我厂大型汽轮机生产中需要20t双吊钩(图1)。由于某种原因决定采用本厂设备用自由锻——模锻工艺自行生产。吊钩头部模具设计时要使杆部在模膛中的长度超过两侧钩顶部的高度(图5)。这样,在下一步自由锻拔长杆部时,锤头不致于碰伤模锻好的两侧钩顶。此外,在杆部的过渡部分,做出锥度(喇叭口形状),以免自由锻拔杆时形成折叠。在多火次分段锻压过程中经常存在一个温度过渡区。由于该区段比较小,甚至有的火次只加热而不锻压变形,故晶粒可能粗大,进而影响机械性能,严重时 I plant large steam turbine production needs 20t double hook (Figure 1). For some reason decided to use our equipment with free forging - forging process of their own production. The hook head mold is designed so that the length of the stem in the mold cavity exceeds the height of the top of both hooks (Figure 5). In this way, in the next step free forging rod section, the hammer will not bump into the good sides of the hook forging. In addition, a taper (bell mouth shape) is made at the transitional portion of the shaft so as not to cause the shaft to fold when freely swiveling the shaft. In the multi-fire sub-forging process often there is a temperature transition zone. As the section is relatively small, and even some heat only forging without heating deformation, so the grain may be coarse, and thus affect the mechanical properties, serious