CN110069041B - Workpiece machining method and system based on-machine measurement - Google Patents
Workpiece machining method and system based on-machine measurement Download PDFInfo
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- CN110069041B CN110069041B CN201810068753.4A CN201810068753A CN110069041B CN 110069041 B CN110069041 B CN 110069041B CN 201810068753 A CN201810068753 A CN 201810068753A CN 110069041 B CN110069041 B CN 110069041B
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/4097—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by using design data to control NC machines, e.g. CAD/CAM
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
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Abstract
The invention provides a workpiece processing method and a workpiece processing system based on-machine measurement, wherein the workpiece processing method comprises the following steps: measuring the geometric data of the processing surface of the workpiece in an on-machine measuring mode, registering and adjusting the geometric data according to the geometric data and a preset ideal workpiece model to obtain the geometric registration data of the processing surface, compensating and correcting a numerical control processing program of the workpiece according to the geometric registration data, and processing the workpiece by using a numerical control processing program after compensation and correction. According to the scheme provided by the invention, the workpiece can be subjected to self-adaptive machining based on the workpiece geometric dimension data measured on machine, and the qualification rate and the machining efficiency of the machined workpiece are improved.
Description
Technical Field
The invention relates to the field of numerical control machining, in particular to a workpiece machining method and system based on-machine measurement.
Background
Currently, there are a large number of large, complex and difficult to machine parts in the aerospace, automotive, marine, etc. fields. In the processing process of the parts, the qualification rate and the processing efficiency of the parts are lower due to factors such as processing deformation, inaccurate clamping, cutter abrasion, uneven allowance, equipment load change and the like. With the rapid development of the digital measurement technology, the three-dimensional digital information of the processing state of a workpiece (namely a part) can be obtained by adopting a certain on-machine measurement technology, and the processing strategy can be adaptively changed by a machine tool according to the measured processing state of the workpiece through the adaptive processing technology.
In the prior art, the qualification rate and the processing efficiency of the workpiece are not only related to the processing state of the workpiece, but also often related to the geometric dimension of the workpiece, but the qualification rate and the processing efficiency of the workpiece are low because the geometric dimension of the workpiece is not considered in the conventional workpiece processing method.
Disclosure of Invention
The embodiment of the invention provides a workpiece processing method and system based on-machine measurement, which can be used for carrying out self-adaptive processing on a workpiece based on geometric size data of the workpiece measured on-machine, and improving the qualification rate and the processing efficiency of the workpiece.
In a first aspect, an embodiment of the present invention provides a workpiece processing method based on-machine measurement, including:
measuring the geometric data of the processing surface of the workpiece by using an on-machine measuring mode;
according to the geometric data and a preset ideal workpiece model, carrying out registration adjustment on the geometric data to obtain geometric registration data of the machining surface;
according to the geometric registration data, compensating and correcting a numerical control machining program of the workpiece;
and processing the workpiece by using the compensated and corrected numerical control processing procedure.
Optionally, the measuring the geometric data of the processing surface of the workpiece by using an on-machine measurement mode includes:
and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode.
Optionally, the registering and adjusting the geometric data according to the geometric data and a preset ideal workpiece model to obtain geometric registration data of the machining surface includes:
dispersing the preset ideal workpiece model into point cloud data based on an STL format, and extracting coordinate data of a triangular control vertex in a corresponding STL file;
based on a principal component analysis method, respectively calculating covariance matrixes of the extracted control vertexes and actually measured point clouds corresponding to the geometric data according to the following formula;
solving the covariance matrix, and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
based on an iterative closest point algorithm, rigid body transformations R and T which enable the f value to be minimum and are under the following constraint conditions are calculated;
performing registration adjustment on the initial registration data by using the R and the T to obtain the geometric registration data;
wherein n is the number of the control vertexes or the actually measured point clouds, xiIs the abscissa of the control vertex or the measured point cloud,
is the mean, y, of the abscissas of the control vertices or the measured point cloudiIs the ordinate of the control vertex or the measured point cloud,
is the mean value of the vertical coordinates, p, of the control vertex or the measured point cloudiAs coordinate data of said control vertices, qiAnd initial registration data corresponding to the actually measured point cloud.
