The Effect of Drill Built-Up Edge on the Torque

드릴링시 드릴에 구성인선의 발생을 고려한 경우와 고려하지 않은 경우에 주절삭날에 작용하는 토오크를 각각 구하고 이 값들이 전체토오크에 차지하는 비율을 고려하여 전체토오크에 대한 비를 구했다. 그 결과 구성인성을 고려해서 실제유효경사각을 이용하여 구한 전체토오크가 구성인선의 발생을 고려하지 않고 유효경사각과 수직경사각을 사용해서 구한 전체토오크 보다 약 5%와 10%가 작다는 것을 알았다.In drilling, torques acting on the main cutting edges are calculated under the conditions with and without the built-up edge on a drill respectively and by considering the percentages of these values to the total torque, the ratios of the total torque of the former to the total torques of the latter are computed. The result is obtained that the total torque computed by the real effective rake angle with the built-up edge is about 5% and 10% less than the total torques by the effetive rake angle and the normal rake angle without the built-up edge.In drilling, torques acting on the main cutting edges are calculated under the conditions with and without the built-up edge on a drill respectively and by considering the percentages of these values to the total torque, the ratios of the total torque of the former to the total torques of the latter are computed. The result is obtained that the total torque computed by the real effective rake angle with the built-up edge is about 5% and 10% less than the total torques by the effetive rake angle and the normal rake angle without the built-up edge

A Study on the Forming of Quadrangular Cups with the Acute and Obtuse Corner Angles

사다리꼴용기와 정사각용기의 깊이를 45㎜까지 성형하였다. 용기의 코너플랜지의 변위와 변형률을 FEM과 실험을 병행하여 해석하였다. 사다리꼴용기의 코너플랜지에서 변형률을 정사각용기의 코너플랜지에서 변형률과 비교·검토하여 다음과 같은 결과를 얻었다. (1) 코너플랜지에 전단변형률이 발생하여서 변형률의 크기를 비교하기 위해서는 유효변형률을 사용하는 것이 필요하다. (2) 코너각이 72˚인 사다리꼴의 긴변을 포함한 코너플랜지의 유효변형률의 평균값은 정사각용기의 코너플랜지에서 유효변형률의 평균값과 거의 같았다. (3) 코너각이 108˚인 사다리꼴의 짧은 변을 포함한 코너플랜지의 유효변형률의 평균값은 정사각용기의 코너플랜지에서 유효변형률의 평균값보다 작았다.Trapezoid cups and square ones have been deep-drawn to 45㎜ in depth. Displacements and strains have been analysed respectively by FEM and experiment. Strains and effective strains in the corner flanges of trapezoid cups have been compared with those in square cups. The results have shown that because of shear strains in the corner flange, it is necessary to adopt effective strain for comparing of strains, the mean value of effective strains in the corner flange with the corner angle of 72˚des is nearly equal to those with the corner of a right angle and the mean value of effective strains with the corner angle of 102˚is smaller than those with the corner of a right angle.Trapezoid cups and square ones have been deep-drawn to 45㎜ in depth. Displacements and strains have been analysed respectively by FEM and experiment. Strains and effective strains in the corner flanges of trapezoid cups have been compared with those in square cups. The results have shown that because of shear strains in the corner flange, it is necessary to adopt effective strain for comparing of strains, the mean value of effective strains in the corner flange with the corner angle of 72˚des is nearly equal to those with the corner of a right angle and the mean value of effective strains with the corner angle of 102˚is smaller than those with the corner of a right angle

