瞬态粘性介质柔性冲头金属薄板超声微拉深成形工艺研究

发布时间：2018-01-31 18:29

本文关键词： 超声振动金属薄板粘性介质柔性冲头微成形工艺参数　出处：《深圳大学》2017年硕士论文　论文类型：学位论文

【摘要】：瞬态粘性介质柔性冲头金属薄板超声微成形工艺是一种新型的微成形工艺。该成形工艺利用熔融塑料形成的柔性冲头代替传统的刚性冲头,避免了刚性冲头不易加工及与凹模精确对中较为困难等缺点,同时该成形工艺将超声振动与粘性介质进行了有机的结合,使得该工艺同时具备粘性介质成形和超声成形的优点。一方面,粘性介质柔性冲头传递冲压力更均匀,能推迟材料颈缩、提高材料成形极限;另一方面,超声振动通过柔性冲头传递到坯料和模具上,减小了坯料与模具之间的摩擦力、降低了坯料的流动应力。本文在课题组前期工作的基础上进一步的研究了超声微拉深时工艺参数对制件成形性能的影响。本文主要内容包括:(1)前期研究中,针对拉深过程中坯料成形左右不对称的问题设计了一套固定压边间隙的实验装置。由于原实验装装置的间隙值不可调,导致拉深制件仍出现成形左右不对称、破裂或复制度低等缺陷,因此在前期研究的基础上重新设计并加工了一套实验装置。该实验装置可以实现压边间隙的平衡与大小的调节,为进一步探究压边因素对拉深成形的影响奠定了基础。(2)为了精确的测量出上述装置的压边间隙,提出了一种新的测量方法。在一定压力下对塑料粉末施加超声振动,使塑料粉末在超声振动的激励下升温而熔融成具有流动性能的粘性介质,并充满整个间隙空腔,然后测量冷却后的介质外形从而间接获得压边间隙值。用该方法测得实验装置调节出的压边间隙范围为0~35μm,与计算结果对比得出测量的平均误差为±0.6μm,局部误差为±1.5μm。(3)以退火后的T2紫铜薄板为坯料,应用该工艺对其进行微拉深实验。分析了气缸压力、压边间隙、超声振幅等参数对制件成形质量的影响。实验结果表明,在一定实验条件下,制件的复制度与气缸压力、超声振幅成正比。气缸压力和超声振幅越大复制度越高,当气缸压力为0.1MPa、超声振幅为30.0μm时,制件的复制度可达86.4%;通过对拉深件壁厚变化规律的研究发现,由于粘性介质柔性冲头的特殊性,制件侧壁上部受到的应力最小,中心位置在拉深过程中受到应力最大,导致制件的侧壁上部厚度增加量最多,约为17.6%,而在底部中心位置附近制件厚度最小,厚度减小了约14.4%,所以中心位置附近是拉深时最容易被拉破的危险部位。
[Abstract]:Ultrasonic microforming of metal sheet with transient viscous medium flexible punch is a new microforming process, which uses flexible punch formed by molten plastics to replace the traditional rigid punch. The rigid punch is difficult to be machined and it is difficult to accurately align with the die. At the same time, the ultrasonic vibration is combined with the viscous medium organically. The process has the advantages of both viscous medium forming and ultrasonic forming. On the one hand, the impact pressure of viscous medium flexible punch is more uniform, which can delay the necking of the material and increase the forming limit of the material. On the other hand, ultrasonic vibration is transmitted to the blank and die through flexible punch, which reduces the friction between blank and die. The flow stress of the blank is reduced. Based on the previous work of the research group, the influence of the technological parameters on the forming properties of the workpiece during ultrasonic micro-drawing is further studied in this paper. The main contents of this paper are as follows: 1). In a preliminary study. In order to solve the problem of left and right asymmetry of blank forming in deep drawing, a set of experimental equipment is designed to fix the gap of blank holder. Because the gap value of the original experimental device can not be adjusted, the forming left and right asymmetries still occur in the drawing parts. Because of the defects of low degree of rupture or duplication, a set of experimental device was redesigned and manufactured on the basis of previous research, which can balance and adjust the size of the blank holder gap. For the further study of the influence of blank holder factors on drawing forming laid a foundation. 2) in order to accurately measure the blank holder clearance of the device. In this paper, a new measuring method is proposed, in which ultrasonic vibration is applied to the plastic powder under certain pressure, which causes the plastic powder to heat up under the excitation of the ultrasonic vibration and melt into a viscous medium with flowing property. And filled with the whole clearance cavity, then measured the shape of the medium after cooling, so as to indirectly obtain the blank holder clearance value. By using this method, the range of the blank holder gap adjusted by the experimental device is 0 ~ 35 渭 m. Compared with the calculated results, the average measurement error is 卤0.6 渭 m and the local error is 卤1.5 渭 m 路m ~ (3). The annealed T2 red copper sheet is used as the blank. The effects of cylinder pressure, blank holder clearance, ultrasonic amplitude and other parameters on the forming quality of the workpiece are analyzed. The experimental results show that under certain experimental conditions. The complex system is proportional to the cylinder pressure and the ultrasonic amplitude. The greater the cylinder pressure and the ultrasonic amplitude, the higher the reproduction degree, when the cylinder pressure is 0.1 MPA, the ultrasonic amplitude is 30.0 渭 m. The copy degree of the parts can reach 86.4%. Through the study of the variation law of the wall thickness of the drawing parts, it is found that due to the particularity of the flexible punch in the viscous medium, the upper part of the side wall of the workpiece is subjected to the minimum stress, and the center position is subjected to the maximum stress in the process of drawing. As a result, the upper thickness of the side wall increases the most, about 17.6, while the thickness of the workpiece near the center of the bottom is the smallest, the thickness of which is reduced by about 14.4%. So near the center is the dangerous part that is most easily broken when drawing deep.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG386.32;TG663

【参考文献】