Method for improving grinding precision of backing bearing of twenty-high roll mill

Abstract

The invention provides a method for improving the grinding precision of a backing bearing of a twenty-high rolling mill, which comprises the following steps of: analyzing each size of the backing bearing, finding out a key size which needs to be controlled, fixing a grinding clamp by adopting double tips, controlling the jacking force to be between 1300 and 1400 N, controlling the pressure to be between 34 and 40 Pa, and pressurizing through an expandable sleeve to reduce the bearing clearance to be 0, so that the grinding precision of the backing bearing is improved. The grinding precision is prevented from being influenced by the bearing clearance in the grinding process; during clamping, dial gauges are arranged at the two positions of an upper bus and a side bus of the backing bearing, and the difference of jumping values is controlled within 2 microns by arranging the dial gauges at the two positions, so that the clamping precision is improved; in the grinding process, after the precision is measured according to the grinding roller shape, safety difference grinding is manually adjusted, the backing bearing meeting the high size precision can be efficiently ground, and it is ensured that the repaired backing bearing can meet the requirements for the working performance and the product quality of a rolling mill.

Description

Technical Field

[0001] The invention relates to the technical field of backing bearing repair, in particular to a method for improving the grinding accuracy of a backing bearing of a twenty-high rolling mill. Background Art

[0002] The backing support roller is assembled by the backing bearing, the mandrel and the saddle. As the key component of the twenty-high mill for bearing and transmission, the backing support roller is a high-precision mechanical component. The outer diameter surface of the outer ring of the backing bearing is in direct contact with the middle roller, and it rotates while carrying the rolling force. Therefore, the outer ring not only has sufficient rigidity and fatigue strength through special heat treatment, but also has high-precision fillet processing. The six backing bearings on the same backing support roller are matched according to the wall thickness control. The wall thickness difference between two adjacent bearings is ≤0.002mm, and the wall thickness difference of a single backing support roller is ≤0.006mm, with the middle high and the two sides low. Once the error is too large, the backing bearings of the row of support rollers will be subjected to extremely uneven forces during the rolling process. The outer diameter surface of the outer ring of the backing bearing is in direct contact with the middle roller, and it rotates while carrying the rolling force. In long-term use, due to factors such as wear and fatigue, the bearings are prone to defects such as reduced precision and surface indentations, which will seriously affect the working performance and product quality of the mill. When the backing bearing has the above defects, it is usually removed by grinding the outer ring of the bearing to make its surface reach the required dimensional accuracy before it is put into use. However, the grinding method of the existing technology is difficult to meet the high precision requirements of the backing support roller, and the backing bearing repaired by the existing technology is difficult to guarantee the working performance and product quality of the rolling mill. Summary of the invention

[0003] In order to solve the problem that the backing bearing repaired by the grinding method of the prior art grinder is difficult to meet the high precision requirement of the backing support roller, the present invention proposes a method for improving the grinding precision of the backing bearing of the twenty-high rolling mill.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for improving the grinding accuracy of a twenty-high rolling mill backing bearing comprises the following steps:

[0006] S1, clamping the backing bearing: clamping the backing bearing to be processed on the grinding machine through a grinding fixture, wherein the grinding fixture can make the outer ring of the backing bearing rotate while the inner ring of the bearing is fixed during the grinding process, and the double center of the grinder is used to fix the grinding fixture during clamping, and the bearing clearance is reduced to 0 during clamping;

[0007] S2, edit the grinding process according to the backing bearing size:

[0008] S3, use the edited grinding program to grind the backing bearing on the grinding fixture. In this process, the following method is used to control the machining accuracy, so that the wall thickness difference between two adjacent backing bearings is ≤0.002mm, the roller profile accuracy of a single backing bearing is controlled to ≤0.002mm, the circular runout is ≤0.002㎜, and 25*15mm curved chamfers are added at both ends of the backing bearing:

[0009] Diameter machining accuracy control: For the 6 backing bearings in the backing support roller, first check the wear condition of the backing bearing surface after unloading, grind the backing bearing with the most serious damage first, and grind the remaining 5 backing bearings with the diameter of the first backing bearing being ±0.006mm as the target;

[0010] Control of roller processing accuracy: During the grinding process, the roller accuracy is controlled by repeated measurement and manual adjustment of the installation error value. The adjustment method is as follows: Click "Manual Error" in the grinding program, then click "Installation Error", enter the adjusted error value and press Enter to confirm; the adjusted error value = headstock diameter after grinding - tailstock diameter after grinding + current error value.

