CFRP/Al叠层结构钻铰锪一体制孔切削力建模与预测技术

针对钻铰锪复合刀具一体制孔过程,构建瞬时切削力模型,为制孔切削力优化、抑制CFRP/Al叠层结构的制孔缺陷提供理论依据。将CFRP/Al叠层结构钻铰锪一体制孔过程拆分为钻削、铰削、锪窝,基于CFRP与Al的细观斜角切削模型,分别建立钻削、铰削、锪窝过程的动态切削力(轴向力与扭矩)模型。根据切削特点及所处切削状态对制孔过程进行阶段划分,利用钻削、铰削以及锪窝的切削力模型,计算出相应阶段的切削力。根据工作前角数学模型,分别建立钻削、铰削、锪窝过程的前角均值、剪切角均值和摩擦角均值的数学模型,并且给出纤维方向角关于时间的变化模型。基于接触力学理论建立横刃的切削力模型,最终形成CFRP/Al叠层结构钻铰锪一体制孔刀具的瞬时切削力的模型。最后,搭建制孔试验平台,进行钻铰锪一体制孔试验,验证瞬时切削力模型的正确性与可靠性。     

锪窝钻的改进设计

通过复杂螺旋面钻尖设计方法导出锪窝钻钻尖内刃后角公式及内刃后角与内刃偏角的关系表达式 ,改进了锪窝钻的设计与制造。生产实践证明 ,改进后锪窝钻的切削性能及使用寿命显著提高。     

特种窝座锪钻

<正> 普通锪钻只能在孔的上端面锪沉孔、倒角或锪平面,而在孔的下端面或在断续孔的间断处锪孔就无能为力了,特种窝座锪钻解决了这个难题。特种窝座锪钻不仅不需要象以往那样:每加工一个零件,刀具在刀杆上     

结合面螺栓孔的反锪窝加工

设计了一种结合面螺栓孔的反锪窝夹具，解决了原有反锪窝工序所存在的问题。     

螺栓孔沉孔平面锪钻的改进

水泵行业由于外筒体、泵体含有较多的螺栓孔,因此螺栓孔沉孔的加工量较大,虽然有多年的加工经验,但平面锪钻工装的消耗比较大,遇到铸钢件、不锈钢件需上镗床加工。因此,工厂提出了对锪钻工装改进的要求。经过对其结构的改进并现场使用取得了很好的效果,改进前后的锪钻见附图。     

新型锪钻

一般加工圆柱沉头孔和锥形沉头孔(图1),有两种工艺方案,1.分两道工序进行,即先用麻花钻钻孔,然后用锪钻锪孔;2.用复合钻加工。第一种工艺方案需要的设备多,加工效率低,单件加工成本高;第二种工艺方案由于刀具制造复杂、周期长、费用高、重磨不易掌握,只适用于大批量生产。近年来,我厂使用图2所示的新型锪钻,加工如1-b)所示的锥形沉头孔,经济效益很好。图2中,锪钻1用螺钉2     

控制沉孔尺寸

在较薄的钣金件上锪图1所示的沉头螺钉窝时,尺寸D往往难以保证,因而影响装配质量。若锪窝偏小,则沉头螺钉头部高出平面;若锪窝偏大,则会使沉头螺钉头部陷入,影响     

复合锪钻的设计与制造

复合锪钻如图1所示。它是一刀多刃加工内孔的刀具。近年来多见于航空、航天和机械工业。复合锪钻是高效率刀具之一。它可以在钻床、卧式车床和自动组合机床上,加工钢、铸铁、有色金属及其合金。它可以加工φ5-φ50mmH8级精度的孔。表面粗糙度值Ra=1．6μm,相对部位的同轴度可达0．01～0．02mm。复合锪钻可作精加工刀具,也可作复合铰刀铰孔前的半精加工刀具。     

加工汽车前桥U型螺栓紧固面优越性分析

重型汽车前桥是汽车的主要部件,其U型螺栓的紧固可靠性非常重要,紧固螺母平面加工工艺性较差,常用标准结构锪钻加工操作繁复、生产效率低,刀具损坏频率高,产品质量得不到保证。本文详细分析了汽车前桥U型螺栓紧固面加工过程中的不同状态,对采用标准结构锪钻加工过程的缺点进行了剖析,介绍了一种与标准锪钻结构不同的新型锪钻结构,其结构简单、使用方便、生产率高,产品精度可有效保证,值得在此类产品加工中推广应用。     

基于PLC的钻锪组合机床控制系统的改造

采用西门子S7-200系列可编程控制器(PLC)对钻锪组合机床的控制系统进行技术改造,介绍了钻锪组合机床的工作过程,给出设计了PLC控制的I/O端子接线图和梯形图程序。实践证明改造后的钻锪组合机床在实际生产中运行稳定,生产效率大大提高。     

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.     

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....     

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.