Research on the machining mechanism of AISI 304 ultrasonic vibration assisted grinding

Abstract

Compared with conventional grinding (CG), ultrasonic vibration assisted grinding (UVAG) has more prospects and competitiveness in processing AISI 304. Due to the change of strength of materials, when the vibration is superimposed on the workpiece, the mechanism of ultrasonic assisted machining is different from that of tool ultrasonic assisted machining. Therefore, this article proposes a workpiece vibration grinding device suitable for UVAG to study the corresponding grinding mechanism. The vibration characteristics of workpiece ultrasonic generator were discussed based on finite element simulation and the vibration situation of the device was tested with instruments to verify the accuracy of the simulation. Meanwhile, the machining mechanism of workpiece ultrasonic vibration was studied through grinding comparative experiments. The experiment showed that the displacement curve of the output end of the ultrasonic vibration of AISI 304 with time could be approximated to a sine wave and there was no other clutter. As the amplitude percentage of the ultrasonic generator increased, the output amplitude of the transducer showed an increasing trend. The ultrasonic amplitude and the amplitude percentage of ultrasonic generator approximately follow a linear relationship. The grinding force decreased with the increase of spindle speed and amplitude, and increased with the increase of feed rate and grinding depth. Compared with conventional grinding force, the grinding force of tangential ultrasonic vibration assisted grinding (TUVAG) decreased by about 29 %, while the grinding force of radial ultrasonic vibration assisted grinding (RUVAG) decreased by about 28 %. Under the action of ultrasound, the workpiece obtained better surface morphology. Under processing conditions of vw = 25 mm/min, ap = 0.01 mm, n = 2000r/min, A = 8 μm, f = 20000 Hz, the minimum surface roughness Ra of TUVAG is 0.51, followed by RUVAG with Ra = 1.02, while the surface roughness Ra of CG is the worst at 1.56 due to grinding burns.