-pass welding connection of car body turret roof and side plate is successfully carried out. The rules of thermal deformation of roof in welding process and the rules of welding deformation of side plate connection under different welding pass sequence and different restraint conditions are studied. The welding process test of turret is carried out to verify the welding temperature. The heat source model of PMIG automatic welding of tower body was studied. The double ellipsoid model of heat source was redeveloped. The energy distribution coefficient of heat source function was optimized by checking the melting effect. The peak temperature in the central region of the molten pool is 2256 鈩，

本文編號：1625606