5m直径大角度型材框拉弯成形工艺

针对某一运载火箭大角度型材框,对力控制模式下的拉弯成形进行了模拟及试验研究,模拟分析了拉弯力对成形件应力、应变分布及回弹量的影响规律。模拟结果显示,随着拉弯力增加,型材截面内外侧切向应力差减小,回弹和扭翘变形也减小,但不利的一面是变形量增大,零件壁厚减薄率增加,截面尺寸变化加大,综合考虑,选取合适的拉弯力为97.4 k N。试验分析了拉弯力、第1次拉弯包角及补拉量对零件成形精度的影响规律。试验结果表明,拉弯力和补拉量越大,零件的角度、平度及弧度间隙越小,尺寸精度越高。通过试验,得出了优化的拉弯工艺参数,即拉弯力为105 k N,第1次拉弯包角为65°,补拉量为60 mm。在此参数下拉弯,零件淬火后变形程度较小,扭翘现象较小,回弹量较小,成形出尺寸合格的零件。

Stretch-wrap bending of 5 m-diameter large angle profile frame

For the large angle profile frame of a carrier rocket,the stretch-wrap bending under the force control mode was simulated and experimented,and the influences of stretch-wrap bending force on stress,strain distribution and springback were simulated and analyzed.The simulation results show that the tangential stress difference between outside and inside of profile section decreases,springback and warping decrease with the increase of stretch-wrap bending force.However,the deformation,the thinning rate of wall thickness and the variation of cross-sectional dimension increase with the increase of stretch-wrap bending force.Considering all the above,the appropriate stretch-wrap bending force 97.4 kN is selected.And the influences of the stretch-wrap bending force,the first comer wrap and the amount of compensation on the accuracy of forming were analyzed by experiment.The results show that the larger the stretch-wrap bending force and the amount of compensation are,the smaller the angle,flatness and radian clearance of parts are,and the higher the accuracy of part size is.Thus,the optimized bending process parameters are attained by experiments with the stretch-wrap bending force 105 kN,the first comer wrap 65°and the amount of compensation 60 mm.Based on the above parameters,the qualified parts are formed with less quenching deformation,wist phenomenon and springback.