碾环是指通过专用设备碾环机生产不同直径的环形零件，主要用来生产汽车轮毂、火车车轮等轮形零件。特种锻造包括辊锻、楔横轧、径向锻造、液态模锻等锻造方式，这些方式都比较适用于生产特殊形状的零件。
Roller ring refers to the production of circular parts with different diameters through the roller ring machine of special equipment, which is mainly used to produce wheel hub, train wheel and other wheel shaped parts. Special forgings include roll forging, cross wedge rolling, radial forging, liquid forging and so on. These methods are suitable for producing parts with special shape.
随着电动机的发明，十九世纪末出现了以电为动力的机械压力机和空气锤，并获得迅速发展。第二次***以来，七十五万千牛的模锻水压机、一千五百千焦的对六万千牛的板料冲压压力机、十六万千牛的热模锻压力机等重型锻压机械，和一些自动冷镦机相继问世，形成了门类齐全的锻造机械体系。Everytechnicianisnotallowedtobecarelessandsticktotheir。
With the invention of motor, the mechanical press and air hammer powered by electricity appeared at the end of nineteenth Century, and developed rapidly. Since the Second World War, the forging water press, one thousand and five hundred thousand char, the punching press of Liu Wanqian cattle, the hot forging press of sixteen thousand thousand cattle, and some automatic cold heading machines h***e come out in succession, forming a complete system of forging machinery.
二十世纪60年代以后，锻造机械改变了从19世纪开始的，向重型和大型方向发展的趋势，转而向高速、***、自动、精密、专用、多品种生产等方向发展。
After 60s twentieth Century, forging machinery changed the trend from nineteenth Century to he***y and large direction, and turned to high speed, high efficiency, automatic, precision, special, multi variety production.