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H-beam production method

2019-06-18

  H-section steel is an economical section and high-efficiency profile with a more optimized cross-sectional area allocation and a more reasonable strength-to-weight ratio. It is named because its section is the same as the English letter "H". Because all parts of the H-beam are arranged at right angles, the H-beam has the advantages of strong bending resistance, simple construction, cost saving and light weight in all directions, and has been widely used.


An economic cross-section profile similar to the uppercase Latin letter H in cross-sectional shape, also known as a universal steel beam, wide-edge (edge) I-beam or parallel flange I-beam. The cross section of the H-shaped steel usually includes two parts of a web plate and a flange plate, also known as a waist and an edge.


The inside and outside of the flange of H-beam are parallel or nearly parallel, and the ends of the flange are at right angles, so they are named parallel flange I-beams. The thickness of the H-shaped steel web is smaller than that of ordinary I-beams with the same web height, and the flange width is larger than that of ordinary I-beams with the same web thickness, so it is also known as wide-edge I-beam. Determined by the shape, the section modulus, moment of inertia and corresponding strength of the H-shaped steel are obviously better than those of ordinary I-beams with the same single weight. Used in metal structures with different requirements, whether it is subjected to bending moments, pressure loads, or eccentric loads, it shows its superior performance, which can greatly improve the carrying capacity compared to ordinary I-beams, saving 10% to 40% of the metal. H-shaped steel has wide flanges, thin webs, multiple specifications and flexible use. It can save 15% to 20% of metal in various truss structures. Because the inside and outside of the flange are parallel and the edges are at right angles, it is easy to assemble and combine into various components, which can save about 25% of the welding and riveting workload, which can greatly speed up the construction of the project and shorten the construction period.


Due to the above advantages, H-beams are widely used, mainly for: various civil and industrial building structures; various large-span industrial plants and modern high-rise buildings, especially industrial plants in areas with frequent seismic activity and high temperature working conditions; Large bridges with large bearing capacity, good cross-section stability, and large spans; heavy equipment; highways; ship skeletons; mine support; foundation treatment and dyke engineering; various machine components.


There are many product specifications of H-beam, 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-beam. The flange width B of the wide flange and the middle flange H-shaped steel is greater than or equal to the web height H. The flange width B of the narrow flange H-shaped steel is approximately equal to one half of the web height H. (2) Divided into H-shaped steel beams, H-shaped steel columns, H-shaped steel piles, and extremely thick flange H-shaped steel beams according to product use. Sometimes parallel leg channel steel and parallel flange T-shaped steel are also included in the scope of H-beam. Generally, narrow flange H-shaped steel is used as the beam material, and wide flange H-shaped steel is used as the column material. According to this, it is also known as beam-shaped H-shaped steel and column-shaped H-shaped steel. (3) According to the production method, it is divided into welded H-beam and rolled H-beam. (4) Divided into large, medium and small H-shaped steel according to the size. Products with a web height H of 700mm or more are usually called large, those with 300-700mm are called medium, and those with less than 300mm are called small. By the end of 1990, the world's largest H-shaped steel web had a height of 1200 mm and a flange width of 530 mm.




  Internationally, the product standards of H-beams are divided into two categories: inch systems and metric systems. The United States, the United Kingdom and other countries use the British system, China, Japan, Germany and Russia and other countries use the metric system. Although the British and metric systems use different units of measurement, most of the H-beams use 4 sizes to indicate their specifications, namely: web height h, flange width b, web thickness d, and flange thickness t. Although the world ’s H-beam size specifications are expressed differently. However, the size and range of the products produced are not much different.


H beam can be produced by welding or rolling. Welding H-shaped steel is to cut the strip with the appropriate thickness to the appropriate width, and weld the flange and the web together on a continuous welding unit. Welding H-shaped steel has the disadvantages of large metal consumption, difficult to ensure uniform product performance, and limited size and specifications. Therefore, H-beams are mainly produced by rolling. In modern steel rolling production, universal rolling mills are used to roll H-beams. The web of the H-shaped steel is rolled between the upper and lower horizontal rolls, and the flange is simultaneously rolled into the shape between the side of the horizontal roll and the vertical roll. Since the universal edge rolling mill cannot be used to press down the flange edge, it is necessary to install a universal edge mill behind the universal stand, commonly known as the edge mill, in order to reduce the flange edge and control the width of the flange. . In the actual rolling operation, the two stands are used as a group to make the rolled product pass back and forth several times (Figure 2a), or to pass the rolled product through several universal stands and one or two edged end stands. The continuous rolling mill is composed of a certain amount of rolling per pass, and the billet is rolled into a product with the required shape and size. At the flange part of the rolling part, due to the sliding between the side surface of the horizontal roll and the rolling part, the wear of the rolling part is relatively large. In order to ensure that the rolls after the heavy load can return to their original shape, the sides of the upper and lower horizontal rolls of the roughing unit and the corresponding vertical roll surfaces should be inclined at an angle of 3 ° to 8 °. In order to correct the inclination of the flange of the finished product, a finished universal rolling mill, also called a universal finishing rolling mill, is set up, whose side of the horizontal roll is perpendicular to the axis of the horizontal roll or has a small inclination angle, generally not more than 20 ′, and the vertical roll is cylindrical.


Using a universal rolling mill to roll H-shaped steel, the cross section of the rolled piece can be more uniformly extended, and the speed difference between the roll surface on the inside and outside of the flange is small, which can reduce the internal stress of the product and defects on the shape. By appropriately changing the reduction amount of the horizontal and vertical rolls of the universal rolling mill, H-section steels of different specifications can be obtained. The shape of the roll of the universal rolling mill is simple, the life is long, and the consumption of the roll can be greatly reduced. The biggest advantage of the universal rolling mill for rolling H-beams is that only the thickness of the web and flanges of the same size series are changed, and the dimensions of the other parts are fixed. Therefore, the same series of H-beams rolled with the same universal profile have multiple web and flange thickness thickness specifications, which greatly increases the number of H-beam specifications and brings great convenience for users to choose the appropriate size.


无 In the case of no universal rolling mill, in order to meet the urgent needs of production and construction, ordinary two-roll mills can also be equipped with vertical roll frames to form universal hole-shaped rolled H-beams. Rolling H-shaped steel in this way has low dimensional accuracy, difficult to form a right angle between the flange and the web, high cost, few specifications, and it is extremely difficult to roll H-shaped steel for column material, so there are not many users.


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