Optionally, if the geometric data of the processing surface of the workpiece is measured in a contact-type on-machine measurement manner, where the geometric data is coordinate data of a feature point on the processing surface, the performing compensation and correction on the numerical control processing program of the workpiece according to the geometric registration data includes:
according to the geometric registration data, carrying out inverse calculation on a NURBS curve by using a NURBS reconstruction theory, and carrying out forward calculation on the NURBS curve to obtain coordinate data of points on the NURBS curve corresponding to the cutter location point;
and correcting the coordinate data of the tool location point in the tool path file by using an inverse deformation method according to the coordinate data of the point corresponding to the tool location point on the NURBS curve and the coordinate data of the tool location point in the tool path file, and generating an NC code with compensation.
Optionally, if the geometric data of the processing surface of the workpiece is measured in a non-contact on-machine measurement manner, the performing compensation and correction on the numerical control processing program of the workpiece according to the geometric registration data includes:
according to the geometric registration data, carrying out NURBS curved surface reconstruction on the machined profile by using an inverse deformation method, and calculating a tool path by using the reconstructed NURBS curved surface;
and correcting the corresponding tool path file according to the calculated tool position track to generate an NC code with compensation.
In a second aspect, an embodiment of the present invention further provides an on-machine measurement based workpiece processing system, including:
the data measurement module is used for measuring the geometric data of the processing surface of the workpiece in an on-machine measurement mode;
the registration adjustment module is used for carrying out registration adjustment on the geometric data according to the geometric data and a preset ideal workpiece model to obtain geometric registration data of the machining surface;
the compensation correction module is used for compensating and correcting the numerical control machining program of the workpiece according to the geometric registration data;
and the numerical control processing module is used for processing the workpiece by using the compensated and corrected numerical control processing program.
Optionally, the data measurement module is specifically configured to:
and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode.
Optionally, the registration adjustment module includes:
the extraction unit is used for dispersing the preset ideal workpiece model into point cloud data based on the STL format and extracting coordinate data of a triangular control vertex in a corresponding STL file;
the first calculation unit is used for calculating covariance matrixes of the extracted control vertexes and the actually measured point clouds corresponding to the geometric data respectively according to the following formulas based on a principal component analysis method;
the first registration unit is used for solving the covariance matrix and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
a second calculation unit for calculating rigid body transformations R and T that minimize the f-value, based on an iterative closest point algorithm, of the following constraint conditions;
a second registration unit, configured to perform registration adjustment on the initial registration data by using the R and the T to obtain the geometric registration data;
wherein n is the number of the control vertexes or the actually measured point clouds, xiIs the abscissa of the control vertex or the measured point cloud,
is the mean, y, of the abscissas of the control vertices or the measured point cloudiIs the ordinate of the control vertex or the measured point cloud,
is the mean value of the vertical coordinates, p, of the control vertex or the measured point cloudiAs coordinate data of said control vertices, qiIs a stand forAnd initial registration data corresponding to the actually measured point cloud.
Optionally, if the geometric data of the processing surface of the workpiece is measured in a contact-type on-machine measurement manner, the geometric data is coordinate data of a feature point on the processing surface, and the compensation correction module includes:
the third calculation unit is used for carrying out inverse calculation on the NURBS curve by utilizing a NURBS reconstruction theory according to the geometric registration data and carrying out forward calculation on the NURBS curve to obtain coordinate data of points corresponding to the tool location points on the NURBS curve;
and the first correcting unit is used for correcting the coordinate data of the tool location point in the tool path file by using an inverse deformation method according to the coordinate data of the point corresponding to the tool location point on the NURBS curve and the coordinate data of the tool location point in the tool path file, and generating an NC code with compensation.
Optionally, if the geometric data of the processing surface of the workpiece is measured by using a non-contact on-machine measurement method, the compensation correction module includes:
the fourth calculation unit is used for carrying out NURBS curved surface reconstruction on the machined profile by using an inverse deformation method according to the geometric registration data and calculating a tool path by using the reconstructed NURBS curved surface;
and the second correcting unit is used for correcting the corresponding tool path file according to the calculated tool position track and generating an NC code with compensation.
