强化研磨加工最佳工艺参数的实验研究

简要介绍了强化研磨加工的原理,并讨论了影响强化研磨加工效果的工艺参数,通过实验研究,分析了喷射压力、喷头移动速度、喷射距离这三个主要因素对加工后模具钢表面粗糙度和表面硬度的影响,根据试验数据,分析得出了强化研磨加工针对45#模具钢表面处理的最佳工艺参数为:喷射压力0.5MPa,喷头移动速度50mm/min,喷射距离45mm。     

强化研磨喷射角度对轴承套圈加工质量的影响

强化研磨是一种新型轴承强化加工方法,集合了强化塑性、研磨微切削以及摩擦化学加工技术。在额定转速时对喷射角度进行单一变量试验,检测轴承套圈内圈沟道表面粗糙度与硬度的变化,分析喷射角度对加工质量的影响及作用机制,并探讨粗糙度与硬度的分布均匀性,以提高加工质量。     

强化研磨加工中喷射角度对GCr15轴承钢板塑性变形的影响

利用ABAQUS有限元仿真软件研究不同喷射角度强化研磨加工GCr15轴承钢板过程的塑性变形,得到不同喷射角度与等效塑性应变沿真实路径距离的关系,并通过拉伸试验进行验证。喷射角度为90°的强化研磨加工伸长率为1.4%,相比未经过强化研磨加工的伸长率数值缩减了2.0%。断口收缩率由空白组的4.9%降低到喷射角为90°的2.2%。结合仿真和试验可知,强化研磨加工中喷射角度越大,塑性变形能力越低,材料加工越难。     

强化研磨对GCr15轴承钢耐蚀性的影响

通过改变强化研磨喷射角度对GCr15轴承钢进行加工，并开展盐雾腐蚀试验，结合腐蚀动力学曲线、傅里叶红外光谱图、腐蚀微观形貌图、三维形貌图进行腐蚀机理分析。结果表明：盐雾腐蚀试验后强化研磨试样得到的n=0.723 8,且腐蚀产物中γ-FeOOH的占比较低，表明强化研磨试样腐蚀产物层对基体材料的保护性能更好；随着强化研磨喷射角度的增加，试样耐蚀性能变好，试样表面逐渐由均匀腐蚀转化为边缘点蚀，试样的腐蚀速率逐渐降低；强化研磨喷射角度为90°时，GCr15轴承钢腐蚀速率为0.060 4 mm/a,耐蚀等级为5,腐蚀速率远低于未强化研磨试样，表明强化研磨加工可使工件具有较好的耐蚀性。     

强化研磨喷射压力对轴承表面残余应力的影响

为研究强化研磨加工与轴承工件强度之间的关系,首先从理论上分析表面残余压应力对轴承工件裂纹扩展速率的影响,并通过实验验证强化研磨对提高轴承表面残余应力具有显著效果。结果表明,在保证工件粗糙度的情况下,要提高轴承表面残余应力,在强化研磨加工中喷射压力最好控制在0.4-0.6MPa。     

强化研磨微纳加工残余应力的数值模拟分析

为了探究强化研磨微纳加工中磨粒喷射速度和喷射角度对残余应力场分布的影响,采用ABAQUS有限元分析软件进行数值模拟,建立了表面覆盖为100%的单颗粒磨粒撞击GCr15轴承钢靶材的模型。利用单一控制变量的方法对比了不同速度和不同角度下仿真模拟靶材表面残余应力的大小以及残余应力层深。研究结果表明,强化研磨微纳加工可以在靶材引入0.09~0.143 mm的残余应力层,最大残余压应力和表面残余压应力值具有一定的正相关性,在喷射角度为5π/12和喷射速度在60 m/s的组合工艺参数下,可以获得最大残余应力。     

强化研磨喷射时间对内圈沟道尺寸和残余应力的影响

以SKF61910深沟球轴承内圈加工为例,基于Abaqus/Explicit建立强化研磨三维随机碰撞模型,分析强化研磨喷射时间对轴承内圈沟道尺寸和残余应力的影响,结果表明:随喷射时间增加,在2 min前内圈沟道尺寸增大,2～ 12 min时内圈沟道尺寸减小,12 min后不再显著变化;随喷射时间增加,轴承内圈沟道表面残...     

强化研磨加工中喷射时间对钢球磨损的影响

通过理论与试验结合研究强化研磨加工过程,喷射时间对强化研磨料中的钢球磨损的影响。通过钢球表面SEM放大图观察其表面形貌,通过分析钢球表面粗糙度的变化间接分析钢球表面的磨损程度。试验研究表明:在设定的试验条件下,强化研磨加工22 min后则需更换强化研磨料中的钢球,否则会造成已磨损的钢球对工件表面刮伤,产生不利的影响。     

更正

正《轴承》2013年11期目次页"试验与分析"栏目"强化研磨加工中喷射压力对工件表面粗糙度的影响"一文,第2作者"包右文"应为"包佑文"。     

强化研磨喷射角度对GCr15轴承钢加工的影响

利用ABAQUS有限元仿真软件进行强化研磨加工模拟,并采用用户子程序UMAT定义材料的本构关系。在保持喷射平均速度和喷射压力不变时,通过改变喷射角度得到Mises应力和碰撞能量在55°时最佳。对比应力—应变曲线图与强度与塑性的配合曲线图可知,GCr15轴承钢是中等强度、中等塑性和高韧性的材料。试验表明,在55°～60°时强化厚度最优,具备良好的油囊结构;在45°～55°时硬度表现最佳。结合仿真和试验强化研磨喷射角度可知,在55°左右可获得良好的机械性能。     

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.     

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.