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321不锈钢V形件充液成形失稳控制研究 总被引:2,自引:0,他引:2
充液成形技术是一种有效解决复杂薄壁零件成形问题的方法.针对321不锈钢V形件常规拉深成形需要多道次成形、工艺冗余的问题,通过分析V形件充液成形过程中易出现失稳现象,设计了带初始反胀的充液成形的技术方案.结合数值模拟,对薄壁V形件充液成形过程中出现的凸模侧壁破裂、法兰区起皱等失稳形式进行了研究,优化了液室压力加载曲线、压边间隙、初始反胀压力及初始反胀高度.结果表明,V形件在优化的工艺参数条件下成形既可产生“摩擦保持”的效果,改善了应力状态,又可避免凸模侧壁破裂和法兰区起皱,提高了零件成形极限和壁厚分布的均匀性. 相似文献
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深腔类盒形件充液成形技术研究 总被引:1,自引:0,他引:1
充液成形技术是一种有效提高材料成形极限的方法。针对深腔类盒形件相对拉深高度大、常规拉深成形多道次、成形质量差的问题,通过分析盒形件充液成形过程中易出现失稳的原因,设计了带预胀充液成形的技术方案。针对高盒形件充液成形过程中出现的凹模圆角侧壁破裂、法兰区起皱等失稳形式进行数值模拟分析,得到了较为合理的工艺参数。并通过工艺试验分析了成形过程中压边间隙、液室压力、初始反胀等因素对零件成形性能的影响,最终得到了高质量的成形零件。 相似文献
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运用板料成形有限元软件,对磁力泵隔离套零件的充液拉深成形过程进行模拟,获得成形后的零件成形极限图(FLD)和侧壁厚度分布图,研究了在确定的压边力、凹凸模圆角半径和摩擦系数下,液室压力、压边间隙对零件成形质量的影响规律。研究表明,当液室压力为40 MPa时,侧壁厚度分布范围在0.932~1.027 mm之间;压边间隙为1.08 mm时,零件的侧壁厚度最大减薄率为8.8%;通过控制液室压力为40 MPa、压边间隙为1.08 mm时,试验件壁厚均匀、减薄率低,获得较佳的成形效果,试验结果也进一步验证了结论的有效性。 相似文献
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铝合金覆盖件的应用是汽车轻量化的关键,但其制造难度较大。通过研究铝合金发动机罩外板的充液成形工艺过程,了解先进柔性技术在汽车领域应用的可行性。分析了工艺参数中液室压力与凸模行程匹配及压边力对板料减薄率的影响,从成形极限上判断零件无起皱、破裂现象的范围。获得最优的整形液室压力为12~20 MPa,压边力过小,板料不能充分塑性变形,压边力过大,板料易失稳破裂,最优的恒定压边力范围为1600~2000 k N。研究表明,采用板材充液成形柔性制造工艺,可降低噪音,无冲击线,且由于液室压力的作用,滑移线减小,可提高大型铝合金弱刚度板材的质量。 相似文献
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封条式铝合金热交换器用途广泛、可靠性高,采用氮气保护钎焊具有生产效率高、温度均匀性好、成本低等特点。本研究介绍了封条式铝合金热交换器的结构特点、材料和用途,并介绍了适用于氮气保护钎焊批量生产的钎焊设备、流程、方法和参数。钎焊是产品生产的关键工序,钎焊失效往往导致产品报废,合格率的下降,进而导致成本的上升。本研究把在生产实践中遇到的主要失效模式根据失效件的特点分为顶板变形、零件移位或变形、温度超高或过低、钎缝泄漏等4大类,分别对这各类失效模式产生原因进行了分析,并针对失效模式的根本原因,从钎焊夹具设计、过程管理、钎焊工艺、零件清洁等方面提出了预防与改进措施,在生产实践中取得了良好效果。 相似文献
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L. L. Shreir 《工业材料与腐蚀》1970,21(8):613-629
Review of electrochemical methods of studying hydrogen embrittlement and stress corrosion cracking In this review the authors presents the features common to both types of failure and the features by which the two types of failure are different from each other. In this context it is emphasized, that the hydrogen absorption - essential for embrittlement - can be regarded as a side reaction accompanying the particular overall reaction, and that the particular reaction conditioned and the structure of the metal play an important part. Different methods for investigating the hydrogen context and the state of the hydrogen (atomic, ionic, molecular) in the metal are described, and soo are methods for studying internal stresses due to hydrogen absorption. As to stress corrosion cracking it is shown that the processes involved are not a separate mechanical and a separate chemical one, but that the joint action of both is important. In this context it is shown, however, that this view can be considered to be established in th e case of austenitic steels only. 相似文献
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Friction stir welding of AZ31 magnesium alloy rolled sheets: Influence of processing parameters 总被引:1,自引:0,他引:1
