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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.
이성철(Seong-Cheol Lee),이영춘(Young-Choon Lee),심기중(Ki-Joung Sim) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
This paper is about the development of Automatic FPC punching instrument. FPC(flexible printed circuit) is used to detect the contact position of K/B and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2㎜ and the above. Because the punching operation is done manually, the accuracy of the punching degree is varied with operator"s condition. Recently, The punching accuracy has deteriorated severely to the 2㎜ punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used for the sake of cost down instead of using high quality vision systems for the FA. Test algorithm shows good results to the designed automatic punching system.
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.