A heat treatment furnace bottom roller cooling device and process

Abstract

The application provides a heat treatment furnace bottom roller cooling device and process, relates to the field of mechanical manufacturing, and comprises a compressed air circulation pipe network and an asbestos fiber roller. The asbestos fiber roller comprises an alloy roller and a fiber layer wrapped on the surface of the alloy roller. The center of the alloy roller is provided with a central cooling air channel penetrating along the length direction of the alloy roller. The two ends of the central cooling air channel are connected to the compressed air circulation pipe network. A plurality of surface cooling air channels are arranged along the length direction of the alloy roller. The plurality of surface cooling air channels are close to the fiber layer and are communicated with the central cooling air channel. The application can reduce the temperature difference between the roller core and the roller surface, reduce the risk of high-temperature-resistant asbestos fiber cracking, prolong the service life, and reduce energy consumption due to the improved cooling uniformity and reduced heat removal in the furnace.

Description

Technical Field

[0001] This invention relates to the field of machinery manufacturing, and more specifically, to a heat treatment furnace bottom roller cooling device and process. Background Technology

[0002] With the continuous improvement of the national economy, the demand for high-performance, high-quality, and thick steel plates has been increasing year by year. In order to obtain good performance and quality, heat treatment processes such as quenching and tempering, normalizing and tempering, and normalizing are often required. Common heat treatment furnaces are mainly roller hearth heat treatment furnaces, walking beam heat treatment furnaces, and trolley heat treatment furnaces. Among them, roller hearth heat treatment furnaces have been widely used by major steel mills in China due to their advantages such as uniform heating, controlled furnace atmosphere, low energy consumption, and high production efficiency. However, during production and use, the iron oxide scale remaining on the lower surface of the steel plate will adhere and accumulate on the surface of the furnace bottom roller made of high-temperature alloy steel. After being rolled by the steel plate, it will form nodules and irregular bumps. When the steel plate passes through the nodulated furnace roller during heat treatment, pits will be generated, resulting in furnace bottom roller imprint defects on the lower surface. These defects may require grinding, affecting the steel plate delivery cycle and surface quality, or even lead to the scrapping of the steel plate.

[0003] The inventors discovered that to address the problem of nodule formation on the furnace bottom rollers, some manufacturers use a method of repeatedly running the furnace through grooved steel plates after cooling the heat treatment furnace to 400-500℃. This method not only involves a slow cooling process, affecting the furnace's operating rate, but also easily scratches the furnace bottom roller surface. Nodules easily reappear shortly after removal, requiring repeated cooling and furnace runs every 7-10 days on average, severely impacting production efficiency. Some manufacturers use high-temperature resistant fiber furnace rollers, available in non-water-permeable and water-permeable types. The non-water-permeable type effectively solves the nodule formation problem on the furnace bottom roller surface, but it cannot effectively cool the roller, causing the heat-resistant fibers on the roller surface to crack and shortening its service life. The water-permeable fiber roller extends its service life by cooling the center of the roller with water, but the cooling process cannot effectively cool the roller surface, creating a temperature difference within the roller body. After a period of use, the roller body deforms, causing the fiber roller surface to crack again. Furthermore, using industrial circulating water leads to scaling on the furnace rollers and pipes, affecting the cooling effect. Summary of the Invention

[0004] The purpose of this invention is to provide a cooling device and process for the bottom roller of a heat treatment furnace, which can reduce the temperature difference between the roller core and the roller surface, reduce the risk of cracking of high-temperature resistant asbestos fibers, extend service life, and reduce energy consumption due to improved cooling uniformity and reduced heat removal from the furnace.

[0005] The embodiments of the present invention are implemented as follows:

[0006] In a first aspect, the present invention provides a heat treatment furnace bottom roller cooling device, comprising:

[0007] Compressed air circulation pipeline network;

[0008] An asbestos fiber roller, comprising an alloy roller and a fiber layer wrapped around the surface of the alloy roller, wherein the center of the alloy roller is provided with a central cooling air passage extending along its own length, and the two ends of the central cooling air passage are connected to the compressed air circulation network through air pipes.

[0009] The alloy roller is also provided with multiple surface cooling air channels arranged along its own length, and the multiple surface cooling air channels are close to the fiber layer and connected to the central cooling air channel.

