Precision repairing method for large supporting roll of rolling mill

Abstract

The invention discloses a method for repairing the precision of a large supporting roller of a rolling mill. The method comprises the following steps: analyzing and confirming the precision of the key size of the supporting roller to be repaired; a worn bearing position ferrule is replaced, a new ferrule is heated and installed, interference fit is ensured, and the grinding amount is measured; manufacturing a babbitt metal supporting tile, calibrating the mounting precision of the supporting roller, and ensuring the coaxiality; the contact surface of the grinding wheel and the roller is covered with clean grinding fluid; polishing the roll neck to ensure that the surface is burr-free; hoisting a standard back-up roll to calibrate the center of the grinding machine, calculating the repair size of a bearing position and performing idle running; the bearing position is ground, and it is ensured that the size, circle run-out, coaxiality and roughness reach the standard; replacing a supporting tile, calibrating a grinding machine, calculating a roller body repairing size, and carrying out idle running; grinding the roller body by taking the repaired bearing position as a reference to ensure that the coaxiality and the circular run-out reach the standard; and checking and accepting the overall size by using a grinder measuring function. The problem that an existing rolling mill large supporting roller precision repairing method cannot meet the supporting roller precision requirement is solved.

Description

Technical Field

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

[0002] The backup roll is an important part of the rolling mill. Its main function is to support the working roll or the intermediate roll to prevent the working roll from bending and deforming, which would affect the quality of the strip. The accuracy of the backup roll includes coaxiality, cylindricity (also known as circular runout), roll shape accuracy, etc. As customers have increasingly stringent requirements on the surface quality and plate shape accuracy of strip products, the accuracy of the backup roll has become crucial because it directly affects the running accuracy of the working roll and the intermediate roll. The maintenance of this running accuracy further determines the surface quality and plate shape accuracy of the final product. In addition, the accuracy of the backup roll is also directly related to the length of the roll replacement cycle, the service life of the bearings, and the production efficiency of the rolling mill.

[0003] The precision of the support roller mainly includes: roller body coaxiality, cylindricity (circular runout), roller shape accuracy, and the roughness standard of the bearing position that must be less than Ra0.2μm. The weight of the support roller is basically more than 20 tons, the diameter is generally more than 1.2 meters, and the length is generally more than 4 meters. At present, the conventional support roller precision repair and production and processing methods mainly rely on lathe turning and grinding, supplemented by grinding repair. However, this repair method cannot guarantee the requirements of the bearing position roughness less than Ra0.2μm and accurate circular runout. At the same time, in terms of measurement methods, it mainly relies 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: 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 of the bearings at both ends; S2. Replace the worn bearing seat ring, turn the support roller bearing seat, use the ring heater to heat the new bearing seat ring, and install the heated new ring on the turned bearing seat; the cooled new ring is interference fit with the bearing seat, and the amount of grinding removal is measured; S3. The support bearing is made according to the size of the grinder center frame and the roll neck. The contact position between the support bearing and the support roll is made of babbitt alloy. The installation accuracy of the support roll is calibrated by adjusting the height of the grinder center frame and the support bearing to ensure that the installation accuracy is less than 0.0025mm and the coaxiality between the roll body and the bearing position 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, hoisting the standard support roller to the grinder, adjusting the position of the center frame of the grinder according to the support position of the support roller, using a micrometer to adjust the installation center of the standard support roller and the center position of the grinder, ensuring that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004mm, and locking the support bearing after adjustment; calculating the bearing seat repair size according to the removal amount measured in step S2, and performing dry run on the grinder according to the bearing seat repair size; after completion, hoisting the standard support roller away from the grinder; S7. Hoist the support roller to be repaired to the grinder, start the grinder, grind the bearings at both ends of the support roller, and ensure that the bearing size, circular runout, coaxiality, and surface roughness of the support roller meet the acceptance standards; after completion, hoist the support roller away from the grinder; S8. After the bearing position is repaired, the support bearing is replaced, and the standard support roller is hoisted to 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 micrometer 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 bearing is locked; according to the removal amount measured in step S2, the repair size of the roller body is calculated, and the roller body is run dry on the grinder according to the repair size of the roller body; after completion, the standard support roller is hoisted away from the grinder; S9. Hoist the support roller with the repaired bearing position to the grinder, start the grinder, use the repaired bearing position as a reference, grind the roller body, and 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.

