發(fā)布時(shí)間：2018-05-15 22:15

  本文選題：激光熔覆 + 薄壁件��； 參考：《新疆大學(xué)》2017年碩士論文

【摘要】：英國《經(jīng)濟(jì)學(xué)人》雜志認(rèn)為增材制造技術(shù)將與其他數(shù)字化技術(shù)一起推動(dòng)第三次工業(yè)革命。激光熔覆成形能夠制造全致密金屬零件的增材制造工藝。采用激光熔覆技術(shù)成形薄壁件,可以得到組織致密和性能優(yōu)良的薄壁件。使用激光熔覆3D打印及再制造系統(tǒng)進(jìn)行熔覆成形實(shí)驗(yàn)研究,采用搭建水冷實(shí)驗(yàn)工作臺(tái)進(jìn)行實(shí)驗(yàn)。單道熔覆成形是薄壁件成形的基礎(chǔ)。激光熔覆單道熔覆軌跡的高度和寬度、熔池深度主要取決于激光功率、送粉速率、掃描速度等熔覆工藝參數(shù),研究得到單道熔覆軌跡幾何尺寸和激光熔覆過程中激光功率、送粉速率和掃描速度之間的關(guān)系。通過正交實(shí)驗(yàn)分析工藝參數(shù)對(duì)熔覆層寬度和高度的影響程度大小,并建立回歸方程。本文成形的薄壁件為激光熔覆單道多層成形。激光熔覆成形的薄壁件零件是單道熔覆軌跡逐層堆積起來形成的,通過實(shí)驗(yàn)選擇合理的工藝參數(shù)和路徑,由層高控制成形過程中Z軸提升量,成形直薄壁件和曲面薄壁件,解決了成形中粘粉、坍塌、“起點(diǎn)高”“尾縮”和裂紋現(xiàn)象,得到表面良好的薄壁件。研究曲率不同的圓弧成形的薄壁件高度,曲率小的高度較穩(wěn)定,曲率大的高度變化明顯;成形薄壁件表面質(zhì)量的測定實(shí)驗(yàn),并進(jìn)行方差分析,送粉速率對(duì)表面質(zhì)量影響最大。成形薄壁件的金相組織良好,激光熔覆成形的薄壁件試樣拉伸強(qiáng)度為573.7MPa,優(yōu)于不銹鋼熱軋鋼板的拉伸強(qiáng)度。對(duì)單道熔覆溫度進(jìn)行實(shí)驗(yàn),研究得到基板溫度變化與工藝參數(shù)之間的關(guān)系。采用熱電偶和熱成像儀兩種方式測得薄壁件成形過程中溫度變化,并擬合比較溫度曲線,熱成像儀所測溫度偏低。金屬熔覆成形過程中,是多場耦合的復(fù)雜過程,將溫度場的數(shù)值模擬和溫度場實(shí)驗(yàn)相結(jié)合,能夠更加直觀、全面地研究溫度場的變化過程。通過溫度場數(shù)值模擬的方法對(duì)單道熔覆成形和薄壁件過程中溫度場進(jìn)行模擬并與實(shí)驗(yàn)對(duì)比,對(duì)比擬合數(shù)據(jù)基本符合,采用相同模擬參數(shù)對(duì)薄壁件成形進(jìn)行模擬,研究得到成形中溫度累積效應(yīng)和變化規(guī)律。
[Abstract]:The Economist believes that the technology will drive the third industrial revolution along with other digital technologies. Laser cladding can be used to fabricate all dense metal parts. Thin-walled parts with compact structure and excellent properties can be obtained by laser cladding technology. The laser cladding 3D printing and remanufacturing system was used to study the cladding forming experiment, and the water cooling experiment bench was built. Single-pass cladding is the foundation of thin-wall forming. The height and width of the laser cladding path and the depth of the melting pool are mainly determined by laser power, powder feeding rate, scanning speed and other technological parameters. The geometric dimension of the single channel cladding trajectory and laser power during laser cladding are studied. The relationship between powder feeding rate and scanning speed. The influence of process parameters on the width and height of cladding was analyzed by orthogonal experiment, and the regression equation was established. The thin-walled part formed in this paper is laser cladding single-pass multi-layer forming. The thin-walled parts formed by laser cladding are stacked up layer by layer with single-pass cladding track. Through experiments, reasonable technological parameters and paths are selected, Z axis lifting amount is controlled by layer height, and straight thin-walled parts and curved thin-walled parts are formed. The phenomena of sticking powder, collapsing, "starting point height", "tail shrinkage" and crack are solved, and the thin wall parts with good surface are obtained. The paper studies the height of thin-walled parts with different curvature, the height of small curvature is stable, the height of big curvature changes obviously, and the measurement of surface quality of thin-walled parts is carried out, and the analysis of variance shows that the powder feeding rate has the greatest influence on the surface quality. The tensile strength of the thin wall formed by laser cladding is 573.7 MPa, which is better than that of the hot rolled stainless steel plate. The relationship between substrate temperature and process parameters was studied by experiments on single pass cladding temperature. The temperature change of thin-walled parts during forming was measured by thermocouple and thermal imager, and the temperature curve was fitted and compared. The temperature measured by thermal imager was lower than that measured by thermocouple. The process of metal cladding forming is a complex process of multi-field coupling. Combining the numerical simulation of temperature field with the experiment of temperature field, the process of temperature field change can be studied more intuitively and comprehensively. The temperature field in the process of single-pass cladding forming and thin-wall forming is simulated by numerical simulation of temperature field and compared with the experiment. The comparison and fitting data are basically consistent, and the same simulation parameters are used to simulate the thin-walled forming. The cumulative effect and variation law of temperature are obtained.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG665

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