【简答题】如图所示,对于头部大杆部细小的自由锻杆件,为什么选大于杆部直径的坯料经过:拔长杆部,后鐓粗头部或者先鐓粗头部,再拔长杆部二次成形方案。而不是直接选用锻件杆部直径大小的圆棒料作为坯料,经局部鐓粗头部一次成形锻件,这样的锻造方案工序更少,生产率更高。为什么?
【单选题】如图所示锻件,用自由锻锻造,坯料的直径为φ140mm,长度为220mm,其基本工序是( )。
【单选题】________a reply from my American friend Bill, I decided to send another email to him.
【简答题】Dylan was forced to re-record the song, 1 with altered lyrics, in October 1975 after concerns were raised by Columbia's lawyers that references to Alfred Bello and Arthur Dexter Bradley (the two star ...
【单选题】8 婺源所产( )同修水一带所产红茶,被誉为“纯品”。