A full face immersion cooling system for hot rolling work rolls

Abstract

The application discloses a full-roller-face immersion cooling system for a hot-rolling work roller, which comprises a work roller upper roller, a work roller lower roller, and upper and lower water-cutting plates corresponding to the work roller upper roller and the work roller lower roller; the work roller upper roller is provided with an upper water collecting tank on one side, and the upper water collecting tank is provided with an upper spraying system and a water-cutting plate of the upper water collecting tank; the water-cutting plate of the upper water collecting tank and the roller surface of the work roller upper roller form an upper roller surface dynamic cooling water space; the work roller lower roller is provided with a lower water collecting tank on one side, and the lower water collecting tank is provided with a lower spraying system and a water-cutting plate of the lower water collecting tank; the water-cutting plate of the lower water collecting tank and the roller surface of the work roller lower roller form a lower roller surface dynamic cooling water space. The application aims at the extreme use efficiency of the roller, reduces the on-line loss of the work roller, prolongs the on-line use time and the roller replacement cycle, and improves the service life of the work roller.

Description

TECHNICAL FIELD

[0001] The present application relates to the hot strip rolling technology in the metallurgical industry, more particularly, to a full-face immersion cooling system for hot rolling work rolls. BACKGROUND

[0002] With the strong demand for high-end strip rolling products in the market, the current hot strip rolling production line capacity continues to increase, and the product material is constantly updated and diversified. This makes the rolling mill and the most important work roll face higher challenges, such as higher reduction force, reduction rate, longer online rolling time, shorter roll changing, maintenance, and maintenance time. Therefore, it is necessary to improve the rolling efficiency. One of the keys to improving efficiency is to increase the online use time of the work roll and reduce its online loss.

[0003] The existing hot strip high-speed steel work roll is widely used in the front stage of hot rolling finishing due to its high wear resistance and reliability. During use, the work roll surface temperature rises sharply to about 400-600℃ due to heat conduction with the strip during biting (as shown in Figure 1 ), and then the oxide film is generated on the roll body and roll surface due to the influence of oxygen, water vapor and cooling water in the air. Under the combined action of rolling force, slip and high temperature, the oxide film quickly transforms into a thin layer of oxide glaze. Under different rolling lines and rolling environments, the stable oxide glaze thickness is about 0.1-20μm. The development of oxide glaze during hot rolling is a dynamic process, which consists of formation in the initial stage of rolling, dynamic stability in the middle stage, and finally cracking and peeling. During the stable stage of its growth, the oxide glaze is worn and then leaves the biting area to enter the outlet end water cooling and immediately generates new oxide glaze, which is repeated, and the oxide glaze effectively protects the work roll surface. After a long time of rolling, the roll surface begins to appear tiny cracks due to thermal fatigue, and oxygen and water vapor enter the crack inside the roll surface and cause the material near the crack to oxidize (as shown in Figure 2 ). At the same time, the oxide glaze no longer stably grows-wears-regrows in a dynamic process, but starts to form irregularly and quickly with the increase of roll temperature, and a small part of it peels off, eventually leading to serious roll surface wear, as shown in Figure 3 (a) and the uneven color difference of the oxide glaze and the black and bright color shown in Figure 3 (b) is the oxide glaze, and the light-colored place is the work layer matrix exposed after the oxide glaze peels off. Therefore, roll changing and grinding operations must be performed.

[0004] The traditional work roll on-line cooling method is through high pressure and large water flow cooling mode. The cooling water flow of each finishing stand outlet of the hot strip finishing mill is about 5000-7000L / min, and the water pressure is about 8-18bar. Even so, the oxidation glaze on the work roll is difficult to maintain for a long time under the current high output, large pressure and long on-line conditions, and often cracks and meteor spots and other peeling phenomena occur, which seriously affect the roll consumption.

