双柱立式车床横梁结构轻量化设计研究

机床横梁为现代立柱式机床主要支撑部件,目前的横梁设计存在自身质量过重及横梁刚度有待提升等问题。以DVT250型双柱立式车床为研究对象,预设计不同种类车床横梁结构,研究横梁的受力变形情况与固有频率值;根据车床应用中实际工况进行静力特性分析及模态分析,以横梁质量最小化为目标,根据仿真结果进行相对密度法拓扑优化设计,根据拓扑优化的材料分布结果及生产工艺性确定横梁减质位置,通过分析对比多组(多种类)横梁仿真分析数据后确定菱形筋板结构为最佳横梁筋板结构。优化结果为：车床所用的最优横梁结构减重比为4.81%,受力最大变形降低率为12.62%,静刚度提升了6.52 N/μm;优化后横梁1阶～6阶固有频率分别提升了16.30、22.42、10.83、13.45、26.46和20.48 Hz,前6阶固有频率值均出现不同程度的提高。     

重型数控卧式镗车床整机模态分析与实验研究

重型数控卧式镗车床适用于一些直径和承载均已超出常规机床加工范围的大型轴孔类零件的加工,其加工精度往往受到外界干扰及加工过程颤动的影响。为了有效提高重型数控卧式镗车床加工精度,有必要对其振动特性进行研究。利用UG软件建立重型数控卧式镗车床整机模型,采用ANSYS软件对模型进行模态分析,通过对所得整机前6阶模态固有频率和振型的观察与描述,提出确保机床加工精度的优化方案。最后,结合LMS Test.Lab11b软件平台,采用锤击法模态实验结果与仿真结果进行对比分析,验证了仿真结果的准确性及可靠性,具有一定的工程实际意义。     

基于HyperWorks的机床横梁的拓扑结构优化设计

横梁是机床结构中极重要的承载大件,其性能直接影响对机床的加工质量,同时,也是最具减重潜力的关键件。采用HyperWorks软件,以结构柔顺度最小为目标,对横梁进行基于变密度法拓扑优化。根据优化后的横梁形貌及实际经验对模型进行细节修改,建立横梁最终优化模型。在ALGOR中对横梁仿真分析,结果表明:优化后的横梁较原设计在静、动态特性均有所提高,横梁总重量减少28.34%。     

典型零件——轮毂的工艺方案

1.机床的选型 汽车及摩托车行业的典型零件-轮毂,对于这类零件往往要进行高效、大批量、高精度的加工.为此我厂专门设计出数控轮毂车床,这类车床的主要优点是:设计中对主轴、床身、底座、横梁等部件的刚度进行合理匹配,大大提高了整机的刚性,确保了高速运转时的稳定性.     

车床尾座故障对零件加工质量的影响分析

车床尾座故障是影响零件加工质量的重要因素之一,探讨分析其对零件加工质量影响对机床维护、精密加工等具有重要意义.在分析车床尾座内锥面磨损、位置偏移等主要故障基础上,探讨了其对零件加工质量的影响关系.     

基于ANSYS Workbench对立式车床横梁的模态分析

立式车床的横梁在机床工作过程中起到对刀架的固定与支撑的作用。针对切削加工中产生的振动对横梁造成的影响及严重影响其加工精度的问题,利用ANSYS Workbench对某型号单立柱立式车床横梁进行模态分析,对提取的前6阶固有频率与与之相对应的振型的变化和加工精度影响进行了分析。     

汽车零件——轮毂的机床选型

1．机床的选型 汽车及摩托车行业的典型零件一轮毂,对于这类零件往往要进行高效、大批量、高精度的加工。为此我厂专门设计出数控轮毂车床,这类车床的主要优点是：设计中对主轴、床身、底座、横梁等部件的刚度进行合理匹配,大大提高了整机的刚性,确保了高速运转时的稳定性。     

微小车床结构设计及动态特性分析

以实现微小细长零件的车削加工为主要研究目标,设计了一种微小车床,通过分析机床微小化带来的关键问题,结合微小车床的特点,提出合理的设计方案,其外形尺寸为400 mm×300 mm×300 mm.同时采用ANSYS软件对电主轴进行了谐响应分析,对微小车床的整体结构进行了动态分析,并建立了机床振动模型,对微小车床的动态特性进行了理论上的探讨.     

基于神经网络和遗传算法的机床床身优化设计研究

机床的床身的动态特性和静刚度直接影响加工精度、生产效率以及机床的使用寿命,目前机床正朝着高速、高精度、复合化以及高自动化的方向发展,因此研究机床床身的动态特性和静刚度十分必要。为提高某机床床身和横梁的动态特性和静刚度,综合运用结构动态优化原理,神经网络和遗传算法,对床身和横梁进行了结构动态特性分析,提出了该床身结构的优化方案。分析结果表明,优化方案的床身和横梁的动态性能和静刚度得到了明显提高。可供相关机床床身优化设计参考。     

采用灰色关联—层次分析法的机床横梁优化设计

机床横梁是机床零部件主要支撑部件,对机床的加工精度影响很大,因此,需要对横梁自身的结构进行优化,以提高机床加工精度。文中首先对原横梁进行仿真分析,并依次分别对横梁薄弱位置的结构、筋板结构、筋板厚度进行了设计与分析,采用灰色关联—层次分析法对不同筋板厚度的横梁进行分析与数据处理,最终获得最优方案。结果表明,横梁"井"型筋板结构设计,上导轨支撑筋板倾斜55°,筋板厚度15mm为最优方案,优化后横梁质量减轻了751kg,形变量减少了3.6%,一阶固有频率增加了3.5%,优化设计效果明显,为机床其它零部件的设计提供了方法参考。     

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.