Full-roll-surface immersion type cooling system for hot rolling working roll

Abstract

The invention discloses a full roll surface immersion type cooling system for a hot rolling working roll, which comprises a working roll upper roll, a working roll lower roll, an upper water cutting plate and a lower water cutting plate, the upper water cutting plate and the lower water cutting plate correspond to the working roll upper roll and the working roll lower roll, and one side of the working roll upper roll is provided with an upper water collecting tank; an upper spraying system and an upper water collecting tank water cutting plate are arranged on the upper water collecting tank; an upper roll surface dynamic cooling water space is formed between the upper water collecting tank water cutting plate and the roll surface of the working roll upper roll; a lower water collecting tank is arranged on one side of the lower working roll, and a lower spraying system and a lower water collecting tank water cutting plate are arranged on the lower water collecting tank; and a lower roll surface dynamic cooling water space is formed between the water cutting plate of the lower water collecting tank and the roll surface of the lower roll of the working roll. According to the method, the purpose of the extreme use efficiency of the roller is achieved, the online loss of the working roller is reduced, the service life of the working roller is prolonged, the online use time is prolonged, and the roller replacement period is prolonged.

Description

Technical Field

[0001] The invention relates to hot-rolled strip rolling (steel rolling) technology in the metallurgical industry, and more specifically to a full-roller-surface immersion cooling system for hot-rolled working rolls. Background Art

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

[0003] Existing hot-rolled strip high-speed steel work rolls are widely used in the front section of hot rolling finishing due to their high wear resistance and reliability. Figure 1 (as shown) causes the temperature of the roller surface to suddenly rise to about 400-600℃ at this stage, and then, affected by the oxygen, water vapor and cooling water in the air, an oxide film will be generated on the roller body and roller surface. Under the combined action of the rolling force, slip and high temperature of the rolling mill, the oxide film will quickly transform into a thin layer of oxide glaze. Under different rolling lines and rolling environments, the thickness of the stable oxide glaze is about 0.1-20μm. The development of oxide glaze during hot rolling is a dynamic process, consisting of forming in the initial stage of rolling, dynamic stability in the middle stage, and finally cracking and peeling. In the stable stage of its growth, the oxide glaze is worn during each bite and then leaves the bite interval to enter the water cooling at the outlet end and immediately generates new oxide glaze, and so on, one increases while the other decreases, effectively protecting the roller surface of the high-speed steel working roller. When tiny cracks begin to appear on the roller surface due to thermal fatigue after a long period of rolling, oxygen and water vapor enter the cracks on the roller surface and oxidize the material near the cracks (such as Figure 2 At the same time, the oxide glaze no longer undergoes a stable growth-wear-regeneration dynamic process, but begins to form irregularly and rapidly with the increase of roller temperature, and a small part of it peels off, eventually leading to severe wear on the roller surface, such as Figure 3 (a) The roller surface cracks and uneven color difference of the oxide glaze and Figure 3 The black and bright color shown in (b) is the oxide glaze, and the light-colored area is the exposed working layer matrix after the oxide glaze peels off. This requires the roller replacement and grinding operation.

[0004] The traditional online cooling method for working rolls is through high-pressure and large-volume cooling. The cooling water volume at the outlet of each finishing stand of the hot strip finishing mill is as high as 5000-7000L / min, and the water pressure is as high as 8-18bar. Even so, the oxide glaze on the working roll is difficult to maintain for a long time under the current high production, large reduction and long-term online conditions, and often cracks and meteor spots and other peeling phenomena occur, which seriously affects the roll consumption.

[0005] Therefore, how to use the rollers efficiently and ensure the density and stability of the oxide glaze on the roller surface is the key to stabilizing production, improving the quality of the roller surface and plate and strip roller surface, and improving rolling efficiency. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a full-roll surface immersion cooling system for hot rolling working rolls, with the purpose of maximizing the utilization efficiency of the rolling rolls, reducing the online loss of the working rolls, increasing their service life, and extending the online use time and the roll changing cycle.

[0007] To achieve the above object, the present invention adopts the following technical solution:

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

[0009] An upper water collecting box is provided on one side of the upper roll of the working roll, and an upper spraying system and an upper water collecting box water cutting plate are provided on the upper water collecting box;

[0010] An upper roll surface dynamic cooling water space is formed between the water cutting plate of the upper water collecting box and the roll surface of the upper roll of the working roll;

[0011] A lower water collecting box is provided on one side of the lower roll of the working roll, and a lower spraying system and a water cutting plate of the lower water collecting box are provided on the lower water collecting box;

[0012] A lower roll surface dynamic cooling water space is formed between the water cutting plate of the lower water collecting box and the roll surface of the lower roll of the working roll.