The Effect of Drill Flank-Wear on the Cutting Resistance

본 논문에서는 drill의 측면마모가 torque와 thrust에 미치는 영향에 관해서 연구하였다. 측면마모의 주절삭날에 따른 분포를 2차원 절삭에 적용되는 Taylor's too-life equation을 이용해서 ??로 가정하고 torque와 thrust에 관한 식을 유도하였다. 그 결과 wear land가 4.2×10??인치 정도에 도달했을 때 flank wear에 의한 torque와 thrust가 전체 torque와 thrust에 각각 약 10%, 2%에 해당되었다. 그러므로 절삭동력을 구할 ?? flank wear에 의한 영향을 고려하여야 한다.In the present paper, it is studied on the effect of flank wear on the cutting resistance in drilling. The equations for torque and thrust are derived from the assumption that the profile of flank wear along the main cutting edge is ??. This expression is obtained by using the Taylo'r tool-life wquation applied to the porhogonal cutting. The result of this paper is that 10% of total torque is the torque due to falnk wear as wear land is reached at 4.2×10?? in. and the effect of thrust is 2% of tatal thrust at the same time. Therefore, the effect of flank wear must be considered in obtaining the cutting tesistance.In the present paper, it is studied on the effect of flank wear on the cutting resistance in drilling. The equations for torque and thrust are derived from the assumption that the profile of flank wear along the main cutting edge is ??. This expression is obtained by using the Taylo'r tool-life wquation applied to the porhogonal cutting. The result of this paper is that 10% of total torque is the torque due to falnk wear as wear land is reached at 4.2×10?? in. and the effect of thrust is 2% of tatal thrust at the same time. Therefore, the effect of flank wear must be considered in obtaining the cutting tesistance

Effects of Working Conditions on Deformed Layer of STD11 in Wire-cut EDM

본 연구에는 열처리된 금형강(STD11)을 사용하여 가공조건으로 가공전류, 와이어장력, 이송속도 등을 변화시켜 변질층 깊이와 경도를 현미경 조직사진을 통한 조직변화의 고찰과 경도시험을 하여 검토하였다. 그 결과 다음과 같은 결론을 얻었다. (1) 변질층의 경도는 가공전류 3A, 와이어장력 1500gf 및 이송속도 80%일 때 Hv685(HRC59.5)로 가장 높았다. (2) 변질층의 깊이는 가공전류 3A이며 와이어장렬 1500gf이고, 이송속도 80%일 때 약 6㎛로서 가장 낮았다.In this study, deformed layer thickness, hardness and microstrucre of deformed layer were investigated with the variations of peak current, wire tension and feed rate, and the material is heat-treated STD11. The results have shown that (1) deformed layer thickness is minimum at 3A, 1500gf, and 80% and (2) hardness is the highest at peak current 3A, wire tension 1500gf and feed rate 80%.In this study, deformed layer thickness, hardness and microstrucre of deformed layer were investigated with the variations of peak current, wire tension and feed rate, and the material is heat-treated STD11. The results have shown that (1) deformed layer thickness is minimum at 3A, 1500gf, and 80% and (2) hardness is the highest at peak current 3A, wire tension 1500gf and feed rate 80%

A Study on the Mechanical Properties of Weld Zones in Plazma Arc Welding of Dissimilar Metals

이종(異種)금속재료의 용접은 화학플랜트, 해상구조물, 조선, 항공 등의 분야에서 금속접합 방법으로 적용시키는 연구가 활발히 진행되고 있다. 본 연구에서는 일반 구조용 압연 강재(SS 400)와 오스테나이트계 스테인레스 강재(STS 304)를 사용하여 플라즈마 아크용접으로 맞대기 이음 용접을 한 후 모재부(BM), 열영향부(HAZ) 및 용착금속부(WAZ)의 인장, 경도 및 굽힘 시험으로 기계적 특성과 현미경 조직사진을 통한 금속조직의 변화를 고찰 검토하였다.Tensile test, micro vickers hardness test, bending test and microstructure inspection were performed and the mechanical properties and microstructures investigated.Tensile test, micro vickers hardness test, bending test and microstructure inspection were performed and the mechanical properties and microstructures investigated

