Papers by Keyword: Glass BK7

Abstract: Both rotary ultrasonic machining (RUM) and conventional grinding (CG) experiments were performed on the glass BK7 specimen to investigate the effects of high frequency vibration on the surface quality. The surface morphologies produced in the two machining processes were assessed and the associated material removal mechanisms were explored. Also, the influence of the spindle speed on the surface roughness was discussed. It was found that the mechanisms of the material removal involved in the RUM process were material pulverization and brittle fracture, while ductile flow and brittle fracture prevailed on the material removal in CG process. The increased spindle speed would reduce the lateral cutting depth of each abrasive, and promote the shielding effects of the lateral cracks generated by the previous abrasive, leading to the reduction of the surface roughness in both RUM and CG processes.

Abstract: Experiments were carried out to study the effect of ultrasonic vibration on the surface roughness and subsurface damage (SSD) in rotary ultrasonic machining (RUM) of glass BK7. As a comparison, some conventional grinding (CG) experiments were also performed under the same process parameters with there of the RUM ones. The surface roughness of the RUM/CG samples was measured with a surface profilometer. The SSD of these specimens was assessed and characterized by a measuring microscope with the help of the taper polishing method. Also, the influence of process parameters (cutting depth, feed speed, and spindle speed) on the surface/subsurface quality was discussed. As a result, both the surface roughness and the SSD depth of the RUM/CG specimens were reduced with the increased spindle speed, while increased with the increasing of feed speed and cutting depth of the diamond tool. Compared with the CG process, the introduction of ultrasonic vibration resulted in the higher surface roughness and SSD depth, due to the fact that the max cutting depth of the abrasive in the RUM process increased by an amplitude compared with that in the CG process.

Abstract: The development of the ability to machine glass materials to optical tolerances is highly desirable. The machinability of glass is poor in diamond cutting due to the high hardness and the high brittleness of glass. In order to investigate the effects of cutting fluids on the machinability of glass, this paper selected boric acid solution and sodium carbonate solution as cutting fluids, and then scratching tests were carried out. The resulting scratches with and without cutting fluids was assessed based on the observations of the micro-morphology of the scratched grooves utilizing confocal microscope. Experimental results indicated that compared with the process without cutting fluids action, the machinability of glass BK7 can be improved by using boric acid solution or sodium carbonate solution as the cutting fluids.