Experimental Study on Flexible Fiber Assisted Shear Thickening Polishing for Cutting Edge Preparation of Core Drill

Abstract

To improve the cutting performance of the core drill, the flexible fiber assisted shear-thickening polishing (FF-STP) for cutting edge preparation was proposed to eliminate the microscopic defect and obtain proper radius of the cutting edge of the core drill. The flexible fiber was introduced into the shear-thickening polishing process to break the thickened agglomerates and improve the efficiency of cutting edge preparation. The influence of the polishing speed, abrasive concentration and the flexible fiber contact length with the core drill on the cutting edge radius r and surface morphology of the core drill edge was analyzed, and the drilling experiments were carried out after preparation, the cutting heat and drilled holes’ roughness were employed as evaluation indexes to evaluate the performance of the core drill. The results show that the cutting edge radius increases with the increase of polishing speed, abrasive concentration and contact length. However, too high a polishing speed and contact length reduce the abrasive particles involved in the polishing process, and then lead to a decline in preparation efficiency. Under the selected processing conditions, the cutting edge radius increases from the initial 5 μm to 14 μm and 27 μm with 4 min of treatment and 6 min of treatment preparation, respectively. The sharp cutting edge becomes rounded, the burrs and chipping on the cutting edge are eliminated, and the average roughness (Ra) of the flank face decreases from 110.4 ± 10 nm to 8.0 ± 3 nm. Nine holes were drilled consecutively by core drills after cutting edge preparation, and the cutting temperature and drilled holes’ roughness were recorded. The maximum cutting temperature (122.4 °C) in the process with the prepared core drill (radius r = 14 μm) is about 20 °C lower than that with untreated one, and the roughness of the drilled hole (Ra 510.5 nm) about 189.9 nm lower. The results indicates that FF-STP is a promising method for high consistency preparation of the core drill cutting edge.

Simulation and Experimental Study on the Effect of Edge Radius on the Cutting Condition of Carbide Inserts

“…A schematic and experimental setup for the shear-thickening processing system are shown in Figure 8. Based on previous research [15], an optimal processing parameter combination was adopted with a polishing speed of 70 rpm, an abrasive size of 5000 #, and an abrasive concentration of 6 wt.%. To achieve uniform polishing, the insert edge was set parallel to the bottom of the polishing tank.…”

“…Lyu et al [14] used a brush-assisted STP method to process an insert and reduced the surface roughness of the cutting edge from 118.01 nm to 8.13 nm. Shao et al [15] used a flexible fiber-assisted STP method to process the edges of threaded combs, and the edge radius of each cutting edge was achieved after 10 min of polishing (50.0 ± 5.0) µm. Chan et al [16] used an STP preparation method to control the cutting edge geometry of a tool.…”

Parameters Optimization of Active Flexible Tool‐Assisted Shear Thickening Polishing Method for Concave Surface

“…The average surface roughness R a on the cutting edge decreases from 118.01 to 8.13 nm in 10 min of polishing, significantly increasing polishing efficiency. Shao et al [ 19 ] proposed FF‐STP for‐cutting edge preparation to eliminate the microscopic defect and obtain the proper radius of the cutting edge of the core drill. With 6 min of treatment preparation, the sharp cutting edge becomes rounded, the burrs and chipping on the cutting edge are eliminated, and the average roughness ( R a ) of the flank face decreases from 110.4 +/− 10 nm to 8.0 +/− 3 nm.…”

“…Subsequently, to obtain uniform surface roughness of the complex cutting edge of the cemented carbide insert in the polishing process, flexible tools are introduced. [ 18,19 ] Although the comprehensive performance of surface quality obtained by the assistance of flexible tools method is improved, an air pressure difference in the outer region of the processing zone generated by the high rotation of polishing tool obstructs the entry of slurry and then reduces the polishing efficiency.…”