开式整体叶盘通道侧铣粗加工技术的研究

整体叶盘从锻造毛坯到最终零件加工成型,需要切除大量的多余材料。本文提出了一种开式整体叶盘通道区域五坐标粗加工刀具轨迹规划方法。该方法通过生成整体叶盘薄壁叶片的直纹包络面,以确定叶盘通道粗加工区域的边界轮廓;基于直纹面五轴侧铣加工刀具轨迹双点偏置生成方式,利用投影法规划开式整体叶盘通道区域粗铣加工的刀心点轨迹与刀轴矢量方向。加工实践表明,开式整体叶盘的粗加工效率提高30%以上,同时,显著优化了后续半精加工和精加工工序的环境。     

开式整体叶盘四坐标侧铣开槽粗加工轨迹规划

为了提高开式整体叶盘的粗加工稳定性，在粗加工阶段，提出采用将自由曲面蜕变为直纹面的方式简化开式整体叶盘通道开槽加工的难度，实现稳定切削。讨论了直纹面逼近自由曲面的算法，提出了一种新的刀轴矢量计算方法，并基于直纹面给出了开式整体叶片通道四坐标侧铣粗加工数控编程方法，规划出了无干涉的刀位轨迹。实例验证表明，采用该方法可快速有效地实现开式整体叶盘的开槽粗加工，并可提高开式整体叶盘加工中的稳定性。     

整体叶盘复合铣削机床设计

通过盘铣、插铣实验,验证了盘铣应用于整体叶盘加工的可行性,在此基础上提出整体叶盘复合铣加工工艺,将盘铣、插铣、侧铣集成于一台机床上,盘铣用于开槽粗加工、插铣用于曲面成形、侧铣用于除棱清根,实现一次装夹完成整体叶盘的粗加工、半精加工、精加工。以某发动机一级风扇盘开槽粗加工为例,通过UG仿真复合铣、插铣+侧铣、侧铣三种工艺过程,计算出三种工艺的加工时间,计算结果表明复合铣工艺的加工效率是插铣+侧铣的2倍,是侧铣工艺的10倍左右,验证了复合铣工艺的高效性。基于复合铣工艺思想,设计了复合铣机床的整体结构,由高刚性、大扭矩的盘铣、插铣主轴系统实现整体叶盘的复合铣加工,以满足加工的要求。     

整体叶盘通道去余量线切割加工技术研究

整体叶盘的加工余量主要是在其通道开槽粗加工阶段去除的,合理选取整体叶盘粗加工通道余量去除方法是降低通道加工费用、实现整体叶盘加工经济性的关键。由于线切割机床加工单位成本低的原因,采用线切割加工方法对整体叶盘通道进行去余量加工。提出利用叶型与轮毂偏置面确定通道加工边界;通过比较通道边界投影后的投影面积大小确定最优矢量;然后根据最优矢量确定线切割丝与叶盘端面之间的夹角以及切割区域,实现整体叶盘粗加工阶段去除余量最大化。该方法可以有效地解决整体叶盘粗加工阶段经济性问题。试验表明,线切割加工可以应用在整体叶盘通道去余量加工中,并且与传统数控铣削相比,单个通道的加工费用仅为数控铣削加工费用的1/20。     

整体叶轮五轴数控插铣加工刀位轨迹生成算法研究

为了提高整体叶轮粗加工效率和质量,提出了一种整体叶轮五轴插铣加工刀位轨迹的计算方法。根据整体叶轮的几何特征和插铣特点,定义与叶轮轴线垂直的截平面族,构造截平面与叶片型面交线的单侧包络直线族,作为边界面加工刀位,在边界面刀位之间插值,得到整个流道的插铣加工刀位轨迹。运用UG/Open API开发了整体叶轮插铣加工软件模块,最后通过实例验证了所提出的方法是有效的。     

直纹面叶轮插铣加工关键技术

为提高整体叶轮的粗加工效率,弥补目前商用计算机辅助制造软件在五坐标插铣加工能力方面的不足,研究了直纹面叶轮五坐标插铣加工的关键技术。根据直纹面叶片的偏移边界矢量,利用四元数插值方法计算插铣加工的刀轴矢量,提出并推导了五坐标插铣加工的行距和步距计算公式,保证了插铣加工的材料去除率和加工效率。依据上述算法自主开发了整体叶轮五坐标插铣加工专用计算机辅助制造软件,并对该软件生成的刀具轨迹进行了仿真和实际加工验证。结果证明,该方法在一定程度上提高了叶轮零件的粗加工效率。     

基于插铣加工的非等参数刀具轨迹生成方法

针对复杂多曲面通道的多坐标数控粗加工,提出了一种新的刀具轨迹生成算法.该算法以传统的插铣加工方法为基础,提出适合于复杂多曲面通道的新插铣方法;利用曲面参数线,使用B样务曲线正算反算方法,在流道划分的多个截面上做由初始孔到截面轮廓的渐变曲线;通过计算满足残留高度的走刀行距,在各个截面的渐变曲线上提取参数点并拟合出相应曲线,进而得到刀具接触点轨迹.     

钛合金插铣加工切削力试验及工艺参数优化

钛合金整体叶盘结构复杂,制造难度大。应用插铣技术加工整体叶盘能够有效解决上述问题,插铣工艺参数的优化对发挥插铣加工优势具有重要作用。通过插铣钛合金试验研究,探讨工艺参数对切削力的影响规律;根据试验数据建立切削力预测模型,并对模型进行检验;最后以切削力与金属去除率为目标,基于MATLAB进行工艺参数优化,可为钛合金整体叶盘高效切削提供理论参考及技术支持。     

型腔转角插铣粗加工方法

插铣是一种高效的粗加工方法。根据型腔转角面的几何特性,提出了无干涉插铣刀轴方向的算法;根据转角面几何信息和前一把加工刀具参数信息,实现插铣加工区域计算。在两者基础上,提出型腔转角插铣加工的刀位轨迹计算方法。此类方法适合各类型腔的转角粗加工。     

钛合金整体结构件高效插铣工艺实验研究

针对钛合金整体结构件粗加工的插铣和侧铣工艺,从切削力、切削稳定性、切削温度等方面进行了切削实验和分析对比。实验结果表明,在相同切除率条件下,插铣的轴向切削力略大于侧铣的轴向切削力,而插铣作用力仅为侧铣的1/3%;随着切削深度的增加,插铣刀具的振动比侧铣刀具的振动小,且切削过程稳定;
插铣的切削温度要比侧铣的切削温度低。最后,以TC4钛合金整体叶盘通道开槽为例,进行了插铣验证。验证结果表明,插铣切削过程稳定,效率比侧铣提高了近1倍,刀具成本仅为侧铣的13%。     

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.     

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.