A wind power bearing raceway curvature radius machining error prediction method

Abstract

The present application relates to the technical field of machine tool error, and discloses a wind power bearing raceway curvature radius machining error prediction method, comprising the following steps: S1. According to the geometric structure of the heavy vertical lathe, a geometric error transmission model of the heavy vertical lathe is established by using rigid body kinematics, and the error transmission law of the machine tool components is described; S2. The geometric error of the machine tool is measured by using a laser interferometer, and the measurement is carried out by extracting feature points; S3. According to the error model and the transformation matrix, the geometric error is superimposed to obtain the position error of any point, and the position error and the profile error between points are calculated; S4. The actual machined wind power bearing raceway curvature radius is measured by using a three-coordinate measuring instrument, and compared with the predicted value, so as to verify the accuracy of the error prediction method, and the present application can provide theoretical and practical guidance for the design and manufacture of heavy machine tools and the vertical turning process of large rotary parts.

Description

Technical Field

[0001] This invention belongs to the field of machine tool error technology, specifically relating to a method for predicting the machining error of the raceway curvature radius of wind turbine bearings. Background Technology

[0002] As one of the most promising clean energy sources, wind power has received high attention from countries around the world. In wind power systems, wind turbine bearings are large core components, and achieving the required machining precision for these bearings places special demands on metal processing machine tools. For high-precision, large components like wind turbine bearings, only heavy-duty CNC machine tools can be used for machining. As mechanical equipment for machining large and heavy workpieces, heavy-duty CNC machine tools are characterized by large structural dimensions, high component weight, and long working stroke. Due to the large stroke and heavy load of the components and the large size of the workpieces, the geometric errors have a greater impact on the machining errors of the workpieces.

[0003] Therefore, researching how to predict workpiece machining errors based on measured machine tool geometric errors, and then effectively reducing workpiece machining errors by adjusting relevant errors, is of great significance for actual production. In view of this, we propose a method for predicting the machining error of the raceway curvature radius of wind turbine bearings. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention proposes a method for predicting the machining error of the raceway curvature radius of wind turbine bearings.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for predicting the machining error of the raceway curvature radius of a wind turbine bearing includes the following steps:

[0007] S1. Based on the geometric structure of the heavy-duty vertical lathe, establish a geometric error transmission model of the heavy-duty vertical lathe using rigid body kinematics, and use rigid body kinematics to describe the error transmission law of the machine tool components.

[0008] S2. The geometric error of the machine tool is measured using an XD LASER 6D laser interferometer by extracting feature points.

[0009] S3. Based on the error model and transformation matrix, the geometric errors are superimposed to obtain the position error of any point, and the position error and contour error between points are calculated.

[0010] S4. Use a coordinate measuring machine to measure the radius of curvature of the raceway of the actual wind turbine bearing and compare it with the predicted value to verify the accuracy of the error prediction method.

[0011] Preferably, the geometry of the heavy-duty vertical lathe includes a bed and a worktable. The bed includes a column, a crossbeam, a horizontal slide, and a vertical slide. The lathe has four motion axes: the W-axis of the crossbeam, the X-axis of the horizontal slide, the Z-axis of the vertical slide, and the C-axis of the spindle worktable.

[0012] Preferably, each moving part of the heavy-duty vertical lathe has six degrees of freedom in its direction of movement, and each degree of freedom will generate a corresponding geometric error under the constraint conditions.

[0013] Geometric errors include three linear errors and three rotation angle errors. The three linear errors include one positioning error and two straightness errors; the three rotation angle errors include roll angle error, pitch angle error and yaw angle error. These geometric errors are called position-related geometric errors.

[0014] Preferably, the geometric error propagation model is established based on the deviations between the components of a heavy-duty vertical lathe.

[0015] Preferably, in step S2, for a wind turbine bearing with a raceway curvature radius R = 26.9 mm and a ball diameter D = 50.8 mm, the geometric error of any position of the moving part of the heavy-duty vertical lathe is obtained based on the established error model and error fitting formula.