Effects of Corner Cut on the Formability of Trapezoid Cup Drawing

본 논문은 사다리꼴 단면을 갖는 용기의 성형에서 4각블랭크의 코너컷방법을 제시하였다. 또한 4각블랭크와 코너컷을 한 블랭크의 성형성을 비교하였다. 실험 결과에 의하면 사각 블랭크의 경우 단변부의 코너와 중앙에서 변형률의 최대가 1.24와 0.25이었고, 코너컷을 한 경우는 최대변형률이 0.12와 0.16으로 상당히 감소하였음을 알 수 있었다.A method of corner cut for a rectangular blank in trapezoid cup drawing is proposed. The formability of a rectangular blank is compared with that of a corner cut blank. The experimental results has shown that maximun strains in the former were 0.24 and 0.25 at the corner and center of short side, but in the latter 0.12 and 0.16 and that the strain distribution considenally decreased.A method of corner cut for a rectangular blank in trapezoid cup drawing is proposed. The formability of a rectangular blank is compared with that of a corner cut blank. The experimental results has shown that maximun strains in the former were 0.24 and 0.25 at the corner and center of short side, but in the latter 0.12 and 0.16 and that the strain distribution considenally decreased

A Study on the Tooth Root Stresses of a Spur Gear

물림율이 2以上일 때 平齒車의 한 개의 齒가 물리기 始作하여 끝날 때까지 分擔하는 荷重과 이뿌리에 發生하는 應力을 光彈性實驗으로 測定하였다. 그리고 이 結果를 使用하여 決定한 齒의 크기는 一般的인 設計値보다 約 25%정도 작게 할 수 있었다.The partial load acting on a tooth and the stress at the tooth root of a spur gear, were measured using the photoelastic apparatus when the contact ratio is greater than 2. The result shows that the gear would be designed about 25% smaller than conventionally used one when the contact ratio is grater than 2.The partial load acting on a tooth and the stress at the tooth root of a spur gear, were measured using the photoelastic apparatus when the contact ratio is greater than 2. The result shows that the gear would be designed about 25% smaller than conventionally used one when the contact ratio is grater than 2

An Experimental Study on the Visco-Plastic Behaviors of SPCC steel

SPCC강에 대한 점소성 거동의 특성을 Perzyna 점소성 모형을 기준으로 실험적으로 조사하였다. 점소성 구성방정식을 미소변형 및 유한변형이론에 맞추어 표현하고, 각 경우에 대한 ?걍荇撰? 및 정적항복함수를 구하였다. 여러가지 변형율속도하에서 인장시험 결과로 부터 물질상수 및 정적항복함수를 결정하기 위한 자료처리 방안이 제시되었다.The characteristics of Visco-Plastic behaviors of SPCC steel are investigated empirically based on the Visco-Plastic model proposed by Perzyna. Visco-Plastic constitutive equations are expressed according to both infinitesimal and finite deformation theories, and material constants and static yield function are obtained in each case. A method of data regression is proposed for determining the material constants and static yield function from the results of tensile test under various strain-rate.The characteristics of Visco-Plastic behaviors of SPCC steel are investigated empirically based on the Visco-Plastic model proposed by Perzyna. Visco-Plastic constitutive equations are expressed according to both infinitesimal and finite deformation theories, and material constants and static yield function are obtained in each case. A method of data regression is proposed for determining the material constants and static yield function from the results of tensile test under various strain-rate

Decreased expression of sirtuin 6 is associated with release of high mobility group box-1 after cerebral ischemia

Sirtuin 6 (SIRT6) belongs to the sirtuin family of NAD+-dependent deacetylases and has been implicated in the regulation of metabolism, inflammation, and aging. Here, we found that SIRT6 was predominantly expressed in neuronal cells throughout the entire brain. Ischemia models using transient middle cerebral artery occlusion in rats and oxygen/glucose deprivation (OGD) in SH-SY5Y neuronal cells showed that ischemia reduced SIRT6 expression and induced the release of high mobility group box-1 (HMGB1) from cell nuclei. The reduced expression of SIRT6 via treatment with SIRT6 siRNA dramatically enhanced the OGD-induced release of HMGB1 in SH-SY5Y cells. Together, our data suggest that SIRT6 may serve as a potential therapeutic target for HMGB1-mediated inflammation after cerebral ischemia.ope