Furnace dredging method for improving nodulation of furnace roller of heat treatment furnace

Abstract

The invention discloses a furnace dredging method for improving accretion of a furnace roller of a heat treatment furnace, which is a method suitable for maintaining the furnace roller of a continuous heat treatment production line of thin and thick steel plates and the like, under the working condition that the temperature of a hearth of the heat treatment furnace is 800-930 DEG C, output of a hot tapping combustion system is stopped firstly, so that the heat treatment furnace is in a natural cooling state; the method comprises the following steps: carrying out furnace-through cooling by using a furnace-through flat plate steel plate, compacting nodules, carrying out furnace-through operation by using a special grooved steel plate when the temperature is reduced to 550-620 DEG C according to a given furnace entering sequence and an operation method by using the friction force between the grooved steel plate and the roller way, and effectively removing the nodules of the roller way in the furnace without stopping the furnace. According to the method, the nodules are polished through friction between the special steel plate and the roller way, furnace shutdown is not needed, the nodules of the roller way are safely, reliably and efficiently removed, the surface quality of the heat treatment process steel plate is improved, and the production efficiency of a heat treatment furnace is improved.

Description

Technical Field

[0001] This invention belongs to the field of steel technology, and in particular relates to a furnace ventilation method for improving furnace roll nodule formation in heat treatment furnaces. Background Technology

[0002] During long-term operation, oxide scale, rolling oil residue, or poorly controlled furnace atmosphere on the surface and sides of the steel plate in a heat treatment furnace can gradually adhere to the surface of the furnace rolls, forming hard nodules. These nodules can lead to quality defects such as indentations and scratches on the lower surface of the steel plate, severely affecting the product qualification rate and potentially causing unplanned downtime and reducing production efficiency.

[0003] Currently, the main method for dealing with furnace roller nodules is to periodically shut down the furnace and, after the furnace body has cooled, have operators enter the furnace to manually grind or scrape the rollers. This method has the following significant drawbacks:

[0004] 1. Inefficient and costly: It requires long production line shutdowns, and the cooling and reheating processes consume a lot of energy and time, resulting in huge output losses and energy waste.

[0005] 2. High labor intensity and harsh environment: Operators need to perform high-intensity physical labor in high-temperature and confined spaces, which poses safety risks. Moreover, the cleaning effect depends on the experience of the personnel, making it difficult to guarantee consistency.

[0006] 3. Affects furnace lining life: Frequent cooling and heating cycles will accelerate the damage to the furnace refractory material and shorten the furnace's service life.

[0007] Therefore, there is an urgent need to develop a method that can remove or suppress furnace roll nodules online, efficiently, and automatically to solve the above-mentioned technical problems.

[0008] Application No. 202410455001.9 discloses a method for online removal of nodules on the roller conveyor of a roller hearth heat treatment furnace. When the furnace temperature exceeds 800℃, a grinding roller steel plate is used. Utilizing the friction between the grinding roller steel plate and the roller conveyor, the grinding operation is performed according to a given furnace feeding sequence and operating method, effectively eliminating defects on the heat treatment furnace roller conveyor without shutting down the furnace. The grinding roller steel plate includes herringbone groove steel plates, narrow-thick steel plates, and wide-thick steel plates. The side of the herringbone groove steel plate in contact with the roller conveyor has multiple herringbone grooves, and the other side has a counterweight steel plate. The herringbone grooves grind the nodules on the roller conveyor. The side of the narrow-thick steel plate and the wide-thick steel plate in contact with the roller conveyor is a surface with a sandblasting cleaning grade of Sa2.5, used for grinding the roller conveyor. This invention utilizes the friction between the specially designed steel plate and the roller conveyor to grind the nodules, eliminating the need to stop the machine, achieving safe, reliable, and efficient removal of "nodules" from the roller conveyor, and improving the surface quality of the steel plates used in the heat treatment process. However, it has the following problems: the nodules soften due to high temperature and are not easy to remove completely; the grooving of the channeled steel plate is simple and inefficient; the nodules at the furnace door are more serious and the furnace passage plate is not completely removed, which will lead to incomplete furnace passage. Summary of the Invention

