CN116720274A - Method for forming metal corrosion pit removing processing surface - Google Patents
Method for forming metal corrosion pit removing processing surface Download PDFInfo
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- 230000007797 corrosion Effects 0.000 title claims abstract description 56
- 238000005260 corrosion Methods 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000002184 metal Substances 0.000 title claims abstract description 26
- 238000003754 machining Methods 0.000 claims abstract description 40
- 238000005457 optimization Methods 0.000 claims abstract description 26
- 239000000654 additive Substances 0.000 claims abstract description 21
- 230000000996 additive effect Effects 0.000 claims abstract description 21
- 239000007921 spray Substances 0.000 claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 18
- 230000007547 defect Effects 0.000 claims description 24
- 230000008569 process Effects 0.000 claims description 14
- 230000008439 repair process Effects 0.000 abstract description 6
- 238000010288 cold spraying Methods 0.000 abstract 2
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- 230000009977 dual effect Effects 0.000 description 2
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Abstract
The application discloses a method for generating a metal corrosion pit removal machining surface, which comprises the steps of obtaining corrosion pit clouds on the surface of a metal to be repaired, and treating the corrosion pit clouds to obtain a point cloud section line and a point cloud guide line of the corrosion pit; constructing a parameterized basal plane of the corrosion pit; adjusting the parameterized base surface according to the point cloud section line and the point cloud guide line to generate an initial processing surface; and taking the coordinates of the control points in the initial processing surface as an optimization variable of the UG optimizer, taking the cold spray additive manufacturing requirement as an optimization constraint, taking the average value of the sum of the minimum distances from each point of the corrosion pit to the initial processing surface as an optimization objective function, and solving the control points of the initial processing surface by using the UG optimizer to carry out iterative adjustment to generate a final processing surface. The final machined surface obtained by the method not only meets the manufacturing process requirements of cold spraying additive, but also approximates to the shape of a corrosion pit, and shortens the repair time of the cold spraying additive of the part.
Description
Technical Field
The application relates to a method for generating a metal corrosion pit removing machining surface, which is convenient for repairing the metal corrosion pit by adopting a cold spray additive manufacturing technology.
Background
The aircraft casing is exposed to severe environmental conditions for a long time, surface corrosion is easy to occur, and the aircraft safety can be influenced when severe. The cold spray additive manufacturing technology can repair the surface of the casing. Before the cold spray additive manufacturing technology is adopted to repair the surface of the casing, a numerical control machine tool is required to remove the surface corrosion part, and a machining surface meeting the requirements of the cold spray additive manufacturing technology is formed. The numerical control machining needs to obtain the defect position of the surface of the casing and a machining surface digital model, generally adopts 3D scanning to obtain defect point cloud, and then generates a machining surface in UG software according to the defect point cloud. If the number of defects is relatively large, it takes a long time to generate the machined surface, resulting in low repair efficiency.
Disclosure of Invention
The application aims to provide a method for generating a metal corrosion pit removal machining surface, which is used for realizing rapid generation of a defect machining surface and improving repair efficiency.
The application solves the technical problems by the following technical scheme: a method for forming a metal corrosion pit removing machining surface comprises the following steps:
acquiring corrosion pit point clouds of the metal surface to be repaired, and processing the corrosion pit point clouds to obtain a point cloud section line and a point cloud guide line of the corrosion pit;
constructing a parameterized base surface of the corrosion pit, wherein the parameterized base surface is composed of a plurality of section lines and a plurality of guide lines;
adjusting the parameterized base surface according to the point cloud section line and the point cloud guide line to generate an initial processing surface;
and taking the coordinates of the control points in the initial processing surface as an optimization variable of the UG optimizer, taking the cold spray additive manufacturing requirement as an optimization constraint, taking the average value of the sum of the minimum distances from each point of the corrosion pit to the initial processing surface as an optimization objective function, and solving the control points of the initial processing surface by using the UG optimizer to carry out iterative adjustment to generate a final processing surface.
