新型复合走丝线切割机床的恒张力机构研究

介绍了新型电火花线切割走丝方式,即电极丝做往复低速直线运动的同时还绕自身轴线高速旋转的复合走丝方式的实现方法。通过分析高速走丝电火花线切割机床的张力控制机构存在的缺点,提出两种新型复合走丝电火花线切割机床的张力控制机构,即分别采用惯性力与电磁力实现对电极丝张力控制的装置。阐述了两种张力装置的结构和工作原理,该装置能够克服人工操作张紧轮或重锤式张力机构的缺点,实现张力的自动调节。     

立式旋转单向走丝电火花线切割机走丝系统的设计

基于旋转电火花线切割的加工机理,提出了一种新型的电火花线切割机床结构形式一立式旋转单向走丝电火花线切割机.阐述了一种能同时实现电极丝高速旋转和单向直线运动的新型走丝机构,该机构采用闭环反馈控制拉、放丝的速度差来实现对电极丝的张力控制,详细介绍了机械装置和张力控制的工作原理,并分析了关键机构的运行参数.     

快走丝线切割机床电极丝恒张力机构的实验研究

设计制造了一种重力式电极丝恒张力机构,结构简单,确保加工过程中电极丝张力与张力机构所产生的重力之间具有恒定关系,从而实现电极丝的恒张力控制。一定范围内提高电极丝的张力有利于提高快走丝电火花线切割加工的精度、效率和表面质量。     

快走丝线切割电极丝磨损分析及解决措施

针对线切割加工中非正常磨损和断丝现象,介绍了线切割加工的原理和线切割加工中影响电极丝使用寿命的主要因素。通过采取电极丝的选材,保证运丝机构精度,合理选择电参数,确保冷却系统工作稳定等有效途径来提高线切割电极丝的使用寿命,有利于保证线切割加工的工件质量、提高加工效率和机床的使用经济性。     

新型电极丝恒张力控制系统的研究

在高速走丝线切割机上，储丝筒正反向循环时放电区电极丝张力是否一致，直接影响线切割机的加工质量。为此，研究了一种新型电极丝恒张力控制系统，能够很好地解决电极丝张力的测量和储丝筒正反向循环时放电区电极丝张力一致的控制问题。     

模具线切割精密加工电极丝的应用分析

模具数控线切割加工电极丝的定位是加工程序的起始位置,整个切割图形相对于模具件的位置正确性完全取决于电极丝的严格定位。CTW机床的走丝机构采用十字滑板,U、V轴移动并具有独特的四连杆技术实现锥度加工。通过电极丝位置调整方法、电极丝的选择、线切割加工前的工艺准备及常见断丝、抖丝故障的介绍,目的是为了更好地使用快走丝电火花线切割机床来加工复杂模具精密零件。     

电极丝张力仪

在线切割机床上,电极丝张力的大小,对电火花战切割加工的精度与效率有着直接的影响。张力越小.加工精度与效率越低;张力越大,加工精度与效率都高,但是,张力过大电极丝容易拉断.因此,必须将电极丝的张力控制在—个适当的范围内,而现有电火花线切割机床的张力不能测定,为此,日本 SHIMPO公司新近开发了一种张力仪,可以直接安装在现有的电火花线切割机床上,专门用来测量电火花线切割机.摩上电极丝的张力,以便于最大限度地发挥电火花线如割机床的性能,为模具加工的高效化和高精度化提供方便.     

基于多轴运动控制器的电极丝恒张力控制系统

为解决往复走丝电火花线切割加工空间复杂曲面中电极丝张力变化影响加工精度的问题,分析了张力变化的原因及其对加工精度的影响,介绍了现有电极丝恒张力机构的不足,提出了基于功能强大的可编程多轴运动控制器的电极丝恒张力控制系统,给出了完整的系统软硬件结构.该系统可对线切割加工过程进行随动响应,保持电极丝张力恒定,改善电极丝动态定位精度.进行了恒张力线切割加工对比试验.实际测量结果表明该控制系统的加工误差明显减小,验证了恒张力控制系统的有效性.     

电火花线切割加工工艺特点分析

线切割加工是电火花线切割加工的简称,它是用线状电极(钼丝或钨丝)靠电火花放电来对工件进行切割。线切割机床通常分为两类:快走丝和慢走丝。前者     

线切割加工条件对模具零件表面粗糙度的影响

为改善快走丝电火花线切割加工的表面粗糙度,提高模具加工的质量和使用寿命,分析了快走丝电火花线切割加工条件中放电参数、工作液和电极丝对零件表面粗糙度的影响,并在此基础上提出了改善零件表面粗糙度的相应措施和方法。     

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.     

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.