WEDM电极丝恒张力微机控制系统研究

电火花线切割机电极丝张力的大小,对加工精度和加工表面质量有着重要影响.设计了一种恒张力控制系统,采用ER阻尼嚣为执行元件,以微机作为控制处理核心,系统响应速度快,较好地解决了张力测量和控制精度问题,实现了电极丝的恒张力控制.     

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。     

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。     

基于改进型粒子群PID算法线切割电极丝恒张紧力控制系统

在慢走丝线切割走丝系统中,电极丝容易受到外界干扰和自身控制系统影响下,电极丝的张紧力会发生一定程度的波动,最大波动幅值可达50%,将导致导轮之间电极丝发生较大的挠曲变形和振动,严重影响加工工件的形位精度和表面质量。对电极丝进行受力分析,介绍改进型闭环控制电极丝走丝系统,设计恒张紧力闭环控制系统,运用改进型粒子群PID算法对电极丝进行在线恒张紧力控制。实验结果表明:本次设计的控制系统,具有高精度和实时性,电极丝张紧力波动控制在5%之内,对外界冲击载荷的修正时间约为4 s,且电极丝横向振动减少接近50%。     

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.     

大厚度复杂曲面线切割丝损在线检测及补偿

针对在高速走丝电火花线切割机床上利用附加三轴联动装置加工大厚度三导线空间曲面中电极丝损耗影响加工精度的问题,分析导致电极丝损耗的主要因素以及对加工精度的影响并设计电极丝损耗变化在线检测装置.通过引入补偿因子,对数控模型进行了改进,提出了包含实时补偿量的数控算法.建立基于可编程多轴运动控制器(Programmable multi-axis motion controller,PMAC)的运动程序实时补偿预处理模块,给出实时加工补偿实例,进行线切割加工对比试验,试验结果表明,电极丝损耗对加工精度影响大幅减少,较好地消除了丝径变小对加工精度的不利影响,验证了电极丝损耗检测及在线补偿模块的有效性,也为二维高精度、大厚度、大行程工件线切割加工提高加工效率,节省原材料,充分利用电极丝提供了有力支持.     

基于ER阻尼的WEDM电极丝恒张力微机控制

电流变液是一种可控智能阻尼介质,其表观粘度和剪切屈服应力随外加电场发生快速变化。设计了一种以ER阻尼器为执行元件的恒张力微机控制系统,系统响应快,较好地解决了电火花线切割加工过程中的张力测量和控制精度问题,实现了电极丝的恒张力控制。     

线电极磨削系统电极丝恒张力模糊控制研究

针对自主设计的一种新型WEDG系统走丝机构,提出了采用模糊控制的方法实现电极丝的恒张力控制.首先分析了该新型WEDG系统走丝机构的工作原理,建立了系统的走丝机构控制模型.在此基础上,基于模糊控制理论,根据张力反馈对送丝轮的转速进行闭环控制,最终实现了电极丝的恒张力控制.基于该WEDG系统进行了微小工具电极的加工实验.结果表明,该WEDG系统走丝稳定、张力恒定,能够以很高的效率制作出直径小(直径小于10 μm)、几乎没有锥度的工具电极,很好地满足了的微细电火花加工机床微小工具电极的制作需要.     

数控线切割机床快速走丝系统的恒张力控制

目前,我国生产的数控线切割机床大多数是采用高速走丝系统,电极丝是反复使用的。其内在张力无法进行调节与控制。工作一段时间后,电极丝会产生,伸长现象,从而使其张力减小,引起电极丝抖动,直接影响工件的加工精度和表面粗糙度。本文提出一种能使电极丝张力维持恒定的装置。其结构简单、成本低、便于推广使用。它是在阻转情况下工作的,只要电极丝一有松动,电机立刻转动,产生恒拉力。经过钢丝绳13使紧丝滑块8向下移动,拉紧电极丝,使丝内的张力维持恒值。具体的张力数值应通过切割工艺试验,调节电压来达到。对于不同直径的电极丝,所需维持的张…     

往复走丝线切割电极丝精确定位方法及系统开发

电火花线切割加工精度取决于其定位精度和定形精度,而定位精度主要取决于线切割中电极丝的定位精度。分析影响电极丝位置精度的因素:丝杠等机械系统的传动精度、电极丝与工件的位置精度和电极丝的垂直度等。提出了"矩阵化"补偿方法和智能接触感知方法,开发了精确移轴、碰边、对中和校垂直等定位模块。该方法应用于往复走丝线切割数控系统,提高了电火花线切割加工的精度。     

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。     

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.     

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....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.