特大型水电台阶法兰锻件工艺技术

Process technology on extra-large hydropower stepped flange forgings

4160 mm特大型水电台阶法兰锻件的吨位重、规格大、法兰直径及相邻截面差大,采用传统的芯棒直接卡台+分段扩孔成形法很难保证最终成形尺寸。通过综合分析特大型水电台阶法兰类锻件的关键成形方法和控制难点,创新锻造工艺,首次提出了"实心制坯+分段扩孔成形"的控制新方法;确定实心制坯环节采用带钳把卡台锻造,且下料后增加平整端面工序,分段扩孔环节的压下量按照30~45 mm控制,且每火次扩孔后增加收孔工序;并结合工艺性分析,建立了塑性有限元和结构有限元分析模型,仿真并分析了实心制坯和分段扩孔过程的金属流动规律、金属流动速率及各部位的金属流动速度差,预测了新方案的工艺参数和过程控制,以及实心制坯、分段扩孔的成形效果和质量。通过生产试制,验证了该工艺参数及成形工艺的合理性。

The extra-large hydropower stepped flange forgings with Ф4160 mm have heavy tonnage,large specifications,large flange diameter and difference in adjacent cross-sections,and it is difficult to guarantee the final sizes using traditional method of ingot blanking,mandrel drawing with clamping table and reaming. Therefore,a new control method of"solid step billet + stepped reaming"was proposed for the first time by comprehensive analysis of key forming methods and control difficulties of the extra-large hydropower stepped flange forgings to innovate the forging process,it was determined that the solid billet was forged on the clamping table with pliers,and then the flattening process of end surface was added after blanking. In addition,the reduction of stepped reaming was controlled between 30 and 45 mm,and the hole shrinkage process was added after reaming for each fire. Combined with the process analysis,the analysis models of plastic finite element and structural finite element were established,and the metal flow laws,the metal flow rate and the metal flow velocity difference of each part for solid billet and stepped reaming were simulated and analyzed to predict the new process parameters,the process control,the effect and quality of solid billet and stepped reaming. At last,the rationality of process parameters and forming process were verified by production test.