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

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

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

[0016] Preferably, the water cut-off plate of the upper water collecting tank 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 side surfaces of the upper water collecting box and the lower water collecting box corresponding to the upper working roll and the lower working roll are spraying surfaces;

[0019] The spray surface is provided with a solid cylindrical nozzle or a conical nozzle.

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

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

[0022] Preferably, the number of the nozzles is 58 to 320;

[0023] The jet outlet velocity of the nozzle is 2 to 32 m / s;

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

[0025] Preferably, an angle of 90 to 130° is formed between the nozzle of the upper water collecting box and the axial direction of the upper roll of the working roll.

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

[0027] Preferably, the spray surface of the upper water collecting box and the spray surface of the lower water collecting box are both 0 to 100 mm away from the roller surface of the upper working roller and the lower working roller;

[0028] The spray surface of the upper water collecting box and the lower part of the spray surface of the lower water collecting box are both tangent to the roller surfaces of the upper working roller and the lower working roller.

[0029] Preferably, the number of stirring water outlets on the spray surface of the upper water collecting tank is 12 to 90;

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

[0031] Preferably, the dynamic volume of the upper roller surface dynamic cooling water space and the lower roller surface dynamic cooling water space for wrapping the roller surface cooling water is 8 to 120L.

[0032] Preferably, the cooling water pressure of the upper spray system and the lower spray system is 1 to 12 bar.

[0033] Preferably, the upper working roll and the lower working roll are made of high-speed steel, high-speed steel iron or high-speed steel;

[0034] The diameters of the upper working roll and the lower working roll are 300-1350 mm, and the lengths of the roll bodies are 300-5500 mm.

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

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

[0037] The full-roller-surface immersion cooling system for hot-rolled working rolls provided by the present invention improves the cooling conditions of the high-speed steel working rolls during hot rolling, improves the cooling efficiency, effectively reduces the roller body temperature and roller surface temperature, and thus maintains the integrity and stability of the oxide glaze, so that the growth of the roller surface oxide glaze is controllable, and reduces the oxidation corrosion caused by cracks inside the working layer. It can better protect the roller surface of the high-speed steel working roll during the hot-rolled plate and strip rolling process, improve the roller surface quality and rolling efficiency, reduce the oxidation corrosion inside the working layer material due to the generation of tortoise cracks, and control the growth of oxide glaze. Therefore, by improving the extreme cooling efficiency, it is possible to reduce roller consumption, maintain the roller surface finish, and thus improve the service life of the roller, and the roller surface quality of the rolled strip can achieve extreme efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the existing rolling bite process and the cooling of the exit roll;

[0039] Figure 2 It is a schematic diagram showing that cracks appear on the roll surface of an existing high-speed steel work roll and the working layer matrix near the cracks has begun to oxidize;

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

[0041] Figure 4 It is a structural schematic diagram of the full-roll surface immersion cooling system of the present invention;

[0042] Figure 5 The following is a schematic diagram comparing the lower roll surface of the full roll surface immersion cooling system of the present invention and the traditional cooling method, (a) is the traditional cooling method, and (b) is the full roll surface immersion cooling system of the present invention. DETAILED DESCRIPTION

[0043] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0044] Combination Figure 4 As shown, the present invention also provides a full-roll immersion cooling system for hot-rolled working rolls, including an upper working roll 1, a lower working roll 2, and an upper water cutting plate 4 and a lower water cutting plate 5 arranged corresponding to the upper working roll 1 and the lower working roll 2. The hot-rolled strip 5 passes between the upper working roll 1 and the lower working roll 2 for rolling.

[0045] The upper working roll 1 and the lower working roll 2 are made of infinitely cold hardened material (high speed steel) or high-speed iron or 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 roll lengths of the upper working roll 1 and the lower working roll 2 are 300 to 5500 mm.

[0048] An upper water collecting box 6 is provided at the outlet side of the upper roll 1 of the working roll, and an upper spraying system and an upper water collecting box cut-off plate 8 are arranged on the upper water collecting box 6 .

[0049] An upper roll surface dynamic cooling water space 10 is formed between the upper water collecting box water cutting plate 8, the roll surface of the upper roll 1 of the working roll, and the spraying surface of the upper water collecting box 6.

[0050] A lower water collecting box is provided at the outlet of the lower roll 2 of the working roll. A lower spraying system is arranged on the lower water collecting box 7, and a water cutting plate 9 for the lower water collecting box is arranged.

[0051] A lower roll surface dynamic cooling water space 11 is formed between the lower water collecting box cut-off plate 9 and the roll surface of the lower work roll 2 and the spraying surface of the lower water collecting box 7 .

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

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

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

[0055] The sides of the upper water collecting box 6 and the lower water collecting box 7 corresponding to the upper working roll 1 and the lower working roll 2 are spraying surfaces.