Further, the specific implementation process for processing the corrosion pit cloud is as follows:
performing cross-sectional treatment on the corrosion pit cloud to construct a corrosion pitNA bar point cloud cross section line;
connecting coordinate points of the non-etched surface to construct an edge point cloud guide line, and then constructing an intermediate point cloud guide line of the etched pit;
selection ofnStrip point cloud section linemA point cloud guide line is striped, and the selected point cloud section line and the point cloud guide line are output;
wherein the point cloud guide lines comprise edge point cloud guide lines and middle point cloud guide lines, and the number of the point cloud guide lines is less than or equal to 3n≤N，2≤m≤M，NFor the number of point cloud cross-sectional lines constructed,Mthe number of guidewires for the point cloud constructed.
Preferably, the specific implementation process of outputting the selected point cloud section line and the point cloud guide line is as follows:
acquiring a selected point cloud section line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the acquired point cloud section line through a UF_CURVE_create_point function to obtain the selected point cloud section line;
the method comprises the steps of obtaining a selected point cloud guide line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the obtained point cloud guide line through a UF_CURVE_create_point function to obtain the selected point cloud guide line.
Further, the specific implementation process of adjusting the parameterized base surface according to the point cloud section line and the point cloud guide line is as follows:
sequentially constructing a first set for each point cloud section line, and storing all control points of the point cloud section lines in the corresponding first set;
sequentially constructing a second set for each point cloud guide line, and storing all control points of the point cloud guide lines in the corresponding second set;
and after the control points of all the point cloud section lines and the control points of all the point cloud guide lines are stored, adjusting the parameterized base surface according to all the point cloud section lines and the control points of all the guide lines to generate an initial processing surface.
Further, the specific implementation process of adjusting the parameterized base surface according to the control points of all the point cloud section lines and all the guide lines is as follows:
each control point tag value of each point cloud section line is given to the control point tag value of the section line of the corresponding parameterized base surface in sequence, and the parameterized base surface is adjusted according to the control point tag value of the section line of the parameterized base surface;
each control point tag value of each point cloud guide line is sequentially assigned to the control point tag value of the guide line of the corresponding parameterized base surface, and the parameterized base surface is adjusted according to the control point tag value of the guide line of the parameterized base surface;
and comparing the parameterized base surfaces before and after adjustment, deleting unadjusted control points in the parameterized base surfaces after adjustment, and generating an initial machining surface, wherein the unadjusted control points comprise unadjusted control points of section lines and unadjusted control points of guide lines.
Preferably, the selection of the different control points of the different section lines and the different control points of the different point cloud section lines of the parameterized base surface is realized by using a dual for loop, the one-to-one correspondence of the control points of the section lines of the parameterized base surface and the control points of the point cloud section lines is realized, and the selection of the different control points of the different guide lines and the different control points of the different point cloud guide lines of the parameterized base surface is realized by using the dual for loop, so that the one-to-one correspondence of the control points of the guide lines of the parameterized base surface and the control points of the point cloud guide lines is realized.
Further, the optimization constraints include a maximum machining angle constraint, a section line concave constraint, and a section line containing all defect point cloud constraints.
Further, the maximum machining angle constraint is specifically:
acquiring an included angle between every two adjacent parting lines of each section line in the initial processing surface by using a UF_CURVE_ask_current_turn_angle function in NX Open C/ufun, and storing the included angle in a uf_mode_expression.h function;
creating a maximum processing angle function according to the uf_modl_expression.h function and the included angle stored in the uf_modl_expression.h function, so that the value of the uf_modl_expression.h function is smaller than the value of the maximum processing angle function;
the section line indent constraint is specifically:
acquiring a curvature center point of each control point of each section line in the initial processing surface, selecting a point P in a space contained in a corrosion pit, and calculating an included angle between each first connecting line and a second connecting line corresponding to the first connecting line to enable the included angle to be smaller than 90 degrees, wherein the first connecting line is a connecting line between a pointing point P and the section line control point in the initial processing surface, and the second connecting line is a connecting line between the control point and the curvature center point;
the cross section line comprises all defect point cloud constraints specifically as follows:
selecting a point P in a space contained in the corrosion pit, and calculating the length of each first line segment, wherein the first line segment is a connecting line between the point P of the pointing point and the point of the corrosion pit;
and calculating the length of a second line segment corresponding to the first line segment, so that the length of the first line segment is smaller than that of the second line segment, wherein the second line segment is a connecting line between the point P and the intersection point of the extension line of the first line segment and the initial machining surface.
