An Analytical Model for Grinding Force Prediction in Ultra-Precision Machining of WC with PCD Micro Grinding Tool
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An Analytical Model for Grinding Force Prediction in Ultra‑Precision Machining of WC with PCD Micro Grinding Tool Sangjin Maeng1 · Pyeong An Lee2 · Bo Hyun Kim2 · Sangkee Min1 Received: 1 August 2019 / Revised: 24 January 2020 / Accepted: 28 January 2020 © Korean Society for Precision Engineering 2020
Abstract Micro grinding with a poly crystalline diamond (PCD) tool is one of the promising approaches for fabricating a micro mold on difficult-to-cut materials. As the process can also achieve good surface integrity without additional finishing processes, it could shorten total processing time and reduce total energy and resource impact. Modeling of micro grinding is necessary to understand the key design factors of the PCD tool which influence the grinding force inducing geometric errors in micromachining. This research proposes a model to describe the micro grinding of the difficult-to-cut material and predict the grinding force. The model for calculating the grinding force has been established considering contact area, grit size and distribution, tool shape, cutting depth, and cutting speed. Micromachining experiments with a PCD micro grinding tool fabricated by wire electro discharge machining have been conducted in tungsten carbide and provided the validation of the proposed model. Keywords Micro-grinding · Wire electro discharge machining (WEDM) · Poly crystalline diamond tool · Difficult-to-cut material List of Symbols Ac Cutting area (m2) Ap Plowing area (m2) As Contact area of the tool (m2) dg Grit size (m) dt Tool diameter (m) dg,max, dg,min Maximum or minimum grit size (m) dg,mean Mean grit size (m) Et, Ew Elastic modulus of the tool and workpiece (N/m2) F, Fn, Ft Grinding force, normal grinding force, and tangential grinding force (N) Fn,r, Fn,p, Fn,c Normal force in rubbing, plowing, and cutting (N) This paper was presented at PRESM2019. * Sangkee Min [email protected] 1
Department of Mechanical Engineering, University of Wisconsin – Madison, 1513 University Ave., Madison, WI 53706, USA
School of Mechanical Engineering, Soongsil University, 369 Sangdo‑Ro, Dongjak‑Gu, Seoul 06978, South Korea
2
Ft,r, Ft,p, Ft,c Tangential force in rubbing, plowing, and cutting (N) hc, hp Critical cutting depth and critical plowing depth (m) hit Uncut chip thickness of i grit at t moment (m) H, Hs, Hv Hardness, scratch hardness, and Vickers hardness, of the workpiece (N/m2) kd,t, kl,t Stiffness of the tool in lateral and depth direction (N/µm) kd,w, kl,w Stiffness of the workpiece in lateral and depth direction (N/µm) kx,m, ky,m, kz,m Stiffness of the machine tool in x-, y-, and z-axis direction (N/µm) kx,total, ky,total, kz,total Stiffness of the total system in x-, y-, and z-axis direction (N/µm) L Tool length (m) N The number of grits (–) P Static load (N) ri Distance of i grit from center of the tool (m) S Spindle speed (RPM) t Time (s)
Vol.:(0123456789) 13
International Journal of Precision Engineering and Manufa
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