A device, system and method for improving the strength of threaded steel and the density of surface oxide layer

Abstract

The present invention belongs to the technical field of threaded steel in iron and steel metallurgy, and particularly relates to a device, system and method for improving the strength of threaded steel and the density of the surface oxide layer. The device includes: a post-rolling light water penetration mechanism, which is used to perform preliminary light water penetration cooling on the rolled steel bars; a vertical lifting mechanism, which is used to accommodate and sequentially lift the steel bars that have passed through the post-rolling light water penetration mechanism layer by layer; and an aerosol cooling mechanism, in which an aerosol cooling mechanism is correspondingly arranged on each layer of the vertical lifting mechanism, and is used to perform aerosol cooling on each layer of steel bars that pass through the vertical lifting mechanism. The present invention solves the problem of insufficient reaction between flat-laid steel bars (the distribution method of steel bars in existing cooling beds) and water vapor and the problem of cheap acquisition of water vapor, that is, water vapor is obtained cheaply, and the physical phenomenon that water vapor rises when heated is utilized to make water vapor and steel bars fully react.

Description

Technical Field

[0001] The present invention belongs to the technical field of threaded steel in iron and steel metallurgy, and in particular relates to a device, a system and a method for improving the strength of threaded steel and the compactness of a surface oxide layer. Background Art

[0002] Residual heat treated steel bars are hot rolled steel bars that have been penetrated with water. The hot rolled steel bars are cooled by penetrating water. In a short time, the surface temperature of the steel bars is cooled from 900℃ to about 600℃. After penetrating with water, the core of the steel bar transfers heat to the surface of the steel bar. After the surface temperature returns to about 800℃, it is cooled on a cooling bed. This can improve the strength of the steel bar and reduce the amount of alloy added. However, the surface of the residual heat treated steel bar is more prone to rust than the surface of ordinary hot rolled steel bars. The reason can be explained as follows: the final rolling temperature of ordinary hot rolled steel bars is generally above 900℃. Since they are not penetrated with water, the surface of the steel is oxidized to form a relatively thick iron oxide scale. The surface layer is mainly ferroferric oxide. The iron oxide scale may partially fall off during the cooling and collection process, but it is generally not destroyed in large quantities. Since ferroferric oxide is very stable in the air at room temperature, this layer of iron oxide scale is wrapped on the surface of the steel bar to protect the steel bar matrix from corrosion. Therefore, the surface of ordinary hot rolled steel bars is not easy to rust. After the final rolling, the residual heat treated steel bars need to be quickly cooled by water. The surface temperature of the steel bars after water penetration is generally 600℃. In a short period of time, the surface temperature of the steel bars cools down from 900℃. Due to the effect of thermal expansion and contraction, the iron oxide scale on the surface of the steel bars is no longer tightly bonded to the steel bar matrix, and the iron oxide scale becomes relatively loose. At the same time, due to the high water pressure during water penetration, generally not less than 1.0MPa, the iron oxide scale falls off under the impact of water. After water penetration and cooling, the surface temperature of the steel bars rises to a certain extent after self-tempering, which can reach up to about 800℃, and a certain thickness of ferroferric oxide protective layer is generated. However, the ferroferric oxide protective layer generated on the surface of the residual heat treated steel bars in the later stage is not as dense as that of the hot-rolled steel bars, resulting in poor surface corrosion resistance.

[0003] At an appropriate temperature, the steel bars react with water vapor for a period of time. Since the oxidizing property of water vapor is slightly worse than that of oxygen, the reaction product is mainly Fe3O4, not Fe2O3. A layer of dark black oxide (3Fe+4H2O=Fe3O4+4H2) will form on the surface of the steel parts. Its main component is Fe3O4, and the mass proportion of oxygen in water vapor (oxygen mass proportion in water vapor is 94%) is much higher than the mass proportion of oxygen in air (oxygen volume proportion in air is 21%), which is conducive to the generation of a large amount of Fe3O4. Therefore, the generated oxide layer is relatively dense, has certain wear resistance and is not easy to fall off. However, the cheap acquisition of water vapor in the prior art has always been a difficult problem to solve. Patent CN 201210457049 discloses a straightening plate and a straightening method for steel production, wherein the straightening plate comprises a first part and a second part formed on the first part, wherein the second part comprises a plurality of grids formed at a certain distance on the upper surface of the first part, a plurality of teeth are arranged on the top of the grid, and a notch for placing the steel is formed between adjacent teeth of the same grid, and a surface treatment medium storage tank is also formed on the straightening plate, and the surface treatment medium storage tank is surrounded by two adjacent grids and the upper surface of the first part, and the surface treatment medium stored in the surface treatment medium storage tank absorbs the heat emitted when the steel is cooled, and reaches the surface of the steel after evaporation, changes the surface structure of the steel and forms a dense anti-rust layer on the surface of the steel. On the basis of providing a straightening effect, the invention can play a role in modifying the oxide scale on the surface of the rolled piece, so as to achieve the purpose of rust prevention and improving the surface quality of the rolled piece, thereby simplifying the process, reducing the process and reducing the cost. However, since the hot steel bars are not in direct contact with the cooling water in the storage tank, the heat transferred from the hot steel bars to the cooling water in the storage tank is limited, and the amount of water vapor generated is small, which is not enough to generate a Fe3O4 oxide layer of sufficient thickness. Summary of the invention

[0004] In view of the above problems, the present invention provides a device, system and method for improving the strength of threaded steel and the density of the surface oxide layer. The device comprises:

[0005] The post-rolling light water penetration mechanism is used to perform preliminary light water penetration cooling on the rolled steel bars. The surface temperature of the steel bars after they leave the water tank is 800-850℃, and the surface temperature of the steel bars after they return to temperature is 900-950℃.

[0006] A vertical lifting mechanism is used to accommodate and lift the steel bars that have passed through the rolled light water-penetrating mechanism layer by layer;

[0007] An aerosol cooling mechanism is provided on each layer of the vertical lifting mechanism, and is used for performing aerosol cooling on each layer of steel bars passing through the vertical lifting mechanism.

[0008] Preferably, the vertical lifting mechanism comprises a plurality of lifting assemblies arranged at intervals in the horizontal direction, the lifting assemblies being located between the steel unloading side and the cooling bed; the lifting assemblies are equipped with gravity sensing assemblies;

[0009] The device also includes a power mechanism for driving a plurality of lifting components to operate in a synchronous length and synchronous frequency manner.

[0010] Preferably, the length of each layer of the aerosol cooling mechanism is the same as the length of the cooling bed, and each layer of the aerosol cooling mechanism comprises a plurality of cooling nozzles, and the aerosol nozzles are aimed at each layer of steel bars in the lifting device.

