在有关球磨机的教科书中,载有一整套关于研磨体瀑落运动规律的说法(以后简称“原说”)。我们将在本文中指出,“原说”仅适用于敷设有平衬板的磨机,而处在瀑落状态的粗磨阶段实际上从来不用平衬板。本文以阶梯衬板作为典型例子,指出凸型衬板对研磨体的提升作用。 In the textbook about ball mills, there is a whole lot of talk about the movement law of the falling bodies of grinding bodies (hereinafter referred to as the “original”). We will point out in this article that the “original” is only applicable to mills with flat linings, and flat linings are practically never used in the roughing stages in waterfall conditions. In this paper, as a typical example of step liner, pointed out the role of convex liner on the grinding body.