结合在线电解修锐高效磨削陶瓷密封件研究

本文通过设计制作金属结合剂金刚石磨具，结合电解修锐技术对Al2O3陶瓷密封进行了研磨式磨削实验在实验过程中通过检测磨具表面的磨粒出露高度及陶瓷材料的去除量，评价该磨削工艺在陶瓷材料密封件加工中的应用效果。结果表明，电解修锐可有效地修锐金属结合剂金刚石磨具，在加工过程中使磨具保持良好的切削能力，因此材料去除量较大，加大工时短，陶瓷密封件的加工成本得到控制。     

轴承钢专用ELID磨削液的开发

针对轴承生产加工时磨屑不易排除导致砂轮黏附率大造成工件烧伤的难题,采用在线电解修整(ELID)磨削技术,在磨削过程中电解磨削液能够通过对砂轮表面阳极溶解的电解作用实现在线电解修锐及磨屑电解去除,从而达到良好的磨削状态,以对轴承钢进行精密、超精密磨削加工。结合已有ELID磨削液的开发经验,研制出更适合轴承钢磨削特点的专用磨削液。试验证明:采用HDMY-30磨削液磨削轴承钢,表面粗糙度Ra可达0.011μm,比采用原有磨削液磨削轴承钢的Ra降低了0.005μm。     

塑性材料专用ELID磨削金属结合剂砂轮的研制

本文在已有通用型ELID磨削用金属结合剂砂轮的基础上，根据塑性材料磨削的特点和ELID磨削过程特点以及在ELID磨削过程中砂轮电解修锐作用及生成钝化膜的效应，通过调整合金中各种成分的搭配比例，适量地增添四氧化三铁，使其有良好的电解成膜特性，优化出专用ELID磨削砂轮(BJUTL-SXI型)。     

在线电解修锐(ELID)磨削液的成膜特性实验研究

ELID技术是金属结合剂超硬磨料砂轮修锐的一种重要方法，ELID磨削液的选择是否合理将直接影响修锐的质量和效率。磨削液成份种类的选择以及它们之间的配比关系对砂轮表面氧化膜的生成速度、硬度、致密性、粘附性、以及绝缘性等方面都有很大的影响。本文针对青铜结合剂金刚石砂轮，对几组不同配比关系的磨削液进行了电解及成膜能力实验，通过观察电解过程电流的变化规律以及电解后阳极表面生成氧化膜的质量，较准确地对磨削液的成膜特性进行了评定，确定了磨削液配比优化方案，为青铜结合剂金刚石砂轮ELID磨削的实现奠定了理论与实验基础。     

ELID磨削预修锐与氧化膜成膜的影响因素

设计了蓝宝石ELID(在线电解修整)磨削工艺的实验装置和实验方案.基于电化学理论,建立了蓝宝石ELID磨削预修锐氧化膜形成的数学模型,定性分析了氧化膜的成膜过程,并通过磨削实验,研究了极间间隙、电压等工艺参数对预修锐时间的影响规律,揭示了氧化膜厚度和生长速率的变化规律,提出了基于厚度、粘附力和孔隙率,并考虑预修锐时间的氧化膜状态的评价表征方法,对极间间隙、脉冲频率、电压和砂轮转速等ELID电解加工参数进行了优化.实验获得最佳加工条件为极间间隙0.5 mm,脉冲频率90 kHz,电压120 V,砂轮转速1500 r/min.     

轴承钢专用ELID磨削液电解成膜性和防锈性研究

介绍了ELID磨削技术原理,通过静态模拟试验对通用磨削液HDMY-20和新研制的轴承钢专用ELID磨削液HDMY-30的电解成膜性进行对比分析,并探究防锈剂质量分数不同时磨削液HDMY-30的防锈效果。结果表明:磨削液HDMY-30的电解成膜性优于HDMY-20,其电解电流最大值比HDMY-20高2 A,成膜时间也缩短约2 min,完全满足轴承钢加工中砂轮的在线电解修锐及表面磨屑快速去除的要求;当防锈剂质量分数达19%时,磨削液HDMY-30在保持强电解成膜性的同时兼具良好的防锈性。     

辅助侧向吹气法金刚石砂轮激光修锐试验与评价

介绍了辅助侧向吹气法金属结合剂金刚石砂轮的激光修锐试验和简化测力评价方法,计算比较了修锐前后砂轮磨削力、磨削力比和比磨削能,从不同角度说明了辅助侧向吹气法对激光修锐金属结合剂金刚石砂轮的有效性。分析了修锐前后砂轮表面与对应磨削试件表面的微观形貌机理,解释了影响磨削力变化的因素。采用辅助侧向吹气法能够解决金属结合剂砂轮激光修锐中常见的熔化覆盖问题,使砂轮磨削力比同轴吹气法修锐下降5％～7％,激光修锐砂轮的磨削性能得到明显改善。     

淬硬轴承钢硬车削和磨削辅助加工技术研究

为提高轴承套圈表面加工质量及生产效率,在硬车削、磨削中引入了辅助加工技术。介绍热效应、冷效应、超声振动硬车削辅助加工技术,以及超声振动、冷效应、在线电解修整砂轮磨削辅助加工技术,分析了各辅助加工技术的优缺点,并展望了硬车削、磨削辅助加工技术的未来发展趋势。     

非球面模芯ELID磨削系统的研制

针对非球面模芯超精密磨削加工问题,研制了在线电解修锐(ELID)磨削系统。该系统应用平行法磨削原理,用整形后的球头砂轮进行非球面模芯的超精密磨削加工;利用非球面模芯工件本身的导电性能,以铸铁结合剂CBN砂轮作为阳极,以模芯本身作为阴极,通过ELID电源参数(电流、电压、占空比)的合理选择,解决了CBN球头砂轮的修锐,稳定地实现了小口径非球面模芯的ELID超精密磨削加工。     

基于放电修锐的粗金刚石砂轮干式镜面磨削技术

为解决超硬金刚石砂轮修锐效率较低以及环境友好性等问题，采用干式接触放电修锐(ECD)技术对粗金刚石砂轮进行修锐，获得较高的磨粒出刃，可以实现硬质合金和模具钢等高强高硬材料的高效精密镜面磨削加工。对46#金属结合剂粗金刚石砂轮进行机械修锐和干式ECD修锐，再利用修锐后的粗金刚石砂轮对硬质合金和模具钢进行干式轴向磨削加工，对比分析两种修锐条件下磨削工艺参数对硬质合金干磨削力、磨削表面粗糙度和磨削力比的影响。实验结果表明：硬质合金的干式轴向磨削力及其表面粗糙度随砂轮速度的增大而减小，随进给速度和切削深度的增大而增大；与机械修锐相比，干式ECD修锐能够获得更高的磨粒出刃和更好的表面质量，以及更小的磨削力和磨削力比；硬质合金和模具钢的干磨削表面粗糙度Ra分别可达0.058μm和0.022μm。     

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.     

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.     

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....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.