According to the workpiece processing method provided by the embodiment of the invention, the geometric data of the processing surface of the workpiece is measured in an on-machine measurement mode, the geometric data of the processing surface is used for compensating and correcting the numerical control processing program, and the workpiece is processed by the numerical control processing program after compensation and correction, so that the workpiece can be subjected to self-adaptive processing based on the geometric size data of the workpiece measured on-machine, and the qualified rate and the processing efficiency of the processed workpiece are improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
FIG. 1 is a flow chart of a method of workpiece processing based on-machine measurements according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a contact on-machine measurement according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a non-contact on-machine measurement according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a reverse deformation method according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an on-machine metrology based workpiece processing system according to an embodiment of the present invention;
fig. 6 is a process flow diagram of an on-machine metrology based workpiece processing system in accordance with an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a workpiece processing method based on-machine measurement, including the following steps:
step 101: and measuring the geometric data of the processing surface of the workpiece by using an on-machine measuring mode.
In the embodiment of the present invention, the method for measuring the geometric data of the processing surface of the workpiece by using the on-machine measurement method may specifically be: and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode. In the contact-type on-machine measurement, for example, a machine tool stylus is used for measurement, and geometric data of a characteristic point on a machining surface is measured, for example, referring to fig. 2, when the machining surface is a sinking window, the geometric data of the characteristic point on the sinking window can be measured by using the machine tool stylus. Non-contact on-machine measurement is, for example, measurement using a three-dimensional laser scanner, which measures the geometric data of the machining surface, such as the sagging window, as shown in fig. 3, when the machining surface is the sagging window, the geometric data of the sagging window can be directly measured using the three-dimensional laser scanner.
It should be noted that the geometric data referred to herein is specifically three-dimensional coordinate data of feature points or actually measured point clouds on the processing surface. According to the processing requirement, the geometric data of the processing surface of a workpiece can be measured by using a contact-type on-machine measuring mode and a non-contact-type on-machine measuring mode simultaneously.
Step 102: and carrying out registration adjustment on the geometric data according to the geometric data and a preset ideal workpiece model to obtain geometric registration data of the machined surface.
The preset ideal workpiece model is, for example, a preset ideal CAD model. When the collected geometric data of the machining surface of the workpiece is subjected to registration adjustment, registration analysis under the constraint of allowance and tolerance can be performed on the basis of the measured data and the discrete cloud point data of the preset ideal CAD model, and the machining benchmark adjustment is completed.
Step 103: and according to the geometric registration data, compensating and correcting the numerical control machining program of the workpiece.
Specifically, when geometric data of a machined surface is measured in a contact-type on-machine measurement mode, error compensation can be performed based on a tool path file method, that is, NURBS (non-uniform Rational B-Spline) reconstruction of a machined surface is performed based on actually measured characteristic point data, the size and direction of errors of corresponding tool positions in a tool path file are calculated, coordinate data of corresponding tool positions in the tool path file are modified and post-processed, and an NC code with compensation is generated. When the geometric data of the processing surface is measured by using a non-contact on-machine measuring mode, error compensation can be carried out based on processing profile reconstruction, namely, firstly, the measured point cloud data is subjected to preprocessing such as filtering and simplification, then, the processing profile is reconstructed based on an inverse deformation method, and finally, the numerical control processing program is recalculated based on the reconstructed processing profile.
Step 104: and processing the workpiece by using the compensated and corrected numerical control processing procedure.
According to the workpiece processing method provided by the embodiment of the invention, the geometric data of the processing surface of the workpiece is measured in an on-machine measurement mode, the geometric data of the processing surface is used for compensating and correcting the numerical control processing program, and the workpiece is processed by the numerical control processing program after compensation and correction, so that the workpiece can be subjected to self-adaptive processing based on the geometric size data of the workpiece measured on-machine, and the qualified rate and the processing efficiency of the processed workpiece are improved.
In the embodiment of the invention, according to the geometric data of the machined surface obtained by measurement and the preset ideal workpiece model, the registration adjustment is carried out on the geometric data, and the process of obtaining the corresponding geometric registration data can be as follows:
firstly, discretely presetting an ideal workpiece model as point cloud data based on an STL format, and extracting coordinate data of a triangular control vertex in a corresponding STL file;
secondly, on the basis of a principal component analysis method, respectively calculating covariance matrixes of the extracted control vertexes and actually-measured point clouds (or characteristic points during contact measurement) corresponding to the geometric data according to the following formulas;
wherein n is the number of control vertexes or actually measured point clouds, xiTo control the abscissa of the apex or measured point cloud,
to control the mean, y, of the abscissas of the vertex or measured point cloudiTo control the vertical coordinate of the vertex or measured point cloud,
the mean value of the vertical coordinates of the control vertex or the measured point cloud.
