An optimal forming process of metal membranes for welding bellows

• Main Authors: Alen Liao, 廖訂綸
• Other Authors: 溫富亮
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/57066417897697422492

碩士 === 聖約翰科技大學 === 自動化及機電整合研究所 === 96 === Welded bellows, a flexible part which is necessary component in vacuum equipment, is studied in this paper. The Taguchi method is used to obtain the optimal processes of forming metal membranes for welded bellows. There are two types of important processes would be discussed: design the press die and functional measurement for all of bellows. A lot of interactive effects among every step in the manufacturing process for welded bellows, i.e., from membrane forming, welding to bellows’ functional testing. In the forming process, initially the single press die was used in the forming, however some problems were occurred during the forming; hence a compound die instead of. The compound die combined PU rubber (Polyurethane) is successful to achieve the forming for particular membrane’s profiles. Also the continuous die is developed to finish the goal of mass production. Next we also discuss that the pressure variation of PU rubbers during pressing how to affect the diameter of metal membranes. When the membrane dimension after forming could not reach the request of accuracy, it would cause the membrane’s welded failed. Therefore, when the press die was designed by engineers, the amount of spring back of the metal membrane is considered. In addition, referred to relative papers, it is necessary to optimize the profile design for the press die and forming metal membranes. To construct of the welded bellows, the first step is to weld the inner circle of membranes (membrane A and B) to be the pair of membranes, and then to weld the outside circle of the pair. When the bellows reached the specified length, at last, it would be weld on the plane part and connection board to complete a desired bellow. Therefore, the design of a jig and a fixture for welding purpose must base on the membrane dimensions, these tools could be alignment the accuracy position to complete and accomplish the welding process. After finishing the whole part, the measurement and testing for AM 350 welded bellows shall be implemented; usually, AM 350 material needs heat treatment before strength testing. The testing result must be compared to the commercial product bought from the trading market. Next, the micro-Viker’s hardness testing would be performed on a piece of AM350 metals via a wire cutting after heat treatment. The required testing for a well design and manufacturing welded bellow includes the life duration and functional quality. The testing equipment for the life duration consists of a vacuum valve as the testing carrier or loader, a cylinder as an actuator, a vacuum pump to generate a negative pressure environment, a vacuum gauge for the pressure monitoring, and other pipes and accessories. For life duration testing, the welded bellow is reciprocated in extension-shrinkage motion at a negative pressure environment and is detected by a vacuum gauge to determine the leakage or broken status of the welded bellow. If the vacuum gauge indicated the pressure is under the specified value, it means the using life of welded bellows coming to the end. Keywords: welded bellow, die pressing, vacuum technology