[0011] Furthermore, the grinding process includes an outer cylindrical flat roller grinding process and a curve chamfering process. During the grinding process, the outer cylindrical flat roller grinding process is used to grind the outer diameter surface of the backing bearing, and the curve chamfering process is used to machine chamfers at both ends of the backing bearing.

[0012] Furthermore, the outer cylindrical flat roller grinding program includes four processes, namely, process one, process two, process three and process four. The parameters of process one are set as follows: grinding wheel linear speed 20 m / s, headstock speed 14 rpm, pallet speed 800 mm / min, continuous feed 0 mm / min, and periodic feed 0.0030 mm; the parameters of process two are set as follows: grinding wheel linear speed 18 m / s, headstock speed 15 rpm, pallet speed 600 mm / min, and continuous feed 0 mm / min, periodic feed 0.0020 mm; the parameter settings of the process three are: grinding wheel linear speed 16 m / s, headstock speed 15 rpm, support plate speed 400 mm / min, continuous feed 0 mm / min, periodic feed 0.0010 mm; the parameter settings of the process four are: grinding wheel linear speed 14 m / s, headstock speed 16 rpm, support plate speed 300 mm / min, continuous feed 0 mm / min, periodic feed 0.0000 mm.

[0013] Furthermore, the parameters of the curve chamfering program are set as follows: grinding wheel linear speed 22 m / s, headstock speed 24 rpm, pallet speed 200 mm / min, continuous feed 0 mm / min, periodic feed 0.0050 mm, and pallet reversing delay 2 seconds.

[0014] Furthermore, the grinding fixture includes an axle body, an expandable sleeve, two clamping members, a hydraulic connector, an oil pipe and a manual pressure pump. The axle body is provided with an oil inlet channel, one end of the oil inlet channel passes through the outer peripheral wall of the axle body to form an oil inlet port; the expandable sleeve is sleeved on the axle body, and the expandable sleeve is provided with an oil chamber connected to an end of the oil inlet channel away from the oil inlet port; the two clamping members are respectively located at opposite ends of the expandable sleeve and are both sleeved on the axle body, and at least one of the clamping members is detachably connected to the axle body, and each of the clamping members includes a clamp inner disk sleeved on the axle body and a clamp outer disk rotatably wrapped around the outer peripheral surface of the clamp inner disk; one end of the oil pipe is connected to the oil inlet port through the hydraulic connector, and the manual pressure pump is installed on the other end of the oil pipe.

[0015] Furthermore, step S1 includes the following steps:

[0016] S11, removing one of the clamping members from the shaft body, sleeve the backing bearing to be ground on the expandable sleeve, and then installing the removed clamping member on the shaft body, so that the two clamping members are respectively located at opposite ends of the backing bearing to be ground;

[0017] S12, hoisting the grinding fixture equipped with the backing bearing to the grinding machine, and using the double centers of the grinding machine to respectively press the opposite ends of the shaft body, ensuring that the pressing force of the centers on the shaft body is between 1300-1400N;

[0018] S13, connecting one end of the oil pipe to the oil inlet through the oil pressure connector, and setting a micrometer on the upper busbar and the side busbar of the backing bearing respectively;

[0019] S14, connecting a manual hydraulic pump to the other end of the oil pipe, pressurizing the hydraulic oil in the oil chamber by means of the manual hydraulic pump, so as to expand the expandable sleeve, and the expansion of the expandable sleeve drives the inner ring of the backing bearing to expand. In this process, the outer diameter surface of the backing bearing is tapped and rotated so that the inner ring of the bearing expands evenly, thereby reducing the bearing clearance to 0;

[0020] S15, locking the two clamping members in the axial direction so that the centers of the two clamping members coincide with each other, and after locking, the inner plates of the clamps of the two clamping members are respectively clamped at the opposite ends of the inner ring of the backing bearing, and the outer plates of the clamps of the two clamping members are respectively clamped at the opposite ends of the outer ring of the backing bearing;

[0021] S16, connect the outer disk of the fixture and the headstock of the grinder by inserting a rod, then drive the outer disk of the fixture and the outer ring of the backing bearing to rotate through the headstock of the grinder, read the runout values ​​of the micrometer at the upper busbar and the side busbar, and control the value difference between the two places within 2μm.

