常规板坯连铸机引锭杆对中装置的优化改进与应用

本文针对传统常规板坯连铸机的引锭对中装置进行结构优化,将原有庞大的液压动力装置调整为简约的电动装置,并带有顶头精确地定位功能;设计了对中装置顶头快换装置,实现了电动快速更换顶头的功能。通过结构优化,该对中装置较原有的液压拨爪装置定位更精确,操作更简单,维护更方面。     

浅谈锥形穿孔机组的改进

简述了为提高锥形穿孔机工作效率而进行的两处改造方案,即改进导板装置和增加顶头更换装置,通过实践检验,这两处改进确实达到了预期的目的,取得了良好的效果。     

延长热轧穿孔顶头使用寿命的措施

针对国内钢管行业使用热轧穿孔顶头的状况,提出延长热轧顶头使用寿命的措施优化热轧顶头形状尺寸及冷却条件;优化热轧顶头热处理工艺;改进热轧顶头材料.     

延长热轧顶头使用寿命的措施

本文针对我国钢管行业使用热轧穿孔顶头的状况,提出延长热轧顶头使用寿命的措施:优化热轧顶头形状尺寸及冷却条件,优化热轧顶头热处理工艺,改进热轧顶头材料。起到了良好的效果。     

177mmPQF无缝钢管穿孔机顶头冷却环系统改进

对鞍钢股份有限公司无缝钢管厂无缝钢管穿孔机顶头冷却环系统存在的设计缺陷进行了分析,针对水嘴布置不合理、冷却水喷到毛管外部造成毛管外部氧化、喷到毛管内部破坏抗氧化剂作用等缺陷提出了改进方案,在冷却环前端安装了冷却水反冲洗装置,并对冷却环进行了改进,实施后取得了预期效果。     

顶推穿孔法

在现有二辊斜轧穿孔过程中,一般用气缸推入装置将管坯推入穿孔机。当管坯与轧辊接触后,推入装置便返回原始位置,管坯在轧辊中进一步前进则靠轧辊与管坯之间的摩擦来实现。应该指出,为保证穿孔过程顺利进行,这种推入方式的穿孔机必须具有克服顶头轴向阻力所需的顶头前压下量。众所周知,在穿孔时,顶头前压下量若超过导致管坯中心撕裂的压下量——临界压下量,则会恶化穿孔后毛管的内表面     

二辊斜轧穿孔顶头喷水试验

目前,国内二辊斜轧穿孔机采用的内水冷穿孔顶头(材质为3Cr2W8V)消耗高,我厂φ100穿孔机穿孔顶头,过去消耗指标一直在0.2只/t左右,最高1988年达0.253只/t,为此我们进行了改进顶头结构,提高穿孔顶头头部冷却效果的喷水穿孔试验,效果很好现介绍于后。 一、改进前穿孔顶头的主要失效形式 1、塌鼻     

不断提高热轧生产机械化程度

烟台钢管厂φ100毫米热轧机组投产后,对劳动强度大占用劳力多的主要工序进行了革新,不同程度地改善了劳动条件,节省了人力物力,提高了产品质量。轧管机球顶头更换装置学习兄弟单位先进经验,将轧管机锥式顶头改     

φ100mm热轧机组穿孔顶头的改进

介绍了安钢φ１００ｍｍ热轧机组孔顶头设计和试验的改进情况，最终选定２０ＣｒＮｉＳｉＳＷ内水冷锥式新型顶头，该种顶头使用寿命长，轧件质量高，显示出良好效果。     

穿孔机顶头设计的ActiveX Automation方法

介绍了穿孔机顶头设计方法的现状和ActiveX Automation技术, 利用VB6.0基于ActiveX Automation技术开发了穿孔机顶头专用设计计算程序,并调用AutoCAD给出了设计图形结果.是快速进行顶头设计的良好方法.     

