A method and system for in-situ measurement of a vane multi-wire laser standard part

Abstract

The application discloses a kind of blade multi-line laser standard piece in-situ measurement method and system, method includes: constructing blade theoretical model, according to blade theoretical model and line laser measurement characteristic, blade is divided into measurement area, according to the measurement area of division blade line laser measurement method is determined;According to the specification of blade to be measured, blade theoretical model and line laser measurement method, standard piece is made;Standard piece is measured respectively using three coordinate measuring instrument and line laser measurement method, and the conversion relationship of line laser coordinate system and blade coordinate system is determined;According to line laser measurement method, the complete point cloud of blade section surface to be measured is obtained by measuring the blade to be measured;According to the conversion relationship, the complete point cloud of blade section surface to be measured is converted to blade coordinate system, and the machining allowance is determined according to blade theoretical model and the point cloud converted to blade coordinate system.The application can realize fast, efficient and accurate in-situ measurement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical measurement, and more particularly relates to a kind of vane multi-line laser standard part in-situ measurement method and system. BACKGROUND

[0002] Part of the vane (such as the vane of aerospace engine) has high precision requirement, which puts forward high requirement for measurement. The currently commonly used measurement method is to measure multiple key surfaces of the vane by a coordinate measuring machine in a contact manner. The main defects of the method are as follows: the working environment requirement is high, the anti-vibration performance of the equipment itself is poor; the measurement cost is high, the process is very complex, and the speed is slow; the fillet of the vane edge is small, and it is difficult to measure the points.

[0003] Optical measurement technology has the advantages of non-contact, high measurement efficiency, strong data real-time performance, and low cost. For some workpieces with complex surface topography and small edge fillet, it is difficult to measure by contact method, and optical non-contact measurement can overcome the difficulty of point taking at the edge in contact measurement method, greatly improving the density and accuracy of detection.

[0004] There are two major difficulties in current optical detection. The first difficulty is high-precision splicing of measurement data of multiple optical measurement heads. Because the measurement accuracy of an optical measurement head is often related to the measurement range, the larger the measurement range, the lower the measurement accuracy. Therefore, in order to ensure the measurement accuracy or cope with some small fillet detection areas, multiple optical measurement heads are often used to splice the data measured by two or more optical measurement heads with high precision, which is of great significance to optical measurement. The second difficulty is to compare the measured point cloud data with the theoretical model to obtain the processing allowance data, i.e. in-situ measurement. The commonly used method is point cloud matching algorithm. For complex curved surface workpieces, the matching accuracy cannot meet the actual demand, which becomes a major difficulty in high-precision optical detection.

[0005] Patent document CN107870324B discloses a calibration device and method for a multi-line laser radar. The invention is a convenient and efficient calibration device and method for a rotary 64-line laser radar, which can accurately calibrate the three-dimensional coordinates of the scanning points at the same time. It solves the problems of existing laser radars, such as difficulty in determining the actual position coordinates of laser scanning points, complex shape of scanning trajectory, and complicated calibration process. However, the patent method mainly addresses the first difficulty, i.e. calibrating multiple optical measurement heads by traditional calibration method, and does not solve the problem of calibrating the measurement head and calculating the allowance. Moreover, it is aimed at large-range laser emitters, and the calibration accuracy cannot reach micrometer level. It is not suitable for precision measurement of small and medium-sized workpieces, especially for processing allowance acquisition. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the present application provides a kind of vane multi-line laser standard part in situ measurement method and system, by introducing the standard part structure with the same petiole as the vane to be measured, positioning is carried out through the calibration ball of standard part, the splicing of point cloud data collected by line laser emitter in the vane theoretical model coordinate system is realized, and in-situ measurement can be realized.

[0007] To achieve the above object, according to one aspect of the present application, a kind of multi-line laser standard part in situ measurement method, comprising:

[0008] Constructing vane theoretical model, dividing measurement area according to vane theoretical model and line laser measurement characteristics, determining line laser measurement method of vane according to the measurement area divided;

[0009] According to the specification of the vane to be measured, vane theoretical model and line laser measurement method, make standard part;

[0010] Use three coordinate measuring instrument and line laser measurement method to measure standard part respectively, determine the conversion relationship of line laser coordinate system and vane coordinate system;

[0011] According to line laser measurement method, measure the vane to be measured, and obtain the complete point cloud of the cross-sectional surface of the vane to be measured;

[0012] According to the conversion relationship, the complete point cloud of the cross-sectional surface of the vane to be measured is converted to the vane coordinate system, and the machining allowance is determined according to the vane theoretical model and the point cloud converted to the vane coordinate system.