[0009] The purpose of this invention is to provide a furnace-clearing method to improve the removal of nodules on the furnace rollers of a heat treatment furnace. This method can automatically and efficiently remove nodules from the surface of the furnace rollers without shutting down the furnace or adding new furnace components, thereby significantly improving the surface quality of steel plates, reducing unplanned downtime, and lowering operating costs.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0011] This invention discloses a furnace clearing method to improve the removal of nodules on the furnace rollers of a heat treatment furnace. When the furnace temperature is between 800-930℃, the output of the hot-out combustion system is first stopped, allowing the heat treatment furnace to cool naturally. A furnace clearing plate is used to clear the furnace and cool it down, compacting the nodules. When the temperature drops to between 550-620℃, a grooved steel plate is used. The friction between the grooved steel plate and the roller conveyor is utilized to clear the furnace according to a given furnace entry sequence and operating method. This effectively eliminates defects in the heat treatment furnace roller conveyor without shutting down the furnace.

[0012] The furnace steel plate includes a grooved steel plate and a flat steel plate. The side of the grooved steel plate that contacts the roller conveyor is provided with multiple herringbone, inverted herringbone, and straight grooves. The herringbone, inverted herringbone, and straight grooves increase the contact area between the groove and the roller conveyor, thereby increasing the contact rate between the grooved part of the steel plate and the nodules on the roller conveyor and grinding the nodules on the roller conveyor. The side of the thick flat steel plate that contacts the roller conveyor is shot-blasted to a surface with a surface grade of Sa2.5 to grind the roller conveyor.

[0013] Furthermore, the channeled steel plate is available in two sizes: 60mm×2600mm×7000mm and 60mm×2200mm×10000mm.

[0014] Furthermore, the flat steel plate is available in six sizes: 50mm×2600mm×10000mm, 55mm×2600mm×10000mm, 60mm×2600mm×10000mm, 65mm×2600mm×10000mm, 70mm×2500mm×10000mm, 80mm×2500mm×10000mm, and 100mm×2200mm×6000mm.

[0015] 4. The furnace clearing method for improving furnace roller nodules in heat treatment furnaces according to claim 1, characterized in that the furnace clearing sequence is as follows: first, six flat steel plates are introduced into the furnace to cool down; after reaching the set temperature, 60mm×2200mm×10000mm channeled steel plates, 60mm×2600mm×7000mm channeled steel plates, and flat steel plates are introduced into the furnace in the order of thinnest to thickest.

[0016] Furthermore, the furnace operation method is as follows: the heat treatment furnace operator centers the steel plate entering the furnace, sets the running speed of the steel plate to 10m / min, completes the preparatory work before loading the furnace, and then loads the furnace at a speed of 10m / min; the steel plate entering the furnace is tracked on the HMI main control interface of the heat treatment furnace system, and when the head of the steel plate reaches the grating PC11 at the door of the unloading furnace, the unloading furnace door is opened and the furnace roller is adjusted to manual control mode with a speed of 10m / min.

[0017] Furthermore, the grooved steel plate is repeatedly ground three times between the roller conveyors in the heating and insulation zones of the furnace, and then retreats back into the furnace each time the tail reaches the furnace door.

[0018] Furthermore, the flat furnace steel plate does not need to run back and forth; it can pass through directly in one go.

[0019] Furthermore, after the furnace is opened, if the conditions for automatic unloading are met, the unloading is controlled normally through the HMI main control interface. If the conditions for automatic unloading are not met, the speed of the quenching machine and the speed of the roller conveyor in the furnace are manually matched for unloading.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0021] This invention provides an effective method for removing "nodules" from the roller conveyor within a furnace without shutting down the furnace. The method utilizes the friction between a specially designed steel plate and the roller conveyor to grind away the nodules. This eliminates the need to stop the furnace, ensuring safe, reliable, and efficient removal of nodules from the roller conveyor, thereby improving the surface quality of the steel plates used in the heat treatment process and increasing the production efficiency of the heat treatment furnace.