[0016] The feature points were extracted by taking 9 feature points at 5° intervals along the upper and lower raceway curves of the bearing raceway section. The horizontal slide X-axis travel range is [1196, 1208], and the vertical slide Z-axis travel range is [326, 374]. The unit of the travel range is millimeters.

[0017] Preferably, in step S3, the curve profile error refers to the amount of variation between the actual profile and the ideal profile of the curve, which is obtained from the position error.

[0018] Preferably, in step S4, the curvature radius of the raceway on the wind turbine bearing is selected for verification. Using a coordinate measuring machine, the measuring probe selects the raceway cross-sectional curves in four directions at 90-degree intervals along the circumference of the machined wind turbine bearing, and measures their curvature radii respectively to obtain the actual cross-sectional curve curvature radius of the raceway on the wind turbine bearing.

[0019] Compared with the prior art, the technical effects and advantages of the present invention are:

[0020] 1. The established error transmission model of heavy-duty vertical lathe can reveal the influence law of geometric error of heavy-duty vertical lathe on the machining error of wind turbine bearing raceway, and thus provide a theoretical basis for machine tool manufacturers to reduce machine tool assembly error and effectively reduce workpiece machining error by adjusting relevant errors on the production site.

[0021] 2. When machining large rotating parts such as wind turbine bearings on heavy-duty vertical lathes, the curvature radius of the raceway of the wind turbine bearing can be predicted even when only the geometric error of the machine tool is known. The error between the predicted value and the measured value is very small, providing a new machine tool performance evaluation method for machine tool manufacturers.

[0022] 3. Provided that the machine tool's geometric error meets the usage standards, it is not necessary to use a coordinate measuring machine to measure the raceway curvature radius of the wind turbine bearings being processed, thus reducing production steps and lowering the enterprise's manufacturing costs. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the heavy-duty vertical lathe of the present invention;

[0024] Figure 2 This is a topological diagram of the heavy-duty vertical lathe of the present invention;

[0025] Figure 3 This is a structural schematic diagram of the six geometric errors of the horizontal slide block of the present invention;

[0026] Figure 4 This is a structural schematic diagram of the six geometric errors of the workbench of the present invention;

[0027] Figure 5 This is a curve showing the positioning error of the horizontal slide block in this invention.

[0028] Figure 6 This is a fitting curve of the Y-axis straightness error of the horizontal slide block according to the present invention;

[0029] Figure 7 This is a fitting curve of the Z-axis straightness error of the horizontal slide block according to the present invention;

[0030] Figure 8 This is a curve showing the fitting of the rolling angle error of the horizontal slide block according to the present invention;

[0031] Figure 9 This is a curve showing the fitting of the pitch angle error of the horizontal slide block according to the present invention.

[0032] Figure 10 This is a curve showing the fitting of the horizontal slide block yaw angle error of the present invention;

[0033] Figure 11 This is a curve showing the fitting of the vertical slide block positioning error of the present invention;

[0034] Figure 12 This is a fitting curve of the straightness error of the vertical slide block in the X direction according to the present invention;

[0035] Figure 13 This is a fitting curve of the straightness error in the Y direction of the vertical slide block according to the present invention;

[0036] Figure 14 This is a curve showing the fitting of the vertical slide ram rolling angle error according to the present invention;

[0037] Figure 15 This is a curve showing the fitting of the vertical slide ram pitch angle error of the present invention;

[0038] Figure 16 This is a curve showing the fitting of the vertical slide block yaw angle error of the present invention;

[0039] Figure 17 This is a cross-sectional schematic diagram of the fit between the raceway and the balls in the wind turbine bearing of the present invention;

[0040] Figure 18 This is a schematic diagram of the position error of the present invention;

[0041] Figure 19 This is a curve showing the ideal and predicted fitting of the upper raceway in this invention;

[0042] Figure 20 This is a curve showing the ideal and predicted fitting of the lower raceway in this invention;

[0043] Figure 21 This is a schematic diagram of the contour error of the present invention.

