表面微织构刀具切削加工技术

刀面微织构改变了刀具与切屑之间的摩擦状态,表面微织构刀具在切削中能够降低刀具磨损、提高刀具寿命和切削性能,研究表面微织构刀具的切削加工技术具有重要意义。通过对表面微织构刀具切削加工技术进行综述,介绍了表面微织构刀具制备方法以及表面微织构刀具在切削加工过程中的切削力、切削温度、刀具磨损、工件加工表面粗糙度的影响规律,梳理了表面微织构在不同刀具上的应用,对表面微织构刀具切削加工技术的未来发展趋势进行了展望。     

氧化锆陶瓷车削中刀具表面微织构参数对切削性能的影响

利用飞秒激光加工技术在硬质合金车刀后刀面加工出不同宽度和间距的沟槽型表面织构。通过氧化锆陶瓷材料干切削试验,研究织构化刀具磨损机理,分析织构参数对切削力和刀具磨损量的影响规律。实验结果表明：具有合理参数的后刀面织构化刀具能够明显降低切削力,减少刀具磨损。沟槽型织构通过储存切屑、稳定黏结物和对已加工表面上硬质点的二次切削作用,降低刀具后刀面的黏着磨损和磨粒磨损。织构的二次切削作用会导致切削力增大,与织构的减摩作用共同影响切削力。     

微织构自润滑刀具干切削0Cr18Ni9奥氏体不锈钢的切削性能

采用激光加工方法在硬质合金刀具的前刀面加工出微织构,并在微织构中填充固体润滑剂制成微织构自润滑刀具;使用微织构自润滑刀具、微织构刀具以及传统硬质合金刀具分别对0Cr18Ni9奥氏体不锈钢进行干切削试验,并对比了它们的切削性能。结果表明:与传统刀具相比,微织构自润滑刀具能有效提高切削性能(主切削力减小了8%~16%,切削温度降低了15%~24%),增加切屑的曲卷,改善刀具的粘着磨损现象。     

不同润湿性微/纳织构化刀具切削性能研究

针对15-5PH固溶处理不锈钢等难加工材料切削过程中刀具磨损快速的问题,采用激光加工及表面处理技术制备得到不同润湿性的硬质合金微/纳织构化刀具。通过对15-5PH固溶处理不锈钢的切削试验,研究了不同润湿性微/纳织构化刀具的切削性能及减摩机理。试验结果表明:在微量润滑条件下,刀具表面低润湿性微/纳织构的存在可有效降低切削力、前刀面平均摩擦系数及切削温度,同时还能进一步改善刀—屑界面的润滑状况,减缓刀具磨损。     

微织构刀具织构参数优化仿真研究

高温镍基合金在切削加工过程中,较大的切削力会产生较高的切削温度,造成刀具磨损严重、加工表面质量差等加工难题。在刀具前刀面加工区域,设计微观织构(微织构)可以改善切削加工中刀-屑接触面的摩擦润滑状态,从而改善刀具的切削性能。采用有限元仿真软件对正弦型微织构刀具进行切削镍基合金的仿真实验,通过正交实验研究正弦型微织构刀具的织构刃边距、织构宽度、织构间距、正弦曲线幅值和周期长度5个织构参数对刀具切削性能的影响,并优化了正弦型微织构刀具的织构参数。结果表明:正弦型微织构刀具的主切削力降低程度与织构参数密切相关,且织构参数对主切削力大小的影响程度依次为:织构刃边距织构间距织构宽度正弦曲线幅值周期长度。优化后得到的刀具切削力、切削温度和断屑能力优于优化前无微织构刀具。     

微织构刀具超声振动辅助加工切削性能仿真研究

对微织构刀具在超声振动辅助加工时的切削性能进行仿真研究。在研究中,在CAXA软件中建立刀具参数相同的二维刀具和微织构刀具,导入AdvantEdge软件,分别进行二维普通刀具切削、二维微织构刀具切削、二维普通刀具超声振动切削、二维微织构刀具超声振动切削,对比分析四种切削的仿真结果。通过仿真研究发现,微织构结构可以有效降低刀具温度,高温区域明显减小,同时可以减小刀具应力,减小高应力区域,对切削力的影响则不大。超声振动辅助加工可以有效减小切削力,降小刀具应力,对刀具温度的影响则不大。微织构结构和超声振动辅助加工同时作用,刀具温度最低,切削力和应力最小,并且可以延长刀具寿命。     

表面织构陶瓷刀具切削性能研究

采用激光在Al2O3/TiC陶瓷刀具前刀面加工出不同的表面织构,制备出纳米织构陶瓷刀具及微纳米复合织构自润滑陶瓷刀具,并与传统陶瓷刀具进行干切削45淬火钢试验比较.结果表明:纳米织构陶瓷刀具不能够有效降低切削力、改善刀具黏结现象,但是可以减小刀具前刀面磨损凹坑,减少磨粒磨损;微纳米复合织构自润滑陶瓷刀具能够有效降低切削力,减小刀具磨损,改善刀具的切削性能.     

一种刀具表面阶梯型微织构的作用机理分析

为了探究阶梯状微织构在刀具表面存在的作用及其相关机理,并获取最优的织构参数,利用激光加工设备在硬质合金刀具表面加工出不同参数的凹坑织构,利用摩擦磨损试验机进行销盘式摩擦磨损实验,并通过车床进行了切削铝合金的实验.结果 表明,当刀具表面凹坑织构的直径为65μm、凹坑深度为15μm时,与无织构表面相比,具有凹坑织构表面的摩擦系数降低了43.5％,与硬质合金相对磨的铝合金销的磨损量减小了40.2％,在切削加工中具有织构纹理的刀具的主切削力降低了10.4％.从上述结果来看,刀具表面的阶梯状微织构能够有效起到减摩降磨的作用,同时改变切屑类型,大幅提升刀具的使用寿命.     

织构化AlCrN涂层刀具车削加工奥氏体沉淀硬化不锈钢的切削性能研究

在基体为WC基硬质合金的Al Cr N涂层刀具前刀面应用激光技术加工出平行于切削刃的微织构,制备Al Cr N涂层织构化刀具;在液体润滑条件下对奥氏体沉淀硬化不锈钢(0Cr15Ni25Ti2Mo Al VB)进行切削试验,研究其切削性能,并与传统Al Cr N涂层刀具进行比较。分析了切削速度对切削力及切削温度的影响,并采用扫描电子显微镜(SEM)与X射线能谱仪(EDS)观察刀具的磨损形貌。研究结果表明:与传统Al Cr N涂层刀具相比,Al Cr N涂层织构化刀具能够有效降低切削温度、切削力和刀—屑接触面摩擦因数;由于微织构的存在,液体润滑时,润滑剂能够渗入到Al Cr N涂层织构化刀具的刀—屑接触面,因而具有良好的抗粘着性及耐磨性。     

微孔织构车刀设计与高速微车削试验

针对微型刀具高速微切削过程中磨损严重的问题,基于表面非光滑技术,在刀具表面进行微孔织构设计,并采用Deform 3D进行金属切削动态模拟分析。分析表明,前刀面带有微孔织构的微型车刀主切削力、刀尖最高温度、刀具磨损量,与无织构车刀相比都明显降低。利用微细电火花加工技术在微型车刀表面加工微孔织构,使用自行研制的高速微车削实验装置进行6061铝合金的微加工实验,并从刀具表面磨损状况、切屑形态、已加工表面粗糙度3个方面进行评价。实验结果表明,微孔织构在提高刀具减磨性能和已加工表面质量方面效果良好,微织构改善了切屑形态,增强了刀具排热、抗黏结性能。     

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.