Investigations of the "speed effect" on critical thickness of chip formation and grinding force in high speed and ultra-high speed grinding of superalloy

Abstract

In order to investigate the influence law of chip formation process affected by grinding speed, the single-grain tests are carried out on the difficult to cut materials superalloy GH4169. The single-grain grinding forces are measured. The trances and chips morphologys of the single-grain grinding tests are observed and analyzed to calculate the critical thickness of chips formation. The speed effect on the grinding process scratches and grinding forces are studied systematically in the grinding wheel velocity range 20 m/s to 165 m/s. The results show that the grinding speed affects the division of grinding process and the critical thickness of chip formation, and the single-grain grinding forces first increase then decrease and increase finally with the increasing grinding velocity. Machinability changes due to the speed effect, and these changes caused by the alternative variation of the leading position between the strain rate strengthening effects and the thermal softening effects on the difficult to cut materials. Serrated chip occurs during single-grain grinding superalloy, as the grinding speed increases, the grade of serrated tooth grows and the pile up rate of the single-grain grinding grooves decrease first then increases, these phenomenon indicated that mechanism of chip formation due to the speed effect. © 2013 Journal of Mechanical Engineering.