Ultrasonic Vibration Dressing Technology On Superabrasive CBN Grinding Wheel

In recent years, the hard-brittle materials have won so wider recognition all over the world and have been applied in many fields, such as in aeronautical and space technologies, automotive electronics, precise meter and instrument. These materials generally have high processing value-added. In order to ensure its widespread status in exact science engineering field and obtain high dimension and form accuracy, a large number of ultra-hard grit grinding wheels begin to use. The CBN grinding wheels play a significant role with its outstanding performance. Grinding is the main processing means which makes these difficult materials high-quality be used. In order to ensure high precision grinding process carried out, the problem about the dressing of grinding wheels must be solved. The dressing technology of CBN grinding wheel have greatly developed at present, and the wheel life and grinding efficiency have been improved to some extent. However, different dressing methods have varying degrees of limitations, and can't be applied into wide use, therefore, it is necessary to study a low-cost, simple structure, convenient and efficient dressing method.Based on outstanding performance of vibration cutting, the diamond pen composite dressing technology added ultrasonic vibration is put forward. The technology not only promotes the advantages of the vibration but also excludes shortcomings of ordinary diamond pen dressing. Vibration dressing is simple, easy to use, high efficient and stable, obtaining an ideal surface topography and solving the problem of poor grinding ability in ordinary dressing.Based on the wave theory, combined with vibration principle, characteristics of wave propagation in variable cross-section bar are studied, besides, according to Impedance Synthesis Method, mechanical impedance of vibration device is matched each other. And based on theoretical analysis, the geometry design of various vibration components is completed. Amplitude and frequency characteristics of acoustic devices are analyzed on test.Based on the study of vibration cutting, the grinding wheel dressing mechanism of ultrasonic vibration is analyzed, besides, comparing with ordinary dressing, the dressing mode added vibration has greater advantage, by discussing the characteristics of vibration dressing. The grinding wheel surface profile shape of the vibration dressing and the grain micro state characteristic are explored. In a state of continuous dressing, the diamond pen contacts with grinding wheel surface continuously, and the entire dressing process is vibration dressing. The dressing surface of grinding wheel has relatively large chip space, grain also more sharp. Whereas, about intermittent dressing, there are some primary surface which is not dressed on the surface of the grinding wheel, and flat-topped profile shape appears at the top of morphology. And based on the measurement method of three-dimensional white light interference scanning, sampling interval of surface grain recognition is proposed, and filtering technology is also introduced. Therein, the surface three-dimensional shape parameter indexes are established.Compared with ordinary dressing, the experimental results show that the grain of resin bonded CBN grinding wheel can remain perfect after ultrasonic vibration dressing, have good grinding wheel topography, and have higher excellent grinding quality. Under traditional dressing mode, material removal mechanism of dense type grinding wheel is mainly brittle fracture of grain and bond rupture, while under the ultrasonic vibration dressing mode, the material removal mechanism is mainly ductile cutting of bond materials, abrasion and fracture of grains. Under ultrasonic vibration dressing mode, coarse-grained dense-type bonded grinding wheel can complete the dressing, while the fine-grained resin bonded grinding wheel has a small number of effective abrasive and its grain height are lower. Influencing regularities of dressing parameters on grinding wheel surface morphology are experimentally analyzed. Finally, the grinding characteristics of CBN grinding wheel are tested. The experimental results show that the CBN grinding wheel of vibration dressing mode has relatively large grinding ratio compared with ordinary dressing. Grinding wheel's grind ability has been improved. So it can be concluded that the grinding wheel's surface topography is better, with larger chip space and sharp grains after vibration dressing. In grinding process, the removed amount of the grinding wheel's radius is relatively stable, grinding temperature is lower, and thereby the grinding wheel is decreasing wearing. In the same conditions, relatively grinding ratio of high-speed steel is higher than K9 optical glass. It can be drawn from grinding test that optical glass's grinding surface quality is dissatisfied. The surface roughness is relatively lower, and texture is irregular. But, the CBN grinding wheel has a higher advantage when grinding high-speed steel. The grinding surface quality is higher and the surface texture is delicate and regular.