(1) Since the high rigidity steel formed by the high strength plate has a large moment of inertia and flexural modulus, especially due to the requirements of the application, it is necessary to perform cold bending after pre-punching, which will form the material surface flatness and material Due to the difference in edge size, it is required to add more lateral positioning devices in the design of the cold-formed pass for this type of high-strength structural steel plate, reasonably design the pass, and reasonably arrange the roll gap, etc., to ensure that the material entering each pass does not. Deviation and try to eliminate the influence of the difference in material surface flatness and material edge size on the subsequent cold-formed shape; another prominent feature is: the forming springback of high-strength structural steel plates is serious, and the springback will cause When there is an arc edge, it must be corrected by cornering, and the cornering angle is difficult to grasp, so it needs to be adjusted and corrected during the production and debugging process.
(2) More molding passes are required. In the roll forming process, the main processing process is bending deformation. Except for the slight reduction of the bending angle of the product, the thickness of the deformed material is assumed to remain unchanged during the forming process; in the design of the pass, attention should be paid to the reasonable distribution of deformation The amount of deformation, especially in the first pass and the following passes, is not easy to be too large. In addition, side rollers and bending rollers can be used to pre-bend the profile, and the neutral line of the profile section and the neutral line of the finished profile can be overlapped to balance the forces on the top and bottom of the profile, thereby avoiding longitudinal bending. If longitudinal bending is found during processing, some rolls can be added according to the actual situation, especially the latter ones.
Other measures such as straightening with a straightening machine, changing the stand spacing, using idlers, and adjusting the roll gap of each sortie can reduce or eliminate longitudinal bending. It should be noted that the reduction of longitudinal bending by adjusting the roll gap of each pass requires skilled technology.
(3) The control of roll-type cold bending speed and the adjustment of forming roll pressure should be appropriate to minimize repeated cold-bending bending fatigue cracks, and appropriate lubrication and cooling should be carried out to further reduce the generation of thermal stress cracks, etc., and control the bending radius, that is, bending The radius should not be too small, otherwise cracks will easily occur on the surface of the product. In order to meet the structural design requirements, it is recommended to optimize the cross-sectional shape on the premise of meeting the mechanical design requirements of the material. For example, increasing the corner radius, reducing the cold bending angle or increasing the cross-sectional shape is also an effective method.
