共查询到19条相似文献,搜索用时 125 毫秒
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在液压直拉机上采用游动芯头拉拔成形智能手机用超薄超细无氧铜热管,研究了拉拔工艺对拉拔过程断管的影响,观察各道次铜管晶粒组织演变和拉拔过程中的力学性能和导电性能变化。结果表明:无氧铜管经游动芯头多道次拉拔,晶粒不断趋于沿拉拔方向的纤维状,同时抗拉强度和维氏硬度不断提升,而拉拔变形对导电率的影响比较小。当无氧铜管累计变形量达75.8%时,铜材的抗拉强度为416.5 MPa,继续拉拔容易发生断管问题,需进行中间退火。经过8道次拉拔变形,1次中间退火处理后,得到抗拉强度为403.8 MPa、伸长率为1.78%、导电率为98.85%IACS、外径公差为±0.02 mm、壁厚公差为±0.01 mm的Ф2 mm×0.08 mm规格的超薄超细智能手机热管。 相似文献
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为准确描述薄壁铜管游动芯头低频振动过程中拉拔力影响因素的变化,借助有限元分析软件MSC.Marc,建立铜管低频振动拉拔模型,分析拉拔速度、激振振幅、激振频率、模具锥角(外模半锥角、芯头半锥角)对拉拔力的影响。结果表明,拉拔速度的增加将引起拉拔力的小幅度增加,在激振频率为80~170Hz范围内拉拔力先减小后增大,激振振幅的增加将引起拉拔力的显著降低,外模半锥角与芯头半锥角存在最佳的模具锥角组合。 相似文献
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在拉拔过程中引入振动时,由于塑性成形中的"表面效应",可以减小拉拔成形过程中的摩擦力。基于有限元软件Marc,采用修正的滑动库仑摩擦模型,建立了薄壁铜管固定芯头振动拉拔模型,并对振动拉拔过程的摩擦与拉拔速度对摩擦的影响进行了数值模拟。结果表明:在薄壁铜管固定芯头拉拔过程中添加纵向振动可以减少铜管内外表面平均摩擦力,且幅值越大,频率越高,铜管内外表面平均摩擦力越小;拉拔速度为0~20 mm·s~(-1)时,随着拉拔速度增大,铜管内外表面平均摩擦力递增且上升趋势明显,拉拔速度大于20 mm·s~(-1)时,拉拔速度增大,铜管内外表面平均摩擦力增大,但增大的幅度小。 相似文献
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用长芯棒拉拔薄壁软铝管的试验研究 总被引:3,自引:0,他引:3
叙述了用长芯棒拉拔薄壁软铝管的实验设备、材料及工艺,研究指出,用长芯棒拉拔LF21铝合金管壁厚可薄到0.1mm。在专用脱棒机上脱棒,管材表面无压痕等缺陷,同固定芯头相比,拉拔力可降低25%左右,比游动芯头降低拉拔力5% ̄10%,变形区内轴向拉应力也可大大降低,因此,道次延伸系数高达2.9左右。 相似文献
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《Journal of Materials Processing Technology》2014,214(1):29-35
A superplastic dieless drawing process that requires no dies or tools is applied to the drawing of a Zn–22Al superplastic alloy for noncircular microtubes such as square, rectangular and noncircular multi core tubes having square inner and rectangular outer cross-sections. In this study, the effects of heating condition, such as heating length and the use or nonuse of cooling device, on deformation behavior are investigated. As a result, a square microtube with 0.58 mm side and a rectangular microtube of 0.75 mm × 1.3 mm were fabricated after 3-pass superplastic dieless drawing. In addition, the fundamental deformation behavior of noncircular tubes combined with square and rectangular tubes during the dieless drawing process has been clarified experimentally. The cross-sectional shape of the noncircular tubes after the superplastic dieless drawing process tends to be maintained on the basis of the similarity law in case of a wide heating length compared with a narrow heating length. Furthermore, a noncircular microtube, which has inner square tubes with a 335 μm side, and an outer rectangular tube of 533 μm × 923 μm were fabricated successfully after a 4-pass superplastic dieless drawing process. Consequently, it was found that the superplastic dieless drawing is effective for the fabrication of noncircular multicore microtubes. 相似文献
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Yong Tang Long-sheng Lu Dong Yuan Qing-hui Wang Xiao-lin Zhao 《Journal of Materials Processing Technology》2009,209(12-13):5333-5340