[0011] The present invention provides a system for improving the strength of threaded steel and the compactness of the surface oxide layer, comprising: a cooling control module for controlling a post-rolling light water penetration mechanism, a vertical lifting mechanism and an aerosol cooling mechanism;

[0012] The cooling control module includes a temperature measuring unit, a flow meter, a pressure gauge, a pneumatic regulating valve and a cooling water volume calculation module;

[0013] The temperature measurement module includes measuring the temperature of the steel bar surface entering the vertical lifting mechanism and measuring the temperature of the steel bar surface at the end of the aerosol cooling;

[0014] The cooling water volume calculation unit calculates the cooling water spray volume according to the target steel bar surface temperature setting value at the end of aerosol cooling, the actual detection value of the steel bar surface temperature entering the vertical steel bar lifting device, the actual detection value of the steel bar surface temperature at the end of aerosol cooling, and the production process parameters.

[0015] The present invention provides a method for improving the strength of threaded steel and the density of the surface oxide layer, comprising the following steps:

[0016] After rolling, the steel bars are lightly water-penetrated and cooled by a post-rolling light water-penetration mechanism, and then the steel bars are lifted layer by layer by a vertical lifting mechanism. Each layer of steel bars passing through the vertical lifting mechanism is cooled by an aerosol cooling mechanism. After the steel bars are lifted to the last layer of the vertical lifting mechanism, they enter the cooling bed for cooling.

[0017] Specifically, the present invention adopts the following technical scheme: after rolling, the steel bars are lightly penetrated with water for cooling, and then the steel bars facing the upper cooling bed are aerosol cooled and water vapor is generated. During the rising process of the water vapor, an oxidation reaction occurs with the surface of other steel bars to form an Fe3O4 oxide layer. The present invention comprises a light water penetration mechanism after rolling, an aerosol cooling mechanism for cooling the steel bars, and a mechanism for vertically lifting the steel bars.

[0018] Light water penetration mechanism after rolling: There are two groups of water penetration tanks, the first group is 6-7m long, and the second group is 5-6m long. The total flow rate of cooling water in the control tank is: 300-500m 3 / h water pressure is: 0.6~1.0MPa, the running speed of steel bars in the water tank is 3~14m / s, the amount of steel passing per hour is: 100~150 tons, the surface temperature of the steel bars before entering the water tank is 950~1050℃, the surface temperature of the steel bars after passing through the water tank is 800~850℃, and the surface temperature of the steel bars after returning to temperature is 900~950℃.

[0019] Vertical lifting mechanism: The vertical lifting mechanism includes several lifting components arranged at intervals in the horizontal direction, and the lifting components are composed of a driving gear, a driven gear, a chain, and a steel support rod. The driving gear is located directly above the driven gear, and the distance between the center point of the driving gear and the center point of the driven gear is 1.2-2m. The diameter of the top circle of the driving gear is 30-40cm, and the tooth spacing is 5-10cm. The driving gear and the driven gear are the same in size and shape. The steel support rod is a rod-shaped object, the length of the steel support rod is 10-20cm, and the spacing between the steel support rods is 10-20cm. The steel support rods are fixed on the chain and evenly distributed along the length direction of the chain. The straight line where the steel support rods are located is parallel to the plane where the driving gear is located. The angle between the steel support rod and the chain is 30-60°. The chain is connected to the driving gear and the driven gear in a circular manner. The chain can drive the steel support rod to rotate along the two gears as the gears rotate.

[0020] Arrange 20-40 lifting assemblies in a straight line next to the cooling bed. The 20-40 lifting assemblies constitute a vertical lifting mechanism, which is located between the steel unloading side and the cooling bed. After light water penetration, the steel bars can be directly unloaded from the steel unloading device to the steel bar support rods of the lifting assemblies after being cut into sections with multiple lengths. Several lifting assemblies of the vertical steel bar lifting mechanism run according to the step length, and the walking step length is the same as the spacing between the steel bar support rods. The 20-40 lifting assemblies run in a synchronous length and synchronous frequency mode. When used for the first time, adjust the 20-40 lifting assemblies. The components are arranged such that a steel bar support rod in each lifting component is located at a position where the steel bars unloaded from the steel unloading side can be received. A gravity sensing device is installed in the lifting component. Whenever the steel unloading side unloads the steel bars into the vertical lifting mechanism, the vertically lifted steel bars sense the increase in gravity. The 20-40 lifting components move upward one step at the same time, and then the steel bar lifting device pauses. After the pause, a steel bar support rod in each lifting component is still located at a position where the steel bars unloaded from the steel unloading side can be received. After the next steel bar is unloaded, the lifting component moves upward one step again, and the cycle repeats. The 20-40 lifting components can jointly lift the steel bars after the fixed length from the bottom to the top by 1.2-2m, and the steel bars on one side of the lifting component are distributed in rows from bottom to top. After the steel bars are lifted to the highest point, they slide into the step-type cooling bed through the slide rails under the action of gravity along the other side of the lifting component to cool. Then the step-type cooling bed cools and moves the steel bars using the existing technology.

[0021] Aerosol cooling mechanism for cooling steel bars: Since there are steel bars distributed in rows from bottom to top on the steel bar support rods on the steel unloading side of the vertical lifting mechanism, the aerosol cooling mechanism for cooling the steel bars is a device for spraying aerosol to cool the steel bars distributed in rows. There are four layers in total, which cool the four bottom layers of steel bars of the vertical lifting mechanism respectively. The length of each layer of aerosol cooling mechanism is the same as the length of the cooling bed. Each layer of aerosol cooling mechanism has an aerosol nozzle cooling line. The spraying directions of the four layers of cooling nozzles are distributed in the direction of 35-50 degrees to the upper right, 35-50 degrees to the upper left, 35-50 degrees to the lower right, and 35-50 degrees to the lower left. The cooling nozzles are aimed at each layer of steel bars in the vertical lifting mechanism.

[0022] Cooling control module: The cooling control module consists of a temperature measuring unit, a flow meter, a pressure gauge, a pneumatic regulating valve and a cooling water volume calculation unit. The temperature measuring unit measures the temperature of the steel bar surface entering the vertical lifting mechanism and the steel bar surface at the end of the mist cooling. The cooling water volume calculation unit calculates the cooling water spray volume according to the target temperature setting value of the steel bar surface at the end of the mist cooling, the actual detection value of the steel bar surface temperature entering the vertical lifting steel bar device, the actual detection value of the steel bar surface temperature at the end of the mist cooling and the production process parameters. The water flow is specifically controlled by the flow meter, pressure gauge and pneumatic regulating valve. The specific calculation method and cooling process are as follows:

[0023] (1) The model calculates the cooling water spraying amount based on the target surface temperature setting value of the steel bar at the end of the mist cooling, the actual detection value of the steel bar surface temperature entering the vertical lifting mechanism, and the rolling process parameters. The calculation formula is:

[0024] (A) The amount of water spray required to cool a unit length of steel bar to the target temperature is proportional to the weight of the steel bar and the temperature drop produced by spray cooling.