[0005] Therefore, how to efficiently use the roll, ensure the compactness and stability of the oxidation glaze on the roll surface, is the key to stable production, improve the roll surface and strip surface quality and improve the rolling efficiency. SUMMARY

[0006] In view of the defects in the prior art, the purpose of the present application is to provide a full roll surface immersion cooling system for hot rolling work rolls, aiming at the maximum use efficiency of the roll, reducing the on-line loss of the work roll, improving its service life, and prolonging the on-line use time and the roll changing cycle.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A full roll surface immersion cooling system for hot rolling work rolls, comprising a work roll upper roll, a work roll lower roll, and an upper water cutting plate and a lower water cutting plate corresponding to the work roll upper roll and the work roll lower roll;

[0009] One side of the work roll upper roll is provided with an upper water collecting tank, and the upper water collecting tank is provided with an upper spraying system and an upper water collecting tank water cutting plate;

[0010] The upper water collecting tank water cutting plate and the roll surface of the work roll upper roll form an upper roll surface dynamic cooling water space;

[0011] One side of the work roll lower roll is provided with a lower water collecting tank, and the lower water collecting tank is provided with a lower spraying system and a lower water collecting tank water cutting plate;

[0012] The lower water collecting tank water cutting plate and the roll surface of the work roll lower roll form a lower roll surface dynamic cooling water space.

[0013] Preferably, the upper water collecting tank and the lower water collecting tank are arranged on the outlet side of the strip.

[0014] Preferably, the upper water collecting tank is located above the upper water cutting plate;

[0015] The lower water collecting tank is located below the lower water cutting plate.

[0016] Preferably, the upper water collecting tank water cutting plate is arranged at the lower end of the upper water collecting tank;

[0017] The lower water collecting tank water cutting plate is arranged at the lower end of the lower water collecting tank.

[0018] Preferably, the upper water collecting tank and the lower water collecting tank correspond to the side surface of the upper work roll and the lower work roll as the spraying surface.

[0019] The spraying surface is provided with solid cylindrical nozzles or conical nozzles.

[0020] Preferably, the diameter of the nozzle of the solid cylindrical nozzle is 4-10 mm.

[0021] Preferably, the diameter of the nozzle of the conical nozzle is 4-10 mm, and the spray angle is 30-120°.

[0022] Preferably, the number of the nozzles is 58-320.

[0023] The spray outlet velocity of the nozzle is 2-32 m / s.

[0024] The spray flow of the nozzle is 6.3-25.8 L / min.

[0025] Preferably, the nozzle of the upper water collecting tank forms an angle of 90-130° with the axial direction of the upper work roll.

[0026] Preferably, the nozzle of the lower water collecting tank is perpendicular to the axial direction of the lower work roll.

[0027] Preferably, the spraying surface of the upper water collecting tank and the spraying surface of the lower water collecting tank are both 0-100 mm away from the roll surface of the upper work roll and the lower work roll.

[0028] The lower part of the spraying surface of the upper water collecting tank and the lower water collecting tank is tangent to the roll surface of the upper work roll and the lower work roll.

[0029] Preferably, the number of the stirring water outlets on the spraying surface of the upper water collecting tank is 12-90.

[0030] The diameter of the stirring water outlet on the spraying surface of the upper water collecting tank is 2-6 mm.

[0031] Preferably, the dynamic volume of the roll surface cooling water in the upper roll surface dynamic cooling water space and the lower roll surface dynamic cooling water space is 8-120 L.

[0032] Preferably, the water pressure of the upper spraying system and the lower spraying system is 1-12 bar.

[0033] Preferably, the upper work roll and the lower work roll are made of high-speed steel, high-lo steel or high-lo steel material.

[0034] The diameter of the upper work roll and the lower work roll is 300-1350mm, and the length of the roll body is 300-5500mm.

[0035] Preferably, the replacement frequency of the cooling water wrapped around the roll surface per unit time of the upper roll surface dynamic cooling water space and the lower roll surface dynamic cooling water space is as follows:

[0036] 10bar water pressure is implemented 1-9 times, and 2bar water pressure is implemented 0.5-4 times.