[0044] In the diagram: 1. Bed; 2. Post; 3. Beam; 4. Horizontal slide; 5. Vertical slide; 6. Worktable. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The following is in conjunction with the appendix Figure 1-21 This application will be described in further detail.

[0047] This application discloses a method for predicting the machining error of the raceway curvature radius of wind turbine bearings, including the following steps:

[0048] S1. Based on the geometry of the heavy-duty vertical lathe, establish a geometric error transmission model of the heavy-duty vertical lathe using rigid body kinematics, and use rigid body kinematics to describe the error transmission law of the machine tool components.

[0049] S2. The geometric error of the machine tool is measured using an XD LASER 6D laser interferometer by extracting feature points;

[0050] S3. Based on the error model and transformation matrix, the geometric errors are superimposed to obtain the position error of any point, and the position error and contour error between points are calculated.

[0051] S4. Use a coordinate measuring machine to measure the radius of curvature of the raceway of the actual machined wind turbine bearing and compare it with the predicted value to verify the accuracy of the error prediction method.

[0052] The DVT500 heavy-duty vertical lathe manufactured by Qizhong CNC Equipment Co., Ltd. has a maximum turning diameter of 5000mm, a maximum machining height of 4000mm, and a maximum workpiece weight of 50t. The structure of the heavy-duty vertical lathe is as follows: Figure 1 As shown, the lathe has four motion axes: the W-axis of the crossbeam, the X-axis of the horizontal ram, the Z-axis of the vertical ram, and the C-axis of the spindle table. Based on the machine tool structure and the motion relationships between its components, it is known that the lathe has two motion chains: one from the bed to the workpiece and the other from the bed to the cutting tool. The machine tool topology is shown below. Figure 2 As shown.

[0053] When a machine tool is working, each moving part of the machine tool has six degrees of freedom in its direction of movement. Each degree of freedom will generate a corresponding geometric error under the constraint conditions, namely three linear errors: one positioning error and two straightness errors, and three rotation angle errors: roll angle error, pitch angle error and yaw angle error. All of these can be called position-related geometric errors.

[0054] like Figure 3 , 4 The figures show six geometric errors of the horizontal slide and the spindle of the worktable of a heavy-duty vertical lathe. Among them, δ... xx For the positioning error of the horizontal slide block, δ xy For the straightness error of the horizontal slide block in the Y direction, δ xz For the straightness error of the horizontal slide block in the Z direction, ε xx For the roll angle error, ε xy For pitch angle error, ε xz This represents the yaw angle error; δ cx For the positioning error of the rotary table, δ cy For the straightness error of the rotary table in the Y direction, δ cz For the straightness error of the rotary table in the Z direction, ε cx For the roll angle error of the rotary table, ε cy For the pitch angle error of the rotary table, ε cz This represents the yaw angle error of the rotary table.

[0055] In rigid body kinematics, translational and rotational transformations are primarily used to describe the position of an object in a specified coordinate system. This embodiment establishes a geometric error model based on the deviations between various components of a heavy-duty vertical lathe, using I...4×4 Let T be a 4×4 identity matrix. Then, for the relative motion of the machine tool components, the ideal transformation matrix T between the machine tool components can be obtained by analysis. s and the actual error transformation matrix T p :

[0056] (1) If there is no relative motion between bed 1 and column 2 without considering assembly errors, then their ideal motion characteristic transformation matrix T under error-free conditions is... s12 The actual motion characteristic transformation matrix T considering errors p12 for:

[0057] T s12 =I 4×4 (1)

[0058] T p12 =I 4×4 (2)

[0059] (2) In actual work, the position of the W-axis of the crossbeam 3 is determined based on the workpiece height before machining and tool setting. During machining, there is still no relative motion between the column 2 and the crossbeam 3. Therefore, its ideal motion characteristic transformation matrix T s23 Transformation matrix T of actual motion characteristics p23 for:

[0060] T s23 =I 4×4 (3)

[0061] T p23 =I 4×4 (4)

[0062] (3) The horizontal slide 4 performs a linear translational motion on the crossbeam 3. Then its ideal motion characteristic transformation matrix T s34 Transformation matrix T of actual motion characteristics p34 for:

