H-shaped steel production method

H-shaped steel can be produced by welding or rolling. Welding H-shaped steel is to cut strip steel with suitable thickness into suitable width, and weld the flange and web together on a continuous welding unit. Welding H-shaped steel has the disadvantages of high metal consumption, difficulty in ensuring uniform product performance, and limited size specifications. Therefore, H-shaped steel is mainly produced by rolling method. In modern steel rolling production, universal rolling mills are used to roll H-shaped steel. The web of the H-shaped steel is rolled between the upper and lower horizontal rollers, and the flange is rolled simultaneously between the sides of the horizontal rollers and the vertical rollers. Since the flange edge cannot be pressed down by the universal rolling mill alone, it is necessary to set up an edge rolling machine behind the universal rolling mill, commonly known as a flange rolling machine, in order to press down the flange edge and control the flange width. . In the actual rolling operation, the two stands are used as a group to make the rolled piece pass back and forth several times (Figure 2a), or the rolled piece is made to pass through several universal stands and one or two edge rolling end stands. The continuous rolling mill group consists of a certain amount of reduction in each pass to roll the blank into products with required specifications, shapes and sizes. In the flange area of the rolled piece, due to the sliding between the side of the horizontal roller and the rolled piece, the wear of the roll is relatively large. In order to ensure that the rolls can return to their original shape after heavy rolling, the sides of the upper and lower horizontal rolls of the roughing mill unit and the corresponding vertical roll surfaces should have an inclination angle of 3° to 8°. In order to correct the inclination angle of the finished product flange, a finished product universal rolling mill, also called a universal finishing mill, is set up. The side of the horizontal roll is perpendicular to the axis of the horizontal roll or has a small inclination angle, generally not greater than 20′.
When H-shaped steel is rolled with a universal rolling mill, the cross section of the rolled piece can be extended more evenly, and the speed difference between the inner and outer roller surfaces of the flange is small, which can reduce the internal stress and appearance defects of the product. By appropriately changing the reduction of the horizontal rollers and vertical rollers of the universal rolling mill, H-shaped steels of different specifications can be obtained. The rollers of the universal rolling mill have a simple shape and long service life, and the consumption of the rollers can be greatly reduced. The biggest advantage of rolling H-shaped steel by universal rolling mill is: in the same size series, only the thickness dimensions of the web and flange change, and the dimensions of the other parts are fixed. Therefore, the same series of H-shaped steel rolled with the same universal pass type has a variety of web and flange thickness specifications, which greatly increases the number of H-shaped steel specifications and brings great convenience to users in selecting appropriate sizes and specifications.

In the absence of a universal rolling mill, sometimes in order to meet the urgent needs of production and construction, an ordinary two-roll rolling mill can also be equipped with a vertical roller frame to form a universal pass rolling H-shaped steel. When H-shaped steel is rolled in this way, the dimensional accuracy of the product is low, it is difficult to form a right angle between the flange and the web, the cost is high, and the specifications are small. It is extremely difficult to roll H-shaped steel for columns, so there are not many users.