关键参数对薄壁筒形件充液成形的影响规律

为了研究初始反胀高度(IRBH)、反胀压力(IRBP)和液室压力加载路径3个工艺参数对板料充液成形的影响规律,以不锈钢321材料为研究对象,进行板材充液成形工艺过程的分析。首先,利用数值模拟的方法,在有初始反胀(IRB)的充液成形基础上,研究了初始反胀高度与初始反胀压力的组合形式以及液室压力加载路径对制件成形的影响规律,然后分别研究了有无初始反胀的充液成形过程。最后,通过实验的方法进行验证。结果表明:当初始反胀高度为3.75 mm、初始反胀压力为2 MPa时,充液结束时板料的最大减薄率为4.803%,在所有结果中最小;无初始反胀时,零件壁厚最大减薄率为5%;当在充液拉深后期继续加大液室压力时,板料底部发生波动,出现二次变形,与此同时,板料最大减薄率增大。从而验证了合适的初始反胀高度和反胀压力可以减小制件壁厚的最大减薄率,液室压力加载路径不同,零件的壁厚分布也不同。

Influence of key process parameters on thin-wall tube workpiece in hydroforming process

In order to research the influence of initial reverse bulging height ( IRBH) , reverse bulging pressure ( IRBP) and cavity pres-sure loading paths on the hydroforming process of sheet, for the stainless steel 321, an analysis of the hydroforming process of sheet metal was carried out. Firstly, the influences of the IRBH, IRBP and the cavity pressure loading paths on the forming of part were studied by the method of numerical simulation and based on the hydroforming with initial reverse bulging ( IRB) . Secondly, the hydroforming proces-ses with and without IRB were discussed. At last, they were confirmed by the experiment. The results show that when the IRBH is 3. 75 mm and the IRBP is 2 MPa, the maximum thinning rate of sheet is 4. 803% in the end of hydroforming process which is the smallest value in all the results. While the hydroforming process is without IRB, the maximum thinning rate is 5%. However, when the cavity pressure increases continual during the later stage of hydro-mechanical deep drawing, the bottom of sheet metal is fluctuating and there is a double-dip deformation on the sheet metal. At the same time, the maximum thinning rate of sheet increases. Thus, it is verified that the maximum thinning rate of wall thickness decreases effectively adpting appropriate IRBH and IRBP, but when the cavity pressure loading path is different, the distribution of wall thickness is different too.