A high-frequency electromagnetic stamping system for high-throughput stamping of microdimples

• Published in: Journal of materials processing technology Vol. 303; p. 117527
• Main Authors: Chen, Shun-Tong, Lin, Po-An, Chiang, Chao-Jung
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2022; Elsevier BV
• Subjects: Acceleration; Compressive properties; Dimpling; Electromagnetic drive; Electromagnets; Fractures; Grain boundaries; Grain refinement; Grinding; High speed; High-throughput stamping process; Indentation; Jerk; Kinetic energy; Magnetic effects; Microdimple; On-process grinding; Stamping; Tungsten carbide; Electromagnetic drive; High-throughput stamping process; Microdimple; On-process grinding; Jerk
• ISSN: 0924-0136; 1873-4774
• DOI: 10.1016/j.jmatprotec.2022.117527

A high-throughput stamping process technology is proposed for high-speed manufacturing of regular, accurate microdimple structures in large quantity. Due to the alternating nature of AC power and magnetic effect of current, the designed electromagnet is capable of creating sine vibrations at 120 Hz. Acceleration increases instantaneously when a tungsten carbide stamping head is subject to the electromagnet’s sine vibrations, resulting in a jerk motion increasing kinetic energy of the stamping head. Desired shapes and depths are realized as the stamped material is subject to high-speed impact from the stamping head. To provide timely grinding with spherical and aspherical stamping heads, an on-process grinding mechanism is designed on the CNC high-frequency stamping system, where on-process calibration is not required for the stamping head and attached residues are removed instantly. It took only 3.4 s to finish an array of 400 highly regular aspherical microdimples with no burring around the dimples; in addition, the form of the arc length is 96% consistent with the design. The arc length of the stamping head overlaps nearly 99% the formed arc length. Metallographic testing shows that the proposed stamping jerking technique produces grain refinement and grain boundary indentation on the surface of stamped microdimples that prevents dislocation and expansion of micro-fractures. Moreover, compressive stress makes the lattice structure of stamped material more solid. The study proves that this high-frequency electromagnetic stamping technology combines high speed, density and consistency with an outstanding transcription-rate. •Jerk motion is successfully employed in this high-frequency stamping process technology.•The designed E-I transformer core creates reciprocal motion of the stamping shaft at 120 Hz.•The on-process grinding design facilitates stamping head grinding and in-time removal of any residue.•The overlapping between the arc length of stamping head and the formed arc length is as high as 99%.•An array of 400 regular aspherical microdimples was created in just 3.4 s