[0010] In an optional embodiment, four surface cooling channels are provided, which are evenly and equidistantly distributed on the alloy roller and close to the fiber layer.

[0011] In an optional embodiment, the diameter of the central cooling air channel is 1 / 4 to 1 / 5 of the alloy roller, and the diameter of the central cooling air channel is 2 to 3 times that of the surface cooling air channel.

[0012] In an optional embodiment, the alloy roller is provided with a plurality of cross-shaped air channels along its own length direction, and each cross-shaped air channel is connected to four surface cooling air channels and the central cooling air channel.

[0013] In an optional embodiment, the cross-shaped air passage is at a 45° angle to the side of the central cooling air passage.

[0014] In an optional embodiment, a total of 10 to 20 cross-shaped air channels are provided, and they are equidistantly arranged along the length direction of the alloy roller. The diameter of the cross-shaped air channels is 1 / 10 to 1 / 20 of the diameter of the surface cooling air channels.

[0015] In an optional embodiment, an air thermometer is installed on the ventilation duct, and an air flow control solenoid valve is installed at the connection between the ventilation duct and the air circulation network.

[0016] Secondly, the present invention provides a heat treatment furnace bottom roller cooling process, including any of the heat treatment furnace bottom roller cooling devices described in any of the above-mentioned claims, the steps of which are as follows:

[0017] S1: When the heat treatment furnace temperature is between 200 and 550°C, cooling is not required during this stage, and the air inlet flow rate is 0 m³ / s. 3 / h, air flow rate 0m 3 / h;

[0018] S2: When the heat treatment furnace temperature exceeds 550℃, the compressed air circulation network is activated. Specifically, when the heat treatment furnace temperature is between 551℃ and 700℃, the inlet air temperature is ≤25℃, the outlet air temperature is controlled between 25℃ and 50℃, and the inlet air flow rate is controlled between 100℃ and 150 m³ / h. 3 / h, with the outlet flow rate controlled between 95 and 145 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 ;

[0019] When the heat treatment furnace temperature is 701–800℃, the inlet gas temperature should be ≤25℃, the outlet gas temperature should be controlled between 25–45℃, and the inlet gas flow rate should be controlled between 270–320. 3 / h, with the outlet flow rate controlled between 265 and 315 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 ;

[0020] When the heat treatment furnace temperature is 801~950℃, the inlet gas temperature should be ≤25℃, the outlet gas temperature should be controlled between 25~40℃, and the inlet gas flow rate should be controlled between 295~345. 3 / h, with the outlet flow rate controlled between 290 and 340 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 .

[0021] In an optional implementation, the heat-treated steel plate must be shot-blasted and pre-straightened before entering the furnace. The surface roughness of the upper and lower surfaces of the steel plate must reach Sa2.5 level and the flatness must reach 2mm / 1m before entering the furnace.

[0022] In an optional implementation, the heat treatment furnace must be purged with nitrogen during operation to create a slightly positive pressure inside the furnace, ensuring that the residual oxygen content inside the furnace is ≤100ppm, the nitrogen purity is ≥99.99%, the nitrogen pressure is 0.3~0.5Mpa, and the furnace pressure is 10~25Pa.

[0023] The beneficial effects of the embodiments of the present invention are:

[0024] This invention provides a furnace bottom roller cooling device, comprising: a compressed air circulation network and an asbestos fiber roller, wherein the asbestos fiber roller includes an alloy roller and a fiber layer wrapped around the surface of the alloy roller; by using a breathable and high-temperature resistant asbestos fiber roller, and taking advantage of the certain elasticity of the surface of the asbestos fiber roller, the iron oxide scale on the lower surface of the steel plate cannot form compacted nodules on the surface of the asbestos fiber roller, thereby eliminating the furnace bottom roller mark defect on the lower surface of the heat treatment plate.

[0025] In addition, a central cooling air channel running along the length of the alloy roller is provided at its center, with both ends connected to a compressed air circulation network. Multiple surface cooling air channels also run along the length of the alloy roller, all located close to the fiber layer and connected to the central cooling air channel. During production, the air inlet flow rate is controlled to be slightly greater than the outlet flow rate, maintaining a slight positive pressure in the ventilation pipes to ensure that compressed gas fills the entire asbestos fiber roller. This slight positive pressure in the surface cooling air channels and ventilation pipes improves the uniformity and efficiency of roller cooling.

