Study On Mechanical Expanding Process Of 304 Stainless Steel Spinning Parts

304 stainless steel cylindrical spinning is a product developed by a space academy. Oval cross-section of the tubular parts increase after spinning, it can’t meet the technical requirements for products. And the straightness of product can be also improved. Therefore, the unit of product development put forward the idea that using the mechanical expanding technique to eliminate the phenomenon that forming precision of product ultra difference. The mechanical expanding technique is a kind of commonly used plastic forming process. It has been widely used in eventually forming of the thin-wall spinning pipe, large diameter longitudinal welded pipe, large diameter spiral welded pipe and other large and medium-sized cylindrical parts.In this paper, the mechanical expanding technique of the 304 stainless steel cylindrical spinning with high strength is systematically studied using theoretical analysis, MARC simulation and experiments. The research contents include: the analysis of deformation process and characteristics, the influences of expanding punch contour and process parameters on quality of finish pipe, the mechanical expanding experimental design of 304 stainless steel tube. Through the study found that The deformation process of mechanical expanding of line pipe falls into three stages — “rounding stage”, “expanding stage” and “unloading stage”. The die radius, edge radius, the plastic expanding rate, initial tube ovality and the straightness have different effects on the cross-section ovality, wall thickness distribution, rebound and straightness of the product. Experimental research has been found that the 304 stainless steel tube appears obvious phenomenon of hardening, the yield ratio is more than 0.9, the intensity becomes higher and the plastic becomes worse. Traditional mechanical expanding process is very difficult to shaping for products.