Further, the specific expression of the optimization objective function is:
wherein ,d i first of corrosion pitsiThe minimum distance of the points to the initial working surface,Gfor the number of etch pits,f(d) The average value of the sum of the minimum distances from each point of the etch pit to the initial working surface is minimized.
Advantageous effects
Compared with the prior art, the application has the advantages that:
the method for generating the metal corrosion pit removing machining surface not only meets the requirements of a cold spray additive manufacturing process, but also can be close to the shape of the corrosion pit, thereby greatly shortening the time for repairing the cold spray additive of some parts and improving the repairing quality.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawing in the description below is only one embodiment of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method of forming a metal etch pit removal process surface in an embodiment of the application;
FIG. 2 is a graph of the results of the corrosion pit cloud data import UG in an embodiment of the present application;
FIG. 3 is a schematic view of a cross-sectional line of a point cloud in an embodiment of the application;
FIG. 4 is a schematic view of a point cloud guide line in an embodiment of the application;
FIG. 5 is a diagram of a secondary development control operation interface in an embodiment of the application;
FIG. 6 is a control point schematic of a point cloud cross-section line and a point cloud guide line in an embodiment of the application;
FIG. 7 is a schematic diagram of a parameterized base surface constructed in an embodiment of the present application;
FIG. 8 is a schematic view of several cross-sectional lines and guide lines of a parameterized base surface in an embodiment of the application;
FIG. 9 is a schematic view of an initial working surface (showing a defect point cloud) according to an embodiment of the present application;
FIG. 10 is an optimization setup operation interface in an embodiment of the application;
FIG. 11 is a schematic illustration of a cross-sectional line meeting cold spray additive manufacturing requirements in an embodiment of the present application;
FIG. 12 is a schematic diagram of a guide wire meeting cold spray additive manufacturing requirements in an embodiment of the application;
FIG. 13 is a schematic view of the angle of cross-sectional line indent constraint in an embodiment of the present application;
FIG. 14 is a schematic diagram of the length of a line segment with a cross-sectional line containing all defect point cloud constraints according to an embodiment of the present application;
FIG. 15 is a final machined surface (showing a defect point cloud) after optimization in an embodiment of the present application;
fig. 16 is a final machined surface (hidden defect point cloud) after optimization in an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made more apparent and fully by reference to the accompanying drawings, in which it is shown, however, only some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The technical scheme of the application is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
This example illustrates the effectiveness of the metal pit removal process surface generation method of the present application, taking a single pit defect as an example.
As shown in fig. 1, the method for forming a metal etch pit removal machining surface provided in this embodiment includes the following steps:
step 1: and acquiring the corrosion pit point cloud of the metal surface to be repaired, and processing the corrosion pit point cloud to obtain a point cloud section line and a point cloud guide line of the corrosion pit.
And scanning the metal surface to be repaired by using 3D scanning equipment (such as a laser scanner) to obtain corrosion pit cloud data. The corrosion pit cloud data is a collection of points under a coordinate system, is a three-dimensional digital expression of a metal surface structure to be repaired, is composed of a large number of scattered three-dimensional points, and can provide accurate three-dimensional coordinate information and various information such as strength, color and the like. The coordinate system of the corrosion pit cloud can be a laser scanner coordinate system, an inertial navigation coordinate system, a local horizontal coordinate system and a geocentric fixed coordinate system.
The origin O of the laser scanner coordinate system is a laser emission point, the X axis points to the advancing direction of the carrier, the Y axis is vertical upwards, and the Z axis is vertical to the X axis, so that a right-hand system is formed. The origin O of the inertial navigation coordinate system is the inertial platform reference center, the coordinate system is defined according to the inertial platform internal reference frame, the Y axis points to the longitudinal axis of the carrier forwards, the advancing direction of the carrier is the X axis to the right, and the Z axis vertically upwards forms a right hand system. The origin of the local horizontal coordinate system is positioned at the GNSS phase center, the X axis points to the east, the Y axis points to the true north, and the Z axis forms a right hand system along the normal direction of the ellipsoid; according to different coordinate axis directions, the local horizontal coordinate system can be selected as a right-hand coordinate system such as northeast, northwest, western and the like, and different selection modes are mainly related to application scenes. The geocentric geodetic coordinate system, which is abbreviated as geodetic coordinate system, is a geodetic coordinate system with geodetic as origin, origin O is the earth centroid, Z axis points to north pole in parallel with the earth axis, X axis points to the intersection point of the original meridian and equator, and Y axis is perpendicular to XOZ plane (i.e. the intersection point of east 90 ° and equator) to form the right hand coordinate system.
