本文選題：雙脈沖 + 電弧增材制造��； 參考：《南京理工大學(xué)》2017年碩士論文

【摘要】：雙脈沖電弧增材制造以雙脈沖電弧為熱源、絲材為增添材料,快速直接成型致密性、力學(xué)性能較好的金屬材料復(fù)雜幾何構(gòu)件,可極大提高材料的利用率、縮短產(chǎn)品的生產(chǎn)周期、降低生產(chǎn)成本,大幅提高生產(chǎn)效率和制造技術(shù)的核心競(jìng)爭(zhēng)力。本課題基于機(jī)器人雙脈沖電弧增材制造工藝技術(shù),以增材制造過(guò)程及工藝為研究對(duì)象,對(duì)Al-Mg高強(qiáng)鋁合金成型制造構(gòu)件的外觀形貌、關(guān)鍵尺寸、氣孔、顯微組織、機(jī)械性能開(kāi)展分析研究。首先就多層單道構(gòu)件進(jìn)行工藝試驗(yàn)研究,探究低頻頻率和電弧特性參數(shù)對(duì)多層單道直壁體組織及性能的影響及其規(guī)律。當(dāng)僅改變低頻頻率時(shí),發(fā)現(xiàn)雙脈沖電弧消除氣孔效果較直流脈沖電弧好,除根部氣孔外直壁體上端氣孔率低。多層單道截面組織主體由等軸晶組成,基體為α-Al,晶界處密集分布中間相Alo.56Mg0.44,分布形態(tài)呈網(wǎng)狀結(jié)構(gòu)。隨著低頻頻率從1Hz提高到9Hz,晶粒尺寸和延伸率先減小后增大,顯微硬度和抗拉強(qiáng)度先增大后減小,3Hz時(shí)取極值。水平拉伸試樣比垂直試樣的抗拉強(qiáng)度平均高了 8.4MPa,同時(shí),延伸率高了約5%。隨電弧特性參數(shù)的增大,電流電壓波形從矩形轉(zhuǎn)變?yōu)樘菪卧俎D(zhuǎn)變?yōu)槿切?且脈沖電流變化速率di/dt逐漸降低。隨著脈沖電流變化速率di/dt從高到低變化,多層單道直壁體側(cè)表面粗糙度降低,同時(shí)上表面的魚(yú)鱗紋越來(lái)越淺。平均晶粒尺寸和實(shí)際熱輸入趨勢(shì)呈W型變化趨勢(shì),平均顯微硬度和抗拉強(qiáng)度呈現(xiàn)的M型變化趨勢(shì),而垂直拉伸件的延伸率呈持續(xù)遞增趨勢(shì)。進(jìn)一步建立簡(jiǎn)易多層多道構(gòu)件算法模型,優(yōu)化改進(jìn)最優(yōu)焊道間距的算法,并對(duì)其進(jìn)行實(shí)體成型檢驗(yàn),實(shí)驗(yàn)結(jié)果和理論結(jié)果吻合度較高。同時(shí)對(duì)不同焊道間距的堆敷構(gòu)件內(nèi)部氣孔作分析比較,發(fā)現(xiàn)氣孔分布位置主要位于道間和層間的交界,以及焊道底部的中央位置,且當(dāng)焊道間距為最優(yōu)距離時(shí),氣孔相對(duì)最少。最后采用雙脈沖電弧增材制造的方法,建立三維幾何模型,并進(jìn)行路徑規(guī)劃和優(yōu)化軌跡,在線設(shè)計(jì)編寫(xiě)機(jī)器人程序并采用相對(duì)最佳的堆敷工藝參數(shù)自動(dòng)堆敷實(shí)體構(gòu)件,最后檢測(cè)成型尺寸,發(fā)現(xiàn)外壁的傾斜角度與理論值相比誤差率僅為1.7%,外倒錐體壁厚的離散系數(shù)為2.288%,內(nèi)十字筋壁厚的離散程度為1.898%,兩者壁厚均比較均勻,故用此系統(tǒng)通過(guò)參數(shù)優(yōu)化和路徑規(guī)劃可堆敷得到預(yù)期設(shè)計(jì)的高強(qiáng)鋁合金構(gòu)件。
[Abstract]:Using double pulse arc as heat source, wire as material, rapid and direct forming densification and good mechanical properties of complex geometric components of metal materials, the utilization rate of materials can be greatly improved and the production cycle of products can be shortened.Reduce production costs, significantly improve production efficiency and core competitiveness of manufacturing technology.In this paper, based on the technology of robot double pulse arc material augmentation, the appearance, key size, porosity and microstructure of Al-Mg high strength aluminum alloy forming components are studied.Mechanical properties are analyzed and studied.In this paper, the influence of low-frequency frequency and arc characteristic parameters on the structure and properties of multi-layer single-channel wall is studied.When the frequency of low frequency is changed only, it is found that the effect of double pulse arc is better than that of DC pulse arc, and the porosity at the upper end of straight wall is lower than that of DC pulse arc.The structure of the multilayer single channel section is composed of equiaxed crystals, the matrix is 偽 -Al.The mesophase Alo.56Mg0.44 is densely distributed at the grain boundary.With the increase of low frequency frequency from 1Hz to 9Hz, the grain size and elongation decrease first and then increase, and the microhardness and tensile strength increase first and then decrease to 3Hz.The tensile strength of the horizontal tensile specimen is 8.4 MPA higher than that of the vertical specimen, and the elongation of the horizontal tensile specimen is about 5% higher than that of the vertical specimen.With the increase of arc characteristic parameters, the waveform of current and voltage changes from rectangle to trapezoid and then to triangle, and the rate of variation of pulse current di/dt decreases gradually.With the change of pulse current rate (di/dt) from high to low, the surface roughness of multi-layer single straight wall decreases, and the scale grain of the upper surface becomes more and more shallow.The average grain size and the actual heat input trend are W-shaped, the average microhardness and tensile strength are M-shaped, while the elongation of vertical tensile parts is increasing continuously.A simple multi-layer multi-pass component algorithm model is further established to optimize and improve the optimal solder path spacing algorithm, and its solid forming test is carried out. The experimental results are in good agreement with the theoretical results.At the same time, it is found that the pore distribution is mainly located at the junction between the interpass and the interlayer, and the central position of the bottom of the welding pipe, and the porosity is the least when the distance is the best.Finally, using the method of double pulse arc material increasing manufacture, the 3D geometry model is set up, and the path planning and optimizing trajectory are carried out. The robot program is designed and written online, and the relative optimum stacking process parameters are adopted to automatically pile up the solid components.Finally, the shape size was detected. The error rate of the inclination angle of the outer wall was only 1.7 compared with the theoretical value, the dispersion coefficient of the wall thickness of the outer inverted cone was 2.288, the dispersion degree of the wall thickness of the inner cross reinforcement was 1.8988.The wall thickness of both sides was relatively uniform.Therefore, the expected design of high strength aluminum alloy members can be obtained by using this system through parameter optimization and path planning.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG661

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