[0025] V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 -T 散 ) ①

[0026] (B) The amount of heat dissipated into the air by natural heat dissipation from a unit length of steel bar is proportional to the surface area of ​​the steel bar, the heat dissipation time, the steel bar temperature, and the heat dissipation coefficient of the steel.

[0027] Q 散 = K2*N* t*2*3.14*r(T 目标 +T 进 ) / 2 ②

[0028] (C) The amount of heat dissipated into the air by natural heat dissipation from a unit length of steel bar is proportional to the weight of the steel bar, its specific heat capacity, and the temperature drop of heat dissipation.

[0029] Q 散 = K3*N*7.85*3.14*r 2 *T 散 ③

[0030] (D) Combine equations ①, ②, and ③ to eliminate Q 散 、T 散 have to:

[0031] V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 - K2* t(T 目标 +T 进 ) / ( K3 *7.85*r)) ④

[0032] (E) When the mist cooling is completed, the temperature of the steel bar surface is detected and the corrected proportionality coefficient is calculated using the following formula ⑤.

[0033] K 修正 = V / (N*7.85*3.14*r 2 *(T 进 -T 出 - K2* t(T 出 +T 进 ) / ( K3 *7.85*r)) ) ⑤

[0034] (F) Total water supply for mist cooling: V 总 =V*L ⑥

[0035] In formulas ① to ⑥, V is the amount of water sprayed per decimeter of steel bar to cool to the target temperature, (L / dm); K1 is the proportionality coefficient, (L / (kg·℃)), which is 0.002 in the present invention; N is the number of steel bars on the single-layer steel bar support rod; r is the radius of the steel bar, (dm); T 目标 is the target temperature setting value of the steel bar surface at the end of mist cooling, (℃); T 进 is the actual detected value of the steel bar surface temperature entering the vertical lifting mechanism, (℃); T 出 is the actual measured value of the steel bar surface temperature at the end of mist cooling, (℃); T 散 It is the temperature drop value caused by the steel bar entering the vertical lifting mechanism to the end of the mist cooling by natural heat dissipation to the air, (℃); Q 散 is the heat dissipated into the air by natural heat dissipation of the steel bar per decimeter (W); K2 is the heat dissipation coefficient of the steel bar (W / dm 2·℃), which is taken as 0.39 in the present invention; t is the time from the steel bar entering the vertical lifting mechanism to the end of the mist cooling stage, (s); K3 is the specific heat capacity of steel (J / (kg·℃), which is taken as 460 in the present invention; V 总 is the amount of water sprayed required to cool the steel bars in the vertical lifting mechanism to the target temperature, (L); L is the length of the vertical lifting steel bar device, (dm);

[0036] K 修正 is the corrected proportionality coefficient (L / (kg·℃)), if K 修正 If the offset between K1 and K2 exceeds 10%, the corrected proportionality factor K 修正 Instead of K1, the cooling water spray volume of the next steel bar entering the vertical lifting mechanism is calculated by formula ④, and the real-time temperature of the steel bar surface at the end of subsequent aerosol cooling is continuously measured, and whether K1 needs to be corrected is calculated according to formula ⑤.

[0037] (2) Cooling process:

[0038] The four-layer aerosol cooling device is vertically distributed from bottom to top, the first layer cooling nozzle, the second layer cooling nozzle, the third layer cooling nozzle, the fourth layer cooling nozzle, the water pressure of the cooling nozzle is: 0.2 ~ 0.3Mpa, the air pressure is: 0.3 ~ 0.4Mpa, the gas flow rate is 10-15Nm 3 / ton of steel, the total water flow range of the first layer cooling nozzle is set to: 4 ~ 14L / s. The total water flow range of the second layer cooling nozzle is set to: 0 ~ 12L / s, preferably 1 ~ 12L / s. The total water flow range of the third layer cooling nozzle is set to: 0 ~ 10L / s, preferably 1 ~ 10L / s. The total water flow range of the fourth layer cooling nozzle is set to: 0 ~ 8L / s, preferably 1 ~ 8L / s.

[0039] The distance between the aerosol cooling nozzle and the steel bar is 90-100 mm, the spray angle of the cooling nozzle in the length direction of the steel bar is 90-110°, and the spacing between the aerosol cooling nozzle in the length direction of the steel bar is 160-200 mm.

[0040] The number of layers of cooling nozzles to be opened is determined according to the total amount of cooling water required. The priority order of opening the cooling nozzles is: first-layer cooling nozzles > second-layer cooling nozzles > third-layer cooling nozzles > fourth-layer cooling nozzles, so that the sum of the cooling water injection amounts of each layer is equal to the calculated value of the cooling water injection amount.

[0041] The number of steel bars facing the unloading side of the vertical lifting mechanism is 10-12 layers. The steel bar temperature at the fourth layer is controlled to be 600-700℃. The average cooling rate of the steel bars in the aerosol cooling section in the vertical lifting mechanism is controlled to be:

[0042] 3.5-12℃ / s, the mist cooling section has an accelerated cooling effect on the steel bar, which is beneficial to grain refinement under this temperature range and cooling rate, but will not generate bainite phase. The generated water vapor can also react with the steel bar surface in the lifting device to generate a dense Fe3O4 layer.

[0043] 3Fe+4H2O=Fe3O4+4H2

[0044] A water tank is arranged at the bottom of the vertical lifting mechanism to collect the aerosol cooling water dripping downward after cooling the steel bars. The water in the water tank flows into the water circulation device and is used again for aerosol cooling of the steel bars after being filtered.

[0045] Compared with the prior art, the advantages of the present invention are:

[0046] 1. The present invention performs three-stage cooling on the rebar after finish rolling, namely light water cooling, mist cooling and air cooling, and the cooling rate gradually decreases from high temperature to low temperature. First, the cooling intensity of water cooling is reduced, which is beneficial to avoid the appearance of overcooling organization and reduce the occurrence of oxide layer shedding on the surface of steel bars; in the mist cooling section, the steel bars are cooled at a medium cooling rate, and the surface temperature of the steel bars in the mist cooling section is controlled to be higher than 600°C. Since the steel bars do not undergo bainite transformation above 580 degrees, cooling the steel bars at a medium cooling rate in the mist cooling section can not only improve the strength of the steel bars but also avoid the generation of unqualified organizations such as bainite (the national standard requires that there should be no bainite rings). The mist cooling section can also produce cheap water vapor, which can generate a dense ferroferric oxide layer after reacting with the surface of the steel bars. The mist cooling is also beneficial to the improvement of cooling uniformity; the steel bars are conventionally air-cooled below 600°C, which is the formation temperature of ferrite + pearlite organization. Ferrite + pearlite is the most desired organization for hot-rolled steel bars. Conventional air cooling of the steel bars below 600°C is conducive to the formation of ferrite + pearlite organization.

