酒钢热镀锌机组双切剪剪切模式研究

双切剪是酒钢镀锌机组入口段重要设备,负责切除原料卷带头带尾,保证焊接质量.在实际生产中,钢卷长度无法完全精确计算,尾部剩余长度也存在着偏差,双切剪分切成的废料总会存在长度不等的小块,当尺寸过小时,有可能卡入剪刃,从而导致生产线停机事故.介绍了一种新的尾部剪切模式,可避免切尾过程中小块的产生,保障生产的顺利进行.     

凹型底板在上注中的应用

众所周知,在钢锭轧成钢坯的过程中,由于心部和边部的变形不同,造成了钢坯端部中间的延伸小于两边的延伸,形成了鱼尾或尾孔。鱼尾或尾孔的发展愈严重,切除的就愈多,金属的收得率就越低,即成坯率越低。根据鱼尾或尾孔形成的原因,把平底钢锭设计成凸底钢锭,以减少轧制过程中心部与边部的延伸差,将能有效地消除鱼尾和尾孔,减少钢坯尾部的切损,提高钢锭的成坯率。武钢一炼钢厂上注工艺原用平型底板和上小下大的F8.2钢锭模匹配,铸出的平底钢锭的实际切尾率约3%;1986年改用凹     

用双层底板浇铸凸底钢锭投入生产

我国大中型炼钢厂浇注钢锭绝大多数是采用单层底板下注操作,钢锭的底部是平的,在初轧成坯过程,钢锭尾部形成鱼尾孔而作为废品切除。切尾率随钢锭大小和初轧机能力的相互关系有所不同,一般约占钢锭重量的3％左右。如果钢锭偏大或轧机偏小,则切尾率会增加。把钢锭底部形状由平底改为凸底,在开坯过     

双层底盘试验总结

本文介绍了采用镶嵌式底盘浇注的沸腾钢凸底钢锭的试验,试验结果表明,其钢锭切尾率可小于1.0%;镶嵌式底盘定位只要底盘与锭模的配合公差选择适当可以消除钢坯尾部的折叠缺陷;采用合理的轧制工艺可得到最佳的钢坯尾部形状。     

无头产线的切头剪剪切优化与应用

切头剪是现代轧钢产线中的一个关键设备,切去中间坯的头部和尾部,切头剪切头、切尾的精度控制非常重要,直接关系到轧钢成材率和产品质量。本文主要是研究无头产线中切头剪在切头位置跟踪、切尾位置跟踪和剪切点的计算方法,根据现场实际生产状况,分析切头、切尾误差较大的原因,并逐步优化剪切控制程序,提高剪切精度,达到工艺要求。     

IF钢非稳态浇注铸坯洁净度分析

为系统分析某钢厂IF钢在非稳态浇注时铸坯洁净度的变化情况,采用气体分析、成分分析、大型夹杂物分析等方法对在非稳态条件下生产的IF钢的头坯、尾坯、换水口坯进行分析。结果表明:头坯内N、T.O、大型夹杂物含量沿拉坯方向逐渐降低,Als含量逐渐升高,头坯前8.5 m不适宜IF钢生产,尾坯距尾部2.5 m内N、T.O、Als含量波动较大,距尾部4.5 m内大型夹杂物数量较高,均在1.41倍以上,尾部4.5 m必须切除;换水口坯在换水口位置的前后1.5 m内T.O、N、大型夹杂物含量明显升高,在IF钢生产中应进行切除。     

一炼钢近年来提高成坯率的生产实践和展望

为努力提高经济效益,提高钢锭成坯率是各冶金企业始终追求的目标。对于炼钢厂而言,实现这一目标主要途径有二:一是改善钢锭头、尾部的形状,尽量减少切头和切尾;二是改善钢锭的内部和表面质量,减少因产生轧后废品而导致的补切。围绕提高成     

减少钢坯剪切时的金属消耗

在开坯车间轧制钢锭金属消耗的主要原因是不合理的切头切尾。钢厂按现行工艺,广泛采用重量7.89—8.24吨的上注钢锭轧制330×450毫米和320×335毫米的大钢坯。钢坯头部剪除长度不超过轧件总长的14.5％,尾部剪除则为2％以下。头部要除去凸端再多剪去50—100毫米。这就多切掉了钢锭本身有用的部分。     

