During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to impr...During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.展开更多
The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple ...The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.展开更多
Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabr...Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabrication technique.Metal thin film resistors on the top of dielectric layer were used to analogize the multiple hot-spots in the modeling IC device.The measured temperature rise with multiple hot-spots agrees well with the predictions given by the superposition calculations.With the help of the superposition strategy,thermal management of IC device can be significantly simplified by decomposing the system into sub-systems and optimizing each part individually.The influence coefficients in the superposition strategy extracted from the experimental measurement offer the IC designers a useful engineering tool to facility the thermal optimization and evaluate the thermal performance of IC devices.展开更多
基金Work supported by the Second Stage of Brain Korea 21 ProjectsProject(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE) of Korea
文摘During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.
文摘The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.
基金supported by the National Science and Technology Major Project of China(Grant No.2009ZX02038-02)the Doctoral Fund of Ministry of Education of China(Grant No.20130001110006)
文摘Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabrication technique.Metal thin film resistors on the top of dielectric layer were used to analogize the multiple hot-spots in the modeling IC device.The measured temperature rise with multiple hot-spots agrees well with the predictions given by the superposition calculations.With the help of the superposition strategy,thermal management of IC device can be significantly simplified by decomposing the system into sub-systems and optimizing each part individually.The influence coefficients in the superposition strategy extracted from the experimental measurement offer the IC designers a useful engineering tool to facility the thermal optimization and evaluate the thermal performance of IC devices.