The UG optimizer can import point cloud data in different formats, so that corrosion pit point clouds are directly imported in the UG optimizer (the importing result is shown in fig. 2), and the corrosion pit point clouds are processed to obtain a point cloud section line and a point cloud guide line of the corrosion pit, wherein the specific processing process is as follows:
step 1.1: cross-sectional treatment of the etch pit cloud to build etch pitsNA bar point cloud cross section line, as shown in fig. 3;
step 1.2: connecting coordinate points of the non-etched surface, constructing an edge point cloud guide line, and then constructing an intermediate point cloud guide line of the etched pit, as shown in fig. 4;
step 1.3: selection ofnStrip point cloud section linemAnd outputting the selected point cloud section line and the point cloud guide line. Wherein the point cloud guide lines comprise edge point cloud guide lines and middle point cloud guide lines, and the number of the point cloud guide lines is less than or equal to 3n≤N，2≤m≤M，NFor the number of point cloud cross-sectional lines constructed,Mthe number of guidewires for the point cloud constructed.
In this embodiment, control selection by secondary development in UGnStrip point cloud section linemThe stripe point cloud guides the line, the operation interface of the secondary development control is shown in figure 5, and the output result is shown in figure 6。
Specifically, the specific process of the secondary development control output control point is as follows:
acquiring a selected point cloud section line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the acquired point cloud section line through a UF_CURVE_create_point function to obtain the selected point cloud section line; the method comprises the steps of obtaining a selected point cloud guide line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the obtained point cloud guide line through a UF_CURVE_create_point function to obtain the selected point cloud guide line.
Step 2: a parameterized floor of the etch pit is constructed.
In the UG software, a parameterized floor of the etch pit is pre-established, as shown in fig. 7. The parameterized base surface comprises a number of section lines and a number of guide lines, each section line or guide line being constituted by a control point, as shown in fig. 8, the parameterized base surface being stored in a certain document path.
Step 3: and adjusting the parameterized base surface according to the point cloud section line and the point cloud guide line to generate an initial processing surface.
The control points of the point cloud section line and the control points of the point cloud guide line need to be both stored in a collection before the parameterized base surface is adjusted according to the point cloud section line and the point cloud guide line. Specifically, a first set is built for each point cloud section line in sequence, and all control points of the point cloud section lines are stored in the corresponding first set; and constructing a second set for each point cloud guide line in sequence, and storing all control points of the point cloud guide lines in the corresponding second set.
By way of example only, and not by way of limitation,n=4，m=3, i.e. step 1 results in 4 point cloud cross-sectional lines and 3 point cloud guide lines, each point cloud cross-sectional line corresponding to a first set expressed as，i=1,2,3,4，P ik Is the firstiFirst of cross section line of strip point cloudkThe number of control points at which the control points,n i is the firstiControl points of the cross section line of the strip point cloud; similarly, the second set corresponding to each point cloud guide line is expressed as +.>，j=1,2,3，P jk Is the firstjPoint cloud guide line NokThe number of control points at which the control points,m j is the firstjControl points of the bar point cloud guide line.
Assuming that the 4 point cloud section lines obtained in the step 1 are 4 section lines shown in fig. 3, constructing a first set and storing control points for each point cloud section line in sequence specifically includes: and constructing a first set for a first point cloud section line on one side (such as the left side or the right side), sequentially storing all control points of the first point cloud section line in the first set, constructing a second first set for a second point cloud section line on the side, sequentially storing all control points of the second point cloud section line in the second first set, constructing a third first set for a third point cloud section line, sequentially storing all control points of the third point cloud section line in the third first set, finally constructing a fourth first set for a fourth point cloud section line, sequentially storing all control points of the fourth point cloud section line in the fourth first set, and finishing the construction of the first sets of all point cloud section lines and the storage of the control points. The construction of the second set of point cloud guidewires and the storage of control points are the same.