悬挂挡渣塞在宣钢150t转炉生产中的应用

介绍了宣钢150 t转炉悬挂式挡渣装置的性能、主要参数、工作方式、事故处理,对比了挡渣球出钢挡渣和挡渣塞出钢挡渣的使用效果,最终确定了挡渣塞出钢挡渣工艺。生产实践表明,150 t转炉采用挡渣塞挡渣出钢,可有效控制出钢下渣量,减少钢水回磷,提高了钢水质量和合金收得率,实现了降本增效的目的。     

Application results of Al2O3 porous plug containing TiO2, Al2O3 and MgO as matrixes on an actual operation

Al₂O₃ porous plugs containing TiO₂, Al₂O₃ and MgO in the matrix were applied for 200-t ladle (improved porous plug). Although cracks occurred in longitudinal and transverse direction in the conventional porous plugs, no cracks were observed in the improved porous plug. Therefore, the latter was superior to the conventional one in thermal shock resistance. Wear rate was 9.0 mm/heat for improved plug and 9.8 mm/heat for the conventional one in average. The improved plug showed higher corrosion resistance than the conventional one. With the improved porous plug O₂ cleaning was only necessary after every two heats. This was due to the high penetration resistance.     

精炼钢包底吹透气砖不过气的分析与改进

通过对实际生产中精炼钢包底吹透气砖不过气事故案例进行跟踪取样分析,找出其产生的原因。分析认为狭缝式透气砖气道的堵塞、透气砖表面覆盖有较厚的冷钢、底吹系统的漏气、防漏机构气室不畅通等因素造成了精炼钢包底吹不成功。针对上述因素,采取了相应的改进措施,包括对狭缝参数的调整、透气砖材质的优化、安装预报警装置、吹氩管路的改进、防漏钢机构的调整、座砖和热修补料的优化以及规范操作等。结果表明,因透气砖气道堵塞的发生率降低了76.4%,因透气砖表面覆盖有较厚的冷钢而造成堵塞的发生率降低了55.4%,明显减少了防漏机构漏气和堵塞的事故,取得了良好的效果。     

转炉挡渣出钢的改进研究

对承钢150t转炉所用挡渣塞的密度和形貌进行了优化研究,使下渣量控制在40mm以内,并通过在出钢前加入一定量的混合炉渣改质剂,稠化炉渣,使挡渣效果进一步提高。     

Criteria for the Formation of Sediment Plugs in Alluvial Rivers

A sediment plug is defined as aggradation in a river that completely blocks the main channel. Information from documented cases of sediment plug development in alluvial rivers was used to develop criteria for plug formation and to identify the setup conditions for sites that are prone to plug formation. Site characteristics, processes, and associated parameters were evaluated based on a comprehensive literature review and evaluation of data. A plug formation theory was developed and tested using a unique sediment transport/movable bed numerical model that simulates the key processes considered to affect plug formation. The theory and model were calibrated and validated against field data, and then used to develop simplified criteria that can be used to predict plug formation. Findings from this study can be used to identify sites that may be prone to plug formation, and the criteria can be used to evaluate the potential for plug formation based upon field site conditions when data are not available to complete a more detailed study.     

Experimental hypoxemic hypoxia: changes in R2* of brain parenchyma accurately reflect the combined effects of changes in arterial and cerebral venous oxygen saturation

PURPOSE: The objective of this study was to develop and evaluate a pulsatile drug delivery system based on an impermeable capsule body filled with drug and an erodible plug placed in the opening of the capsule body. METHODS: The erodible plugs were either prepared by direct compression followed by placing the tablets in the capsule opening or by congealing a meltable plug material directly within the capsule opening. The disintegration/erosion properties of these plugs were determined and optimized for the final delivery system. In order to assure rapid drug release of the capsule content after erosion of the plug, various excipients (fillers, effervescent agents) and drugs with different solubilities were evaluated. The lag time prior to drug release and the subsequent drug release were investigated as function of capsule content, plug composition, plug preparation technique, plug hardness, weight, and thickness. RESULTS: The erosion time of the compressed plugs increased with increasing molecular weight of the hydrophilic polymer (e.g. hydroxypropyl methylcellulose, polyethylene oxide), decreasing filler (lactose) content and decreased with congealable lipidic plugs with increasing HLB-value and inclusion on surfactants. For complete and rapid release of the drug from the capsule body, effervescent agents had to be included in the capsule content. The drug delivery system showed typical pulsatile release profiles with a lag time followed by a rapid release phase. The lag time prior to the pulsatile drug release correlated well with the erosion properties of the plugs and, besides the composition of the plug, could be controlled by the thickness (weight) of the plug. CONCLUSIONS: A single-unit, capsular-shaped pulsatile drug delivery system was developed wherein the pulsatile release was controlled by the erosion properties of a compressed or congealed plug placed within the opening of the capsule opening.     

