718H的脉冲电化学复合光整加工工艺试验研究

以模具钢718H为对象,在正交试验的基础上,分析脉冲峰值电压、脉冲频率、脉冲占空比和光整时间对光整加工质量的影响,获得优化的工艺参数.试验表明,试件的表面粗糙度从Ra1.0μm降到Ra0.08μm.     

一种液粒两相流光整工艺与试验研究

参考液粒两相流动中金属降低冲蚀磨损原理,同时结合桨叶式搅拌机搅拌原理,提出了一种液粒两相孔表面光整加工新工艺,分析了加工机理;运用FLUENT软件对流体运动进行仿真;在制备液粒两相混合液的基础上,进行了验证性实验,45钢孔表面经过20 min光整加工后,表面粗糙度Ra值由10.001μm降低到2.173μm。研究结果对后续最优工艺参数确定有指导意义。     

基于磁力研磨法光整内环槽的实验研究

液压系统中常常需要大量内环槽密封结构件,由于尺寸小、加工空间有限,传统研磨工艺难以有效对其表面进行光整加工。结合磁力研磨法的原理及特点提出采用该方法对工件内环槽表面进行实验加工,并总结了内环槽磁力研磨光整的基本工艺参数,经过60 min研磨加工后,内环槽两侧面平均表面粗糙度可由Ra3.47μm降至Ra0.63μm,底面的粗糙度也可由Ra3.25μm降至Ra0.70μm,且通过微观表面观察发现原始加工纹理得到了有效去除。结果表明,基于磁力研磨法,采用磁石直接吸附磁性磨料,与内环槽各个表面均保持1 mm间隙进行光整时,可以实现对内环槽3个面的同步光整加工。     

航空弧齿锥齿轮光整加工理论分析及实验研究

滚磨光整加工是一种新型的微加工技术,能够去除材料表面的痕迹,降低齿面粗糙度,降低齿轮的啮合噪声。采用平行主轴式滚磨光整工艺对某航空弧齿锥齿轮进行光整加工实验研究,阐述了该光整工艺的加工机理,研究了光整磨料与齿轮表面间的相对运动情况;根据齿轮外圆处磨料的切削公式,分析了各因素的影响规律。结果表明,该滚磨光整加工工艺可以显著降低弧齿锥齿轮表面粗糙度,锥轴齿面粗糙度Ra值从0.8μm降至0.4μm左右,锥盘粗糙度值Ra从0.8μm降至0.3μm左右,齿面纹理的一致性明显提高。为后续分析弧齿锥齿轮的振动和噪声特性奠定了基础。     

电化学光整加工中表面毛化的应用

基于对电化学光整加工之后表面微观几何形貌变化的分析,认为“高原”型表面微观几何形貌的存在对电化学光整加工的整平能力及其效果的提高有一定的影响,提出将表面毛化技术应用于电化学光整加工的设想,并实验验证了适度的表面毛化对光整加工是有利的;同时将此方法应用于无缝碳钢钢管内孔的表面光整加工中,在表面粗糙度Ra达0.2μm以下的同时,生产效率也得到提高。     

大面积混粉电火花镜面加工技术的实验研究

对大面积条件下的混粉电火花镜面加工技术进行研究表明 ,加工时间、放电参数及电极表面状态都对加工表面粗糙度有一定的影响 ,通过采用合理的工艺参数 ,大面积下的混粉电火花加工表面粗糙度可达Ra0 .15μm ,所加工的三维型腔表面光亮、均匀 ,呈镜面反光效果     

成型阴极脉冲电化学光整加工在轧辊上的应用

采用成型阴极对冷轧丝杠轧辊进行脉冲电化学光整加工.文章介绍了该方法的基本原理,给出了实验装置,在一定的工艺条件下,对轧辊进行了脉冲电化学光整加工.结果表明,该方法能将轧辊表面粗糙度从0.3μm减小至0.06μm.     

基于响应曲面法的SKD11材料电火花线切割电参数优化

针对SKD11材料的难加工性,利用响应曲面法,采用中心复合设计加工试验,研究电火花线切割电参数对被加工材料表面粗糙度的影响规律,建立二阶响应曲面模型,以最小表面粗糙度为目标优化电参数。研究表明,获得最小表面粗糙度的最佳电火花线切割电参数组合为:脉冲放电时间为13.53μs,脉冲间隙时间为20.11μs,电流峰值为3 A,伺服电压为3.17 V。通过试验验证,被加工材料表面粗糙度为Ra1.997μm,到达了预期效果。     

成形阴极脉冲电化学光整加工技术应用研究

针对将成形阴极脉冲电化学光整加工新工艺应用于V形槽工件的表面光整加工,讨论了影响实际应用中的流场、间隙、电场等关键技术问题及其解决方案.并以实际V形槽工件为例,进行脉冲电化学光整加工,得到了良好效果.实验证明,该工艺应用于V形槽表面的光整加工是成功的.     

齿轮的脉冲电化学光整加工数控分度系统设计

根据成型阴极脉冲电化学齿轮表面光整加工原理,设计了工装和分度数控系统。针对该系统的特点进行了误差分析,提出误差补偿措施。在此控制系统和优化的工艺参数下,采用宽度为5 mm的工具阴极,可在5 min内把模数3、齿数33、齿宽15 mm和齿面硬度HRC50~HRC55的直齿轮齿面粗糙度Ra值从1.6μm降至0.1μm以下,齿面的表面反射率ρ(λ)由30%提高到80%~90%。     

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.     

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....     

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.