Production method of H-beam

H-section steel is a kind of economic section high-efficiency profile with more optimized section area distribution and more reasonable strength weight ratio. It is named because its section is the same as the English letter "H". Due to the right angle arrangement of all parts of H-beam, H-beam has the advantages of strong bending resistance, simple construction, cost saving and light structure weight in all directions, which has been widely used.

The section shape is similar to an economic section profile of capital Latin letter H, which is also called universal steel beam, wide edge (side) I-beam or parallel flange I-beam. The cross section of H-beam usually consists of web and flange plate, also known as waist and edge.

The inner and outer sides of the flange of H-beam are parallel or close to parallel, and the flange ends are at right angles, so it is named parallel flange I-beam. The web thickness of H-beam is smaller than that of common I-beam with the same height of web, and the flange width is larger than that of common I-beam with the same height of web, so it is also called wide edge I-beam. Determined by the shape, the section modulus, the moment of inertia and the corresponding strength of H-beam are obviously superior to the common I-beam of the same single weight. It can be used in metal structures with different requirements, whether it bears bending moment, pressure load or eccentric load, which shows its superior performance. Compared with ordinary I-beam, it can greatly improve the bearing capacity and save 10% - 40% of metal. H-section steel has wide flange, thin web, many specifications and flexible use. It can save 15% - 20% metal in various truss structures. Because the inner and outer sides of the flange are parallel and the flange ends are at right angles, it is convenient to assemble and assemble various components, thus saving about 25% of the welding and riveting work, greatly speeding up the construction speed of the project and shortening the construction period.

Due to the above advantages, H-beam is widely used, mainly for: various civil and industrial building structures; various large-span industrial plants and modern high-rise buildings, especially in areas with frequent seismic activities and under high temperature working conditions; large bridges with large bearing capacity, good section stability and large span; heavy equipment; expressways; ship framework; Mine support; foundation treatment and dike engineering; various machine components.

There are many specifications of H-beam products, and the classification methods are as follows. (1) According to the flange width of the product, it is divided into wide flange, middle flange and narrow flange H-shaped steel. The flange width b of wide flange and middle flange H section steel is greater than or equal to the web height H. The flange width b of the narrow flange H section steel is about half of the web height H. (2) According to the purpose of the product, it can be divided into H-shaped steel beam, H-shaped steel column, H-shaped steel pile and H-shaped steel beam with extremely thick flange. Sometimes parallel leg channel steel and parallel flange T-beam are also included in the scope of H-beam. Generally, H-shaped steel with narrow flange is used as beam material, and H-shaped steel with wide flange is used as column material. (3) According to the production mode, it can be divided into welding H-beam and rolling H-beam. (4) According to the size and specification, it is divided into large, medium and small H-shaped steel. Generally, products with web height h above 700mm are called large size, 300-700mm are called medium size, and products with web height less than 300mm are called small size. By the end of 1990, the world's largest H-beam web had a height of 1200mm and a flange width of 530mm.

Internationally, H-beam product standards are divided into British system and metric system. The United States, the United Kingdom and other countries use the British system, while China, Japan, Germany and Russia use the metric system. Although the measurement units used in the British system and the metric system are different, most of the H-shaped steels use four dimensions to express their specifications, namely: web height h, flange width b, web thickness D and flange thickness t. Although different countries in the world express the size of H-beam in different ways. However, there is little difference between the size range and tolerance of the products.

H-beam can be produced by welding or rolling. Welding H-section steel is to cut the strip with appropriate thickness into appropriate width, and weld the flange and web together in the continuous welding unit. Welding H-beam has many disadvantages, such as large metal consumption, not easy to ensure uniform product performance and limited size. Therefore, H-beam is mainly produced by rolling. In modern rolling production, universal mill is used to roll H-beam. The web of H-beam is rolled between the upper and lower horizontal rolls, while the flange is rolled between the horizontal roll side and vertical roll at the same time. Because only universal rolling mill can not press the flange edge end, so it is necessary to set the edge rolling end machine behind the universal stand, commonly known as edge rolling machine, so as to press the flange edge end and control the flange width. In the actual rolling operation, the two stands are taken as a group to make the rolled piece pass repeatedly for several times (Fig. 2a), or to make the rolled piece pass through a continuous rolling mill composed of several universal stands and one or two edge rolling end stands, each pass is applied with a certain amount of reduction, and the blank is rolled into the product of the required specification, shape and size. In the flange part of the rolled piece, because of the sliding between the side of the horizontal roll and the rolled piece, the wear of the roll is relatively large. In order to ensure that the roll can be restored to its original shape after heavy rolling, the side of the upper and lower horizontal rolls and the corresponding vertical roll surface of the roughing mill should be inclined at an angle of 3 ° - 8 °. In order to correct the inclination angle of the finished product flange, the finished product universal rolling mill, also known as universal finishing mill, is set. Its horizontal roll side is perpendicular to the horizontal roll axis or has a smaller inclination angle, generally no more than 20 ', and the vertical roll is cylindrical

When H-beam is rolled by universal rolling mill, the cross section of the rolled piece can be extended more evenly, the speed difference between the inner and outer roll surfaces of the flange is smaller, and the internal stress and the defects on the shape of the product can be reduced. Different specifications of H-beam can be obtained by changing the reduction of horizontal roll and vertical roll of universal mill.