[0006] 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.

[0007] In some possible implementation schemes, the interference fit in step S2 is 0.3-0.4 mm.

[0008] In some possible implementations, the grinding wheel is chamfered before grinding.

[0009] In some possible implementation schemes, the grinding wheel is made of SN abrasive and has an abrasive grain size of 120 grains.

[0010] In some possible implementation schemes, the rotating contact surfaces between the support shoe and the support roller are drip-lubricated.

[0011] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 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 grinding the bearing positions, thereby fully utilizing the advantages of high precision and high efficiency of grinding by the grinder to grind the required dimensional accuracy and roughness of the bearing positions at both ends; since the roller body repair requires a relatively large amount of grinding and the support roller is heavy, after the bearing position repair is completed, the repaired support roller bearing position is combined with a large support shoe for support to stably grind the entire support roller body, thereby repairing the roll to a support roller that meets the accuracy requirements.

[0012] 2. The present invention uses the roll neck of the roll itself as the reference for grinding, and positions the two ends of the roll neck to ensure the stability and accuracy of the support position of the two ends of the roll neck as the bearing position for grinding. This method avoids the processing error caused by improper reference selection in the traditional method and improves the repair accuracy of the support roll.

[0013] 3. By utilizing the advantages of grinding by a grinder, 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 rollers.

[0014] 4. The repaired support roller bearings and large support bearings are used as supports, which effectively solves the stability and support problems during the grinding process.

[0015] 5. The contact position between the support bearing 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 bearing and the support roller is drip-lubricated to effectively prevent heating caused by rotation friction.

[0016] 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.

[0017] 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

[0018] The present invention will be further described below in conjunction with embodiments: The precision requirements of the large support rollers of the rolling mill to be repaired in this embodiment are that the coaxiality of the two ends of the bearing position 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 position at both ends is 0.005 mm. The repair method of the worn support roller includes the following steps: S1. Analyze the key dimensions of the support roller to be repaired and confirm the accuracy of the key dimensions, including 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; ensure that the accuracy requirements before repair are clear, and provide an accurate benchmark for subsequent repairs; S2. Replace the worn bearing seat ring, turn the support roller bearing seat, use a ring heater to heat the new bearing seat ring, the heating temperature is 120-150°C, to avoid deformation of the ring or loose installation due to too high or too low temperature; install the heated new ring on the turned bearing seat, the cooled new ring and the bearing seat have an interference fit, the interference amount is 0.3-0.4mm, and the amount to be removed by grinding is measured; this step ensures the dimensional accuracy and fit strength of the bearing seat, not only repairs the function of the bearing seat, but also extends the service life of the support roller; S3. The support bearing is made according to the size of the grinder center frame and the roll neck. In order to prevent the roll neck from being worn, the contact position between the support bearing and the support roll is made of Babbitt alloy. Oil is dripped at the contact position between the support bearing and the support roll to reduce friction and prevent the roll neck from being damaged due to friction 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 bearing to ensure that the installation accuracy is less than 0.0025mm. This high-precision calibration ensures that the coaxiality of the roll body and the roll neck at the bearing positions at both ends is 0.005mm during the repair process, thereby improving the overall accuracy after repair. S4. Improve the cleanliness of the grinding fluid system of the grinder, adjust the spray angle of the grinding fluid, spray the grinding fluid on the grinding wheel, and take into account the contact surface between the grinding wheel and the roller. Use clean grinding fluid to spray, ensure that the grinding fluid can cover the contact surface between the grinding wheel and the roller, and prevent the grinding wheel from threshing and scratching the roller surface during the repair process; chamfer the grinding wheel before grinding, and the grinding wheel material is SN abrasive, and the abrasive grain size is 120 grains; S5. Polish the roller necks at both ends of the support roller with sandpaper to ensure that the surfaces of the roller necks at both ends are clean and free of burrs. S6, hoisting the standard support roller to the grinder, adjusting the position of the center frame of the grinder according to the support position of the support roller, using a micrometer to adjust the installation center of the standard support roller and the center position of the grinder, ensuring that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004mm, and locking the support bearing after adjustment; calculating the bearing seat repair size according to the removal amount measured in step S2, and performing dry run on the grinder according to the bearing seat repair size; after completion, hoisting the standard support roller away from the grinder; S7. Hoist the support roller to be repaired to the grinder, start the grinder, grind the bearings at both ends of the support roller, and ensure that the bearing 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 grinder; S8. After the bearing position is repaired, the support bearing is replaced, and the standard support roller is hoisted to 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 micrometer 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 bearing is locked; according to the removal amount measured in step S2, the repair size of the roller body is calculated, and the roller body is run dry on the grinder according to the repair size of the roller body; after completion, the standard support roller is hoisted away from the grinder; S9. Hoist the support roller with the repaired bearing position to the grinder, start the grinder, use the repaired bearing position as a reference, grind the roller body, and 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.