It should be noted that, in the covariance matrix C,
and
and (7) corresponding.
Thirdly, solving the covariance matrix, and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
it should be noted that the solution result of solving the covariance matrix is three eigenvectors corresponding to the covariance matrix. In this way, when the initial registration adjustment is performed on the geometric data according to the solving result, the coordinate system 1 can be reconstructed based on three eigenvectors obtained by solving the covariance matrix corresponding to the control vertex, and the coordinate system 2 can be reconstructed based on three eigenvectors obtained by solving the covariance matrix corresponding to the actually measured point cloud; then calculating a rigid body transformation matrix of the coordinate system 2 relative to the coordinate system 1; and finally, transforming the geometric data according to the calculated rigid body transformation matrix to finish the initial registration adjustment process.
Then, based on an iterative closest point algorithm (PCA), rigid body transformations R and T which minimize the f value of the following constraint conditions are calculated;
wherein n is the number of control vertexes or actually measured point clouds, piTo control the coordinate data (x) of the verticesi，yi，zi)，qiInitial registration data (x) corresponding to the measured point cloudi，yi，zi)。
And finally, performing registration adjustment on the initial registration data by utilizing R and T to obtain geometric registration data.
Therefore, by means of the initial registration process and the accurate registration process, the adjustment of the processing reference can be completed, and the accuracy of the subsequent error calculation process is improved.
In the embodiment of the present invention, for the geometric data of the processing surface measured by using the contact on-machine measurement method, the geometric data is coordinate data of a feature point on the processing surface, and according to the corresponding geometric registration data, the process of performing compensation and correction on the numerical control processing program of the workpiece may be:
firstly, according to the geometric registration data, carrying out inverse calculation on a NURBS curve by using a NURBS reconstruction theory, and carrying out forward calculation on the NURBS curve to obtain coordinate data of points on the NURBS curve corresponding to the cutter location point;
and then, according to the coordinate data of the point corresponding to the tool position point on the NURBS curve and the coordinate data of the tool position point in the tool path file, correcting the coordinate data of the tool position point in the tool path file by using an inverse deformation method, and generating an NC code with compensation.
When NURBS curve back calculation is carried out by using NURBS reconstruction theory, if the geometric registration data of the actually measured characteristic points are recorded as qi(i ═ 0,1, ·, m), where m is the number of measured feature points, then the node vector u corresponding to the respective NURBS curve can be determined first, where u is0＝u1＝…＝uk＝0，un+1＝un+2＝…＝un+k+1The remaining interior node vectors may be determined using the cumulative chord length method, where the formula is:
wherein n is m + k-1, which represents the number of control vertices of the NURBS curve, and k represents NURBSThe number of curves (which may be, for example, 3), | Δ qi-1|＝|qi-qi-1|，
And ui+k+1And (7) corresponding.
Then, solving the coordinate data of the control vertex according to the following formula;
wherein p (u) represents the symbol of the above formula, djCoordinate data representing the jth control vertex, Ni,k(u) represents a k-th order B-spline basis function, defined by the DeBoolean-Corx recursion equation, as follows:
when the NURBS curve is positively solved, firstly, the coordinate data of the tool location points in the tool path file can be extracted, and then the node vectors corresponding to the tool location points on the NURBS curve are solved according to the following formula;
where n denotes the number of control vertices of the NURBS curve, k denotes the number of times of the NURBS curve, ljIndicating the distance from the jth control vertex to the jth-1 control vertex.
Finally, the node vector U ═ U corresponding to the known knife location point0,u1,···,ui+k+1]Control vertex diOn the premise of (i ═ 0,1, ·, n) and the times k, solving the coordinate data of the points corresponding to the tool bit points on the NURBS curve according to the following formula;
it should be noted that, in the inverse deformation method, as shown in fig. 4, if the ideal curved surface is a horizontal curved surface and the deformed curved surface is an upward convex surface, the compensation curved surface is a downward convex surface.
In the embodiment of the present invention, for the geometric data of the processing surface measured by the non-contact on-machine measurement method, the geometric data is coordinate data of the processing surface (i.e. measured point cloud thereon), and according to the corresponding geometric registration data, the process of compensating and correcting the numerical control processing program of the workpiece may be:
firstly, carrying out NURBS curved surface reconstruction on a machined profile by using an inverse deformation method according to geometric registration data, and calculating a tool path by using the reconstructed NURBS curved surface;
and then, according to the calculated tool path, correcting the corresponding tool path file to generate an NC code with compensation.
