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罗守靖 《机械工人(热加工)》2004,(4)
二、半固态金属的二次加热(局部加热) 在半固态棒坯触变成形之前,先要根据零件重量,精确分割经流变铸造获得的半固态棒坯,即所谓下料。然后在感应炉中加热至半固态以供后续成形,这便是二次加热。经二次加热,可获得不同体积分数的半固态浆料,同时也可使在制坯工序所获得破碎枝晶组织球化、均匀化,有利于触变成形。 相似文献
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半固态等温热处理对K4169合金组织和性能的影响 总被引:1,自引:0,他引:1
研究了等温热处理温度和保温时间等工艺参数对K4169高温合金半固态组织演变和力学性能的影响.结果表明,半固态等温热处理可以将K4169高温合金铸态组织中的枝晶转变为球形晶粒组织,在升温过程中晶界处部分7相发生溶解,随着温度的升高,γ+γ共晶相开始熔化,初生γ相在等温处理中逐渐演变为球状;等温温度越高,半固态重熔和初生γ相的演变过程越快,等温温度过高或保温时间过长,试样易发生变形且球形晶粒趋于长大;K4169高温合金半固态等温热处理时的最佳热处理工艺为加热温度1 310℃左右,保温时间为90~120 min,或加热温度1 320℃左右,保温时间为45~60 min;半固态等温热处理对合金压缩强度的影响与合金的组织形态有关,半固态K4169高温合金的硬度与铸态相比有所降低. 相似文献
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罗守靖 《机械工人(热加工)》2004,(4):87-89
在半固态棒坯触变成形之前,先要根据零件重量,精确分割经流变铸造获得的半固态棒坯,即所谓下料。然后在感应炉中加热至半固态以供后续成形,这便是二次加热。经二次加热,可获得不同体积分数的半固态浆料,同时也可使在制坯工序所获得破碎枝晶组织球化、均匀化,有利于触变成形。 相似文献
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基于半固态金属加工原理,采用合金热力学计算方法,对Al-Si-Mg系适合半固态加工的合金成分进行了优化设计,并在此基础上开展了试验研究。结果显示:1)采用国际通用的ThermoCalc软件能够成功地对Al-Si-Mg系合金成分进行优化设计,并且计算结果与试验结果具有较好的一致性;2)优化后的Al-6Si-2Mg合金在各工序中都表现出良好的半固态加工性能,连铸和二次加工过程的稳定性和可控性大大提高,坯料的凝固组织更加细化、球化和均质化;3)通过优化工艺,最终获得了Al-6Si-2Mg合金半固态触变成形的工艺参数和外观完整、性能优良的半固态压铸件,为半固态触变成形的工业应用打好了基础。 相似文献
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研究低温浇注工艺对ZL104铝合金半固态重熔加热过程中组织变化的影响。实验结果表明,降低浇注温度可细化合金的铸态组织,进一步细化半固态重熔过程中球形初生-αAl晶粒,当浇注温度为605℃,在580℃下半固态保温20~30min时,初生-αAl呈细小、均匀、球形的晶粒,满足ZL104铝合金触变成形组织的要求。 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
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. 相似文献
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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. 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
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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.... 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
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. 相似文献