• Geomechanics and Engineering
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• 제37권1호
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• pp.73-84
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• 2024

Owing to the high strength and abrasive characteristics of cobble-boulders, cutters are easily worn and damaged during shield tunneling, making construction inefficient. In the present work, the stress on the ripper and scraper on the cutterhead was analyzed by the PFC3D-FLAC3D coupling model of shield tunneling to get insight into the performance of the cutterhead for cutting underground cobble and boulders. The numerical calculation results revealed that the increase in trajectory radius leads to a rising stress on the cutters, and the stress on the front cutting surface is greater than that on the back of the cutters. Moreover, the correlation between cutter wear and stress is revealed based on field measurement data. The distribution of the cutter stress is consistent with the cutter wear and breakage characteristics in actual construction, in which more extensive cutter stress is exhibited, extreme cutter wear appears, and more cutter breakage occurs. Finally, the relationship between the cutterhead opening area's layout and cutter wear distribution was investigated, indicating that the cutter wear extent is the most severe in the region where the radial opening ratio dropped sharply.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.666-675
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• 1993

In order to prevent bodily injuries frequently suffered in using bush cutters, especially from spattered stones, we developed a unique new cutting system equipped with a fixed blade on top of the rotary blade, and checked into the mowing performance of the cutter. From experimental test of mowing efficiency and measuring test of physical stress (O$_2$ consumption and heartbeat rates) , the new cutting system with a fixed blade proved that it keeps good cutting performance with lower peripheral speed of the rotary blade(22m/sec), compared to that of ordinary cutting blade, yielding more safety in operation. Weight of the cutter head is, however, heavier than that of ordinary machine by about 70% which increased a physical stress on the operator with slightly faster heartbeat rates. In mowing along edge of concrete wall, the operator enjoyed using the cutter with no anxiety , owing to function of the fixed blade.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.245-248
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• 2004

The press cutter is productive equipment that practically manufactures materials such as fabrics, papers, films, leathers, rubbers etc. into the desired shapes using cutting method. Plate cutting process is one of the primary energy absorbing mechanisms in a grounding or collision event. The cutting mechanism is complicated and involves plastic flow of plate in the vicinity of the tip, friction between wedge and plate, deformation of plate. In this paper, we studied the effect of friction between cutter and plastic sheet for producing precise and superior products. The press cutter is analyzed numerically using MARC finite element program according to the variation of friction coefficients. The FEM results showed that normal stress, equivalent cauchy stress, normal total strain, equivalent total strain are good when friction coefficient is 0.0 and shear stress, shear total strain are good when friction coefficient is 0.8.

• 품질경영학회지
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• 제44권4호
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• pp.935-949
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• 2016

Purpose: This study attempts to find out the optimum condition of the rotary cutter making pellet in the footwear outsole process. The pellets are used in the process of outsole rubber fabrication to reduce cycle time and save raw material. Methods: Computer simulations are used to analyze the maximum stress in the rotary cutter after designing a variety of cutter shapes. Taguchi method is used to identify the robust condition of the cutter. In $L_{18}$ orthogonal array, the control factors such as knife width, twisted angle, number of knives, diameter, knife depth and supported angle are considered and noise factors like assembly tolerance and amount of antifriction are allocated. Results: It is found that the most important factors to reduce maximum stress in the cutter are supported angle and diameter. Using Tacuchi's results, we can reduce 70% cycle time and 9% raw material compared to the traditional method using cutting die. Conclusion: When designing the rotary cutter, the best conditions are the diameter at its maximum allowable value and supported angle in the boundary of machine inner space.

• 한국터널지하공간학회 논문집
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• 제16권2호
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• pp.181-191
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• 2014

본 연구는 선형절삭시험 중에 동일한 커터 링 형상을 가진 더블디스크커터와 싱글디스크커터에 발생하는 커터작용력과 각 디스크커터 축에 발생하는 축응력 및 토크를 평가하였다. 선형절삭시험 결과, 선형절삭실험 중에 발생한 더블디스크커터의 연직력과 회전력의 평균값은 싱글디스크커터의 약 두 배 내외인 것으로 측정되었다. 더블디스크커터의 축에 작용하는 축응력의 평균값 역시 연직력과 마찬가지로 싱글디스크커터의 두 배 정도로 나타났지만, 토크의 경우에는 전체적으로 낮은 측정값을 보여 비교의 의미가 없는 것으로 판단되었다. 하지만 더블디스크커터의 연직력의 평균값이 직경 432 mm(17인치) 디스크커터의 허용하중을 상회하기 때문에 테이퍼 롤러 베어링의 내구성능에 대한 검토가 필요한 것으로 판단되었다. 또한 더블디스크커터 축에 작용하는 축응력은 싱글디스크커터의 약 두 배 정도로 발생하였지만, 일반적으로 사용하는 디스크커터 축 재료의 항복강도를 고려할 때 적용 상에 문제가 없는 것으로 나타났다.

• Tribology and Lubricants
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• 제21권4호
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• pp.185-192
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• 2005

The press cutter is productive equipment that practically manufactures mechanical components and polymer-based materials such as fabrics, papers, films, leathers, and rubbers into the desired shapes using a press cutting tool. The plate cutting process is one of the primary energy absorbing mechanisms in a grounding or collision event between a press cutter and a material on a die. The cutting mechanism is complicated and involves plastic flows of a plate in the vicinity of the tip, friction between the wedge and the plate, deformation of the plate. In this paper, we studied the effect of friction between cutter and plastic sheet far producing precise and superior products. In this paper, the press cutter is analyzed numerically using MARC finite element program for a optimization design of a press cutter. The FEM computed results show that the maximum von Mises stress is concentrated on the tip of a press cutter, which may lead to the edge wear or impact wear of the sharp cutter. Based on the FEM result and Taguchi's experimental design method, the optimized design model 9 for a press cutter is recommended as a best one.

• 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.

• 한국터널지하공간학회 논문집
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• 제15권3호
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• pp.225-235
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• 2013

TBM의 암반 굴착도구인 디스크커터의 작용력은 TBM의 설계와 굴진성능 평가를 위해 핵심적인 항목이다. 본 연구에서는 디스크커터 링의 형상에 따른 디스크커터 작용력의 차이를 실물 선형절삭실험에 의해 실험적으로 분석하였다. 또한 절삭실험 중에 발생하는 커터 링의 변형률을 계측하여 커터 링의 강성을 추정하였다. 분석결과, V형상의 디스크커터를 사용하게 되면 동일한 절삭조건에서 커터 관입깊이를 증가시킬 수는 있지만, 커터의 회전방향으로 큰 응력이 작용하는 것으로 나타났다. 또한 커터 작용력을 예측모델에 의해 추정할 경우에는, 디스크커터의 형상과 관련된 변수들을 고려할 수 있는 모델을 사용하는 것이 타당함을 알 수 있었다.

• 한국생산제조학회지
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• 제8권5호
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• pp.25-29
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• 1999

Machining process introduces thermal deformation of a cutter which affects the surface finish of the workpieces. By measuring the temperature distribution f the cutter thermal stress and deformation of the cutter are simulated. In addition surface roughness of workpiece is simulated by the surface-shaping system. The result shows that thermal deformation deteriorates the surface roughness.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.97.2-101
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• 1998

Machining process introduces thermal deformation of a cutter, which affects the surface finish of the workpieces. By measuring the temperature distribution of the cutter, thermal stress and deformation of the cutter are simulated. In addition, surface roughness of workpiece is simulated by the surface-shaping system. The result shows that thermal deformation deteriorates the surface roughness.