尼龙锁紧螺母冷镦工艺的仿真与优化

本文将尼龙锁紧螺母在冷镦过程中的六角形坯料简化为轴对称模型。利用有限元计算机辅助模拟分析软件,对在冷镦过程中存在问题进行了模拟分析。依据分析结果,结合实际工作经验．对模具结构及冷镦工艺参数进行了改进和优化。解决了模具寿命低的问题,实现了产品的批量稳定生产。     

锥形螺母冷镦挤数值模拟及模具设计

提出了锥形螺母一次冷镦挤复合成形新工艺,设计了采用管坯冷镦挤成形锥形螺母的模具结构,运用Deform-3D有限元软件,模拟分析了锥形螺母冷镦挤成形过程中坯料填充凹模型腔的流动速度场和等效应力场。结果表明:管坯各处的流动应力值均不超过其材料的流动应力极限,金属坯料可以流动到型腔的各个部位,此工艺能够获得形状完整的锥形螺母。     

硬质合金模具的再利用

硬质合金广泛应用于模具上,标准紧固件螺栓冷镦生产中大量使用缩径模,材质YG20C,如图1。目前,大多数标准件生产厂家都有相当数量的废旧缩径模等待回收。我们利用它改做其他模具的模芯,取得较好效果。 图2、图3分别为螺母多工位冷镦机和螺栓双击冷镦机上使用的割模,是用废缩径模改制成的,     

谈谈薄型六角螺母的冷镦工艺

本文根据生产实践，就用多工位冷镦设备生产薄型六角螺母的一些工艺问题谈些体会，供同仁参考。     

六角螺母冷镦成形工艺参数的确定及应用

在四工位螺母冷镦机上镦制六角螺母，其生产效率高、表面质量好，是生产螺母的一种很好的生产方式。但与五工位螺母冷镦机相比，由于少了一个工位（即镦混六方工步），镦球后只能直接镦六角成形，且在第三工位、第四工位之间无夹钳翻转装置，不利于外六方及内外倒角的成形，因此在坯料的用料直径选择以及变形工艺参数计算等方面均需要进行适当调整才能满足零件变形要求。     

钻头冷镦参数建模及成形工艺优化

针对40Cr钻头冷镦时废品率高且需预先进行热处理的问题,提出一种优化的冷镦成形工艺方法,即通过优化冷镦参数来减少热处理工序。通过分析冷镦过程的影响参数,建立了冷镦工艺参数的数学模型并进行了数值分析,得到了最优的冷镦参数。分别运用有限元模拟和试验的方法,对所得冷镦参数进行了验证。研究结果表明：运用该方法优化冷镦参数指导冷镦加工,材料无需进行热处理即可加工出符合要求的冷镦钻头。     

薄壁六角螺母冷镦过程中模具磨损模拟分析及参数优化

以薄壁六角螺母工位四冷镦下冲头模具为例,基于Archard磨损模型采用DEFORM-3D软件对下冲头磨损进行分析。选取冲压速度、摩擦因子、模芯圆角、初始模具硬度4个主要影响因素,以降低模具磨损量为目标设计4因素5水平的正交试验。结果表明,冲压速度对该下冲头磨损影响最为显著,然后依次为摩擦因子、模具硬度、模芯圆角。通过极差和方差分析法,对4个因素进行优化,得出最优组合工艺参数,并验证了采用优化参数可大幅降低模具的磨损量,延长下冲头使用寿命。     

冷镦内六角圆柱头螺栓成形工位凸模的改进

冷镦生产内六角圆柱头螺栓,其工位布置如图1所示。在生产中按图1的形式镦制,产品质量稳定可靠,满足了工艺要求。但成形工位凸模的寿命与加工却成了生产中的难题。于是我们对成形凸模的结构进行了改进,并取得了满意的效果,本文就此作以介绍。     

带法兰阶梯轴冷镦挤复合成形工艺研究

针对带法兰盘阶梯轴的结构特点,提出了镦挤复合成形工艺方案,并分别研究了在冷镦挤条件下,不同直径坯料对成形过程的影响.采用有限元模拟软件对带法兰盘阶梯轴的成形过程进行了数值模拟,比较分析了不同坯料尺寸对变形过程中金属流动、应变以及载荷曲线等的影响.试验结果表明,采用冷镦挤复合成形工艺成形带法兰盘阶梯轴,可以获得高质量和高精度的锻件,实现近净成形.     

半圆头车轮螺栓成形工艺研究

在金属材料挤压变形抗力较大的情况下,为了高效生产尺寸精度较高、产量较大、机械性能和外观质量较好的半圆头车轮螺栓,通过工艺试验,对半圆头车轮螺栓的生产成形工艺方案进行了分析比较,制定了在高效、多工位自动冷镦机上一次成形半圆头车轮螺栓的工艺方法。针对工艺难点,提出了解决措施,用简单的冷镦模具,生产出了合格的零件。     

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...     

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。     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.