A grinding process and detection method for removing spiral marks on a roll

Abstract

The present application relates to a kind of grinding processes for removing roll spiral, including rough grinding, semi-finish grinding, finish grinding, after rough grinding process, wheel shape dressing is carried out, two sides of grinding wheel are dressed as transition arc type according to dressing curve, and the dressing curve is established according to the following rules: selecting the center of circle on the straight line 10mm from the side of grinding wheel, the distance from the center of circle to the end of grinding wheel is radius, selecting the circle with radius 100mm-500mm as arc curve, as the transition arc of left and right sides, connecting the tangent of two circles with transition arc, to obtain dressing curve.The present application can effectively remove the spiral on the surface of grinding roll, effectively control the surface quality of roll grinding, and finally improve the surface quality of rolled plate.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, and in particular relates to a grinding process and testing method for removing spiral marks from rolling mill rolls. Background Technology

[0002] Spiral marks often appear during the grinding process of rolling mill rolls, especially on rolls with convex surfaces. Rolls used in rolling automotive panels have high requirements; the rolls coming off the mill must be polished with an oilstone and inspected to ensure no spiral marks are present.

[0003] There are many reasons for the formation of spiral marks in roll grinding. It is related to the characteristics of the grinding wheel, process parameters, grinding wheel dressing quality, machine tool precision and rigidity, etc.

[0004] To address the issue of spiral marks appearing during roll grinding, certain control measures were implemented, as shown in Table 1.

[0005] Table 1. Existing Techniques for Controlling Spiral Marking in Roll Grinding

[0006]

[0007] Through practical exploration, it was found that by modifying grinding parameters and controlling the grinding method, the appearance of spiral marks could be eliminated, but it was not stable enough. Even when using the same program, spiral marks would still frequently appear on the rollers. Observation and analysis revealed that the appearance of uncontrollable spiral marks was caused by the sharp right angles on both sides of the grinding wheel.

[0008] The existing technology "Control of Spiral Marks on the Surface of Workpieces in Cylindrical Grinding, Hao Yanping, Engineering Technology II; Engineering Technology I; Metallurgy and Metalworking; DOI: 10.16525 / j.cnki.cn14-1134 / th.2004.03.016" mentions that rounding the sharp corners of the grinding wheel with an oilstone can control the appearance of spiral marks during roll grinding. However, in actual production, it has been found that while rounding the edges does prevent the appearance of spiral marks in the early stages of grinding, the angle of newly appearing sharp corners decreases rapidly with the small amount of wear on the grinding wheel (see...). Figure 1 and Figure 2 This increases the pressure on the edge of the grinding wheel. The new, smaller angled edges will continue to cause spiral patterns to appear. Summary of the Invention

[0009] The purpose of this invention is to provide a grinding process and detection method for removing spiral marks on rolling mill rolls, which can effectively remove spiral marks on the surface of grinding rolling mill rolls, effectively control the surface quality of the grinding rolling mill rolls, and ultimately improve the surface quality of rolled sheet.

[0010] To achieve the above objectives, the present invention employs the following technical solution:

[0011] A grinding process for removing spiral marks on rollers includes rough grinding, semi-finish grinding, and finish grinding. After the rough grinding process, the grinding wheel shape is dressed by dressing the two sides of the grinding wheel into a transition arc shape according to the dressing curve. The dressing curve is established according to the following rules: select the center of a circle on a straight line 10mm away from the side of the grinding wheel, and the distance from the center of the circle to the end of the grinding wheel is the radius. Select a circle with a radius of 100mm to 500mm as the arc curve as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve.

[0012] Grinding process parameters are shown in Table 2:

[0013] Table 2. Roll grinding program parameters of the present invention

[0014]

[0015] The grinding wheel is selected with a grit size of F46 to F100, a hardness of J to N, a microstructure of 5 to 8, an abrasive ratio of 52% to 46%, and a resin bond.

[0016] The cutting fluid concentration is 3% to 5%.

[0017] The diamond pen should be tilted downwards at an angle of 5° to 10°.

[0018] The rolls are aligned and adjusted to ensure that the roll alignment error is within 0.03mm; the real-time roll profile deviation is within 0.002mm.