[0019] 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.

[0020] The above embodiments are intended to illustrate the core concepts and principles of the present invention, rather than to strictly limit them. Within the spirit of the present invention and the scope of protection defined by the claims, any form of adjustment or change implemented by the present invention shall be deemed to fall within the scope of protection of the present invention.

Claims

1. A method for precision repair of large support rolls 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 of the bearings at both ends; S2. Replace the worn bearing seat ring, turn the support roller bearing seat, use the ring heater to heat the new bearing seat ring, and install the heated new ring on the turned bearing seat; the cooled new ring is interference fit with the bearing seat, and the amount of grinding removal is measured; S3. The support bearing is made according to the size of the grinder center frame and the roll neck. The contact position between the support bearing and the support roll is made of babbitt alloy. The installation accuracy of the support roll is calibrated by adjusting the height of the grinder center frame and the support bearing to ensure that the installation accuracy is less than 0.0025mm and the coaxiality between the roll body and the bearing position 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, hoisting the standard support roller to the grinder, adjusting the position of the center frame of the grinder according to the support position of the support roller, using a micrometer to adjust the installation center of the standard support roller and the center position of the grinder, ensuring that the deviation between the center of the standard support roller and the center of the grinder is less than 0.004mm, and locking the support bearing after adjustment; calculating the bearing seat repair size according to the removal amount measured in step S2, and performing dry run on the grinder according to the bearing seat repair size; after completion, hoisting the standard support roller away from the grinder; S7. Hoist the support roller to be repaired to the grinder, start the grinder, grind the bearings at both ends of the support roller, and ensure that the bearing size, circular runout, coaxiality, and surface roughness of the support roller meet the acceptance standards; after completion, hoist the support roller away from the grinder; S8. After the bearing position is repaired, the support bearing is replaced, and the standard support roller is hoisted to the grinder again. The position of the center frame of the grinder 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 bearing is locked; according to the removal amount measured in step S2, the repair size of the roller body is calculated, and the roller body is run dry on the grinder according to the repair size of the roller body; after completion, the standard support roller is hoisted away from the grinder; S9. Hoist the support roller with the repaired bearing position to the grinder, start the grinder, use the repaired bearing position as a reference, grind the roller body, and 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 support rollers of a rolling mill according to claim 1, characterized in that: The heating temperature in step S2 is 120 to 150°C.

3. The method for precision repairing large 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 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 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 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 by dripping oil.