Studies on ceramics micro machining with minute-size diamond quill

近年来，机电一体化产品迅速向集成化、小型化方向发展，微细加工已成为其中一个重要的研究方向。尤其是主要部件通常由陶瓷等硬脆材料制成。由于这些材料很难用普通的物理或化学方法进行加工，因此主要使用钻石砂轮进行研磨。本研究的目的是研制一台微细金刚石砂轮的微细磨削机床，获取微细磨削的基础数据，为了在直径小于1Nim的砂轮上获得标准的磨削速度，要求主轴转速大于10万转/分。这种微细磨削中的其他问题是毛刺的断裂和弹性变形。基于上述概念，设计并生产了一台磨床。该机采用高频主轴，最大转速为120,000转/分，由气动静压气体轴承、磨削力监测测力仪和交流伺服电机驱动的X-Y工作台组成。在该机床上磨削陶瓷，得到以下结果：(1)磨削力取决于砂轮速度，在120,000转/分范围内主轴速度越快，磨削力越小。(2)磨削力仅随进给速度增加而增加，从而可以通过控制进给速度来控制磨削力。(3)磨削力随磨削长度成正比增加。随着砂轮中金刚石粒度的增大，磨削力的增加率逐渐减小。(4)在垂直于切削槽处的工件上施加振动，显著降低了磨削力。

Mechatronic products tend rapidly toward integration and smallization in recent years, so that micro machining has become one of the most important subjects. Especially, main parts are usually made of hard-brittle materials such as ceramics. Because these materials are difficult to process with general physical or chemical method, they are ground mainly using diamond wheels. The objects of this research are to develop a machine for micro grinding by using a minute-size diamond quill and to eam fundamental data of the micro grinding.In order to obtain a standard grinding speed on a quill of which diameter is below 1 nim, the spindle is required of rotational speed more than 100, 000rpm. Other problems in this micro grinding are breakage and elastic deformation of the quill. Based on the above concepts, a grinding machine was newly designed and produced. This machine was equipped with a high frequency spindle of 120, 000rpm in max., and was constructed of areo-static gasbearing, a dynamometer for monitoring the grinding force and a X-Y stage driven by an AC servo motor.Through grinding ceramics on this machine, the following results were obtained.(1)The grinding forces depend upon the wheel speed, the faster spindle speed in the range to 120, 000rpm leading to the lower grinding force.(2)The grinding forces increase simply with increasing workpiece feed speed, so that they can be controlled by operating the feed speed.(3)The grinding forces increase proportionally to grinding length, and those increasing rates decrease with increasing diamond-grit size of quill.(4)Adding vibration to the workpiece vertically to the cut groove reduces the grinding force notably.