The temperature evolution during friction stir welding (FSW) and the resulting residual stresses of AZ31 Mg alloy were studied to get a better understanding of the mechanisms involved in this process. The relationship between the processing parameters, the heat and plastic deformation produced and the resulting microstructure and mechanical properties was investigated. Increasing the shoulder diameter or the tool rotation speed or decreasing the welding speed produced an increase in the heat generated during the process and then promoted grain growth. The temperature distribution on the advancing side and on the retreating side differed, and stress levels were higher on the retreating side. The grain size heterogeneity produced by FSW was not the prevailing cause of failure. 相似文献
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精密硬态切削过程金属软化效应与表面塑性侧流的研究 总被引:3,自引:0,他引:3
由于普通CNC车床上实施精密硬态车削仍存在被加工表面机械性能不稳定的因素,从而导致该工艺的实施仍面临挑战且不易实现良好的加工表面质量。本文通过实验研究了精密硬态车削淬硬GCr15轴承钢,讨论了PCBN刀具后刀面磨损对已加工表面材料塑性侧流的作用。实验结果表明,由于刀具后刀面磨损量增大导致高的切削温度从而使金属软化是决定材料塑性侧流形式的决定性因素,当后刀面磨损量超过0.2mm时,发生严重塑性流动,已加工表面与原始表面微观组织无明显变化,而显微硬度有所提高。 相似文献
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分析了烘干机热风罩零件的冲压工艺及其结构特点,叙述了热风罩侧成形冲孔模的结构特点及模具工作过程,介绍了模具主要零件的设计及其加工工艺。该模具将侧滑块结构进行了延伸,采用双滑块同向移动结构,实现了零件侧凸台与圆孔的形成,同时保证了方便地送料、取料,生产效率高,零件质量稳定。 相似文献
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介绍车型侧面碰撞试验,并对试验过程中防撞杆开裂的问题开展系列检测与分析,如外观观察、金相组织分析、断口分析以及三点弯曲试验等,最终查明零件失效的根本原因并提出整改方案。结果表明:防撞杆材料为高强度焊管,经过淬火+低温回火后材料组织敏感性较高;防撞杆在与支架进行二氧化碳保护焊接过程中受到焊接热的影响,进而导致焊管局部材料组织发生转变、力学性能遭到弱化,侧面碰撞时从薄弱区发生开裂。通过改变防撞杆与支架的焊缝布置方式,由周向焊接更改为纵向焊接,来减轻焊接热的影响,后续零件已经顺利通过碰撞试验。 相似文献
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Hong Yao Brad L. Kinsey Jian Cao 《International Journal of Machine Tools and Manufacture》2000,40(1):113
With the development of finite element method and computer technology, the complete modeling of the forming of a 3D sheet metal part is becoming realistic. However, an accurate 3D simulation is usually too time-consuming to be used in the early stage of design. One solution is to model the straight side of a 3D part as a plane strain problem and the corner section as an axisymmetric problem. Unfortunately, the axisymmetric solution often over-predicts the severity of the deformation at the corner and leads to a very conservative design. In this study, a modified axisymmetric model with a center offset is proposed to predict tearing failure in the corner sections of 3D parts. The proposed offset is found to be a function of the center strains, failure height, and tooling/process parameters, including tooling geometry, material properties, friction coefficient, and restraining force provided by the binder. Finite element analyses of both 3D and 2D axisymmetric models for square and rectangular cup forming are utilized to verify the proposed concept and to define the function. Excellent predictions of the failure heights are obtained. The proposed model enables engineers to rapidly specify the right amount of the restraining force in the corner section based on the desired center strains and forming depth. A detailed design algorithm is provided. 相似文献
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针对高强钢纵弧棱U型梁类件的冲压成形问题,分析了纵弧棱U型梁成形件各个区域的冲压变形特点,再通过有限元分析总结了其成形过程的应力、应变分布情况和厚度变化规律,并结合模拟结果与物理试验探讨了该类零件在成形过程的减薄和增厚行为.验证结果表明:该梁类件的主要变形区为翼板区,且厚度从端部至中部逐渐减小;主要危险部位处于中部侧壁... 相似文献