[0063]

[0064]

[0065] In the formula, x 34 The z represents the horizontal feed distance of the moving axis. 45 S represents the vertical feed distance. 45 ε represents the perpendicularity error of the horizontal slide X-axis relative to the reference vertical slide Z-axis. x34 ε represents the roll angle error between component 3 and component 4. y34 ε represents the pitch error between component 3 and component 4. z34 δ represents the yaw angle error between component 3 and component 4. x34δ represents the positioning error of the horizontal slide block 4. y34 δ represents the Y-direction straightness error of the horizontal slide block 4. z34 This indicates the Z-direction straightness error of the horizontal slide block 4.

[0066] (4) When the vertical slide 5 is fixed to the horizontal slide 4 and performs linear vertical motion, its ideal motion characteristic transformation matrix T s45 Transformation matrix T of actual motion characteristics p45 for:

[0067]

[0068]

[0069] In the formula, ε x45 ε represents the rolling angle error between component 4 and component 5. y45 ε represents the pitch error between component 4 and component 5. z45 δ represents the yaw angle error between component 4 and component 5. x45 δ represents the positioning error of the vertical slide block 5. y45 δ represents the Y-direction straightness error of the vertical slide block 5. z45 This indicates the Z-direction straightness error of the vertical slide block 5.

[0070] (5) The worktable 6 is connected to the bed 1 and rotates. θ represents its rotation angle. Then its ideal motion characteristic transformation matrix R s16 Transformation matrix T of actual motion characteristics p16 for:

[0071]

[0072]

[0073] In the formula, ε x16 ε represents the roll angle error of the rotary table. y16 ε represents the pitch angle error of the rotary table. z16 The yaw angle error of the rotary table is represented by δ. x16 δ represents the positioning error of the rotary table. y16 δ represents the straightness error of the rotary table in the Y direction. z16 This indicates the straightness error in the Z-direction of the rotary table.

[0074] When the machine tool is actually working, there is no relative motion between the tool and the vertical slide, and between the workpiece and the rotary table after clamping. Therefore, the homogeneous transformation matrix of the tool coordinate system of the tool forming point generated by the tool movement trajectory can be expressed by the vertical slide, and the homogeneous transformation matrix of the workpiece coordinate system of the workpiece forming point can be expressed by the rotary table.

[0075] Let the coordinates of the tool forming point in the tool coordinate system be as follows under ideal conditions:

[0076] P t =[P tx P ty P tz 1] T (11)

[0077] In the formula, P tx P represents the x-coordinate of the tool forming point under ideal conditions. ty P represents the y-coordinate of the tool forming point under ideal conditions. tz This represents the z-coordinate of the tool forming point under ideal conditions.

[0078] The coordinates of the actual forming point of the workpiece in the workpiece coordinate system are:

[0079] P w =[P wx P wy P wz 1] T (12)

[0080] In the formula, P wx P represents the x-coordinate of the actual forming point of the workpiece. wy P represents the y-coordinate of the actual forming point of the workpiece. wz This represents the z-coordinate of the actual forming point of the workpiece.

[0081] Under error-free conditions, the tool forming point and the workpiece forming point should coincide. Therefore, from the topological kinematic chain of a heavy-duty vertical lathe:

[0082] P t =R s16 -1 T s12 T s23 T s34 T s45 P (13)

[0083] Where: P is the origin of the tool cutting point in the workpiece coordinate system, i.e.

[0084] P = [0 0 0 1] T (14)

[0085] In actual motion, i.e., considering errors, each motion axis introduces geometric errors during movement. The actual coordinate position of the tool cutting point in the workpiece coordinate system is:

[0086] P w =(R s16 T p16 )-1 T s12 T p12 T s23 T p23 T s34 T p34 T s45 T p45 P (15)

[0087] Considering the geometric errors of heavy-duty vertical lathes, the machine tool geometric error propagation model can be obtained from the topological kinematic chain of heavy-duty vertical lathes:

[0088] P e =[e x e y e z 1] T =P w -P t (16)

[0089] In the formula, e x e represents the machining error in the x-direction of a heavy-duty vertical lathe. y e represents the machining error in the y-direction of a heavy-duty vertical lathe. z This refers to the machining error in the z-direction of a heavy-duty vertical lathe.