In this embodiment, the control points of each point cloud section line are sequentially selected through the secondary development control, then the control points of each point cloud guide line are sequentially selected, and it is noted that after storing the control points of each point cloud section line or each point cloud guide line into a corresponding first set or second set, the selection of the control points of the next point cloud section line or point cloud guide line is performed until the storage of all the point cloud section lines and the control points of all the point cloud guide lines is completed, so that the number of the first sets is equal to the number of the point cloud section lines, and the number of the second sets is equal to the number of the point cloud guide lines. And then, selecting a parameterized base plane to generate an initial machining surface for removing the metal corrosion pits, wherein a specific operation interface is shown in fig. 5, and the generated initial machining surface is shown in fig. 9, and it is obvious from fig. 9 that the initial machining surface does not contain all defect point clouds, namely, the requirements of cold spray additive manufacturing are not met.
And based on the first set and the second set, the parameterized base surface is selected again to generate an initial machining surface, namely, the parameterized base surface is adjusted according to all the point cloud cross section lines and all the control points of the guide lines so as to generate the initial machining surface. The specific adjustment process of the parameterized base surface comprises the following steps:
step 3.1: each control point tag value of each point cloud section line is given to the control point tag value of the section line of the corresponding parameterized base surface in sequence, and the parameterized base surface is adjusted according to the control point tag value of the section line of the parameterized base surface;
step 3.2: each control point tag value of each point cloud guide line is sequentially assigned to the control point tag value of the guide line of the corresponding parameterized base surface, and the parameterized base surface is adjusted according to the control point tag value of the guide line of the parameterized base surface;
step 3.3: and comparing the parameterized base surfaces before and after adjustment, deleting unadjusted control points in the parameterized base surfaces after adjustment, and generating an initial machining surface, wherein the unadjusted control points comprise unadjusted control points of section lines and unadjusted control points of guide lines.
In order to automatically select different control points of different section lines or different control points of different guide lines of the parameterized base surface, a double for loop is used to achieve the selection of control points of the parameterized base surface. Taking as an example the control point of the section line of the parameterized base plane: the outer layer for circularly controlling the number of the section lines of the parameterized base surface, and the number of the circulation times of the outer layer for circularly is equal to the number of the section lines of the point cloud in order to realize the adjustment of the section lines of the parameterized base surface by the section lines of the point cloud; the circulation body of the outer layer for circulation is the inner layer for circulation, the inner layer for circulation controls the control point quantity of the cross section line of the parameterization base surface, in order to realize the adjustment of the control point of each point cloud cross section line to the control point of the corresponding cross section line, the circulation number of the inner layer for circulation is equal to the control point quantity of the cross section line of the current parameterization base surface (namely, the cross section line of the parameterization base surface being executed by the outer layer for circulation), and the circulation body of the inner layer for circulation is to assign the control point tag value of the point cloud cross section line to the control point tag value of the cross section line of the parameterization base surface, namely, the control point of the point cloud cross section line replaces the control point of the cross section line of the parameterization base surface.