[0019] A method for inspecting the spiral pattern of a rolling mill roll involves setting the rolling mill speed to 50-70 revolutions per minute after grinding and using a strong flashlight to inspect the spiral pattern on the rolling mill roll surface.

[0020] Since the rolls are ground using the same grinding wheel on a single grinding machine, if the grinding wheel is dressed before rough grinding, the transition arc of the dressed grinding wheel will be completely consumed during the rough grinding process, resulting in no transition arc on the grinding wheel during semi-finish grinding and finish grinding. Semi-finish grinding removes the marks from rough grinding, and rough grinding does not require dressing. Dressing the grinding wheel would result in waste of the grinding wheel. Therefore, this invention involves dressing the grinding wheel shape after the rolls have been rough ground.

[0021] The grinding wheel is automatically dressed to a transition arc shape along the dressing curve on both sides. The dressing process is observed while dressing the grinding wheel, and the dressing quality is checked upon completion. After confirming there are no abnormalities, two semi-finish grinding processes are performed. Semi-finish grinding 1 mainly removes the marks from the coarse grinding, and semi-finish grinding 2 eliminates the spiral marks, ensuring that the surface roughness of the roll meets the requirements, thus preparing for fine grinding. Finally, fine grinding is performed.

[0022] During semi-finishing and finish grinding, set appropriate grinding parameters according to the required surface roughness of the roll. Reducing the grinding wheel linear speed can decrease the hardness of the grinding wheel, increasing the roll speed can increase the roll hardness, reducing the transverse and longitudinal feed can decrease the depth of cut, and reducing the grinding current can decrease the pressure between the grinding wheel and the roll (see Table 2). Observe the lubrication status of the bearing pads during grinding to prevent poor lubrication from causing thermal expansion and deformation of the bearing pads, wear, and resulting in misalignment of the roll.

[0023] After the roll grinding is completed, the cutting fluid is scraped off and the roll surface quality is inspected. Because the high-speed rotation of the roll makes the spiral marks on the surface more visible, the roll speed is set to 50-70 rpm after grinding, and a strong flashlight is used to inspect the spiral marks on the roll surface. This ensures that no spiral marks are detected during subsequent oilstone polishing.

[0024] This invention modifies the shape of the grinding wheel: the edge of the grinding wheel is right-angled, directly contacting the roller. During longitudinal feed, the pressure at the edge of the grinding wheel is greater than the pressure at the center, thus making it prone to spiral marks (see...). Figure 7 The edge of the grinding wheel is now ground into a transition arc shape to reduce or eliminate pressure on the edge, preventing the formation of spiral patterns (see...). Figure 8 ).

[0025] This invention allows for direct editing of grinding curve programs, ensuring high efficiency and safety. It also guarantees control over the spiral pattern during roll grinding.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1) This invention achieves the goal of completely eliminating spiral marks from rolling mills and improving the surface quality of the sheet material; it solves the problem of repeated grinding after spiral marks frequently appear on the rolling mills, thus saving energy and increasing efficiency.

[0028] 2) The method for inspecting the spiral marks of rolls provided by this invention improves the detection capability of spiral marks of rolls, eliminates the factors that cause spiral marks to appear when the rolls are ground with a grinding wheel, and solves the problem that no spiral marks are visible after the rolls are ground, but spiral marks appear when the rolls are polished with an oilstone after they are removed from the mill.

[0029] 3) This invention utilizes a grinding curve program to automatically dress the grinding wheel, effectively avoiding the safety hazards to operators caused by manually dressing high-speed rotating grinding wheels; at the same time, it solves the problem of unstable applied force and angle when manually dressing grinding wheels, ensuring the dressing effect; thus, the grinding wheel dressing work is not limited by equipment space, reducing manual labor, saving grinding wheel dressing time, reducing the frequency of grinding wheel dressing, and effectively improving equipment utilization.

[0030] 4) A comparison of the effects of existing technologies and the present invention is shown in Table 6:

[0031] Table 6

[0032] Existing grinding methods 95% of the rolls are free of spiral marks. 50% of the rolls are free of spiral marks Spiral marks frequently appear Method of the present invention 100% rolls are free of spiral marks 100% rolls are free of spiral marks No spiral mark . Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating how existing technology can round off the sharp corners of a grinding wheel.