[0090] The geometric error propagation model represents the deviation of the moving parts of the machine tool at each position. The perpendicularity error generated by the two linear axes during assembly can be measured by precision measuring equipment, or identified by the straightness error of the horizontal slide along the Z-axis and the straightness error of the vertical slide along the X-axis. Therefore, the magnitude of its influence should be determined according to the change of the perpendicularity error with the machine tool stroke.

[0091] In the process of measuring and analyzing the geometric errors of heavy machine tools, the API XD LASER 6D laser interferometer was used to measure the machine tool errors. The test site for measuring heavy vertical lathes consisted of several components, including a wireless data transceiver, a 6D sensor, a weather station, a laser interferometer, and a roll angle reference level. The wireless data transceiver was used to collect measurement data and transmit it to a computer for processing. The 6D sensor was the sensor in the system used to measure the geometric errors of the machine tool. The weather station was used to record data such as ambient temperature and humidity to account for the influence of environmental factors on the measurement results. The laser interferometer was used to measure the geometric errors of the machine tool, achieving high-precision measurement through the principle of laser interferometry. The roll angle reference level was used to calibrate the levelness or provide reference angle information.

[0092] The principle of machine tool geometric error measurement involves laser interferometry. Laser interferometry utilizes the principle of laser interference to measure the shape, size, and position of an object's surface. By installing a laser interferometer on a machine tool, the relative position and geometric errors between various machine tool components can be measured in real time, thereby evaluating the machine tool's accuracy and stability. The laser interferometer uses the interference effect of a laser beam to accurately measure the surface shape of an object, and analyzes the changes in interference fringes to calculate the geometric error of the machine tool, thus improving the machining accuracy and efficiency of the machine tool.

[0093] By fitting the geometric error measurement results with a polynomial function, a trend diagram of geometric error variation under the machine tool's moving axis travel can be obtained. The error trends of the six geometric errors of the horizontal slide X-axis under the random machine tool travel are shown below. Figure 5-10 As shown, the error trends of the six geometric errors of the vertical slide Z-axis along the random bed travel are as follows: Figure 11-16 As shown, the verticality error between the horizontal slide and the vertical slide is 10.5 arcseconds.

[0094] The scatter plot shows that the overall trend of the horizontal slide positioning error increases with the increase of the machine tool stroke, and the error reaches its maximum value at 1700mm, then decreases slightly and tends to stabilize. The Y-axis straightness error and Z-axis straightness error have similar trends, decreasing first and then increasing with the increase of the machine tool stroke, with the error value being the smallest at the middle position. The roll angle error, pitch angle error and yaw angle error all increase with the increase of the machine tool stroke.

[0095] The vertical slide positioning error generally increases with the increase of machine tool stroke, reaching its maximum value at 400mm; the X-axis straightness error first decreases and then increases with the increase of machine tool stroke, reaching its maximum value at 350mm, and then decreases and then increases again; the Y-axis straightness error and roll angle error fluctuate significantly with no obvious pattern under the machine tool stroke; the pitch angle error and yaw angle error have similar trends, both increasing with the increase of machine tool stroke, reaching their maximum value at the farthest end of the stroke.

[0096] In the process of predicting and verifying the machining error of the wind turbine bearing raceway, the cross-sectional schematic diagram of the fit between the wind turbine bearing raceway and the balls is shown below. Figure 17 As shown, the radius of curvature of the bearing raceway curve is R = 26.9 mm, and the ball diameter is D = 50.8 mm. The positional and shape errors of the bearing raceway cross-section characteristic curve are evaluated. Based on the established error model and error fitting formula, the geometric error of any position of the moving part of the heavy-duty vertical lathe can be obtained. The bearing raceway positional error can be predicted based on the positional error of the moving part of the heavy-duty vertical lathe. Furthermore, since the bearing raceway cross-section is a characteristic curve, its profile error can be calculated from the positional error.