[0037] The full roll surface immersion cooling system for hot rolling work rolls provided by the application can improve the cooling condition of high-speed steel work rolls in the hot rolling process, improve the cooling efficiency, effectively reduce the roll body temperature and roll surface temperature, and thus keep the oxidation glaze stable and intact, so that the growth of the roll surface oxidation glaze is controllable, and the oxidation corrosion of the work layer caused by cracks is reduced. In turn, the roll surface of the high-speed steel work roll in the hot rolling strip rolling process can be better protected, the roll surface quality and rolling efficiency are improved, the oxidation corrosion of the work layer material inside caused by cracks is reduced, and the growth of the oxidation glaze is controlled. Therefore, through the improvement of the extreme cooling efficiency, the roll consumption can be reduced, the roll surface smoothness is maintained, and the service life of the roll is improved, and the roll surface quality of the rolled strip is achieved, reaching the extreme efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a schematic diagram of the existing rolling bite-in process and outlet roll cooling;

[0039] Figure 2 is a schematic diagram of the existing high-speed steel work roll surface cracks and the work layer matrix near the cracks having started to oxidize;

[0040] Figure 3 is a schematic diagram of the existing high-speed steel work roll surface cracks and oxidation glaze peeling, (a) is the roll surface cracks and oxidation glaze uneven color difference, (b) is the black and bright color is oxidation glaze, and the light color place is the work layer matrix exposed after oxidation glaze peeling;

[0041] Figure 4 is a structural schematic diagram of the full roll surface immersion cooling system of the application;

[0042] Figure 5 is a schematic diagram of the roll surface after the machine of the full roll surface immersion cooling system of the application and the traditional cooling method, (a) is the traditional cooling method, and (b) is the full roll surface immersion cooling system of the application. DETAILED DESCRIPTION

[0043] In order to better understand the above technical solutions of the application, the technical solutions of the application will be further described below in combination with the drawings and examples.

[0044] In combination withFigure 4 As shown, the present invention also provides a full-surface immersion cooling system for hot rolling work rolls, including an upper work roll 1, a lower work roll 2, and an upper cutting water plate 4 and a lower cutting water plate 5 corresponding to the upper work roll 1 and the lower work roll 2, wherein the hot-rolled strip 5 passes through the upper work roll 1 and the lower work roll 2 for rolling operations.

[0045] The upper working roll 1 and the lower working roll 2 are made of inexhaustible cold-hardened material (high-speed steel) or high-speed iron and high-speed steel.

[0046] The diameter range of the upper working roll 1 and the lower working roll 2 is 300 to 1350 mm.

[0047] The lengths of the upper working roll 1 and the lower working roll 2 are 300–5500 mm.

[0048] The upper water collection tank 6 is provided on the outlet side of the upper roller 1 of the working roller. The upper water collection tank 6 is equipped with an upper spray system and an upper water collection tank water cutter 8.

[0049] The upper water collection tank water cutting plate 8 and the roller surface of the upper roller 1 and the spray surface of the upper water collection tank 6 form a dynamic cooling water space 10 on the upper roller surface.

[0050] The outlet of the lower roller 2 of the working roller is provided with a lower water collection tank, and the lower water collection tank 7 is equipped with a lower spray system and a lower water collection tank cutter plate 9.

[0051] A dynamic cooling water space 11 is formed between the water cutting plate 9 of the lower water collection tank, the roller surface of the lower roller 2 of the working roller, and the spray surface of the lower water collection tank 7.

[0052] The upper water collection tank 6 is located above the upper water cutting plate 4, and the lower water collection tank 7 is located below the lower water cutting plate 5.

[0053] The water cut-off plate 8 of the upper water collection tank is located at the lower end of the upper water collection tank 6.

[0054] The water cut-off plate 9 of the lower water collection tank is located at the lower end of the lower water collection tank 7.

[0055] The upper water collection tank 6 and the lower water collection tank 7 correspond to the spray surfaces of the upper working roller 1 and the lower working roller 2.

[0056] Solid cylindrical nozzles or conical nozzles are provided on the spray surface.

[0057] When the nozzle is a solid cylindrical nozzle, its nozzle diameter is 4 to 10 mm.

[0058] When the nozzle is a conical nozzle, its nozzle diameter is 4-10 mm and the spray angle is 30-120°.

[0059] The number of nozzles ranges from 58 to 320.

[0060] The jetting outlet velocity of the nozzle is 2-32 m / s.

[0061] The jetting flow of the nozzle is 6.3-25.8 L / min.

[0062] The spray surface of the upper water collecting tank 6 forms an angle of 90-130° with the axial direction of the upper work roll 1.

[0063] The spray surface of the lower water collecting tank 7 is perpendicular to the axial direction of the lower work roll 3.