[0022] Further, in step S16, if the numerical difference between the micrometers at the upper busbar and the side busbar is greater than 2 μm, the clamping piece is adjusted so that the backing bearing can rotate relative to the expandable sleeve, and the backing bearing is rotated to adjust the angle of the backing bearing and then the clamping piece is re-locked until the numerical difference between the two positions is controlled within 2 μm.

[0023] Furthermore, a pressure gauge is installed at the connection between the manual hydraulic pump and the oil pipe to detect the pressure in the oil pipe to ensure that the pressure in the oil pipe is maintained between 34-40Pa during the bearing clearance adjustment process.

[0024] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0025] The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill of the present invention analyzes the dimensions of the backing bearing to find out the key dimensions that need to be controlled. Experiments show that the accuracy of each backing bearing in the backing support roller is extremely important, the wall thickness difference between two adjacent bearings is ≤0.002mm, the roller profile accuracy of a single backing bearing should be controlled to be ≤0.002mm, the circular runout is ≤0.002㎜, and after adding 25*15mm curved chamfers at both ends of the backing bearing, it can better avoid the concentrated load at the end and damage to the middle roller; in order to achieve the grinding accuracy, the method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill of the present invention adopts a double center to fix The grinding fixture is fixed, the top force is controlled between 1300-1400N, the pressure is controlled between 34-40Pa, and the bearing clearance is reduced to 0 by pressurizing with an expandable sleeve to prevent the bearing clearance from affecting the grinding accuracy during the grinding process; when clamping, a micrometer is set at the two positions of the busbar and the side busbar on the backing bearing. The micrometer is set at the two positions to control the runout value difference within 2μm, thereby improving the clamping accuracy; during the grinding process, the manual adjustment of the tolerance grinding according to the grinding roller profile measurement accuracy can efficiently grind out the backing bearing that meets the above-mentioned high dimensional accuracy, ensuring that the repaired backing bearing can meet the working performance and product quality requirements of the rolling mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for improving the grinding accuracy of a backing bearing of a twenty-high rolling mill according to a preferred embodiment of the present invention;

[0027] Figure 2 A structural diagram of a grinding fixture used in a method for improving the grinding accuracy of a backing bearing of a twenty-high rolling mill according to a preferred embodiment of the present invention;

[0028] Figure 3 for Figure 2 Section view along line AA;

[0029] Main component symbols

[0030] 10. Backing bearing; 11. Bearing inner ring; 12. Bearing outer ring; 20. Grinding fixture; 21. Shaft body; 210. Oil inlet channel; 211. Oil inlet; 22. Expandable sleeve; 220. Oil chamber; 23. Clamping piece; 231. Clamp inner disk; 232. Clamp outer disk. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] See also Figures 1 to 3 A preferred embodiment of the present invention provides a method for improving the grinding accuracy of a twenty-high mill backing bearing, comprising the following steps:

[0035] S1, clamping the backing bearing: the backing bearing 10 to be processed is clamped on a grinding machine (not shown) through a grinding fixture 20. The grinding fixture 20 can make the outer ring 12 of the backing bearing 10 rotate while the inner ring 11 of the bearing is fixed during the grinding process. The double center of the grinder (not shown) is used to fix the grinding fixture 20 during clamping, and the bearing clearance is reduced to 0 during clamping.