[0026] In addition, the gas temperature in the inlet and outlet pipes is dynamically adjusted to ensure that the temperature of the high-temperature alloy roller of the asbestos fiber roller at the furnace bottom remains below 550°C. When the inlet temperature is too high, the power of the gas cooling equipment is increased; when the outlet temperature is too high, the flow control solenoid valve increases the inlet flow rate, and vice versa. This operating method, combined with the above structure, avoids the problem of surface fiber layer cracking caused by roller deformation, while reducing energy consumption. This not only extends its service life to 12-15 months, but also avoids repeated heating and cooling of the heat treatment furnace, effectively improving the furnace's operating rate and increasing the output of heat-treated plates. Furthermore, the gas consumption is 15% lower than that of water-cooled high-temperature fiber rollers.

[0027] Finally, using a compressed air circulation network instead of industrial circulating water for roller cooling avoids the problem of scale buildup in the cooling pipes due to the high impurity content of industrial circulating water, thus further extending the service life. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a first-view schematic diagram of the heat treatment furnace bottom roller cooling device provided in an embodiment of the present invention;

[0030] Figure 2 This is a second-view schematic diagram of the heat treatment furnace bottom roller cooling device provided in an embodiment of the present invention.

[0031] icon:

[0032] 100 - Compressed air circulation pipeline; 200 - Asbestos fiber roller; 210 - Alloy roller; 211 - Central cooling air passage; 212 - Surface cooling air passage; 213 - Cross-shaped air passage; 220 - Fiber layer; 300 - Ventilation pipe; 400 - Air thermometer; 500 - Air flow control solenoid valve. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] like Figure 1 and Figure 2 As shown, this embodiment provides a heat treatment furnace bottom roller cooling device, including: a compressed air circulation network 100 and an asbestos fiber roller 200. The asbestos fiber roller 200 includes an alloy roller 210 and a fiber layer 220 wrapped around the surface of the alloy roller 210. A central cooling air channel 211 is provided in the center of the alloy roller 210, extending along its own length. The two ends of the central cooling air channel 211 are connected to the compressed air circulation network 100 through air pipes 300. Multiple surface cooling air channels 212 are also provided inside the alloy roller 210, extending along its own length. All surface cooling air channels 212 are close to the fiber layer 220 and connected to the central cooling air channel 211. Specifically, one end of the surface cooling air channel 212 can be connected to the air inlet pipe of the compressed air circulation network 100, while the other end is closed. Therefore, the compressed air in the surface cooling air channel returns to the compressed air circulation network 100 through the central cooling air channel 211.

[0040] Understandably, this embodiment utilizes a breathable, high-temperature resistant asbestos fiber roller 200. Taking advantage of the inherent elasticity of the asbestos fiber roller 200 surface, the iron oxide scale on the lower surface of the steel plate cannot form compacted nodules on the asbestos fiber roller 200 surface. Furthermore, the use of the breathable, high-temperature resistant asbestos fiber roller 200 eliminates the furnace bottom roller imprint defect on the lower surface of the heat-treated plate. Simultaneously, the surface cooling air passage 212 improves the uniformity and efficiency of roller cooling, avoiding cracking of the surface fiber layer 220 caused by roller deformation. This also reduces energy consumption, extending its service life to 12-15 months, avoiding repeated heating and cooling of the heat treatment furnace, effectively improving the furnace's operating rate, increasing heat-treated plate production, and reducing gas consumption by 15% compared to water-cooled high-temperature resistant fiber rollers. In addition, using a compressed air circulation network 100 instead of industrial circulating water for roller cooling avoids the problem of scale buildup in the cooling pipes caused by impurities in industrial circulating water, further extending its service life.

[0041] Specifically, four surface cooling air channels 212 are provided, and the four surface cooling air channels 212 are evenly and equidistantly distributed on the alloy roller 210 and close to the fiber layer 220.

[0042] It should be noted that in this embodiment, four surface cooling air channels 212 are provided, but it is not limited to this. In other embodiments, there may be five, six, etc. Any scheme that is equivalent to this embodiment and can achieve the effect of this embodiment is within the protection scope of this embodiment.

