The cold roll forming means by rolling through many racks of rollers, the coiled material and belt material get formed in transverse and turn to a sheet with specific sectional drawing. It is a producing method to get the sheet with different shape and different model. Buring this process, the sheet get bending deflection only. So only the bending angle parts get attenuated and the thickness of other parts remain unchanged. This is producting method is particularly propitious to products with long appearance and in quantity. It has the advantage of efficient, high-yield, commonly used and non-polluted.

This industry started in 50s or 60s in China, and get flourished in recent years. But until now, it has not come to a system with mature technology. Through years of operating and learning, research and summarize on the cold roll forming, we thought that this industry can divide into following parts: Firstly, from the shape of the sheet, it can be devided to open profiled sheet and closed profiled sheet: form the application, it can be devided to construction sheet series, dedusting anode plate series, cable bridge series, box board series, iron tower in power transmission, garage, doors and windows, goods shelf and daily essentials. It palys an important role in economic growth. Secondly, model calculate method includes the thickness calculate and sheet developed area calculate. The slitting is on the basis of developed area calculate. In production, firstly use the theoretical value to decide the basic size, and make some adjustment by the physical truth. Sometimes, the right algorithm may come out the accurate result. By saying the developed area, it means the neutral layer length, not the concentric layer length. With different thickness and different number of arc, the way of calulate is different. The neutral layer length starts calculating form the 2/3 of the underside and takes the lose of bending parts and stretch into consideration. Using the software to calculate the developed length, the number need to minus the 1%-3% of this number, and for the aluminium sheet, the minus percentage should be higher, like 5%. In this way, the width of the sheet would be more precise.