[0034] Figure 2 This is a schematic diagram showing how the fillet radius of the grinding wheel in existing technology decreases rapidly as the grinding wheel is worn down.

[0035] Figure 3 This is a design drawing of the grinding wheel dressing curve of the present invention.

[0036] Figure 4 This is a schematic diagram of the grinding wheel dressing curve of the present invention.

[0037] Figure 5 This is a schematic diagram of the grinding wheel edge being ground into a transition arc shape according to the present invention.

[0038] Figure 6 This is a schematic diagram showing that the transition arc of the grinding wheel edge gradually decreases as the grinding wheel is consumed.

[0039] Figure 7 This diagram illustrates how the un-ground transition arc at the edge of the grinding wheel can easily produce spiral marks during grinding.

[0040] Figure 8 This is a schematic diagram showing how grinding the edge of the grinding wheel to a transition arc shape makes it less likely for spiral patterns to appear during the grinding process.

[0041] In the diagram: 1-rounded corner, 2-edge after rounded corner is ground off, 3-grinding wheel, 4-transition arc, 5-edge after transition arc is ground off, 6-roll. Detailed Implementation

[0042] The present invention will be described in more detail through embodiments. These embodiments are merely descriptions of the best mode of the invention and do not limit the scope of the invention in any way.

[0043] See Figures 3-6 A grinding process for removing spiral marks on rollers includes rough grinding, semi-finish grinding, and finish grinding. After the rough grinding process, the grinding wheel shape is dressed by dressing the two sides of the grinding wheel into a transition arc shape according to the dressing curve. The dressing curve is established according to the following rules: select a circle with a center on a straight line 10mm away from the side of the grinding wheel, and the distance from the center to the end of the grinding wheel is the radius. Select a circle with a radius of 100mm to 500mm as the arc curve, which serves as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve (see figure). Figure 3 , Figure 4 ).

[0044] The radius of the circle determines the height of the transition arc, avoiding an excessively high transition arc angle, which would result in poor performance and waste of the grinding wheel. During the grinding wheel dressing process, observe its condition; grinding can be stopped once a straight line is reached, thus preventing waste of the grinding wheel.

[0045] The grinding wheel edge of this invention has a transition arc shape. As the grinding wheel wears down, the angle of the newly emerging edge decreases slowly and becomes larger. The new, larger angle of the edge can slow down the appearance of spiral marks (see...). Figure 5 , Figure 6 Furthermore, by combining the setting and control of process parameters in this invention, the problem of spiral marks appearing during roll grinding can be effectively solved.

[0046] Grinding process parameters are shown in Table 2:

[0047] Table 2. Roll grinding program parameters of the present invention

[0048]

[0049] The current in Table 2 is the current of the roll grinding machine, and the model of the roll grinding machine is Herkules.

[0050] The grinding wheel is selected with a grit size of F46 to F100, a hardness of J to N, a microstructure of 5 to 8, an abrasive ratio of 52% to 46%, and a resin bond.

[0051] The cutting fluid concentration is 3% to 5%.

[0052] The diamond pen should be tilted downwards at an angle of 5° to 10°.

[0053] The rolls are aligned and adjusted to ensure that the roll alignment error is within 0.03mm; the real-time roll profile deviation is within 0.002mm.

[0054] A method for inspecting the spiral pattern of a rolling mill roll involves setting the rolling mill speed to 50-70 revolutions per minute after grinding and using a strong flashlight to inspect the spiral pattern on the rolling mill roll surface.

[0055] Example 1:

[0056] A grinding process for removing spiral marks on rollers includes rough grinding, semi-finish grinding, and finish grinding. After the rough grinding process, the grinding wheel shape is dressed by dressing the two sides of the grinding wheel into a transition arc shape according to the dressing curve. The dressing curve is established according to the following rules: select the center of a circle on a straight line 10mm away from the side of the grinding wheel, and the distance from the center of the circle to the end of the grinding wheel is the radius. Select a circle with a radius of 200mm as the arc curve as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve.