[0043] Furthermore, the diameter of the central cooling air passage 211 is 1 / 4 to 1 / 5 of that of the alloy roller 210. It is understood that the specific diameter of the central cooling air passage 211 is determined according to the actual working conditions. If the temperature of the asbestos fiber roller 200 is high in the actual working conditions, the diameter of the central cooling air passage 211 can be appropriately increased, and vice versa.

[0044] Specifically, the diameter of the central cooling air passage 211 is 2 to 3 times that of the surface cooling air passage 212. It is understandable that, since the compressed gas in the surface cooling air passage 212 is discharged through the central cooling air passage 211, in order to quickly discharge the compressed gas in both the surface cooling air passage 212 and the central cooling air passage 211 and improve the cooling effect, the diameter of the central cooling air passage 211 must be 2 to 3 times larger than the diameter of the surface cooling air passage 212. The exact number depends on the compressed air supplied by the compressed air circulation network 100.

[0045] In this embodiment, the alloy roller 210 is provided with multiple cross-shaped air channels 213 along its length. Each cross-shaped air channel 213 connects four surface cooling air channels 212 and a central cooling air channel 211. It is understood that the purpose of providing multiple cross-shaped air channels 213 connecting the surface cooling air channels 212 and the central cooling air channel 211 is to allow the heat from the roller surface to be better discharged through the central cooling air channel 211, reducing the temperature difference between the roller core and the roller surface, decreasing the risk of cracking of the high-temperature asbestos fibers, and further improving cooling uniformity.

[0046] Specifically, the cross-shaped air passage 213 forms a 45° angle with the side of the central cooling air passage 211. It can be understood that this angle between the cross-shaped air passage 213 and the central cooling air passage 211 reduces the resistance encountered by the compressed air in the surface cooling air passage 212 when entering the central cooling air passage 211, allowing the compressed air in the surface cooling air passage 212 to quickly exchange heat and cool the surface temperature of the asbestos fiber roller 200. Finally, this embodiment has determined 45° to be the optimal angle through multiple experiments.

[0047] Specifically, a total of 10 to 20 cross-shaped air channels 213 are provided, and they are equidistantly arranged along the length of the alloy roller 210. The diameter of the cross-shaped air channels 213 is 1 / 10 to 1 / 20 of the diameter of the surface cooling air channels 212. It is worth noting that in this embodiment, the number of cross-shaped air channels 213 is inversely proportional to the diameter of the cross-shaped air channels 213. When the number of cross-shaped air channels 213 is 15, the diameter of the cross-shaped air channels 213 is 1 / 15 of the diameter of the surface cooling air channels 212. This matching setting is beneficial for heat exchange between the central cooling air channel 211 and the surface cooling air channel 212.

[0048] In this embodiment, an air thermometer 400 is installed on the ventilation duct 300. It is understood that the air thermometer 400 is mainly used to measure the temperature of compressed air; there are two air thermometers 400, which are respectively installed on the ventilation duct 300 connected to both ends of the central cooling air duct 211, and are used to detect the temperature of the compressed air entering the central cooling air duct 211 and the temperature of the compressed air exiting the central cooling air duct 211.

[0049] In this embodiment, an air flow control solenoid valve 500 is installed at the connection between the ventilation pipe 300 and the air circulation network. Specifically, the purpose of installing the air flow control solenoid valve 500 is to control the flow rate of compressed air, so that the asbestos fiber roller 200 can achieve the best cooling effect under different operating conditions and improve the service life of the equipment.

[0050] Specifically, alloy roll 210 is a roll made of tungsten carbide and cobalt as materials by powder metallurgy.

