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由于铝合金壳体铸件的形状不规则,部分结构不易加工,加大了铸造难度,长期制约生产企业的发展。对铝合金壳体铸件结构以及铸造工艺进行了阐述,分析了铸造过程中的难点以及缺陷,重点探讨了铝合金壳体的铸造改进方案。期望对其他类似壳体的铸造提供参考。 相似文献
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针对Al-5Mg-3Zn-1Cu铝卡钳壳体的倾转铸造工艺,利用ProCAST软件对铸件充型和凝固过程进行模拟,分析缺陷形成原因。对卡钳壳体结构进行优化,扩大铝液流动和补缩通道,并进行数值模拟和试制验证。结果表明,优化后的铸件实现了顺序凝固,避免形成孤立液相区并消除了缩孔缺陷。采用倾转铸造工艺试制的Al-5Mg-3Zn-1Cu铝卡钳壳体铸件表面光洁,内部组织致密均匀,且无缩孔、缩松缺陷。 相似文献
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在分析用立式铸造工艺生产主汽阀壳体方案的基础上,提出了卧式工艺方案,减少了分型面,简化了造型过程,消除了错型、错芯缺陷,尤其是有利于补缩和用冷铁在热节部位形成人工冷端,实现顺序凝固。用卧式工艺方案生产47MW联合循环汽轮机主汽阀壳体一次浇注成功,铸件经检验符合技术要求,证明这是一种可行的铸造工艺方案 相似文献
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204Cu钢是一种含铜、低镍和以氮强化的奥氏体不锈钢,其冷加工性能优于200系不锈钢,与304不锈钢相近。为获得具有2B表面的含1%N i的204Cu钢冷轧卷材,冷轧后要进行退火、电解、冷酸洗。退火的目的是消除组织缺陷,细化晶粒,降低硬度,改善加工性能,其关键是退火温度的选择和控制。 相似文献
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加入WTO给当代大学生带来的若干思考 总被引:3,自引:0,他引:3
入世对大学人才培养目标、社会人才需求、大学生知识结构、学习理念、就业市场等提出了新的要求,当代大学生必须提高自身的综合素质,培养创新能力,开阔国际视野,重视非智力因素的培养等,以此来适应WTO对人才的需求。 相似文献
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4320H风电机齿轮需进行渗碳、淬火,达到表面硬度58~62HRC、心部硬度33~44HRC、有效硬化层(至515HV0.5)深度2.0~3.0mm,有非马氏体组织的深度≤0.05mm,马氏体1~4级,心部铁素体1~3级,但无连续网状碳化物。采用UBE密封箱式炉对4320H钢齿轮进行了渗碳、淬火。通过热处理工艺的调整,最终达到了上述质量要求。 相似文献
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Aude Simar Marie-Noëlle Avettand-Fènoël 《Science & Technology of Welding & Joining》2017,22(5):389-403
Friction stir welding is a rather recent welding process (patented in 1991 by Thomas et al., ‘Improvements to friction welding’ UK patent application no. 9125978.8, US Patent 5460317, 1995) that has shown great potential for welding dissimilar materials even of different metallic nature, e.g. Al to steel, Mg to steel, Al to Ti, Mg to Ti, Al to Cu, Al to Mg. This review presents the specific microstructural features and mechanical properties, in particular tensile strength, of such welds. A focus will be on the material flow and welding defects, on the intermetallic compounds, on constitutional liquation, on particularities related to dissimilar lap welding and finally on process modifications to improve dissimilar friction stir weldability. 相似文献
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In this paper, we propose a new information theoretic method called structural information control for flexible feature discovery. The new method has three distinctive characteristics, which traditional competitive learning fails to offer. First, the new method can directly control competitive unit activation patterns, whereas traditional competitive learning does not have any means to control them. Thus, with the new method, it is possible to extract salient features not discovered by traditional methods. Second, competitive units compete witheach other by maximizing their information content about input patterns. Consequently, this information maximization makes it possible to control flexibly competition processes. Third, in structural information control, it is possible to define many different kinds of information content, and we can choose a specific type of information according to a given objective. When applied to competitive learning, structural information can be used to control the number of dead or spare units, and to extract macro as well as micro features of input patterns in explicit ways. We first applied this method to simple pattern classification to demonstrate that information can be controlled and that different neuron firing patterns can be generated. Second, a dipole problem was used to show that structural information could provide representations similar to those by the conventional competitive learning methods. Finally, we applied the method to a language acquisition problem in which networks must flexibly discover some linguistic rules by changing structural information. Especially, we attempted to examine the effect of the information parameter to control the number of dead neurons, and thus to examine how macro and micro features in input patterns can explicitly be discovered by structural information. 相似文献
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模具浇口对注塑件熔接痕的影响及其危害显而易见.从塑件熔接痕形成机理出发,将模具浇口的数量、位置、形式、尺寸等对熔接痕的影响及其防止与选择进行了阐述,目的是从浇口源头防范对塑件熔接痕的影响,尽量控制熔接痕形成. 相似文献
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和谐文化建设是个大课题,特别要引起高等教育界、高等教育研究界认真的探索.高等教育要建设和谐文化,首先是要提高高等教育的文化自觉,要重视文化建设、加强文化建设;要处理好多种文化的关系,倡导一种尊重差异、包容多样的文化环境和氛围,不断增强高等教育发展的生机和活力;视和谐文化建设为己任,把和谐文化建设与高等教育自身改革发展密切结合起来.和谐文化建设含义丰富,高等教育应该为社会和谐建设、和谐文化建设贡献力量. 相似文献