热处理篇

正本期热处理篇安排了曲轴热处理、淬火工装及感应热处理方案。曲轴热处理主要以汽车发动机曲轴断裂失效分析为主,并分享了曲轴气体软氮化技术;淬火工装栏目主要以突出工装在淬火工艺中的作用;感应热处理栏目以推广感应热处理技术,并以解决实际问题来反应当前应用企业的工艺现状等。     

42CrMoA钢大功率柴油机曲轴热处理工艺开发

对42CrMoA钢大功率柴油机曲轴的技术参数和热处理工艺难点进行了分析,在工艺试验的基础上,最终确立了该大功率柴油机曲轴的热处理工艺方案和工艺参数,实现了大型中碳低合金钢曲轴水淬的工艺突破,保证了曲轴的力学性能达到技术要求,并成功将该工艺应用于批量生产。     

面向21世纪的曲轴新材料

对发动机曲轴材料作了综合介绍。根据它的发展历史以及对各种种材料的化学成分、组织、性能、加工工艺、成本价格的比较分析,说明其发展趋势是以球铁曲轴替代锻钢曲轴,以铸态珠光体球铁曲轴替代热处理曲轴。球铁代钢的关键是提高韧性,自行研制的ＱＴ７４０－３铸态珠光体球铁曲轴表明,铸态球铁性能达到了一个新高新。另外对几种曲轴新材料进行了分析。     

PC微机在曲轴热处理自动控制中的应用

一、工艺流程及PC控制原理曲轴是柴油机的一个重要零件。我厂的曲轴热处理工艺过程是通过中频感应器,通以8000Hz、600V电压、120A中频电流,使曲轴感应加热,然后喷水冷却。工艺员必须制订出最佳工艺参数,如加热功率、淬火液喷流量等参数。该曲轴热处理有三档加热、三档冷却     

柴油机球铁曲轴热处理工艺的改进

我厂110、120系列柴油机球墨铸铁曲轴,自正式投产以来,二十余年热处理工艺一直采用正火——回火工艺。这一工艺也为国内生产类似曲轴的工厂所采用。有人认为,球铁曲轴的回火工艺是可以取消的。     

曲轴变形的分析与控制

在高温下长时间保温去除应力后的锻件曲轴,在粗加工时发现,曲轴主轴径的跳动超差,无法满足加工要求。经分析得出:曲轴在长期放置中,工件内部残余应力重新分布,并通过工件形变得以释放。通过调整热处理工艺以及校直方法,从而有效去除应力,实现了对大中小型曲轴热处理变形的控制。     

并线生产曲轴柔性热处理装置的设计研究

曲轴热处理变形的主要影响因素是自重和热传递。文中以有限元法为基础,分析曲轴不同放置方式时的热处理变形,通过研究可知：曲轴热处理时,与水平放置相比,竖直放置时因自重而产生的变形大大减小,变形量降低了78.2%。依据以上研究结果,基于仿形机构原理,设计了一种并线生产柔性曲轴热处理装置,该装置主要包括定位机构、自动上下料机构、同步运动机构、热处理机构等,热处理时曲轴竖直放置,可以同时对多个轴颈并行热处理;同时,针对自动上下料机构,设计了专门的采用PLC控制的液压与气动系统。该装置曲轴热处理节拍快、轴颈加热均匀、变形量小、热处理柔性好,能适应四缸、六缸等多种曲轴的在线生产热处理。     

中国南车大中型船机曲轴工艺再上新台阶

不久前,南车资阳机车有限公司的“大中型船用柴油机曲轴制造工艺开发”、“RR曲轴镦锻装置精化曲轴锻件工艺研究”、“曲轴热处理控时淬火技术应用研究”等三项工艺开发成果通过了四川省科技厅的科技成果鉴定。这三项工艺成果的总体技术均达到国际或国内领先水平,有力地改变了我国大中型船机曲轴长期依赖进口的状况。     

摩托车曲轴模具的制造工艺

本文介绍了摩托车曲轴模具结构特点,分析了它的工作环境,对模材性能提出要求,介绍了曲轴模具新的制造工艺,在取材、热处理、表面处理等方面与传统工艺相比较其的优势。     

一种曲轴竖置热处理装置设计

热处理是曲轴加工中至关重要的工序,曲轴平置热处理,变形量大且需要增加回火热校直工艺。用竖置热处理代替平置热处理,因曲轴自重产生的变形量减小了78. 2%。基于同步传动仿形机构原理,设计了曲轴竖置热处理装置,包括定位夹紧机构、传动机构以及加热机构等,定位夹紧机构采用顶尖和卡盘定位夹紧;传动机构利用锥齿轮副和同步带同步传动保证加热机构和曲轴一起随动,避免划伤轴颈表面;加热机构采用隔热水套隔热保温。     

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.     

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....     

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.     

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.