[0097] The specific details of bearing raceway position error prediction are as follows:

[0098] Nine feature points are extracted from the upper and lower raceway curves at 5° intervals along the bearing raceway section. The horizontal slide block X-axis travel range is [1196, 1208], and the vertical slide block Z-axis travel range is [326, 374].

[0099] Based on the established error model, the position error at any point can be obtained by superimposing the geometric errors using the error transformation matrix. The position error refers to the deviation between the actual cutting point of the tool and its ideal position. Figure 18 As shown, let point P be a point on the ideal cutting trajectory, and point Q represent the actual position of point P after considering errors. The positional errors Δx and Δz between point Q and point P can be obtained from the error transformation matrix. The positional errors between points are calculated using the positional deviations between the ideal feature point and the feature point after considering errors. Then, by fitting each point, the bearing raceway prediction curve considering geometric errors can be obtained.

[0100] The positional errors of unmeasured points on the horizontal and vertical slides of a heavy-duty vertical lathe can be calculated using the geometric error fitting equation. Then, based on the error propagation model of the heavy-duty vertical lathe, the positional error at any point on the bearing raceway can be calculated using simulation software. The positional errors of each characteristic point on the upper and lower half of the bearing raceway are shown in Tables 1 and 2, respectively. The positive and negative signs indicate the direction of positional error variation in the coordinate system, and T represents the comprehensive positional error of each point. Furthermore, a comparison between the ideal and predicted curves of the upper and lower raceways of the wind turbine bearing can be obtained. Figure 19 , 20 As shown.

[0101] Table 1. Position error of feature points on the upper raceway (mm)

[0102] 1 1207.653 373.319 -0.092965 0.041582 0.101841 2 1205.571 372.235 -0.092872 0.041572 0.101752 3 1203.592 370.974 -0.092783 0.041556 0.101664 4 1201.730 369.546 -0.092699 0.041534 0.101578 5 1200.000 367.960 -0.092619 0.041507 0.101495 6 1198.415 366.230 -0.092546 0.041474 0.101414 7 1196.986 364.368 -0.092479 0.041434 0.101337 8 1195.725 362.389 -0.092419 0.041389 0.101263 9 1194.641 360.307 -0.092366 0.041337 0.101194

[0103] Table 2. Position error of feature points on the lower raceway (mm)

[0104]

[0105]

[0106] The specific details of bearing raceway profile error prediction are as follows:

[0107] Curve profile error refers to the variation between the actual profile and the ideal profile of a curve, and can be obtained from positional error, such as... Figure 21As shown, let point P be a point on the ideal cutting trajectory, and point Q represent the actual position of point P after considering the error. The curve profile error is the minimum absolute deviation between the actual position Q and the tangent at the ideal position P. It is the projection P' of the position error T onto the normal vector at point Q. Then, the distance between P and P' is the profile error. Since Δz and Δx are known, the point profile error is calculated using the positional deviation between the ideal feature point and the feature point after considering the error. The point profile error is then used to characterize the profile of the bearing raceway section curve. The calculation process is as follows:

[0108] Let the equation of the curve C be:

[0109] C=(x(t)z(t)1) T (17)

[0110] Then its tangent vector at point Q is:

[0111]

[0112] In the formula, u x u represents the x-component of the tangent vector at point Q. z This represents the z-component of the tangent vector at point Q.

[0113] set up:

[0114]

[0115] In the formula, N x Representing vectors The x-component, N z Representing vectors The z-axis component.

[0116] Then the curvature normal vector at point Q is:

[0117]

[0118] In the formula, n x Let n represent the x-component of the curvature normal vector at point Q. z This represents the z-component of the curvature normal vector at point Q.

[0119] Based on the positional error, the profile error can be obtained as follows:

[0120]

[0121] In the formula, e represents the position error, and x Q This represents the x-coordinate of point Q, x P Represents the x-coordinate and z-coordinate of point P. Q This represents the z-coordinate of point Q. P This represents the z-coordinate of point P.