[0047] 2. The present invention designs a steel bar vertical lifting mechanism, which can make multiple horizontal steel bars distributed and move in sequence from bottom to top, and can also perform aerosol cooling on the steel bars in the vertical lifting mechanism. The water vapor generated by the aerosol when it meets the high-temperature steel bars reacts with the vertically distributed steel bars during the rising process to form a dense Fe3O4 layer, which solves the problem of insufficient reaction between flat-laid steel bars (the distribution method of steel bars in the existing cooling bed) and water vapor and the problem of cheap acquisition of water vapor, that is, water vapor is obtained cheaply, and the physical phenomenon that water vapor rises when heated is utilized, so that water vapor and steel bars react fully.

[0048] 3. The present invention provides a calculation model for the amount of water used for aerosol cooling, which can accurately calculate the amount of cooling water used for steel bars of different specifications according to the target surface temperature and the detection temperature of the steel bars, which is beneficial to the precise control of the structure and strength of the steel bars. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of the vertical lifting mechanism provided by the present invention;

[0050] Figure 2 It is a schematic diagram of the cooling process of the steel bar in the vertical lifting mechanism;

[0051] Figure 3 It is a schematic diagram of the cooling nozzle direction in a four-layer aerosol cooling device;

[0052] Figure 4a The corrosion resistance of the steel bars produced in Example 1, Comparative Example 1 and Comparative Example 2 after being exposed outdoors for 12 days is compared; Figure 4b The corrosion resistance of the steel bars produced in Example 1, Comparative Example 1 and Comparative Example 2 after being exposed outdoors for 25 days is compared; Figure 4c The corrosion resistance of the steel bars produced in Example 1, Comparative Example 1 and Comparative Example 2 after being exposed outdoors for 60 days is compared; Figure 4a , 4b , the steel bars in 4c are, from left to right, respectively: the steel bars produced in Example 1, the water-piercing steel bars produced in Comparative Example 1, the water-piercing steel bars produced in Comparative Example 1, the hot-rolled steel bars produced in Comparative Example 2, the hot-rolled steel bars produced in Comparative Example 2, and the steel bars produced in Example 1;

[0053] Reference numerals:

[0054] 1. Driving gear; 2. Driven gear; 3. Chain; 4. Steel bar support rod; 5. Steel bar; 6. First layer cooling nozzle; 7. Second layer cooling nozzle; 8. Third layer cooling nozzle; 9. Fourth layer cooling nozzle; 10. Gas pressure gauge; 11. Gas flow meter; 12. First pneumatic valve; 13. Gas source; 14. Cooling water pressure gauge; 15. Cooling water flow meter; 16. Second pneumatic valve; 17. Water source; 18. Steel bar surface temperature detection position in vertical lifting mechanism; 19. Steel bar surface temperature detection position at the end of aerosol cooling; 20. Third pneumatic valve; 21. Fourth pneumatic valve; 22. Fifth pneumatic valve; 23. Sixth pneumatic valve. DETAILED DESCRIPTION

[0055] The following instructions are attached Figure 1 -4 A method for improving the strength of threaded steel and the density of the surface oxide layer provided by the present invention is further described in the form of a specific embodiment.

[0056] Embodiment 1:

[0057] A steel plant produces rebar with the grade HRB400E, and the steel composition is: C: 0.23%, Si: 0.30%, Mn: 1.40%, V: 0.016%, N: 98ppm.

[0058] A method for improving the strength of threaded steel and the density of the surface oxide layer provided by the present invention is used to cool the steel bars. Specifically, the steel bars are lightly penetrated with water for cooling after rolling, and then the steel bars adjacent to the upper cooling bed are aerosol cooled to generate water vapor. During the rising process of the water vapor, an oxidation reaction occurs with the surfaces of other steel bars to generate an Fe3O4 oxide layer. The method comprises a light water penetration mechanism after rolling, an aerosol cooling mechanism for cooling the steel bars, and a vertical lifting mechanism.

[0059] Light water-penetrating mechanism after rolling: There are two groups of water-penetrating water tanks, the first group is 6.5m long and the second group is 5.5m long. The diameter of the finished steel bar after rolling is Φ20mm. The double-cut rolling process is adopted. The total flow rate of cooling water in the water tank after rolling is: 400~450m 3 / h water pressure is 0.9MPa, the speed of steel bars in the water tank is 13.5m / s, the amount of steel passing per hour is: 120-130 tons, the surface temperature of the steel bars before entering the water tank is 970-1030℃, the surface temperature of the steel bars after leaving the water tank is 800-850℃, and the surface temperature of the steel bars after returning to temperature is 900-950℃.

[0060] As the present invention Figure 1 As shown, the vertical lifting mechanism includes a plurality of lifting components arranged at intervals in the horizontal direction, and the lifting component consists of a driving gear 1, a driven gear 2, a chain 3, and a steel support rod 4. The driving gear 1 is located directly above the driven gear 2, and the distance between the center point of the driving gear 1 and the center point of the driven gear 2 is 1.5-2m. The diameter of the tooth top circle of the driving gear 1 is 31.05cm, and the tooth spacing is 7.5cm. The driving gear 1 and the driven gear 2 are the same in size and shape. The steel support rod 4 is a rod-shaped object, the length of the steel support rod 4 is 15cm, and the spacing between the steel support rods 4 is 15cm. The steel support rods 4 are fixed on the chain 3 and are evenly distributed along the length direction of the chain 3. The straight line where the steel support rods 4 are located is parallel to the plane where the driving gear 1 is located. The angle between the steel support rods 4 and the chain 3 is 45°. The chain 3 connects the driving gear 1 and the driven gear 2 in a circumferential manner, and the chain 3 can drive the steel support rods 4 to rotate along the two gears during the rotation of the gears.

[0061] 30 lifting assemblies are arranged in a straight line close to the cooling bed, and the vertical lifting mechanism is located between the steel unloading side and the cooling bed. The steel bars after light water penetration can be directly unloaded from the steel unloading device to the steel bar support rods of the vertical lifting mechanism after being cut into sections with multiple lengths. The lifting assemblies operate according to the step length, and the walking step length is the same as the spacing between the steel bar support rods 4. The 30 lifting assemblies operate in a synchronous length and synchronous frequency manner. When used for the first time, the 30 lifting assemblies are adjusted so that a steel bar support rod 4 in each lifting assembly is located at a position that can receive the steel bar 5 unloaded from the steel unloading side. A gravity sensing device is installed in the lifting assembly. Whenever the steel unloading side unloads the steel bar 5 into the vertical lifting mechanism, the vertically lifted steel bar senses the increase in gravity, and the 30 lifting assemblies move upward one step at the same time, and then the movement of the lifting assemblies is paused. After the pause, a steel bar support rod 4 in each lifting assembly is still located at a position that can receive the steel bar 5 unloaded from the steel unloading side. After the next steel bar 5 is unloaded, the lifting assembly is lifted upward one step again, and this cycle is repeated. The 30 lifting assemblies can jointly lift the sized steel bars 5 from the bottom to the top by 1.6m, and make the steel bars 5 on one side of the lifting assemblies distributed in rows from bottom to top. After the steel bars 5 are lifted to the highest point, they slide into the walking cooling bed through the slide rails along the other side of the lifting assemblies under the action of gravity for cooling, and then the walking cooling bed cools and moves the steel bars 5 using existing technology.