[0056] A solid cylindrical nozzle or a conical nozzle is arranged on the spraying surface.

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

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

[0059] The number of nozzles is 58 to 320.

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

[0061] The spray flow rate of the nozzle is 6.3~25.8L / min.

[0062] An angle of 90 to 130° is formed between the spraying surface of the upper water collecting box 6 and the axial direction of the upper roll 1 of the working roll.

[0063] The spraying surface of the lower water collecting box 7 is perpendicular to the axial direction of the lower roll 3 of the working roll.

[0064] The spraying surface of the upper water collecting box 6 and the spraying surface of the lower water collecting box 7 are both 0 to 100 mm away from the roller surfaces of the upper working roller 1 and the lower working roller 2.

[0065] The lower parts of the spraying surface of the upper water collecting box 6 and the spraying surface of the lower water collecting box 7 are tangent to the roll surfaces of the upper working roll 1 and the lower working roll 2.

[0066] The number of stirring water inlets on the spraying surface of the upper water collecting tank 6 is 12 to 90.

[0067] The diameter of the stirring water inlet on the spraying surface of the upper water collecting tank 7 is 2 to 6 mm.

[0068] The dynamic volume of the upper roller surface dynamic cooling water space 10 and the lower roller surface dynamic cooling water space 11 for wrapping the roller surface cooling water is 8 to 120 L.

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

[0070] The replacement frequency of the cooling water wrapped around the roll surface in the upper roll surface dynamic cooling water space 10 and the lower roll surface dynamic cooling water space 11 per unit time is as follows:

[0071] 10 bar water pressure is applied 1 to 9 times, and 2 bar water pressure is applied 0.5 to 4 times.

[0072] The frequency of cooling water replacement refers to the flow rate of cooling water in the gap between the roll surface and the spray surface per 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] Existing working roll cooling technology often uses high-pressure water (10-18 bar) to cool the working rolls through the impact force of cooling water, or by using dense nozzles to spray large amounts of water at close range. The full roll surface immersion cooling system of the present invention changes the traditional cooling water spraying method on the rolling exit guide, introduces the use of cooling water to wrap the roll surface, and adds the upper water collecting box water cutting plate 8 and the lower water collecting box water cutting plate 9 on the spray surface on the basis of the original water cutting plate, that is, the entire roll surface on the exit side of the working roll upper roll 1 and the working roll lower roll 2 is completely immersed in the cooling water, so that the roller surface temperature is reduced by a strong heat exchange between the spraying surface and the roll surface, that is, immersion quenching roll cooling. Thereby, the cracks caused by thermal fatigue of the roll surface are efficiently slowed down, and the oxidation and corrosion caused by the cracks extending into the material of the working layer of the roll are protected. The roll surface is then protected, and the surface quality of the hot-rolled strip is finally improved (for example, reducing the inclusion of iron oxide scale on the strip surface, improving the surface finish, and improving the strip specifications, etc.)

[0074] The full roller surface immersion cooling system of the present invention improves cooling efficiency and actively protects oxide glaze. It uses dynamic cooling water to immerse and wrap the roller surface to generate a strong heat exchange method to efficiently reduce the temperature of the roller body and roller surface, so that the oxide glaze on the entire roller surface is evenly distributed in thickness and the hardness is constant.

[0075] The uniformity (standard deviation) of the hardness of the roller surface after the full roller surface immersion cooling system of the present invention is compared with the roller surface hardness under the traditional rolling method, as shown in Table 1 below. The results show that the more uniform the oxide glaze thickness is, the smaller the hardness deviation is in the unground state after the machine is removed. This indirect method of detecting the thickness of the oxide glaze on the roller surface of the working roller after the machine is removed by the standard deviation method uses a Lee hardness tester (LD). The standard deviation of the roller surface hardness in the unground state of the roller surface measured under the traditional cooling water method is all above 2.7%. However, the standard deviation of the hardness of the roller surface in the unground state after the machine is removed using the full roller surface immersion cooling system of the present invention is all below 1.9%. In addition, in the traditional cooling method, the unevenness of the roller surface hardness increases with the decrease of pressure. However, the roller body hardness under the full roller surface immersion cooling system of the present invention reacts less to the change in cooling water pressure, and the hardness does not change much under different water pressures.

[0076] Table 1 Comparison of roll surface hardness deviation of hot rolling high-speed steel work rolls before grinding

[0077]

[0078] Comparison of the temperature after the machine is off. Each temperature measurement is about 20 to 30 minutes after the machine is off, and the measuring point is the middle of the roller body. Compared with the traditional cooling method, the full-roller surface immersion cooling system of the present invention can reduce the roller body temperature by about 5 to 16°C on the basis of increasing the online rolling time and rolling amount.