[0051] In addition, through repeated experiments, this embodiment designs the diameter of the central cooling air passage 211 to be 1 / 5 of the diameter of the high-temperature alloy roller 210, balancing cooling effect and processing cost. Simultaneously, to facilitate the entry of compressed air from the surface cooling air passage 212 into the central air passage, the diameter of the central cooling air passage 211 is designed to be twice that of the surface cooling air passage 212. The diameter of the cross-shaped air passages 213 depends on their number. Figure 1 There are 18 herringbone-shaped air channels, the diameter of which is 1 / 18 of that of the near-surface air channels. The side angle between the cross-shaped air channel 213 and the central cooling air channel 211 is 45°. The central cooling air channel 211 and the surface cooling air channel 212 carry away the heat in the roller body through heat exchange. During the production process, the air inlet flow rate is controlled to be slightly greater than the air outlet flow rate so that the entire ventilation pipe 300 is in a slightly positive pressure state, ensuring that the cooling gas fills the entire air channel, which plays a role in uniformly cooling the roller body of the asbestos fiber roller 200, so that the temperature of the alloy roller 210 is always uniformly kept below 550°C. Within this temperature range, the high-temperature creep phenomenon of the roller body is not obvious and no deformation occurs.

[0052] This embodiment also provides a cooling process for the bottom rollers of a heat treatment furnace. Details are as follows:

[0053] S1: When the heat treatment furnace temperature is between 200 and 550°C, cooling is not required during this stage and can be maintained at 0 m³ / h. 3 / h, air flow rate 0m 3 / h;

[0054] S2: When the heat treatment furnace temperature exceeds 550℃, the compressed air circulation network is activated. Specifically, when the heat treatment furnace temperature is between 551℃ and 700℃, the inlet air temperature is ≤25℃, the outlet air temperature is controlled between 25℃ and 50℃, and the inlet air flow rate is controlled between 100℃ and 150m³. 3 / h, with the outlet flow rate controlled between 95 and 145 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 ;

[0055] When the heat treatment furnace temperature is between 701 and 800℃, the inlet gas temperature should be ≤25℃, the outlet gas temperature should be controlled between 25 and 45℃, and the inlet gas flow rate should be controlled between 270 and 320. 3 / h, with the outlet flow rate controlled between 265 and 315 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 ;

[0056] When the heat treatment furnace temperature is between 801 and 950℃, the inlet gas temperature should be ≤25℃, the outlet gas temperature should be controlled between 25 and 40℃, and the inlet gas flow rate should be controlled between 295 and 345. 3 / h, with the outlet flow rate controlled between 290 and 340 m³ / h. 3 / h, Inlet flow rate - Outlet flow rate ≥ 5m³ 3 .

[0057] It is worth noting that during the production process, by controlling the air intake flow rate to be slightly greater than the air output flow rate, the ventilation pipe 300 is kept in a slightly positive pressure state, ensuring that the compressed gas fills the entire asbestos fiber roller 200.

[0058] The gas temperature in the inlet and outlet pipes is dynamically adjusted to ensure that the temperature of the high-temperature alloy roller 210 of the asbestos fiber roller 200 at the bottom of the furnace is below 550℃. When the inlet temperature is too high, the power of the gas cooling equipment is increased. When the outlet temperature is too high, the flow control solenoid valve increases the inlet flow rate, and vice versa.

[0059] According to the air cooling formula: L=Q / [Cp×∝×(T1-T2)] (L: cooling air flow rate, Q: heat carried away, Cp: specific heat capacity of air, ∝: specific gravity of air, T1: temperature of air after cooling, T2: temperature of air before cooling), the heat carried away by the alloy roller 210 is Q=C×M×(T3-T4) (C: specific heat capacity of alloy steel, M: mass of alloy layer, T3: temperature of alloy layer before cooling, T4: temperature of air alloy layer after cooling).

[0060] The air outlet temperature in the ventilation pipe 300 should not exceed 50℃. Since the high-temperature resistant fiber layer 220 will exhibit high-temperature creep at temperatures above 550℃, causing the furnace roller to deform slowly, the furnace roller cooling should be turned on when the heat treatment furnace temperature exceeds 550℃. In order to balance cooling efficiency and operating costs, a control setting is set every 100-150℃.

[0061] Furthermore, before the heat-treated steel plates are put into the furnace, they must undergo shot blasting and pre-straightening treatment. The surface roughness of the upper and lower surfaces of the steel plates must reach Sa2.5 level and the flatness must reach 2mm / 1m.

[0062] Furthermore, during the operation of the heat treatment furnace, nitrogen must be purged inside the furnace to create a slightly positive pressure state, ensuring that the residual oxygen content inside the furnace is ≤100ppm, the nitrogen purity is ≥99.99%, the nitrogen pressure is 0.3~0.5Mpa, and the furnace pressure is 10~25Pa.

