Influences of shim stiffness on the vibration response of tool-shim system and the impact fracture resistance of cutting tool in intermittent cutting.

In cutting, the mechanical impact caused by material mechanics, geometric discontinuity, and intermittent cutting process is the main factor that induces cutting tool fracture. Impact fracture and fatigue failure of cutting tools are sudden, which can be harmful to safe production and quality control. In this paper, the effect mechanism of shim stiffness on the impact fracture performance of a tool in a mechanically clamped cutting tool system is studied. Furthermore, the vibration model of the tool-shim system is established to analyze the impact loading response characteristics of the tool-shim system under different stiffness shims. Meanwhile, the effect of shim stiffness on the loading rate, peak value, high-level fluctuation, unloading rate, and elastic energy release of shim elastic reaction force is explored. Apart from that, theoretical analysis of the stress field change near the tool crack tip is carried out. Finally, intermittent turning experiments are performed, including carbide inserts with four shims of N8 aluminum alloy, TC4 titanium alloy, 08 steel, and YT14 cemented carbide. Moreover, the analysis of each stage of the vibration response is verified. According to the results, the stiffness of the shim affects both the impact fracture of the tool basal body and the coating peeling. Besides, appropriately weakening the shim stiffness can reduce the load peak value of the shim elastic reaction force on the tool, the high load fluctuation amplitude, the unloading rate, and the dynamic stress intensity factor (DSIF), which can be conductive to improving the impact damage resistance of the tool. [ABSTRACT FROM AUTHOR]