[0079] Combination Figure 5 As shown, a comparison of the roller surface conditions under different cooling processes of different rollers on the same frame is shown. It can be intuitively seen that the effect of the full roller surface immersion cooling system of the present invention is significantly better than that of the roller surface of the traditional cooling method.

[0080] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A full-roll immersion cooling system for hot rolling work rolls, comprising an upper work roll, a lower work roll, and an upper water cut plate and a lower water cut plate corresponding to the upper work roll and the lower work roll, characterized in that: An upper water collecting box is provided on one side of the upper roll of the working roll, and an upper spraying system and an upper water collecting box water cutting plate are provided on the upper water collecting box; An upper roll surface dynamic cooling water space is formed between the water cutting plate of the upper water collecting box and the roll surface of the upper roll of the working roll; A lower water collecting box is provided on one side of the lower roll of the working roll, and a lower spraying system and a water cutting plate of the lower water collecting box are provided on the lower water collecting box; A lower roll surface dynamic cooling water space is formed between the water cutting plate of the lower water collecting box and the roll surface of the lower roll of the working roll.

2. The full roll surface immersion cooling system for hot rolling working rolls according to claim 1 is characterized in that: The upper water collecting tank and the lower water collecting tank are both arranged on the outlet side of the plate strip.

3. The full roll surface immersion cooling system for hot rolling working rolls according to claim 2 is characterized in that: The upper water collecting tank is located above the upper water cutting plate; The lower water collecting box is located below the lower water cutting plate.

4. The full roll surface immersion cooling system for hot rolling work rolls according to claim 3 is characterized in that: The upper water collecting tank cut-off 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.

5. The full roll surface immersion cooling system for hot rolling working rolls according to claim 4 is characterized in that: The sides of the upper water collecting box and the lower water collecting box corresponding to the upper working roll and the lower working roll are spraying surfaces; The spray surface is provided with a solid cylindrical nozzle or a conical nozzle.

6. The full roll surface immersion cooling system for hot rolling working rolls according to claim 5 is characterized in that: The nozzle diameter of the solid cylindrical nozzle is 4 to 10 mm.

7. The full roll surface immersion cooling system for hot rolling working rolls according to claim 5 is characterized in that: The nozzle diameter of the conical nozzle is 4-10 mm, and the spray angle is 30-120°.

8. The full roll surface immersion cooling system for hot rolling working rolls according to claim 5 is characterized in that: The number of the nozzles is 58 to 320; The jet outlet velocity of the nozzle is 2 to 32 m / s; The spray flow rate of the nozzle is 6.3-25.8 L / min.

9. The full roll surface immersion cooling system for hot rolling working rolls according to claim 5, characterized in that: An angle of 90 to 130° is formed between the nozzle of the upper water collecting box and the axial direction of the upper roll of the working roll.

10. The full roll surface immersion cooling system for hot rolling working rolls according to claim 9, characterized in that: The nozzle of the lower water collecting box is perpendicular to the axial direction of the lower roll of the working roll.

11. The full roll surface immersion cooling system for hot rolling working rolls according to claim 10, characterized in that: The spray surface of the upper water collecting box and the spray surface of the lower water collecting box are both 0 to 100 mm away from the roller surface of the upper working roll and the lower working roll; The spray surface of the upper water collecting box and the lower part of the spray surface of the lower water collecting box are both tangent to the roller surfaces of the upper working roller and the lower working roller.

12. The full roll surface immersion cooling system for hot rolling working rolls according to claim 11, characterized in that: The number of stirring water outlets on the spray surface of the upper water collecting tank is 12 to 90; The diameter of the stirring water inlet on the spraying surface of the upper water collecting tank is 2 to 6 mm.

13. The full roll surface immersion cooling system for hot rolling working rolls according to claim 1, characterized in that: The dynamic volume of the upper roller surface dynamic cooling water space and the lower roller surface dynamic cooling water space for wrapping the roller surface cooling water is 8 to 120L.

14. The full roll surface immersion cooling system for hot rolling working rolls according to claim 1, characterized in that: The cooling water pressure of the upper spray system and the lower spray system is 1 to 12 bar.

15. The full roll surface immersion cooling system for hot rolling working rolls according to claim 1, characterized in that: The upper working roll and the lower working roll are made of high-speed steel, high-speed iron or high-speed steel; The diameters of the upper working roll and the lower working roll are 300-1350 mm, and the lengths of the roll bodies are 300-5500 mm.

16. The full roll surface immersion cooling system for hot rolling working rolls according to claim 13, characterized in that: The replacement frequency of the cooling water wrapped around the roll surface in the upper roll surface dynamic cooling water space and the lower roll surface dynamic cooling water space per unit time is as follows: 10 bar water pressure is applied 1 to 9 times, and 2 bar water pressure is applied 0.5 to 4 times.

Images