H-beam can be produced by welding or rolling.
Welding H-section steel is to cut the strip steel with appropriate thickness into appropriate width, and weld the flange and web together in the continuous welding unit. Welding H-section steel has the disadvantages of large metal consumption, difficult to ensure uniform product performance, limited size and specification and so on. Therefore, H-beam is mainly produced by rolling method. In modern steel rolling production, universal mill is used to roll H-beam. The web of H-beam is rolled between the upper and lower horizontal rolls, and the flange is rolled between the side of the horizontal roll and the vertical roll at the same time. Because the universal rolling mill alone cannot press down the flange edge, it is necessary to set up the edge rolling machine behind the universal frame, commonly known as the edge rolling machine, in order to press down the flange edge and control the flange width. In the actual rolling operation, take the two stands as a group to make the rolled pieces pass back and forth several times (Fig. 2a), or make the rolled pieces pass through the continuous rolling unit composed of several universal stands and one or two rolling edge end stands, and apply a certain reduction for each pass to roll the blank into the product with the required specification, shape and size. Due to the large flange on the side of the roll, there is wear between the roll and the rolled piece. In order to ensure that the roll after heavy turning can return to the original shape, the side of the upper and lower horizontal rolls of the roughing mill and the corresponding vertical roll surface should be inclined at an angle of 3 ° ~ 8 °. In order to correct the inclination of the finished flange, the finished universal mill, also known as the universal finishing mill, is set. The side of the horizontal roll is perpendicular to the axis of the horizontal roll or has a small inclination angle, which is generally no more than 20 ', and the vertical roll is cylindrical.
By rolling H-beam with universal rolling mill, the section of rolled piece can be extended evenly, and the speed difference between the inner and outer roll surfaces of flange is small, which can reduce the internal stress and appearance defects of products. By properly changing the reduction of horizontal roll and vertical roll of universal mill, H-beam of different specifications can be obtained. The roll of universal rolling mill has the advantages of simple shape and long service life, and the consumption of roll can be greatly reduced. The advantage of universal mill rolling H-beam is that in the same size series, only the thickness of web and flange is changed, and the dimensions of other parts are fixed. Therefore, the same series of H-section steel rolled by the same universal pass has a variety of web and flange thickness specifications, which greatly increases the number of H-section steel specifications and brings great convenience for users to select appropriate sizes.
When there is no universal mill, sometimes in order to meet the urgent needs of production and construction, the ordinary two high mill can also be added with vertical roll frame to form a universal pass to roll H-beam. Rolling H-section steel in this way has low dimensional accuracy, it is difficult to form a right angle between flange and web, high cost and few specifications. It is very difficult to roll H-section steel for column, so there are few users.