The reducing and sizing mill is installed between the finishing mill and pinch roll/laying head. Through this arrangement, the large water tank for rapid cooling of the rolled piece can be realized, the temperature of rolled piece entering the reducing and sizing mill can be controlled, and the internal structure of the wire rod can be improved by using the hot rolling process, and the mechanical properties and surface quality of products can be improved.
In the design, a double stand reducing mill and a double stand sizing mill are independently added after the finishing mill, and the reducing sizing mill shares part of the extension, which greatly reduces the rolling speed of the 8 stands finishing mill, correspondingly reduces the sharp temperature rise caused by wire deformation in the high-speed area, controls the temperature of the rolled piece, realizes the low-temperature and high-speed temperature control rolling, and ensures the mechanical properties of the product.
In the pass design of the whole production line, the traditional oval round pass system with large commonality is adopted. Due to the large reduction rate of the reducing mill, the cross-section of the rolled piece can be adjusted flexibly, thus greatly simplifying the pass system of roughing, intermediate rolling, pre-finishing and finishing mill groups, which reduces the spare parts storage of the roll and rod ring, simplifies the roll management and reduces the cost The number of roll changing is reduced and the operation rate of rolling mill is improved.
After the finished product of the reducing and sizing machine, the dimensional accuracy of the final product is high. The guaranteed value of dimensional tolerance is generally ± 0.1 mm, and the ovality is 60% of the total dimensional deviation.
The reducing and sizing mill is mainly composed of four cantilevered rolling mill stands with V-shape layout. The first two are reducing mills and the second two are sizing mills. The elliptical round hole type system is adopted to obtain products with high dimensional accuracy.
The reducing and sizing unit is composed of two 230mm reducing mills and two 150mm sizing mills driven by an AC motor through a set of the combined gearbox. The combined gearbox is equipped with 9 clutches. When rolling products of different specifications, changing the position of 9 clutches can combine the speed ratios meeting different requirements. By setting a reasonable roll gap, the micro tension rolling in the reducing and sizing mill can be ensured, so as to obtain products with high dimensional accuracy. The maximum rolling force of the reducing mill is 330kn, the maximum rolling force of the sizing mill is 130kN, the maximum design speed is 140m/s, and the guaranteed rolling speed is 112m/s.
In order to meet the requirements of high-speed rolling, the sizing machine adopts a compact design. The center distance between the two sizing machines is only 150 mm. A small triangle static guide is installed between the two sizing machines, which can not only reduce the risk of steel piling, but also avoid the stop of the machine due to the damage of the guide roller bearing caused by the use of the rolling guide. In order to ensure the rolling speed, the sizing machine is equipped with a roll axis axial adjustment mechanism and hydraulic balance device, which can adjust the rolling line online.
Wire rod rolling specification：φ5.5-φ16mm
Rolling speed：110m/s
Allowed rolling force: reducing dia. 330KN, sizing dia. 130KN
Roller Shaft dia: reducing dia 230mm, sizing dia. 150mm
Rolling temperature: ≥750℃