[0057] Grinding process parameters are shown in Table 3:

[0058] Table 3. Roll Grinding Program Parameters for Example 1

[0059]

[0060]

[0061] The grinding wheel selected has an F60 grit size, a K hardness, a No. 6 microstructure, an abrasive ratio of 52% to 46%, and a resin bond.

[0062] Check the grinding wheel spindle for axial movement, the worktable for crawling and wobbling, and the diamond drill for looseness. Ensure the diamond drill angle is tilted downwards at 5°–10°. Address any problems promptly. Check the cutting fluid concentration to ensure it is 3%–5%. Add cutting fluid if necessary.

[0063] Before grinding the rolls, the measurement system is calibrated, and the roll neck and bearings are inspected for defects. Defective rolls and bearings are repaired before grinding. The rolls are then aligned and adjusted to ensure that the alignment error is within 0.03 mm.

[0064] Select a grinding program to perform rough grinding on the rolls (grinding parameters are shown in Table 3). During the grinding process, observe the measurement system for any abnormalities and for any fluctuations in the grinding current. Semi-finish grinding can only proceed after the real-time curve deviation of the roll profile reaches within 0.002 mm and the grinding current shows no fluctuations.

[0065] A method for inspecting spiral patterns on rolling mill rolls involves setting the roll speed to 55 rpm after grinding and using a strong flashlight to inspect the spiral patterns on the roll surface. No spiral patterns are found on the roll surface. After the roll is removed from the mill, it is polished with an oilstone, and no spiral pattern marks are found.

[0066] Example 2:

[0067] A grinding process for removing spiral marks on rollers includes rough grinding, semi-finish grinding, and finish grinding. After the rough grinding process, the grinding wheel shape is dressed by dressing the two sides of the grinding wheel into a transition arc shape according to the dressing curve. The dressing curve is established according to the following rules: select the center of a circle on a straight line 10mm away from the side of the grinding wheel, and the distance from the center of the circle to the end of the grinding wheel is the radius. Select a circle with a radius of 300mm as the arc curve as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve.

[0068] Grinding process parameters are shown in Table 4:

[0069] Table 4. Roll Grinding Program Parameters for Example 2

[0070]

[0071] The grinding wheel selected should have an F80 grit size, J hardness, No. 6 microstructure, 52%–46% abrasive content, and be resin-bonded. Check the grinding machine spindle for axial movement, the worktable for crawling and wobbling, and the diamond pen for looseness, ensuring the diamond pen is tilted downwards at a 5°–10° angle. Address any problems promptly. Check the cutting fluid concentration to ensure it reaches 3%–5%; add cutting fluid if necessary.

[0072] Before grinding the rolls, the measurement system is calibrated, and the roll neck and bearings are inspected for defects. Defective rolls and bearings are repaired before grinding. The rolls are then aligned and adjusted to ensure that the alignment error is within 0.03 mm.

[0073] Select a grinding program to perform rough grinding on the rolls (grinding parameters are shown in Table 4). During the grinding process, observe the measurement system for any abnormalities and for any fluctuations in the grinding current. Semi-finish grinding can only proceed after the real-time deviation of the roll profile curve reaches within 0.002 mm and the grinding current shows no fluctuations.

[0074] A method for inspecting spiral patterns on rolling mill rolls involves setting the roll speed to 60 rpm after grinding and using a strong flashlight to inspect the spiral patterns on the roll surface. No spiral patterns are found on the roll surface. After the roll is removed from the mill, it is polished with an oilstone, and no spiral pattern marks are found.

[0075] Example 3:

[0076] A grinding process for removing spiral marks on rollers includes rough grinding, semi-finish grinding, and finish grinding. After the rough grinding process, the grinding wheel shape is dressed by dressing the two sides of the grinding wheel into a transition arc shape according to the dressing curve. The dressing curve is established according to the following rules: select the center of a circle on a straight line 10mm away from the side of the grinding wheel, and the distance from the center of the circle to the end of the grinding wheel is the radius. Select a circle with a radius of 400mm as the arc curve as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve.

