Study On Fabrication And Application Of Ball Cutter Patterned With Micro Cutting-edge Array

Machining high-precision microstructure on curved surfaces of mechanical part and prosthesis can change their surface properties, resulting in higher performances. The current process required surface finishing, micro-structuring, and micro-deburring, which meant three sets of machine and tool and it’s tough to apply on large-scale freeform surface. Therefore, in this issue, a novel macro ball cutter patterned with micro cutting-edge array is presented. With properly 5-axis simultaneous control, this tool can mill microstructure arrays on freeform surface within one machine.Firstly, a diamond wheel V-tip is employed in the micro-grinding process, patterning micro cutting-edge array on the arc-shape cutting-edge of the ball cutter. Moreover, controlling the edge’s shape and position, as well as the changes of rake and clearance angles are studied. It is shown that the grinded micro cutting-edge arrays are smooth and tidy without burr. The average height error, average angle error and the circular radius are 4.3μm, 2.6° and 2μm-8μm of the designed 6 units, 225μm height 75° micro cutting-edge.Then, the 5-axial motion and posture controlling mode is built for the cutter and the complementary microstructure, whose 3D shape and direction are controllable, can be replicated on workpiece surface by micro machining. The milling experiment shows that the microstructure roughness and form error decrease with increasing cutting speed and decreasing feed rate. The designed 4 units 225μm height 75° micro microgroove array is machined, whose average form error and average angle error are 6.6μm and 1.7°. Besides, the cross zero cutting process is preposed for micro-pyramid deburring, which can reduce the burr height from 35μm to 5μm.Finally, utilizing CT tomogram to reconstruct and extract the patient’s 3D data of femur lumen and then design the fitted personalized artificial hip prosthesis with biocompatible microgoove arrays. By adding constraints to 5-axis mode and cutter spheroidization, the 4 units, 172μm height, 60°microgoove arrays are machine on the hip prosthesis surface, using 4-axis machining center and torus cutter patterned with micro cutting-edge array. The average surface roughness, average form error and average angle error of the microgroove arrays are Ra 2.27μm, 16.0μm and 9.9°.