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심기중,유종선,서남섭 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2003 工學硏究 Vol.34 No.-
This paper presents a theoretical analysis to estimate the undeformed chip thickness required for cutting force simulation model development in ball-end milling. In machining, cutting force is estimated by multiplying cutting cross-section area to specific cutting forces. Specific cutting force, that is cutting parameter, is one of the important factors for cutting force prediction model and has different values according to workpiece materials. Cutting cross-section area is simply estimated in 2 dimensional cutting, but not simply estimated in 3 dimensional cutting due to complex cutting mechanics. In finishing cutting of free form surface using ball-end milling, cutting is almost performed in the ball part of the cutter and tool geometry such as tool radius, helix angle along length from tool tip are varied. As a result, cutting speed, effective helix angle and rake angle of the ball end mill are different according to length from tool tip. Study on undeformed chip thickness can be based other research, for example, cutting force prediction, tool deflection and dimensional error characteristics simulation. For undeformed chip thickness estimation, tool and chip geometry are analyzed and then the definition of chip thickness and estimation method are described. The results of analysis are compared with geometrical simulation and other method.
심기중,유종선,유기현,정진용,Sim, Ki-Joung,Yu, Jong-Sun,Yu, Ki-Hyun,Cheong, Chin-Yong 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.1
Machining error is defined the normal distance between designed surface and actual tool path with tool deflection. This is inevitably caused by the tool deflection, tool wear, thermal effect and machine tool errors and so on. Among these factors, tool deflection is usually known as the most significant factor of machining error. Tool deflection problem is analyzed using Instantaneous horizontal cutting forces. The high quality and precision of machining products are required in finishing. In order to achieve these purposes, it is necessary work that decrease the machining error. This paper presents a study on the machining error caused by the tool deflection in ball end milling of 2 dimensional surface. Tool deflection model and simple machining error prediction model are described. This model is checked the validity with machining experiments of 2 dimensional surface. These results may be used to decrease machining error and tool path decision.
심기중,문홍주,이영춘 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.2
This paper presents the development of the transfer case for a 3.5-ton commercial vehicle. A transfer caseis composed of many parts, including helical gear, shaft, bearing, planetary gear, and others. Helical gears arecurrently used as power transmitting gears due to their relatively smooth and silent operation, large loadcarrying capacity, and operation at higher speeds. The key parameter in transfer case development is thebending stress at the root of a tooth in the helical gear. The bending stress of the helical gear has beenstudied through theoretical calculation and finite element method (FEM) analysis. Major factors of the bendingstress calculation are determined according to American Gear Manufacturers Association (AGMA) standards,and FEM model analysis of the helical gear is conducted. FEM results are compared with theoreticalcalculations and the difference of the bending stress is described.
심기중,문홍주,전남진 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.2
This paper suggests a way to improve the strength of the driveshaft, which is a vulnerable part of the driveaxle system, for a 3.5-ton commercial vehicle. The driveshaft is composed of a universal joint with a spider andyoke, yoke shaft, etc. The driveshaft is developed by choosing design parameters for the spider and yoke suchas the diameter and distance through the structural analysis of the driveshaft’s components. Some driveshaftdesign cases have been made and analyzed with ANSYS; the strength of the driveshaft parts are validated fromthese results to propose an optimal design case. Finally, we suggest a driveshaft system that satisfies theworking conditions for a 3.5-ton commercial vehicle.
심기중(Ki-Joung Sim),문상돈(Sang-Don Mun) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.2
This paper describes a analysis on the chip thickness model required for cutting force simulation in ball-end milling. In milling, cutting forces are obtained by multiplying chip area to specific cutting forces in each cutting instance. Specific cutting forces are one of the important factors for cutting force predication and have unique value according to workpiece materials. Chip area in two dimensional cutting is simply calculated using depth of cut and feed, but not simply obtained in three dimensional cutting such as milling due to complex cutting mechanics. In ball-end milling, machining is almost performed in the ball part of the cutter and tool radius is varied along contact point of the cutter and workpiece. In result, the cutting speed and the effective helix angle are changed according to length from the tool tip. In this study, for chip thickness model analysis, tool and chip geometry are analyzed and then the definition of chip thickness and estimation method are described. The resulted of analysis are verified by compared with geometrical simulation and other research. The proposed chip thickness model is more precise.