[0122] The contour calculation process was programmed in MATLAB. The characteristic curve equations of the upper and lower raceways of the wind turbine bearing were obtained by fitting the feature points after considering the error. The feature point position error was substituted into the program to obtain the point contour error G of each ideal feature point of the wind turbine bearing raceway and the corresponding feature point after considering the error, as shown in Table 3.

[0123] Table 3 Feature point contour error (mm)

[0124]

[0125]

[0126] The calculated profile error at each point is essentially the variation of the radius of curvature of the ideal cross-section curve of the wind turbine bearing raceway relative to the radius of curvature of the predicted cross-section curve after considering the error. Based on this, the radius of curvature of the predicted cross-section curve of the wind turbine bearing raceway after considering the error is the average value of the radius of curvature of each point on the curve. Therefore, the radius of curvature of the predicted cross-section curve of the upper raceway of the wind turbine bearing is 26.9923 mm, and the radius of curvature of the predicted cross-section curve of the lower raceway is 26.9928 mm.

[0127] The specific details of the experimental verification are as follows:

[0128] To verify the accuracy of error prediction and error modeling, a coordinate measuring machine (CMM) can be used to measure the raceway of the bearing machined by the heavy-duty vertical lathe studied in this paper. The radius of curvature of the raceway on the wind turbine bearing is selected for verification. Using the CMM's measuring probe, the raceway cross-sectional curves are selected at 90-degree intervals along the circumference of the machined wind turbine bearing in four directions, and their radii of curvature are measured respectively. The actual cross-sectional radii of curvature of the raceway on the wind turbine bearing are shown in Table 4.

[0129] Table 4 Actual radius of curvature of the upper raceway (mm)

[0130] 26.9 26.9954 26.9951 26.9969 26.9962

[0131] Since the radius of curvature of the predicted cross-section curve of the raceway on the wind turbine bearing is 26.9923 mm, the relative error between the measured value and the predicted value is within 0.005 mm, and the relative error between the predicted value and the measured value is less than 5%, the established error transmission model and prediction model are relatively accurate.

[0132] In summary, the method for predicting the machining error of the raceway curvature radius of the wind turbine bearing first establishes a geometric error transmission model of the heavy-duty vertical lathe based on its geometry using rigid body kinematics, and then uses an XD LASER 6D laser interferometer to measure the geometric error of the machine tool. Nine feature points are extracted at 5° intervals along the upper and lower raceway curves of the bearing raceway section. The horizontal slide X-axis travel range is [1196, 1208], and the vertical slide Z-axis travel range is [326, 374].

[0133] Based on the established error model, the positional error of any point can be obtained by superimposing the geometric errors using the error transformation matrix. The positional error between points is calculated using the positional deviation between ideal feature points and feature points considering errors. The contour calculation process is programmed in MATLAB. By fitting the feature points of the upper and lower raceways of the wind turbine bearing with errors, the characteristic curve equations of the upper and lower raceways can be obtained. Substituting the feature point positional errors into the program yields the point contour error G of each ideal feature point and the corresponding feature point considering errors in the wind turbine bearing raceway. From this, the predicted cross-sectional curve curvature radius of the wind turbine bearing raceway considering errors can be obtained. Finally, a coordinate measuring machine is used to measure the curvature radius of the actual machined wind turbine bearing raceway and compare it with the predicted value.

[0134] This invention models and measures the geometric errors of heavy-duty vertical lathes. By combining a geometric error fitting function, it calculates the positional errors and contour errors of feature points on the bearing raceway cross-sectional curve, predicting the theoretical value of the radius of curvature of the raceway in wind turbine bearings machined by a heavy-duty vertical lathe. Experimental measurements verify this prediction, showing that the error between the predicted and measured values ​​is within a reasonable range. A mapping relationship between machine tool geometric errors and machining errors is established, and a method for calculating the predicted radius of curvature of the radius of curvature in machining large rotating workpieces using heavy-duty vertical lathe geometric errors is provided. This offers a new approach for machine tool manufacturers to reduce machine tool assembly errors and effectively reduce workpiece machining errors on the production floor by adjusting relevant errors.

