• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.3
• /
• pp.16-23
• /
• 2004

Thermally induced errors of machine tools have been recognized as one of the most important issues in precision machining. This is probably the most formidable obstacle to obtain high level of machining accuracy. To this regard, the experimental compensation methodologies such as software-based method or origin shift of machine tool axes have been suggested. In this research, to cope with thermal deformation, a model based correction was carried out with the function of an external machine coordinate shift. Models with multi-linear regression or neural network were investigated to selected a good one for thermal compensation. Consequently, multi-linear regression model combined with origin shift was verified good enough form the machining of dot matrices of plate with ball end milling.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1248-1252
• /
• 2005

Mold-manufacturing process consists of machining and finishing process that are strongly related in each other. But there are few studies about mold-manufacturing process to control those two processes simultaneously. Especially, runout distorts the machined surface from expected so it changes the finishing process and mold-manufacturing time. In this work, basic analyses and experiments were carried out to study RVAS variation according to runout in HSM. To perform those analyses, firstly surface generation analysis was done including runout in ball end milling and then the RVAS that could relate machining and finishing process was proposed. And the optimal finishing process in HSM according to RVAS was also proposed. Through experiment runout occurrence and above analyses were verified.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.219-224
• /
• 2002

There are two important variables in machining process control, which are feed and cutting speed. In this work, a two degree-of-freedom controller is designed and implemented to achieve on-line cutting force control based on the modelling of cutting process dynamics which are established through step response test. Two schemes are proposed and implemented. The first is feed control under the constant spindle speed and spindle speed control under the constant fled speed. The second is a simultaneous control of feed and spindle speed. Those are confirmed to work properly. Especially the latter shows a faster response and we'll be evaluated to pare away workpiece by simultaneous control of position and cutting farce sooner or later.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.6
• /
• pp.84-91
• /
• 2003

In metal cutting operation, it is very important that predict cutting force and work surface. Vibration is an unstable cutting phenomenon which is due to the interaction of the dynamics of the chip removal process and the structural dynamics of machine tool. When vibration on, it reduces tool life, results in poor surface roughness and low productivity of the machining process. In this study, the experiments were conducted in machining center without cutting fluid to investigate the phenomenon of vibration. In the experiments, accelerometers were set up at the tail stock and tool holder and signals were picked up. Surface roughness profiles are generated under the ideal condition and the occurrence of vibration based on the surface shaping simulation model.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.371-374
• /
• 1997

This study presents a new type of real-t~me CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter-contact (CC) path scheduling and CC path interpolation. Especially, in this study, a new interpolator module to regulate cutting forces is developed. This proposed algorithm utilizes variable-feedrate commands according to the curvature of machined surfaces. The proposed interpolator is evaluated and compared with the conventional method based on constant feedrates through computer simulation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.184-189
• /
• 2003

In metal cutting operation, it is very important that predict cutting force and work surface. Vibration is an unstable cutting phenomenon which is due to the interaction of the dynamics of the chip removal process and the structural dynamics of machine tool. when Vibration occurs, it reduces tool life, results in poor surface roughness and low productivity of the machining process. In this study, the experiments were conducted in machining center without cutting fluid to investigated phenomenon of the Vibration. In the experiments, accelerometers were set up at the tail stock and tool holder and the signals were picked up. In this paper, surface roughness profiles will be generated under the ideal condition and the occurrence of the vibration based on the surface shaping simulation model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.121-126
• /
• 2000

This research proposes a new advanced control method and demonstrates its realization in part. By incorporating shape machining and cutting force control at a time, this integrated scheme makes it possible to machine a desired shape and avoid the trouble of programming feedrate and spindle speed before machining and also reduce the shape error. The main idea proposed to achieve those goals consists in giving commanded path and desired cutting force at the same time. which makes it possible for position and force controller to distribute the corresponding velocity of individual axes and main spindle by an appropriate interpolation. That indicates we can replace the built-in interpolator of commercial machine tools by the developed algorithm.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.3
• /
• pp.71-76
• /
• 2020

Various machining methods are being studied to improve the processing quality of the spherical R shape in press die. In this paper, we confirmed that changes in machining quality were associated with changes in cutting direction, path, and cutting angle, which are commonly used in the machining of molds. We obtained a surface roughness graph with each condition change in one specimen using an instrument that measured geometry and surface roughness simultaneously. The results of the study showed that the best surface roughness in the finish cut of the spherical surface was obtained using upward pick feed machining.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.10a
• /
• pp.206-210
• /
• 2000

금형 및 자동차 산업에 널리 사용되는 앤드밀 가공에서 종종 소비자가 요구하는 가공 정밀도를 충족시켜 주지 못하는 경우가 발생한다. 이것은 열 변형, 공구 마모, 공작 기계 자체의 오차, 공구 처짐 등 다양한 원인이 존재한다. 본 연구에서는 공구 처짐으로 발생되는 가공 오차를 줄임으로써 가공 정밀도를 향상하기 위한 시스템을 개발하고자 한다. 이를 위해 3차원 볼 앤드밀의 절삭력 모델을 개발하고 시뮬레이션한다. 또한, 상용 CAD 시스템의 형상 및 가공 정보를 이용함으로써 모델링에서부터 가공 경로 생성, 그리고 경로 보정이라는 과정을 일괄적으로 수행할 수 있도록 한다. 이를 통해 사용자는 가공 전 시뮬레이션을 통해 가공 오차를 줄일 수 있는 기회를 제공 받는다. 따라서, 실제 가공에서 보다 높은 가공 정밀도를 얻을 수 있을 것이다.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.4
• /
• pp.73-80
• /
• 1993

There and two important variables in machining process control, which are feed and cutting speed. It is possible to improve the machining accuracy and the productivity by maintaining the optimal feed and cutting speed. In this work, a controller is designed to achieve on-line cutting force control based on the modeling of cutting process dynamics established through step response test. Two schemes are proposed and implemented. The first is feed control under the constant spindle speed and the second is spindle speed control under the constant feed. Finally, both are proved to work properly through simulation and experimentation.