Method for eliminating roll build-up in a roller hearth heat treatment furnace

Abstract

The application discloses a method for eliminating the roller nodules of a roller hearth heat treatment furnace, comprising the following steps: setting up the furnace plate; making four groups of furnace plates, wherein each group of furnace plates comprises four plate bodies with different thicknesses; profiling the middle line position of each plate body in the width direction to make a profiled plate, and then performing shot blasting treatment on each profiled plate; arranging the profiled plates of the first group of furnace plates on a furnace front roller way in the order from high to low thickness, and then performing furnace passing after the profiled plates with different thicknesses are placed in a staggered manner with a distance of 450-550 mm; after the first group of furnace plates is discharged, the profiled plates of the second group, the third group and the fourth group of furnace plates are arranged in the arrangement mode of the previous group of furnace plates, and then furnace passing is sequentially performed after the profiled plates are oppositely staggered with the previous group of furnace plates; after the profiled plates of the fourth group of furnace plates are discharged, the temperature in the furnace is detected, and then furnace passing is recycled again when the temperature in the furnace is greater than 500 DEG C; and the furnace passing is ended when the temperature in the furnace is less than or equal to 500 DEG C. The method can remove the roller nodules of the furnace roller in a high quality and high efficiency, and prolong the service life of the furnace roller.

Description

Technical Field

[0001] This application relates to the field of heat treatment processes, and more particularly to a method for eliminating nodules on the rollers of a roller hearth heat treatment furnace. Background Technology

[0002] As market demands for steel appearance quality increase, the surface quality requirements for steel plates are becoming increasingly stringent. Due to the inability to precisely control factors such as the quality of steel plates entering the furnace or the furnace atmosphere, furnace rollers are prone to oxidation and nodule formation, resulting in pits on the lower surface of the steel plates and affecting their appearance quality. To eliminate these pit defects, existing technologies often employ two methods: long-term tempering with cooling or furnace shutdown and grinding of the furnace bottom rollers. However, both of these methods interrupt production and significantly impact production efficiency. Currently, there is also a method using furnace plates to eliminate nodule formation on furnace rollers. This method often involves using a large-sized furnace plate to pass through the furnace rollers, removing the nodules through the relative friction between the furnace plate and the rollers. However, large-sized furnace plates cannot cover a large area of ​​the furnace rollers, resulting in poor removal efficiency. Summary of the Invention

[0003] Technical problem to be solved: Existing technologies are not effective in removing nodules from furnace rollers, so the purpose of this application is to provide a method with better nodule removal effect.

[0004] Technical solution: This application discloses a method for eliminating furnace roller nodules in a roller hearth heat treatment furnace, comprising the following steps: Step 1: Setting up the furnace plates: Four sets of furnace plates are made using a heat-resistant material different from that of the furnace rollers. Each set of furnace plates consists of four plates of different thicknesses. The first plate is 81-99 mm thick, the second is 54-66 mm thick, the third is 27-33 mm thick, and the fourth is 9-11 mm thick. The width of each plate is the length of the furnace roller minus 450-550 mm, and the length of each plate is 6000-12000 mm. Step 2: Pre-treatment of furnace plates: Each plate is split along the centerline in the width direction to make split plates, and then each split plate is shot blasted. Step 3: Furnace Roller Removal Treatment: Arrange the split plates of the first group of furnace-passing plates in descending order of thickness on the furnace front roller conveyor. The split plates of different thicknesses are staggered by 450-550mm before furnace passage. After the first group of furnace-passing plates exits the furnace, arrange the split plates of the second, third, and fourth groups of furnace-passing plates in the same way as the previous group of furnace-passing plates, staggered relative to the previous group of furnace-passing plates, and then pass them through the furnace in sequence. Step 4: Temperature detection: After the furnace is circulated through the split plate of the fourth furnace plate, the furnace temperature is detected. If the furnace temperature is greater than 500℃, return to step 3; if the furnace temperature is less than or equal to 500℃, the furnace circulation is ended.

[0005] Preferably, the furnace plate is made of carbon steel with a carbon content of 0.25 to 0.60 wt%.

[0006] Preferably, the shot blasting speed in step two is 2 m / min; the surface quality of the split plate after the blasting process is SA2.0.

[0007] Preferably, in step three, the split plates of the same width furnace plates in each group of furnace plates are symmetrically arranged along the center line of the width direction of the furnace roller track; Preferably, in step three, the split plates of the second, third, and fourth groups of furnace plates are misaligned relative to the previous group of furnace plates, and this misalignment is in the direction of the width of the furnace roller track.

[0008] Preferably, in step three, the speed of the furnace roller conveyor plate during furnace passage is set to 5 m / min.