[0077] Grinding process parameters are shown in Table 5:

[0078] Table 5. Roll Grinding Program Parameters for Example 3

[0079]

[0080] The grinding wheel selected should have an F46 grit size, K hardness, No. 5 microstructure, 52%–46% abrasive content, and be resin-bonded. Check the grinding machine spindle for axial movement, the worktable for crawling and wobbling, and the diamond pen for looseness, ensuring the diamond pen is tilted downwards at a 5°–10° angle. Address any problems promptly. Check the cutting fluid concentration to ensure it reaches 3%–5%; add cutting fluid if necessary.

[0081] Before grinding the rolls, the measurement system is calibrated, and the roll neck and bearings are inspected for defects. Defective rolls and bearings are repaired before grinding. The rolls are then aligned and adjusted to ensure that the alignment error is within 0.03 mm.

[0082] Select a grinding program to perform rough grinding on the rolls (grinding parameters are shown in Table 5). During the grinding process, observe the measurement system for any abnormalities and for any fluctuations in the grinding current. Semi-finish grinding can only proceed after the real-time deviation of the roll profile curve reaches within 0.002 mm and the grinding current shows no fluctuations.

[0083] A method for inspecting spiral patterns on rolling mill rolls involves setting the roll speed to 70 rpm after grinding and using a strong flashlight to inspect the spiral patterns on the roll surface. No spiral patterns are found on the roll surface. After the roll is removed from the mill, it is polished with an oilstone, and no spiral pattern marks are found.

Claims

1. A grinding process for removing spiral marks from rolling mill rolls, comprising rough grinding, semi-finish grinding, and finish grinding, characterized in that, After the rough grinding process, the grinding wheel shape is dressed. The two sides of the grinding wheel are dressed into transition arcs according to the dressing curve. The dressing curve is established according to the following rules: Select the center of a circle on a straight line 10mm away from the side of the grinding wheel. The distance from the center of the circle to the end of the grinding wheel is the radius. Select a circle with a radius of 100mm to 500mm as the arc curve as the transition arc on the left and right sides. Connect the tangents of the two circles with the transition arc to obtain the dressing curve. The grinding process parameters are as follows: Rough grinding: grinding wheel linear speed 25-32 m / s, roller speed 35-40 rpm, large carriage speed 2000-2200 mm / min, grinding wheel feed 0.01-0.015 mm / min, current 20-25 M%. First semi-finish grinding: grinding wheel linear speed 18-23 m / s, roller speed 38-45 rpm, large carriage speed 1500-1800 mm / min, grinding wheel feed 0.006-0.008 mm / min, current 13-18 M%. Second semi-finish grinding: grinding wheel linear speed 16-20 m / s, roller speed 45-48 rpm, large carriage speed 800-1100 mm / min, grinding wheel feed 0.003-0.005 mm / min, current 5-12 M%. Fine grinding: grinding wheel linear speed 13-18 m / s, roller speed 48-52 rpm, large slide 400-600 mm / min, minimum grinding wheel feed 0.003 mm / min, current 3-5 MΩ.

2. The grinding process for removing spiral marks from rolls according to claim 1, characterized in that, The grinding wheel is selected with a grit size of F46 to F100, a hardness of J to N, a microstructure of 5 to 8, an abrasive ratio of 52% to 46%, and a resin binder.

3. The grinding process for removing spiral marks from rolls according to claim 1, characterized in that, The cutting fluid concentration is 3% to 5%.

4. The grinding process for removing spiral marks from rolls according to claim 1, characterized in that, The diamond pen should be tilted downwards at an angle of 5° to 10°.

5. The grinding process for removing spiral marks from rolls according to claim 1, characterized in that, The rolls are aligned and adjusted to ensure that the roll alignment error is within 0.03mm; the real-time roll profile deviation is within 0.002mm.

6. A method for inspecting spiral marks on rolling mill rolls, characterized in that, This method is used to inspect roll workpieces ground using the grinding process for removing roll spiral marks as described in any one of claims 1-5. After grinding, the roll speed is set to 50-70 rpm, and the spiral marks on the roll surface are detected by irradiation with a flashlight.

Images