板坯连铸机无水封顶技术的开发与应用

传统的连铸机打水封顶工艺技术存在尾坯质量差、探伤合格率低、坯尾切除量大的缺陷。为解决某宽厚板企业连铸机尾坯质量差的技术难题,该公司通过工艺技术创新,研究开发了宽厚板连铸机无水封顶技术,变"打水"为"无水",该技术实施后,尾坯内部质量得到了较大改善,尾坯探伤合格率从78.2%提高到了98.8%,坯尾切除量从1.5~2.0 m降到0.8 m。     

无取向电工钢头尾磁性能波动分析

针对无取向硅钢工业化生产过程中出现的带钢头、尾磁性能波动现象,采用OM、XRD、EBSD技术对显微组织和晶体织构进行分析研究,结果表明:(1)受温度波动影响,距离尾部越近,带状组织越严重,距离尾部25m处芯部仍存在带状组织;(2)带钢头、尾平均晶粒尺寸较中部小7～10μm,是造成头、尾铁损降低的直接原因;(3)相比于带钢中部,头部试样不利织构{111}〈112〉减少了2.8%,但是有利织构{100}〈010〉也降低了1%,导致磁感应强度相差不大。     

Changes in the ultra-fine structure of capillaries of the embryonic brain in the presence of schizophrenia in the mother

The report is concerned with a study of fine structures of brain capillaries in 9 embryos received during medical abortions from schizophrenic mothers. The authors established some traits in the ultrastructure of endothelial cells in most of the studied cases--an increase of the surface of endothelial cells at the expense of a tortuosity of their plasmatic membranes and a formation of growths, vacuolization of the cytoplasma. There were also some changes in the structure of basal membranes. In 2 cases there were also peculiar pathological changes in the vascular endothelium: granules of an unknown nature in the endothelial cells and a focal lysis of the plasmatic membranes of endothelial cells.     

不同除草剂在直播冬油菜田的除草效果研究

[目的]验证不同除草剂的除草效果,为直播冬油菜田的杂草防除提供借鉴.[方法]使用不同剂量25%胺苯磺隆可湿性粉剂和10.8%高效氟吡甲禾灵乳油在直播冬油菜田间进行单用和混用除草试验.[结果] 25%胺苯磺隆可湿性粉剂在冬油菜4～5叶期使用可以有效防除田间的阔叶杂草;25% 胺苯磺隆可湿性粉剂18.0～22.5 g/hm<'2>+400 ml/hm<'2>的10.8%高效氟吡甲采灵乳油可以有效防除油菜田间的阔叶和禾本科杂草,总防效达90%以上,且可以比人工除草节省成本1 100元、hm<'2>.[结论] 25%胺苯磺隆与10.8%高效氟吡甲未灵乳油混用可以更好地防除冬油菜田间杂草.     

Simulation of the solidification of the melt in the Vanyukov furnace in the case of emergency stoppage

A mathematical model of the Vanyukov furnace, which makes it possible to predict the behavior of an object in the emergency operational mode (upon the disconnection of the oxygen supply) and develop an effective system of additional heating which damps the consequences of the emergency mode and lowers the costs for the renovation of the furnace operation, is created. It is shown how solidification upon cooling the furnace with time is simulated using the enthalpy and porosity method. The mathematical model is adopted for existing production conditions, which are weakly defined. The energy characteristics of the mode for the solidifying furnace bath, which ensures its holding for a long time in the ready state to rapid firing, are found. Thus, the problem of excessively expensive furnace firing after prolonged production stoppage is solved in the conjugated statement with a calculation of the heating system of the overbath space.     

Variations in the relationship of the major vessels of the left coronary groove in the dog

The anatomic relationship of the 2 major vessels of the left coronary groove was studied in 140 dogs. Five basic patterns of disposition were observed: 1) circumflex artery superficial from its origin to the caudodorsal cardiac margin, coronary vein deep and not visible (22%); 2) coronary vein superficial from the ventral interventricular septum to the caudodorsal cardiac margin, circumflex artery deep and not visible (15%); 3) circumflex artery and coronary vein both superficial and running parallel with each other along the groove (8%); 4) coronary vein crossing circumflex artery at some point along the groove (44%); and 5) circumflex artery crossing coronary vein at some point along the groove (11%). These variations were found to influence certain experimental modifications of the left circumflex blood flow in the dog.     

