An experimental investigation of dry-electrical discharge assisted truing and dressing of metal bonded diamond wheel

摘要

Metal-bonded diamond wheels have superior qualities such as high bond strength, long wheel life, wear-resistant ability and high grinding efficiency. But it is very difficult to true and dress diamond wheel because of its highest hardness. Traditional mechanical truing does not guarantee truing accuracy of diamond wheel because of single diamond dresser wears out very quickly. To reduce wear of diamond dresser and hence guarantee a desired wheel surface, a novel truing and dressing method, namely, dry electrical discharge (dry-ECD) assisted truing and dressing, is proposed and tested to achieve good dressing quality and efficiency. Because the diamond wheel is mounted on the MK9025 optical profile grinder, dielectric liquid is forbidden. The new dry-ECD dressing/truing method basically eliminates the use of dielectric liquid. Therefore, it is free from the serious problem of electrolytic corrosion caused by electrolytic current flowing through water encountered in conventional ECD. The FE analysis of temperature distribution in dry-ECD assisted truing and dressing diamond wheel using ANSYS is performed in this study. Temperature field simulation helps to select optimized parameters under certain conditions. Energy dispersive X-ray (EDAX) analysis was used to measure the composition of diamond wheel before and after dry-ECD assisted truing and dressing. Further, hard alloy grinding experimental results proves that a little variation in material composition of diamond wheel after dry-ECD assisted truing and dressing does not influence grinding result. A series of experiments of dry-ECD assisted truing and dressing of metal bonded diamond wheel are conducted to investigate truing efficiency, truing accuracy, dresser wear, dressed wheel profiles and three-dimensional truing/dressing forces in comparison with those of the conventional single diamond methods. Experimental results show that the new dry-ECD assisted truing and dressing technique offers a number of advantages over the conventional single-tip diamond dressing and truing method. Furthermore, mechanism of the dry-ECD assisted truing and dressing is investigated through the careful analysis of the properties of chips.