[0009] Beneficial effects: By splitting and staggering the furnace plate, the furnace plate can be in contact with the furnace roller to the maximum extent, thereby achieving the most efficient cooling and friction effect and realizing high-quality and efficient removal of furnace roller nodules; by setting different thickness gradients of the furnace plate, the impact load on the furnace roller is reduced, avoiding the impact on the service life of the furnace roller. Attached Figure Description

[0010] Figure 1 This is a flowchart of the method for eliminating furnace roll nodules in this application; Figure 2 This is a diagram illustrating the misalignment of the split plate in an embodiment of this application. Detailed Implementation

[0011] The technical solution of this application will be further described below with reference to the accompanying drawings.

[0012] Example 1 like Figure 1 As shown, the specific experimental methods used in the following embodiments are as follows: Four sets of furnace plates were fabricated, each set consisting of four steel plates: the first plate was 90mm thick, the second 60mm thick, the third 30mm thick, and the fourth 10mm thick. The steel plates were used to physically cool the furnace rollers and the nodules. The difference in shrinkage rate during cooling, caused by the material difference between the nodules and the furnace rollers, was used to remove the nodules. At the same time, a suitable thickness gradient of the furnace plates was selected to reduce the impact of different thickness steel plates on the furnace rollers.

[0013] The width of the steel plate is the length of the furnace roll minus 500mm. Since the furnace roll has a certain degree of deflection at high temperatures, the four steel plates are cut evenly along the length direction with the center line of the steel plate width to increase the contact with the furnace roll, especially the center position of the furnace roll. The last 10mm thinner steel plate has the lowest rigidity, so the contact area with the furnace roll is further increased.

[0014] The split steel plates are shot blasted at a speed of 2m / min until the surface quality reaches SA2.0, and then used as furnace plates.

[0015] The first, second, third, and fourth steel plates are sequentially placed on the furnace roller conveyor, with an interval of approximately 500mm between them. This is to increase superheat: the furnace rollers cool down after a steel plate passes over them, and the 500mm steel-free area allows the furnace rollers and any agglomerates to heat up, facilitating a significant cooling of the next steel plate. The first and second slitting plates of the first steel plate are symmetrically arranged along the width of the roller conveyor. Figure 2 As shown, the first and second steel plates are staggered along the width of the roller conveyor to avoid areas that do not contact the roller surface.

[0016] The steel plates are fed into the furnace at a speed of 5 m / min. After the first group exits the furnace, the second group enters the furnace and is placed in a staggered manner according to the relative position of the first group. This cycle is repeated until the fourth group is finished. The furnace temperature is then measured. If the furnace temperature is higher than 500℃, the first to fourth groups are used again in this cycle to continuously pass through the furnace, ensuring that the temperature difference between the plate and the furnace temperature is maximized each time the plates are fed into the furnace.

[0017] When the furnace temperature drops to 500℃ or below after a certain cycle, the difference in shrinkage rate between the furnace roller and the nodule has reached its maximum, and the furnace cycle ends at this point.

[0018] Example 2 like Figure 1 As shown, the specific experimental methods used in the following embodiments are as follows: Four sets of furnace plates were fabricated, each set consisting of four steel plates: the first plate was 81mm thick, the second 54mm thick, the third 27mm thick, and the fourth 9mm thick. The steel plates were used to physically cool the furnace rollers and the nodules. The difference in shrinkage rate during cooling, caused by the material difference between the nodules and the furnace rollers, was used to remove the nodules. At the same time, a suitable thickness gradient of the furnace plates was selected to reduce the impact of different thickness steel plates on the furnace rollers.

[0019] The width of the steel plate is the length of the furnace roll minus 450mm. Since the furnace roll has a certain degree of deflection at high temperatures, the four steel plates are cut evenly along the length direction with the center line of the steel plate width to increase the contact with the furnace roll, especially at the center position of the furnace roll. The last 9mm thinner steel plate has the lowest rigidity, so the contact area with the furnace roll is further increased.

[0020] The split steel plates are shot blasted at a speed of 2m / min until the surface quality reaches SA2.0, and then used as furnace plates.

[0021] The first, second, third, and fourth steel plates are sequentially placed on the furnace roller conveyor, with a 450mm interval between them. This is to increase superheat: the furnace rollers cool down after a steel plate passes over them, and the 450mm unheated area allows the furnace rollers and any agglomerates to heat up, facilitating a significant cooling of the next steel plate. The first and second slitting plates of the first steel plate are symmetrically arranged along the width of the roller conveyor. Figure 2 As shown, the first and second steel plates are staggered along the width of the roller conveyor to avoid areas that do not contact the roller surface.

[0022] The steel plates are fed into the furnace at a speed of 5 m / min. After the first group exits the furnace, the second group enters the furnace and is placed in a staggered manner according to the relative position of the first group. This cycle is repeated until the fourth group is finished. The furnace temperature is then measured. If the furnace temperature is higher than 500℃, the first to fourth groups are used again in this cycle to continuously pass through the furnace, ensuring that the temperature difference between the plate and the furnace temperature is maximized each time the plates are fed into the furnace.

