A method for improving the bending degree of steel bars for mining chains
By improving the bending degree of mining chain steel bars through processes such as low-temperature rolling and cooling bed insulation cover, the problem of excessive bending during the production process was solved, achieving efficient production and cost savings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING IRON & STEEL CO LTD
- Filing Date
- 2024-05-21
- Publication Date
- 2026-07-31
AI Technical Summary
Mining chain steel is prone to bending problems during production, which can cause it to get stuck in the annealing furnace during the annealing process, increasing the risk of furnace shutdown and raising production costs.
The bending degree of chain steel bars is improved by adopting methods such as low-temperature rolling, controlling the entry and sizing temperature, and using a heat preservation cover on the cooling bed, and by configuring the heating furnace online, high-pressure water descaling, alternating horizontal and vertical short stress line rolling mills, and controlled cooling.
It effectively improves the curvature of chain steel bars, avoids furnace jamming during annealing, eliminates the straightening process, reduces production costs and speeds up delivery. The straightness of chain steel within 0.3% reaches over 99.00%.
Smart Images
Figure BDA0004849660930000022
Abstract
Description
Technical Field
[0001] This invention relates to the field of steel production, and more particularly to a method for improving the curvature of steel bars used in mining chains. Background Technology
[0002] Mining chain steel, used in coal mining machinery, is in high demand. This type of steel has high requirements for hardenability, mechanical properties, surface quality, and straightness. Chain steel has a high content of alloys such as Cr, Mo, and Mn, making it prone to bending during the segmentation process after production. Due to the high surface hardness of the rolled material, it needs to be annealed before straightening and flaw detection for customer use. Because of its high degree of bending, the round steel can easily get stuck in the annealing furnace during annealing, causing furnace shutdowns and risks of mixed furnace numbers.
[0003] Therefore, it is necessary to develop new methods to improve the bending degree of steel bars for mining chains. Summary of the Invention
[0004] Objective of the Invention: To address the shortcomings and defects of existing technologies, this invention provides a method for improving the bending degree of mining chain steel bars. This method utilizes low-temperature initial rolling combined with controlled rolling and cooling to improve the diameter. Problems with the bending of steel bars used in mining chains.
[0005] Technical Solution: The present invention provides a method for improving the bending degree of steel bars for mining chains, characterized in that: a blank of 250mm×300mm×10500mm is used for production. Round steel bars are produced using an online heating furnace, high-pressure water descaling system, 22 alternating horizontal and vertical short stress line rolling mills, 4 three-roll KOCKS rolling mills, 5 flying shears, and 7 online controlled cooling water tanks. The cooling bed is equipped with an insulation cover. By using low-temperature rolling, controlling the entry and sizing temperature, and using an insulation cover on the cooling bed, the bending degree of mining chain steel bars is improved.
[0006] The heating furnace ensures uniform heating of the billet during the heating process, with individual thermocouple temperature fluctuations ≤20℃.
[0007] The low-temperature initial rolling process involves controlling the initial rolling temperature at 1000℃-1090℃, the sizing temperature at 900℃-950℃, and the rolling without water penetration. The initial rolling mill speed is reduced to 0.4m / s for the four stands.
[0008] The rolling temperature for the low-temperature rolling process is controlled at 1060℃.
[0009] During the rolling mill operation, water tanks #3 and #4 are used and the booster pumps are turned off. The pressure in water tanks #3 and #4 is maintained at 7.5 Bar. All water tanks #5, #6, and #7 are taken offline.
[0010] The cooling bed is equipped with an insulation cover, and the length of the upper cooling bed is set between 86m and 94m. The cooling bed moves with one tooth at a time, and the movement of the cooling bed is controlled to be once every 15 seconds, so that the rolled material is slowly cooled on the cooling bed.
[0011] The billet comprises the following components in the indicated mass percentages: C: 0.21%-0.24%, Mn: 1.24%-1.40%, Si: 0.1%-0.2%, Ni: 0.95%-1.06%, Mo: 0.52%-0.65%, Cr: 0.50%-0.65%, Cu: ≤0.15%, P+S+Al<0.48%, and Fe balance.
