Precision Repair Method for Large Support Rollers of Rolling Mill

Abstract

The present invention discloses a method for precision repairing large support rollers for a rolling mill. The method comprises the following steps: analyzing and confirming the accuracy of key dimensions of the support roller to be repaired; replacing worn bearing seat rings, heating and installing new rings to ensure an interference fit, and measuring the grinding amount; making a babbitt alloy support shoe, calibrating the support roller installation accuracy, and ensuring coaxiality; covering the contact surface between the grinding wheel and the roller with clean grinding fluid; polishing the roller neck to ensure a burr-free surface; hoisting a standard support roller, calibrating the center of the grinding machine, calculating the bearing seat repair dimensions, and performing an idle run; grinding the bearing seat to ensure that the dimensions, circular runout, coaxiality, and roughness meet the standards; replacing the support shoe, calibrating the grinding machine, and then calculating the roller body repair dimensions and performing an idle run; grinding the roller body using the repaired bearing seat as a reference to ensure that the coaxiality and circular runout meet the standards; and inspecting the overall dimensions using the grinding machine's measurement function. The present invention solves the problem that existing methods for precision repairing large support rollers for rolling mills cannot meet the required support roller accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of repairing rolling mill support rollers, in particular to a precision repairing method for large-scale support rollers of a rolling mill. Background Art

[0002] Backup rolls are crucial components in rolling mills. Their primary function is to support the work rolls and intermediate rolls, preventing them from bending and deforming, which could affect strip quality. Backup roll accuracy encompasses coaxiality, cylindricity (also known as circular runout), and roll profile accuracy. As customers increasingly demand increasingly stringent requirements for strip surface quality and profile accuracy, backup roll accuracy has become crucial. This accuracy directly impacts the running accuracy of the work and intermediate rolls, and maintaining this running accuracy, in turn, determines the surface quality and profile accuracy of the final product. Furthermore, backup roll accuracy is directly related to roll-changing cycles, bearing life, and mill production efficiency.

[0003] The precision of backup rollers primarily includes: roller body coaxiality, cylindricity (circular runout), roller profile accuracy, and the required roughness standard of less than Ra0.2μm for the bearing seat. Backup rollers typically weigh over 20 tons, are generally larger than 1.2 meters in diameter, and are generally longer than 4 meters. Currently, conventional backup roller precision repair and production processing methods rely primarily on lathing followed by grinding, supplemented by polishing repair. However, this repair method cannot guarantee the required bearing seat roughness of less than Ra0.2μm and precise circular runout. Furthermore, measurement methods primarily rely on manual operation, which often leads to large measurement errors. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for precision repairing large support rollers of a rolling mill, which can solve the problem that the existing method for precision repairing large support rollers of a rolling mill cannot ensure the precision requirements of the support rollers.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is: the precision repair method of large-scale support rollers of a rolling mill comprises the following steps:

[0006] S1. Analyze the key dimensions of the support roller to be repaired and confirm the accuracy of the key dimensions. The key dimensions include the coaxiality, roughness, and roundness of the bearings at both ends, as well as the coaxiality between the roller body and the roller neck at the bearings at both ends.

[0007] S2. Replace the worn bearing ring, turn the support roller bearing seat, heat the new bearing ring with a ring heater, and install the heated new ring on the turned bearing seat; after cooling, the new ring will have an interference fit with the bearing seat, and the amount of grinding required will be measured;

[0008] S3. Make the support shoe according to the size of the grinder center frame and roll neck. The contact area between the support shoe and the support roller is made of babbitt alloy. By adjusting the height of the grinder center frame and the support shoe, calibrate the installation accuracy of the support roller to ensure that the installation accuracy is less than 0.0025mm and the coaxiality of the roller body and the bearing seat is guaranteed.

