机械式轴向深孔振动钻削系统的设计

深孔的钻削加工过程中,经常生成带状切屑,堵塞在孔内,对加工质量产生影响,特别是经常发生卡钻或断钻事故。如在钻削过程中,对切屑进行周期性断屑,并与负压抽屑装置配合使用,解决了深孔加工过程中断屑排屑困难的问题。设计一种机械式深孔振动钻削装置,对深孔进行振动钻削,可通过改变电机的转速调整其钻削频率,改变滑块的位置可调整振幅,显著特点是结构简单,振幅与频率调整方便,提高深孔的加工质量。     

电磁式轴向深孔振动钻削装置的设计与分析

深孔的钻削过程中,经常会产生连续的带状切屑,堵塞在孔内,极易划伤已加工表面或者发生卡钻与断钻事故。设计一种电磁式深孔振动钻削装置,可通过改变交流电的频率和大小调整其钻杆频率与振幅,并与负压抽屑装置配合使用,显著特点是结构简单,振幅与频率调整方便,解决了深孔加工过程中断屑排屑困难的问题,提高深孔的加工质量。     

深孔加工轴向振动装置设计

深孔加工在孔加工中占有较大的比重,深孔加工技术的难点之一是连续自动排屑。本文基于振动钻削机理,结合现有轴向振动钻削装置,在此基础上进行改进,设计了一套轴向振动装置。装置中使用压电陶瓷致动器有效地避免了机械传动所产生振动的不稳定性。基于Deform-3D软件对轴向振动钻削进行切屑模拟实验,并通过实验验证了轴向振动钻削较普通钻削而言在断屑方面及孔表面质量方面所具有的优势。     

深孔加工振动断屑装置设计

针对深孔加工过程中切屑形态不稳定所形成的排屑不畅问题,基于振动钻削理论,设计振动断屑装置,有效控制切削形态,保证顺利排屑。通过给刀具施加轴向周期振动,振动断屑装置可实现变切厚钻削和钻头轴向振动,使切屑易断,并在一定程度上提高了表面加工质量。通过实验探究了切屑形态与切削参数的关系,分析了振动断屑装置的最佳工作参数。     

超声轴向振动钻削断屑机理分析与试验研究

基于振动钻削原理对振动断屑机理进行了研究,建立了振动钻削数学模型,并分析了轴向动态切削厚度变化规律及保证断屑时所需的振幅条件。在设计的超声轴向振动钻削试验装置上进行了深小孔超声振动钻削与普通钻削的对比试验。试验结果表明与普通钻削相比,振动钻削加工得到的孔具有较小的扩孔量和较好的断屑、排屑效果。     

深孔振动钻削的断屑条件研究

本文通过建立深孔振动钻削的数学模型,在振动钻削相邻两转间的断屑条件的基础上推导出更为一般的断屑条件式,为振动钻削断屑过程的参数匹配提供了理论依据,并得到了振动钻削加工试验的证明。     

钳工操作中深孔的钻削实践分析与改进

在金属切削加工过程中,钻削深孔一直是个难题,尤其是加工精度难以保证。深孔钻削的关键是解决断屑、排屑问题。从教学角度结合实践操作,针对钻削深孔加工存在的问题,设计了一种新型的内排屑深孔钻头。以钻头的结构和刃磨特点为切入点,结合生产实践进行了振动钻削实验,实现了断屑、排屑的流畅,达到了钻头应具备的良好性能。     

振动深孔钻削

顾名思义,振动深孔钻削就是振动切削技术与深孔钻技术(指枪钻、BTA钻、喷射钻、DF钻等总称)相结合的新型深孔钻削技术。它具有一般深孔钻所无法比拟的优点。振动钻孔,由于断屑好,排屑方便,加工后的孔精度、光洁度高,可提高钻孔效率2～5倍,降低了工人劳动强度,延长了刀具使用寿命。振动深孔钻削特别适用于又韧又粘的难加工材料的钻孔。本文介绍振动钻孔装置和振动切削原理,以及车床如何改装成振动深孔钻床,供参考。     

超细长小直径深孔振动钻削工艺

介绍了一种超细长外排屑深孔振动钻削系统,分析了外排屑DF系统加强排屑的机理,阐述了枪钻的选取与刃磨、钻削用量和振动参数的选取原则。用35CrMo进行了φ5.65×300mm钻削试验,结果表明只要参数选择得当就可以实现可靠断屑,使排屑顺畅,而且孔的精度很高。     

小直径内排屑深孔振动钻削试验与分析

目前,国内外采用振动钻削来加工小直径深孔,但都存在着两类问题：一是振动钻削系统中,多数振动装置的振幅是不可调节的,或凋幅十分困难和麻烦;二是小直径深孔钻头的设计与制造,大部分是采用外排屑枪钻,很少采用内排屑深孔钻。由于小直径枪钻制造工艺上的困难,国内主要采用进口枪钻,价格昂贵,设备要求较高,很难在生产中推广使用。对此我们设计了振幅连续可调、操作简便的振动装置和制造工艺简单的小直径排屑深孔钻,并进行了φ8×300mm和φ6×50Omm的小直径深孔加工工艺试验,试验效果良好。一、振动钻削系统与内排屑深孔钻振动…     

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.     

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.