• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.895-898
• /
• 2001

This paper presents an optimization cutting speed(OCS) program developed to improve the machining precision and tool life in high speed machining using ball end milling. This program optimized the cutting speed that is changing at any time in free surface machining of an automobile part like a connecting load die. The technique of optimization cutting speed makes the CAD/CAM-generated NC code go through a reverse post process, conducts cutting simulation, and obtain the effective tool diameter of the ball end milling. Then it changes the spindle revolution to within the range of critical cutting speed fit for the material of the workpieces depending upon the effective tool diameter. In this study, the machining precision and tool life were compared for the two connecting load dies processed using the general cutting method and the proposed optimization cutting speed technique, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.16-21
• /
• 2002

The high speed machining center(HMC) has been widely applied to manufacture a die and trial product in many machine industry. Because the evaluation fer the HMC is not sufficiently performed and the efficient cutting conditions aren't selected, a great loss has been caused in the cost aspect. In this study, the need of preliminary running time and unstable spindle speed is presented from the analysis of acceleration in idling. The Machinability fur the TiAlN coated flat end mill and STD11( $H_{R}$C60) is evaluated from the trends of tool wear and cutting force according to cutting conditions and slenderness ratio and a low response of tool dynamometer in high speed is proved. The resonance spindle speed is identified through the tool wear and natural frequency test.t.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.10a
• /
• pp.292-296
• /
• 2002

In the present investigation, the improvement of processing efficiency in the high speed machining of GC250 is explored. This study is to evaluate the tool performance in difficult-to-material using the new developed tool. Tool performance evaluation are conducted by tool wear, surface roughness, chattering in machined surface. The tool wear of A type was smaller than B type. In type B tool the chatter mark was observed in machined surface. The good surface roughness was obtained in type A tool. Consequently, the tool performance of A type is better than B type.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1418-1423
• /
• 2004

High speed machining experiment on the heat-treated mold steel(STAVAX and CALMAX of hardness HRc 53) is carried using TiAlN coated ball endmill. Tool life and wear characteristics under the various machining parameters and cooling methods are investigated. Effect of cooling method on life and wear of the tool was compared. For most cases, tool life was not determined by the amount of wear but by th chipping on the cutting edge. It is found that tool manufacturer's cutting parameters generally agrees with the results of this experiment.

• Journal of the Korean Society for Railway
• /
• v.5 no.3
• /
• pp.33-42
• /
• 2002

김천시 및 경부고속도로를 통과하는 8-2공구는 고속철도구간 중 최고 난공사 구간중의 하나로서 (주)대우건설컨소시엄에 의해서 수행되었는데 건설초기 원가 절감과 공기완수라는 목표를 두고 전면적인 설계검토를 착수하였다. 교량구간이 전체 연장중 절반이 넘는 9.6km이므로 교량에서 대안 설계가 중점적으로 검토되었고 이에 따라 PSM(Precast Span Method)공법이 적용되었다. (토목학회지1999. 6.) PSM공법은 25m 경간이므로 도로, 철도등을 통과하는 구간에는 한계가 있어 50m 경간의 강합성교량을 적용하였다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.261-261
• /
• 2004

본 논문에서는 고속가공 시 필랫(코너-R) 엔드밀의 곡면가공 적용가능 여부를 연구하기 위하여 비교적 곡률이 완만한 곡면을 채택하여 가공실험을 수행하고 고 결과를 분석하였다. 가공재료는 금형의 재료로 많이 사용되는 SKD11 강을 선택하였다. 볼엔드밀과 필렛엔드밀의 비교를 위하여 2 종류의 공구에 동일한 가공조건으로 가공실험 하였다. 가공 중 측정된 절삭력과 가공면의 표면조도를 분석하여 일반적으로 황삭에서 주로 사용되던 필렛엔드밀을 곡률이 완만한 곡면의 정삭에 적용하였을 경우의 절삭특성과 볼엔드밀의 가공특성을 비교하였다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.888-891
• /
• 2000

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is drill wear status monitoring. With the monitoring, we may decide on optimal timing for tool change. The necessity of the detection of tool wear, fracture and the abnormal tool state has been emphasized in the machining process. Accordingly, this paper deals with the cutting characteristics of the hot-rolled high strength steels using common HSS drill. The performance variables include drill wear data obtained from drilling experiments conducted on the workpiece. The results are obtained from monitoring of the cutting force and Acoustic Emission (AE) signals, and from the detection of the abnormal tool state with the computer vision system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.927-931
• /
• 1997

In process of the finish face milling of the hardended STD11 steel(H /sab r/ c50,55) by CBN tool, the optimum tool shape is suggested,which can minimize the tool fracture and by chipping by impact. The obtained results are as follows. (1) The optimal chamfer angel was about 25 .deg. , and the suitable chamfer width was 0.2mm. (2) The nose radius of tool was most excellent at 1.2mm in the viewpoint of tool wear and surface roughness. (3) Wear speed was effected by sintering method of CBN tool B.U.E

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.878-881
• /
• 2000

Recently high speed machining is being studied actively to reduce machining time and to improve machining precision. To perform efficient high speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force, tool wear and surface roughness. In this study. the cutting force and tool wear and surface roughness are investigated in case of various cutting conditions for hardened die steel.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.5 s.98
• /
• pp.11-18
• /
• 1999

Recently high speed machining is being studied actively to reduce machining time and to improve machining precision. To perform efficient high speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force. To measure cutting forces in high speed machining, dynamometer which has high natural frequency was newly designed using 3-axes piezo force sensor. For newly designed dynamometer, calibration is conducted with sensitivity of force sensor modulated and proper preload and interference force are investigated experimently. Also, cutting force signals of newly designed dynamometer are compared with those of conventional one in high speed cutting experiment and its superiority is confirmed. Then using newly designed dynamometer, high speed machinability is evaluated about cutting force and tool wear in various cutting conditions.