[0009] S4. Use clean grinding fluid to spray and ensure that the grinding fluid can cover the contact surface between the grinding wheel and the roller;

[0010] S5. Polish the roller neck of the support roller to ensure that the surface is clean and free of burrs;

[0011] S6. Hoist the standard support roller to the grinder, adjust the center frame position of the grinder according to the support position of the support roller, use a dial indicator to adjust the installation center of the standard support roller and the center position of the grinder to ensure that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004 mm, and lock the support bearing after adjustment; calculate the bearing seat repair size based on the removal amount measured in step S2, and perform dry run on the grinder based on the bearing seat repair size; after completion, hoist the standard support roller off the grinder;

[0012] S7. Hoist the support roller to be repaired to the grinding machine, start the grinding machine, and grind the bearing seats at both ends of the support roller to ensure that the bearing seat size, circular runout, coaxiality, and surface roughness of the support roller meet the acceptance standards; after completion, hoist the support roller away from the grinding machine;

[0013] S8. After the bearing position is repaired, the support shoe is replaced and the standard support roller is hoisted onto the grinder again. The position of the center frame of the grinder is adjusted according to the support position of the support roller. The installation center of the standard support roller and the center position of the grinder are adjusted using a dial indicator to ensure that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004 mm. After adjustment, the support shoe is locked. The repair size of the roller body is calculated based on the removal amount measured in step S2, and an idle run is performed on the grinder based on the repair size of the roller body. After completion, the standard support roller is hoisted off the grinder.

[0014] S9. Hoist the support roller with the repaired bearing seat to the grinder, start the grinder, and use the repaired bearing seat as a reference to grind the roller body to ensure that the coaxiality and circular runout of the entire roller meet the acceptance standards;

[0015] S10. After grinding is completed, use the measuring function of the grinder to inspect the overall size of the support roller.

[0016] In the technical solution of the above-mentioned method for precision repairing large-scale support rolls of a rolling mill, a more specific technical solution may also be: the heating temperature in step S2 is 120-150°C.

[0017] In some possible implementation schemes, the interference fit in step S2 is 0.3-0.4 mm.

[0018] In some possible implementations, the grinding wheel is chamfered before grinding.

[0019] In some possible implementation schemes, the grinding wheel is made of SN abrasive and has an abrasive grain size of 120 grains.

[0020] In some possible implementation schemes, the rotating contact surfaces of the support shoe and the support roller are lubricated by dripping oil.

[0021] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0022] 1. The present invention uses the roll neck of the roll itself as a reference, positions the roll necks at both ends of the roll, and uses the roll necks at both ends as support positions for bearing grinding, thereby fully utilizing the high precision and high efficiency of the grinding machine to grind the required dimensional accuracy and roughness of the bearings at both ends; since the roller body repair requires a relatively large amount of grinding and the support roller is heavy, after the bearing repair is completed, the repaired support roller bearing is combined with the large support pad for support to stably grind the entire support roller body, thereby repairing the roll to a support roller that meets the precision requirements.

[0023] 2. This method uses the roll neck itself as the grinding reference, positioning the roll neck at both ends to ensure the stability and accuracy of the support position of the roll neck at both ends during grinding. This method avoids the machining errors caused by improper reference selection in traditional methods and improves the repair accuracy of the backup roll.

[0024] 3. By taking advantage of the grinding machine, the present invention can accurately grind the dimensional accuracy and roughness of the bearing positions at both ends to ensure that the required accuracy requirements are met, which not only improves the processing efficiency, but also significantly improves the performance and life of the support roller.

[0025] 4. The repaired support roller bearings and large support pads are used as supports to effectively solve the stability and support problems during the grinding process.

[0026] 5. The contact position between the support pad and the support roller is made of Babbitt alloy to avoid wear of the support position when the roller is repaired; the rotating contact surface between the support pad and the support roller is drip-lubricated to effectively prevent heating caused by rotation friction.

[0027] 6. Improve the cleanliness of the grinding fluid, spray the fluid to cover the contact surface between the grinding wheel and the support roller, and chamfer the grinding wheel in advance to better control the surface quality of the repair position.

