基于辊缝动态摩擦方程的铝板冷轧机垂振机理分析

针对高速铝板轧制过程中频繁出现的冷轧机垂直振动现象,结合轧制工艺润滑原理和机械振动理论,建立基于辊缝动态摩擦方程的轧机垂直振动模型.该模型由辊缝几何形状模型,轧辊-轧件工作界面的动态摩擦模型,变形区内的正向轧制应力、摩擦应力分布模型,以及单机架铝板冷轧机二自由度垂向系统结构模型组成.同时,为研究轧辊-轧件工作界面动态摩擦机制影响下的冷轧机垂振机理及系统稳定性,采用某厂单机架铝轧机设备及工艺参数,搭建Matlab/Simulink平台,分别模拟仿真轧制压力和正向轧制应力曲线,验证该模型的有效性;并讨论分析了变形区混合摩擦状态,轧辊-轧件表面粗糙度、轧件入口厚度与系统稳定性的关系.      

单机架可逆式冷轧机AGC系统

对单机架可逆式轧机厚度自动控制进行了介绍,并依据某钢厂８００单机架可逆式冷轧机的实际情况,在自控原理基础上,建立了该轧机的厚度控制系统模型。现场实际应用表明,该厚度控制系统明显提高轧制厚度精度满足实际生产的要求。     

单机架冷轧机全干扰耦合模型的建立与分析

在高品质薄板冷轧带钢生产中,板形、板厚和张力之间的耦合关系是近年来的重要研究课题。运用轧制理论系统地分析了单机架冷轧机轧制过程中所有控制量和干扰量对板形、板厚和张力的影响,并由此建立了单机架冷轧机全干扰耦合模型,而后采用Matlab/Simulink工具对该模型的耦合特性及干扰响应特性进行了仿真分析。该模型能够定量计算各因素对控制目标量的影响,较好地反映出单机架冷轧机的控制特性。在对模型分析的基础上指出了单机架冷轧机完全解耦设计和抗干扰设计的必要性。     

皮尔格冷轧异型管孔型设计

采用经典孔型的皮尔格冷轧机进行轧制,经常出现轧件表面质量较差和轧辊开裂的情况。由于轧制过程较为复杂,理论计算难以实现轧制过程数值分析,所以本文采用Solid Works对轧机以及轧件建模并使用ABAQUS仿真分析。本文对实际生产中的皮尔格冷轧管机轧制过程进行了仿真分析,得到其轧制规律、成品管质量缺陷和轧辊开裂的原因。提出新的孔型设计理念并建模仿真,得出新型孔型在轧辊强度和轧件质量上的优势。     

双机架四辊可逆冷轧机组辊系稳定性分析

轧制过程中辊系的稳定性影响轧辊轴承和轴承座等部件的使用寿命以及轧件质量。设置合理的工作辊偏移距,可保证轧机辊系在负载状态下满足稳定性的力学约束。针对双机架可逆冷轧机组,轧件要在两台轧机上往复进行多道次轧制,且两机架前、后张力设定策略不同的情况,结合现场实际轧制规程,分析了采用不同轧辊偏移方向时轧机辊系的受力状态,确定了保证辊系稳定的工作辊偏移距。研究结果可为双机架可逆冷轧机组辊系稳定性提供有益参考。     

首钢某热轧1580生产线轧机刚度分析

热轧生产线在轧制带钢过程中,工作辊所承受的轧制力,通过支承辊、支承辊靠枕、上阶梯垫、AGC液压缸、下阶梯垫、换辊滑座压板、换辊滑座底部滑板、轧机底板等零部件传递,最后由轧机牌坊所承受。承受轧制力的各个零部件将产生弹性变形,工作机架的总弹性变形可达几毫米。轧机工作机架的总变形分两部分:一部分由于工作机架的弹性变形,两轧辊轴向产生相对平移,使辊缝发生变化,影响板材纵向厚度称为轧机的纵向刚度,另一部分由于轧辊的弯曲变形影响板材的横向断面厚度差称为轧机的横向刚度。轧机刚度不仅影响轧辊的开口度和辊型设计,而且也影响轧机的调整和轧制工艺规程的制定。     

采用90Xφ过共析钢制造轧辊

苏联亚速钢厂轨梁轧机及大型轧机的开坯机架和毛轧机架,过去在轧制绝大部分的异型钢材时,采用材质为55X的锻钢轧辊。由于轧机转变到大量生产轻型的异型钢材,迫切需要耐磨性更好的钢质轧辊,因此,亚速钢厂首先采用了由高碳铬钒钢90XΦ制成的轧辊来轧制工字钢、     

GFM公司研制的高合金钢棒材轧机

最近GFM公司在奥地利研制了一套新型的特殊钢轧机,主要用于轧制高合金钢和工具钢,这套轧机由一列5机架可逆轧机和一列16机架45°轧机组成。16机架连轧机用于圆钢、方钢、六角钢的无扭轧制,每个机架的轧辊和进出导卫都装在一个可更换机架箱里,调换机架箱只需2～3分钟,一对轧辊有几个槽孔,     

新型十二辊带钢冷轧机

近年来,对小批量轧制产品的需求量越来越大,而且要求带钢越来越薄、强度越来越高。采用传统式带钢冷轧机生产这类产品严重影响生产率和产品质量。为解决此问题,日本川崎钢铁公司和三菱重工业公司联合研制出一种大压下量轧制、板形控制能力较强的单机架可逆式多辊冷轧机。新型轧机由12个对     

950mm单机架可逆六辊HC冷轧机异径轧制

依托异径轧制技术优势,在950 mm单机架可逆六辊HC冷轧机开展异径轧制工艺。采用在程序内增加控制系数的方法达到了同速控制,调整乳化液的浓度和皂化值,对平床过滤机和磁过滤器进行改造,优化轧制道次变形量,实现异径轧制后,降低了轧辊消耗,提高了产品的厚度精度、板形和板面质量。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

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。     

Results of treatment of cancer of the cardia

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.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

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)     

Comparison of rates of infection of two methods of emergency ventricular drainage

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.     

浅析《野草》的版画特征

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".     

四辊破碎机车刀架的改造

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。     

Effect of antibiotics of chemotaxis of human leukocytes

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.