[0036] In this embodiment, the grinding fixture 20 includes an axle body 21, an expandable sleeve 22, two clamping members 23, a hydraulic connector (not shown), an oil pipe (not shown) and a manual pressure pump (not shown). An oil inlet channel 210 is provided in the axle body 21, and one end of the oil inlet channel 210 passes through the outer peripheral wall of the axle body 21 to form an oil inlet 211. The expandable sleeve 22 is sleeved on the axle body 21, and an oil chamber 220 is provided in the expandable sleeve 22 that is connected to the end of the oil inlet channel 210 away from the oil inlet 211. The two clamping members 23 are respectively located at opposite ends of the expandable sleeve 22 and are both sleeved on the axle body 21, and at least one clamping member 23 is detachably connected to the axle body 21. Each clamping member 23 includes a clamp inner disk 231 sleeved on the axle body 21 and a clamp outer disk 232 rotatably wrapped around the outside of the clamp inner disk 231. Specifically, the inner plate 231 of at least one clamping member 23 is detachably connected to the shaft body 21 through threads. One end of the oil pipe is connected to the oil inlet 211 through a hydraulic connector, and a manual pressure pump is installed at the other end of the oil pipe. The following steps are included when the grinding fixture is used to clamp the backing bearing:

[0037] S11, remove one of the clamping members 23 from the shaft body 21, sleeve the backing bearing 10 to be ground on the expandable sleeve 21, and then install the removed clamping member 23 on the shaft body 21, so that the two clamping members 23 are respectively located at opposite ends of the backing bearing 10 to be ground.

[0038] S12, hoisting the grinding fixture 20 equipped with the backing bearing 10 to the grinding machine, and using the double centers of the grinding machine to respectively press against the opposite ends of the shaft body 21, ensuring that the pressing force of the centers on the shaft body 21 is between 1300-1400N.

[0039] S13, one end of the oil pipe is connected to the oil inlet 211 through the oil pressure connector, and a micrometer (not shown) is respectively set on the upper busbar and the side busbar of the backing bearing 10.

[0040] S14, connect a manual hydraulic pump to the other end of the oil pipe, and use the manual hydraulic pump to pressurize the hydraulic oil in the oil chamber 220 to cause the expandable sleeve 22 to expand. After the expandable sleeve 22 expands, it drives the inner ring 11 of the backing bearing 10 to expand. In this process, the outer diameter surface of the backing bearing 10 is tapped and rotated to make the inner ring 11 of the bearing expand evenly, so that the bearing clearance is reduced to 0, avoiding the clearance from affecting the grinding accuracy of the backing bearing 10.

[0041] In this embodiment, a pressure gauge (not shown) is also installed at the connection between the manual hydraulic pump and the oil pipe to detect the pressure in the oil pipe to ensure that the pressure in the oil pipe is maintained between 34-40Pa during the bearing clearance adjustment process to prevent damage to the expandable sleeve 22.

[0042] S15, locking the two clamping members 23 in the axial direction of the shaft body 21, so as to firmly clamp the backing bearing 10 through the two clamping members 23. Specifically, the two clamping members 23 can be rotated to make the two clamping members 23 approach each other to achieve locking of the backing bearing 10. After locking, the clamp inner disks 231 of the two clamping members 23 are respectively clamped at the opposite ends of the bearing inner ring 11 of the backing bearing 10, and the clamp outer disks 232 of the two clamping members 23 are respectively clamped at the opposite ends of the bearing outer ring 12 of the backing bearing 10.

[0043] S16, connect the clamp outer disk 232 of the clamp 23 and the headstock of the grinder (not shown) through an insert rod (not shown), drive the clamp outer disk 232 and the bearing outer ring 12 of the backing bearing 10 to rotate through the headstock of the grinder, read the runout values ​​of the micrometer at the upper busbar and the side busbar, and control the value difference between the two places within 2μm to complete the clamping. If the value difference of the micrometer at the upper busbar and the side busbar is greater than 2μm, adjust the clamp 23 so that the backing bearing 10 can rotate relative to the expandable sleeve 22, rotate the backing bearing 10 to adjust the bearing angle, and then re-lock the clamp 23 until the value difference between the two places is controlled within 2μm.

[0044] In this embodiment, the plunger is connected to the clamp outer disk 232 of the clamping member 23 away from the oil inlet 211. Specifically, the clamp outer disk 232 and the head frame of the grinder are provided with slots, and the two ends of the plunger are respectively inserted into the slots of the clamp outer disk 232 and the slots on the head frame of the grinder. And because the plunger is connected to the clamp outer disk 232 of the clamping member 23 away from the oil inlet 211, it is possible to prevent the oil pipe from hindering the movement of the plunger during the rotation of the clamp outer disk 232. In addition, the inner diameter surface and side surface of the backing bearing 10 need to be thoroughly cleaned before clamping to prevent impurities from reducing the clamping accuracy.

