Error evaluation method and correction method based on flexible clamp rack digitization shaping

Abstract

The application discloses a kind of based on flexible clamp rack digital shaping error evaluation method and correction method, including the following steps: the final support position of support column numerical model capable of supporting skin numerical model is generated, and the surface equation of current skin numerical model is obtained;According to the final support position coordinate data of support column numerical model, the support column on rack is controlled to move to corresponding position;The motion position of each support column on rack and the position coordinate of the end of each current support column are obtained, the support surface equation of support column is fitted, the straight line equation of straight line through the end position coordinate point of each support column and perpendicular to the plane where rack is located;The skin degree of the surface equation between skin numerical model and support surface is calculated, and the error of rack shaping is evaluated according to skin degree. The shape error of support surface of rack is evaluated by using the skin degree of shape formed by the end of support column of rack and actual numerical model surface shape, so that the quality of rack shaping is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of digital measurement, and particularly relates to an error evaluation method and a correction method based on digital shaping of a flexible clamp rack. BACKGROUND

[0002] In skin milling laser engraving processing, a flexible clamp rack is used to support the skin, and then the skin milling laser engraving processing is performed. The skin is virtually supported by the flexible clamp rack in the special pre-processing software, and the skin is processed by using a virtual processing device, and then corresponding support point data and skin processing NC code are generated. The support point data is analyzed by using a motion control software to generate a motion instruction for rack shaping, and is sent to a lower computer to drive the rack motion. After the motion is completed, the skin part is directly placed on the rack and is adsorbed and positioned, and finally the NC program is imported for processing.

[0003] In this process, since the position accuracy of the support column of the flexible clamp rack is not checked, it is assumed that the shape formed by the support rack after shaping is consistent with the shape of the skin. In the process of installing the adsorbed skin on the flexible clamp rack, the skin may have been deformed, which easily leads to unqualified quality of the skin part processed by the skin milling laser engraving equipment. SUMMARY

[0004] The purpose of the present application is to provide an error evaluation method and a correction method based on digital shaping of a flexible clamp rack, so as to solve the problem that the quality of rack shaping cannot be guaranteed in the skin processing of the flexible clamp rack.

[0005] The present application is realized by the following technical scheme:

[0006] The error evaluation method based on digital shaping of a flexible clamp rack comprises the following steps:

[0007] Place the skin model in the modeling software on the rack model, adjust the position of the support column model on the rack, make the support column model fit the skin model, generate the final support position of the support column model capable of supporting the skin model, and obtain the surface equation of the current skin model;

[0008] According to the final support position coordinate data of the support column model, control the support column on the rack to move to the corresponding position;

[0009] Obtain the motion position of each support column on the rack and the position coordinate of the end of each support column;

[0010] According to the position coordinate of the end of each support column, the support surface equation of the support column is fitted and generated;

[0011] A straight line equation of a straight line is fitted according to position coordinates of ends of each support column, and the straight line is a line passing through the end position coordinate points of each support column and being perpendicular to a plane where the bent frame is located;

[0012] Intersections of each straight line and the skin numerical model surface and the support surface are obtained, and a skin fitting degree between the skin numerical model surface and the support surface is calculated according to the obtained intersection coordinate data, and a bent frame shaping error is evaluated according to the skin fitting degree.

[0013] In some embodiments, a field coordinate system is established in the modeling software, a relative relationship between the bent frame, the machine tool and the field coordinate system is mapped to the modeling software, and a position of the bent frame numerical model is adjusted in the modeling software according to the relative positions of the bent frame, the machine tool and the field coordinate system, so that the position of the bent frame numerical model is consistent with the field.

[0014] In some embodiments, residual sum of squares of the end position coordinates of each support column is calculated, and a surface equation coefficient of the support surface equation is obtained under the condition that the residual sum of squares is minimum.

[0015] In some embodiments, the skin fitting degree between the skin numerical model surface and the support surface is calculated according to the intersection coordinates of each straight line and the skin numerical model surface and the support surface, and the skin fitting degree corresponding to each support column is calculated.

