细粒度金刚石砂轮椭圆超声振动修整试验研究

Experimental research on dressing fine grain diamond grinding wheel assisted by elliptic ultrasonic vibration

针对硬脆材料精密加工中细粒度金属结合剂金刚石砂轮修整精度低、修整速度慢、成本高的难题,开发了基于局部共振设计方法的新型单驱动椭圆振动超声修整装置,设计了专用试验砂轮。修整试验结果表明:与普通机械修整方式比较,椭圆超声振动修整后的砂轮表面磨粒分布均匀、静态磨粒数增加;磨粒表面平滑完整,多个棱边有完整锋利的磨刃;同时,结合剂三角洲面积减小,磨粒突出高度增大,延性修整痕迹明显。随着修整切深增加,单位面积上砂轮突出磨粒数减少,砂轮的承载率下降,磨粒锋利性降低;随着修整导程增加,各截层的磨粒数逐步减少,但是承载率增加,磨粒变得锋利;砂轮转速增加,椭圆超声振动修整的效果减弱,砂轮磨粒锋利性降低,而超声功率增大有利于改善修整效果。选择合理参数,采用椭圆振动超声复合修整技术,可以实现细粒度金刚石砂轮的低成本快速修整。

A new dressing setup with elliptic ultrasonic assistance for ultra-precision grinding of hard-brittle materials was developed based on the theory of local resonance, to solve problems such as high cost, low dressing speed and low accuracy. The acoustic system was driven by single longitudinal vibration, and the special dressing wheel was designed for SEM observation. Experimental results showed that the distribution of grains on the elliptical vibration dressed diamond grinding wheel is more even than that of mechanical dressed one, and counts of static effective grains increase. The grain surface dressed by elliptic vibration is smooth and one grain has several sharp cutting points; the area of bond tail decreases and the protrusion height of the grains increases. The ductile dressed trace is obvious to be observed from SEM pictures of elliptic vibration dressed wheel surface. The counts of effective grains on the unit area of elliptic vibration dressed wheel surface decrease against the dressing depth, and the bearing capacity of grinding wheel and the sharpness of the grains decrease as well; the counts of effective grains in every section layers drop gradually along with the dressing lead, but the hearing capacity of grinding wheel increase and the grains become sharp. The effect of elliptic vibration weakens when the dressing speed increases. The technology of elliptic vibration dressing is able to fulfill the low cost and rapid dressing of fine grain diamond grinding wheel with reasonable dressing parameters.