Research And Development Of Progressive Edge Bending Forming Process And Mould For Long Circular Tubes

The welded tube is wildly applied in many fields, such as oil mill ,gas transportation,architecture,automobile,transportation, etc.. With the development of these industries, the demand for welded tube is growing rapidly, which impel the evolution of welded tube production enormously. At present, Press Method and Roll Method are the two main methods to form the welded tube. The Press Method is suitable to produce the diversiform products in small-scale production. Contrast to the former, Roll method fits for the mass production of long tubes better. With the demands for functions and diversities getting higher and higher, products beyond the specification of Roll method are demanded more and more. In order to meet these demands, Progressive Edge Bending Method for welded tube was developed, which fits to produce the diversiform long circular tubes in a small-scale production. How to minimize the longitudinal warpage and edge waves is the key step of Progressive Edge Bending Method. In this paper, the reasons why longitudinal warpage and edge waves occur was analyzed and then the assumption that these defects can be suppressed when the length of the edge equals to the length of strip center was proposed. Depending on this assumption, four kinds of tube forming methods were analyzed and the edge bending method was chosen. By the deeper researches, authors not only constructed the auxiliary model, but also educed the mathematic equations of the key curves and the value range of parameters. In Excel, according to the minimum principle, auxiliary table was set up and the curve graph of elongation coefficient of edge was drawn to calculate the optimum value of m, n and K. On the basis of analysis, authors utilized UG to develop a new mould that integrated shearing and sizing units to improve the mould's performance, reduce the floor space and the costs. By analyzing shortages resulted from mould testing, authors proposed series of methods to improve the design, which could produce the eligible welded tube. The authors'assumption and the conclusion were proved by the actual production, and the mould fits to produce the diversiform long circular tubes in a small-scale production.