半球形拉深件成形研究

本文对半球形拉深件进行了应力分析,推导出每一瞬时的应力公式,并进行了实验验证。此外。还对平球形拉深件成形过程中出现的问题作了讨论,并提出了几种解决办法。     

铝合金复杂曲面薄壁件液压成形技术

介绍了适合于制造铝合金复杂曲面薄壁件的液压成形技术,包括充液拉深、可控径向加压充液拉深和液体凸模拉深。由于充液拉深能提高成形极限,适合于制造铝合金复杂型面零件。可控径向加压充液拉深通过径向压力向内推料,进一步提高了成形极限,适合于成形大高径比筒形件。液体凸模拉深适合于获得深度较大、形状复杂、尤其底部具有小过渡圆角的复杂形状零件。     

DDCAD系统成形工艺分析模块(一)——任意形状轴对称拉深件的变形分析

介绍了DDCAD工艺设计于系统成形工艺分析模块中的拉深件的应变分析,为拉深工艺设计提供了重要的依据。     

直通型精细深拉深小件的统一研究--深拉深实验平台

根据直通型精细深拉深小件的工艺特点,提出并实现了一个深拉深实验平台,在这个基础上,推出了材料为430不锈钢、304不锈钢、1050(1060)合金铝、3003合金铝,且形状各异的大量深拉深件.     

DDCAD系统成形工艺分析及设计模块(二)——应变失稳判据成形极限方程

介绍了DDCAD系统工艺设计子系统中应变失稳判据——成形极限图(FLD),在对任意形状的轴对称拉深件进行应变分析的基础上,结合成形极限图(FLD)进行失稳判断,从而进行拉深工艺设计.     

一种有效提高拉深成形性能的方法

提出了一种能有效减小拉深件最大厚度变薄量 ,提高拉深成形极限及拉深件质量的夹紧式拉深模具结构 ,并已用于实际生产中。叙述了该模具结构特点及其工作原理 ,对有关工艺参数的影响进行了实验研究 ,并对实验结果进行了分析。     

筒形件反拉深数值模拟的关键技术

结合对Numisheet’99标准考题的模拟研究，论述了反拉深成形过程有限元模拟的关键技术问题，涉及反拉深成形过程的强化模型、接触、起皱、破裂及回弹计算等，并介绍主要模拟结果。     

盒形件多点常力压边拉深模设计

对盒形件拉深成形 ,提出了在周向多个位置施加压边力的方法 ,且根据常力压边原理 ,用弹簧和橡胶作弹性元件 ,可根据需要在不同位置施加不同的压边力 ,且每个位置的压边力在拉深过程中保持定值。以此设计的模具所提供的压边力 ,更适合复杂零件的成形 ,也更符合拉深工艺对压边力的要求     

研究拉深成形过程中的摩擦系数分布

主要介绍利用探针和传感器测定拉深过程中摩擦系数的实验方法,据此获得变形区内摩擦系数的分布情况.该方法有助于进一步分析板材在拉深成形过程中的摩擦和润滑情况.同时对计算机数值模拟金属板材在拉深成形过程中,如何确定摩擦系数边界条件提供了一种实验方法.     

拉深分区的计算机判定CAD系统

在盒形件拉深的毛坯设计和工艺设计中首先需要判定零件在盒形件拉深分区中的位置。在建立盒形件拉深系统的过程中 ,建立了拉深分区的计算机辅助判定系统 ,包括分区判定的数学模型的建立和软件程序的编制 ,并给出了判定实例。     

半球形件粘性介质压力成形的数值模拟研究

粘性压力成形技术是金属板材成形领域里新近出现的一种先进的加工工艺。对双面施放粘性介质的板材胀形进行了模拟研究 ,在双面施放介质的板材粘性介质胀形时 ,排放孔位置分布对毛坯成形过程有明显的影响。排放孔位置分布的不同造成模腔内介质的速度场不同 ,进而导致板材不同部位的流动速度的方向大小发生变化 ,最终使成形件的厚度分布不同     

整流器成形工艺和模具设计

球形件成形中最困难的问题是口部起皱和底部破裂 ,通过制订合理的成形工艺 ,将变形量分解和降低到最小程度 ,巧妙地解决了球形件成形中的难题。     

研究单位压边力值对板料成形性能的影响

主要介绍板料在拉深成形过程中单位压边力值对板料成形性能的影响。研究方法采用仿真技术 ,指出板料在成形过程中如按最初设定的单位压边力值进行成形 ,那么 ,板料成形过程中单位压边力值将逐渐增大 ,严重影响板料成形极限。如果采用控制板料在成形过程中压边圈下坯料的单位压边力值 ,将提高板料成形极限。其结论为生产现场提高板料成形性能和表面质量提供了一种可实施的方法。     