[0045] S2, edit the grinding process program according to the backing bearing size.

[0046] In this embodiment, the grinding process includes an outer cylindrical flat roller grinding process and a curve chamfering process. During the grinding process, the outer cylindrical flat roller grinding process is used to grind the outer diameter surface of the backing bearing 10, and the curve chamfering process is used to machine chamfers at both ends of the backing bearing 10. Specifically, the outer cylindrical flat roller grinding process includes four processes, namely, process one, process two, process three and process four. The parameters of process one are set as follows: grinding wheel linear speed 20 m / s, headstock speed 14 rpm, support plate speed 800 mm / min, continuous feed 0 mm / min, periodic feed 0.0030 mm; the parameters of process two are set as follows: grinding wheel linear speed 18 m / s, headstock speed 15 rpm, support plate speed 600 mm / min, continuous feed 0 mm / min , cycle feed 0.0020 mm; the parameter settings of process three are: grinding wheel linear speed 16 m / s, headstock speed 15 rpm, support plate speed 400 mm / min, continuous feed 0 mm / min, cycle feed 0.0010 mm; the parameter settings of process four are: grinding wheel linear speed 14 m / s, headstock speed 16 rpm, support plate speed 300 mm / min, continuous feed 0 mm / min, cycle feed 0.0000 mm, see Table 1 for details.

[0047] Table 1

[0048] parameter Process 1 Process 2 Process 3 Process 4 Grinding wheel linear speed (m / s) 20 18 16 14 Headstock speed (rpm) 14 15 15 16 Pallet speed (mm / min) 800 600 400 300 Continuous feed (mm / min) 0.0000 0.0000 0.0000 0.0000 Cycle feed (mm) 0.0030 0.0020 0.0010 0.0000

[0049] In this embodiment, the parameters of the curve chamfering program are set as: grinding wheel linear speed 22 m / s, headstock speed 24 rpm, pallet speed 200 mm / min, continuous feed 0 mm / min, periodic feed 0.0050 mm, pallet reversing delay 2 seconds, see Table 2 for details.

[0050] Table 2

[0051] parameter Process Grinding wheel linear speed (m / s) 22 Headstock speed (rpm) 24 Pallet speed (mm / min) 200 Continuous feed (mm / min) 0.0000 Cycle feed (mm) 0.0050 Pallet reversing delay (seconds) 2

[0052] S3, grinding the backing bearing 10 on the grinding fixture 20 using the edited grinding program, and controlling the machining accuracy using the following method in this process, so that the wall thickness difference between two adjacent backing bearings is ≤0.002mm, the roller profile accuracy of a single backing bearing is controlled to be ≤0.002mm, the circular runout is ≤0.002㎜, and 25*15mm curved chamfers are added at both ends of the backing bearing:

[0053] Diameter machining accuracy control: For the 6 backing bearings 10 in the backing support roller, first check the wear condition of the backing bearing 10 surface after unloading, grind the backing bearing 10 with the most serious damage first, and grind the remaining 5 backing bearings 10 with the diameter of the first backing bearing 10 ± 0.006mm as the target;

[0054] Control of roller processing accuracy: During the grinding process, the roller accuracy is controlled by repeated measurement and manual adjustment of the installation error value. The adjustment method is as follows: Click "Manual Error" in the grinding program, then click "Installation Error", enter the adjusted error value and press Enter to confirm; the adjusted error value = headstock diameter after grinding - tailstock diameter after grinding + current error value.

[0055] For example: the diameter of the headstock after grinding (299.904mm) - the diameter of the tailstock after grinding (299.915mm) + the current error value (0.010mm) = the adjusted safety error value (-0.001mm), then enter the adjusted safety error value -0.001 in the "Installation Error" column and press the Enter key to confirm, click the measurement result interface and press "Y" to continue grinding.

