前言我厂在一九六八年承担制造20吨中速磨煤机。其中一项要加工的关键件是模数等于16的螺旋伞齿轮。这在上海地区还未加工过,为了完成国家下达的生产任务,必须攻此项关键件,我们发扬“自力更生”的革命精神,组成三结合小组,在全厂职工的积极支持下,从我厂的现有条件出发,大搞技术革新和技术革命,改革机床,自制刀具,坚持 Foreword I plant in 1968 to undertake the manufacture of 20 tons of medium speed coal mill. One of the key elements to be machined is a helical bevel gear with modulo 16. This has not yet been processed in Shanghai. In order to fulfill the production tasks assigned by the state, we must attack this key piece. We have taken the revolutionary spirit of “self-reliance” to form a three-pronged group. With the active support of the entire factory workers, Starting from the existing conditions, engage in technological innovation and technological revolution, reform machine tools, homemade knives, adhere to