双蓄热步进梁式加热炉的技术改造

介绍了福建三钢棒材厂蓄热式加热炉的改造方案及应用情况,采用两座双蓄热步进梁式加热炉解决了加热炉制约轧机能力提升瓶颈及冷热坯混装的问题,改造后取得了很好的经济效益。     

棒材厂加热炉步进机构在下降过程中出现颤振的现象分析与处理

<正>液压比例控制系统因系统较液压伺服系统容易维护,控制精度能满足生产需要,能量传递与重量比大等诸多优点,在冶金设备中得到广泛使用。棒材厂加热炉步进机构驱动系统为液压比例控制系统,通过两个液压油缸驱动步进框架在倾斜角20°的导轨上运动,将加热的钢坯按工作要求推至加热炉出钢位,通过出炉辊道将方坯输送至轧制工位。棒带材厂棒二线步进式加热炉步进机构在下降过程中出现轻微晃动。此时尽管步进梁上的钢     

国内大规格圆坯加热工艺现状分析与对策

国内大规格圆坯生产线应需兴起,成为钢厂的重要经济项目。加热过程作为主要耗能的轧前工艺,影响着大规格圆坯的产品质量和生产效率。大规格圆坯在加热过程中容易出现开裂,氧化、脱碳层过厚等问题,需要制定合理的加热制度来提高加热质量。同时,大规格圆坯的生产对加热炉垫块、步进机构等设备提出了更高的设计要求。文章总结了国内大规格圆坯加热过程容易出现的坯料质量问题和常见的设备缺陷,分析了大规格圆坯加热难点,提出了相应的改进对策。     

无水冷滑轨加热炉的设计及应用

介绍了加热高温合金钢坯的推块式加热炉,炉底采用无水冷滑轨结构,既能加热方坯又能加热圆坯,投入生产后取得较好的使用效果。     

昆钢650轧钢加热炉改造中40t推钢机可靠性校核

昆钢650轧钢生产线是1999年改造的年产650000 t小规格半连轧棒材生产线,坯料加热采用端进端出的推钢式加热炉,坯料尺寸选用150 mm^2×3000 mm的小方坯。由于草铺新区投产后,新建的型钢生产线还处于调试阶段,大方坯余存较大。公司计划将型钢厂剩余的230 mm^2×3000 mm的方坯约8000 t安排到650轧钢生产线进行生产。但由于新坯料的单根坯重是原用坯料的2.35倍,故必须对加热炉的承载能力和推钢机的进出钢能力进行核算,确定最优方案进行改造。     

车轴坯由方改圆的试验研究

为了进一步改善国内车轴坯和车轴的实物质量,挖掘现有锻轴设备潜力,提高车轴生产效率,将车轴生产原料由过去的方坯改为圆坯,试验其各性能水平。 试验采用与方坯成分相近的ZX8.3t钢锭热送初轧开成350×280mm矩形坯,堆垛缓冷,火焰清理钢坯表面缺陷后,送轨梁厂三段式连续加热炉再加热,然后通过“箱形—八角孔型系统”六道次轧成φ240mm圆轴坯,平放在台架上空冷至500℃以下堆冷。 经51炉(计4454t)圆轴坯从冶炼到加工成成品轴的试验证实:该工艺技术合理、工艺可行,所生产的圆轴坯各项指标均达技术标准要求,比方轴坯质量显著提高。     

方坯加热炉二维温度模型

开发了一种可用于方坯加热炉加热制度分析以及实时计算的方坯二维温度模型,该模型包括沿炉长方向的温度分布计算,方坯表面热流密度计算以及方坯内部二维热传导计算。加热炉炉长方向炉温分布根据热电偶测温数据获得;根据总括热吸收率方法计算方坯上、下表面的热流密度数值,并由此计算方坯侧面热流密度;对方坯内部热传导建立二维差分方程组,并利用ADI和TDMA算法进行求解。通过埋偶试验验证了模型方法的正确性,在某钢厂高线加热炉的运行测试表明,模型能够用于辅助制定钢种的加热制度,在线计算则表明了模型计算的通用性和实时性。     

棒材车间大规格坯料改造设计

本文简要介绍了某钢厂棒材车间原料坯由150×150方坯更换为170×170方坯的改造情况。从生产线现状、设备能力校核、工艺改造方案进行了阐述。该项目投资少,停产时间短,收益见效快,对于类似生产线的大坯料改造具有重要的参考价值。     

承钢蓄热式加热炉技术改造

介绍了承钢公司棒材生产线蓄热步进梁式加热炉存在的问题，大修改造方案的制定及实施。通过大修改造后，彻底解决了原来存在的问题，加热能力、加热质量大幅提高，氧化烧损大幅降低，燃烧更好控制，改造效果良好。     

