管坯中部镦锻成形规律实验研究

通过管坯中部镦锻的实验研究，观察到带芯轴支撑的管坯发生塑性变形时，其内壁沿轴向呈现四种典型的几何形状：直壁、单鼓形、多鼓形和折叠．利用圆环镦粗的数学解，对几何形状的成因作了定性分析，并从理论上简述了管坯中部镦锻的成形规律，给出了镦锻中部带法兰的管类零件应满足的聚集条件：当时，法兰可一次成形；当ｌｆ／ｗ＞３．６或时，需增加聚集工步．由此设计的空心抽油杆平锻模，在生产中获得了令人满意的结果．

On the Law of Tube Central-upsetting

Through expermental investigations of tube central-upsetting, it is revealed that four typical modes of defor-mation in the inner wall-straight wall. single drum, multi-drums and local folds-exist in the process of tublur plastic deformation with the support of the mandrel. The mathematical results in upset forging of rings are used for quantitatively analysing reasons of modes of deformation. The law of tube central-upsetting is then discussed theorically, and gathering conditions observed by tubular parts upsetting with centre-flange are presented: if lf/w < 3. 6 and df < (3d20- 2d2i)1/2, flanges could be formed once; If lf/w > 3. 6 or df > (3d2v-- 2d2i)1/2, gathering steps should be added. Upsetting dies for hollow rods are designed according to the above-mentioned conclusions and that are found to be satisfactory in production.