Method for improving production efficiency of low-temperature steel bars

Abstract

The invention discloses a method for improving the production efficiency of low-temperature steel bars, which specifically comprises the step of cooling rolled pieces before the rolled pieces enter a finishing mill group in a specific manner that a group of two-section water-through cooling water pipes and a water seal device are mounted behind an outlet of a twelfth rolling mill and are used for cooling the rolled pieces discharged from the twelfth rolling mill; after passing through a 2 # flying shear head, entering a thirteenth rolling machine, and controlling the finish rolling temperature between 910 DEG C and 950 DEG C; on the basis of ensuring the normal-temperature and low-temperature performance of a low-temperature steel bar product, the temperature waiting time before rolling is shortened, the production efficiency is improved, and the machining cost of the low-temperature steel bar is reduced.

Description

Technical Field

[0001] The invention relates to a method for improving the production efficiency of low-temperature steel bars. Background Art

[0002] Low-temperature steel bars are a special type of steel used in reinforced concrete structures of LNG outer tanks and accident collection tanks at the bottom of liquefied natural gas storage tanks. They require not only high room temperature performance, but also high strength and plasticity at ultra-low temperatures of -165°C. This requires that multiple elements and a high alloy content must be added to the steel. To ensure the solid solution effect of the alloy elements, a higher heating temperature is inevitably required. However, in order to improve the effect of fine grain strengthening, a lower final rolling temperature must be used. To reduce the final rolling temperature, the only way is to wait for the temperature before rolling, reduce the start rolling temperature, and then reduce the final rolling temperature. Since the temperature before rolling needs to be kept for about 2.5 minutes, and the pure rolling time of a billet is about 80 seconds, the temperature before rolling seriously affects the rolling rhythm, and the production efficiency is very low. The processing cost of the rolling process is more than twice the processing cost of ordinary rebar. In order to improve the production efficiency of low-temperature steel bars and reduce processing costs, it is necessary to reduce the temperature waiting time before rolling on the basis of ensuring the final rolling temperature. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for improving the production efficiency of low-temperature steel bars in view of the shortcomings of the above-mentioned prior art, thereby shortening the waiting time before rolling, improving production efficiency and reducing the processing cost of low-temperature steel bars on the basis of ensuring the normal temperature and low temperature performance of low-temperature steel bar products.

[0004] The technical solution of the present invention to solve the above technical problems is a method for improving the production efficiency of low-temperature steel bars, which is specifically: The rolled piece is cooled before entering the finishing mill. The specific method is as follows: A set of two-stage water-penetrating cooling water pipes and water seal devices are installed close to the exit of the 12th rolling mill to cool the temperature of the rolled pieces coming out of the 12th rolling mill. After passing through the 2# flying shear head, they enter the 13th rolling mill to control the final rolling temperature between 910℃ and 950℃.

[0005] The present invention further defines the scheme: Preferably, the water pressure of the first section of the water-penetrating cooling water pipe is controlled at 13kg-18kg, and the water pressure of the second section of the water-penetrating cooling water pipe is controlled at 10kg-15Kg.

[0006] Preferably, the water-penetrating cooling water pipe is 1.5-3m long.

[0007] Preferably, a collecting tank is installed under the water-penetrating cooling device to collect waste water, which is recycled into the production circulating water system through a dark ditch and recycled after purification.

[0008] Preferably, a pyrometer is installed in front of the 13th rolling mill to monitor the temperature of the rolled pieces entering the 13th rolling mill in real time, and the final rolling temperature is controlled between 910°C and 950°C.

[0009] The beneficial effects of the present invention are as follows: the present invention installs a pyrometer in front of the 13th rolling mill to monitor the temperature of the rolled piece entering the 13th rolling mill, controls the final rolling temperature between 910°C and 950°C, reduces the temperature fluctuation of the pass rod of the rolled piece, ensures the uniform performance of the finished pass rod of the low-temperature steel bar, not only achieves the fine grain strengthening effect, but also ensures the low-temperature steel bar product at room temperature and low temperature performance, shortens the waiting time before rolling, improves production efficiency, and reduces the processing cost of the low-temperature steel bar. DETAILED DESCRIPTION Example

[0010] This embodiment provides a method for improving the production efficiency of low-temperature steel bars, which is used to produce HRB500DW low-temperature steel bars with a specification of Φ16-Φ28 mm. The method is specifically as follows: The rolled piece is cooled before entering the finishing mill. The specific method is as follows: A set of two-section 1.5m water-penetrating cooling water pipes and water seal devices are installed close to the outlet of the 12th rolling mill to cool the temperature of the rolled pieces coming out of the 12th rolling mill. The water pressure of the first section of water-penetrating cooling water is controlled at 13g, and the water pressure of the second section of water-penetrating cooling water is controlled at 10kgKg. A collection tank is installed under the water-penetrating cooling device, and the collected waste water is recycled into the production circulating water system through a dark ditch and recycled after purification; and enters the 13th rolling mill after passing through the 2# flying shear head. A pyrometer is installed in front of the 13th rolling mill to monitor the temperature of the rolled pieces entering the 13th rolling mill in real time and control the final rolling temperature between 910℃-950℃.

[0011] The waiting time and shift production of each specification before and after the use of the present invention are shown in Table 1

[0012] The structure and performance of HRB500DW low-temperature steel bars produced by cooling the rolled pieces before entering the finishing mill are basically consistent with those produced by conventional pre-rolling warming, and the elongation is improved compared with before. At the same time, the production efficiency is greatly improved, and the cost is effectively reduced.

[0013] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A method for improving the production efficiency of low-temperature steel bars, characterized in that: The method is as follows: The rolled piece is cooled before entering the finishing mill. The specific method is as follows: A set of two-stage water-penetrating cooling water pipes and water seal devices are installed close to the exit of the 12th rolling mill to cool the temperature of the rolled pieces coming out of the 12th rolling mill. After passing through the 2# flying shear head, they enter the 13th rolling mill to control the final rolling temperature between 910℃ and 950℃.

2. A method for improving the production efficiency of low-temperature steel bars according to claim 1, characterized in that: The water pressure of the first section of the water-penetrating cooling water pipe is controlled at 13kg-18kg, and the water pressure of the second section of the water-penetrating cooling water pipe is controlled at 10kg-15Kg.

3. A method for improving the production efficiency of low-temperature steel bars according to claim 1, characterized in that: The length of the water-penetrating cooling water pipe is 1.5-3m.

4. The method for improving the production efficiency of low-temperature steel bars according to claim 1, characterized in that: A collecting tank is installed under the water-penetrating cooling device to collect waste water, which is recycled into the production circulating water system through a dark ditch and recycled after purification.

5. The method for improving the production efficiency of low-temperature steel bars according to claim 1, characterized in that: A pyrometer is installed in front of the 13th rolling mill to monitor the temperature of the rolled pieces entering the 13th rolling mill in real time and control the final rolling temperature between 910°C and 950°C.

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