可有效降低表面残留高度的新型环形刀具设计

针对工厂实际加工编程时用环形刀进行大切深加工造成的加工后表面残留高度过大且不均,在初次荒加工后需要建立残留模型进行二次荒加工的情况,对环形刀的R角刃形进行优化设计,设计出一种有效降低被加工工件表面残高的大切深高效铣削刀具。以D20R1.5的环形刀为例,理论上该新型刀具比原环形刀加工后的表面残高降低了2.54倍。     

斜圆柱结构的新型微细球端铣刀的设计与制造

针对微细切削刀具的特点与应用需求,设计一种斜圆柱结构的新型微细球端铣刀,将铣刀球端刀刃复杂的空间曲线转化为易加工的平面曲线。根据所设计铣刀的几何结构特征,从制造工艺方面进行刀具结构的调整,分析刀具的刃磨成形原理,并在微细刀具数控刃磨机上完成该刀具的制作。通过与传统螺旋槽球端铣刀和椭圆柱刃型球端铣刀的切削性能对比试验,研究所设计刀具的切削性能。试验结果表明,所设计的微细球端立铣刀在显著降低刀具制备难度的同时,具有较高的切削刃强度,能够满足硬脆性材料的微细切削要求。     

钝圆半径对镍基高温合金的铣削性能影响

铣削典型的难加工材料镍基高温合金时,刀具刃口直接接触参与切削,对铣削性能起到决定性作用.通过建立刀具精确三维模型和有限元切削仿真模型,对不同钝圆半径的圆角铣刀铣削镍基合金进行仿真,分析钝圆半径对切削性能的影响,开展切削试验进行验证.结果 表明:钝圆半径对刃口附近集中区域的应力和温度以及进给抗力和切深抗力影响较为显著;钝...     

用金刚石端铣刀高速加工铝材

试验用设计的金刚石端铣刀进行了铝合金铣削试验,在常规的切削速度下用普通刀具加工零件,由于积屑瘤和毛刺的形成,往往引起刀具寿命短,加工表面质量差及切削刃质量差.在许多行业的铝合金加工技术中,较高的表面光洁度及切削刃质量很重要,也很需要.本试验的结果揭示出使用新设计的金刚石端铣刀高速切削铝合金,能加工出镜面表面,而不产生积屑瘤和毛刺.     

椭球头铣刀设计及其刀具路径生成算法

随着航空航天、汽车模具等领域内型面复杂程度的日益增大,目前对不同形状、不同性能刀具的需求也不断增加。设计了一种刀具端部切削刃所在回转面为椭球面的整体铣刀,以下称为椭球头铣刀。建立了椭球头铣刀参数化模型,为刀具的参数化设计提供理论基础。提出了椭球头铣刀的三种切削刃曲线模型:等螺旋角切削刃、正交螺旋形切削刃和新型切削刃,精准的刀具切削刃曲线模型为椭球头铣刀的精准制造提供了理论依据。提出了椭球头铣刀三轴端铣加工曲面的刀具路径生成算法,并通过试验验证了刀具路径生成算法的正确性和可行性,分析了刀具的切削性能并验证了椭球头铣刀的优势,为椭球头铣刀的推广应用提供了理论基础。对椭球头铣刀的参数化设计和应用研究,也为其他新型刀具的设计和应用提供了方法和理论依据。     

基于ADAMS的端铣齿轮动力学特性研究

采用端铣加工方法加工渐开线齿轮,运用UG软件对某大模数齿轮轴进行刀具轨迹仿真,并通过数据转换将齿轮和刀具模型导入动力学仿真软件ADAMS中。在ADAMS中建立刀具齿轮铣削系统仿真模型,对端铣刀粗加工切削过程进行动力学分析,得到刀具和工件的位移、速度及加速度变化曲线以及主轴转速和进给速度对切削加工及振动影响的变化规律,为实现端铣齿轮加工技术的实际应用提供参考。     

自滚切端铣刀

刀具是金属切削加工的重要工具之一。它对发挥机床性能、提高生产率、保证加工质量、降低加工成本都有很大作用。特别是新型刀具的出现,常常把劳动生产率和加工质量提高到一个新的水平,同时也促进机床的相应改革和发展。根据国内外机械工业发展形势和刀具的发展动向,综合分析了大直径刀盘、阶梯铣削和滚切刀具的特点,我们设计了自滚切端铣刀,进行了初步试验,效果良好。     

多轴铣削加工表面形貌建模与仿真研究分析

在考虑刀具偏心的情况下,建立多轴铣削加工形貌仿真模型,推导出多轴铣削情况下球头铣刀切削刃上任意一点相对被加工工件的轨迹方程,建立仿真算法求解被加工工件表面残留高度,并对平面铣削加工以及圆弧面铣削加工分别进行铣削仿真研究,研究刀具轴线角、进给倾角分别对表面粗糙度的影响。通过提高铣削过程中被加工工件表面质量,为开发实用的铣削加工过程物理仿真系统奠定了坚实的基础,对发展数控加工技术和指导实际生产具有一定的意义。     

冷泵低温刀具系统

冷泵低温刀具是一种新型刀具,它是把刀体致冷,使刀具在低温状态下进行切削加工。该刀具是为了解决一种难加工材料的切削加工而设计的,生产试验表明,其耐用度与普通刀具相比提高3～4倍;表面粗糙度从Ra12.5μm降低到Ra5μm;铁屑卷曲半径减小,易碎断;不用冷却润滑。该刀具适用于各种材料的切削加工,特别是切削难加工材料,经济效益显著。     

自滚切端铣刀

本文论述了自滚切端铣刀的基本原理和结构类型，以及与普通刀具切削过程的本质区别。试验研究和实际应用证明自滚切端铣刀具有耐用度高，加工表面质量好，生产效率高等优点     

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...     

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.     

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.     

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.