스피닝 가공법을 이용한 표준규격 엘보 성형공정 개발에 대한 연구

Abstract

Fittings are parts used for piping direction and flow control and widely used in various industrial fields such as petrochemical and plant. Elbow is a kind of fitting that changes the length and direction of pipes and are widely used as core parts of pipe system. Elbow is in various standards for different angles and dimensions. In the conventional press forming process, the pipe material is produced to insert into the inner and outer mold and extruded with hydraulic cylinder. However, press forming process is required to high load due to extrusion forming, therefore, a new forming process should be required. This paper introduces spinning manufacturing method as the elbow forming process which minimize the molds and reduce the forming load for world's first. Elbow was selected by a 4″90°elbow that is commonly used in the field. First, it was performed reverse design and analysis of the conventional press forming process, and confirmed the maximum load value, the change in thickness of the forming elbow, and the satisfaction of the minimum and maximum thickness values. And through the analysis of the elbow mechanism, it was confirmed the straightness of the pipe to maintain its original shape when it was formed curved shape. It was confirmed that elbow forming is possible by using spinning process without outer mold, and verified that the maximum forming load is reduced compared with conventional forming press. However, both the analysis and the test results have confirmed that the elbow cannot be formed up to 90°due to buckling in the straight part. It was carried out the research by applying a guide on the straight part to prevent the buckling, and succeeded in forming the aimed 90°elbow. The deformation according to pipe feeding length was investigated. It is shown that large strain are generated at the inner curved region. And it was measured the thickness and confirmed that it meets the reference thickness value. The maximum forming load value is 113 tons, which means that it can be formed to 19.9% of the conventional press forming process.