The dual high-speed wire rod production line of Shaanxi Iron and Steel Group Hanzhong Iron and Steel Co., Ltd. was officially put into operation in August 2012. It is a key project of Hansteel’s product structure adjustment. It designs and produces smooth wire rod coils of Φ 5.5 ~ Φ 16 mm and Φ 6.0 ～ Φ12 mm rebar coils with an annual output of 1 million tons. The main products are general construction coils and general high-quality coils. The main steel types include plain carbon steel, low alloy steel, high-quality carbon steel, welding rod steel, cold heading steel, etc. This production line adopts an elevated platform layout. The rough rolling unit adopts 6 short-stressed rolling mills arranged alternately, and the middle rolling group adopts 8 full-horizontal short-stressed rolling mills. After the rolling line exits the middle rolling group, the high-speed separation line A and Line B. The pre-finishing mill in the high-speed zone adopts 4 cantilever roll ring mills arranged alternately horizontally and vertically, and the finishing mill adopts 10 super-heavy “V” units with top cross 45°. There are a total of 42 rolling mills on the whole line, with a maximum rolling speed of 90 m/s. The process layout is shown in Figure 1.
Main technical parameters
1) Billet elevator. The lifting height is about 3.5 m, the lifting speed is about 0.3 m/s, and the chain spacing is 1500 mm.
2) Heating furnace. It adopts a walking beam type billet heating furnace with double regenerative combustion of blast furnace gas and roller table side inlet and side outlet. Heating blank specifications: 150 mm × 150 mm × 12 000 mm and 160 mm × 160 mm × 12 000 mm. Rated production capacity: 200 t/h (carbon steel, cold charging), billet discharge temperature 1 000 ～ 1 150 ℃, effective length of heating furnace is about 31 m.
3) The main components of the rolling mill. The roughing mill stands alternately with 6 short-stress line rolling mills, 610 /520 × 4 stands and 480 /420 × 2 frame. There are 8 short-stress line rolling mills in full level in the middle rolling mill, 610/520×2 stands, 480/420×4 stands, and 380/330×2 stands. After the middle rolling, it is divided into two lines, each with 4 pre-finishing mills and 10 finishing mills. The pre-finishing mill adopts a “cantilever rolling mill” arranged alternately in horizontal and vertical positions, and the finishing mill adopts a super-heavy “V” type mill with 10 top cross 45°.
4) Air-cooled line. Roller Stelmor standard type and delayed cooling type with “Jia Ling” system, divided into 11 sections, total length 93 m, insulation cover length 75 m, linear speed of air-cooled roller table is 0.1 ～2.0 m / s. There are 12 cooling fans, using centrifugal fans, each with an air volume of 154 000 m3/h and a static pressure of 3 kPa. A drop section is set at the junction of three of the air-cooled roller table sections to change the overlapping position of the coils and minimize the influence of “hot spots”. The roller table in the entrance section can be raised and lowered to optimize the loop-forming pattern of the wire in the production range. Equipped with a heat preservation cover to realize delayed cooling of specific steel grades. In order to improve the air flow distribution and air volume, the “air split” technology and damper adjustment device are adopted to ensure uniform cooling of the coil
5) Vertical core frame collection system. The core frame collects the coils from the collection drum. When a full roll is collected, it is conveyed in the direction of P-F line through the roller bed arranged under the core frame. At the same time, the second core frame is transferred to the collection coil. Below the tube. When the core frame is transferred to the P-F line unwinding position, the core frame is rotated to the horizontal unwinding position through the 90° rotating mechanism. Hang the coil on the P-F line C hook by the coil transport trolley. It is better to use the vertical winding core frame to transport and collect the coil.
6) P- F transportation line. Transport the coils on the rolling trolley to the strapping machine, weighing station, unloading station, etc., which can complete the actions of unwinding, trimming and sampling, bundling, weighing, labeling, unloading, etc., and will The coil is further cooled. The total length is 560 m, 80 hooks, the maximum load-carrying capacity of C-shaped hooks is 2 500 kg, and the running speed is 0.25 m/s.
7) Wire packing machine. SUNDS horizontal type, the maximum pressing force is 400 kN, the maximum roll height after pressing is 2 000 mm, the bundling cycle is 32 s, the bundling material is steel wire, and the bundling is 4 times.
According to product positioning and project site selection, the layout of the workshop adopts the hot charging and hot delivery process, which is closely connected with the continuous casting workshop. The continuous casting billet span and the high-speed wire raw material span are shared. At the same time, the double-high line and the subsequent single-high line are in the public Consider sharing the auxiliary and machine repair facilities, and separate the finished products to ensure the smooth logistics of the two high-speed production lines and the full sharing of public facilities.