[0063] The present invention will be further described in detail below with reference to specific embodiments.

[0064] 1. Producing 2000 tons of CCSE550 steel, 6-100mm thick, with a heat treatment process of quenching and tempering. The quenching temperature is 930℃, and the tempering temperature is 660℃. Before entering the furnace, each steel plate is shot-blasted and pre-straightened to ensure that each plate surface is free of iron oxide scale, with a roughness of Sa2.5 grade and a straightness ≤2mm / 1m. During quenching, the inlet gas temperature is monitored and controlled below 25℃, while the outlet gas temperature is monitored and kept within the range of 30-40℃. During tempering, the outlet gas temperature is controlled at 40-50℃, and the nitrogen pressure is controlled and the nitrogen flow rate is stabilized to ensure that the residual oxygen in the furnace is ≤100ppm during quenching and tempering, and the furnace pressure is stabilized at 10-25Pa. After production, no steel plates showed any defects such as furnace bottom roller marks, and the surface quality was good.

[0065] 2. Production of 5000t of 16MnDR steel, 6-80mm thick, heat treatment process: normalizing at 900℃. Before entering the furnace, each steel plate is shot-blasted and pre-straightened to ensure no iron oxide scale on the surface, a roughness of Sa2.5 grade, and a straightness ≤2mm / 1m. During normalizing, the inlet gas temperature is monitored and controlled below 25℃, while the outlet gas temperature is monitored and kept within the range of 30-40℃. Simultaneously, nitrogen pressure is controlled, nitrogen flow is stabilized, residual oxygen in the furnace is kept ≤100ppm, and furnace pressure is stabilized at 10-25Pa. After production, no steel plates showed any defects such as furnace bottom roller marks, and the surface quality was excellent.

[0066] The apparatus and method for eliminating furnace bottom roller marks provided in this embodiment have the following advantages:

[0067] This embodiment uses a breathable and high-temperature resistant asbestos fiber roller 200. Taking advantage of the elasticity of the surface of the asbestos fiber roller 200, the iron oxide scale on the lower surface of the steel plate cannot form a compacted nodule on the surface of the asbestos fiber roller 200, thus eliminating the furnace bottom roller mark defect on the lower surface of the heat treatment plate.

[0068] In addition, a central cooling air channel 211 extending along the length of the alloy roller 210 is provided at its center. The two ends of the central cooling air channel 211 are connected to the compressed air circulation network 100. Multiple surface cooling air channels 212, also extending along the length of the alloy roller 210, are also provided inside the roller. These surface cooling air channels 212 are all close to the fiber layer 220 and connected to the central cooling air channel 211. Simultaneously, during production, by controlling the inlet air flow rate to be slightly greater than the outlet air flow rate, the ventilation pipe 300 is kept in a slightly positive pressure state, ensuring that compressed gas fills the entire asbestos fiber roller 200. The slightly positive pressure state within the surface cooling air channels 212 and the ventilation pipe 300 improves the uniformity and efficiency of roller cooling.

[0069] In addition, the gas temperature in the inlet and outlet pipes is dynamically adjusted to ensure that the temperature of the high-temperature alloy roller 210 of the asbestos fiber roller 200 at the furnace bottom remains below 550°C. When the inlet temperature is too high, the power of the gas cooling equipment is increased; when the outlet temperature is too high, the flow control solenoid valve increases the inlet flow rate, and vice versa. This operating method, combined with the above structure, avoids the problem of cracking of the surface fiber layer 220 caused by roller deformation, while reducing energy consumption. This not only extends its service life to 12-15 months and avoids repeated heating and cooling of the heat treatment furnace, effectively improving the furnace's operating rate and increasing the output of heat-treated plates, but also reduces gas consumption by 15% compared to water-cooled high-temperature fiber rollers.