[0023] When the furnace temperature drops to 500℃ or below after a certain cycle, the difference in shrinkage rate between the furnace roller and the nodule has reached its maximum, and the furnace cycle ends at this point.

[0024] Example 3 like Figure 1 As shown, the specific experimental methods used in the following embodiments are as follows: Four sets of furnace plates were fabricated, each set consisting of four steel plates: the first plate was 99mm thick, the second 66mm thick, the third 33mm thick, and the fourth 11mm thick. The steel plates were used to physically cool the furnace rollers and the nodules. The difference in shrinkage rate during cooling, caused by the material difference between the nodules and the furnace rollers, was used to remove the nodules. At the same time, a suitable thickness gradient was selected for the furnace plates to reduce the impact of different thickness steel plates on the furnace rollers.

[0025] The width of the steel plate is the length of the furnace roll minus 550mm. Since the furnace roll has a certain degree of deflection at high temperatures, the four steel plates are cut evenly along the length direction with the center line of the steel plate width to increase the contact with the furnace roll, especially the center position of the furnace roll. The last 11mm thinner steel plate has the lowest rigidity, so the contact area with the furnace roll is further increased.

[0026] The split steel plates are shot blasted at a speed of 2m / min until the surface quality reaches SA2.0, and then used as furnace plates.

[0027] The first, second, third, and fourth steel plates are sequentially placed on the furnace roller conveyor, with an interval of approximately 550mm between them. This is to increase superheat: the furnace rollers cool down after a steel plate passes over them, and the 550mm steel-free area allows the furnace rollers and any agglomerates to heat up, facilitating a significant cooling of the next steel plate. The first and second slitting plates of the first steel plate are symmetrically arranged along the width of the roller conveyor. Figure 2 As shown, the first and second steel plates are staggered along the width of the roller conveyor to avoid areas that do not contact the roller surface.

[0028] The steel plates are fed into the furnace at a speed of 5 m / min. After the first group exits the furnace, the second group enters the furnace and is placed in a staggered manner according to the relative position of the first group. This cycle is repeated until the fourth group is finished. The furnace temperature is then measured. If the furnace temperature is higher than 500℃, the first to fourth groups are used again in this cycle to continuously pass through the furnace, ensuring that the temperature difference between the plate and the furnace temperature is maximized each time the plates are fed into the furnace.

[0029] When the furnace temperature drops to 500℃ or below after a certain cycle, the difference in shrinkage rate between the furnace roller and the nodule has reached its maximum, and the furnace cycle ends at this point.

Claims

1. A method for eliminating furnace roller nodules in a roller hearth heat treatment furnace, characterized in that, Includes the following steps: Step 1: Setting up the furnace passage plates: Four sets of furnace passage plates are made using a heat-resistant material different from the furnace rollers. Each set of furnace passage plates includes four plates of different thicknesses: the first plate is 81-99 mm thick, the second is 54-66 mm thick, the third is 27-33 mm thick, and the fourth is 9-11 mm thick. The width of each plate is the length of the furnace roller minus 450-550 mm, and the length of each plate is 6000-12000 mm. The furnace passage plates are made of carbon steel with a carbon content of 0.25-0.60 wt%. Step 2: Pre-treatment of furnace plates: Each plate is split along its width at the center line to create split plates, and then each split plate is shot blasted; the shot blasting speed is 2m / min; the surface quality of the split plate after the splitting process is SA2.

0. Step 3: Furnace Roller Elimination Process: Arrange the split plates of the first group of furnace-passing plates in descending order of thickness on the furnace front roller conveyor. The split plates of different thicknesses are staggered by 450-550mm before furnace passage. After the first group of furnace-passing plates exits the furnace, arrange the split plates of the second, third, and fourth groups of furnace-passing plates in the same manner as the previous group, staggered relative to the previous group, and then pass them through the furnace in sequence. The furnace roller conveyor speed for the furnace-passing plates during furnace passage is set to 5m / min. Step 4: Temperature detection: After the furnace is circulated through the split plate of the fourth furnace plate, the furnace temperature is detected. If the furnace temperature is greater than 500℃, return to step 3; if the furnace temperature is less than or equal to 500℃, the furnace circulation is ended.

2. The method for eliminating furnace roller nodules in a roller hearth heat treatment furnace according to claim 1, characterized in that, In step three, the split plates of the same width of the furnace plate in each group of furnace plates are symmetrically arranged along the center line of the width direction of the furnace roller track.

3. The method for eliminating furnace roller nodules in a roller hearth heat treatment furnace according to claim 1, characterized in that, In step three, the split plates of the second, third, and fourth groups of furnace plates are misaligned relative to the previous group of furnace plates. This misalignment occurs in the width direction of the furnace roller track.

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