[0022] Other advantages, objectives, and features of the invention will be set forth in the following description, and to some extent will be apparent to those skilled in the art from the following examination and study, and may be learned from the practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the grooved steel plate (herringbone, inverted herringbone, straight groove) in this invention. Detailed Implementation

[0025] Steel plates undergoing heat treatment processes include loading, shot blasting, flipping, heat treatment, quenching, tempering, shearing and sampling, spraying (engraving), surface inspection, and packaging and warehousing. After passing physical and chemical tests, they are loaded and shipped.

[0026] During the production process in a heat treatment furnace, iron oxide scale adheres to the furnace bottom rollers, forming "nodules." These nodules can cause surface quality defects such as indentations and scratches on the heat-treated steel plates, necessitating cleaning. The technical parameters of the roller hearth heat treatment furnace are as follows:

[0027] Heat treatment furnace type: Roller hearth heat treatment furnace with nitrogen protection;

[0028] Applications of heat treatment furnaces: Heating of steel plates before normalizing, tempering, and quenching;

[0029] Specifications of heat-treated steel plates: Thickness 5-100mm, width 1200-3600mm, length 3000-19000mm;

[0030] Maximum heat treatment temperature: 950℃; Maximum furnace temperature: 980℃;

[0031] Fuel type: Natural gas.

[0032] The technical parameters of the furnace bottom roller are as follows:

[0033] Furnace roller diameter: Φ380×30mm, roller body length: 3810mm, furnace roller spacing: 580mm, speed of rollers under control in the furnace: 0.3~20m / min, roller material (DIN 1.4852) is alloy steel containing 25%Cr, 35%Ni and 1.5%Nb.

[0034] A method for improving nodule formation on the rollers of a heat treatment furnace involves, when the furnace temperature is between 800-930℃, first stopping the output of the hot-out combustion system to allow the furnace to cool naturally. A flat steel plate is then used to circulate the furnace, cooling and compacting the nodules. Once the temperature drops to between 550-620℃, a grooved steel plate is used. Utilizing the friction between the grooved steel plate and the rollers, the furnace is circulated according to a given feeding sequence and operating method. This method effectively eliminates roller defects in the heat treatment furnace without shutting down the furnace.

[0035] The furnace steel plates used are high-strength steel plates, including channeled steel plates and flat steel plates. The side of the flat steel plate that contacts the roller conveyor is a flat surface with a shot blasting grade of Sa2.5, and the roller conveyor is ground. The flat steel plates are available in six sizes: 50mm×2600mm×10000mm, 55mm×2600mm×10000mm, 60mm×2600mm×10000mm; 65mm×2600mm×10000mm, 70mm×2500mm×10000mm, 80mm×2500mm×10000mm; and 100mm×2200mm×6000mm.

[0036] Please see Figure 1 The side of the channeled steel plate that contacts the roller conveyor is provided with multiple herringbone, inverted herringbone, and straight grooves. The herringbone, inverted herringbone, and straight grooves are used to grind the nodules on the roller conveyor. The channeled steel plate is available in two sizes: 60mm×2600mm×7000mm and 60mm×2200mm×10000mm.

[0037] The furnace loading sequence is as follows: first, put 6 flat steel plates into the furnace to cool down; after reaching the desired temperature, put in 60mm×2200mm×10000mm channeled steel plates, 60mm×2600mm×7000mm channeled steel plates, and then put in flat steel plates in the order of thinnest to thickest.

[0038] The operation method of the grinding roller is as follows: The heat treatment furnace operator centers the steel plate entering the furnace, sets the running speed of the steel plate to 10m / min, completes the preparatory work before loading the furnace, and then loads the steel plate into the furnace at a speed of 10m / min; The steel plate entering the furnace is tracked on the HMI main control interface of the heat treatment furnace system. When the head of the steel plate reaches the grating PC11 at the door of the unloading furnace, the unloading furnace door is opened and the furnace roller is adjusted to manual control mode with a speed of 10m / min.

[0039] Finally, the grooved steel plate is repeatedly ground three times between the roller conveyors in the heating and heat preservation zones of the furnace, and then retreats back into the furnace each time the tail reaches the furnace door.

[0040] The steel plate of the flat furnace does not need to be moved back and forth; it can be passed through directly in one go.

