• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.433-442
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• 1989

Owing to the development of CNC machine tools and automatic programing software, the milling process with ball-end mill has become the most widely used process where three-dimensional precision machining is important. In this study, the ball-end milling process has been analyzed and a cutting force model has been developed to predict the cutting force acting on the ball-end mill on given machining conditions. The development of the model is based on the analysis of geometry of a ball-end mill an the oblique cutting process. The cutting edges of ball-end mills are considered as a series of infinitesimal elements and the geometry of the cutting edge element each cutting edge element is straight. The oblique cutting process in the small cutting edge element has been analyzed as orthogonal cutting process in the plane containing the cutting velocity vector and chip-flow vector. Hence, with the orthogonal cutting data obtained from orthogonal turning test, the cutting forces can be predicted through the model. The predicted cutting forces has shown a fairly good agreement with the test results in various plane cutting conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.1067-1082
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• 1991

본 연구에서는 비교적 강성이 약한 볼 엔드밀 공구에 있어서 처짐으로 인한 그 가공 특성을 알기 위하여, 변화된 칩 두께 및 처짐 모델로부터 절삭력을 예측하며 또한 절삭력에 의한 공구의 처짐으로 인하여 공구의 플랭크 부위와 공작물간의 발생하 는 간섭 특성을 고찰하고, 이러한 특성이 절삭성과 가공 오차에 미치는 영향을 실험을 통하여 분석하여 본다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1170-1182
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• 1989

본 연구에서는 해석 기하학적인 접근 방법으로서 전단응력으로 표현되는 3차원 절삭이론을 유도하고 이것을 정면밀링의 해석에 적용하여 기본적인 파라메트 들은 실험이 비교적 용이한 선삭에서 결정하고 그들을 이용하여 밀링절삭력을 유효 하게 예측할 수 있도록 하는 방법을 제시하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.81-85
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• 1993

정면밀링은 급속 가공을 매우 효율적으로수행할 수 있기 때문에 널리 사용되고 있다. 그러나 밀링커트는 단속 절삭 공구로서 절삭날의 단속절삭작용에 의한 변동적삭력과 여러날의 동시가공에의한 절삭력의 교란 때문에 절삭성이 기계가공에 문제가 되어 왔다. 이러한 문제점들을 해결하기 위하여 기계설계자들은 절삭 력의 교란에 의하여 일어나는 진동을 줄이기 위하여 기계구조의 강성을 증가시켰으나 이것은 비용이 많이 들게 되므로 공구 형상을 개선하여 안정된 절삭을 시도하였다. 본 연구에서는 절삭력 모델을 이용하여 변위 발생의 원인인 절삭력변동을 최소로 하는 커터의 형상을 3차원으로 최적 설계하였다. 최적 설계 제작된 공 구와 재래식 공구를 사용하여 절삭력, 공구수명, 표면조도를 측정하였다. 최적 설계 제작된 공구와 재래식 공구에 의하여 측정된 결과들을 비교 검토하여개발된 공구의 절삭특성을 규명하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.424-432
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• 1989

A mathematical model is developed for determination of the dynamic cutting force from static cutting data. The dynamic cutting force is analytically expressed by the static cutting coefficient and the dynamic cutting coefficient which can be determined from the cutting mechanics. The proposed model is verified by the chatter stability charts. A good agreement was shown between the stability limits predicted by the theory and the critical width of cut determined by experiments. The static cutting coefficient dominates high speed chatter stability, while the dynamic cutting coefficient dominates low speed chatter stability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.2
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• pp.1-8
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• 2002

Cutting force is obtained as a sum of chip removing force and ploughing force. Chip removing force is estimated by multiplying specific cutting pressure by cutting area. Since ploughing force is caused from dullness of a tool, its magnitude is constant if depth of cut is bigger than a certain value. Using the linearity of chip removing force to cutting area and the constancy of ploughing force regardless of depth of cut which is over a certain limit each force is separated from measured cutting force and used to establish cutting force model. New rotation matrix to convert the measured cutting force in reference axes into the forces in cutter axes is obtained by considering that tool angles are projected angles from cutter axes to reference axes.. Spindle tilt is also considered far the model. The predicted cutting force estimated from the model is in good agreement with the measured force.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.135-142
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• 2001

This study discusses frequency analysis based on the frequency spectrum and process characterization in orthogonal cutting of Fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester(GFRP) was used as workpiece The present method employs a force sensor and the signals from the sensor are processed using the fast Fourier transform(FFT) technique. The experimental correlations between the different chip formation mechanisms and power spectrum me established. Effects of fiber orientation, cutting parameters and tool geometry on the cutting mechanisms me also discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1042-1047
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• 2001

A mechanistic model is developed to predict the thrust force and cutting torque of drilling process including wear. A mechanistic oblique cutting force model is used to develop the drilling force model. The cutting lips are divided into small elements and elemental forces are calculated by multiplying the specific cutting pressure with the elemental chip area. The specific cutting pressure is a function of chip thickness, cutting velocity, rake angle and wear. The total forces are then computed by summing the elemental forces. Measured cutting forces are in good agreement with the simulated cutting forces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.608-611
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• 2002

We developed low resistance drum that is used in sawdust machine in this research. The existent drum have two dimensional cutting form(orthogonal cutting) when see cutting pattern of saw cutter and wood, cutting resistance is big and cutting power is cost much, and also, vibration happens extremely. To improve this shortcoming, we developed helical type low cutting resistance drum for three dimensional cutting possible, decreased vibration and cutting resistance of sawdust machine, and improve productivity and sawdust ventilation. Also, a developed drum is mounting in sawdust machine, it is sold by product.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.345-356
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• 2013

Numerical simulation on rock cutting by a TBM disc cutter was carried out using SPH (Smoothed Particle Hydrodynamics) code. AUTODYN3D, a commercial software program based on finite element method, was used in this study. The three-dimensional geometry of a disc cutter and a rock specimen were modeled by Lagrange and SPH code respectively. The numerical simulation was carried out for Hwangdeung granite for 10 different cutting conditions. The results of the numerical simulation, i.e. the relation between cutter force and failure behavior, had a good agreement with those from LCM test. The cutter forces measured in the numerical simulation had 10% deviation from the LCM test results. Moreover, the optimum cutter spacing was almost identical with the experimental results. These results indicate that SPH code can be successfully used had applicability for simulation on rock cutting by a TBM disc cutter. However, further study on Lagrange-SPH coupled modelling would be necessary to reduce the computation time.