Multifunctional bar graded temperature control rolling and controlled cooling equipment

Abstract

The invention provides multifunctional bar graded temperature control rolling and controlled cooling equipment, and belongs to the technical field of hot-rolled bar on-line controlled rolling and cooling equipment. The equipment comprises four cooling sections of the 1# A cooling section which is arranged on an outlet of a 12# rolling mill, the B cooling section which is arranged between a 14# rolling mill and a 18# rolling mill, the 2# C cooling section which is arranged behind the 18# rolling mill, and the 3# D cooling section which is arranged behind 3# double length shears. The multifunctional bar graded temperature control rolling and controlled cooling equipment has the advantages that the specifications of suitable products range from 10 mm to 60 mm in diameter; the yield strength grade of suitable steel ranges from 400 MPa to 1100 MPa; the ultimate temperature after controlled rolling can achieve 800 DEG C; the cooling area ranges from 300 DEG C to 1000 DEG C; the cooling speed adjustable range is 30-500 DEG C / s; the temperature fluctuation of a finish rolling inlet after controlled rolling and cooling and an upper cooling bed is smaller than or equal to + / -7.5 DEG C. The multifunctional bar graded temperature control rolling and controlled cooling equipment has obvious advantages on generality, cooling evenness, the controlled rolling and ultra fast cooling mode, the cooling area, the cooling speed adjustable range and the like, and the cooling demand for various steel kinds, full specifications and precise evenness of bar products is met for the first time.

Description

technical field [0001] The invention belongs to the technical field of on-line controlled rolling and controlled cooling equipment for hot-rolled bars, and in particular provides a multifunctional step-by-step temperature-controlled rolling and controlled cooling equipment for bars. Background technique [0002] At present, there are serious deficiencies in the controlled rolling and cooling or ultra-fast cooling equipment developed and promoted by Danieli and some domestic scientific research institutions, mainly reflected in the controlled rolling mode, the limit temperature of controlled rolling, and the ultra-fast cooling after rolling. There are problems in the mode, cooling temperature range, adjustable range of cooling speed, and temperature fluctuation after cooling. As a result, this type of equipment has poor versatility after it goes online, and cannot meet the needs of multi-steel types and multi-standard differentiated cooling processes. The specific problems are...

AI Technical Summary

Problems solved by technology

[0002] At present, there are serious deficiencies in the controlled rolling and cooling or ultra-fast cooling equipment developed and promoted by Danieli and some domestic scientific research institutions, mainly reflected in the controlled rolling mode, the limit temperature of controlled rolling, and the ultra-fast cooling after rolling. There are problems in the mode, cooling temperature range, adjustable range of cooling speed, and temperature fluctuation after cooling. As a result, this type of equipment has poor versatility after it goes online, and cannot meet the needs of multi-steel types and multi-standard differentiated cooling processes. The specific problems are as follows:

[0003] 1) Low-temperature rolling at 780-800°C has significant advantages, such as refining austenite grains, increasing deformation dislocation density, inhibiting recrystallization and reducing mixed crystals, refining pearlite lamellar spacing, and delaying bainite / marine However, at present, most bar production lines have very small cooling temperature drop capacity within a limited distance between machines, which cannot meet the temperature control requirements;

[0004] 2) It cannot meet the requirements of large-scale cooling immediately after low-temperature rolling deformation on the rack, and the effect of low-temperature rolling will be weakened, such as the rapid disappearance of high-density low-temperature deformation dislocations, rapid coarsening of austenite grains after low-temperature deformation, etc.

[0005] 3) The cross-section temperature difference in the cooling process between rolling mills is large, especially for large-scale cross-sections (surface, 1 / 4, and core), the temperature difference between the core and the surface can reach more than 200°C, resulting in "yin and yang surfaces" in the rolling intermediate billet, and steel stacking accidents high rate;

[0006] 4) One-stage cooling is mostly used, and the controllable range of the bar starting cooling and final cooling temperature range is small, especially the final cooling temperature is difficult to control accurately, and the steel types and specifications suitable for cooling cover a small range

[0007] 5) The uniformity of cooling after rolling is poor, black lines appear on some surfaces, and the surface quality is poor; the difference in structure is large, and the local residual stress is large, which leads to severe bending of the cooling bed strip especially on small specifications (≤Φ14mm), and cannot be rolled forward

[0008] 6) The structural type of the overall cooler is single, and the cooling speed can be adjusted in a small range during different temperature drop stages during the cooling process;

[0009] 7) The automation level is low, and the online closed-loop control of the flow rate based on the constant target temperature has not been realized, resulting in large fluctuations in the inlet temperature of the finished rolling after cooling and the temperature of the upper cooling bed (reaching ±15°C and ±20°C respectively)

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