[0041] After the furnace is opened, if the conditions for automatic unloading are met, the unloading is controlled normally through the HMI main control interface. If the conditions for automatic unloading are not met, the speed of the quenching machine and the speed of the roller conveyor in the furnace must be matched manually before unloading. Attention should be paid to the water spraying situation of the quenching machine to prevent the water spraying from causing the steel plate to deform.

[0042] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving furnace roller nodule formation in a heat treatment furnace, characterized in that, When the furnace temperature in the heat treatment furnace is 800-930℃, first stop the output of the hot-out combustion system and let the heat treatment furnace cool down naturally. Use a furnace-passing flat steel plate to pass through the furnace to cool it down and compact the nodules. When the temperature drops to 550-620℃, use a grooved steel plate and utilize the friction between the grooved steel plate and the roller conveyor to pass through the furnace according to the given furnace entry sequence and operation method. This effectively eliminates defects in the heat treatment furnace roller conveyor without stopping the furnace. The furnace steel plate includes a grooved steel plate and a flat steel plate. The side of the grooved steel plate that contacts the roller conveyor is provided with multiple herringbone, inverted herringbone, and straight grooves. The herringbone, inverted herringbone, and straight grooves increase the contact area between the groove and the roller conveyor, thereby increasing the contact rate between the grooved part of the steel plate and the nodules on the roller conveyor and grinding the nodules on the roller conveyor. The side of the thick flat steel plate that contacts the roller conveyor is shot-blasted to a surface with a surface grade of Sa2.5 to grind the roller conveyor.

2. The furnace unblocking method for improving furnace roller nodules in heat treatment furnaces according to claim 1, characterized in that, The channeled steel plate is available in two sizes: 60mm×2600mm×7000mm and 60mm×2200mm×10000mm.

3. The furnace unblocking method for improving furnace roller nodules in heat treatment furnaces according to claim 1, characterized in that, The flat steel plate is available in six sizes: 50mm×2600mm×10000mm, 55mm×2600mm×10000mm, 60mm×2600mm×10000mm, 65mm×2600mm×10000mm, 70mm×2500mm×10000mm, 80mm×2500mm×10000mm, and 100mm×2200mm×6000mm.

4. The furnace unblocking method for improving furnace roller nodules in a heat treatment furnace according to claim 1, characterized in that, The furnace loading sequence is as follows: first, put 6 flat steel plates into the furnace to cool down; after reaching the desired temperature, put in 60mm×2200mm×10000mm channeled steel plates, 60mm×2600mm×7000mm channeled steel plates, and then put in flat steel plates in the order of thinnest to thickest.

5. The furnace unblocking method for improving furnace roller nodules in a heat treatment furnace according to claim 1, characterized in that, The furnace operation method is as follows: The heat treatment furnace operator centers the steel plate entering the furnace, sets the running speed of the steel plate to 10m / min, completes the preparatory work before loading the furnace, and then loads the furnace at a speed of 10m / min; the steel plate entering the furnace is tracked on the HMI main control interface of the heat treatment furnace system. When the head of the steel plate reaches the grating PC11 at the door of the unloading furnace, the unloading furnace door is opened and the furnace roller is adjusted to manual control mode with a speed of 10m / min.

6. The furnace unblocking method for improving furnace roller nodules in a heat treatment furnace according to claim 5, characterized in that, Finally, the grooved steel plate is repeatedly ground three times between the roller conveyors in the heating and heat preservation zones of the furnace, and then retreats back into the furnace each time the tail reaches the furnace door.

7. The furnace unblocking method for improving furnace roller nodules in a heat treatment furnace according to claim 6, characterized in that, The steel plate of the flat furnace does not need to be moved back and forth; it can be passed through directly in one go.

8. The furnace unblocking method for improving furnace roller nodules in a heat treatment furnace according to claim 7, characterized in that, After the furnace is opened, if the conditions for automatic unloading are met, the unloading is controlled normally through the HMI main control interface. If the conditions for automatic unloading are not met, the speed of the quenching machine and the speed of the roller conveyor in the furnace are manually matched for unloading.

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