钛合金TC21车削用TiAlN涂层刀具耐用度试验研究

TC21是我国自行研制的第一个具有独立自主知识产权的高强高韧损伤容限型钛合金,广泛地使用在航空航天等领域;TiAlN涂层刀具广泛地应用于各种材料的切削加工。使用TiAlN涂层刀具进行了钛合金TC21的车削试验研究,通过单因素试验法研究了不同冷却条件、刀尖圆角半径和切削参数条件下的刀具耐用度情况,分析总结出后刀面的边界磨损和碎断破损是刀具主要的两种宏观失效形态,为TiAlN涂层刀具在钛合金TC21切削加工的推广提供了参考依据。     

硬质合金刀具高速车削钛合金的切削性能研究

采用单因素试验法,用未涂层硬质合金刀具和TiAlN涂层硬质合金刀具对Ti-6Al-4V钛合金进行了高速干车削试验,通过对切削过程中切削力、刀具寿命、切削温度以及加工表面粗糙度的分析,得出了两种刀具高速干车削钛合金的切削性能,为钛合金高速切削刀具的设计提供了试验依据。     

基于复合喷雾冷却的TC4钛合金切削温度的研究

钛合金是一种典型的难加工材料,其热传导率低,切削过程温升大而易加剧刀具磨损。本文通过对TC4钛合金的车削试验,研究了在干切削和复合喷雾冷却条件下切削温度随切削速度、切削深度和进给量的变化情况。结果表明:切削温度随着切削速度、切削深度和进给量的增大而增大;采用复合喷雾冷却技术可在TC4钛合金车削过程中取得较好的冷却效果,切削温度明显低于干切削条件下的切削温度。     

硬质合金刀具车削钛合金时切削力分形特征研究

分别采用硬质合金涂层和非涂层刀具对钛合金Ti-6.5Al-3.5Mo-1.5Zr-0.3Si(TC11)进行了干车削试验,通过试验中所测实验数据计算了切削力的关联维数,对切削过程中切削力的分形特征进行了研究。结果表明:切削钛合金时,切削力分维数随着刀具磨损状态的改变呈现高—低—高的变化规律;表面粗糙度和切削力分维数随切削时间的延续具有相同的变化趋势。     

润滑条件对TC4钛合金切削加工影响的实验研究

为了研究冷却润滑条件及切削参数对TC4钛合金的切削力和表面粗糙度的影响,分别开展CMQL、冷风、浇注式冷却润滑条件的TC4钛合金高速切削实验、四种不同润滑环境的粗/半精/精加工实验以及CMQL条件下TC4钛合金正交切削试验,通过单因素分析和正交试验法研究冷却润滑条件及切削参数对切削加工性的影响。研究表明：CMQL冷却润滑条件可在TC4钛合金高速切削时有效降低切削阻力和改善表面粗糙度,并在高速精车削阶段体现出降低切削阻力的优势。考虑CMQL条件下高速精车TC4钛合金加工效率,最佳参数组合为较高的切削速度、较小的精加工余量和合适范围内较大的进给量。     

基于干冰低温冷却的大进给铣削TC4钛合金刀具磨损研究

针对TC4钛合金切削加工过程中刀具易磨损、加工效率低等问题,以干冰为冷却媒介对TC4钛合金进行大进给铣削加工,以提高TC4钛合金的切削加工效率,降低刀具磨损。研究了不同冷却方式下的TC4钛合金大进给铣削过程中铣削速度对刀具耐用度的影响规律和干冰低温冷却方式下刀刃形状和刀具材质对刀具耐用度的影响;分析了干冰低温冷却方式下的不同铣刀刀具的磨损特征,明晰了干冰低温冷却大进给铣削TC4钛合金时的刀具磨损机理。研究结果表明,干冰低温冷却可以抑制大进给铣削时的刀具磨损,提高刀具耐用度。此外,圆弧刃三角形刀片比四边形刀片更适合高速大进给铣削。     

硬质合金涂层刀具车削钛合金TA15的磨损研究及切削参数优选

刀具磨损剧烈是钛合金切削中的突出问题,探求刀具磨损的本质对于提高加工质量和效率、降低成本具有重要意义。本文采用Al Ti N涂层硬质合金刀具对钛合金TA15(Ti-6.5Al-2Zr-1Mo-1V)进行车削试验,利用激光共聚焦显微镜观察刀具的磨损形貌,对刀具的主要磨损机理及磨损形式进行了分析,并根据刀具磨损状态进行了切削参数优选。研究结果表明:涂层硬质合金刀具切削TA15时,刀具失效形式主要为涂层剥落、崩刃和月牙洼磨损;随着切削速度的增加,后刀面VB值呈现了驼峰状的变化规律,涂层剥落的区域在波谷出现了明显的减小趋势;切削试验结果指出,正前角AlTiN涂层硬质合金刀具可用于钛合金TA15的精车工艺中,在v=100m/min、f=0.05mm/r、a_p=1.5mm切削参数下,刀具表现性能最优,同时硬质合金涂层刀具车削TA15的最大切削速度不宜超过120m/min。     

钛合金的高质高效超声振动切削加工

作为一种广泛应用于航空航天领域内的难加工材料,钛合金的高质高效切削一直是机械加工领域中的热点问题.针对其加工过程中的力热聚集问题,一种将高压冷却方式辅助于垂直于切削速度方向振动分离的超声振动切削加工方法被应用于其高质高效加工.首先,刀具和工件周期性的分离条件通过数学方法导出.随后基于此开展了钛合金的车削试验,通过设定不同的切削参数(切削速度、进给量和切深)和冷却参数(冷却液压力),研究了切削力、切削温度、刀具磨损过程、工件表面质量和刀具寿命与相关参数之间的关系.试验结果表明,在满足分离条件的情况下,高压冷却状态下的超声振动切削加工能有效降低切削力和切削温度、延缓刀具磨损速度、改善表面质量和提高刀具寿命.在冷却液压力20 MPa的条件下,钛合金的切削速度能提至400 m/min并保证工件表面质量Ra不超过0.4 μm,实现了刀具长寿命和工件高质高效的切削精加工.     

液氮低温切削钛合金实验研究

针对钛合金难加工特点,将液氮作为冷却介质直接喷向切削区进行钛合金TC4低温车削加工,测量其切削力、表面粗糙度和刀具磨损,并与干切削在相同实验条件下对比,分析低温切削对钛合金的影响。实验结果表明:低温切削钛合金,主切削力有所增大,但进给方向力减小,刀具磨损状况与表面质量得到改善,断屑相对容易。     

TC21钛合金封闭深槽腔大悬伸快进给铣削加工技术

从材料和结构介绍TC21钛合金封闭深槽腔类零件的加工特点。为了实现TC21钛合金结构件高性能加工,基于生产实践,从刀具选型、刀具轨迹、冷却方法、切削参数、刀具寿命等方面,研究大悬伸快进给刀具在TC21钛合金封闭深槽腔类零件上的高效切削运用,总结了一套完整的大悬伸快进给铣削方案。试验证明,悬伸比9倍径的快进给刀具能高效切削TC21钛合金深槽腔。对比强力铣削和插铣,快进给铣削提效明显。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.