1) The roughing mill stands alternately with 6 stands, single-strand rolling. The head-off and separation of steel are realized on the sub-steel roller table, and the two flows enter the full-level 8-stand middle rolling mill. This process arrangement can maximize the number of shared rolling mills. Compared with other four-stand rough rolling mills on double-high lines, the arrangement of a total of 44 rolling mills with 8 intermediate rolling mills, 6 pre-finishing mills, and 10 finishing mills can reduce the number of rolling mills. At the same time, the cross-section of the rolling piece of the dual-stream rolling is smaller and the rolling is more stable. The change brought about is that the middle sub-steel roller table needs to be lengthened by more than ten meters, but in general, this process plan saves investment and makes rolling more stable.
2) Optimized the pass design and roll matching of the intermediate rolling mill. Usually, the distance between the two rolling center lines in the double-strand rolling is unchanged. The rolling center line has been changed in this project to solve the short stress line rolling mill roll body Short, limited by the rolling centerline during double-strand rolling, the number of roll grooves is small, and the rolls are not fully utilized. The utilization rate of the rolling rods in double-strand rolling is improved, and the production cost is reduced.
3) The design considers both 150 mm × 150 mm and 160 mm × 160 mm continuous casting billets.
4) The heating furnace adopts a side-mounted side-discharge walking beam heating furnace, which has the advantages of flexible production operation, uniform billet heating temperature, less oxidation burning loss and energy saving.
5) One water tank is installed after pre-finishing rolling, and three water tanks are installed after finishing rolling. Each water tank has a water pressure of 0.6 MPa, a water volume of 150 m3/h, a backlash water pressure of 1.2 MPa, and a maximum temperature drop of 120 ℃. The rolling piece control cooling system is used to precisely control the temperature of the rolling piece, which can make the temperature of the rolling piece uniform over the entire length, effectively control the temperature entering the finishing mill and the spinning temperature, and improve the uniformity of product quality and mechanical properties.
6) An optical diameter gauge is installed before and after the finishing mill, and the optical diameter gauge is used to continuously detect the size of the wire rod online, so that the finishing mill adjuster can quickly provide feedback information, improve product dimensional accuracy, and reduce out-of-tolerance products.
7) Except for the introduction of the baler, the rest of the equipment is designed and supplied domestically. Using domestic mature and advanced technology, it can effectively reduce the total investment while ensuring product quality.
8) The vertical core frame system is adopted to collect the coils, which is smaller than the traditional double core rod collection, with smaller space requirements, flexible layout and better control of the shape of the coil.
9) The two lines share the P-F line system, with an online tracking system, which can be divided into A line, B line rolling and specification unloading to avoid unloading confusion.
The double-high line of this project is arranged jointly with another single-high line, and the two lines share water treatment facilities, swirling pool, roll room, and raw material span. The workshop consists of one span of raw materials, two spans of raw materials, heating furnace span, double-high wire main rolling span, high-speed wire finished product span and roll room. The raw material span and heating furnace span, main rolling span, finished product span and roll room of the double-high line are arranged in a “T” shape. The total length of the workshop is 531 m, the maximum width is 120 m, the layout is compact, and the total area is small.
1) The raw material span of the double high-speed wire workshop and the billet span of the continuous casting workshop are separated by 8 m, and the medium pipeline route is arranged in the middle. The high-speed wire feedstock is equipped with a turning-steel cooling bed, and the continuous casting billet can be directly sent off the high-speed wire feedstock line or directly heated by the elevator. This arrangement can make full use of the storage capacity of the continuous casting billet span and raw material span to meet the turnover and storage of 1.6 million t/a billets.
2) A 5 m elevated platform on the entire line, pipelines and bridges such as hydraulic stations are arranged under the platform, and forklift channels are arranged under the platform to facilitate the transportation of the flying shear head material frame.
3) The crane rail elevation of the main rolling span of the high-speed line is + 14. 5 m. Because the heating furnace is arranged in the main rolling span, the rail elevation must be controlled at a certain height, otherwise the heating furnace roof and the crane cab will easily interfere.
4) There are 42 rolling mills on the whole line, except for the middle rolling mills, all of them are arranged horizontally and implement single-line non-twist rolling. The rough and intermediate rolling mills adopt a new generation of short-stress line rolling mills.
5) The main rolling span of the double-high line rolling mill has a span of 30 m. The double-line area has a large operating side space, which can meet the requirements of simultaneous operation and maintenance of the two lines. Spare parts are placed in the middle. The pipelines and forklift channels under the platform are more convenient. The P-F layout is also More compact.
The A line of the Shaanxi Iron and Steel Group’s Hanshan Iron and Steel double high-speed wire rod production line was successfully tested under the heat load on August 6, 2012, and the line B was successfully tested under the heat load on September 5, 2012. The production line has advanced technology and equipment, reasonable engineering design, smooth production, and has reserved space for further development, such as high-pressure water descaling devices for tapped billets. The double-high-line production line has high output and low one-time investment, and has certain competitive advantages in the field of low-end wire production.
This article comes from Shaanxi Iron and Steel Group Hanzhong Iron and Steel Co., Ltd. translated by LMM,