• 한국CDE학회논문집
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• 제2권3호
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• pp.186-194
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• 1997

This paper describes new methods to minimize the cutting time in zigzag milling operation of two dimensional polygonal surfaces. Previous works have been focused on mainly experimental approaches by considering some machining parameters such as, spindle speed, depth of cut, cutter traverse rate, cutter diameter, number of teeth, tool wear, life of tool, and so on. However, in this study, we considered two geometrical factors one by one in order to see the effect separately, which are the length of cut and the number of cutter traverse. In an N-sided concave or convex polygon, an algorithm has been developed which minimize the total length of cut. Also, a heuristic approach was used to minimize the number of cutter traverse.

• International Journal of Precision Engineering and Manufacturing
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• 제4권4호
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• pp.13-18
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• 2003

This paper presents the in-process compensation to control cutter ronout and to improve the machined surface quality. Cutter ronout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by cutter ronout compensation.

• Geomechanics and Engineering
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• 제34권1호
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• pp.103-113
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• 2023

This study focused on understanding the relationship between the design of a tunnel boring machine disc cutter ring and its rock-breaking efficiency, as well as the applicable conditions of different cutter ring types. The discrete element method was used to establish a numerical model of the rock-breaking process using disc cutters with different ring types to reveal the development of rock damage cracks and variation in cutter penetration load. The calculation results indicate that a sharp-edged (V-shaped) disc cutter penetrates a rock mass to a given depth with the lowest load, resulting in more intermediate cracks and few lateral cracks, which leads to difficulty in crack combination. Furthermore, the poor wear resistance of a conventional V-shaped cutter can lead to an exponential increase in the penetration load after cutter ring wear. In contrast, constant-cross-section (CCS) disc cutters have the highest quantity of crack extensions after penetrating rock, but also require the highest penetration loads. An arch-edged (U-shaped) disc cutter is more moderate than the aforementioned types with sufficient intermediate and lateral crack propagation after cutting into rock under a suitable penetration load. Additionally, we found that the cutter ring wedge angle and edge width heavily influence cutter rock-breaking efficiency and that a disc cutter with a 16 to 22 mm edge width and 20° to 30° wedge angle exhibits high performance. Compared to V-shaped and U-shaped cutters, the CCS cutter is more suitable for soft or medium-strength rocks, where the penetration load is relatively small. Additionally, two typical case studies were selected to verify that replacing a CCS cutter with a U-shaped or optimized V-shaped disc cutter can increase cutting efficiency when encountering hard rocks.

• Geomechanics and Engineering
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• 제31권3호
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• pp.249-263
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• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• Journal of Computational Design and Engineering
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• 제3권2호
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• pp.151-160
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• 2016

Cutter-workpiece engagement (CWE) is the instantaneous contact geometry between the cutter and the in-process workpiece during machining. It plays an important role in machining process simulation and directly affects the calculation of the predicted cutting forces and torques. The difficulty and challenge of CWE determination come from the complexity due to the changing geometry of in-process workpiece and the curved tool path of cutter movement, especially for multi-axis milling. This paper presents a new method to determine the CWE for general milling processes. To fulfill the requirement of generality, which means for any cutter type, any in-process workpiece shape, and any tool path even with self-intersections, all the associated geometries are to be modeled as triangle meshes. The involved triangle-to-triangle intersection calculations are carried out by an effective method in order to realize the multiple subtraction Boolean operations between the tool and the workpiece mesh models and to determine the CWE. The presented method has been validated by a series of case studies of increasing machining complexity to demonstrate its applicability to general milling processes.

• 한국기계가공학회지
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• 제11권4호
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• pp.147-153
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• 2012

The demands of the large scale machine tools, for instance, such as planomiller, turning machine, boring machine, NC machine, have been gradually increased in recent years. As the performances of machine tools and/or cutting tools are advanced, it is possible to perform high-speed and high-precision cutting works. The effective treatment of wet chip, which is discharged from cutting works, becomes very important problems. Therefore, this study is forced on the design of large scale machine tools using CATIA V5R18 and analysis of cutter, which is considered as essential equipment in large scale machine tools, using MSC.Nastran & MSC.Patran. Especially, the relations between tolerated load of cutter, driving horse power and rpm of driving shaft in chip processing system are investigated through analysis. As the results, the reliability of design could be improved by evaluating simulated numerical values, it showed that tolerated loads of supported part and edged part of cutter are 87,000N and 14,450N, respectively.