[0016] In some embodiments, the shaping error is evaluated according to the skin fitting degree corresponding to each support column.

[0017] In some embodiments, the skin fitting degree corresponding to each support column is compared with a set skin fitting degree threshold value, and when the skin fitting degree corresponding to each support column is greater than the set skin fitting degree threshold value, it is judged that the bent frame shaping error meets the requirements of skin processing.

[0018] In some embodiments, when the skin fitting degree corresponding to each support column is less than the set skin fitting degree threshold value, the shaping of the bent frame and the step of obtaining the skin fitting degree between the skin numerical model surface and the support surface are repeated until the bent frame is shaped to meet the requirements of skin processing.

[0019] On the other hand, the present application also provides a correction method using the error evaluation method of the bent frame digital shaping based on the flexible clamp, and the bent frame shaping is corrected according to the error evaluation result of the bent frame shaping.

[0020] In some embodiments, when the skin fitting degree between the skin numerical model surface and the support surface does not meet the requirements, the shaping of the bent frame and the step of obtaining the skin fitting degree between the skin numerical model surface and the support surface are repeated until the bent frame shaping error meets the requirements of skin processing.

[0021] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0022] The present application adopts the shape formed at the end of the support column of the rack to evaluate the shape error of the support surface of the rack, and ensures the quality of the shape adjustment of the rack, and provides a basis for improving the machining precision of the skin milling laser engraving.

[0023] The present application improves the matching degree of the rack and the skin, improves the installation position precision of the skin on the rack, and only needs to scan by using a laser tracker to detect the point data, improves the efficiency of the shape adjustment and measurement. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0025] Figure 1 The present application is an embodiment of the present application, which places the skin numerical model on the rack numerical model to adjust the shape of the rack numerical model.

[0026] Figure 2 The present application is an embodiment of the present application, which places the skin numerical model on the rack numerical model to adjust the shape of the rack numerical model.

[0027] Figure 3 The present application is an embodiment of the present application, which places the skin numerical model on the rack numerical model to adjust the shape of the rack numerical model.

[0028] Among them:

[0029] 10, skin numerical model;

[0030] 20, rack, 21, support column;

[0031] 30, fitted straight line;

[0032] 40, fitted support surface. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in combination with the drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only parts related to the present application are shown in the drawings, but not all. Before discussing the example embodiments in more detail, it should be mentioned that some example embodiments are described as processes or methods depicted as flowcharts. Although the flowchart describes each operation (or step) as a sequential process, many of the operations can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operations are completed, but can also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, etc.

[0034] The present application avoids the problem that the support shape of the digitalized and shaped support frame cannot match the actual skin support requirements by evaluating the error between the actual position shape of the shaped support column of the flexible clamp support frame in the chemical milling laser engraving equipment and the virtual position of the support skin in the simulation digital model. Based on the evaluation result of the shaping error, the flexible clamp support frame support shape can be corrected.

[0035] Reference Figure 1 The flexible clamp support frame 20 includes a plurality of support columns 21 arranged in the vertical direction. By adjusting the position of the end of the support column, the position of the end of the support column can form any profile matching the shape of the skin to be processed, thereby supporting the skin.

[0036] The support columns on the flexible clamp support frame are arranged in an array, generally not less than 3x3, and the number of support columns is not less than 9.