生产低碳钢管在穿孔顶头表面形成氧化膜的方法

在小型穿孔机组上生产热轧无缝钢管时,穿孔顶头会因塌鼻、黏钢、缺肉、开裂等四种原因失效。在高温弱氧化气氛下,通过生产少量低碳钢可以在穿孔顶头表面生成一层主要成分为FeO、Fe3O4的氧化薄膜。由于氧化膜具有低导热系数及在高温下软化的特性,因而可以起到隔热、润滑的作用,从而降低顶头表面温度,提高基体强度,并阻止热焊合。这将延缓黏钢、缺肉失效的发生,从而能够有效提高穿孔顶头的使用寿命。该技术已运用于宝钢股份精密钢管厂,可完全利用现有的设备,成本低廉,容易推广使用。     

Maximal aerobic velocity measured by the 5-min running field test on two different fitness level groups

PURPOSE: A scleral plug made of biodegradable polymer implanted at the pars plana was evaluated to determine its ability to control the intravitreal release of ganciclovir. METHODS: Scleral plugs containing 25% ganciclovir were prepared with poly(lactic-glycolic acid) (molecular weight, 121 kDa). The release of ganciclovir was evaluated in vitro by spectrophotometry. In vivo intravitreal ganciclovir concentrations were measured by high performance liquid chromatography following plug implantation in pigmented rabbits. The biocompatibility of the device was determined by indirect ophthalmoscopy, electroretinography, and light and electron microscopy. RESULTS: The in vitro study showed that the plug released ganciclovir throughout a 10-week period. The in vivo study demonstrated that the plugs maintained the drug concentration in the vitreous in a therapeutic range adequate to treat cytomegalovirus (CMV) retinitis for 12 weeks. No significant retinal toxicity was observed. CONCLUSIONS: This study demonstrated that this drug delivery system can potentially be useful to treat CMV retinitis.     

四流中间包气幕挡墙水模拟研究

采用不同参数的多孔透气砖进行了25 t四流中间包的底部吹气水模拟实验,结合RTD曲线和标准差分析,研究透气砖面积(210～105 mm×56～28 mm) 、4种吹气位置和吹气量(60～120 L/h)对中间包液体流动特性的影响,并与不吹气的情况进行了对比。结果表明,中间包吹气能改善液体的流动特性,均衡其在不同水口间的停留时间,并能延长峰值时间和降低死区体积。透气砖靠近挡墙,采用小气量和小面积更有利于改善现有中间包流场。     

Numerical Simulation of Fluid Flow and Interfacial Behavior in Three‐phase Argon‐Stirred Ladles with One Plug and Dual Plugs

A numerical investigation is performed to describe the quasi‐steady fluid flow and interfacial behavior in a three‐phase argon gas‐stirred ladle with off‐centered bottom Ar injection through a plug and two plugs placed in 180° and 90°configurations, respectively. The flow of the fluid phase is solved in an Eulerian frame of reference together with the motion of every individually injected Ar bubble, tracked in its own Lagrangian frame. Volume of fluid (VOF) model is used to track any interface between two or more immiscible phases, which include slag/metal, slag/gas and metal/gas. The characteristics of fluid flow in a gas‐stirred ladle with one plug or two plugs configuration are described when the slag layer and the top gas are presented. The slag layer deformation and slag open‐eye formation at different Ar gas flow rates for three types of plug arrangements are given. The comparison of the mixing time, the deformation of slag layer and the behavior of slag/steel interface between one‐plug and two‐plug system is made. Several implications for ladle operational issues during a gas‐stirred ladle refining cycle are discussed. It is found that the proper selection of Ar gas flow rate and plug arrangements during a ladle refining cycle is required for different refining purposes considering the mixing and metallurgical reaction in a three‐phase ladle system.