[0064] The spray surface of the upper water collecting tank 6 and the spray surface of the lower water collecting tank 7 are both 0-100 mm away from the roll surface of the upper work roll 1 and the lower work roll 2.

[0065] The lower part of the spray surface of the upper water collecting tank 6 and the lower part of the spray surface of the lower water collecting tank 7 are both tangent to the roll surface of the upper work roll 1 and the lower work roll 2.

[0066] The number of stirring water outlets on the spray surface of the upper water collecting tank 6 is 12-90.

[0067] The diameter of the stirring water outlets on the spray surface of the upper water collecting tank 7 is 2-6 mm.

[0068] The dynamic volume of the roll surface dynamic cooling water space 10 and the roll surface dynamic cooling water space 11 is 8-120 L.

[0069] The water pressure of the upper spray system and the lower spray system is 1-12 bar.

[0070] The replacement frequency of the roll surface dynamic cooling water space 10 and the roll surface dynamic cooling water space 11 within a unit time is as follows:

[0071] The water pressure is 10 bar and the replacement frequency is 1-9 times, and the water pressure is 2 bar and the replacement frequency is 0.5-4 times.

[0072] The cooling water replacement frequency refers to the flow rate of the cooling water in the gap between the roll surface and the spray surface within a unit time. The greater the replacement frequency, the higher the efficiency of heat exchange between the roll surface and the new cooling water, and the better the cooling effect.

[0073] The existing work roll cooling technology often uses high pressure water (10-18 bar) to cool the work roll by the impact force of the cooling water, or uses a large amount of water sprayed at a close distance by a dense nozzle. The present application is a full roll surface immersion cooling system which changes the traditional cooling water spraying mode on the guide at the rolling outlet, introduces a cooling water package for the roll surface, and increases the upper and lower water tank cutting plates 8 and 9 on the basis of the original water cutting plate, i.e. the entire roll surface of the upper roll 1 and the lower roll 2 at the outlet side is completely immersed in the cooling water, so that the roll surface and the spraying surface produce strong heat exchange to reduce the roll surface temperature, i.e. immersion quenching roll cooling. Thus, the crack caused by the thermal fatigue of the roll surface is effectively slowed down, and the oxidation and corrosion caused by the crack expansion to the inside of the work layer material of the roll are prevented. The roll surface is protected, and the surface quality of the hot-rolled strip is finally improved (e.g. reducing the scale inclusion on the surface of the strip, improving the surface smoothness, and improving the specifications of the strip, etc.).

[0074] The present application is a full roll surface immersion cooling system which improves the cooling efficiency, actively protects the oxidation glaze, and effectively reduces the roll body and roll surface temperature by using dynamic cooling water to immerse and wrap the roll surface, so that the entire roll surface oxidation glaze is uniformly distributed, and the hardness is constant.

[0075] The hardness uniformity (standard deviation) of the roll surface after the present application is used is compared with the hardness of the roll surface under the traditional rolling mode, as shown in Table 1. The results show that the more uniform the oxidation glaze thickness, the smaller the hardness deviation of the roll surface after the mill in the unground state. This method indirectly detects the oxidation glaze thickness of the roll surface after the mill by using the standard deviation method using a Lee's hardness tester (LD). The standard deviation of the roll surface hardness in the unground state under the traditional cooling water mode is more than 2.7%. The standard deviation of the roll surface hardness in the unground state under the present application is less than 1.9%. In addition, the hardness non-uniformity of the roll surface increases with the decrease of the pressure under the traditional cooling mode. The hardness of the roll body after the mill under the present application changes little with the change of the cooling water pressure.

[0076] Table 1 Comparison of hardness deviation of hot-rolled high-speed work roll in the unground state after the mill

[0077]

[0078] Comparison of the mill temperature. Each temperature measurement is about 20-30 minutes after the mill, and the measurement point is the middle part of the roll body. Compared with the traditional cooling mode, the present application can reduce the roll body temperature by about 5-16℃ on the basis of improving the online rolling time and rolling amount.

[0079] CombiningFigure 5 As shown, the same rack on different rollers under different cooling processes are compared, and it can be directly seen that the effect of the full roller surface immersion cooling system is obviously better than that of the traditional cooling mode.