[0013] Further, the vane is divided into measurement area according to vane theoretical model and line laser measurement characteristics, comprising:

[0014] According to the shape characteristics of line laser measurement range, measurement curvature and vane theoretical model cross-sectional surface, the vane measurement area is divided, and the measurement area includes: vane basin, vane back, left vane edge and right vane edge.

[0015] Further, the line laser measurement method of vane is determined according to the measurement area divided, comprising:

[0016] Two line laser emitters are used to form a measurement group, and the left vane edge of the vane is measured, and a single line laser emitter is used to measure the vane basin;

[0017] Taking z axis as the center, the vane rotates 180 degrees as a whole;

[0018] Two line laser emitters are used to form a measurement group, and the right vane edge of the vane is measured, and a single line laser emitter is used to measure the vane back;

[0019] The measured data is spliced to obtain the complete cross-sectional profile data of a point on the z-axis, the blade is moved along the Z direction, and the above steps are repeated to obtain the overall profile data of the blade airfoil.

[0020] Further, the standard part is manufactured according to the specification of the blade to be measured, a theoretical model of the blade, and the line laser measurement method, and includes:

[0021] The specification parameters of the standard part shank are obtained according to the specification parameters of the shank of the blade to be measured;

[0022] The installation positions of the standard part shank calibration ball groups are determined according to the measurement ranges of the line laser emitters of the line laser groups corresponding to the shank and the back of the blade;

[0023] The installation positions of the standard part shank calibration ball groups are determined according to the measurement ranges of the line laser emitters of the line laser groups corresponding to the shank and the back of the blade;

[0024] Further, the standard part is measured by the three-coordinate measuring instrument and the line laser measurement method to determine the conversion relationship between the line laser coordinate system and the blade coordinate system, and includes:

[0025] The first point set is obtained by measuring the standard part according to the line laser measurement process;

[0026] The second point set is obtained by measuring the standard part using the three-coordinate measuring instrument;

[0027] The conversion relationship between the line laser coordinate system and the blade coordinate system is determined according to the two-dimensional point set and the three-dimensional point set.

[0028] Further, the first point set is obtained by measuring the standard part according to the line laser measurement process, and includes:

[0029] The calibration ball profiles of the shank calibration ball groups and the back calibration ball groups are measured using the line laser emitters to obtain the calibration ball profile coordinates of the shank calibration ball groups and the back calibration ball groups;

[0030] The center of the ball is fitted according to the calibration ball profile coordinates of the shank calibration ball groups and the back calibration ball groups to obtain the center coordinates of the shank calibration ball groups and the back calibration ball groups, and the first point set is obtained by combination.

[0031] Further, the second point set is obtained by measuring the standard part using the three-coordinate measuring instrument, and includes:

[0032] The shank key points are determined by measuring the shank part of the standard part using the three-coordinate measuring instrument;

[0033] The blade coordinate system is established based on the shank key points;

[0034] The three-coordinate measuring instrument is used for respectively measuring the vane back calibration ball group and the vane edge calibration ball group of the standard part, and three-dimensional point sets in the vane coordinate system are obtained.

[0035] Based on the dimension of the first point set and the three-dimensional point set, a second point set is obtained.

[0036] Further, the conversion relationship between the line laser coordinate system and the vane coordinate system is determined according to the first point set and the second point set, including:

[0037] Each point in the first point set and the second point set is subtracted by the center point, and a first center point set and a second center point set are obtained.

[0038] A covariance matrix is determined according to the first center point set and the second center point set, and a rotation matrix and a translation matrix are obtained according to singular value decomposition.

[0039] Further, the machining allowance is determined according to the vane theoretical model and the point cloud converted to the vane coordinate system, including: the machining allowance is determined based on the radius search method according to the vane theoretical model and the point cloud converted to the vane coordinate system in the vane coordinate system.

