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对T2紫铜箔板进行电磁微成形实验,研究不同模具结构对材料成形性能的影响.采用激光共聚焦显微镜及轮廓仪研究不同模具结构对箔板电磁微成形的影响规律,分析模具结构对材料流动规律的影响.研究结果表明:随着电压的升高坯料出现不同程度的翘曲现象,采用凸型模具更有利于凹模内气体的排除,使得坯料能够迅速贴模;随着电压的升高材料成形性不断提高,采用凹型模具比采用凸型模具更加有利于微槽精度的提高;电磁成形制件应变分布均匀,凸型模具成形制件壁厚最小值出现在微槽侧壁,成形过程以拉深成形为主;凹型模具成形制件最小壁厚出现在微槽底部,成形过程以胀形为主. 相似文献
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《中国材料进展》2016,(4)
针对大型铝合金曲面件电磁渐进成形技术,采用整体压边和分块变压边力压边的方式,研究了电磁渐进成形工艺中首次放电后板料的起皱现象和规律,揭示了压边力对电磁渐进成形首次放电过程中板料起皱和材料塑性流动行为的影响。结果表明:数值模拟结果预测出的首次放电后易起皱区域为板料的法兰区和悬空侧壁区,与实验结果一致;整体压边方式下法兰区域和悬空侧壁区域无起皱的临界压边力分别为8.4 kN和21.6 kN;分块变压边力方式下,最靠近局部塑性变形区的压边分块上的法兰区域无起皱临界压边力为8.4 kN,最靠近悬空区的对称的两个压边分块上的悬空侧壁区域无起皱临界压边力为23.8 kN,且相比于整体压边方式的无起皱临界条件下,在分块压边方式的无起皱临界条件下板料的变形流动能力得以明显提高。 相似文献
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目的 解决大截面铝合金带筋方筒构件在反挤压过程中成形力大的难题,实现在3 000 t压力机下成功制备内孔为665 mm×665 mm的大截面带筋方筒形构件。方法 提出了一种使用新型棱台凸模结构代替平凸模结构的方法,用主应力法得出了棱台凸模结构与平凸模结构的挤压力计算公式,对比分析了2种凸模结构反挤压成形力的大小,并用DEFORM有限元软件模拟分析了不同结构参数下的棱台凸模反挤压过程,最终进行工程试制,验证了反挤压工艺的可行性。结果 通过主应力法得出了方筒形件的变形力计算公式,得出棱台凸模结构反挤压成形力小于平凸模结构反挤压成形力,经模拟分析得出在反挤压过程中棱台凸模结构的最优结构参数为棱台斜角15°、棱台高度40 mm,并在3 000 t压力机上成功制得内孔为665 mm×665 mm的大截面带筋方筒形构件。结论 通过数值模拟分析可知,与采用平凸模结构相比,采用棱台凸模结构时的反挤压成形力降低了约13%,同时减少了挤压变形过程中的金属流动“死区”。经实验验证,在3 000 t压力机上成形了内孔为665 mm× 665 mm的大截面带筋方筒形构件,实现了省力挤压。 相似文献
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目的 研究不同冲头刃口形状对冲裁变形过程和冲头磨损情况的影响。方法 采用有限元方法和实验分析了相同工况下平冲头、台阶状冲头和屋顶状冲头对坯料冲断行为的影响,以及不同刃口形状的冲头在冲裁后的磨损情况。结果 冲头结构的改变使冲裁过程发生了变化,影响了冲裁时坯料内部的应力–应变分布、峰值冲裁力、裂纹扩展速度、弹性应变能和冲头单次磨损深度。屋顶状冲头在冲裁时峰值冲裁力最低,较平冲头与台阶状冲头的峰值冲裁力分别降低了15%、10%,坯料最早起裂,也最快完成断裂,坯料的高应力区域集中在凹模刃口,且该冲头冲裁时坯料内储存的弹性应变能最多,冲头工作区的单次磨损深度最小,较平冲头与台阶状冲头的单次磨损深度分别降低了84%、80%。结论 屋顶状冲头使坯料在断裂前发生了更大的拉伸变形,储存了更多的弹性应变能,坯料在拉伸状态下发生了剪切变形,冲裁力更小,高应力分布的改变降低了冲裁时坯料对冲头侧面的压力,冲断后的坯料发生弹性恢复,可防止冲头回程时坯料抱紧冲头造成的二次磨损。 相似文献
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为实现直齿圆柱齿轮精密成形,并克服传统工艺存在的成形力大、模具结构复杂等一些不足,在已有齿形凸模双向镦挤成形直齿圆柱齿轮的基础上提出了另外2种改进的成形工艺,分析了不同成形工艺下端面摩擦力对载荷的影响,利用有限元模拟软件DEFORM-3D分别对3种成形工艺进行了数值模拟研究,并提出了一种优化的成形新工艺——无齿凸模双向镦挤精密成形.结果表明:采用无齿凸模镦挤成形直齿圆柱齿轮在载荷及模具结构方面优于有齿凸模镦挤成形,其中,无齿凸模双向镦挤较有齿凸模双向镦挤,上、下凸模载荷下降约55%;无齿凸模双向镦挤较非对称凸模双向镦挤,上、下凸模载荷分别下降约50%、38%;无齿模具加工制造更容易,强度更高;新工艺的等效应力最大值为3种方案中最小,而且等效应力变化正常,无破坏现象出现.对优化后的成形工艺进行了试验研究,得到了齿形轮廓清晰、充填饱满、无折叠、开裂等缺陷的铅质试件,试验结果与模拟结果基本吻合. 相似文献
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通过对2号药模底座的化学成分分析、断口宏微观形貌观察、金相组织检测、硬度检测及药模底与压药冲子的配合间隙检查,得出药模底座断裂的性质为脆性断裂;药模底座R角交接处粗大的加工刀痕,R角过渡不圆滑是药模底座断裂的主要原因;磨削不当产生了二次淬火马氏体,使得药模底座底部的组织脆性增加、应力增强,是药模底座断裂的重要原因;材质不良对药模底座的断裂也有重要影响;压药冲子与药模底座之间的配合间隙过小,导致压药冲子与药模底座间产生较大应力集中,也是药模底座断裂不可忽视的因素。 相似文献
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The adhesion work of thin film, such as membrane, can be measured by pull-off test. In this kind of experiments, the residual stress in film due to pretension during sample preparation plays an important role in experimental results. Moreover, the effect of residual stress on results varies greatly depending on different punch shapes. The coupling effect of punch shape and residual stress is studied in the framework of plate theory and energy principle. The analytical expressions for the effect parameters are obtained on the basis of the energy criterion. From our study, it is found that the effect of residual stress is more significant for a circular punch than the one for a rectangular punch. For future pull-off experiments, the coupling effect should be taken into account and the rectangular punch instead of a circular punch should be prioritized in experiments to mitigate the effect of residual stress. 相似文献
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B. L. WANG J. C. HAN S. Y. DU 《Fatigue & Fracture of Engineering Materials & Structures》2011,34(2):139-148
The problems of a surface electrode and a rigid punch on a finite piezoelectric layer are considered in this paper. The resultant force and the accumulated electric charge on the electrode/punch are prescribed. Closed‐form solutions for the electromechanical fields at the electrode/punch tip are obtained and are expressed in terms of the applied strain and electric field intensity factors. For infinite layer thickness, the strain and electric field intensity factors are obtained in closed‐form. For finite layer thickness, the strain and electric field intensity factors are obtained numerically by the singular integral equation technique. The effect of layer thickness on the electrode/punch tip fields is discussed. It is found that the field intensities at the electrode/punch tip can be reduced considerably by decreasing layer thickness. In addition to the single electrode/punch problem, this paper also provides a solution technique for two collinear surface electrodes/punches on a finite piezoelectric layer. The effect of the relative distance between the two electrodes/punches on the electromechanical fields in the piezoelectric layer is also discussed. 相似文献
