Rebar is the surface ribbed bar, also known as ribbed bar, usually with two longitudinal ribs and transverse ribs evenly distributed along the length direction. The shape of transverse rib is spiral, herringbone and crescent. Expressed in millimeters of nominal diameter. The nominal diameter of ribbed bar is equal to the nominal diameter of plain round bar with equal cross section. The nominal diameter of reinforcement is 8-50mm, and the recommended diameter is 8, 12, 16, 20, 25, 32, 40mm. The ribbed steel bar mainly bears tensile stress in concrete. Because of the action of the rib, the reinforced bar with rib has a great bond ability with the concrete, so it can bear the action of the external force better. Ribbed steel bars are widely used in various building structures, especially large, heavy, light thin-walled and high-rise buildings.

The screw steel is produced by small rolling mill. The main types of small rolling mill are continuous, semi continuous and horizontal. In the world, most of the new and in use small continuous mills are used. The popular steel rolling mill has general high-speed steel rolling mill and 4-section high-yield steel rolling mill.

The billets used for continuous small rolling mill are generally continuous casting billets with side length of 130-160mm, length of 6-12M and single weight of 1.5t-3t. Most of the rolling lines are arranged in the alternative of flat and interchange, so as to realize the whole line of rolling without torsion. There are 18, 20, 22 and 24 small rolling mills according to different billet specifications and finished product sizes, 18 of which are the mainstream. In bar rolling, many new processes such as step heating furnace, high pressure water descaling, low temperature rolling and endless rolling are adopted. Rough rolling and medium rolling are developed to adapt to large billets and improve rolling accuracy. Finishing mill mainly improves precision and speed (up to 18m / s). The product specification is generally ф 10-40mm, and there are also ф 6-32mm or ф 12-50mm. The steel produced is low, medium and high carbon steel and low alloy steel which are widely needed in the market; the maximum rolling speed is 18m / s. The production process is as follows:

Step heating furnace → roughing mill → medium rolling mill → finishing mill → water cooling device → cold bed → cold shear → automatic counting device → bundling machine → unloading bench theoretical weight calculation formula of screw steel provided by Shanghai Jiuzheng environmental protection building materials Co., Ltd.: outer diameter Х outer diameter Х 0.006117 = kg / M specification weight manufacturer 6.50.260 Jiuzheng steel 8.00.395 Jiuzheng steel 100.617 Jiuzheng steel 120.888jiuzheng steel 141.21 Jiuzheng steel Zhenggang steel 161.58 Jiuzheng steel 182.00 Jiuzheng steel 202.47 Jiuzheng steel 222.98 Jiuzheng steel 253.85 Jiuzheng steel 284.83 Jiuzheng steel 326.31 Jiuzheng steel.