韶钢宽板坯连铸机浸入式水口优化与改进

通过分析韶钢宽板坯连铸机浸入式水口在生产过程中出现的各种问题,改进浸入式水口的材质、尺寸结构,优化结晶器内钢水的流动状态和温度分布,规范水口烘烤,不仅提高水口使用寿命,减少了生产事故,还提高铸坯质量,取得了显著的效果。     

宽板坯连铸结晶器工艺参数优化的水模拟研究

结合国内某钢厂宽板坯连铸结晶器的4种断面宽度,建立1∶1水模型,并结合正交试验方法,研究了浸入式水口的吐出孔数、水口吹气量、水口浸入深度、拉速和结晶器断面宽度等不同因素对结晶器流场的影响,得到了4种宽板坯连铸结晶器的最佳工况条件。     

对一次连铸板坯漏钢的检验和分析

结晶器浸入式水口掉底,导致板坯产生表面纵向裂纹,最后发生漏钢事故.对连铸板坯漏钢的原因进行了分析.     

宽断面板坯结晶器内钢水流动、传热和凝固过程的数值模拟

建立了求解宽断面板坯结晶器内的钢液流动、传热和凝固数学模型,研究了不同浸入式水口结构、铸坯宽度、铸坯厚度和拉速等工况条件下,宽断面板坯结晶器内的流动、传热和凝固行为。结果表明：随着铸坯的宽度从1 800 mm增加2 200 mm时,从浸入式水口侧孔出来的射流在结晶器下部的影响范围更广;宽断面结晶器中的浸入式水口结构对不同铸坯断面和拉速下的流动和凝固行为产生较大的影响;在生产中需根据宽断面结晶器的流动及传热特点进行水口结构及工艺参数的优化。     

板坯连铸浸入式水口使用效果分析

本文通过对板坯连铸机不同材质和不同形状浸入式水口的使用情况,进行调查、分析,指出选择较好的材质及合理的水口形状,可提高连拉炉数,减少铸坯夹杂,改善铸坯质量。     

321不锈钢板坯夹杂物研究

用两步法冶炼321不锈钢,采用扫描电镜能谱分析方法,研究了连铸浸入式水口结瘤物和32l不锈钢连铸板坯表面夹杂物的成分,探讨了水口结瘤与表面夹杂物的关系。结果表明:板坯夹杂物主要包含Ti、O、N、Ca等元素,与浸入式水口结瘤物中包含的成分相同,说明连铸水口结瘤是造成32l不锈钢连铸板坯夹杂物的重要原因,并依此提出了防止浸入式水口结瘤的建议。     

不同宽度板坯结晶器浸入式水口优化的水模研究

采用1:2比例水模型进行物理模拟实验,研究了230mm×(1030,1270,1520,1650)mm宽度的板坯连铸结晶器的流场,优化浸入式水口结构。结果表明,在钢通量一定的情况下,随着结晶器断面宽度的不断增大,同一水口的流股冲击深度增大,整个液面活跃程度逐渐降低,导致液面偏死。可以通过改变水口的比面积,侧孔倾角,高宽比等水口结构参数来适应不同宽度的板坯结晶器连铸工艺要求。     

连铸工艺参数正交试验模拟优化

影响结晶器内流场的主要参数有浸入式水口倾角、水口的浸入深度、板坯尺寸,以及拉坯速度。运用模拟软件的模拟结果只能显示某个参数的影响规律,不能得到最佳的工艺参数组合。运用正交试验法对模拟结果进行优化,结果显示,该参数组合下的结晶器内流场十分稳定。有利于避免钢液卷渣现象的发生。     

国产薄板坯连铸用浸入式水口的开发与应用

介绍薄板坯连铸用浸入式水口的使用特点和FTSC浸入式水口的技术特点.进行国内薄板坯连铸用浸入式水口的研究与开发.通过在唐钢薄板坯连铸上应用,各方面性能满足薄板坯连铸的需要,达到了国外浸入式水口的水平.     

浸入式水口堵塞机理

本文分析了连铸浸入式水口堵塞的机理。浸入式水口堵塞现象可分为三步：夹杂物形成，夹杂物传递到水口壁，夹杂物粘附到水口壁上。分析了第一步对水口堵塞的影响。     

宽厚板坯连铸结晶器内的钢液流场的数值模拟

基于流体力学的基本理论,针对连铸结晶器的结构和工艺参数,利用商业软件fluent的k-ε湍流模型,实现了对结晶器内钢液流场的三维数学模拟。重点分析了浸入式水口的插入深度、水口侧孔倾角以及拉速等工艺参数对结晶器钢液流场的影响。结果表明：对于断面为2300mm×250mm的板坯结晶器,水口插入深度为150mm,水口倾角为向下15°,拉坯速度为1.2m/min时,结晶器内的流场较好。数值模拟结果可为宽厚板坯连铸结晶器确定合理工艺参数提供理论依据。     

Abrasive waterjet micro-machining of channels in metals: Comparison between machining in air and submerged in water

Abrasive water jet technology can be used for micro-milling using recently developed miniaturized nozzles. Abrasive water jet (AWJ) machining is often used with both the nozzle tip and workpiece submerged in water to reduce noise and contain debris. This paper compares the performance of submerged and unsubmerged abrasive water jet micro-milling of channels in 316L stainless steel and 6061-T6 aluminum at various nozzle angles and standoff distances. The effect of submergence on the diameter and effective footprint of AWJ erosion footprints was measured and compared. It was found that the centerline erosion rate decreased with channel depth due to the spreading of the jet as the effective standoff distance increased, and because of the growing effect of stagnation as the channel became deeper. The erosive jet spread over a larger effective footprint in air than in water, since particles on the jet periphery were slowed much more quickly in water due to increased drag. As a result, the width of a channel machined in air was wider than that in water. Moreover, it was observed that the instantaneous erosion rate decreased with channel depth, and that this decrease was a function only of the channel cross-sectional geometry, being independent of the type of metal, the jet angle, the standoff distance, and regardless of whether the jet was submerged or in air, in either the forward or backward directions. It is shown that submerged AWJM results in narrower features than those produced while machining in air, without a decrease in centerline etch rate.     

