Production method on pipe of thin-spring steel sheet

In plastic working, the research away from the forming of carbon steel sheet in favor of alloy steel sheet is going into high gear. Especially, since products formed by thin-alloy steel sheet can get the equivalent strength to that of thick-carbon steel sheet, it is very useful to reduce the weight of industrial structure and so on. However, on the other hand, it is very difficult to form alloy steel sheet because these materials are of low elongation, high yield, and tensile strength. This paper deals with the production process on cold roll forming that takes advantage of the nature of spring-back of spring steel sheet to make the special pipe. The special pipe is very convenient to transfer because the pipe can wind up like the coil steel sheet [JIS Handbook Steel, 1998; J. JSTP 38 (12) (1997) 443; J. JSTP 38 (12) (1997) 443; JSME Int. J. 1 (2) (1990) 33].