Process method for manufacturing stainless steel reducer

　　Concentric reducer and eccentric reducer with large diameter can be rolled from sheet metal on the plate rolling machine. This stainless steel reducer has only one radial longitudinal weld. Concentric reducers and eccentric reducers with smaller diameters, as well as reducers of any size and diameter, can only be pressed into the shape of half of the sheet metal through the mold, and then the two halves are assembled and welded into an integral pipe fitting. This stainless steel reducer has two radial longitudinal welds. And the two halves of the eccentric reducer and the reducer elbow need two sets of molds respectively.

　　When forming stainless steel reducer with sheet metal (rolling), cold pressing is generally adopted. Hot pressing can only be used when the capacity of the press is limited. The die size of cold pressing and hot pressing will be slightly different.

　　Manufacturing process of seamless reducer

　　The manufacturing process of concentric reducer is the simplest. Use the pipe with thicker wall thickness as the blank, expand the diameter at one end or use the pipe with equal wall thickness as the blank, or reduce the diameter at one end. Whether it is expanded or shrunk, it is usually pressed with a die. At present, eccentric dies are widely used to press eccentric reducers step by step in China. The eccentric reducers produced by this process with more than three stages will produce serious notch, inner wall bulge, uneven wall thickness and ovality at the eccentric end of the small head. When the eccentric reducer is replaced by the structure obtained by cutting the head of the inclined concentric reducer, because the inclined section is not a circular surface but an elliptical surface, there will be a problem of misalignment between the end face and the straight pipe, which cannot be completely connected. If a new pressing process is adopted, that is, first press the concentric reducer with the concentric die, and then put the pressed concentric reducer into the eccentric die to press the required eccentric reducer, the inner and outer surfaces are smooth, the small end is flat, the wall thickness is uniform, the roundness is qualified, and the raw materials used are less.

　　The rreducer can be formed by the progressive necking of the mold on the basis of the equal-diameter elbow. In order to facilitate the necking, cut off a piece of redundant reducer wall in the area convenient for manual welding on the outer arch of the reducer, and then weld the necking after the necking. Of course, the weld must be subject to strict inspection. In this way, the reducing elbow becomes a pipe fitting with half weld, but the wall thickness is relatively uniform.

　　When the stainless steel reducer is formed by pressing the pipe blank, the large diameter pipe is generally formed by hot pressing and closing, but the small diameter pipe is not suitable for cold pressing and expanding.