[0135] This method for predicting the machining error of the raceway curvature radius of wind turbine bearings, by establishing an error model and measuring geometric errors, can accurately predict the theoretical value of the raceway curvature radius of wind turbine bearings machined on a heavy-duty vertical lathe. Experimental results show that the error between the predicted and measured values ​​is within a reasonable range, indicating that the method has high prediction accuracy.

[0136] This method establishes a mapping relationship between machine tool geometric errors and machining errors, providing machine tool manufacturers with a new approach to reduce machine tool assembly and machining errors. By adjusting relevant errors and reducing machine tool geometric errors, workpiece machining errors can be effectively reduced, and machining quality improved.

[0137] By predicting the radius of curvature and reducing machining errors, this method can help machine tool manufacturers optimize machining processes and improve production efficiency. Accurate predictions and a small error range can reduce the number of rework operations and adjustments, saving time and costs and increasing productivity.

[0138] By combining the geometric error fitting function with the positional error and profile error of the characteristic points of the bearing raceway cross-section curve, the machining quality can be better evaluated and quantitative advantages can be provided, enabling enterprises to discover and correct problems in the machining process more quickly.

[0139] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the machining error of the raceway curvature radius of a wind turbine bearing, characterized in that, Includes the following steps: S1. Based on the geometric structure of the heavy-duty vertical lathe, establish a geometric error transmission model of the heavy-duty vertical lathe using rigid body kinematics, and use rigid body kinematics to describe the error transmission law of the machine tool components. S2. Use a laser interferometer to measure the geometric error of the machine tool by extracting feature points; S3. Based on the error model and transformation matrix, the geometric errors are superimposed to obtain the position error of any point, and the position error and contour error between points are calculated. S4. Use a coordinate measuring machine to measure the radius of curvature of the raceway of the actual wind turbine bearing and compare it with the predicted value to verify the accuracy of the error prediction method. The geometry of the heavy-duty vertical lathe includes a bed and a worktable. The bed includes a column, a crossbeam, a horizontal slide, and a vertical slide. The lathe has four motion axes: the W axis of the crossbeam, the X axis of the horizontal slide, the Z axis of the vertical slide, and the C axis of the spindle worktable. The heavy-duty vertical lathe has six degrees of freedom in its motion direction for each moving part, and each degree of freedom will generate a corresponding geometric error under the constraint conditions. Geometric errors include three linear errors and three rotation angle errors. The three linear errors include one positioning error and two straightness errors; the three rotation angle errors include roll angle error, pitch angle error and yaw angle error. These geometric errors are called position-related geometric errors. The geometric error propagation model is established based on the deviations between various components of a heavy-duty vertical lathe; In step S2, for a wind turbine bearing with a raceway curvature radius R=26.9mm and a ball diameter D=50.8mm, the geometric error of any position of the moving part of the heavy-duty vertical lathe is obtained based on the established error model and error fitting formula. The feature points were extracted by taking 9 feature points at 5° intervals along the upper and lower raceway curves of the bearing raceway section. The horizontal slide X-axis travel range is [1196, 1208], and the vertical slide Z-axis travel range is [326, 374]. The unit of the travel range is millimeters.

2. The method for predicting the machining error of the raceway curvature radius of a wind turbine bearing according to claim 1, characterized in that: In step S3, the curve profile error refers to the amount of variation between the actual profile and the ideal profile of the curve, which is obtained from the position error.

3. The method for predicting the machining error of the raceway curvature radius of a wind turbine bearing according to claim 1, characterized in that: In step S4, the curvature radius of the raceway on the wind turbine bearing is selected for verification. Using a coordinate measuring machine, the measuring probe selects the raceway cross-sectional curves in four directions at 90-degree intervals along the circumference of the machined wind turbine bearing, and measures their curvature radii respectively to obtain the actual cross-sectional curve curvature radius of the raceway on the wind turbine bearing.

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