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为了提高马钢CSP带钢产品的板形质量,在马钢CSP热连轧机板形控制模型中常规工作辊窜辊策略的基础上,结合平辊轧制技术的相关理论,提出了马钢CSP热连轧机末机架平辊轧制方案。试验结果表明,在末机架使用平辊,并结合变行程变步长的窜辊策略,有效地改善了轧辊磨损状况,提高了带钢产品的板形质量。 相似文献
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近年来热轧厂采用西马克CVCplus辊系的工作辊越来越多,而CVCplus辊系所产生的支撑辊磨损严重问题影响热轧厂的稳定轧制,尤其是在支撑辊末期,磨损严重影响到带钢板形质量与轧制稳定性,文章根据轧制公里数、轧制数据、轧制计划、轧辊性能等方面分析轧辊磨损过程,提出解决措施。 相似文献
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在热连轧带钢板形控制中,磨损和热胀会影响LVC工作辊的辊缝形状,进而影响到其板形调控性能,本文应用二维变厚度有限元法分析了不同轧制过程中LVC工作辊承载辊缝形状和承载辊缝凸度的变化情况,针对原有窜辊公式不能反映辊缝随轧制过程变化的缺点,建立了新型的LVC工作辊窜辊补偿公式以及相应的窜辊补偿策略,并将其成功应用在鞍钢ASP2150热连轧板形自动控制模型中,从而实现板形预设定的高精度控制.从现场轧制的带钢板形工艺数据可以发现,使用LVC辊形加窜辊补偿可以明显改善带钢板形质量,具有较强的实用性. 相似文献
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针对轧制电工钢时,精轧下游机架CVC工作辊不均匀磨损产生的各种质量问题,通过在精轧下游机架采用常规工作辊(平辊)辊形,结合L2周期性的往复窜辊策略,充分发挥精轧工作辊的长行程窜辊功能,解决精轧下游机架工作辊不均匀磨损导致的局部高点、楔形等异常断面轮廓形状等板形问题,进一步延长轧制公里数。 相似文献
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现代冷轧带钢凸度及板形控制技术的发展 总被引:3,自引:0,他引:3
概述了国际上广泛采用及最新应用的几种冷轧带钢凸度及板形度控制技术,包括:工作辊弯辊(WRB)、窜辊(RS)、轧辊交叉法(PC)、轧辊交叉及窜动(RCS)及动态板形辊(DSR)等. 相似文献
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针对七机架热连轧机组机架数量多,轧制工艺复杂,各机架控制能力得不到充分发挥而造成轧件板形出现中浪、边浪以及复合浪等问题,充分考虑七机架热连轧机组设备结构特点,同时结合轧制工艺条件,采用相对长度差法来表示轧件板形值,并以轧机有载辊缝为桥梁,根据辊系弹性变形模型与金属变形模型的耦合关系进行求解,建立热连轧机组板形预报模型。根据工作辊弯辊力和窜辊量对轧件板形可快速调整的特点,结合现场实际生产情况,确定工作辊弯辊力和窜辊量的研究范围,通过板形预报模型定量分析不同工作辊弯辊力和窜辊量情况下轧机有载辊缝凸度和轧件板形的变化过程,得到轧件板形的调控域,在此基础上提出板形综合控制策略。同时为了保证轧件凸度要求和避免轧辊过度磨损,提出各机架轧件出口厚度精度和辊间压力均匀度约束条件,并以各机架轧件板形波动最小为目标函数,对工作辊弯辊力与窜辊量进行综合优化,开发出适合热连轧机组板形综合控制技术。将该技术应用到某2 050热连轧机组生产实践,结果表明,典型规格产品在工作辊弯辊力和窜辊量优化后,轧件在热连轧过程中板形质量明显改善,轧件出口板形由10.5 I改善到4.8 I,现场应用效果良好。 相似文献
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通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。 相似文献
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K Ohta M Nishi M Ueda S Ohyama T Matsubara T Takahashi T Nakajima 《Canadian Metallurgical Quarterly》1998,99(9):589-594
Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients. 相似文献
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Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies. 相似文献
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鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美". 相似文献
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针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。 相似文献
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The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed. 相似文献