Research On Ultrasonic Vibration Assisted Ultra-precision Grinding Of Engine Nozzle Inner Surface

Nozzle is one of the key components of EFI engine.Its performance will seriously affect the performance of the engine.The nozzle is made of hard and brittle alloys of tungsten and molybdenum,which is difficult to be machined.Grinding is used to precisely machine the inner circle of nozzle.However,there are a series of problems in traditional grinding.For example,high-speed grinding spindle need to be used to improve the surface quality,while the cost is high.The contact arc between the grinding wheel and the workpiece during grinding process is long,which could block the wheel.Moreover,it is difficult to obtain high surface quality due to the high grinding force during traditional grinding.In order to solve these problems that exist in the grinding of nozzle inner surface,ultrasonic vibration assisted precision grinding is proposed in this paper.(1)The principle of ultrasonic vibration assisted grinding was analyzed and research on the experiment device of ultrasonic vibration assisted grinding was carried out.Based on the theory study of the ultrasonic vibration assisted grinding,the rationality of ultrasonic vibration assisted grinding was confirmed.An experimental device was developed for ultrasonic vibration assisted grinding.The amplitude of ultrasonic wave was measured on-line,and the rationality of the device prove was further proved.(2)The theory of ultrasonic vibration assisted grinding particle trajectory is studied,and the grinding trajectory of single abrasive was simulated by using MATLAB software.Moreover,grinding tracks with multi-abrasive were simulated,and the effect of ultrasonic vibration grinding speed on grinding simulation results was investigated.(3)The ultrasonic vibration assisted grinding experiment was carried out.The grinding wheel was trimmed before grinding the workpiece,and the surface of the grinding wheel was analyzed before and after ultrasonic vibration aided grinding.After introducing ultrasonic vibration assisted grinding,the influence of grinding wheel speed and grinding wheel feed amount on grinding force and grinding surface was studied.The effect of ultrasonic vibration grinding process on the grinding force and the surface topography of grinding wheel was analyzed.Results show that the introduction of ultrasonic can reduce the cutting force,improve the surface quality of the workpiece and enhance the grinding performance.(4)The effect of rotating speeds of the grinding wheel and workpiece on grinding performance before and after ultrasonic vibration assisted grinding was investigated.By analyzing the workpiece surface roughness and the surface topography of grinding wheel,the rotational speeds of grinding wheel and workpiecewere optimized.The grinding performance of nozzles that made of different materials was studied before and after ultrasonic vibration assisted grinding.