[0040] According to another aspect of the present application, a vane multi-line laser standard part in-situ measurement system is provided, including:

[0041] The first main module is used for constructing a vane theoretical model, dividing a measurement region of the vane according to the vane theoretical model and a line laser measurement characteristic, and determining a line laser measurement method of the vane according to the divided measurement region.

[0042] The second main module is used for manufacturing a standard part according to the specification of a to-be-measured vane, the vane theoretical model and the line laser measurement method.

[0043] The third main module is used for respectively measuring the standard part by using a three-coordinate measuring instrument and a line laser measurement method, and determining a conversion relationship between a line laser coordinate system and a vane coordinate system.

[0044] The fourth main module is used for measuring the to-be-measured vane according to the line laser measurement method, and obtaining a complete point cloud of a cross-sectional profile of the to-be-measured vane.

[0045] The fifth main module is used for converting the complete point cloud of the cross-sectional profile of the to-be-measured vane to the vane coordinate system according to the conversion relationship, and determining a machining allowance according to the vane theoretical model and the point cloud converted to the vane coordinate system.

[0046] Overall, the above technical solutions conceived by the present application can achieve the following beneficial effects compared with the prior art:

[0047] 1. The in-situ measurement method of the present application realizes the determination of the conversion relationship between the blade coordinate system and the line laser coordinate system based on the blade theoretical model, three-coordinate measurement and line laser measurement method, without repeated calibration, and can convert the measured point cloud of the blade to be measured measured by the line laser measurement to the blade coordinate system, which is used to obtain the machining allowance of the blade theoretical model, and realizes fast, efficient and accurate in-situ measurement.

[0048] 2. The in-situ measurement method of the present application realizes the multi-line laser in-situ measurement of the medium and small blade by using the standard part designed according to the theoretical model of the medium and small blade to be measured, which can solve the problem that the precision of the data collected by multiple line laser devices cannot meet the high-precision measurement requirements, overcome the problem that the commonly used point cloud matching data processing method has poor effect on high complex surface, and meet the measurement requirements of complex parts such as blades.

[0049] 3. The in-situ measurement method of the present application realizes the splicing of the point cloud data collected by the line laser emitter in the blade theoretical model coordinate system by introducing the standard part structure with the same petiole as the blade to be measured and positioning by the calibration ball of the standard part, which takes a big step from measuring the contour to measuring the machining allowance, and can realize in-situ measurement. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a point cloud data schematic diagram of a cross-sectional profile of a medium and small blade to be measured in an embodiment of the present application and its z-axis;

[0051] Figure 2 It is a flowchart of a blade multi-line laser standard part in-situ measurement method in an embodiment of the present application;

[0052] Figure 3 It is a line laser measurement scheme schematic diagram in an embodiment of the present application;

[0053] Figure 4 It is a standard part schematic diagram in an embodiment of the present application;

[0054] Figure 5 It is a schematic diagram of the measurement point cloud of the blade to be measured and the machining allowance of the blade theoretical model in an embodiment of the present application.

[0055] In all the drawings, the same reference signs represent the same technical features, specifically: 1-petiole, 2-blade back, 3-right blade edge, 4-left blade edge, 5-blade basin, 6-line laser emitter, 7-line laser group, 8-standard part petiole, 9-calibration ball mounting seat, 10-blade basin and blade back calibration ball group, 11-blade edge calibration ball group, 12-theoretical cross-sectional profile, 13-measurement point cloud. DETAILED DESCRIPTION

[0056] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0057] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] Those skilled in the art can understand that, unless otherwise stated, the singular forms "a", "an" and "the" used herein also include the plural forms. It should be further understood that the phrase "comprising" used in the specification of the present application means that the features, integers, steps, operations, elements and / or components exist, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0059] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as that generally understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood as having meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as in the embodiments of the present application.

[0060] The in-situ measurement method of the present application is suitable for machining allowance measurement in the field of mechanical machining and polishing process, and is especially suitable for machining allowance measurement of small and medium-sized blades of an aero-engine.

