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Cold bending is a metal processing method in which metal sheets and strips are mechanically bent at room temperature into profiles of certain shapes and sizes. Its products are known as cold-formed profiles. The advantages of cold bending are: it can produce a variety of ultra-thin, ultra-wide and complex shapes, and these shapes cannot be produced by rolling; save metal materials; the product has good mechanical properties.

Cold bending is a metal processing method in which metal sheets and strips are mechanically bent at room temperature into profiles of certain shapes and sizes. Its products are known as cold-formed profiles. The advantages of cold bending are: it can produce a variety of ultra-thin, ultra-wide and complex shapes, and these shapes cannot be produced by rolling; save metal materials; the product has good mechanical properties.

Metal plastic working method used to bend metal sheets and strips into shapes (or parts) and welded tubes at room temperature (see roll forming). Due to the large output of profiles and welded pipes produced by continuous roll bending, the cold bending deformation in the narrow sense refers to this specific bending deformation.

One published report on cold-formed profiles was that in 1855, riveted I-beams were used in the construction of an office building in New York. In 1910, the United States built a continuous roll forming device. Since then, the production of cold-formed profiles has been vigorously developed. Compared with hot-rolled steel, cold-formed steel has accurate size, smooth shape, hot-rolled can not produce special-shaped cross-sectional shape, under the same weight has good bending and torsion resistance. Therefore, the use of cold bending profiles can save more than 30% of the metal. In addition, the production method is simple and the equipment investment is small. Therefore, the production of cold-formed profiles continues to develop. In general, cold-formed steel in advanced steel producing countries accounts for 2% to 4% (up to 5%) of the total rolled products.

It can be divided into three types: the single sheet production mode of bending a single sheet into a single profile, the coil production mode of the whole coil with steel as raw material to produce profiles, and the continuous production mode of head and tail welding with coil as raw material. The continuous production mode has been more developed because of its good dimensional accuracy and high productivity. The typical equipment composition and arrangement of continuous cold-formed steel is shown in Figure 3. No matter which production mode is adopted, the whole process is divided into three stages: raw material preparation, molding and finishing.

The process flow of general open cold bending profile is as follows:

Strip coil → slitting → feeding → uncoiling → straightening → cutting head → butt welding → silo → forming → straightening → cutting → inspection and collection → packing → weighing → storage.

The process flow of closed cold-formed steel is as follows: strip coil → longitudinal shearing → feeding → uncoiling → straightening → cutting head → butt welding → material storage in accumulator → formation → high frequency welding → deburring → cooling → straightening → cutting → inspection and collection → packing → weighing → storage.

If additional processes such as punching, indentation and torsion bending are added to the production line, various special-shaped cold-formed profiles can be produced.