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991.
992.
薄板激光拼焊工艺研究 总被引:1,自引:0,他引:1
汽车薄板的激光拼焊可以减轻整车质量和制造成本,对提高汽车设计的灵活性具有重要意义.通过对汽车用冷扎薄钢板和镀锌板的激光拼焊的实验研究,表明虽然激光焊接接头的塑性有所下降,但其焊接强度与母材差不多,且焊接影响区小,对汽车覆盖件和地板等零件的焊接获得很好的效果. 相似文献
993.
2005年上半年,我国共生产海绵钛3801.6t,同比增长68%;生产钛粉342.5t,同比减少了76.5t;生产钛加工材5033.9t,同比增加了17%。2005年上半年,我国海绵钛进口量大幅减少,仅642t,钛加工材却大幅增加,达3024t。尽管从2004年开始,海绵钛及钛加工材价格大幅t涨,但我国对海绵钛和加工材的需求乃明显上升,预计2005年我国海绵钛的需求在万吨左右,而实际产量估计达到9000t左右,与实际需求稍有差距。世界海绵钛的生产能力不断扩大,预计2005年全球海绵钛的供应能力将增加23%,下半年海绵钛价格将趋于平稳。 相似文献
994.
995.
M. A. Hassan N. Takakura K. Yamaguchi 《International Journal of Machine Tools and Manufacture》2003,43(6):637-646
A new process on friction aided deep drawing has been developed in which a metal blank-holder divided into eight fan-shaped segments is used instead of an elastomer ring used in the Maslennikov process. This blank holding device consists of four drawing segments and four small wedges, which can move radially in- and out-wards under a certain blank-holding pressure. The drawing process can be efficiently performed using an assistant punch, which partially supports the deformation of the blank as well as improving the shape and dimensional accuracy of the drawn cup. Deep drawing experiments have been done using soft aluminum sheets of 0.5 and 1.0 mm in thickness to understand the main features of the proposed drawing process. Theoretical analyses based on the energy and slab methods have also been conducted to study the effect of main process parameters on the minimum blank holding pressure required for the onset of deformation, and to obtain the other optimum working conditions. The possibility of the new process has been confirmed by producing deep and successful cups with a drawing ratio of 4.0, although the number of drawing operations is still high. 相似文献
996.
997.
Vipul Ranatunga Jay S. Gunasekera 《Journal of Materials Engineering and Performance》2006,15(1):47-52
The paper summarizes the development of numerical procedures for modeling bulk deformation process and preform designing techniques
based on the upper bound elemental technique (UBET). UBET has a unique place where an approximate, but faster solution is
needed for decision making. In designing and optimizing multistage forging and profile ring-rolling processes, an approximate
solution can be used to identify the most influential process parameters. Once an optimum combination of process conditions
are determined, computationally intensive, but more accurate finite element analysis can be used to verify and refine results.
In this paper, UBET procedures for closed-die forging and profile ring rolling are high-lighted. Experimental investigations
are used to validate the model predictions. Also, the UBET-based preform design tool is presented as a process and die design
tool for multistage forging processes. Application of these techniques is presented with evidence of effective material usage
and extended overall die-life. 相似文献
998.
F.X. Wang X.P. Gao Z.W. Lu S.H. Ye J.Q. Qu F. Wu H.T. Yuan D.Y. Song 《Journal of Alloys and Compounds》2004,370(1-2):326-330
In this work, effects of partial substitution of Mg, Ni with AB2 in Mg-based alloy and subsequent surface modification by further ball-milling with carbon nanotubes (CNTs) on electrochemical properties were investigated. Mg1.9(AB2)0.1Ni0.8 (AB2=LaNi2, LaNiCo and LaNiMn) alloys were prepared by solid-state diffusion method, the nanocrystalline Mg-based alloys were prepared by ball-milling the mixture of obtained Mg1.9(AB2)0.1Ni0.8 alloys and nickel powder. It was found that the electrochemical capacities of nanocrystalline Mg1.9(AB2)0.1Ni1.8 alloys were measured to be 460–490 mAh/g. The nanocrystalline Mg-based alloys containing carbon nanotubes (10 wt.%) obtained by ball-milling after 60 min were demonstrated to show improved electrochemical properties with respect to the original nanocrystalline Mg-based alloys. The electrochemical reaction activity was detected by electrochemical impedance spectra (EIS). Raman and X-ray photoelectron spectroscopy (XPS) proved the interaction between Mg1.9(AB2)0.1Ni1.8 alloys and carbon nanotubes after ball-milling, which resulted in an increase in the surface Ni/Mg ratio. 相似文献
999.
1000.