轧机液压压下油缸摩擦力的测试

本文论述了板带材轧机液压压下油缸摩擦力测试的基本原理，提出了基于CAD常用功能的计算液压压下油缸摩擦力的新方法——面积法。     

轧机液压压下油缸的新型组合密封

当工作环境较差、工作压力较高时,液压机的油缸往往都采用多层的夹布橡胶人字形密封。经验证明,这种密封是可靠的,但其摩擦力非常大。当要求运行摩擦力及起动摩擦力都很低时,这种密封就不适合使用。在轧机液压压下系统中采用电液伺服阀实行位置控制的压下油缸,就要求如此。此外,在一些液压测试装置和伺服机构中,以及利用液压来秤重或测力的仪器油缸里,都需要及时动作且又能准确反映出油压的数值。因此,就要寻求一种能够满足上述要求的新型密封。 下面介绍一种用在液压轧机压下油缸     

轧机用AGC液压缸测试系统探究

介绍了AGC伺服油缸设计和生产的技术要求,建立测试平台,对伺服油缸静态和动态指标进行测试.测试过程中,采用对称布置的双位移传感器结构,二级高精度伺服阀,控制系统采用位置闭环和压力闭环控制.测试后,得到了活塞腔保压压力及活塞杆位置随时间变化的关系.AGC油缸的阶跃响应、频率响应特性.油缸的启动摩擦力、动摩擦力特性及活塞杆的偏摆特性.经过测试的AGC油缸已经应用到实际生产中,效果良好.     

1200冷轧机压下油缸的设计

沈薄１２００四辊轧机原电动压下系统存在很多不足，已不能满足轧钢生产的需要，因此将其改造成液压ＡＧＣ系统。介绍了设计要求和其压下油缸的设计。新的液压压下设备投入使用后，收到了显著效果。     

1200冷轧机压下的油缸的设计

沈薄１２００四辊轧机原电动压下系统存在很多不足，已不能满足轧钢生产的需要，因此将其改造成液压ＡＧＣ系统。介绍了设计要求和其压下油缸的设计。新的液压压下设备投入使用后，收到了显著效果。     

5机架冷连轧机压下分配模型及应用

为了获得5机架冷连轧机最佳的压下分配,并为过程控制系统设定计算模型提供精确的数据,根据冷连轧机工艺特点,对冷连轧机的压下分配模型进行了研究,建立了压下分配非线性模型。利用拟牛顿法求解此模型,同时,设计了模型的计算流程图,并开发了相应的实现程序。此模型已成功应用于某5机架冷连轧机的压下分配计算及过程控制系统中。     

浅谈轧机液压压下装置

本文结合工作实践，介绍了轧机液压压下系统的组成、功能及其特点。对压下油缸、液压系统和厚控模式等有关问题进行了分析讨论。     

轧制伺服油缸试验台测试缸控制系统仿真研究

提出一种轧制伺服油缸试验台研制方法,此试验台能进行动态响应特性和摩擦力测试.并建立试验台测试缸液压控制系统数学模型,利用大型仿真软件MATLAB对模型进行时域、频域的仿真研究.     

减少液压压下油缸摩擦力的措施

板带轧机中的厚度自动控制油缸,是调节辊缝位置、控制轧制力大小、实现APC、PGC功能的执行机构。油缸要动作灵敏,定位准确,摩擦力小,才能较好地完成所承担的任务。当从油缸中取压力反馈信号时,如油缸的摩擦力为轧制力的2％,在2000t轧制力、轧机刚度为1/500mm/t的情况下,就会给辊缝位置带来2000×0.02×1/500=0.08mm的误差。可见摩擦力过大会降低油缸的灵敏度和精度,使板带成品的纵向误差加大;同时这种非线性的摩擦力还会引起压力反馈系统的低频振荡,而这种振荡又很难采用理想的校正环节来加以消除,因此降低了系统的动态品质。 1.油缸摩擦力的产生     

液压压下油缸在中板轧机上的应用

专门为上钢一厂2350mm四辊可逆式中板轧机设计的液压压下油缸,代替了原有的电动压下机构。自1984年8月投产,使用至今,证明这套油缸运转情况良好,工作可靠,已达到工艺生产要求的各项指标。 该油缸结构如图所示。它的全高520mm,活     

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.