發(fā)布時間：2018-04-06 02:37

  本文選題：氣動噴丸清理　切入點：噴嘴結(jié)構(gòu)　出處：《重慶理工大學》2017年碩士論文

【摘要】：氣動噴丸清理因其成本低、效率高、質(zhì)量好等諸多優(yōu)點,廣泛地應用于航天航空、汽車、機械、化工、石油、船舶等行業(yè),在材料保護和表面工程中發(fā)揮著重要作用。然而,現(xiàn)在工業(yè)噴丸清理技術(shù)缺乏深入地效率分析和噴嘴結(jié)構(gòu)優(yōu)化,工藝參數(shù)選取主要憑經(jīng)驗,隨意性大,缺乏理論指導和試驗優(yōu)化。本文采用CFD的方法研究噴嘴流場分布特性及壁面的沖蝕特點,通過清理試驗優(yōu)化噴丸清理工藝參數(shù),為氣動噴丸噴嘴結(jié)構(gòu)設(shè)計和噴丸工藝參數(shù)的選擇提供了理論依據(jù)。首先,應用Fluent軟件,采用Standard k~ε模型對不同類型噴嘴進行氣固兩相流場模擬仿真,深入研究收縮型、文丘里型和流線型噴嘴內(nèi)流場及外流場的流場特性,獲得了射流壓力、速度以及磨料發(fā)散分布的規(guī)律。研究表明,文丘里型噴嘴發(fā)散性較好,加工成本低。綜合考慮,選用文丘里型噴嘴進行噴丸清理性價比較高。其次,通過改變噴嘴的結(jié)構(gòu)參數(shù),對文丘里型噴嘴進行氣固兩相流場模擬仿真,獲得了不同參數(shù)下氣體和顆粒的速度場及顆粒的運動軌跡。分析比較得出:收縮角α=30°,擴散角β=7°,噴嘴出口直徑與通徑之比為1.7左右的文丘里型噴嘴清理效果較好,進而優(yōu)化了噴嘴結(jié)構(gòu)。然后,利用優(yōu)化后的文丘里型噴嘴對壁面進行氣固兩相沖擊流場的仿真研究,得出了不同噴射壓力和噴射距離的氣體對流場加速的影響,以及不同噴丸工藝參數(shù)對垂直壁面沖蝕的影響。研究表明:壁面離噴嘴出口距離在小于100mm,磨料直徑為0.5mm左右,平均沖蝕率較好,噴丸清理效率較高。最后,對噴漆鋼板進行噴丸清理試驗,通過比較噴射壓力、噴射距離、噴射時間和噴射角度對試樣的表面清潔度和粗糙度影響,獲得了最佳的工藝參數(shù)值。通過對不同磨料和污垢鑄件噴丸清理,清理效果的對比分析表明,陶瓷丸的清理效果優(yōu)于玻璃珠、白剛玉的清理效果,噴丸清理對有機物污垢或覆蓋性污垢適應性強,表面損傷較小。
[Abstract]:Pneumatic shot peening is widely used in aerospace, automobile, machinery, chemical industry, petroleum, ship and other industries because of its low cost, high efficiency, good quality and so on. It plays an important role in material protection and surface engineering.However, the industrial shot peening cleaning technology is lack of in-depth efficiency analysis and nozzle structure optimization, the selection of process parameters is mainly based on experience, randomness, lack of theoretical guidance and test optimization.In this paper, CFD method is used to study the characteristics of nozzle flow field distribution and wall erosion. Through cleaning test, the parameters of shot peening cleaning are optimized, which provides a theoretical basis for the structure design of pneumatic shot peening nozzle and the selection of shot peening process parameters.Firstly, using Fluent software and Standard k- 蔚 model to simulate gas-solid two-phase flow field of different types of nozzles, the characteristics of flow field and flow field of condensed, Venturi and streamline nozzles are studied in depth, and the jet pressure is obtained.Velocity and distribution of abrasive divergence.The results show that Venturi nozzle has good divergence and low processing cost.Considering synthetically, the Venturi nozzle is selected for shot-peening cleaning with high cost-effective ratio.Secondly, by changing the structure parameters of the nozzle, the gas-solid two-phase flow field of Venturi nozzle is simulated, and the velocity field and particle motion track of gas and particle are obtained under different parameters.Analysis and comparison show that the Venturi nozzle with contraction angle of 30 擄, diffusion angle of 7 擄and the ratio of nozzle diameter to path diameter of 1.7 is better, and the nozzle structure is optimized.Then, by using the optimized Venturi nozzle to simulate the gas-solid two-phase impingement flow field on the wall, the effect of different injection pressure and injection distance on the acceleration of the gas flow field is obtained.And the effect of different parameters of shot peening on the erosion of vertical wall.The results show that the distance between the wall and nozzle outlet is less than 100mm, the abrasive diameter is about 0.5mm, the average erosion rate is better, and the efficiency of shot peening is higher.Finally, a shot peening cleaning test was carried out on the painted steel plate. By comparing the effects of spray pressure, injection distance, injection time and injection angle on the surface cleanliness and roughness of the sample, the optimum technological parameters were obtained.The comparative analysis of shot peening effect of different abrasive and fouling castings shows that the cleaning effect of ceramic pellets is better than that of glass beads, white corundum, and shot peening has a strong adaptability to organic dirt or overlay fouling, and the cleaning effect of ceramic pellets is better than that of glass beads, white corundum and shot peening.Surface damage is small.
【學位授予單位】：重慶理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG668

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本文編號：1717622