Original control principle of hydraulic and electric system have been changed in de-sign of equipment to avoid defects such as folding, burning etc produced in upsetting of large air valve preform.

• 为防止大气门毛坯在热镦粗过程中产生的折叠、烧等缺陷,在设计设备时改变了原有的液压控制和电气控制原理。