枪钻系统DF钻系统振动切削深孔加工技术通过部级技术鉴定

由陕西机械学院西安深孔加工技术研究中心承担的国家“七五”期间重点科技攻关项目——枪钻系统、DF钻系统振动切削深孔加工技术,于1990年6月通过机电部科技司、机床工具所组织的部级鉴定。本项目是结合我国当前容量最大的60万千瓦汽轮机生产中难加工材料小直径精密深孔加工进行的。课题组经过近五年的努力,在全面的理论分析与试验研究的基础上,形成了两种新型深孔加工系统——振动切削枪钻系统和DF钻系统,并经生产验证,均已达到实用化程度,技术先进,性能可靠。     

深孔加工技术及其应用

评述了五种深孔加工系统——麻花钻系统、枪钻系统、BTA系统、喷吸钻系统、DF钻系统的特点与应用,以及振动切削技术在深孔加工中的应用。     

和田玉机械式振动深孔钻削系统设计

基于和田玉材料高硬度、高韧性的特点,设计一种外排屑机械振动式深孔钻削系统,完成了加工系统主要部件钻头、振动系统等的设计与仿真。研究了枪钻低频振动方式深孔振动钻削系统理论,为后期和田玉超声波深孔加工机理及其裂纹预防策略研究提供了一定理论支持。     

深孔钻技术的应用与研究

介绍了一种深孔加工的专用刀具——枪钻的具体结构及其加工原理.同时还介绍了枪钻的使用要求及切削参数的选择以及在使用过程中应该注意的要点.     

基于三导向条结构的枪钻深孔加工动力学分析及圆度误差优化

为了改善深孔加工的圆度形貌,依据枪钻深孔结构与加工中的实际受力情况,结合导向块对提高孔加工圆度形貌所起到的作用,设计出具有三个导向块的优化结构。在保证计算精度的前提下,通过有限元分析法及力学模型的特征矩阵推算出深孔加工过程中出现圆度误差的数学表达,并通过数值仿真分析与实验研究,对比分析了两导向块结构和三导向块结构枪钻在相同的加工条件下圆度误差形成的情况。计算结果表明,三导向块结构的枪钻加工孔的圆度误差更小。可见,三导向块结构可以有效降低圆度形貌变形的出现,提高加工质量。     

基于枪钻系统的数控车床应用分析

核反应堆堆内构件是核设备中最关键设备之一,此类构件需要承受高中子注量的辐照和冷却剂的腐蚀,且要在高温、负载工况下保持足够的强度.针对武汉某用户核反应堆堆内构件上支撑柱、堆芯支撑柱、堆芯二次支撑柱及下部导向组件焊后加工深孔的问题,长沙金岭机床有限责任公司生产的CKD6183×3000数控车床上引入了枪钻系统,解决了此类组件焊后加工深孔问题,不仅满足了用户提出的精度要求,而且降低了操作者劳动强度,提高了生产效率,成功实现了高速、高精度、高效率加工深孔,摸索出了在此类组件焊后加工深孔的另一种新方法.     

深孔加工技术研究

深孔加工与普通孔的加工有所不同,其中有些孔的加工精度和表面质量要求较高,而且有的被加工材料的切削性能较差,加工更加的困难。通过简要阐述深孔钻削加工的特点,刀具的结构,并通过介绍在钻削加工过程出现的一些问题,提出了以下改进措施,从而改善了深孔加工中冷却、断屑、导向问题,提高了钻削的性能,降低了成本,提高了产品的精度。     

15-5PH不锈钢深孔枪钻加工切屑成形的机理分析

深孔枪钻加工过程中,被加工孔直径小、孔深长,切屑形貌是影响其加工质量的一个重要因素,并且切屑的成形机理和与工艺参数之间的关系也一直是深孔加工研究的难点。本研究以15-5PH不锈钢为研究对象,通过对切屑的流动过程分析,研究枪钻加工螺旋形切屑成形的过程和影响因素。借助扫描电镜检测切屑断面不同点的形貌,研究15-5PH不锈钢枪钻加工切屑的断裂机理。通过改变切削速度、进给量和油压的试验,分析了不同工艺参数下的切屑变形规律。借助ANSYS-FLUENT仿真软件,分析不同油压枪钻前刀面刃口的流体压力和湍流动量,阐述了切屑变形与油压的影响关系。研究发现15-5PH不锈钢深孔枪钻加工切屑属于"准解理断裂",切屑形貌与枪钻工艺参数选择密切关联;本研究的结果对15-5PH不锈钢深孔枪钻加工工艺参数和冷却液油压的优化选择具有指导意义和参考价值。     

深孔加工中振动的产生原因和消除方法

深孔加工是在封闭的条件下进行的高难加工工序,振动问题是深孔加工中比较难解决的问题。文中阐述了深孔加工中振动的类型;分析了深孔加工中振动问题产生的原因,对钻杆弹性变形引起的振动这一主要原因进行了分析;结合一台深孔钻床和钻具研制过程,提出了深孔加工中消除振动的方法。     

汽车发动机连杆螺栓拧紧力矩和装配工艺分析

文章分析了发动机工作时连杆螺栓所承受的工作载荷和影响拧紧力矩的因素，提出了连杆螺栓的装配工艺要求。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that