目前钢管生产新工艺CPE轧机生产线

在西德克莱芬斯厂的阿塞尔轧机上安装了液压抬辊系统、生产出89.5×2.6的薄壁管。采用Assel轧机抬辊法同样可以生产出Transval轧机的转角法轧制D/S比在35的薄壁管。Transval轧机的转角法与Assel轧机拾辊法的优缺点比较:1.旋转法是在刚开始时搞的、轧制速度慢。2.旋转牌坊重量很重、要在短时间0.1秒     

不同轧制方式下TC4轧管变形分析

采用ABAQUS模拟软件模拟了PQF轧机、Accu轧机、Assel轧机轧制TC4钛合金管坯的过程,分析轧制过程的截面形状、温度、应力、应变的变化。结果表明:PQF轧机轧制TC4无缝管过程中截面形状较Accu和Assel轧机轧制TC4无缝管时截面形状变化小,尺寸精度高;Accu轧机和Assel轧机轧制过程中应力分布较PQF轧机复杂;采用3种方式轧制时,壁厚内侧金属应变较外侧大;Accu和Assel轧机轧制时间短,温度下降较PQF轧机小。     

WC板带轧机设计要点和异径辊的轧制效果

本文提出了WC轧机采用异径辊轧制的轧制技术,并用塑性加工原理分析了轧制时金属的静水压力、单位轧制压力以及中性角与普通四辊轧机进行比较,提出了WC板带轧机的设计要点。最后指出,充分发挥四辊轧机最大作用的途径是采用异径辊轧制的WC轧机。     

新二辊钢管斜轧延伸机工艺理论

本文提出了一种新的二辊钢管斜轧延伸机,这种延伸机是采用带有“双减”辊型的轧辊、半浮动芯棒和导板。试验证明,这种轧机不论在产品品种上、产量上和质量上还是在消耗指标上均可和国外发展的Assel、Transval和Diesher轧机相竞争,而且有其一定的优点。文中着重阐述了新延伸机的工艺理论,即金属变形和流动、滑移问题、轧制力参数以及咬入条件等。     

Assel轧管机轧制薄壁φ70 mm×3 mm合金结构钢管工艺研究和辊型改进

现场实验研究了Assel轧机轧制过程减径量、减壁量、牌坊转角、钢管径壁比(d/t)和转速对20Cr钢管扩径量(△d)、壁厚不均匀度(△t)和轴向滑移系数(ηo)的影响.设计了轧制φ70 mm ×3 mm 20Cr钢管的辊型.工业生产结果表明,毛管尺寸为φ76.3 ～76.7 mm×7.89 ～8.36 mm,Assel轧机轧制参数为喉径58 mm,芯棒52mm,转角15°,转速200 r/min时可轧出符合标准要求的φ70 mm×3 mm的20Cr钢管.     

2500 mm中厚板精轧机支承辊辊型优化设计

 针对国内中厚板轧机多采用平辊轧制的现状,根据国内某2500 mm中厚板轧机机型特点,建立了支承辊辊型优化目标函数,采用4次曲线作为四辊轧机支承辊最优辊型曲线形式,提出了辊型优化的设计方法,提高了板形控制效果和成材率。     

棒材自由规格减定径轧制技术

为满足用户对圆钢产品小批量多规格的要求,解决连轧机经常换辊的问题,可以采用自由规格减定径轧制技术,即在棒材连轧机后增设规圆机组,规圆机组的轧辊配置有二辊、三辊和四辊,通过调整辊缝不更换孔型的方式,满足小范围内改变产品规格的要求。但轧件的精度除取决于轧机精度外,变形方式也是重要因素,要避开晶粒粗大区,同时必须控制轧件的自由宽展。设置定径轧机,可将 20～40mm热轧圆钢的尺寸精度由±0.5mm提高到±(0.1～0.2)mm。     

切分轧制

切分轧制又名并列轧制,是一种高效轧制方法。这种轧制工艺的特点是利用轧辊孔型的切分作用,将坯料轧成数根并列的轧件,然后通过特殊设计的切分装置将轧件沿纵向切分,再进一步加工为成品。采用切分轧制工艺可以使轧机的设计紧凑,产品规格多样化,提高小     

叠轧薄板轧机单机多片轧制

二辊周期式热轧薄板轧机的生产方式有两种。一种是开坯和精轧在同一台轧机上完成,叫单机轧制。另一种是一台荒轧机专为板坯开坯,另一台精轧机用来精轧成品,叫双机轧制。荒轧机的形式可以是二辊式或三辊式的,可以用热辊轧制,也可以用冷辊轧制。国外一般都采用双机轧制,不久前西德为某亚洲国家设计的一个薄板车间就是一个荒轧机配一个精轧机。在国内,对采用双机轧制还是采用单机轧制,也有过长时间的争论。通常认为,单机轧制时虽然开坯与精轧之     

2800mm中板轧机幂函数曲线辊型的研究

根据中厚板轧机轧制力和轧件宽度变化范围大的特点,在研制2800mm轧机辊型中,通过引进压力加权系数和宽度加权系数,使设计出的幂函数曲线辊型能自适应于生产中各品种规格的变化,特别是实现了工作辊辊型在支撑辊的整个服役期内可保持不变的目的,从而大大简化了工作辊的管理和储备量.生产实践表明,该辊型使用效果显著.     

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.