基于3D打印技术的离心泵叶轮快速精铸工艺研究

以具有典型复杂型面的离心泵叶轮为应用范例,开展了基于3D打印技术的快速精铸工艺研究。首先基于Pro/E软件建立离心泵叶轮三维模型并进行CAD优化设计,基于RPData软件对叶轮模型进行前处理,然后通过3D打印机制作叶轮树脂模型并进行后处理,最后以叶轮树脂模型作为熔模进行熔模精密铸造,最终得到离心泵叶轮精密金属零件。经测量知制得的叶轮铸件的尺寸精度可达CT4级,表面粗糙度可达Ra6.3um以下。     

基于ProCAST及3D打印技术的闭式叶轮快速铸造技术研究

针对单件小批量复杂形状零件快速制造问题,以具有复杂内部空腔结构的闭式离心泵叶轮为研究对象,开展了基于Pro CAST及3D打印技术的快速铸造技术研究。首先采用Pro/E软件建立了离心泵叶轮及其浇注系统整体数学模型,通过Pro CAST软件对该叶轮铸造工艺过程进行了数值模拟仿真,然后完成了闭式叶轮及其浇注系统整体树脂模型的3D打印,并以该树脂模型作为熔模进行了熔模精密铸造,最终制得了闭式离心泵叶轮铸件。研究结果表明,利用该快速铸造技术制得的闭式叶轮铸件的尺寸精度可达CT4级,表面粗糙度可达Ra6.3μm以下。     

3D打印技术和铸造技术的融合应用与展望

3D打印技术与铸造技术相融合将发挥不可估量的作用。3D打印的蜡模、光敏树脂模、塑料、砂型、砂芯、金属等能用于失蜡蜡模、模具、铸型、型芯、复杂内腔镶件等铸造元素,这些元素可与熔模精密铸造、石膏型铸造、砂型铸造、低压（差压）铸造、双金属复合铸造等几乎所有的铸造方法融合,制造各种金属合金构件。融合解决了3D打印材料和成本的问题,突破了只能先模具后铸造的瓶颈,加速了铸造行业的发展,为快速发展个性化创新工厂、制造业升级提供了可能。     

基于3D打印技术的主泵试验用叶轮研制

为提高核电站主泵性能试验用缩比叶轮的制造质量,缩短制造周期,开展了利用金属3D打印技术进行试验叶轮制造的研究。基于叶轮结构和不同3D打印成形工艺的特点,选择SLM技术作为主泵试验用叶轮的3D打印方案,完成主泵试验用叶轮3D打印模型的设计及成形技术参数的设置,经过试验验证确定主泵试验叶轮的金属3D打印成形工艺,并成功打印出316L材料的主泵试验用缩比叶轮。结果表明,利用金属3D打印技术制造的叶轮,其产品质量及力学性能指标满足试验用叶轮的设计要求,有效缩短了制造周期。     

光固化3D打印关键技术研究

针对单件批量复杂形状产品的快速制造问题,以具有典型复杂形状的离心泵叶轮为研究对象,开展了基于光固化快速成型技术的3D打印关键技术研究,研究内容主要包括:模型CAD优化设计技术、前处理技术、成形工艺参数设计、光固化原型后处理技术。该研究结果可为后续开展3D打印应用技术研究提供坚实的理论基础。     

金属3D打印技术的应用与发展前景

3D打印技术属于快速成形技术,区别于传统的减材制造,3D打印技术称为增材制造技术。传统零件的制造一般需要刀具和模具,且很难加工于形状复杂、表面不平整的零件。而3D打印技术是借助计算机、激光和数控等现代手段,在电脑里面建立好要加工零件的3D模型文件,模型建立完成后将其导入到切片软件中,设置加工参数,例如加工速度、层高等,设置完成后再将其导入到3D打印机中,打印机拾取加工参数并通过对材料进行逐层打印的方式来实现物体的加工。普通3D打印技术应用的材料一般为树脂、PLA、ABS塑料等,而金属3D打印技术的材料为金属或者合金材料。依据金属3D打印工艺的不同,可大致分为选择性激光烧结技术（SLS）、选择性激光熔化技术（SLM）、电子束选区熔化技术（EBSM）、激光近净成形技术（LENS）、直接金属激光烧结技术（DMLS）以及其他新技术等。金属3D打印技术以其能实现任意形状零件的加工的特点从而在精密制造,航空航天、医疗器械等众多领域得到了广泛应用。     

基于叶轮的逆向工程及快速成形在实训教学中的应用

本文以叶轮零件设计为例,通过叶轮的"结构分析→扫描→3D建模→3D打印"来研究探讨逆向工程在实训课程中的应用。实训内容包括四步:1.用3D扫描仪对叶轮的表面进行扫描,获得表面的点云数据;2.将点云数据导入三维建模软件Solidworks进行建模;3.对建立的模型进行优化,为3D打印做准备;4.将优化后的模型导入快速成形机的软件中,进行分层打印。     

3D打印快速制造技术推动铸造行业 革命性发展

正3D打印技术作为一种增材制造技术,逐渐被大家认知并广泛应用。3D打印突破了先模具再生产的制造模式,直接生产熔模精密铸造蜡模,普通砂铸用砂型、砂芯和金属型等工艺用复杂砂芯,同时也可以直接打印成金属件。众多3D打印直接或间接成型金属零件方法中,3D打印技术与传统铸造业相融合,快速制造低成本铸件,倍受制造业关注。本文介绍几种工业级3D打印和快速制造金属的方法,解     

3D扫描检测技术在MP泵质量控制中的应用

离心泵叶轮的制造精度会直接影响性能,使用Faroscanner激光3D扫描仪对离心泵叶轮进行扫描,运用QUALIFY将扫描点云与三维模型进行对比分析,分别对叶轮流道宽定歌叶片曲面形状、各处壁厚进行了误差分析,根据分析结果,对模具进行修正,使离心泵的效率提高3％,同时产品性能的一致性得到有效控制。     

基于三维扫描和3D打印的鼻套模具制作关键技术

为解决喷火表演鼻子容易烧伤的问题,运用三维扫描技术进行反求设计,并用3D打印方法制造。首先,使用三维扫描仪获得鼻子部位扫描曲面,运用Meshmixer软件对曲面处理得到鼻子三维数字模型;其次,绘制鼻套设计所需三维模型并与鼻子三维模型进行布尔运算,得到鼻套模具三维模型,将模型数据导出为切片软件可识别的STL文件;然后,设置熔融沉积成型3D打印机参数、添加外部冷却设备,以聚乙烯醇(PVA)为打印耗材,对鼻套模具进行打印;最后,使用硅胶浇注、热水溶模的方法得到一体成型的鼻套模型。结果表明:该方法能够有效应用于鼻套模型的制作,实现三维扫描曲面壳体到模具实体的转化,为类似产品的制造提供了一种方法。     

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.