[0037] In some embodiments of the present application, the error evaluation method based on the digital shaping of the flexible clamp support frame includes the following steps:

[0038] Place the skin digital model on the support frame digital model in the modeling software, adjust the position of the support column digital model on the support frame, make the support column digital model fit the skin digital model, generate the final support position of the support column digital model that can support the skin digital model, and obtain the surface equation of the current skin digital model;

[0039] According to the final support position coordinate data of the support column digital model, control the movement of the support column on the support frame to the corresponding position;

[0040] Obtain the movement position of each support column on the support frame and the position coordinates of the end of each support column;

[0041] Fitting a support surface equation of the support column according to the position coordinates of the end of each support column;

[0042] Fitting a straight line equation of a straight line according to the position coordinates of the end of each support column, the straight line being a line passing through the position coordinate points of the end of each support column and being perpendicular to the plane where the bent frame is located;

[0043] Obtaining the intersection points of each straight line and the skin numerical model surface and the support surface, and calculating the skin degree of the skin numerical model surface and the support surface according to the obtained intersection coordinate data, and evaluating the error of the bent frame shaping according to the skin degree.

[0044] In some embodiments, a field coordinate system is established in the modeling software, the relative relationship between the bent frame, the machine tool and the field coordinate system is mapped into the modeling software, and the position of the bent frame numerical model is adjusted in the modeling software according to the relative positions of the bent frame, the machine tool and the field coordinate system, so that the position of the bent frame numerical model is consistent with the field.

[0045] In some embodiments, the residual sum of squares of the end position coordinates of each support column is calculated, and the surface equation coefficients of the support surface equation are obtained under the condition that the residual sum of squares is minimum.

[0046] In some embodiments, the skin degree between the skin numerical model surface and the support surface is calculated according to the intersection coordinate of each straight line and the skin numerical model surface and the support surface.

[0047] In some embodiments, the shaping error is evaluated according to the skin degree corresponding to each support column.

[0048] In some embodiments, the skin degree corresponding to each support column is compared with the set skin degree threshold value, and when the skin degree corresponding to each support column is greater than the set skin degree threshold value, it is judged that the bent frame shaping error meets the requirements of skin processing.

[0049] In some embodiments, when the skin degree corresponding to the support column is less than the set skin degree threshold value, the shaping of the bent frame and the step of obtaining the skin degree between the skin numerical model surface and the support surface are repeated until the bent frame is shaped to meet the requirements of skin processing.

[0050] The error evaluation method and the correction method of the flexible clamp bent frame digital shaping of the present application will be described in detail below in combination with specific embodiments.

[0051] S01, place the skin numerical model 10 to be processed into the modeling software, and import the bent frame numerical model of the milling laser marking device into the modeling software.

[0052] S02, as Figure 1In the modeling software, the field coordinates are established, the relationship of the bent frame, the machine tool and the field coordinate system is determined, the relative relationship among the three is mapped to the modeling software, and the position of the bent frame model is adjusted in the modeling software according to the relative positions of the bent frame, the machine tool and the field coordinate system, so that the position of the bent frame model is consistent with the actual position in the field.

[0053] S03, the skin model is placed on the bent frame model, and the skin model is placed as much as possible in the middle of the bent frame;

[0054] Through the modeling software and the processing auxiliary plug-in, the skin model and the support column model of the bent frame are manually adjusted so that the support column model is attached to the skin model, then the final support position of the support column model capable of supporting the skin model is generated, and the surface equation of the current skin model is obtained.

[0055] The expression of the surface equation of the skin model under the support of the current support column can be expressed as:

[0056] ;

[0057] Where (x, y, z) is the point data on the surface of the skin model, is the known surface equation coefficient.

[0058] S04, according to the final support position coordinate data of the support column in step S03, the motion control software is used to analyze the motion instructions of the bent frame and send them to the lower computer to drive the support column on the bent frame to move to the specified position.

[0059] S05, the motion position of the current n support columns is obtained through the motion control software, where the motion position of the support column refers to the position of the support column after being driven to move according to the target instructions, and the position coordinates of the ends of all support columns are:

[0060] The first support column end position coordinate is: ;

[0061] The second support column end position coordinate is: ;

[0062] The third support column end position coordinate is: ;

[0063] The fourth support column end position coordinate is: ;

[0064] …

[0065] The n-th support column end position coordinate is: .

[0066] The end position data of the support column on the rack is acquired by means of laser tracker measuring points, which is simple in measurement and accurate and reliable in measurement data.

