数控火焰切割机切割质量控制研究

发布时间：2018-04-08 18:50

本文选题：数控火焰切割　切入点：切割面　出处：《武汉轻工大学》2016年硕士论文

【摘要】：数控火焰切割机因加工成本低,加工厚度大,广泛应用在船舶建造、矿山机械、海洋钻井平台、桥梁建筑与钢结构等行业。但在实际的切割加工中,钢板切割表面经常会出现边缘塌陷、表面粗糙、平面度差与形成裂纹等缺陷。本文针对上述情况,完成了如下方面的研究工作。1.针对各种气体火焰切割面质量缺陷,进行分类分析,探讨切割质量的相关影响因素及其产生的机理。2.基于电磁场对带电离子产生电场力及洛伦兹力的原理,采用实验室小试的方法,研究电场和磁场对火焰挺直度的影响。实验表明:合适的电场与磁场工作参数可以提升火焰挺直度,从而有效提升切割质量。当平行电极板相距46mm,电压为2000v,电场与平行方向偏转的角度接近90°时,火焰最长,且燃烧温度高;磁场强度为0.6T,N极与水平面呈45°角时,火焰高度基本无变化,燃烧温度提高。3.基于一维连续性方程,分析常规切割氧喷管出口速度低的问题。依据Laval喷管原理,设计了超音速割嘴。研究数据表明:该结构可有效提升切割氧挺直度、提升切割氧的速度、动量以及氧气纯度的保持能力,有助于提升切割质量。4.采用数值模拟的方法,运用流体模拟软件FLUENT对301-4型内混等压式割嘴流场进行了数值模拟与比对分析,得到了切割氧质量分数、速度及湍流动能在割嘴轴线上的变化等相关参数。结果显示:割嘴流场中切割氧纯度与速度在距离割嘴出口 75mm处大幅降低,此处切割氧纯度降低至95%,割嘴流场的温度与湍流动能在距离割嘴出口 75-125mm范围内急剧升高,这均表明3014型内混式等压割嘴的切割厚度极限为75mm,切割厚度在75mm以上钢板时,切割质量会变的特别差,甚至是不能切割。数值模拟的结果与割嘴实际技术参数基本吻合。5.对60mm的特厚钢板,采用青船科技制造的CFS-E10M数控火焰切割机,进行现场生产性试验,比较普通等压式割嘴与超音速割嘴的切割面质量。试验结果显示:采用超音速割嘴的表面平面度与粗糙度均优于普通等压式割嘴。
[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 掳, the flame has the longest flame and high combustion temperature, and when the magnetic field intensity is 45 掳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.
【学位授予单位】：武汉轻工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG48

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