• 한국정밀공학회지
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• 제18권5호
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• pp.130-136
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• 2001

Generally, a metal slitting saw is plain milling cutter with thickness less than 3/16 inch. This is used for cutting a workpiece that high dimensional accuracy and surface finish is necessary. A small thin milling cutter like a metal slitting saw is useful for machining a narrow groove. In this case, built up edge(BUE) is severe at each tooth and affects the surface integrity of the machined surface and tool wear. It is well known that tool geometry and cutting conditions are decisive factors to remove BUE. In this paper, we optimized the geometry of the milling cutter and selected cutting conditions to remove BUE by the experimental investigation. The experiment was planned with Taguchi method based on the orthogonal array of design factors such as coating, rake angle, number of tooth, cutting speed, feed rate. Response table was obtained from the number of built-up edge generated at tooth. The optimized tool geometry and cutting conditions could be determined through response table. In addition, the relative effect of factors was identified bh the analysis of variance (ANOVA). Finally, coating and cutting speed turned out important factors for BUE.

• 한국터널지하공간학회 논문집
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• 제15권3호
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• pp.321-331
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• 2013

이 연구는 TBM의 디스크커터 관입깊이에 대하여 실질적인 현장을 통하여 평가한 것이다. 연구를 위하여 설계시 적용되는 디스크커터 관입깊이에 대하여 검토하였다. 또한 대상 현장에 대한 지반특성에 대하여 검토하고 현장에 투입된 장비에 대한 적용성에 대하여 분석하였다. 특히 장비의 용량분석을 실시하여 적합성에 대하여 평가하였다. 이러한 평가결과와 현장 공사자료를 근거로 실질적인 TBM의 공사량과 굴진속도를 분석하였다. 이 결과로부터 설계시 적용된 TBM의 디스크커터 관입깊이에 대하여 재평가 하였다. 연구 결과로부터 설계시 적용되는 디스크커터 관입깊이는 특히 극경암 지반($S_c$ >150 MPa)에 있어서 적용값의 변경이 필요하다는 것을 명백히 보여주었다.

• 한국기계가공학회지
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• 제7권3호
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• pp.30-35
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• 2008

As demands for being economical, precise drilling process is on the increase. Therefore, the objective of this study is to develop a step cutter that can be controllable through micro dimension and can be changed from separate manufacturing processes of drilling and boring into an integrated one. In order to attain this object the step cutter is designed with a 3D geometric modeling and the design could be modified easily by using parametric modeling methodology. Also, collision is not occurred during manufacturing process because of cutting simulation. The step cutter is assembled by parts made up of 5-axis machining and sintering. Validation tests are accomplished. They show that developed cutter has characteristics such as reduction of machining time as well as the good surface roughness of the machined hole. Indeed, reliability could be obtained from a durability test.

• 한국터널지하공간학회 논문집
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• 제24권6호
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• pp.553-581
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• 2022

TBM (Tunnel Boring Machine)이 터널 산업에 도입된 이후로 안전성과 친환경의 이점으로 TBM의 사용이 전 세계적으로 증가하였다. 암반 및 토사 지반을 굴착하는 TBM 터널에서의 주요 비용 중 하나는 손상되거나 마모된 커터의 교체로 볼 수 있다. 커터의 교체는 시간과 비용에 큰 영향을 끼치는 작업이며 TBM 가동률과 굴진율을 크게 감소시킬 수 있다. 따라서 커터의 수명을 정확하게 평가하는 것은 공기와 비용의 측면에서 매우 중요하다. 그러나 복합 지반을 포함하여 토사 구간, 암반구간에서 커터 마모에 대한 예측은 매우 복잡하고 명확하지 않다. 이에 따라 커터 마모에 대한 다양한 예측 모델이 개발 및 도입되었지만 이러한 불확실성으로 인해 가변적인 결과를 나타낸다. 본 연구에서는 커터 마모 예측 모델을 제시하기 보다는 커터 교체의 설계 및 시공 사례 연구를 소개하고 분석했다. 커터는 지반 조건, TBM 장비 및 운전의 영향을 많이 받으므로 불확실성과 한계를 감안하면 신뢰성 있는 예측 모델을 제안하는 것은 매우 어렵기 때문에 오히려 실제 사례를 분석하고 이에 대한 자료 공유가 더 실용적이다. 커터 교체에 대한 예측과 결과 간의 차이를 확인하고 심도 있게 분석하였다.