[0062] The cooling process of the steel bar 5 in the vertical lifting mechanism is shown in the attached figure. Figure 2 As shown, since there are steel bars 5 arranged in rows from bottom to top on the steel bar support rod 4 on the steel bar unloading side of the vertical lifting mechanism, the aerosol cooling mechanism for the steel bars 5 is a mechanism for spraying aerosol to cool the steel bars 5 arranged in rows from bottom to top, and there are four layers in total, which cool the four layers of steel bars at the bottom of the vertical lifting mechanism respectively. The length of each layer of the aerosol cooling mechanism is the same as the length of the cooling bed, and each layer of the aerosol cooling device has an aerosol nozzle cooling line. The spraying directions of the four layers of cooling nozzles are distributed as shown in the attached figure of the present invention. Figure 3 As shown, the cooling nozzles are aimed at each layer of steel bars in the lifting device at 45 degrees to the upper right, 45 degrees to the upper left, 45 degrees to the lower right, and 45 degrees to the lower left.

[0063] Cooling control module: The cooling control module is composed of a temperature measuring unit, a flow meter, a pressure gauge, a pneumatic regulating valve and a cooling water volume calculation unit. The temperature measuring unit detects the temperature of the steel bar surface at the steel bar surface temperature detection position 18 of the vertical lifting mechanism and the steel bar surface temperature detection position 19 at the end of the mist cooling. The cooling water volume calculation unit calculates the cooling water spraying volume according to the steel bar surface target temperature setting value at the end of the mist cooling, the steel bar surface temperature actual detection value at the vertical lifting mechanism, the steel bar surface temperature actual detection value at the end of the mist cooling and the production process parameters. The water flow out of the water source 17 is specifically controlled by the cooling water flow meter 15, the cooling water pressure gauge 14, the second pneumatic valve 16, the third pneumatic valve 20, the fourth pneumatic valve 21, the fifth pneumatic valve 22 and the sixth pneumatic valve 23. The specific calculation method and cooling process are as follows:

[0064] (A) The amount of water spray required to cool the steel bar per unit length to the target temperature is proportional to the weight of the steel bar and the temperature drop caused by spray cooling:

[0065] V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 -T 散 ) ①

[0066] (B) The amount of heat dissipated into the air by natural heat dissipation from a unit length of steel bar is proportional to the surface area of ​​the steel bar, the heat dissipation time, the steel bar temperature, and the heat dissipation coefficient of the steel.

[0067] Q 散 = K2*N* t*2*3.14*r(T 目标 +T 进 ) / 2 ②

[0068] (C) The amount of heat dissipated into the air by natural heat dissipation from a unit length of steel bar is proportional to the weight of the steel bar, its specific heat capacity, and the temperature drop of heat dissipation.

[0069] Q 散 = K3*N*7.85*3.14*r 2 *T 散 ③

[0070] (D) Combine equations ①, ②, and ③ to eliminate Q 散 、T 散 have to:

[0071] V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 - K2* t(T 目标 +T 进) / ( K3 *7.85*r)) ④

[0072] (E) When the mist cooling is completed, the temperature of the steel bar surface is detected and the corrected proportionality coefficient is calculated using the following formula ⑤.

[0073] K 修正 = V / (N*7.85*3.14*r 2 *(T 进 -T 出 - K2* t(T 出 +T 进 ) / ( K3 *7.85*r)) ) ⑤

[0074] (F) Total water supply for mist cooling: V 总 =V*L ⑥

[0075] In formulas ① to ⑥, V is the amount of water sprayed per decimeter of steel bar to cool to the target temperature, (L / dm); K1 is the proportional coefficient (L / (kg·℃)), which is 0.002 in the present invention; N is the number of steel bars on the single-layer steel bar support rod; r is the radius of the steel bar, (dm); T 目标 is the target temperature setting value of the steel bar surface at the end of mist cooling, (℃); T 进 is the actual detected value of the steel bar surface temperature entering the vertical lifting mechanism, (℃); T 出 is the actual measured value of the steel bar surface temperature at the end of mist cooling, (℃); T 散 It is the temperature drop value caused by the steel bar entering the vertical lifting mechanism to the end of the mist cooling by natural heat dissipation to the air, (℃); Q 散 is the heat dissipated into the air by natural heat dissipation of the steel bar per decimeter (W); K2 is the heat dissipation coefficient of the steel bar (W / dm 2 ·℃), the value in this patent is 0.39; t is the time from the steel bar entering the vertical lifting mechanism to the end of the mist cooling stage, (s); K3 is the specific heat capacity of steel (J / (kg·℃), the value in this patent is 460; V 总 is the amount of water sprayed required to cool the steel bars in the vertical lifting mechanism to the target temperature, (L); L is the length of the vertical lifting mechanism, (dm);

[0076] K 修正 is the corrected proportionality coefficient (L / (kg·℃)), if K 修正 If the offset between K1 and K2 exceeds 10%, the corrected proportionality factor K 修正 Instead of K1, the cooling water spray volume of the next steel bar entering the vertical lifting mechanism is calculated by formula ④, and the real-time temperature of the steel bar surface at the end of subsequent aerosol cooling is continuously measured, and whether K1 needs to be corrected is calculated according to formula ⑤.

[0077] The parameters in this example are K1 = 0.002 L / kg·°C, N = 2, r = 0.1 dm, T 进 =930℃、T 目标 =630℃、K2=0.78W / dm 2 ·℃, t=31.12s, K3=460J / (kg·℃), total length of cooling bed 1200dm, put into formula ④, ⑥ to get:

[0078] V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 - K2* t(T 目标 +T 进 ) / ( K3 *7.85*r)) ④

[0079] =0.002*2*7.85*3.14*(0.1) 2 *(930-630-0.39*31.12*(630+930) / (460*7.85*0.1))

[0080] =0.244L / dm

[0081] V 总 =V*L ⑥

[0082] =0.244*1200

[0083] =293L

[0084] The actual detection value of the steel bar surface temperature at the end of the mist cooling T 出 The temperature is 600°C, and the parameters in this embodiment are N = 2, r = 0.1dm, T 进 =930℃、T 出 =600℃、K2=0.39W / dm 2 ·℃, t=31.12s, K3=460J / (kg·℃) and put them into formula ⑤ to get:

[0085] K 修正 =V / (N*7.85*3.14*r 2 *(T 进 -T 出 -K2*t(T 出 +T 进 ) / (K3*7.85*r)))

[0086] =0.244 / (2*7.85*3.14*0.1*0.1*(930-600-0.39*31.12*(930+600) / (460*7.85*0.1)))

[0087] =0.00178

[0088] 100%*(K 修正- K1) / K1=11%

[0089] K 修正 If the offset between K1 and K2 exceeds 10%, the corrected proportionality factor K 修正 Instead of K1, take K1=0.00178 to calculate the cooling water spray volume of the next steel bar entering the vertical lifting device.