[0028] 7. The selection of grinding wheel material and particle size can effectively ensure the grinding accuracy of the roughness of the support shaft bearing seat. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments:

[0030] The precision requirements for the large support rollers of the rolling mill that need to be repaired in this embodiment are that the coaxiality of the bearing ends is 0.005 mm, the roughness is less than Ra0.2 μm, the roundness is 0.008 mm, and the coaxiality of the roller body and the roller neck of the bearing ends is 0.005 mm. The repair method for the worn support roller includes the following steps:

[0031] S1. Analyze the key dimensions of the support roller to be repaired and confirm the accuracy of the key dimensions. The key dimensions include the coaxiality, roughness, and roundness of the bearings at both ends, as well as the coaxiality between the roller body and the roller neck at both ends. Ensure that the accuracy requirements are clear before repair to provide an accurate benchmark for subsequent repairs.

[0032] S2. Replace the worn bearing ring, turn the support roller bearing seat, and use a ring heater to heat the new bearing ring at a temperature of 120-150°C to prevent the ring from deforming or being loosely installed due to excessively high or low temperatures. Install the heated new ring onto the turned bearing seat. After cooling, the new ring has an interference fit with the bearing seat of 0.3-0.4mm. Measure the amount of grinding required. This step ensures the dimensional accuracy and fit strength of the bearing seat, not only repairing the function of the bearing seat but also extending the service life of the support roller.

[0033] S3. The support pad is manufactured according to the dimensions of the grinder center frame and the roll neck. To prevent wear on the roll neck, the contact area between the support pad and the support roll is made of babbitt alloy. Oil is dripped onto the contact area between the support pad and the support roll to reduce friction and prevent damage to the roll neck due to frictional overheating during the repair process. The installation accuracy of the support roll is calibrated by adjusting the height of the grinder center frame and the support pad to ensure an installation accuracy of less than 0.0025mm. This high-precision calibration ensures that the coaxiality between the roll body and the roll neck at both ends of the bearing is 0.005mm during the repair process, thereby improving the overall accuracy after the repair.

[0034] S4. Improve the cleanliness of the grinding fluid system of the grinding machine, adjust the grinding fluid injection angle, and spray the grinding fluid on the grinding wheel while taking into account the contact surface between the grinding wheel and the roller. Use clean grinding fluid to spray and ensure that the grinding fluid can cover the contact surface between the grinding wheel and the roller to prevent the grinding wheel from threshing and scratching the roller surface during the repair process; chamfer the grinding wheel before grinding. The grinding wheel material is SN abrasive and the abrasive grit size is 120 grains.

[0035] S5. Use sandpaper to polish the roller necks at both ends of the support roller to ensure that the surfaces of the roller necks at both ends are clean and free of burrs.

[0036] S6. Hoist the standard support roller to the grinder, adjust the center frame position of the grinder according to the support position of the support roller, use a dial indicator to adjust the installation center of the standard support roller and the center position of the grinder to ensure that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004 mm, and lock the support bearing after adjustment; calculate the bearing seat repair size based on the removal amount measured in step S2, and perform dry run on the grinder based on the bearing seat repair size; after completion, hoist the standard support roller off the grinder;

[0037] S7. Hoist the support roller to be repaired to the grinding machine, start the grinding machine, and grind the bearing seats at both ends of the support roller to ensure that the bearing seat size, circular runout, coaxiality, and surface roughness of the support roller meet the factory acceptance standards; after completion, hoist the support roller away from the grinding machine;

[0038] S8. After the bearing position is repaired, the support shoe is replaced and the standard support roller is hoisted onto the grinder again. The position of the center frame of the grinder is adjusted according to the support position of the support roller. The installation center of the standard support roller and the center position of the grinder are adjusted using a dial indicator to ensure that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004 mm. After adjustment, the support shoe is locked. The repair size of the roller body is calculated based on the removal amount measured in step S2, and an idle run is performed on the grinder based on the repair size of the roller body. After completion, the standard support roller is hoisted off the grinder.

[0039] S9. Hoist the support roller with the repaired bearing seat to the grinder, start the grinder, and use the repaired bearing seat as a reference to grind the roller body to ensure that the coaxiality and circular runout of the entire roller meet the acceptance standards;

[0040] S10. After grinding is completed, use the measuring function of the grinder to inspect the overall size of the support roller.