利用塑性介质挤胀成形三通管接头变形力的研究

此文对利用塑性介质挤胀成形三通管接头变形力进行了实验研究。设计了一套挤胀成形三通管接头的通用装置,并利用此装置进行了三通挤胀成形实验。此研究给出了影响成形过程的一些重要参数。将理论结果与实验结果进行了对比,两者吻合较好。     

Optimal and Robust Design of the Laser Forming Process

The laser forming process of sheet metal has been extensively analyzed, but few attempts have been made in the area of process design. The task of the process design in the laser forming of sheet metal is to determine a set of parameters, including laser scanning paths, laser power, and scanning speed, given a prescribed shape. Response surface methodology is used as an optimization tool. The propagation of error technique is built into the design process as an additional response to be optimized via desirability function and hence make the design robust. Focusing on a class of shapes, the design scheme is applied progressively in four cases in which issues such as a large number of design variables are properly addressed.     

External force-assisted laser forming process for gaining high bending angles

Laser forming process is used in forming and bending of metallic and non-metallic sheets. Laser beam irradiation causes a localized temperature increase and a localized mechanical strength decrease. In this article, an external mechanical force is added to a laser beam irradiation, which is called external force-assisted laser forming process, to gain a 90-degree bending angle. Furthermore, Numerical simulation of the process is performed to achieve a good understanding of the process. Simulation results show that more than two-third of the final forming is due to the laser beam irradiation. Equivalent plastic strain values during laser forming and external force-assisted laser forming processes are compared. Results show that equivalent plastic strain in laser forming process increases in a step pattern, with increasing in scan pass numbers. This occurs because when the laser beam irradiates on the sheet surface, it reduces the yield strength of the sheet. Equivalent plastic strain in external force-assisted laser forming process has an oscillatory step nature. This attributes to simultaneous effects of strain hardening and thermal induced reduction of yield strength of the sheet. Simulations were in good accordance with experiments.     

Bending of Titanium Sheet Using Laser Forming

Laser forming, a novel manufacturing method for bending sheet metal first reported in 1985, has been investigated as an alternative to hot brake forming (industry standard) of titanium sheet parts for the aircraft industry. Laser forming involves scanning a focused or partially defocused laser beam over the surface of a titanium workpiece to cause localized heating along the bend line and angular deflection toward the beam. The main advantage that laser forming has over conventional brake forming is increased process flexibility. An experimental investigation of this process (primarily designed experiments) met the following objectives: identified the response variables related to change in geometry (bend angle) and material microstructure; characterized the influence of process variables (scanning speed, beam diameter, laser power) on these response variables; determined the degree of controllability over the process variables; and evaluated the suitability of laser forming for the aircraft industry (most important), all with respect to titanium sheet. It has been determined that laser forming with an Nd:YAG laser is a controllable, flexible manufacturing process for titanium sheet bending. Unfortunately, these advantages over traditional hot brake forming are overshadowed by the fact that, with regard to forming with titanium, laser forming is significantly slower and more labor and energy intensive, and results in unacceptable material properties at the bend line according to aircraft industry standards. These findings cast doubt over the assertions of some researchers that laser forming may be a viable manufacturing process for parts made in small batches. Instead, it appears that it may be best suited for rapid prototyping of sheet metal parts.     

LYl2半球形件拉深成形过程的动力显式有限元模拟

基于连续介质力学及有限变形理论 ,建立了用于三维板料成形过程模拟的有限元模型 ,开发了动力显式算法的板料成形过程模拟的有限元分析程序DESSFORMM3D。最后 ,用笔者新开发的动力显式弹粘塑性有限元程序对不同压边情况下半球形件的拉深过程进行分析 ,并把数值结果与实验进行对比 ,验证了软件的计算结果。     

成形工艺对轿车减振器座应变状态影响的研究

通过网格应变分析技术 ,对某轿车采用一次成形、两次成形工艺冲制减振器座的应变状态进行了定量研究 ,结果表明 ,成形工艺对减振器座的应变分布、应变路径、应变大小影响很大 ,一次成形较两次成形对材料的成形性能要求较高 ,两次成形工艺更有利于零件成形     

对金属薄板成形性试验方法(HB6140.4-87)中弯曲凸模的探讨

金属板材成形性试验方法 (HB61 4 0 .4- 87)是测定各种成形工艺参数的重要依据 ,但在应用该标准进行试验研究过程中 ,发现弯曲试验部分所规定的弯曲凸模形状和尺寸不能很好地满足试验原理的要求。在深入研究的基础上指出了问题所在 ,并提出了建议性的设计修改意见 ,这对完善标准内容、提高材料成形试验研究水平和更准确地指导生产实践有着重要的现实意义。