印刷机高点闭牙机构动力性能改善方法研究

针对印刷机高点闭牙机构在高速时的冲击、噪声问题,给出了高点闭牙机构动力性能分析及改善的一般方法,建立了通用的分析方程;并结合某型号印刷机高点闭牙机构进行了实例分析,揭示了机构的动力性能及存在的缺陷.在此基础上,对此机构进行了动力性能改善,改善后机构的角加速度、接触力、铰支力平稳、无突变,角加速度峰值降低了62%,明显的改善了高点闭牙机构的动力性能.     

固定凸轮的摆动从动件凸轮机构运动特性分析方法

根据固定凸轮的摆动从动件凸轮机构的运动特点,提出了该机构运动特性分析的一般方法,建立了通用的分析方程,并将该方法应用于印刷机的高点闭牙机构的设计中,揭示了该机构的运动性能及存在问题,分析结果与实际情况一致,验证了该方法的正确性及优越性.     

MW1050Ⅱ自动模切机叼纸牙排定位性能优化

为进一步提高MW1050Ⅱ自动模切机的工作速度和精度,对自动模切机的重要机构后靠规定位机构和叼纸牙排的运动规律(位移、速度、加速度)进行了研究,分析了后靠规从动件对叼纸牙排产生冲击的原因,对原后靠规机构从动件运动规律进行了优化设计.优化结果表明后靠规从动件对叼纸牙排产生的冲击、噪声大大减小.     

某特种车转向冲击噪声研究与分析

在某特种车样车试验中,转向行驶时车内出现冲击噪声,严重影响整车NVH特性。首先运用主观评价法判断前驱动转向系统为冲击异响的主要故障区域。而后,通过对前驱动转向系统关键部位进行振动信号采集,并结合声学传递路径分析法,初步确定了冲击噪声的激励源为前桥万向传动机构。运用多体运动学仿真方法,采用ADAMS软件对前桥万向传动机构进行了运动干涉分析,得出前轮转角大于等于19°时,前桥万向传动机构的确存在运动干涉现象,最终确定了冲击噪声的产生的机理,为后续进一步改进提供了可靠依据。     

一种间隙副连杆模型及其在复杂机构精度分析中的应用

由于运动副间隙的存在以及制造误差而导致的精度丧失、冲击、噪声、寿命降低等问题已引起人们的关注,本文利用概率统计概念建立的考虑运动副间隙和杆长误差的“随机杆”机构模型首次应用于分析真空开关复杂机构系统的运动精度问题,研究表明各尺寸参数误差对位移、速度、加速度精度有不同敏感程度,机构输出的位移、速度、加速度对各几何参数的敏感程度不仅与运动位置有关,而且构成机构系统的各构件对输出精度的影响存在较大差异。     

三次样条插值函数在凸轮机构运动分析中的应用

凸轮机构的运动分析在机械优化设计中具有重要的研究价值。本文对目前常用的几种凸轮机构运动分析方法进行了评价,指出了其不足和存在的问题,然后将三次样条函数应用于凸轮机构的运动分析中,建立了基于三次样条函数的凸轮机构运动分析方程,最后以印刷机的开闭牙凸轮机构为例,实现了其完整的运动分析,仿真结果验证了方法的正确性及优越性。     

水下航行器盖板启闭机构动力学分析与优化

为提高水下航行器快速性、减小开孔带来的噪声,盖板启闭机构被广泛应用。以空间连杆机构和凸轮机构为基础设计了盖板启闭机构方案,建立机构运动学模型,以盖板运动特性为设计目标,初步确定凸轮轮廓;建立机构的动力学模型,通过数值仿真分析盖板启闭机构的动力学特性,针对瞬时冲击载荷过大的问题开展方案优化设计。盖板启闭机构经过优化后,工作时对驱动力的要求明显降低,并且工作运行平稳,消除了冲击振动,能有效提高设备的可靠性和隐身性。     

变胞机构构态切换时的冲击问题分析与仿真研究

研究变胞机构在构态切换过程中的冲击问题。根据变胞机构的变胞方式,将构态切换时产生的冲击运动分为静冲击运动和动冲击运动两类。采用Newton-Euler方程分别建立变胞机构的静/动冲击动力学模型,并结合经典碰撞理论和恢复系数方程,推导出构态切换时变胞构件的静/动冲量求解模型。对变胞机构的静/动冲击动力学模型进行等效分析,分别求得变胞运动副处的冲量与静/动冲量之间的函数表达式,并以此为基础,结合树系统内部冲击动力学理论,建立变胞机构非变胞运动副处的冲量求解模型。以平面3自由度变胞机构和平面纸板折叠变胞机构为例,研究机构在构态切换时的冲击问题并进行数值仿真计算,分析不同输入特性和恢复系数对机构冲击运动的影响。所提理论与方法也适用于多体系统内部构件之间冲击问题的研究。     

一回转平台印刷机滚筒版台主传动机构的优化设计

TY401型一回转平台印刷机滚筒与版台主传动机构由双曲柄四杆机构和曲柄连杆机构组合而成。在分析机构运动规律的基础上,通过建立数学模型,探讨了该机构优化设计的途径,并进行了CAD实际计算。为该系列新型印刷机的开发提供了解决方案。     

锡膏印刷机印刷系统的误差分析与补偿

为了减小或消除全自动视觉锡膏印刷机的印刷系统误差,在介绍了锡膏印刷机系统的组成和功能的基础上,通过分析运动机构产生系统误差的原因和作用过程,针对平台运动机构误差做了定量分析,并对平台运动机构进行了误差测试,根据测试得到的结果数据,设计了一种减小印刷系统误差的补偿方案。实验结果表明,对印刷系统的误差测试与分析是合理的,所建立的印刷系统的误差模型准确可靠,对运动精度的分析和实际生产装配有一定的指导意义。     

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.     

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....     

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.     

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.