What is the process flow of cold bending processing?

Cold bending processing is a method of metal processing where metal sheets and strips are mechanically bent into specific shapes and sizes at room temperature. The products are referred to as cold-formed profiles. The advantages of cold bending include: it can produce various ultra-thin, ultra-wide, and complex shapes that cannot be produced by rolling; it saves metal materials; and the products have good mechanical properties.

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

A public report on cold-formed profiles dates back to 1855, when riveted I-beams were used in the construction of office buildings in New York. In 1910, the United States built continuous rolling forming devices, and since then, the production of cold-formed profiles has developed rapidly. Compared to hot-rolled steel, cold-formed steel has accurate dimensions, smooth appearance, and unique cross-sectional shapes that cannot be produced by hot rolling, as well as good bending and torsional resistance at the same weight. Therefore, using cold-formed profiles can save more than 30% of metal. Additionally, the production method is simple, and equipment investment is low. As a result, the production of cold-formed profiles continues to develop. Generally, cold-formed steel accounts for 2% to 4% (up to 5%) of the total rolled products in advanced steel-producing countries.

It can be divided into three types: the single production mode where a single sheet is bent into a single profile, the coil production mode where whole coils of strip steel are used as raw materials to produce profiles, and the continuous production mode where coils are used as raw materials with head and tail welding. The continuous production mode has developed more due to its good dimensional accuracy and higher production rate. The typical equipment composition and layout for continuous cold-formed steel are shown in Figure 3. Regardless of the production mode used, the entire process is divided into three stages: raw material preparation, forming, and finishing.

The process flow for general open cold-formed profiles is as follows:

Coil of strip steel → Slitting → Feeding → Uncoiling → Straightening → Cutting heads → Butt welding → Material storage → Forming → Straightening → Cutting → Inspection and collection → Packaging → Weighing → Storage.

The process flow for closed cold-formed steel is as follows: Coil of strip steel → Longitudinal shearing → Feeding → Uncoiling → Straightening → Cutting heads → Butt welding → Material storage in accumulator → Forming → High-frequency welding → Deburring → Cooling → Straightening → Cutting → Inspection and collection → Packaging → Weighing → Storage.

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