[0090] (2) Cooling process:

[0091] The cooling process of the steel bar in the vertical lifting mechanism is shown in the attached figure. Figure 2 As shown, the four-layer aerosol cooling mechanism vertically distributed from bottom to top is, in order, the first layer cooling nozzle 6, the second layer cooling nozzle 7, the third layer cooling nozzle 8, and the fourth layer cooling nozzle 9. The compressed air flowing out of the air source 13 is specifically controlled by the gas flow meter 11 and the first pneumatic valve 12. The pressure value of the control gas pressure gauge 10 is: 0.33Mpa, and the gas flow rate is 10-15Nm 3 / ton of steel, the pressure value of the cooling water pressure gauge 14 of the cooling nozzle is: 0.25Mpa, and the total water flow range of the first layer cooling nozzle 6 is set to: 4~14L / s. The total water flow of the second layer cooling nozzle 7 is set to: 1~12L / s. The total water flow of the third layer cooling nozzle 8 is set to: 1~10L / s. The total water flow of the fourth layer cooling nozzle 9 is set to: 0~8L / s. The distance between the mist cooling nozzle and the steel bar is 95mm, the spray angle of the cooling nozzle in the length direction of the steel bar is 100°, and the spacing of the mist cooling nozzle in the length direction of the steel bar is 180mm.

[0092] The number of layers of cooling nozzles to be opened is determined according to the total amount of cooling water required. The priority order of opening the cooling nozzles is: first layer cooling nozzle 6 > second layer cooling nozzle 7 > third layer cooling nozzle 8 > fourth layer cooling nozzle 9, so that the sum of the cooling water injection amount of each layer is equal to the calculated value of the cooling water injection amount.

[0093] According to the production process parameters, the running speed of the steel bar after final rolling is 13.5m / s, and the length of the steel bar after being cut into sections by multiple lengths is 105m. It is calculated that a section of steel bar is sent into the vertical lifting mechanism every 7.78 seconds (105÷13.5=7.78), and the vertical lifting mechanism also moves upward one step. The cooling time of the steel bar under each layer of cooling nozzle is 7.78 seconds.

[0094] The upper limit of the total water flow of the first layer cooling nozzle 6 is 14L / s, and the upper limit of the total water flow of the second layer cooling nozzle 7 is 12L / s. The upper limit of the total water flow of the third layer cooling nozzle 8 is 10L / s. The upper limit of the total water flow of the fourth layer cooling nozzle 9 is 8L / s; according to the following two formulas ⑦⑧, the water flow in the cooling nozzle is open as follows: the third pneumatic valve 20 of the first layer cooling nozzle is fully open, the fourth pneumatic valve 21 of the second layer cooling nozzle is fully open, the fifth pneumatic valve 22 of the third layer cooling nozzle is fully open, and the sixth pneumatic valve 23 of the fourth layer cooling nozzle is 20.7% open:

[0095] 14 L / s *7.78S+12 L / s *7.78S+10 L / s *7.78S+1.66 L / s *7.78S =293L ⑦

[0096] 100%*1.66L / s / 8 L / s =20.7% ⑧

[0097] The number of steel bars facing the unloading side of the vertical lifting device is 11 layers. The target temperature of the steel bars at the fourth layer (at the end of the mist cooling) is controlled to be 630℃. The average cooling rate of the mist cooling section in the vertical lifting mechanism is controlled to be 9.64℃ / S. The mist cooling section has an accelerated cooling effect on the steel bar 5. In this temperature range and cooling rate, it is beneficial to grain refinement, but no bainite phase will be generated. The generated water vapor can react with the surface of the steel bars in the vertical lifting mechanism to form a dense Fe3O4 layer, which is beneficial to improve the corrosion resistance.

[0098] 3Fe+4H2O=Fe3O4+4H2

[0099] A water tank is arranged at the bottom of the vertical lifting mechanism to collect the aerosol spray cooling water dripping downward after cooling the steel bars. The water in the water tank flows into the water circulation device and is used again for steel bar aerosol cooling after being filtered.

[0100] After the steel bars were put down from the cooling bed, a 600mm long steel bar was taken to test the yield strength of the steel through a tensile test. The strength test results are shown in Table 1 below. Two 600mm long steel bars were taken to test the atmospheric corrosion resistance of the steel through an outdoor exposure test. The corrosion resistance is shown in Table 1 below. Figure 4a , Figure 4b , Figure 4c .

[0101] Comparative Example 1,

[0102] A steel plant produces rebar with the grade HRB400E, and the steel composition is: C: 0.23%, Si: 0.31%, Mn: 1.43%, V: 0.017%, N: 105ppm.

[0103] The finished steel bar after rolling has a diameter of Φ20mm. The double-cut rolling process is adopted, and the existing strong water-penetrating technology is used to produce threaded steel. There are three groups of water-penetrating water tanks, the first group is 7m long, the second group is 6m long, and the third group is 5.5m long. The total flow rate of cooling water in the control water tank is: 800~900m 3 / h water pressure is: 1.1 ~ 1.2MPa, the speed of the steel bar in the water tank is 13.5m / s, the amount of steel per hour is: 120 ~ 130 tons, the surface temperature of the steel bar before entering the water tank is 1000 ~ 1030 ℃, the surface temperature of the steel bar after passing through the water tank is 600 ~ 650 ℃, and the surface temperature of the steel bar after returning to temperature is 800 ~ 850 ℃. After passing through the water tank, the steel bar is transported to the cooling bed in the existing public technology for natural air cooling.

[0104] After the rebar is put down from the cooling bed, a 600mm long rebar is taken to test the yield strength of the steel through a tensile test. The strength test results are shown in Table 1 below. Two 600mm long rebars are taken to test the atmospheric corrosion resistance of the steel through an outdoor exposure test. The corrosion resistance is shown in Table 1 below. Figure 4a , 4b , 4c.

[0105] Comparative Example 2,

[0106] A steel plant produces rebar with the grade HRB400E, and the steel composition is: C: 0.23%, Si: 0.31%, Mn: 1.45%, V: 0.028%, N: 113ppm.

