Simulation and experimental analysis of composite chamfering of superhard cutting tools based on edge grinding technology

Abstract

Objectives: Circular edge chamfering PCD turning tools often feature a chamfered surface at the cutting edge to enhance tool durability. However, the arc at the tool tip causes a large amount of chip accumulation in front of the tool, making chip discharge difficult. This leads to increased cutting temperatures, accelerated tool wear, and reduced surface brightness of the workpiece. To improve the brightness of circular edge chamfering PCD turning tools when processing non-ferrous metals and enhance the tool's durability, a composite chamfering structure is created by performing secondary chamfering on the basis of the circular edge chamfering tool. Methods: Using CATIA software and based on the actual grinding process of the PCD chamfering tool by the COBORN RG9 grinder, the grinding wheel is positioned at different points along the tool's moving path using the trajectory discrete envelope method. The unmachined tool is enveloped, and the overlap between the grinding wheel and the tool is removed, resulting in a three-dimensional approximate model of the composite chamfering tool. By extracting point coordinates, performing curve fitting, surface fitting, surface joining, and other methods, a three-dimensional model of the composite chamfering tool with a cylindrical back surface is established. Deform V11.0 software is then used to simulate the 3D cutting of the PCD composite chamfering tool, calculating the root-mean-square value of the cutting force and the mean cutting temperature under different cutting depths and second-order chamfering widths, as well as under different cutting depths and second-order chamfering angles. The analysis focuses on selecting the second-order chamfering width for different cutting depths when the first-order chamfering width is fixed, and choosing the second-order chamfering angle for different cutting depths when the second-order chamfering width is fixed. Based on this analysis, the effects of different inclination angles on the machining performance of the composite chamfering tool—such as chip flow changes, tool temperature variations, and tool wear—are analyzed. Finally, cutting experiments comparing the PCD composite chamfering tool and the PCD first-order chamfering tool are conducted to analyze changes in cutting temperature under different cutting depths, surface roughness of the workpiece over different processing times, and the final wear states of the two tools. Results: The simulation analysis results show that: (1) When the first-order chamfering width is constant and the cutting depth is smaller than the first-order chamfering width, the second-order chamfering width should be greater than the cutting depth. (2) If the cutting depth is large (even close to the first-order chamfering width), the second-order chamfering width should be smaller than the cutting depth. (3) When the cutting depth is small and does not exceed the second-order chamfering area, a larger second-order chamfering angle should be selected. (4) When the cutting depth is large, a smaller second-order chamfering angle should be selected. When cutting at an oblique angle, as the inclination angle of the tool gradually increases, interference with chip removal generally increases. The wear and tool temperature of the composite chamfered turning tool generally increase, but when the inclination angle is 10°, wear and temperature of the tool are lower, and chip removal interference is minimized. (5) When cutting at an oblique angle, as the inclination angle of the tool gradually increases, chip removal interference generally shows an increasing trend. However, at a 10° inclination angle, tool wear and temperature are lower, and chip removal interference is reduced. Specific experimental results of PCD tools show that, at the same cutting depth, the cutting temperature of the PCD composite chamfering tool is lower than that of the PCD first-order chamfering tool. Furthermore, when the cutting depth is 0.14 mm and the workpiece is turned for 30 minutes, as processing time increases, the surface roughness of the workpiece processed by the PCD composite chamfering tool remians lower than that of the PCD first-order chamfering tool. Conclusions: The composite chamfering of the PCD tool improves the brightness of the workpiece when the cutting depth is greater. The final wear state of the tool indicates that the PCD composite chamfering tool has a better smoothing effect during cutting than the PCD first-order chamfering tool, resulting in higher workpiece brightness and better wear resistance.

Keywords

• pcd turning tool
• cutting depth
• surface roughnesse
• tool wear