步进底式加热炉的设计与操作

鞍钢小型厂二车间79年筹备改造,将原生产能力为10万吨的管坯车间改造为年产20万吨的半连续棒材车间。同年十月份动工,80年3月份投产。建两座小时能力为35吨的步进底式加热炉,加热普钢与低合金钢90方坯,供φ430/φ380/φ320等12台轧机组成的半连续机组轧制φ12～φ25园钢,螺纹钢,铆钉钢及标圆。投产后炉子单耗较改前下降37％。车间改造投资当年回收有余。鉴于炉子运行期间暴露一些缺陷,决定于83年10～11月份进行大修,其重点放在强化步进机构,改善液压系统,强化炉体绝热性能,进一步降低消耗,更适应生产需要。现就大修前后情况介绍如下。一、概况     

废水循环利用技术在电解锰生产中的实践应用

湿法冶炼电解金属锰生产过程中,需要使用大量的水进行冷却、冲氨、清洗等,水资源消耗量大,同时产生大量的工业废水,对环境保护造成极大的压力。对中信大锰矿业有限责任公司大新电解金属锰厂采用“零排放”废水处理工艺作了介绍,对工业废水实行源头控制、分类处理、循环使用,废水的处理取得了一定效果。     

Effective immunity to dental caries: passive transfer to rats to antibodies to Streptococcus mutans elicits protection

Rat dams, given intravenous injections of heat-killed Streptococcus mutans 6715, mutant C211 demonstrated significant agglutinin activity to the homologous S. mutans in colostrum, milk, and serum. This antibody activity was associated with the immunoglobulin G (IgG) class. High titers of anti-S. mutans antibody associated with the IgG class were also exhibited in the sera and saliva of the offspring that suckled these dams. After challenge with the homologous, live S. mutans, these offspring developed significantly fewer caries on all molar surfaces than did nonimmunized infected controls. A secretory immune response (manifested by the presence of specific IgA antibody to S. mutans in colostrum and milk) was elicited (i) in rat dams locally injected, in the region of the mammary gland, with heat-killed S. mutans antigen, and (ii) in other rat dams that were provided formalin-killed S. mutans in their drinking water. Offspring suckling these dams were challenged with virulent S. mutans before weaning and developed significantly fewer caries than did their infected controls. These findings clearly suggest that passively derived IgG or IgA antibodies to S. mutans are protective against dental caries.     

Counseling patients to quit smoking. What to say, when to say it, and how to use your time to advantage

Helping patients stop smoking is one of the most important--and frustrating--services primary care physicians can provide. Many physicians are reluctant to spend time talking about tobacco use with patients who show little or no interest in changing their habits. Fortunately, specific technique have been identified that can make the task easier. This article from the distinguished Nicotine Dependence Center of the Mayo Clinic looks at the "best practices" for dealing with nicotine dependence.     

Glutamic acid decarboxylase--gene to antigen to disease

Glutamic acid decarboxylase (GAD) enzymes catalyse the formation of gamma-aminobuturic acid (GABA), which is a major transmitter in the central nervous system but also exerts functions in peripheral organs. Recent-molecular analyses have revealed surprising new roles for the GAD isoforms in human diseases of autoimmune character including neurological disorders and insulin-dependent diabetes. In the 1995 Frontiers in Medicine Symposium, the co-authors of this review discussed the genetics, cell biology, molecular immunology and the role of GAD as autoantigens in human autoimmunity. Studies on disease diagnosis, prediction, and prognosis have revealed unique patterns of reactivities in both cellular and humoral immune responses. Further work will be needed to establish whether the GAD molecules can be used to treat autoimmune diseases.     

Reply to Hyman and to Levy.

Replies to the objections of A. Hyman (1981) and S. M. Levy (1981) concerning the author's (see record 1980-10503-001) rejection of psychotherapy as the treatment of choice in health-habit modification (HHM). The case is restated for a shift away from an emphasis on intrapsychic variables in HHM. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multimedia to teach urology to medical students

OBJECTIVES: To test the hypothesis that an interactive multimedia-based computer application may be used to teach urology to undergraduate medical students. METHODS: Third-year medical students rotating on their urology clerkship were studied. Student knowledge was measured with a multiple choice test administered in a pretest-post-test experimental design. The educational intervention was a multimedia-based application that presented a clinical module on hematuria, using natural language-like entries. Student attitudes toward the multimedia application were assessed by a survey. RESULTS: Twenty-three consecutive third-year medical students participated. Mean pretest and post-test scores +/- standard deviation were 35%+/-11% versus 74%+/-17%, respectively, P<0.0001. Student questionnaire responses indicated highly positive opinions that the multimedia-based module was easy to use, was fun, provided natural patient responses, had clear exercises, provided immediate feedback, was educational, and had a nonthreatening format, and that the multiple choice questions were clear and fair. CONCLUSIONS: Multimedia-based education may be used to teach urology to undergraduate medical students.