[0107] The existing pure hot rolling technology is used to produce rebar. The finished steel bar after rolling has a diameter of Φ20mm. The double-cut rolling process is adopted. No water cooling is performed after rolling. The running speed of the steel bar after finishing rolling is 13.5m / s. The steel passing capacity per hour is: 120-130 tons. The surface temperature of the steel bar after finishing rolling is 1030-1060℃, and the surface temperature of the steel bar on the cooling bed is 1010-1040℃. The rolled steel bar is transported to the cooling bed in the existing public technology for natural air cooling.

[0108] After the rebar is put down from the cooling bed, a 600mm long rebar is taken to test the yield strength of the steel through a tensile test. The strength test results are shown in Table 1 below. Two 600mm long rebars are taken to test the atmospheric corrosion resistance of the steel through an outdoor exposure test. The corrosion resistance is shown in Table 1 below. Figure 4a , 4b , 4c.

[0109] Table 1. Tensile properties of rolled materials in the examples and comparative implementations

[0110]

[0111] Comparing Example 1 with Comparative Example 1, the difference in steel composition and strength is not significant. Figure 4a , 4b , 4c. It can be seen that the atmospheric corrosion resistance of Example 1 and Comparative Example 1 is very different. It can be seen from the figure that after the steel bars produced in Example 1 were exposed outdoors for 60 days, the surface between the transverse ribs of the steel bars was still blue-black when leaving the factory. After the water-piercing steel bars produced in Comparative Example 1 were exposed outdoors for 60 days, the surface of the steel bars turned rust-red as a whole, and the rust was serious. The rust-proof ability of the steel bars produced in Example 1 was significantly stronger than that of the water-piercing steel bars produced in Comparative Example 1. The reason is as described in the background technology of the present invention. The water-piercing steel bars undergo a relatively drastic volume change during the strong cooling process of water-piercing, resulting in the shedding of iron oxide scale on the surface of the steel bars. Although a certain thickness of iron oxide scale will be generated again during the slow cooling process on the cooling bed after returning to temperature, the generated iron oxide scale is thin, poor in density, and poor in rust-proof ability. When the technology used in the present invention is used to produce steel bars, firstly, a light water penetration process is adopted. The cooling intensity during water penetration cooling is only 1 / 2 of the cooling intensity in comparative example 1. The volume change of the steel bars during the water penetration process is small, and the iron oxide layer on the surface of the steel bars is not easy to fall off. Secondly, the present invention performs aerosol cooling on the steel bars in the vertical lifting mechanism and generates water vapor. During the rising process of the water vapor, an oxidation reaction occurs with the surface of other steel bars to generate an Fe3O4 oxide layer. The number of steel bar layers in the vertical lifting mechanism is greater than 10 layers, and the reaction time between the steel bars and the water vapor is more than 60 seconds. Since the oxidizing property of water vapor is slightly worse than that of oxygen, it is beneficial to control the main component of the reaction product to be Fe3O4, rather than Fe2O3. The Fe3O4 layer The anti-rust ability is much stronger than Fe2O3, and a layer of dark black oxide (3Fe+4H2O=Fe3O4+4H2) will be formed on the surface of the steel part, and the mass proportion of oxygen in water vapor (the mass proportion of oxygen in water vapor is 94%) is much higher than the mass proportion of oxygen in air (the volume proportion of oxygen in air is 22%). The increase in the oxygen proportion is conducive to the large-scale generation of Fe3O4, so the generated oxide layer is thicker and denser, has better wear resistance and is not easy to fall off. Therefore, fumigating steel bars above 600°C in water vapor for more than 60 seconds can greatly improve the atmospheric corrosion resistance of the steel bar surface, which is obviously due to the atmospheric corrosion resistance of the water-piercing steel bars produced in Comparative Example 1.

[0112] Comparing Example 1 with Comparative Example 2, the strengths of Example 1 and Comparative Example 2 are similar, but the vanadium content in Example 1 is 0.012% lower than that in Comparative Example 2. According to the current vanadium alloy price (the price of vanadium-nitrogen alloy with a vanadium content of 77% is 168,000 yuan / ton), the cost of 0.012% vanadium is 26 yuan / ton of steel. The alloy cost of the steel bars produced in Example 1 is significantly lower than that in Comparative Example 2. The reason is that the steel bars produced in Comparative Example 2 are pure hot-rolled steel bars without water cooling and mist cooling. Although the original iron oxide layer will not fall off during the slow cooling process, the strength of the steel bars is sacrificed, and the technology of "increasing the strength of the steel bars by increasing the cooling rate and refining the grains before the transformation of austenite to ferrite + pearlite" is not used. The present invention performs three-stage cooling on the threaded steel after finish rolling, namely, light water cooling, mist cooling, and air cooling. The cooling rate gradually decreases from high temperature to low temperature. First, the cooling intensity of water cooling is reduced, which is beneficial to avoid the appearance of overcooling structure and reduce the occurrence of the oxide layer shedding on the surface of the steel bar. In the mist cooling section, a medium cooling rate is used to cool the steel bar, and the surface temperature of the steel bar in the mist cooling section is controlled to be higher than 600°C. Cooling the steel bar at a medium cooling rate in the mist cooling section can improve the strength of the steel bar without generating unqualified structures such as bainite, which is beneficial to saving alloy costs. The water vapor generated in the mist cooling section can generate a dense ferroferric oxide layer after reacting with the surface of the steel bar. Figure 4a , 4b 4c, it can be seen that the anti-rust ability of the steel bars produced by the present invention is slightly better than that of the pure hot-rolled steel bars in Comparative Example 2, and the anti-rust performance is also superior.

[0113] The process parameters (such as temperature, time, etc.) of the present invention can realize the method by taking upper and lower limits and interval values, and the embodiments are not listed one by one here.

[0114] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A device for improving the strength of threaded steel and the density of the surface oxide layer, characterized in that: include: The post-rolling light water penetration mechanism is used to perform preliminary light water penetration cooling on the rolled steel bars; A vertical lifting mechanism is used to accommodate and sequentially lift the steel bars that have passed through the post-rolling light water-piercing mechanism layer by layer; the vertical lifting mechanism includes a plurality of lifting assemblies arranged at intervals in the horizontal direction, the lifting assemblies are located between the steel unloading side and the cooling bed; the lifting assemblies are equipped with gravity sensing assemblies; An aerosol cooling mechanism is provided on each layer of the vertical lifting mechanism, and is used for performing aerosol cooling on each layer of steel bars passing through the vertical lifting mechanism.

2. The device according to claim 1, characterized in that The post-rolling light water-penetrating mechanism comprises two groups of water-penetrating water tanks, the length of the first group is 6 to 7 meters, and the length of the second group is 5 to 6 meters.

3. The device according to claim 1, characterized in that The device also includes a power mechanism for driving a plurality of lifting components to operate in a synchronous length and synchronous frequency manner.