In the specific implementation process, a two-dimensional array is constructed for the parameterized base surfaceD H×L ，HThe number of the section lines of the parameterized basal plane is%HEqual to the number of point cloud cross-sectional lines),Lthe number of control points for the section line of each parameterized base surfaceLEqual to the number of control points of the point cloud cross section line), the first of the parameterized base surfaces is set in a particular positional orderhFirst of strip section linelThe tag values of the control points are stored in a two-dimensional arrayD H×L Wherein, among them,h=1,2,…,H，l=1,2,…,Lthe specific position sequence is to store the control point tag value of the section line of the first parameterized base surface at one side, store the control point tag value of the section line of the second parameterized base surface at the other side, and so on until the completionHAnd (5) storing the control point tag value of the section line of the strip parameterized base surface. For etch pits, a two-dimensional array is constructedE C×B ，CThe number of the point cloud section lines of the corrosion pitHEqual toC），BThe number of control points of the cross section line of each point cloudLEqual toB) According to the specific position sequencecFirst of cross section line of strip point cloudbThe tag values of the control points are stored in a two-dimensional arrayE C×B Wherein, among them,c=1,2,…,C，b=1,2,…,B. The specific position sequence is to store the control point tag value of the first point cloud section line at one side, store the control point tag value of the second point cloud section line at the other side, and so on until the completionCAnd storing the control point tag value of the cross section line of the strip point cloud. Storing the point cloud section line into a two-dimensional arrayE C×B Is stored in two-dimensional data with the order of the parameterized base surface and the cross-sectional line of the parameterized base surfaceD H×L Is the same in order. Thus, the circulation body of the inner layer for circulation isD[i-1][j-1]=E[i-1][j-1]I.e. when proceeding to the firstiSecondary outer layer for circulationIs the first of (2)jThe second inner layer for circulation, the firstiFirst of cross section line of strip point cloudjThe tag value of each control point is transmitted to the firstiStrip parameterization of basal cross-section linejAnd controlling the tag value of the point so as to realize the correspondence of the point cloud section line and the parameterized base plane section line. The control point tag value of each point cloud section line is transmitted to the control point tag value of the section line of the parameterized base surface, and the coordinate value of the control point of the section line of the parameterized base surface is changed along with the change of the control point tag value of the section line of the parameterized base surface. And similarly, adjusting the control point tag value of the guide line of the parameterized base surface by utilizing each control point tag value of all the point cloud guide lines, and realizing adjustment of the control point coordinate value of the guide line of the parameterized base surface.
The adjustment of the control point coordinate values of all section lines of the parameterized base surface can be realized through double for circulation; and similarly, adjusting control point coordinate values of all guide lines of the parameterized base surface by using control points of the point cloud guide lines in a double-for cyclic utilization mode, and realizing adjustment of the parameterized base surface, wherein the parameterized base surface after adjustment is the initial machining surface.
Because the constructed parameterized base surface and one control point are changed, the related lines and planes are changed, but because the established parameterized base surface has more control points, not all control points are adjusted, the adjusted parameterized base surface is not the initial processing surface, therefore, the coordinates of the control points of the parameterized base surface after adjustment and the parameterized base surface before adjustment are compared in a traversing mode, the control points which are not adjusted are found out in the parameterized base surface after adjustment and deleted, and only the control points after adjustment are reserved, so that the initial processing surface is obtained.
Step 4: and taking the coordinates of the control points in the initial processing surface as an optimization variable of the UG optimizer, taking the cold spray additive manufacturing requirement as an optimization constraint, taking the average value of the sum of the minimum distances from each point of the corrosion pit to the initial processing surface as an optimization objective function, and solving the control points of the initial processing surface by using the UG optimizer to carry out iterative adjustment to generate a final processing surface.
Setting optimization variables, optimization constraints and optimization objective functions in UG software, and completing optimization setting, wherein an operation interface of the optimization setting is shown in FIG. 10.
In terms of cold spray additive manufacturing requirements, the cross-sectional line of the finished face should meet the cold spray additive manufacturing requirements, as shown in fig. 11. The cold spray additive manufacturing requirements mainly comprise the maximum processing angle, the section line should meet the concave requirement (namely the section line concave constraint) and the section line should contain all defect points (namely the section line contains all defect point cloud constraint). Too large a machining angle or protruding outside the section line can affect the effect of cold spray additive repair.
The cold spray additive manufacturing requirements that the guideline of the final machined surface should meet, as shown in fig. 12, should contain all defect points and the established final machined surface should be on the side of the defect point cloud, i.e. contain all defect point clouds.
In the specific implementation process, the maximum processing angle constraint is specifically: directly obtaining an included angle alpha between every two adjacent parting lines of each section line in an initial processing surface by using a UF_CURVE_ask_current_turn_angle function in NX Open C/ufun, and storing the included angle alpha in a uf_mode_expression.h function; and creating a maximum machining angle function according to the uf_mod_expression.h function and the included angle stored in the uf_mod_expression.h function, so that the value of the uf_mod_expression.h function is smaller than the value of the maximum machining angle function, which is a constraint condition of the maximum machining angle.