When the NURBS curved surface is reconstructed on the processing molded surface by utilizing an inverse deformation method according to the geometric registration data, firstly, (m +1) x (n +1) control vertexes d in the reconstructed NURBS curved surface can be given according to the geometric registration data of the actually measured point cloud and based on the characteristic extraction of the processing regioni,j(i 0,1, m, j 0,1, n) and then given the order k and l of the node vectors U and V in the two parameter directions determined on the basis of the surface shape point, where U is [ U ], [ n ]0,u1,···,ui+k+1]，V＝[v0,v1,···,vi+l+1]And the reconstructed NURBS surface is defined as:
given any set of parameter values (u, v) within the surface definition domain, the process of finding the corresponding point coordinate data p (u, v) on the NURBS surface may be:
firstly, executing a Boolean recursion algorithm on m +1 control vertexes along the direction of the v parameter by using the v parameter value,
coordinate data of control vertexes, which are used as intermediate vertexes and can form an intermediate polygon along the u parameter direction;
and then, executing a Boolean recursion algorithm on the intermediate polygon by using the u parameter value pair, and obtaining a point which is the point coordinate data p (u, v) corresponding to the parameter value (u, v) on the NURBS curved surface.
It should be noted that, the specific process of the NURBS surface reconstruction may refer to the above-mentioned process of inverse summation and forward calculation of the NURBS curve, so as to modify the coordinate data of the tool location point in the tool path file based on the coordinate data of the point corresponding to the tool location point on the NURBS surface, and generate the NC code with compensation.
The above embodiments describe the workpiece processing method based on-machine measurement according to the present invention, and the workpiece processing system based on-machine measurement according to the present invention will be described with reference to the embodiments and the accompanying drawings.
Referring to fig. 5, an embodiment of the present invention further provides an on-machine measurement based workpiece processing system, including:
a data measuring module 51 for measuring geometrical data of the machined surface of the workpiece by means of on-machine measurement;
a registration adjustment module 52, configured to perform registration adjustment on the geometric data according to the geometric data and a preset ideal workpiece model, so as to obtain geometric registration data of the machining surface;
a compensation correction module 53, configured to perform compensation correction on the numerical control machining program of the workpiece according to the geometric registration data;
and the numerical control processing module 54 is used for processing the workpiece by using the compensated and corrected numerical control processing program.
According to the workpiece processing system provided by the embodiment of the invention, the geometric data of the processing surface of the workpiece is measured in an on-machine measurement mode, the geometric data of the processing surface is used for compensating and correcting the numerical control processing program, and the workpiece is processed by the numerical control processing program after compensation and correction, so that the workpiece can be subjected to self-adaptive processing based on the geometric size data of the workpiece measured on-machine, and the qualified rate and the processing efficiency of the processed workpiece are improved.
It should be noted that the data measurement module 51, the registration adjustment module 52, the compensation correction module 53, and the compensation correction module 54 according to the embodiment of the present invention may form a closed-loop workpiece geometry adaptive processing system. Referring to fig. 6, the data measuring module may measure the geometric data of the machined surface by using a machine tool measuring head through contact on-machine measurement and/or by using a three-dimensional laser scanner through non-contact on-machine measurement; the registration adjustment module can perform reference registration analysis and registration analysis under multiple constraints on the basis of contact-type on-machine measurement by utilizing a data set of actually-measured characteristic points and a preset ideal workpiece model to solve machining errors and adjust the measured geometric data, and/or perform reference registration analysis and registration analysis under multiple constraints on the basis of non-contact-type on-machine measurement by utilizing actually-measured point cloud data and the preset ideal workpiece model to solve the machining errors and adjust the measured geometric data; the compensation correction module can calculate the number and coordinate data of the tool positions by using an ideal tool path file, carries out NURBS curve reconstruction according to geometric registration data, modifies the coordinate data of the tool positions in the tool path file until all the tool positions are compensated, obtains compensated NC codes after post-processing, and/or carries out pretreatment on the geometric registration data of the actually measured point cloud, extracts characteristic point data of a processing area, redesigns a processing profile based on point cloud reconstruction, calculates the tool position track by using the reconstructed NURBS curve, and generates compensated NC codes; the compensation correction module can input the original NC code or the NC code with compensation into a numerical control machine tool to carry out numerical control machining on the workpiece.
