Papers by Author: Chul Kim

Abstract: An internal lobe pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other other applications. In particular, this type of pump is an essential element of an automotive engine to feed lubricant oil. We perform a theoretical analysis of the internal lobe pump whose main components are rotors. Usually, the outer is characterized by a lobe with elliptical and involute shapes, while the inner rotor profile is determined as the conjugate to the other rotor. Our integrated system, which is composed of three main modules, was developed through AutoLISP using AutoCAD. It generates a new lobe profile, and automatically calculates the flow rate and flow rate irregularity according to the lobe profile generated. Results obtained from the analysis enable the designer and manufacturer of oil pumps to be more efficient.

Abstract: Ti-Al-Si-N and Ti-Al-N coatings were deposited on WC-Co substrates by a DC magnetron sputtering method. The oxidation behavior of two kinds of Ti0.75Al0.25N and Ti0.69Al0.23Si0.08N coatings were comparatively investigated by XRD patterns and GDOES depth profiles. Si addition of 8 at.% into Ti-Al-N film modified its microstructure to a fine composite comprising, Ti-Al-N crystallites and amorphous Si3N4, and to a smoother surface morphology. While the solid solution Ti0.75Al0.25N film had superior oxidation resistance up to around 700°C, the composite Ti-Al-Si-N film showed further enhanced oxidation resistance. Both Al2O3 and SiO2 layers played roles as a barrier against oxygen diffusion for the quaternary Ti-Al-Si-N film, whereas only the Al2O3 oxide layer formed at surface did a role for the Ti-Al-N film. The cutting performances of two coated carbide ball-end mills were evaluated by cutting of AISI D2 cold-worked die steel (60 HRC) under high-speed cutting condition. The tool wear and cutting temperature are discussed along with coating characteristics.