Performance and wear characteristics of ceramic, cemented carbide, and metal nozzles used in coal–water–slurry boilers

Ceramics, cemented carbides, and metals were prepared to be used as nozzles in CWS boilers. CWS burning tests in a boiler with these nozzles were carried out. The erosion wear resistance of these nozzles was compared by determining their erosion rates and hole diameter variation. Results showed that the life of the ceramic nozzles is about 30 times high than that of the metal nozzles. The wear types at the nozzle wall surface differed in various positions. The nozzle center wall section suffers form abrasive impact under low impact angles, and the damage at the center wall mainly occurs by plowing and plastic deformation for metals, and by polishing action for carbides and ceramics. The primary wear mechanisms at the exit of ceramic nozzle exhibited thermal shock damage with chipping owing to the greater thermal stresses.     

Fluid dynamic study of direct current plasma jets for plasma spraying applications

Recently, direct current (dc) plasma torches equipped with converging-diverging (Laval) nozzles, instead of standard cylindrical ones, have been shown to present several advantages for both vacuum and atmospheric plasma spraying, such as diminishing the gradients of temperature and velocity and reducing the turbulence intensity in the jet fringes. The present study was concerned with the diagnostics of the plasma jets produced by three nozzles of various contours: a standard cylindrical anode and a Mach 2.5 and Mach 3 Laval nozzle. Emission spectroscopy (absolute intensity) and enthalpy probe techniques were used to measure temperature and velocity fields. Special attention was given to the effects of spray chamber pressure on flow regime inside the nozzles and to the distribution of the temperature and velocity fields in the plasma jet. Results showed that under the chamber pressure conditions used (vacuum), for which Laval nozzles originally were designed, the generated plasma jets had greater centerline velocities and larger high temperature zones compared to standard cylindrical nozzles. The results showed significant improvement in the deposition efficiency by using nozzles with these computed contours.     

磨喷油嘴陶瓷结合剂CBN砂轮的研制及应用

本文对磨喷油嘴陶瓷结合剂CBN砂轮的制备及应用进行了研究,制定了适宜的陶瓷结合剂CBN砂轮的制备条件。所研制的陶瓷结合剂CBN砂轮磨削性能好,生产效率高,使用寿命长,加工工件质量高,能很好地满足喷油嘴的加工要求,且性能价格比优于普通砂轮和进口陶瓷结合剂CBN砂轮。     

高效埋弧焊技术的发展及应用

埋弧焊具有熔敷率高、焊接质量好等优点,是当今焊接生产中普遍使用的熔焊方法之一.介绍了多丝埋弧焊、带极埋弧焊、添加合金粉末埋弧焊、窄间隙埋弧焊、冷丝和热丝填丝埋弧焊等多种高效埋弧焊方法,并就各自的工艺特点、国内的应用情况进行了分析与总结.     

CeAlO3夹杂物在中间包覆盖剂的溶解行为

钢中存在的大量高熔点稀土夹杂物会在连铸过程中引发水口结瘤问题。通过静态法和热丝法高温原位观察研究了CeAlO₃夹杂物在中间包覆盖剂的溶解行为。静态试验研究结果表明,CeAlO₃在溶解过程中会产生中间层。随着溶解时间的增加,CeAlO₃溶解程度加剧,溶解形成的中间产物CaCeAl₃O₇逐渐长大。热丝法(SHTT)原位观察试验表明,CeAlO₃颗粒在溶解过程表观尺寸先降低后增加最后保持相对稳定。CeAlO₃在当前熔渣的溶解通过与渣中CaO反应形成产物层,然后形成的产物层向渣中溶解。因此,CeAlO₃在当前熔渣中的溶解方式为间接溶解。     

Wear mechanisms of gradient ceramic nozzles in abrasive air-jet machining

The nozzle is the most critical part in abrasive air-jet machining equipment. Ceramics, being with high wear resistance, have great potential as abrasive air-jet nozzle materials. In this paper, a (W,Ti)C/SiC gradient ceramic composite was developed to be used as nozzle material. The erosion wear behavior of the (W,Ti)C/SiC gradient nozzle was investigated and compared with a conventional ceramic nozzle. Results showed that the gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the conventional ceramic nozzles. The mechanism responsible was found to be that the tensile stresses at the entry region of the nozzle were greatly reduced when compared with the conventional nozzle. This effect may lead to an increase in resistance to fracture, and thus increase the erosion wear resistance of the gradient nozzle. It is indicated that gradient structures in ceramic nozzles are effective to improve the erosion wear resistance of conventional ceramic nozzles in abrasive air-jet machining.     

The features of cold spray nozzle design

This article presents the peculiarities of the supersonic nozzle design for the cold gas-dynamic spraying. The procedure to produce the high particle velocity by correct choice of the geometrical dimensions of the accelerating nozzles is described. Numerical and experimental research of wedge-shaped nozzles shows that there is a nozzle with its particular dimensions for a given type of particles that produces the maximum possible particle velocity at the moment of impact on a target surface.     

注射模整体式热流道系统

介绍了整体式热流道系统的发展和优势,分析了时间顺序控制针阀式喷嘴的无熔合缝注射,并给出了整体式热流道的结构和技术要点。