INVESTIGATION OF CIRCUMFERENTIALLY-GROOVED GRINDING WHEELS FOR CREEP-FEED GRINDING

Abstract

This work investigates experimentally the use of a circumferentially-grooved grinding wheel on the creep-feed grinding process. The work was divided into three main objectives which are: investigating the performance of a grooved wheels in comparison to a regular non-grooved wheel, developing a practical method for wheel grooving, and exploring reasons why the grooved grinding wheel performed better. A single-point diamond dressing tool was used to cut shallow circumferential groove on an aluminum-oxide grinding wheel. The results showed that, for the creep-feed grinding conditions used in this research, a grooved wheel can reduce the consumed power by up to 61%, enable up to 37% more material to be removed while still maintaining workpiece surface roughness values below 0.3µm (“fine quality” surface finish), and enable up to 120% more material to be removed while still maintaining workpiece surface roughness values below 1.6µm (“average quality” surface finish). A wear study was also carried out to compare the performance of both the grooved and non-grooved grinding wheels. For the conditions used in this study, the results showed that a grooved wheel not only exhibits less wear than a non-grooved wheel but also can remove approximately twice as much workpiece material before failure occurs. A corresponding new grinding wheel grooving system was developed that is able to both groove as well as re-groove a grinding wheel using a single-point diamond tool. The re-grooving capability of the new system is achieved by synchronizing the grinding wheel angular position with the dressing tool translational position. This position synchronization enables the diamond dressing tip to repeatedly engage the grinding wheel at the same angular position around the wheel and then proceed to trace the existing groove pattern along the wheel surface to, for example, refresh a worn groove geometry. Furthermore, the proposed system can be mounted on either a conventional or a CNC grinding machines and can groove and re-groove the grinding wheel without the need to remove it from the grinding wheel spindle. The novel wheel grooving system was experimentally validated by creating helically shaped circumferential grooves on the grinding wheel surface. The developed grooving system is able to inscribe various groove patterns into the grinding wheel as well as dress the wheel. It was found that the grooved wheel performs better than regular non-grooved wheel because of an increase in the size effect as well as because more grinding fluid can be delivered into the contact zone. The grooved grinding wheel chips were approximately six to eight times wider than the chips removed by the regular wheel. Also, the grooved grinding wheel was, in comparison to the regular non-grooved wheel, able to deliver more than twice the volume of coolant fluid into the contact zone which lead to better lubrication and cooling.