Abstract：Multi-ram forging is the main production process for large-diameter valves. However, premature cracking at the root of the punch and plastic deformation at the top of the punch are the main problems in the forging process with the punches often having short service lives. This study analyzes the forging process, especially the irregular metal flow that creates offset loading forces on the punch, which leads to punch failures. The low thermal resistance causes the plastic deformation at the top of the punch. This analysis optimizes the metal flow during the forging through die optimization to reduce the stress concentrations at the punch root by changing the joint between the punch and the press. The FGH96 super alloy is used to improve the deformation resistance at high temperatures. Optimization of the fillet radius in the mold and smoothing of the punch surface reduce the stress concentration at the joint to effectively reduce cracking. The stresses at the top of the punch are below the yield strength with the FGH96 super alloy so plastic deformation does not occur at the top of the punch. A horizontal punch made to forge a 3 inch (7.62 cm) valve body works very well with no cracks or deformation at the punch top for 100 cycles. The punch service life is then much longer.
胡福生, 张磊, 林峰. 大口径阀门阀体多向模锻成形的模具优化设计[J]. 清华大学学报（自然科学版）, 2016, 56(6): 646-649,655.
HU Fusheng, ZHANG Lei, LIN Feng. Optimal design of a multi-ram forging mold for large-diameter valve bodies. Journal of Tsinghua University(Science and Technology), 2016, 56(6): 646-649,655.
 任运来, 聂绍珉, 苗雅丽, 等. 多向模锻技术的发展及应用 [J]. 重型机械, 2014(4): 1-8.REN Yunlai, NIE Shaomin, MIAO Yali, et al. Development and application of multi-ram forging technology [J]. Heavy Machinery, 2014(4): 1-8. (in Chinese)
 林峰, 张磊, 孙富, 等. 多向模锻制造技术及其装备研制 [J]. 机械工程学报, 2012, 48(18): 13-20.LIN Feng, ZHANG Lei, SUN Fu, et al. Multi-ram forge process and its equipment development [J]. Chinese Journal of Mechanical Engineering, 2012, 48(18): 13-20. (in Chinese)
 郑彬彬, 董传勇, 薛克敏, 等. 三通阀体多向模锻工艺研究 [J]. 精密成形工程, 2010, 2(5): 61-63.ZHENG Binbin, DONG Chuanyong, XUE Kemin, et al. Study on multi-ram forging process of triple-valve body [J]. Journal of Net Shape Forming Engineering, 2010, 2(5): 61-63. (in Chinese)
 黄彩娥. 多向模锻的模具结构和设计 [J]. 金属成形工艺, 2000, 18(6): 28-45.HUANG Caie. Die construction and design of multiple-ram forging [J]. Metal Forming Technology, 2000, 18(6): 28-45. (in Chinese)
 YU Hongya, TANG Jiliang, TANG Yao, et al. Research on 800 MN hydraulic press monitoring system [J]. Material Research Innovation, 2015, 19(S6): 181-183.
 HUA Huaping, ZHOU Yin, LI Xinxing, et al. Variation of wear behavior of H13 steel sliding against different-hardness counterfaces [J]. Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2015, 229(6): 763-770.
 LIU Chang, REN Chengzu, WANG Guofeng, et al. Study on surface defects in milling Inconel 718 super alloy [J]. Journal of Mechanical Science and Technology, 2015, 29(4): 1723-1730.
 Ucun W, Irfan C. Effect of tool coating materials on surface roughness in micromachining of Inconel 718 super alloy [J]. Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2014, 228(12): 1550-1562.
 徐吉生. 等径三通多向模锻金属流动研究 [J]. 锻压技术, 2002(4): 11-13.XU Jisheng. Study on metal flow in mult-ram forging process of equal diameter tee joint [J]. Forging & Stamping Technology, 2002(4): 11-13. (in Chinese)
 Panin S V, Maruschak P O, Lyubutin P S, et al. Application of meso- and fracture mechanics to material affected by a network of thermal fatigue cracks [J]. International Journal of Fatigue, 2015, 76: 33-38.
 Caprioli D, Sara H. Short rolling contact fatigue and thermal cracks under frictional rolling: A comparison through simulations [J]. Engineering Fracture Mechanics, 2015, 141: 260-273.
 国为民, 董建新, 吴剑涛, 等. FGH96镍基粉末高温合金的组织和性能 [J]. 钢铁研究学报, 2005, 17(1): 59-63.GUO Weimin, DONG Jianxin, WU Jiantao, et al. Microstructure and properties of PM super alloys FGH96 [J]. Journal of Iron and Steel Research, 2005, 17(1): 59-63. (in Chinese)
 李福林, 付锐, 冯涤, 等. 镍基变形高温合金CDS&W FGH96热变形行为研究 [J]. 稀有金属, 2015, 39(3): 201-206.LI Fulin, FU Rui, FENG Di, et al. Hot deformation characteristics of Ni-base wrought super alloy CDS&W FGH96 [J]. Chinese Journal of Rare Metals, 2015, 39(3): 201-206. (in Chinese)
 夏天. 微量元素Hf和Zr对FGH96合金组织和性能影响的研究 [D] 北京: 钢铁研究总院, 2013.XIA Tian. Effect of Micro-Elements Hf and Zr on Microstructure and Mechanical Properties of FGH96 Super Alloy [D]. Beijing: China Iron & Steel Research Institute Group, 2013. (in Chinese)