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目的研究超高强度钢DP1000液压成形A柱仿真技术和试验效果,解决批量生产中DP100焊管技术和同步冲孔等关键技术。方法基于Autoform有限元模拟软件,仿真分析了DP1000液压成形A柱的可行性,试验了DP1000液压成形A柱零件。通过对比高频焊管和激光焊管的液压成形零件焊缝质量,解决量产零件开裂问题,开展了DP1000液压成形A柱的Cr12MoV、ASP30和SKH51不同材料的同步冲孔效果,解决DP1000材料冲头寿命和冲孔质量问题。结果采用DP1000材料可以获得液压成形A柱,具有制造可行性。与高频焊管相比,具有较小的热影响区和硬度变化较小的激光焊管,更适合DP1000液压成形A柱使用。结论 ASP30和SKH51比传统的Cr12MoV更适合于DP1000材料液压成形A柱同步冲孔,冲头寿命提高80多倍,冲孔质量良好。 相似文献
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The effect of different punches head profile on deep drawing of 5005 H34 Aluminium circular blanks to manufacture a cup-shape product were studied. Experiments were conducted by a 150 ton hydraulic press with using different punches geometry and lubricants viscosity. The drawing force, blank holder pressure, and movement of the punch were measured during experiments to monitor effects of various manufacturing parameters during the drawing process. The surface finish and dimensions of all cups were determined after drawing processes. The geometry of the punch influences the friction force between the blank and punch, and consequently the stretching bottom surface of the cup. The Flat punch geometry produced cups with better surface finish, higher drawing force, and thinner cup wall thickness in comparison to other punches geometry. The Bore punch geometry enhances the stretching of the bottom part of the cup. The presence of lubricant in the process improves the stretching of bottom part of a cup for all punches profile. 相似文献
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Davar Khossravi 《Drug development and industrial pharmacy》1999,25(8):885-895
The consolidation behaviors of various pharmaceutical solids were characterized by investigating the relationship between the calculated hysteresis areas and the maximally applied punch pressures. An Instron universal testing apparatus and an instrumented die were used to generate compression cycle profiles at various maximally applied punch pressures for the materials studied. Based on the profiles obtained, hysteresis areas were calculated for the materials studied as a function of maximally applied punch pressures. Furthermore, model profiles describing the plastic and brittle fracture processes were utilized to derive mathematical relationships between the calculated hysteresis cycle areas and the maximally applied punch pressures. The mathematical relationships derived indicate that a linear relationship between hysteresis areas and maximally applied punch pressures exists for plastic materials, whereas for brittle materials the hysteresis areas are related to the square of the maximally applied punch pressures. Experimental data obtained support the mathematical relationships derived. The goodness of fit to the models derived is used to rank order the consolidation mechanism of various drugs and pharmaceutical excipients. 相似文献
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The dynamic contact problem for a homogeneous, isotropic elastic half-space and a punch of an arbitrary base shape is studied. During the motion of the punch it is assumed that the contact area is fixed and there is no friction under the punch. An approximate solution to the problem is obtained under the assumption that the contact pressure under the punch is slightly varied during the time of travel of the Rayleigh wave along the distance equal to the diameter of the contact area. The solution of the problem of slow motions of a punch on an elastic half-space is reduced to the solution of the recurrent system of integral equations of the static contact problem. Asymptotic models of vertical motions of a flat-ended punch with an arbitrary base are constructed. The case of an elliptic punch is considered in detail. 相似文献