Errors in the surgery of the testicle in children

The study was made of labyrinthine changes induced by lasix dehydration. Changes indicative of Meniere's disease were identified at comparison of the findings obtained by audiological lasix test, caloric optokinetic reactions. Four types of the nystagmic response in the bithermal lasix-test were determined. These reactions are helpful for more precise staging of the disease.     

Role of the subthalamo-nigral input in the control of amygdala-kindled seizures in the rat

The substantia nigra pars reticulata (SNpr) is a critical site for the control of epileptic seizures. Potentiation of the inhibitory GABAergic input from the striatum to the SNpr suppresses primary or secondary generalized seizures in the rat. The purpose of this study was to examine the possible involvement of the excitatory glutamatergic input from the subthalamic nucleus to the SNpr in the control of both the electroencephalographic and the motor components of amygdala-kindled seizures in the rat. Microinjections of either an N-methyl-D-aspartate (NMDA) antagonist in the substantia nigra or a GABAA agonist in the subthalamic nucleus, significantly reduced motor seizures but did not modified the afterdischarges. These results provide evidence for the involvement of the subthalamo-nigral projection in the modulation and the propagation of the motor components of amygdala-kindled seizures.     

Regional differences in the distribution of catalase in the epithelium of the ocular lens

The objectives of this study were to develop a system to calculate the economic consequences of accidents and to account for the economic consequences of all accidents during 1 year in a district. A total population injury survey was done in an area with a population of over 41,000. All accidents (N = 4926) occurring within a 12-month period and requiring medical care were noted. The costs (calculated at 1991 prices) to the health care service (outpatient care, including primary health care and hospital care) were SEK 23.7 million (US $3.59 million), to trade and industry SEK 79.7 million (US $12.08 million), and for health insurance SEK 9.1 million (US $1.38 million). The cost for society of uninsured people is not possible to estimate using loss of production. However, the time lost from "normal activities" was registered. If this time is valued at the same price as working hours, a welfare cost of SEK 43.1 million (US $6.53 million) should be added. In a forthcoming paper, an assessment of the cost-effectiveness of interventions against accidents will be published.     

A change in the state of neurons of the arcuate region of the hypothalamus in different stages of the sexual cycle in rats

With the help of microionophoretic stimulation of individual neurons of the arcuate region of the hypothalamus and the registration of its activity, changes in the sensitivity to dopamine during several stages of the sexual cycle of rats was studied. It was shown that in the 1st half of the day of proestrus the majority of neurons of the arcuate region, in correspondance to the increase in the level of estrogens in the blood plasma during this phase of the cycle, were activated by microionophoretic injections of dopamine. In the 2nd half of the day of proestrus, when the level of estrogens is minimal, and in the Diestrous-2 stage, it was observed that among registered neurons, those activated by dopamine were the most inhibited.     

On the role of self-excitation in the development of topographic order in the visual system of the frog

A two-level model is presented for explaining the development of the topographically ordered retinotectal connections of the visual system of the frog. The columnar structure of the tectum were taken into account explicitly. Simulations suggest that the self-excitatory intracolumnar connections play an important role in the formation of the topography. In the case of self-excitation the system is able to recognize the topology of the visual field by the continuity of the object's movement.     

The role of the forestomachs in the adaptation of the alimentary function in ruminants

Dietary character of ruminants in the north is principally different between "nonselective" (cattle, sheep) and "selective" (reindeer, moose) species. Due to the developed polyfunctioning, forestomach in ruminants, primarily rumen and reticulum, are involved in the homeostasis formation in enteral and interior mediums, nutrients deposition and recirculation. That provides efficiency in utilization of deficient in nutrients forage and body reserves of wild ruminants during the winter. The original functional organization of absorption processes and nutrients recirculation across the multilayer epithelium of forestomach also promotes realization of the two levels metabolism during the year and adaptation of wild ruminants to season dynamics of nutrition.