本文選題：數(shù)控火焰切割　切入點：切割面　出處：《武漢輕工大學(xué)》2016年碩士論文

【摘要】：數(shù)控火焰切割機因加工成本低,加工厚度大,廣泛應(yīng)用在船舶建造、礦山機械、海洋鉆井平臺、橋梁建筑與鋼結(jié)構(gòu)等行業(yè)。但在實際的切割加工中,鋼板切割表面經(jīng)常會出現(xiàn)邊緣塌陷、表面粗糙、平面度差與形成裂紋等缺陷。本文針對上述情況,完成了如下方面的研究工作。1.針對各種氣體火焰切割面質(zhì)量缺陷,進行分類分析,探討切割質(zhì)量的相關(guān)影響因素及其產(chǎn)生的機理。2.基于電磁場對帶電離子產(chǎn)生電場力及洛倫茲力的原理,采用實驗室小試的方法,研究電場和磁場對火焰挺直度的影響。實驗表明:合適的電場與磁場工作參數(shù)可以提升火焰挺直度,從而有效提升切割質(zhì)量。當平行電極板相距46mm,電壓為2000v,電場與平行方向偏轉(zhuǎn)的角度接近90°時,火焰最長,且燃燒溫度高;磁場強度為0.6T,N極與水平面呈45°角時,火焰高度基本無變化,燃燒溫度提高。3.基于一維連續(xù)性方程,分析常規(guī)切割氧噴管出口速度低的問題。依據(jù)Laval噴管原理,設(shè)計了超音速割嘴。研究數(shù)據(jù)表明:該結(jié)構(gòu)可有效提升切割氧挺直度、提升切割氧的速度、動量以及氧氣純度的保持能力,有助于提升切割質(zhì)量。4.采用數(shù)值模擬的方法,運用流體模擬軟件FLUENT對301-4型內(nèi)混等壓式割嘴流場進行了數(shù)值模擬與比對分析,得到了切割氧質(zhì)量分數(shù)、速度及湍流動能在割嘴軸線上的變化等相關(guān)參數(shù)。結(jié)果顯示:割嘴流場中切割氧純度與速度在距離割嘴出口 75mm處大幅降低,此處切割氧純度降低至95%,割嘴流場的溫度與湍流動能在距離割嘴出口 75-125mm范圍內(nèi)急劇升高,這均表明3014型內(nèi)混式等壓割嘴的切割厚度極限為75mm,切割厚度在75mm以上鋼板時,切割質(zhì)量會變的特別差,甚至是不能切割。數(shù)值模擬的結(jié)果與割嘴實際技術(shù)參數(shù)基本吻合。5.對60mm的特厚鋼板,采用青船科技制造的CFS-E10M數(shù)控火焰切割機,進行現(xiàn)場生產(chǎn)性試驗,比較普通等壓式割嘴與超音速割嘴的切割面質(zhì)量。試驗結(jié)果顯示:采用超音速割嘴的表面平面度與粗糙度均優(yōu)于普通等壓式割嘴。
[Abstract]:NC flame cutting machine is widely used in shipbuilding, mining machinery, offshore drilling platform, bridge construction and steel structure because of its low cost and large thickness.However, in the actual cutting process, the steel plate cutting surface will often appear edge collapse, surface roughness, planeness difference and crack formation and other defects.In view of the above situation, this paper has completed the following research work. 1.Aiming at the quality defects of various kinds of gas flame cutting surfaces, this paper analyzes the related factors of cutting quality and discusses the mechanism of cutting quality.Based on the principle of electric field force and Lorentz force produced by electromagnetic field on charged ion, the influence of electric field and magnetic field on flame straightness was studied by laboratory experiment.The experimental results show that proper working parameters of electric field and magnetic field can enhance flame straightness and thus improve cutting quality effectively.When the parallel electrode plate is 46mm apart, the voltage is 2000V, the angle between electric field and parallel direction is close to 90 擄, the flame has the longest flame and high combustion temperature, and when the magnetic field intensity is 45 擄between the pole and horizontal plane, the flame height is basically unchanged, and the combustion temperature is increased by .3.Based on one-dimensional continuity equation, the problem of low exit velocity of conventional cutting oxygen nozzle is analyzed.According to the principle of Laval nozzle, supersonic cutting nozzle is designed.The research results show that the structure can effectively improve the cutting oxygen straightness, the speed, momentum and the oxygen purity retention ability, and help to improve the cutting quality. 4.In this paper, the numerical simulation and comparison analysis of the flow field of 301-4 internal mixed constant pressure cutting nozzle are carried out by using the fluid simulation software FLUENT, and the relative parameters such as the mass fraction of cutting oxygen, the velocity and the turbulent kinetic energy on the cutting nozzle axis are obtained.The results show that the cutting oxygen purity and velocity in the cutting nozzle flow field decrease significantly at the distance from the mouth exit to the 75mm, where the cut oxygen purity decreases to 95. The temperature and turbulent kinetic energy of the cutting mouth flow field increase sharply in the range of 75-125mm distance from the mouth outlet.All of these indicate that the cutting thickness limit of the 3014 type internal mixed isobaric cutting nozzle is 75mm. When the cutting thickness is above 75mm steel plate, the cutting quality will be especially poor, or even can't be cut.The numerical simulation results are in good agreement with the actual technical parameters of the cutting nozzle.The experimental results show that the surface flatness and roughness of supersonic cutters are better than those of common isobaric cutters.
【學(xué)位授予單位】：武漢輕工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TG48

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