[0041] The large support rollers of the rolling mill repaired according to the above method can ensure that the coaxiality, roughness, roundness of both ends of the bearing position and the coaxiality of the roller body and the roller neck of the bearing position meet high precision requirements, which can extend the service life of the support rollers, reduce the frequency of replacement of support rollers, and reduce equipment maintenance costs; it can also improve the repair efficiency and quality, reduce errors and scratches during the repair process, reduce material waste, and reduce repair costs.

[0042] The above embodiments are intended to illustrate the core concepts and principles of the present invention, rather than to strictly limit them. Any adjustments or modifications implemented in accordance with the spirit of the present invention and within the scope of protection defined by the claims shall be deemed to fall within the scope of protection of the present invention.

Claims

1. A method for precision repair of large support rollers of a rolling mill, characterized in that The following steps are involved: S1. Analyze the key dimensions of the support roller to be repaired and confirm the accuracy of the key dimensions. The key dimensions include the coaxiality, roughness, and roundness of the bearings at both ends, as well as the coaxiality between the roller body and the roller neck at the bearings at both ends. S2. Replace the worn bearing ring, turn the support roller bearing seat, heat the new bearing ring with a ring heater, and install the heated new ring on the turned bearing seat; after cooling, the new ring will have an interference fit with the bearing seat, and the amount of grinding required will be measured; S3. Make the support shoe according to the size of the grinder center frame and roll neck. The contact area between the support shoe and the support roller is made of babbitt alloy. By adjusting the height of the grinder center frame and the support shoe, calibrate the installation accuracy of the support roller to ensure that the installation accuracy is less than 0.0025mm and the coaxiality of the roller body and the bearing seat is guaranteed. S4. Use clean grinding fluid to spray and ensure that the grinding fluid can cover the contact surface between the grinding wheel and the roller; S5. Polish the roller neck of the support roller to ensure that the surface is clean and free of burrs; S6. Hoist the standard support roller to the grinder, adjust the center frame position of the grinder according to the support position of the support roller, use a dial indicator to adjust the installation center of the standard support roller and the center position of the grinder to ensure that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004 mm, and lock the support bearing after adjustment; calculate the bearing seat repair size based on the removal amount measured in step S2, and perform dry run on the grinder based on the bearing seat repair size; after completion, hoist the standard support roller off the grinder; S7. Hoist the support roller to be repaired to the grinding machine, start the grinding machine, and grind the bearing seats at both ends of the support roller to ensure that the bearing seat size, circular runout, coaxiality, and surface roughness of the support roller meet the acceptance standards; after completion, hoist the support roller away from the grinding machine; S8. After the bearing seat repair is completed, the support shoe is replaced, and the standard support roller is hoisted onto the grinder again. The position of the grinder center frame is adjusted, and the deviation between the center of the standard support roller and the center of the grinder is calibrated to ensure that the deviation is less than 0.004 mm. After adjustment, the support shoe is locked. The repaired dimensions of the roller body are calculated based on the removal amount measured in step S2, and a dry run is performed on the grinder based on the repaired dimensions of the roller body. After completion, the standard support roller is hoisted off the grinder. S9. Hoist the support roller with the repaired bearing seat to the grinder, start the grinder, and use the repaired bearing seat as a reference to grind the roller body to ensure that the coaxiality and circular runout of the entire roller meet the acceptance standards; S10. After grinding is completed, use the measuring function of the grinder to inspect the overall size of the support roller.

2. The method for precision repairing large-scale support rollers of a rolling mill according to claim 1, characterized in that: The heating temperature in step S2 is 120-150°C.

3. The method for precision repairing large-scale support rollers of a rolling mill according to claim 2, characterized in that: The interference fit in step S2 is 0.3-0.4 mm.

4. The method for precision repairing large-scale support rolls of a rolling mill according to any one of claims 1 to 3, characterized in that: Chamfer the grinding wheel before grinding.

5. The method for precision repairing large-scale support rollers of a rolling mill according to claim 4, characterized in that: The grinding wheel is made of SN abrasive and has a grit size of 120.

6. The method for precision repairing large-scale support rollers of a rolling mill according to claim 1, characterized in that: The rotating contact surfaces of the support roller and the supporting roller are lubricated with drip oil.