The section line indent constraint is specifically: the curvature center point of each control point of each section line in the initial processing surface is obtained, one point P in the space contained in the corrosion pit is selected, and the included angle between each first connecting line and the second connecting line corresponding to the first connecting line is calculated, so that the included angle beta is smaller than 90 degrees, and the constraint condition of concave section lines is met. Wherein the first connecting line is a control point of the middle section line of the pointing point P and the initial processing surfaceP 1 The second connection refers to the control pointP 1 And control pointP 1 Corresponding center point of curvatureP 1 ’ The connection between them is shown in fig. 13. Each control point of each section line has its center point of curvature, so that each control point of each section line needs to satisfy the section line indent constraint, i.e., the first and second linksThe number of lines is equal to the sum of all control points of all section lines of the initial machining surface.
The section line contains all defect point cloud constraints specifically: selecting a point P in the space contained in the etch pit, calculating the length L of each first line segment by using a series of correlation functions related to UF_CURVE and uf_modl_expression.h in NX Open C/ufun 1 The method comprises the steps of carrying out a first treatment on the surface of the Then calculate the length L of the second line segment corresponding to the first line segment 2 Length L of the first line segment 1 Length L smaller than the second line segment 2 . Wherein the first line segment is a line between the point P and the control point of the cross-sectional line in the initial processing surface, and the second line segment is a line between the point P and the intersection point of the extension line of the first line segment and the initial processing surface, as shown in fig. 14. Therefore, the constraint condition that the final machining surface contains all defect point clouds is ensured, and the constraint condition that the cross section line and the guide line of the final machining surface contain all defect points is also met.
The maximum working angle function, the section line indent constraint of less than 90 ° are all set in the operation interface of fig. 10, and a point P in the space contained in the etch pit is directly completed in the graphic window of UG.
In the embodiment, the average value of the sum of the minimum distances from each point of the corrosion pit to the initial machining surface is minimum as an optimization objective function, and the specific expression of the optimization objective function is as follows:
wherein ,d i first of corrosion pitsiThe minimum distance of the points to the initial working surface,Gfor the number of etch pits,f(d) The average value of the sum of the minimum distances from each point of the etch pit to the initial working surface is minimized.
And submitting the solution in the UG optimizer, automatically performing iterative adjustment of control point parameters of the primary processing surface, and generating a final processing surface meeting the cold spray additive manufacturing requirements, as shown in fig. 15 and 16, so as to achieve the aim of quickly generating the defect processing surface.
The foregoing disclosure is merely illustrative of specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art will readily recognize that changes and modifications are possible within the scope of the present application.
Claims (9)
1. A method for forming a metal etch pit removal machining surface, comprising the steps of:
acquiring corrosion pit point clouds of the metal surface to be repaired, and processing the corrosion pit point clouds to obtain a point cloud section line and a point cloud guide line of the corrosion pit;
constructing a parameterized base surface of the corrosion pit, wherein the parameterized base surface is composed of a plurality of section lines and a plurality of guide lines;
adjusting the parameterized base surface according to the point cloud section line and the point cloud guide line to generate an initial processing surface;
and taking the coordinates of the control points in the initial processing surface as an optimization variable of the UG optimizer, taking the cold spray additive manufacturing requirement as an optimization constraint, taking the average value of the sum of the minimum distances from each point of the corrosion pit to the initial processing surface as an optimization objective function, and solving the control points of the initial processing surface by using the UG optimizer to carry out iterative adjustment to generate a final processing surface.
2. The method for forming a metal etch pit removal machining surface according to claim 1, wherein the specific implementation process of treating the etch pit cloud is:
performing cross-sectional treatment on the corrosion pit cloud to construct a corrosion pitNA bar point cloud cross section line;
connecting coordinate points of the non-etched surface to construct an edge point cloud guide line, and then constructing an intermediate point cloud guide line of the etched pit;
selection ofnStrip point cloud section linemA point cloud guide line is striped, and the selected point cloud section line and the point cloud guide line are output;
wherein the point cloud guideline comprises an edge point cloud guideline and an intermediatePoint cloud guide line of less than or equal to 3 percentn≤N，2≤m≤M，NFor the number of point cloud cross-sectional lines constructed,Mthe number of guidewires for the point cloud constructed.
