本文選題：7075鋁合金 + 液態(tài)模鍛　； 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：鋁合金材料具有密度低、強(qiáng)度高的優(yōu)良特點(diǎn),在不同的熱處理下可以得到優(yōu)異的物理性能和機(jī)械性能,廣泛應(yīng)用于特種車輛零部件的加工制作。鋁合金液態(tài)模鍛成形方法具有產(chǎn)品質(zhì)量高、成本低、易管理的優(yōu)點(diǎn),其中金屬液的澆注過(guò)程是關(guān)鍵工藝環(huán)節(jié),傳統(tǒng)的澆注過(guò)程為手工澆注,存在著勞動(dòng)強(qiáng)度高、尺寸精度差等一系列問(wèn)題。本文以某特種車輛7075鋁合金端蓋成形為出發(fā)點(diǎn),設(shè)計(jì)改進(jìn)了金屬液定量輸料系統(tǒng),可實(shí)現(xiàn)在全封閉環(huán)境下定量輸送熔融金屬液,提高金屬液澆注精度,減少氧化缺陷,提高成形件質(zhì)量�；�2000KN通用液壓機(jī),設(shè)計(jì)加工了端蓋液態(tài)模鍛成形模具,在該模具上配合金屬液定量輸料裝置的澆注管道。選擇液態(tài)模鍛模擬軟件Pro CAST對(duì)金屬液充型過(guò)程進(jìn)行了模擬分析,優(yōu)化定量輸料系統(tǒng)的各工藝參數(shù),研究了不同充型速度下制件可能出現(xiàn)的缺陷狀況,模擬分析了沖頭水平運(yùn)動(dòng)速率等工藝參數(shù)對(duì)成形的影響規(guī)律,確定沖頭活塞運(yùn)動(dòng)速率為0.08m/s。設(shè)計(jì)了成形試驗(yàn)方案,研究了金屬液澆注溫度、模具預(yù)熱溫度和補(bǔ)縮量等工藝參數(shù)對(duì)成形件的微觀組織和力學(xué)性能的影響規(guī)律,確定最優(yōu)金屬液澆注溫度為720℃~730℃之間,最優(yōu)模具預(yù)熱溫度為200℃~250℃之間,確定最優(yōu)補(bǔ)縮量為3mm~4mm之間。對(duì)成形件質(zhì)量問(wèn)題進(jìn)行總結(jié),分別是冷隔和澆不足、表面缺陷和內(nèi)部縮松縮孔,通過(guò)提高保壓時(shí)間、控制金屬液溫度和模具溫度、改變模具潤(rùn)滑等方法加以解決。分析端蓋不同位置組織結(jié)構(gòu)和力學(xué)性能,法蘭處組織比較致密,晶粒分布均勻,性能最好;端蓋底部處容易出現(xiàn)縮松縮孔,力學(xué)性能相對(duì)較低;端蓋側(cè)壁易出現(xiàn)顯微裂紋,影響成形件的使用壽命。對(duì)拉伸試樣斷口形貌進(jìn)行觀察分析,斷口存在大量的韌窩和一定的微觀孔洞,部分位置分布著沿晶斷裂,總結(jié)斷裂機(jī)理主要為韌性斷裂,附帶一定程度的解理斷裂。
[Abstract]:Aluminum alloy has the advantages of low density and high strength. It can obtain excellent physical and mechanical properties under different heat treatment. It is widely used in the processing and manufacture of special vehicle parts. The liquid die forging method of aluminum alloy has the advantages of high product quality, low cost and easy management. The pouring process of molten metal is the key process, and the traditional casting process is manual casting, which has high labor intensity. A series of problems, such as poor dimensional accuracy, etc. Based on the forming of 7075 aluminum alloy end cover of a special vehicle, this paper designs and improves the quantitative feeding system of molten metal, which can realize the quantitative transportation of molten metal under the completely closed environment, improve the pouring precision of molten metal and reduce the oxidation defect. Improve the quality of forming parts. Based on 2000KN universal hydraulic press, the end cap liquid die forging forming die was designed and machined, and the pouring pipe of the liquid metal quantitative feeding device was used in the die. The liquid die forging simulation software Pro CAST was selected to simulate and analyze the filling process of liquid metal. The process parameters of the quantitative feeding system were optimized, and the possible defects of the parts at different filling speeds were studied. The influence of process parameters such as horizontal movement rate of punching head on the forming process is simulated and analyzed. The piston motion rate of punch head is determined to be 0.08 m / s. The forming test scheme was designed, and the influence of the process parameters such as pouring temperature of molten metal, preheating temperature of die and filling amount on the microstructure and mechanical properties of the forming parts was studied. The optimum pouring temperature of molten metal was found to be 720 鈩，

本文編號(hào)：1789578