旋转超声磨削加工中影响磨具寿命的结构参数优化

Optimization of structure parameters affecting tool life in rotary ultrasonic grinding machining

为了提高陶瓷基零部件的旋转超声磨削加工精度,降低磨具磨损造成的加工误差,建立了超声振动磨具寿命与磨粒粒度、浓度、磨具内圆直径等结构参数间关系的数学模型,对影响超声振动磨具寿命的结构参数进行了优化。首先,基于响应曲面法,建立了青铜基超声振动磨具二阶寿命模型,通过Box-Behnken实验对超声振动磨具寿命模型进行了拟合。然后,通过有效性和显著性检验,验证了所建立的超声振动磨具寿命模型。最后,通过拟合影响因子与超声振动磨具寿命关系的响应曲面和等高线,分析了各因素对磨具寿命的交叉影响,并优化了磨具的结构参数。结果表明:当磨粒粒度为D98.85、浓度为77.36、磨具内圆直径为5.34mm时,去除体积为9 600mm3、致密度为85%的Si3N4陶瓷材料后,磨具磨损量只有0.006 9mm,显示优化后超声振动磨具寿命可以达到旋转超声精密磨削加工要求。

This paper focused on improving machining precision and reducing the machining errors caused by tool wearing in a Rotary Ultrasonic Grinding Machining（RUGM）. The relation model be- tween the ultrasonic vibration tool life and the grit sizes, grit concentration and the inner circle radius of a tool was established, and the parameters affecting ultrasonic vibration tool life were optimized. First, the second order model of ultrasonic vibration tool life was established for a bronze-bonded ul- trasonic vibrating tool with Response Surface Methodology （RSM）, and the model was fitted based on Box - Behnken experiments. Then the ultrasonic vibration tool life model was checked by effectiveness and significance tests. Finally, the cross-fertilization between the various influence factors and the tool life was analyzed through fitting the response surface and the contour between ultrasonic vibration tool life and factors, and the ultrasonic vibration tool parameters were optimized. The results indicate that the wear capacity of ultrasonic vibration tool is only 0. 006 9 mm, after removing 9 600 mm3 for SiaN4 ceramics materials with density of 85%, when the grit size is D98. 85, grit concentration is 77.36, and the inner circle radius of the tool is 5.34 mm. It satisfies the finish machining requirements for RUGM.