等离子体表面淬火热处理工艺的研究

通过试验获得了用等离子体作为热源对45号钢进行表面淬火热处理的最佳工艺参数,并简要分析了各种工艺参数对淬硬层硬度、深度、淬硬带宽度的影响规律.45号钢经等离子体表面淬火后,硬度在800 HV左右,表明采用等离子体热源对工件进行热处理是可行的.     

等离子体表面淬火影响因素及最佳工艺参数

通过对45钢的等离子体表面淬火试验及金相分析，探讨了等离子体淬火工艺参数对材料硬化效果的影响规律，并得出最佳淬火工艺参数。     

基于通道模型计算等离子弧表面淬火热源参数

以通道模型和Maecker线性化方法为基础,结合等离子弧表面淬火的工艺过程,从理论上对等离子弧表面淬火热源参数进行分析计算,获得了等离子弧表面淬火热源热流密度分布的表达式,并通过ANSYS软件,将计算结果应用于45#钢等离子弧表面淬火过程的温度场模拟中,得到了45#钢工件的淬硬层深度和宽度,通过与45#钢的淬火实验结果对比,两者在误差范围内非常吻合,从而验证了该计算方法的正确性。     

工艺参数对45钢大电流电接触表面淬火的影响

以45钢为试验材料,研究工艺参数对45钢大电流电接触表面淬火的影响。观察分析淬火层的金相组织,并测量其厚度和硬度分布。结果表明,电接触表面淬火后的淬火层由硬化区和过渡区组成,硬化区为均匀细小的条状马氏体,过渡区为马氏体、珠光体和铁素体的混合组织。工作电流I=17kA、接触压力F=600～800N、工件转速Vr=0.5～0.75r/min时,淬火层厚度为0.78mm,硬化区硬度可达780HV0.1左右。当电参数一定,其他工艺参数改变时,工件表面硬度与淬火层厚度基本不受影响。但经过新型电接触表面淬火处理后,工件表面粗糙度降低,由Ra1.412μm下降至Ra0.732μm。     

40Cr钢表面激光淬火的工艺研究

研究了40Cr钢表面激光淬火工艺参数与硬化层尺寸以及显微硬度的关系,分析了激光硬化层的显微组织。研究表明:选择合适的工艺参数,可使硬化层的显微硬度显著提高,该工艺为40Cr钢表面淬火提供了一条新途径。     

一种风电偏航轴承的热处理工艺调试方法

为了提高风电偏航轴承沟道性能,延长轴承的使用寿命,需要通过工艺试验得到最佳热处理工艺。本文介绍了某风电偏航轴承沟道淬火技术要求,采用中频感应加热表面淬火加低温回火的热处理工艺,分别选用三种不同的工艺参数进行工艺试验,将每种工艺试验结果制备试样并进行金相检测和硬度分析,由试验结果得出符合要求的最佳工艺参数。     

焊后热处理对F12钢焊接组织和性能的影响

对Ｆ１２钢焊缝显微组织和硬度回火时间的变化进行了研究，选择出该钢焊后热处理的较好的工艺参数。     

拉丝机塔轮制造中淬火工艺分析

塔轮是湿型水箱拉丝机中的关键部件。原用45钢生产,采用整体加热的常规淬火工艺,因受工件形状复杂,尺寸效应的影响,硬度只能达到40HRC左右,不能满足槽部表面淬火45～50HRC的设计要求。为此,改删了40Cr钢制造,以朋获得较高的硬度和较好的耐磨性,下面对该塔轮在改用40Cr钢后的工艺等方面进行分析介绍。     

钢的大功率感应加热淬火超硬化

采用自制的微机控制大功率感应加热系统对45、40Cr、GCr15和T10A钢实施表面淬火。试样表面获得超高硬度,高的表面残余压力应力。优化工艺参数,得到上述四种钢最佳淬火工艺规范。试样的回火特性及显微组织结构特点表明,“有效晶粒”超细化是超硬化的主要原因。高密度亚结构和高幅值残余应力对超硬化起附加作用。     

15MnVN代替15MnMoVNRe提高屈服强度和表面淬火硬度的研究

本文采用与工件等效截面的试样，利用１５ＭｎＶＮ钢，经调质和表面淬火后，成功地代替了１５ＭｎＭｏＶＮＲｅ钢，其屈服强度达到了Ｑ／ＣＧ０５－８０《低合金高强度结构钢技术条件》中ＱＪ６０的要求，表面淬火后硬度达到４０－４５ＨＲＣ，有效硬化层深度达到３．８ｍｍ，为１５ＭｎＶＮ钢的使用开辟了一条新途径。经采用试样的工艺方法，三种斗刃的热处理亦获得了满意的结果。     

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。     

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....     

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.