3. The method for generating a metal etch pit removal machining surface according to claim 2, wherein the specific implementation process of outputting the selected point cloud cross-sectional line and point cloud guide line is:
acquiring a selected point cloud section line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the acquired point cloud section line through a UF_CURVE_create_point function to obtain the selected point cloud section line;
the method comprises the steps of obtaining a selected point cloud guide line through a UF_EVAL_ask_spline_control_pts spline function in NX Open C/ufun, and then creating control points of the obtained point cloud guide line through a UF_CURVE_create_point function to obtain the selected point cloud guide line.
4. The method for forming a metal etch pit removal machining surface according to claim 1, wherein the specific implementation procedure of adjusting the parameterized base surface according to the point cloud cross-section line and the point cloud guide line is:
sequentially constructing a first set for each point cloud section line, and storing all control points of the point cloud section lines in the corresponding first set;
sequentially constructing a second set for each point cloud guide line, and storing all control points of the point cloud guide lines in the corresponding second set;
and after the control points of all the point cloud section lines and the control points of all the point cloud guide lines are stored, adjusting the parameterized base surface according to all the point cloud section lines and the control points of all the guide lines to generate an initial processing surface.
5. The method for forming a machined surface for removing metal etch pits according to claim 4, wherein the adjusting the parameterized base surface according to control points of all point cloud cross-section lines and all guide lines is performed by:
each control point tag value of each point cloud section line is given to the control point tag value of the section line of the corresponding parameterized base surface in sequence, and the parameterized base surface is adjusted according to the control point tag value of the section line of the parameterized base surface;
each control point tag value of each point cloud guide line is sequentially assigned to the control point tag value of the guide line of the corresponding parameterized base surface, and the parameterized base surface is adjusted according to the control point tag value of the guide line of the parameterized base surface;
and comparing the parameterized base surfaces before and after adjustment, deleting unadjusted control points in the parameterized base surfaces after adjustment, and generating an initial machining surface, wherein the unadjusted control points comprise unadjusted control points of section lines and unadjusted control points of guide lines.
6. The method according to claim 5, wherein the selection of the different control points of the different cross-section lines and the different control points of the different point cloud cross-section lines of the parameterized base surface is achieved by a double-for loop, the one-to-one correspondence of the control points of the cross-section lines of the parameterized base surface and the control points of the point cloud cross-section lines is achieved, and the selection of the different control points of the different guide lines and the different control points of the different point cloud guide lines of the parameterized base surface is achieved by a double-for loop.
7. The method for generating a metal etch pit removal machining surface according to any one of claims 1 to 6, wherein the optimization constraints include a maximum machining angle constraint, a section line indent constraint, and a section line including all defect point cloud constraints.
8. The method for forming a machined surface for metal etch pit removal of claim 7, wherein the maximum machining angle constraint is specifically:
acquiring an included angle between every two adjacent parting lines of each section line in the initial processing surface by using a UF_CURVE_ask_current_turn_angle function in NX Open C/ufun, and storing the included angle in a uf_mode_expression.h function;
creating a maximum processing angle function according to the uf_modl_expression.h function and the included angle stored in the uf_modl_expression.h function, so that the value of the uf_modl_expression.h function is smaller than the value of the maximum processing angle function;
the section line indent constraint is specifically:
acquiring a curvature center point of each control point of each section line in the initial processing surface, selecting a point P in a space contained in a corrosion pit, and calculating an included angle between each first connecting line and a second connecting line corresponding to the first connecting line to enable the included angle to be smaller than 90 degrees, wherein the first connecting line is a connecting line between a pointing point P and the section line control point in the initial processing surface, and the second connecting line is a connecting line between the control point and the curvature center point;
the cross section line comprises all defect point cloud constraints specifically as follows:
selecting a point P in a space contained in the corrosion pit, and calculating the length of each first line segment, wherein the first line segment is a connecting line between the point P of the pointing point and the point of the corrosion pit;
and calculating the length of a second line segment corresponding to the first line segment, so that the length of the first line segment is smaller than that of the second line segment, wherein the second line segment is a connecting line between the point P and the intersection point of the extension line of the first line segment and the initial machining surface.
9. The method for forming a metal etch pit removal machining surface according to claim 1, wherein the specific expression of the optimization objective function is:
wherein ,d i first of corrosion pitsiThe minimum distance of the points to the initial working surface,Gfor the number of etch pits,f (d) The average value of the sum of the minimum distances from each point of the etch pit to the initial working surface is minimized.
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