Optionally, the data measurement module is specifically configured to:
and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode.
Optionally, the registration adjustment module includes:
the extraction unit is used for dispersing the preset ideal workpiece model into point cloud data based on the STL format and extracting coordinate data of a triangular control vertex in a corresponding STL file;
the first calculation unit is used for calculating covariance matrixes of the extracted control vertexes and the actually measured point clouds corresponding to the geometric data respectively according to the following formulas based on a principal component analysis method;
the first registration unit is used for solving the covariance matrix and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
a second calculation unit for calculating rigid body transformations R and T that minimize the f-value, based on an iterative closest point algorithm, of the following constraint conditions;
a second registration unit, configured to perform registration adjustment on the initial registration data by using the R and the T to obtain the geometric registration data;
wherein n is the number of the control vertexes or the actually measured point clouds, xiIs the abscissa of the control vertex or the measured point cloud,
is the mean, y, of the abscissas of the control vertices or the measured point cloudiIs the ordinate of the control vertex or the measured point cloud,
is the mean value of the vertical coordinates, p, of the control vertex or the measured point cloudiAs coordinate data of said control vertices, qiAnd initial registration data corresponding to the actually measured point cloud.
Optionally, if the geometric data of the processing surface of the workpiece is measured in a contact-type on-machine measurement manner, the geometric data is coordinate data of a feature point on the processing surface, and the compensation correction module includes:
the third calculation unit is used for carrying out inverse calculation on the NURBS curve by utilizing a NURBS reconstruction theory according to the geometric registration data and carrying out forward calculation on the NURBS curve to obtain coordinate data of points corresponding to the tool location points on the NURBS curve;
and the first correcting unit is used for correcting the coordinate data of the tool location point in the tool path file by using an inverse deformation method according to the coordinate data of the point corresponding to the tool location point on the NURBS curve and the coordinate data of the tool location point in the tool path file, and generating an NC code with compensation.
Optionally, if the geometric data of the processing surface of the workpiece is measured by using a non-contact on-machine measurement method, the compensation correction module includes:
the fourth calculation unit is used for carrying out NURBS curved surface reconstruction on the machined profile by using an inverse deformation method according to the geometric registration data and calculating a tool path by using the reconstructed NURBS curved surface;
and the second correcting unit is used for correcting the corresponding tool path file according to the calculated tool position track and generating an NC code with compensation.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (8)
1. A workpiece processing method based on-machine measurement, which is characterized by comprising the following steps:
measuring the geometric data of the processing surface of the workpiece by using an on-machine measuring mode;
according to the geometric data and a preset ideal workpiece model, carrying out registration adjustment on the geometric data to obtain geometric registration data of the machining surface;
according to the geometric registration data, compensating and correcting a numerical control machining program of the workpiece;
processing the workpiece by using the compensated and corrected numerical control processing program;
wherein, according to the geometric data and a preset ideal workpiece model, the registration adjustment is performed on the geometric data to obtain geometric registration data of the processing surface, and the method comprises the following steps:
dispersing the preset ideal workpiece model into point cloud data based on an STL format, and extracting coordinate data of a triangular control vertex in a corresponding STL file;
based on a principal component analysis method, respectively calculating covariance matrixes of the extracted control vertexes and actually measured point clouds corresponding to the geometric data according to the following formula;
solving the covariance matrix, and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
based on an iterative closest point algorithm, rigid body transformations R and T which enable the f value to be minimum and are under the following constraint conditions are calculated;
performing registration adjustment on the initial registration data by using the R and the T to obtain the geometric registration data;
wherein n is the number of the control vertexes or the actually measured point clouds, xiIs the abscissa of the control vertex or the measured point cloud,
is the mean, y, of the abscissas of the control vertices or the measured point cloudiIs the ordinate of the control vertex or the measured point cloud,
is the control jackMean value of the ordinate, p, of a point or of the measured point cloudiAs coordinate data of said control vertices, qiAnd initial registration data corresponding to the actually measured point cloud.
2. The method of claim 1, wherein said measuring the geometric data of the work surface of the workpiece by on-machine measurement comprises:
and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode.
