(1) Because the high rigid section steel made of high strength steel sheet has great inertia moment and bending modulus, especially because of the requirement of application that the consumption of cold bending process should be stopped after pre-punching, it will make the difference between the data surface smoothness and the data edge size. Therefore, it is requested that more lateral positioning and installation be needed in the design of cold bending pass of this kind of high strength structural steel sheet, so as to design reasonably. Pass, reasonable arrangement of roll clearance, etc., to ensure that the data entering each pass do not deviate and eliminate as much as possible the influence of the difference of data surface smoothness and data edge size on the shape of subsequent cold bending forming; Another prominent feature is that the springback phenomenon of high strength structural steel sheet is serious, and springback will cause arc edge, which must be corrected by over bending and over bending angle. It is difficult to control, and the adjustment and revision of demand are stopped in the process of consumption debugging.
(2) More moulding passes are needed. In roll cold bending process, the main processing process is bending deformation. In addition to the slight thinning of the bending angle, the thickness of deformation data is assumed to remain unchanged during the forming process. In pass design, attention should be paid to the rational distribution of deformation, especially in the first and the latter routes, the deformation is not too large. In addition, the side roll and over-bending roll can be used to stop the pre-bending of profiles, and make the neutral line of profiles section coincide with the neutral line of waste profiles, so as to balance the upper and lower forces of profiles, thus preventing the longitudinal bending. If longitudinal bending is found in the process of processing, local rolls can be added according to the actual situation, paying special attention to the following several routes.
Other measures, such as using straightener to stop straightening, changing the distance between racks, using idlers and adjusting the clearance of rolls in various sorties, can reduce or eliminate the longitudinal bending. It should be noted that skilled technology is needed to reduce the need for longitudinal bending by adjusting the roll clearance of each sortie.
(3) Controlling the speed of roll cold bending and adjusting the pressure of forming roll should be appropriate, minimizing fatigue cracks in repeated cold bending, stopping smoothing and cooling properly, further reducing the generation of thermal stress cracks, etc. Controlling the bending radius, i.e. the bending radius should not be too small, otherwise the appearance of products is prone to cracks. Aiming at the delayed fracture of high strength sheet in cold bending process. For example, in order to satisfy the requirement of structural design, it is proposed to optimize the section shape on the premise of satisfying the requirement of mechanical design of data, such as increasing the radius of bending angle, reducing the cold bending angle or increasing the section shape.
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