4. The device according to claim 1, characterized in that The lifting assembly is composed of a driving gear, a driven gear, a chain and a plurality of steel support rods. The driving gear is located directly above the driven gear. The distance between the center point of the driving gear and the center point of the driven gear is 1.2-2m. The diameter of the tooth top circle of the driving gear is 30-40cm, the tooth spacing is 5-10cm, and the driving gear and the driven gear are the same in size and shape. The steel bar support rod is a rod-shaped object with a length of 10-20 cm and a spacing of 10-20 cm between adjacent steel bar support rods. The steel bar support rod is fixed on the chain and evenly distributed along the length direction of the chain. The straight line where the steel bar support rod is located is parallel to the plane where the driving gear is located. The angle between the steel bar support rod and the chain is 30-60°. The chain connects the driving gear and the driven gear in a circumferential manner. The chain drives the steel bar support rod to rotate along the two gears as the gears rotate.

5. The device according to claim 1, characterized in that The length of each layer of aerosol cooling mechanism is the same as the length of the cooling bed. Each layer of aerosol cooling mechanism includes a number of cooling nozzles. The spraying directions of the cooling nozzles are distributed in the direction of 35-50 degrees to the upper right, 35-50 degrees to the upper left, 35-50 degrees to the lower right, and 35-50 degrees to the lower left. The aerosol nozzles are aimed at each layer of steel bars in the lifting device. The distance between the cooling nozzle and the steel bar is 90-100mm, the spray angle of the cooling nozzle in the length direction of the steel bar is 90-110°, and the spacing between the cooling nozzles in the length direction of the steel bar is 160-200mm.

6. A system for improving the strength of threaded steel and the density of the surface oxide layer, characterized in that: include: A cooling control module, used to control the post-rolling light water penetration mechanism, the vertical lifting mechanism and the aerosol cooling mechanism in the device according to any one of claims 1 to 5; The cooling control module includes a temperature measuring unit, a flow meter, a pressure gauge, a pneumatic regulating valve and a cooling water quantity calculation unit; The temperature measuring unit includes measuring the temperature of the steel bar surface entering the vertical lifting mechanism and measuring the temperature of the steel bar surface at the end of the mist cooling; The cooling water volume calculation unit calculates the cooling water spray volume according to the target steel bar surface temperature setting value at the end of aerosol cooling, the actual detection value of the steel bar surface temperature entering the vertical steel bar lifting device, the actual detection value of the steel bar surface temperature at the end of aerosol cooling, and the production process parameters.

7. The system according to claim 6, characterized in that The cooling water quantity calculation unit comprises: (A) The amount of water spray required to cool the steel bar per unit length to the target temperature is proportional to the weight of the steel bar and the temperature drop caused by spray cooling: V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 -T 散 ) (B) The amount of heat that a unit length of steel bar dissipates into the air in a natural heat dissipation manner is proportional to the surface area of ​​the steel bar, the heat dissipation time, the steel bar temperature, and the heat dissipation coefficient of the steel: Q 散 =K2*N*t*2*3.14*r(T 目标 +T 进 ) / 2 (C) The amount of heat dissipated by a unit length of steel bar into the air by natural heat dissipation is proportional to the weight of the steel bar, the specific heat capacity of the steel bar, and the heat dissipation temperature drop: Q 散 =K3*N*7.85*3.14*r 2 *T 散 (D) and combining (A), (B) and (C), we get: V=K1*N*7.85*3.14*r 2 *(T 进 -T 目标 -K2*t(T 目标 +T 进 ) / (K3*7.85*r)) (E) When the mist cooling is finished, the temperature of the steel bar surface is detected and the corrected proportional coefficient is calculated: K 修正 =V / (N*7.85*3.14*r 2 *(T 进 -T 出 -K2*t(T 出 +T 进 ) / (K3*7.85*r))) (F) Total water supply for mist cooling: V 总 =V*L Where V is the amount of water spray required to cool the steel bar to the target temperature per decimeter, L / dm; K1 is the proportional coefficient L / (kg·℃); N is the number of steel bars on the single-layer steel bar support rod; r is the radius of the steel bar, dm; T 目标 is the target temperature setting value of the steel bar surface at the end of mist cooling, ℃; T 进 is the actual detected value of the steel bar surface temperature entering the vertical lifting mechanism, ℃; T 出 is the actual detected value of the steel bar surface temperature at the end of mist cooling, ℃; T 散 It is the temperature drop value caused by the natural heat dissipation of the steel bar to the air from the time when the steel bar enters the vertical lifting mechanism to the end of the mist cooling, ℃; Q 散 is the heat dissipated by the steel bar into the air in the form of natural heat dissipation per decimeter, W; K2 is the heat dissipation coefficient of the steel bar, W / dm 2 ·℃; t is the time from the steel bar entering the vertical lifting mechanism to the end of the mist cooling stage, s; K3 is the specific heat capacity of steel, J / (kg·℃); V 总 is the amount of water sprayed to cool the steel bars in the vertical lifting mechanism to the target temperature, L; L is the length of the vertical lifting mechanism, dm; K 修正 is the corrected proportionality coefficient, L / (kg·℃); if K 修正 If the offset between K1 and K2 exceeds 10%, the corrected proportionality factor K 修正 Instead of K1, (D) is used to calculate the amount of cooling water sprayed on the next steel bar entering the vertical lifting mechanism, and the real-time temperature of the steel bar surface at the end of subsequent aerosol cooling is continuously measured, and whether K1 needs to be corrected is calculated according to formula (E).

8. A method for improving the strength of threaded steel and the density of the surface oxide layer using the device according to any one of claims 1 to 5, comprising the following steps: After rolling, the steel bars are lightly water-penetrated and cooled by a post-rolling light water-penetration mechanism, and then the steel bars are lifted layer by layer by a vertical lifting mechanism. Each layer of steel bars passing through the vertical lifting mechanism is cooled by an aerosol cooling mechanism. After the steel bars are lifted to the last layer of the vertical lifting mechanism, they enter the cooling bed for cooling.

9. The method according to claim 8, characterized in that The total flow rate of cooling water in the water tank of the light water-penetrating mechanism is: 300~500m 3 / h, water pressure is: 0.6~1.0MPa, the running speed of steel bars in the water tank is 3~14m / s, the amount of steel passing per hour is: 100~150 tons, the surface temperature of the steel bars before entering the water tank is 950~1050℃, the surface temperature of the steel bars after leaving the water tank is 800~850℃, and the surface temperature of the steel bars after returning to temperature is 900~950℃.

10. The method according to claim 8, characterized in that The water pressure of the mist cooling mechanism is: 0.2~0.3Mpa, the gas pressure is: 0.3~0.4Mpa, and the gas flow rate is 10-15Nm 3 / ton of steel; The average cooling rate of the steel bars in the aerosol cooling section of the vertical lifting mechanism is 3.5-12℃ / s.

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