方盒形件混合分块压边拉深成形工艺研究

发布时间：2018-02-19 19:40

本文关键词： 拉深成形方盒形件径向分块压边混合分块压边起皱　出处：《燕山大学》2016年硕士论文　论文类型：学位论文

【摘要】：起皱和破裂是拉深成形中最常见的两种缺陷。在拉深过程中,压边力参数对制件能否顺利成形起着重要作用,在不同的变形位置和不同的变形区域所需要的压边力也是不同的,较小的压边力容易使板坯产生起皱失稳,较大的压边力则会使板坯的破裂趋势增大,降低成形极限。在板材成形领域,近二十年来,压边力控制方法及其相关技术一直是人们的研究热点和技术难点之一。混合分块压边方法是针对盒形件的拉深成形而提出的,即在拉深过程中对法兰直边区和法兰圆角区沿周向分块压边,而在法兰圆角区又采用径向分块压边。针对这种压边力控制方法的分块方法、分块位置、各区域之间的压边力比值等参数对拉深成形过程的影响规律,以及工艺实施方法等问题进行了研究。首先,采用有限元模拟方法,对方盒形件的拉深成形过程混合分块压边方法的分块位置、压边力比值等对拉深成形过程的影响进行了分析,优化确定压边圈几何参数和压边力参数。采用混合分块压边方法,将法兰区的压边圈分为16块,其中直边区4块,圆角区12块。分块的原则是按厚度梯度分布规律确定。针对所研究的成形制件,直边区域与圆角区域压边力最佳比值为0.9:1,圆角区内、中、外三个压边块对应区域的压边力最佳比值为1:1.69:0.46。然后,采用有限元分析方法研究了方盒形件分别在整体压边、混合分块压边和周向分块压边等工艺条件下的拉深成形过程。研究结果表明,在其他工艺条件相同的情况下,方盒形件的最大成形高度、厚度分布均匀性、最大拉应力、起皱失稳情况,以及成形极限等,都能得出混合分块变压边力方法成形效果优于其他压边方法,整体压边方法成形效果最差。最后,研制了方盒形件拉深成形实验系统,包括拉深实验模具和变压边力控制系统。实验模具中的压边圈采用上下双层结构设计,上层在直边区和圆角区分块,以对板坯分别进行压边,下层起支撑作用。直边部分和圆角部分分别由两套独立的液压系统进行变压边力控制。实验结果表明,该实验系统可以较好地实现方盒形件的混合分块压边方法,完成拉深成形过程。
[Abstract]:Wrinkling and cracking are the two most common defects in deep drawing. In the process of drawing, the parameters of blank holder force play an important role in the smooth forming of the parts, and the blank holder forces required in different deformation positions and different deformation regions are also different. A small blank holding force can easily wrinkle and destabilize the slab, while the larger blank holder force will increase the cracking tendency of the slab and reduce the forming limit. In the field of sheet metal forming, in the past twenty years, The control method of blank holding force and its related techniques have been one of the hot and technical difficulties. The mixed block blank holder method is proposed for the deep drawing of box-shaped parts. In the process of drawing, the straight flange and flange fillet are cut in the circumferential direction, and the radial block is used in the flange corner. The influence of the parameters such as the ratio of blank holder force between different regions on the forming process and the process implementation are studied. Firstly, the finite element method is used to simulate the process. In this paper, the effects of the block position and the ratio of the blank holder force on the forming process are analyzed, and the geometric parameters of the blank holder ring and the parameters of the blank holder force are optimized. The blank holder ring of flange area is divided into 16 blocks, including 4 straight edges and 12 round corners. The principle of dividing the flange is to determine the thickness gradient distribution law. The optimum ratio of blank holding force in straight edge region to round corner region is 0.9: 1, and the optimum ratio of blank holder force in the corresponding region of three blank holder blocks in circular corner region is 1: 1.69: 0.46.Then, the finite element analysis method is used to study the integral blank holder of square box parts. The results show that the maximum forming height, thickness distribution uniformity and maximum tensile stress of the square box are obtained under the same process conditions, such as mixed block blank pressing and circumferential block blank pressing, and the results show that the maximum forming height, thickness distribution uniformity and maximum tensile stress are obtained under the same conditions of other process conditions, such as the maximum forming height, the thickness distribution, the maximum tensile stress, and so on. In the case of wrinkle instability and forming limit, it can be concluded that the forming effect of the mixed block variable blank holder method is better than that of other blank holder methods, and the integral blank holder method has the worst forming effect. Finally, an experimental system for drawing forming of square box parts is developed. The blank holder in the experimental die is designed with upper and lower double layer structure, and the upper layer is in the straight edge area and the obliquely separated block, so that the slab can be blanked separately. The lower layer plays a supporting role. The straight edge part and the circular corner part are controlled by two sets of independent hydraulic systems, respectively. The experimental results show that the experimental system can achieve the mixed block blanking method for square box parts. Complete the drawing process.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG386

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