[0056] The method for improving the grinding accuracy of the backing bearing of the twenty-high rolling mill of the present invention analyzes the dimensions of the backing bearing 10 to find out the key dimensions that need to be controlled. Experiments show that the accuracy of each backing bearing 10 in the backing support roller is extremely important, the difference in wall thickness between two adjacent bearings is ≤0.002mm, the roller profile accuracy of a single backing bearing should be controlled to be ≤0.002mm, the circular runout is ≤0.002㎜, and after adding 25*15mm curved chamfers at both ends of the backing bearing, it can better avoid the concentrated load at the end and damage to the middle roller; in order to achieve The grinding precision, the method of improving the grinding precision of the backing bearing of the twenty-roll mill of the present invention, uses a double top to fix the grinding fixture 20, the top force is controlled between 1300-1400N, the pressure is controlled between 34-40Pa, and the bearing clearance is reduced to 0 by pressurizing through the expandable sleeve 22, so as to avoid the bearing clearance affecting the grinding precision during the grinding process; when clamping, a micrometer is set at two positions of the busbar and the side busbar on the backing bearing 10, and the micrometer is set at two positions to control the runout value difference within 2μm, thereby improving the clamping precision. During the grinding process, manually adjusting the tolerance grinding according to the grinding roller type measurement accuracy can efficiently grind out the backing bearing 10 that meets the above-mentioned high dimensional precision, ensuring that the repaired backing bearing 10 can meet the working performance and product quality requirements of the rolling mill.

[0057] In summary, the internal clearance of the bearing can be effectively reduced to 0 by the grinding fixture. Through the cooperation of the double center of the grinder, manual safety adjustment and the grinding fixture, the roller profile accuracy of the backing bearing ≤ 0.002mm and the circular runout ≤ 0.002㎜ can be effectively controlled, providing an accurate guarantee for the matching accuracy of the backing support roller and the dimensional accuracy of the backing bearing itself.

[0058] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for improving the grinding accuracy of a twenty-high rolling mill backing bearing, characterized in that: The following steps are involved: S1, clamping the backing bearing: clamping the backing bearing to be processed on the grinding machine through a grinding fixture, wherein the grinding fixture can make the outer ring of the backing bearing rotate while the inner ring of the bearing is fixed during the grinding process, and the double center of the grinder is used to fix the grinding fixture during clamping, and the bearing clearance is reduced to 0 during clamping; S2, edit the grinding process according to the backing bearing size: S3, use the edited grinding program to grind the backing bearing on the grinding fixture. In this process, the following method is used to control the machining accuracy, so that the wall thickness difference between two adjacent backing bearings is ≤0.002mm, the roller profile accuracy of a single backing bearing is controlled to ≤0.002mm, the circular runout is ≤0.002㎜, and 25*15mm curved chamfers are added at both ends of the backing bearing: Diameter machining accuracy control: For the 6 backing bearings in the backing support roller, first check the wear condition of the backing bearing surface after unloading, grind the backing bearing with the most serious damage first, and grind the remaining 5 backing bearings with the diameter of the first backing bearing being ±0.006mm as the target; Control of roller processing accuracy: During the grinding process, the roller accuracy is controlled by repeated measurement and manual adjustment of the installation error value. The adjustment method is as follows: click "Manual error" in the grinding program, then click "Installation error", enter the adjusted error value and press Enter to confirm; the adjusted error value = headstock diameter after grinding - tailstock diameter after grinding + current error value.

2. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 1, characterized in that: The grinding process includes an outer cylindrical flat roller grinding process and a curve chamfering process. During the grinding process, the outer cylindrical flat roller grinding process is used to grind the outer diameter surface of the backing bearing, and the curve chamfering process is used to machine chamfers at both ends of the backing bearing.

3. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 2, characterized in that: The cylindrical flat roller grinding program includes four processes, namely, process one, process two, process three and process four. The parameters of process one are set as follows: grinding wheel linear speed of 20 m / s, headstock speed of 14 rpm, pallet speed of 800 mm / min, continuous feed of 0 mm / min, and periodic feed of 0.0030 mm; the parameters of process two are set as follows: grinding wheel linear speed of 18 m / s, headstock speed of 15 rpm, pallet speed of 600 mm / min, continuous feed of 0 mm / min, and periodic feed of 0.0020 mm; the parameters of process three are set as follows: grinding wheel linear speed of 16 m / s, headstock speed of 15 rpm, pallet speed of 400 mm / min, continuous feed of 0 mm / min, and periodic feed of 0.0010 mm; the parameters of process four are set as follows: grinding wheel linear speed of 14 m / s, headstock speed of 16 rpm, pallet speed of 300 mm / min, continuous feed of 0 mm / min, and periodic feed of 0.0000 mm.

4. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 2, characterized in that: The parameters of the curve chamfering program are set as follows: grinding wheel linear speed 22 m / s, headstock speed 24 rpm, pallet speed 200 mm / min, continuous feed 0 mm / min, periodic feed 0.0050 mm, and pallet reversing delay 2 seconds.

5. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 1, characterized in that: The grinding fixture includes an axle body, an expandable sleeve, two clamping members, a hydraulic connector, an oil pipe and a manual pressure pump. The axle body is provided with an oil inlet channel, one end of which passes through the outer wall of the axle body to form an oil inlet; the expandable sleeve is sleeved on the axle body, and the expandable sleeve is provided with an oil chamber connected to an end of the oil inlet channel away from the oil inlet; the two clamping members are respectively located at opposite ends of the expandable sleeve and are both sleeved on the axle body, and at least one of the clamping members is detachably connected to the axle body, and each of the clamping members includes a clamp inner disk sleeved on the axle body and a clamp outer disk rotatably wrapped around the outer circumference of the clamp inner disk; one end of the oil pipe is connected to the oil inlet through the hydraulic connector, and the manual pressure pump is installed on the other end of the oil pipe.

6. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 5, characterized in that: Step S1 includes the following steps: S11, removing one of the clamping members from the shaft body, sleeve the backing bearing to be ground on the expandable sleeve, and then installing the removed clamping member on the shaft body, so that the two clamping members are respectively located at opposite ends of the backing bearing to be ground; S12, hoisting the grinding fixture equipped with the backing bearing to the grinding machine, and using the double centers of the grinding machine to respectively press the opposite ends of the shaft body, ensuring that the pressing force of the centers on the shaft body is between 1300-1400N; S13, connecting one end of the oil pipe to the oil inlet through the oil pressure connector, and setting a micrometer on the upper busbar and the side busbar of the backing bearing respectively; S14, connecting a manual hydraulic pump to the other end of the oil pipe, pressurizing the hydraulic oil in the oil chamber by means of the manual hydraulic pump, so as to expand the expandable sleeve, and the expansion of the expandable sleeve drives the inner ring of the backing bearing to expand. In this process, the outer diameter surface of the backing bearing is tapped and rotated so that the inner ring of the bearing expands evenly, thereby reducing the bearing clearance to 0; S15, locking the two clamping members in the axial direction so that the centers of the two clamping members coincide with each other, and after locking, the inner plates of the clamps of the two clamping members are respectively clamped at the opposite ends of the inner ring of the backing bearing, and the outer plates of the clamps of the two clamping members are respectively clamped at the opposite ends of the outer ring of the backing bearing; S16, connect the outer disk of the fixture and the headstock of the grinder by inserting a rod, then drive the outer disk of the fixture and the outer ring of the backing bearing to rotate through the headstock of the grinder, read the runout values ​​of the micrometer at the upper busbar and the side busbar, and control the value difference between the two places within 2μm.

7. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 6, characterized in that: In step S16, if the numerical difference between the micrometers at the upper busbar and the side busbar is greater than 2 μm, the clamp is adjusted so that the backing bearing can rotate relative to the expandable sleeve. The backing bearing is rotated to adjust the angle of the backing bearing and then the clamp is re-locked until the numerical difference between the two locations is controlled within 2 μm.

8. The method for improving the grinding accuracy of the backing bearing of a twenty-high rolling mill according to claim 6, characterized in that: A pressure gauge is also installed at the connection between the manual hydraulic pump and the oil pipe to detect the pressure in the oil pipe to ensure that the pressure in the oil pipe is maintained between 34-40Pa during the bearing clearance adjustment process.

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