[0067] S06, using the position coordinates of the ends of the n support columns in step S05, a spatial quadratic surface fitting is performed on the surface formed by the support columns of the rack by means of surface fitting, to obtain the surface of the support columns on the rack.

[0068] The spatial quadratic surface model formed by the position coordinates of the ends of the n support columns can be expressed as:

[0069] ;

[0070] Wherein, is the coefficient of the surface equation to be solved.

[0071] In order to fit the spatial quadratic surface of the position coordinates of the ends of the n support columns by means of least square method, the residual sum of squares of the position coordinates of the ends of the n support columns is calculated according to the position coordinates of the ends of the n support columns. , which can be expressed as:

[0072] ;

[0073] In order to find the best fitting spatial quadratic surface, it is necessary to minimize According to the expression of the residual sum of squares , the partial derivative of each coefficient of the surface equation to be solved is calculated, and the partial derivative is equal to zero, which is expressed as:

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] ;

[0079] .

[0080] The coefficients of the spatial quadratic surface equation formed by the position coordinates of the ends of the n support columns can be solved by the above equation, which are respectively: , , , , , .

[0081] The surface equation of the fitting support surface 40 fitted by the end position coordinates of the support columns is:

[0082] .

[0083] S07, according to the end position coordinates of the n support columns and the field coordinate system, fitting the straight line equation of the straight line passing through the end position coordinates of each support column and perpendicular to the X-Y plane of the field coordinate system, the straight line is the fitted straight line 30, refer to Figure 2 respectively as follows:

[0084] The straight line equation passing through the coordinates is expressed as:

[0085] ;

[0086] The straight line equation passing through the coordinates is expressed as:

[0087] ;

[0088] The straight line equation passing through the coordinates is expressed as:

[0089] ;

[0090] …

[0091] The straight line equation passing through the coordinates is expressed as:

[0092] .

[0093] S08, combining the straight line equation of step S07, solving the intersection point of the n straight lines and the skin NURBS surface equation generated in the model, the intersection point coordinates of each straight line and the skin NURBS surface equation are:

[0094] The intersection point of straight line and skin NURBS surface equation is: ;

[0095] The intersection point of straight line and skin NURBS surface equation is: ;

[0096] The intersection point of straight line and skin NURBS surface equation is: ;

[0097] …

[0098] The intersection point of straight line The intersection of the skin numerical model surface equation and the straight line equation is: .

[0099] S09, combined with the straight line equation of step S07, the intersection of n straight lines and the curved surface equation fitted by the support column of the shelf is solved, as shown in Figure 3 , the intersection coordinates of each straight line and the curved surface fitted by the support column of the shelf are respectively:

[0100] Straight line and the intersection of the curved surface fitted by the support column is: ;

[0101] Straight line and the intersection of the curved surface fitted by the support column is: ;

[0102] Straight line and the intersection of the curved surface fitted by the support column is: ;

[0103] …

[0104] Straight line and the intersection of the curved surface fitted by the support column is: .

[0105] S10, according to the intersection coordinate data in step S08 and step S09, the skin numerical model surface and the support surface fitted by the end of the shelf support column The skin degree of each support column is calculated and represented as:

[0106] ;

[0107] ;

[0108] ;

[0109] …

[0110] .

[0111] S11, using the skin degree calculated in step S10, judge whether the skin degree corresponding to each support column is greater than the corresponding set skin degree threshold , represented as:

[0112] ;

[0113] ;

[0114] ;

[0115] …

[0116] .

[0117] If the above conditions are met, the judgment of the adjustment error is completed, and the shape of the support column is adjusted to meet the requirements of the skin processing.

[0118] S12, if the conditions of step S11 cannot be met, the position deviation can be adjusted appropriately, otherwise the position accuracy of the support column needs to be further detected and the position of the support column is adjusted according to the position accuracy;

[0119] Repeat steps S04-S11 to judge the degree of surface fitting, until the conditions of step S11 are met, and the digital adjustment of the flexible clamp rack is completed.