[0061] For the to-be-measured small and medium-sized blade, the main blade size is 50-60mm, and the main load is in the turbine of an aero-engine. The to-be-measured small and medium-sized blade is obtained by processing a blade theoretical model template, and has the same structure as the blade theoretical model. 1 is a blade stem part, which is mainly used for clamping and positioning in the measurement process and is a reference for blade manufacturing. A section at a certain Z coordinate of the blade blade is taken as a measured surface. 2 is a blade back part of the surface, 3 is a right blade edge part of the surface, 4 is a blade basin part of the surface, and 5 is a left blade edge part of the surface. The blade surface is relatively complex, the inlet and outlet edge contour is small, the minimum fillet is less than 0.1mm, the overall blade body is obviously curved, and there is obvious distortion. The blade has high precision requirements, and therefore high requirements are put forward for the measurement.

[0062] The current commonly used measurement method is to measure multiple key surfaces of the blade by a three-coordinate measuring instrument in a contact manner. The main defects are that the working environment requirement is relatively high, the anti-vibration performance of the equipment itself is poor, the measurement cost is high, the process is very complex, and the speed is slow. The fillet of the blade edge part is small, and it is difficult to measure the points.

[0063] The application provides a multi-line laser standard part in-situ measurement method, which comprises steps S100-S500.

[0064] Step S100, a blade theoretical model is constructed, the blade is divided into a measurement region according to the blade theoretical model and a line laser measurement characteristic, and a line laser measurement method of the blade is determined according to the divided measurement region.

[0065] Specifically, the blade is divided into a measurement region according to the blade theoretical model and the line laser measurement characteristic, and the method comprises the following steps.

[0066] The blade measurement region is divided according to a line laser measurement range, a measurement curvature and a shape feature of a cross-sectional surface of the blade theoretical model. The measurement region comprises a blade basin, a blade back, a left blade edge and a right blade edge.

[0067] Because the measurement range of the high-precision line laser transmitter is small, and the measurement effect is not good for relatively sharp edges, the line laser transmitter is suitable for measurement of a relatively flat curved surface. Therefore, the line laser transmitter cannot completely measure the surface of the whole blade in one measurement, and multiple line laser transmitters often need to be combined for joint measurement to completely scan the blade surface. First, the measurement region needs to be divided, and the line laser transmitter is arranged in the measurement region. Figure 1The shape characteristics of the blade section surface at a certain Z coordinate are analyzed. The overall appearance of the blade back part 2 and the blade basin part 4 of the blade section surface is relatively flat, and the curvature is relatively small. The overall appearance of the right blade edge part 3 and the left blade edge part 5 of the blade section surface is relatively sharp, and the corner radius of the blade edge is relatively small. According to the characteristics of the linear laser measurement range and the measurement curvature, and the shape characteristics of the certain section surface of the blade to be measured, the blade is divided into a plurality of measurement regions, the blade basin 2, the blade back 4, the left blade edge 3 and the right blade edge 5.

[0068] In an embodiment of the present application, the linear laser measurement method of the blade is determined according to the divided measurement regions, comprising steps S101-S104:

[0069] Step S101, two linear laser emitters are used to form a measurement group to measure the left blade edge of the blade, and a single linear laser emitter is used to measure the blade basin of the blade;

[0070] Step S102, the blade is rotated by 180 degrees as a whole with the z-axis as the center;

[0071] Step S103, two linear laser emitters are used to form a measurement group to measure the right blade edge of the blade, and a single linear laser emitter is used to measure the blade back of the blade;

[0072] Step S104, the measurement data is spliced to obtain the complete section surface profile data of a point on the z-axis, and the blade is moved along the z-axis direction, and the above steps are repeated to obtain the overall profile data of the blade body;

[0073] It should be noted that in steps S101-S104, the measurement range of any linear laser emitter is greater than the size of any corresponding measurement region.

[0074] Specifically, according to the specific size range of the measurement region, the linear laser is selected to ensure that the measurement range of the selected linear laser is greater than the size of the corresponding measurement region.

[0075] Referring to Figure 3 the linear laser measurement scheme diagram, Figure 3 the linear laser measurement method shown in the figure, one linear laser emitter 6 is used to measure the blade basin part 2 and the blade back part 4, and a linear laser group 7 containing two linear laser emitters is used to measure the left blade edge 3 and the right blade edge 5 of the blade. The two linear laser emitters of the linear laser group 7 are placed orthogonally, and the two linear laser emitters can measure the two sides of the blade edge respectively. All features of the blade to be measured are measured through two processes.

