| Summary: | 博士 === 國立中央大學 === 機械工程學系 === 103 === The purpose of this paper is to investigate the effect of ultrasonic vibration to the process of metal forming. The three main processes in the investigation are the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and equal-channel angle extrusion with ultrasonic vibration to study the characteristics between mold and workpiece and to analyze the influence of ultrasonic vibration.
The paper is divided into four themes, including the design of test equipment with ultrasonic vibration, the design of shearing mold with ultrasonic vibration and the design of ECAE mold with ultrasonic vibration. Using finite element method with ultrasonic processing theory to mold design for the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and ECAE with ultrasonic vibration are successfully applied to the relevant tests.
First, In the investigation of the shear with ultrasonic vibration, the die clearance, the shearing speed and the feeding angle are the three factors with different levels in experiment design. The traditional shearing process and shearing process with ultrasonic vibration are two groups into discussion with RSM(Response surface methodology, RSM). The results showed that low die clearance and high feeding angle can reduce burr formation more due to the characteristics of dynamic vibration.
Secondly, with adjustable working curve in servo press combined with punch speed and vibration amplitude are the three factors with different levels. The RSM is used to investigate the effect on the deep drawing process with ultrasonic vibration. The results showed that the punch load and the friction force could be reduced with the appropriate process of ultrasonic amplitude and working curve. It also can increase the material limitation in the deep drawing process. The characteristic of the dynamic frictional stress with ultrasonic vibration is the main reason to improve the product quality and enhance the economic process.
Finally, the influence of ECAE with ultrasonic vibration is discussed. The results showed that the maximum load decreased with the increasing ultrasonic amplitude in favor of using the punch. The hardness of workpiece can also increase with the increasing ultrasonic amplitude. The manufacturing process is shown in ECAE can indeed strengthen the mechanical strength of the material. The surface roughness of the workpiece can be reduced with the increasing ultrasonic amplitude. It showed that the lubricant in the interface can get better distribution and effect to improve the conditions of friction. However, when speed is greater than a certain critical drawing speed, the friction effect of ultrasonic vibration will almost completely disappear in the use of finite element method to analyze the result.
The paper is investigated in the mold design with ultrasonic vibration, the shear with ultrasonic vibration, the deep drawing with ultrasonic vibration and ECAE with ultrasonic vibration. The paper can also understand the characteristics of different working process as a result of possible reference for future study of the ultrasonic assisted forming.
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