[0070] Finally, the use of compressed air circulation network 100 to replace industrial circulating water for roller cooling avoids the problem of scale buildup in cooling pipes due to the high impurity content of industrial circulating water, which affects the cooling effect and further extends the service life.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat treatment furnace bottom roller cooling device, characterized in that, include: Compressed air circulation pipeline network; An asbestos fiber roller, comprising an alloy roller and a fiber layer wrapped around the surface of the alloy roller, wherein the center of the alloy roller is provided with a central cooling air passage extending along its own length, and the two ends of the central cooling air passage are connected to the compressed air circulation network through air pipes. The alloy roller is also provided with multiple surface cooling air channels arranged along its own length direction. The multiple surface cooling air channels are close to the fiber layer and connected to the central cooling air channel. The surface cooling air channels are evenly and equidistantly distributed on the alloy roller and close to the fiber layer. The alloy roller is provided with multiple cross-shaped air channels along its own length direction. Each cross-shaped air channel is connected to multiple surface cooling air channels and the central cooling air channel.

2. The heat treatment furnace bottom roller cooling device according to claim 1, characterized in that, The surface cooling air channels are provided in four ways, and the four surface cooling air channels are evenly and equidistantly distributed on the alloy roller and close to the fiber layer.

3. The heat treatment furnace bottom roller cooling device according to claim 1, characterized in that, The diameter of the central cooling air channel is 1 / 4 to 1 / 5 of the alloy roller, and the diameter of the central cooling air channel is 2 to 3 times that of the surface cooling air channel.

4. The heat treatment furnace bottom roller cooling device according to claim 1, characterized in that, The cross-shaped air passage is at a 45° angle to the side of the central cooling air passage.

5. A heat treatment furnace bottom roller cooling device according to claim 1, characterized in that, A total of 10 to 20 cross-shaped air channels are provided, and they are equidistant along the length of the alloy roller. The diameter of the cross-shaped air channel is 1 / 10 to 1 / 20 of the surface cooling air channel.

6. The heat treatment furnace bottom roller cooling device according to claim 1, characterized in that, An air temperature measuring instrument is installed on the ventilation duct, and an air flow control solenoid valve is installed at the connection between the ventilation duct and the air circulation network.

7. A cooling process for the bottom rollers of a heat treatment furnace, characterized in that, The heat treatment furnace bottom roller cooling device according to any one of claims 1 to 6 comprises the following steps; S1: When the temperature of the heat treatment furnace is 200~550℃, cooling is not required during this stage. The inlet air flow rate is 0m³ / h and the outlet air flow rate is 0m³ / h. S2: When the temperature of the heat treatment furnace is higher than 550℃, the compressed air circulation network is turned on. When the temperature of the heat treatment furnace is 551~700℃, the inlet air temperature is ≤25℃, the outlet air temperature is controlled at 25~50℃, the inlet air flow rate is controlled at 100~150m³ / h, the outlet air flow rate is controlled at 95~145m³ / h, and the inlet air flow rate minus the outlet air flow rate is ≥5m³ / h. When the temperature of the heat treatment furnace is 701~800℃, the inlet gas temperature is ≤25℃, the outlet gas temperature is controlled at 25~45℃, the inlet gas flow rate is controlled at 270~320m³ / h, the outlet gas flow rate is controlled at 265~315m³ / h, and the inlet gas flow rate minus the outlet gas flow rate is ≥5m³ / h. When the heat treatment furnace temperature is 801~950℃, the inlet gas temperature is ≤25℃, the outlet gas temperature is controlled at 25~40℃, the inlet gas flow rate is controlled at 295~345m³ / h, the outlet gas flow rate is controlled at 290~340m³ / h, and the inlet gas flow rate minus the outlet gas flow rate is ≥5m³ / h.

8. The heat treatment furnace bottom roller cooling process according to claim 7, characterized in that, Before entering the furnace, heat-treated steel plates must undergo shot blasting and pre-straightening treatment. The surface roughness of the upper and lower surfaces of the steel plates must reach Sa2.5 grade, and the flatness must reach 2mm / 1m.

9. The heat treatment furnace bottom roller cooling process according to claim 8, characterized in that, When the heat treatment furnace is in operation, nitrogen must be purged into the furnace to create a slightly positive pressure state, ensuring that the residual oxygen content in the furnace is ≤100ppm, the nitrogen purity is ≥99.99%, the nitrogen pressure is 0.3~0.5MPa, and the furnace pressure is 10~25Pa.

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