[0012] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: By optimizing the process and employing methods such as low-temperature initial rolling, controlling the entry and sizing temperature, and using an insulation cover on the cooling bed, this invention can effectively improve the curvature of the chain steel, avoid the problem of steel getting stuck in the annealing furnace during the annealing process, eliminate the straightening process, reduce production costs, and accelerate delivery speed. Testing shows that the proportion of chain steel with a straightness within 0.3% is over 99.00%. This process can save straightening costs of 225 yuan / ton, meet customer requirements, and shorten delivery time. Detailed Implementation
[0013] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0014] This invention relates to a method for improving the bending degree of steel bars used in mining chains, using a blank of 250mm×300mm×10500mm for production. Round steel bars are produced using an online heating furnace, high-pressure water descaling system, 22 alternating horizontal and vertical short stress line rolling mills, 4 three-roll KOCKS rolling mills, 5 flying shears, and 7 online controlled cooling water tanks. The cooling bed is equipped with an insulation cover. By using low-temperature rolling, controlling the entry and sizing temperature, and using an insulation cover on the cooling bed, the bending degree of mining chain steel bars is improved.
[0015] The heating temperature is optimized so that the billet is heated evenly during the heating process, and the temperature fluctuation of a single thermocouple is ≤20℃.
[0016] Heating process:
[0017]
[0018] The initial rolling temperature is controlled at 1000℃-1090℃, with a target of 1060℃. The sizing temperature is 900℃-950℃. No water is applied after rolling. The initial rolling mill speed is reduced to 0.4m / s for the first four stands.
[0019] During rolling, water tanks #3 and #4 are used and the booster pumps are turned off. The pressure in water tanks #3 and #4 is maintained at 7.5 Bar. Water tanks #5, #6, and #7 are all taken offline.
[0020] The cooling bed is equipped with an insulation cover. The length of the upper cooling bed is set between 86m and 94m. The cooling bed operates on a 1-tooth-1-movement basis, with the movement controlled to occur once every 15 seconds. The rolled material is slowly cooled on the cooling bed. In the production scheduling plan, cold-sheared steel is prioritized before high-temperature gear steel and should not be scheduled together with bearing steel, free-cutting steel, or other high-temperature steels that require cooling.
[0021] The billet comprises the following components in the following mass percentages: C: 0.21%-0.24%, Mn: 1.24%-1.40%, Si: 0.1%-0.2%, Ni: 0.95%-1.06%, Mo: 0.52%-0.65%, Cr: 0.50%-0.65%, Cu: ≤0.15%, P+S+Al<0.48%, Fe balance.
[0022] Testing showed that over 99.00% of the chain steel had a straightness within 0.3%. This process can save 225 yuan / ton in straightening costs, meet customer requirements, and shorten delivery time.
Claims
1. A method for improving the bending degree of steel bars for mining chains, characterized in that: Using 250mm×300mm×10500mm billets, φ16mm-60mm round steel is produced. The system includes an online heating furnace, high-pressure water descaling, 22 alternating horizontal and vertical short-stress line rolling mills, 4 three-roll KOCKS mills, 5 flying shears, and 7 online controlled cooling water tanks. An insulation cover is installed above the cooling bed. The bending degree of mining chain steel bars is improved through low-temperature initial rolling, controlled entry and sizing temperatures, and the use of an insulation cover on the cooling bed. The heating furnace ensures uniform heating of the billet, with individual thermocouple temperature fluctuations ≤20℃. The low-temperature initial rolling temperature is controlled at 1060℃, and the entry and sizing temperatures are 900℃-950℃. No water piercing is performed after rolling, and the initial rolling speed of the four stands is reduced to 0.4m / s. During rolling, the mills... Use water tanks #3 and #4 with the booster pumps shut off. Maintain the pressure in water tanks #3 and #4 at 7.5 Bar. All water tanks #5, #6, and #7 are off the production line. The cooling bed is covered with an insulation cover. The length of the upper cooling bed is set between 86m and 94m. The cooling bed operates with one tooth moving at a time, controlled to move once every 15 seconds. The rolled material is slowly cooled on the cooling bed. The billet comprises the following components by mass percentage: C: 0.21%-0.24%, Mn: 1.24%-1.40%, Si: 0.1%-0.2%, Ni: 0.95%-1.06%, Mo: 0.52%-0.65%, Cr: 0.50%-0.65%, Cu: ≤0.15%, P+S+Al < 0.48%, Fe balance.