3. The workpiece processing method of claim 2, wherein if the geometric data of the processing surface of the workpiece is measured by contact-type on-machine measurement, the geometric data is coordinate data of a feature point on the processing surface, and the compensation modification of the numerical control processing program of the workpiece according to the geometric registration data comprises:
according to the geometric registration data, carrying out inverse calculation on a NURBS curve by using a NURBS reconstruction theory, and carrying out forward calculation on the NURBS curve to obtain coordinate data of points on the NURBS curve corresponding to the cutter location point;
and correcting the coordinate data of the tool location point in the tool path file by using an inverse deformation method according to the coordinate data of the point corresponding to the tool location point on the NURBS curve and the coordinate data of the tool location point in the tool path file, and generating an NC code with compensation.
4. The workpiece processing method of claim 2, wherein if the geometric data of the processing surface of the workpiece is measured by non-contact on-machine measurement, the performing compensation modification on the numerical control processing program of the workpiece according to the geometric registration data comprises:
according to the geometric registration data, carrying out NURBS curved surface reconstruction on the machined profile by using an inverse deformation method, and calculating a tool path by using the reconstructed NURBS curved surface;
and correcting the corresponding tool path file according to the calculated tool position track to generate an NC code with compensation.
5. An on-machine measurement based workpiece processing system, comprising:
the data measurement module is used for measuring the geometric data of the processing surface of the workpiece in an on-machine measurement mode;
the registration adjustment module is used for carrying out registration adjustment on the geometric data according to the geometric data and a preset ideal workpiece model to obtain geometric registration data of the machining surface;
the compensation correction module is used for compensating and correcting the numerical control machining program of the workpiece according to the geometric registration data;
the numerical control processing module is used for processing the workpiece by using the compensated and corrected numerical control processing program;
wherein the registration adjustment module comprises:
the extraction unit is used for dispersing the preset ideal workpiece model into point cloud data based on the STL format and extracting coordinate data of a triangular control vertex in a corresponding STL file;
the first calculation unit is used for calculating covariance matrixes of the extracted control vertexes and the actually measured point clouds corresponding to the geometric data respectively according to the following formulas based on a principal component analysis method;
the first registration unit is used for solving the covariance matrix and carrying out initial registration adjustment on the geometric data according to a solving result to obtain initial registration data;
a second calculation unit for calculating rigid body transformations R and T that minimize the f-value, based on an iterative closest point algorithm, of the following constraint conditions;
a second registration unit, configured to perform registration adjustment on the initial registration data by using the R and the T to obtain the geometric registration data;
wherein n is the number of the control vertexes or the actually measured point clouds, xiIs the abscissa of the control vertex or the measured point cloud,
is the mean, y, of the abscissas of the control vertices or the measured point cloudiIs the ordinate of the control vertex or the measured point cloud,
is the mean value of the vertical coordinates, p, of the control vertex or the measured point cloudiAs coordinate data of said control vertices, qiAnd initial registration data corresponding to the actually measured point cloud.
6. The workpiece processing system of claim 5, wherein the data measurement module is specifically configured to:
and measuring the geometric data of the processing surface of the workpiece by using a contact on-machine measuring mode and/or a non-contact on-machine measuring mode.
7. The workpiece processing system of claim 5, wherein if the geometric data of the processing surface of the workpiece is measured by contact-type on-machine measurement, the geometric data is coordinate data of a feature point on the processing surface, and the compensation modification module comprises:
the third calculation unit is used for carrying out inverse calculation on the NURBS curve by utilizing a NURBS reconstruction theory according to the geometric registration data and carrying out forward calculation on the NURBS curve to obtain coordinate data of points corresponding to the tool location points on the NURBS curve;
and the first correcting unit is used for correcting the coordinate data of the tool location point in the tool path file by using an inverse deformation method according to the coordinate data of the point corresponding to the tool location point on the NURBS curve and the coordinate data of the tool location point in the tool path file, and generating an NC code with compensation.
8. The workpiece processing system of claim 5, wherein the compensation correction module comprises, if the geometric data of the processing surface of the workpiece is measured by non-contact on-machine measurement, the compensation correction module:
the fourth calculation unit is used for carrying out NURBS curved surface reconstruction on the machined profile by using an inverse deformation method according to the geometric registration data and calculating a tool path by using the reconstructed NURBS curved surface;
and the second correcting unit is used for correcting the corresponding tool path file according to the calculated tool position track and generating an NC code with compensation.
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