Miniature inner grooved copper tubes (mIGCT) which have an outer diameter less than 6 mm are in demand for the production of heat pipes. In this work, it is proposed to manufacture such tubes by a multi-stage tube sinking process with an initial mIGCT having an outer diameter of 6 mm. A FEM simulation approach is used to analyze stress, strain and damage distribution for the proposed process. For comparison, a smooth copper tube is also used in the simulation study. Furthermore, experiments are conducted to investigate plastic deformation of the grooves and teeth of the tube. Results show that the maximum stress and strain are occurred at the grooves area, while the maximum damage is located at the top of the teeth. The ratio of groove width to tooth width (β) is reduced after each drawing pass. Bonding, folding and segmenting, which represent potential flaws, have also been observed in the multi-stage tube sinking process, and are discussed. 相似文献
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The aluminium tubes with high strength and smooth outer-surface can be produced by non-mandrel drawing process. It is an effective method to study forming mechanism of drawing process by simulation, based on which the relevant dies with reasonable dimensions can be designed to ensure tube precision. The dynamic model and elasto-plastic finite element model of the forming process were established based on FEM software Deform-3D, then the simulation was performed. The expressions about drawing load were deduced, and the influence of friction coefficient on drawing load was computed by the expressions and software respectively. Based on simulation results the deformation mechanism of drawing process without plug was expounded. According to flowing speed vector graph the law of material flowing was summarized, by which the deformation regions were partitioned. Furthermore, some potential problems of drawing process such as diameter shrinking, thickness varying were forecast and analyzed quantificationally. 相似文献
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Forming method of axial micro grooves inside copper heat pipe 总被引:1,自引:0,他引:1
The high-speed oil-filled ball spinning and drawing process was put forward to manufacture the axially grooved heat pipe with highly efficient heat-transfer performance, and the forming mechanism of micro-grooves inside the pipe was investigated. The key factors influencing the configurations of micro-grooves were analyzed. When the spinning depth varies between 0.4 mm and 0.5 ram, drawing speed varies from 200 mm/min to 450 mm/min, rotary speed is beyond 6 000 r/min and working temperature is less than 50 ℃, the grooved tubes are formed with high quality and efficiency. The ball spinning process uses full oil-filling method to set up the steady dynamic oil-film that reduces the drawing force and improves the surface quality of grooved copper tube. 相似文献
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简要叙述了钢管拉拔过程的数值模拟现状和发展趋势;介绍了三维弹塑性有限元理论和相似理论在钢管拉拔过程数值模拟中的应用,及钢管拉拔CAD系统的开发情况;对钢管拉拔过程数值模拟的研究方向提出了看法。 相似文献
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利用非线性有限元仿真软件MARC,研究了外螺旋凸筋管成形过程的三维弹塑性有限元模拟技术.对外螺纹铜管的拉深成形过程进行了模拟,得到了成形过程中工件内部的应力和应变分布规律.结果表明,拉拔过程中,管料发生轴向延伸,但各部分延伸量不均匀,最大延伸变形发生在筋底中心部分.在周向,整体上管料发生压缩变形,但在筋底部分产生一定的延伸,应变为正;径向发生压缩变形.在定径区及铜管离开定径区后,轴向应力均为拉应力,但沿壁厚分布不均匀;同样,拉拔周向应力沿壁厚方向也呈不均匀分布,出定径区后在筋底区的外表面为负,内表面为正. 相似文献