The specification of I-beam is expressed in centimeters of waist width, such as the waist width of No.10 I-beam, which is 10cm. The types of I-beams include hot-rolled ordinary I-beams, lightweight I-beams, and wide parallel leg I-beams (H-beams). The waist width of hot-rolled ordinary I-beams in China is 100-630mm, and the inclination of the inner wall of the legs is 1:6. The pass system for rolling I-beams includes direct rolling pass system, oblique rolling pass system, and mixed pass system. In addition, special rolling methods can also be used for I-beams.
Hybrid hole system. According to the characteristics of rolling mills and products, in order to fully utilize the advantages of their respective systems and overcome their shortcomings, hybrid pass systems are often used, that is, a combination of two or more systems. For example, the finished hole and the front hole of the finished product use a straight leg diagonal rolling pass system, while other pass types use a curved leg diagonal rolling system; Alternatively, a direct rolling system can be used for rough rolling holes, and straight leg oblique piercing holes can be used for the last 3-4 finishing holes.
Special rolling method. When it is difficult to roll the required I-beam using the usual rolling method due to certain reasons, a special rolling method can be used to fully utilize the techniques of uneven deformation and pass design. For example, when the cross-section of the steel billet is narrow and wider I-beams are required to be rolled, the wave rolling method can be used; For example, when the billet is wider and smaller I-beams are required to be rolled, negative spread rolling can be used.
Direct rolling pass system. The direct rolling pass system refers to a pass system in which the two open legs of the I-beam pass are located on the same side of the roll axis, and the waist is parallel to the roll axis.
Cross rolling pass system. This pass system refers to the two open legs of the I-beam pass that are not on the same side of the waist at the same time, and the waist has an angle with the horizontal axis.