[0120] In the case that the position accuracy of the support column of the rack cannot meet the accuracy requirements, the adjustment of the rack is corrected according to the judgment result of the adjustment error, and the support column of the rack is adjusted.

[0121] On the other hand, the present application also provides a method for correcting the error of the rack adjustment based on the error evaluation method of the digital adjustment of the flexible clamp rack, and the adjustment of the rack is corrected according to the error evaluation result of the rack adjustment.

[0122] In some embodiments, when the degree of surface fitting between the skin numerical model surface and the support surface does not meet the requirements, the adjustment of the rack and the step of obtaining the degree of surface fitting between the skin numerical model surface and the support surface are repeated until the adjustment error of the rack meets the requirements of the skin processing.

[0123] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change based on the technical essence of the present application to the above embodiment falls within the scope of protection of the present application.

Claims

1. The error evaluation method based on the digital adjustment of the flexible fixture is characterized by: The following steps are involved: In the modeling software, the skin digital model is placed on the rack digital model, and the position of the supporting column digital model on the rack is adjusted to make the supporting column digital model fit the skin digital model. The final support position of the supporting column digital model that can support the skin digital model is generated, and the surface equation of the current skin digital model is obtained. According to the final support position coordinate data of the support column digital model, the support columns on the rack are controlled to move to the corresponding positions; Obtain the movement position of each support column on the rack and the current position coordinates of the end of each support column; Generate the support surface equation of the support column according to the position coordinates of the end of each support column; The linear equation of a straight line is obtained by fitting the position coordinates of the ends of the supporting columns, wherein the straight line is a line passing through the coordinate points of the end positions of the supporting columns and perpendicular to the plane where the rack is located; Obtain the intersection points of each straight line with the skin digital model surface and the support surface, and calculate the fit between the skin digital model surface and the support surface based on the obtained intersection coordinate data, and evaluate the error of the rack adjustment based on the fit.

2. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 1 is characterized in that: Establish an on-site coordinate system in the modeling software, map the relative relationship between the rack, machine tool and on-site coordinate system into the modeling software, and adjust the position of the rack digital model in the modeling software according to the relative positions of the rack, machine tool and on-site coordinate system to make the position of the rack digital model consistent with the site.

3. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 1 is characterized in that: The residual sum of squares of the end position coordinates of each supporting column is calculated, and the surface equation coefficient of the supporting surface equation is obtained under the condition of minimizing the residual sum of squares.

4. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 1 is characterized in that: The degree of fit between the skin digital model surface and the support surface is calculated by respectively calculating the degree of fit corresponding to each support column according to the coordinates of the intersection points of each straight line with the skin digital model surface and the support surface.

5. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 4 is characterized in that: The adjustment error is evaluated based on the corresponding mold fit of each support column.

6. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 5 is characterized in that: The degree of fit corresponding to each support column is compared with the set degree of fit threshold. When the degree of fit corresponding to each support column is greater than the set degree of fit threshold, it is determined that the rack adjustment error meets the requirements of skin processing.

7. The error evaluation method based on digital shape adjustment of flexible fixture rack according to claim 6 is characterized in that: When the degree of fit corresponding to the support column is less than the set fit threshold, repeat the steps of adjusting the shape of the rack and obtaining the fit between the skin digital model surface and the support surface until the rack is adjusted to meet the requirements of skin processing.

8. A correction method for the error evaluation method based on digital shape adjustment of flexible fixtures according to any one of claims 1 to 7, characterized in that: The rack adjustment is corrected according to the error evaluation results of the rack adjustment.

9. The correction method according to claim 8, characterized in that: When the fit between the digital model surface of the skin and the support surface does not meet the requirements, the steps of adjusting the shape of the frame and obtaining the fit between the digital model surface of the skin and the support surface are repeated until the shape adjustment error of the frame meets the requirements of skin processing.

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