[0080] Those skilled in the art of the present technology should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation of the present application, as long as the changes and modifications of the above described embodiments are within the scope of the spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A full-roller surface immersion cooling system for hot-rolled work rollers, comprising a work roller upper roller, a work roller lower roller, and an upper water cutting plate and a lower water cutting plate corresponding to the work roller upper roller and the work roller lower roller, characterized in that: one side of the work roller upper roller is provided with an upper water collecting tank, the upper water collecting tank is provided with an upper spraying system and an upper water collecting tank water cutting plate; the upper water collecting tank water cutting plate and the roller surface of the work roller upper roller form an upper roller surface dynamic cooling water space; one side of the work roller lower roller is provided with a lower water collecting tank, the lower water collecting tank is provided with a lower spraying system and a lower water collecting tank water cutting plate; the lower water collecting tank water cutting plate and the roller surface of the work roller lower roller form a lower roller surface dynamic cooling water space; the upper water collecting tank and the lower water collecting tank are arranged on the outlet side of the strip; the upper water collecting tank is located above the upper water cutting plate; the lower water collecting tank is located below the lower water cutting plate; the upper water collecting tank water cutting plate is arranged at the lower end of the upper water collecting tank; the lower water collecting tank water cutting plate is arranged at the lower end of the lower water collecting tank; the dynamic volume of the roller surface cooling water in the upper roller surface dynamic cooling water space and the lower roller surface dynamic cooling water space is 8-120L; the cooling water pressure of the upper spraying system and the lower spraying system is 1-12bar; the replacement frequency of the roller surface cooling water in the upper roller surface dynamic cooling water space and the lower roller surface dynamic cooling water space per unit time is as follows: 1-9 times for 10bar water pressure and 0.5-4 times for 2bar water pressure; the side surface of the upper water collecting tank and the lower water collecting tank corresponding to the work roller upper roller and the work roller lower roller is a spraying surface; the spraying surface is provided with solid cylindrical nozzles or conical nozzles; the nozzle diameter of the solid cylindrical nozzles is 4-10mm; the nozzle diameter of the conical nozzles is 4-10mm and the jet angle is 30-120°; the number of nozzles is 58-320; the jet exit velocity of the nozzles is 2-32m / s; the jet flow of the nozzles is 6.3-25.8L / min; the angle between the nozzles of the upper water collecting tank and the axial direction of the work roller upper roller is 90-130°; the nozzles of the lower water collecting tank are perpendicular to the axial direction of the work roller lower roller; the distance between the spraying surface of the upper water collecting tank and the spraying surface of the lower water collecting tank and the roller surface of the work roller upper roller and the work roller lower roller is 0-100mm; the lower part of the spraying surface of the upper water collecting tank and the spraying surface of the lower water collecting tank is tangent to the roller surface of the work roller upper roller and the work roller lower roller; the number of stirring water outlets on the spraying surface of the upper water collecting tank is 12-90; the diameter of the stirring water outlets on the spraying surface of the upper water collecting tank is 2-6mm; the work roller upper roller and the work roller lower roller are made of high-speed steel, high-lo iron or high-lo steel; the diameter of the work roller upper roller and the work roller lower roller is 300-1350mm and the roller body length is 300-5500mm. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. A full face immersion cooling system for a hot rolling work roll according to claim 1, characterized in that: ​ ​ 3. A full face immersion cooling system for a hot rolling work roll according to claim 2, characterized in that: ​ 4. A full face immersion cooling system for a hot rolling work roll as defined in claim 2 wherein: ​ 5. A full face immersion cooling system for a hot rolling work roll as defined in claim 2 wherein: ​ ​ ​ 6. A full face immersion cooling system for a hot rolling work roll as defined in claim 2 wherein: ​ 7. A full face immersion cooling system for a hot rolling work roll according to claim 6, characterized in that: ​ 8. A full face immersion cooling system for a hot rolling work roll according to claim 7, characterized in that: ​ ​ 9. A full face immersion cooling system for a hot rolling work roll according to claim 8, characterized in that: ​ ​ 10. A full face immersion cooling system for a hot rolling work roll as defined in claim 1 wherein: ​ ​

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