本文選題：交織結構 + 沉積單道��； 參考：《南京理工大學》2017年碩士論文

【摘要】：電弧增材制造以電弧為熱源,焊絲為增添材料,快速直接成形致密度高、力學性能好的復雜結構件,具有生產(chǎn)周期短、高利用率、高效率等特點。本課題基于雙絲PMIG焊接機器人,以高氮鋼與316L不銹鋼為研究對象,對增材工藝成形特性及宏觀幾何尺寸的控制進行分析,開展多道重疊堆積試驗和增材工藝參數(shù)篩選,進行電弧增材成形異材交織結構的工藝研究。首先針對兩種材料分別開展沉積單道成形特性工藝研究,確定了兩種材料的增材工藝參數(shù)窗口,并探索了增材工藝參數(shù)對沉積單道宏觀幾何尺寸的影響規(guī)律。對于高氮鋼沉積單道的幾何尺寸,沉積速度對于寬度的影響大于送絲速度;沉積速度對于高度的影響略大于送絲速度。對于316L不銹鋼沉積單道的幾何尺寸,送絲速度對于寬度的影響遠遠大于沉積速度;沉積速度對于高度的影響大于送絲速度。接著進行了多道重疊堆積試驗以及增材工藝參數(shù)篩選。分析高氮鋼多道重疊堆積出現(xiàn)的缺陷,進一步縮小高氮鋼增材工藝參數(shù)范圍,隨后對異材沉積單道幾何尺寸、截面面積匹配總誤差值進行分析,從而得到最適合用于增材成形異材交織結構的工藝參數(shù),異材重疊堆積最佳道間距d1*=4.3mm,同材重疊堆積最佳道間距分別為d2*=4.2mm,d3*=4.4mm。然后對四種增材成形結構進行微觀組織和力學性能分析。異材界面中高氮鋼以柱狀晶形態(tài)沿熱流方向生長,316L不銹鋼以樹枝晶生長;重熔區(qū)的組織兩次受熱作用,兩次改變生長方向。交織結構異材界面處,316L不銹鋼硬度值變大,高氮鋼硬度值變小。交織結構保持較高抗拉強度,延伸率大幅增長,塑性變形能力提高。對于交織結構,沖擊兩種材料的先后順序造成吸收沖擊功的能力不一樣;交織結構內(nèi)部材料分布不同、成分比例相同,側面吸收沖擊功的能力相近;軟硬交織復雜部位正面、側面沖擊功相近,抗沖擊能力最強。最后建立典型交織結構三維模型,設計分割層的材料成分比例,提出封閉行走路徑減少起弧熄弧次數(shù),提高交織結構局部和整體的成形精度,減少需要后處理加工浪費的材料,增材成形典型交織結構件達到具體幾何尺寸要求。
[Abstract]:Arc as heat source, welding wire as additional material, rapid direct forming of high density, good mechanical properties of complex structural parts, with short production cycle, high utilization rate, high efficiency and so on. Based on the dual-wire PMIG welding robot, the forming characteristics and macroscopic geometric size control of the material increasing process are analyzed, and the multi-channel stacking test and the screening of the material increasing process parameters are carried out, taking the high-nitrogen steel and 316L stainless steel as the research object. The process of forming interlaced structure of different materials by arc augmentation was studied. Firstly, two kinds of materials were studied on the characteristics of deposition single pass forming, and the window of material increasing process parameters was determined, and the influence of material increasing process parameters on the macroscopical size of deposition single channel was explored. The effect of deposition velocity on width is greater than that on wire feeding speed, and deposition velocity on height is slightly greater than wire feeding speed for the geometric dimension of single channel deposition of high nitrogen steel. For the geometry size of single channel deposited in 316L stainless steel, the influence of wire feeding velocity on width is much greater than deposition velocity, and deposition velocity on height is greater than wire feeding speed. Then the multi-channel stacking test and the screening of material-increasing process parameters were carried out. The defects of multi-channel overlapping stacking of high-nitrogen steel are analyzed, and the range of processing parameters of high-nitrogen steel is further reduced. Then, the geometric size of single channel and the total error of cross-section area matching are analyzed. Thus, the most suitable process parameters for forming interleaving structure of different materials are obtained. The optimum channel spacing of different material stacking is 4.3mm, and the optimum spacing of overlapping stacking is 4.2mm / d ~ (3) mm / d ~ (4) mm, respectively. Then, the microstructure and mechanical properties of four kinds of forming structures were analyzed. In the interface of different materials, the high nitrogen steel grows in columnar crystal form along the direction of heat flux, and the microstructure of the remelting zone is heated twice and the growth direction is changed twice. The hardness value of 316L stainless steel and high nitrogen steel become larger and smaller at interleaved interface. The interwoven structure maintains high tensile strength, and the elongation increases greatly, and the plastic deformation ability is improved. For interwoven structures, the sequence of impact materials causes the difference in the ability to absorb impact work; the internal distribution of materials in the interwoven structure is different, the proportion of components is the same, and the ability to absorb impact work on the side is similar; the front of the soft and hard interwoven complex parts is similar. The side impact work is similar, and the impact resistance is the strongest. Finally, a three-dimensional model of typical interleaved structure is established, and the proportion of material components in the dividing layer is designed. The closed walking path is proposed to reduce the number of arc extinguishing, to improve the forming accuracy of the local and whole interleaving structure, and to reduce the material waste in post-processing. The typical interlaced parts of material forming meet the requirements of specific geometric dimensions.
【學位授予單位】：南京理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG142.71;TG661

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