[0076] The linear laser emitter 6 is used to measure the blade basin, and the linear laser group 7 is used to measure the left blade edge of the blade;

[0077] The blade is rotated by 180 degrees as a whole under the condition that the Z coordinate is fixed;

[0078] The blade back is measured by the line laser emitter 6, and the right blade edge is measured by the line laser group 7; the complete cross-sectional profile data of the blade at a certain Z coordinate is obtained through the above process, including the line laser measurement data yb_mea of the blade back line , the line laser measurement data yp_mea of the blade basin line , the line laser measurement data yyl_mea of the left blade edge line , and the line laser measurement data yyr_mea of the right blade edge line The blade is moved along the Z direction, and the complete profile data of the blade body can be measured.

[0079] In another embodiment of the present application, the line laser measurement method of the blade according to the divided measurement regions comprises:

[0080] A plurality of line laser emitters are used to form a measurement group to directly measure each measurement region; or

[0081] A single line laser emitter is selected to sequentially measure each measurement region, and the multiple measurement results are spliced; the measurement range of any line laser emitter is greater than the size of any measurement region corresponding to the line laser emitter.

[0082] It should be noted that the blade theoretical model is a model obtained by a three-dimensional modeling method before the blade is processed and manufactured, which is the final processing condition of the blade in an ideal case. The three-dimensional modeling method includes but is not limited to CAD, which is a common knowledge in the field and will not be described here.

[0083] Step S200, according to the specification of the blade to be measured, the blade theoretical model and the line laser measurement method, a standard part is manufactured;

[0084] Referring to Figure 5 , the structure of the standard part is shown in Figure 5 , which includes a standard part handle 8, a calibration ball mounting seat 9, a blade basin and back calibration ball group 10, and a blade edge calibration ball group 11.

[0085] To manufacture the standard part, the parameters of the standard part need to be determined first. To ensure that the standard part and the blade to be measured are in the same clamping condition, the specification parameters of the standard part handle 8 are consistent with those of the blade handle to be measured; the overall size of the calibration ball mounting part of the standard part is consistent with that of the blade to be measured, and the installation position of each calibration ball is determined as follows:

[0086] According to the measurement range of the linear laser emitter 6 corresponding to the blade basin part 2 and the blade back part 4 of the blade, the installation position of the blade basin and blade back calibration ball group on the standard part is determined, and it is ensured that the installation position of the blade basin and blade back calibration ball group is within the measurement range of the linear laser emitter 6. According to the measurement range of the linear laser emitter of the linear laser group 7 for measuring the left and right blade edges 3 and 5 of the blade, the installation position of the blade edge calibration ball group on the standard part is determined, and it is ensured that the installation range of the blade edge calibration ball group 11 is within the measurement range of the linear laser emitter of the linear laser group 7.

[0087] Finally, the standard part is obtained, which is the same as the petiole parameters of the blade to be measured, so that the standard part and the blade to be measured can be in the same clamping condition; the three calibration balls of the blade basin and blade back calibration ball group 10 can be all scanned by the laser emitted by the linear laser emitter 6 once, and the three calibration balls of the blade edge calibration ball group 11 can be all scanned by the linear laser emitter of the linear laser group 7 once.

[0088] Step S300, respectively using a three-coordinate measuring instrument and a linear laser measurement method to measure the standard part, and determining the conversion relationship between the linear laser coordinate system and the blade coordinate system;

[0089] Specifically, step S300 includes steps S301-S303:

[0090] Step S301, measuring the standard part according to the linear laser measurement process to obtain a first point set;

[0091] The measurement of the standard part according to the linear laser measurement process to obtain the first point set includes:

[0092] The blade basin and blade back calibration ball group and the blade edge calibration ball group of the standard part are measured by the linear laser emitter respectively, and the calibration ball contour coordinates of the blade basin and blade back calibration ball group and the blade edge calibration ball group are obtained.

[0093] According to the calibration ball contour coordinates of the blade basin and blade back calibration ball group and the blade edge calibration ball group, the ball centers are fitted to obtain the ball center coordinates of the blade basin and blade back calibration ball group and the blade edge calibration ball group, and the first point set is obtained by combination.

[0094] Specifically, in the standard part measurement, the standard part is clamped in the same way as the blade to be measured, the line laser emitter 6 is used to measure the blade back pad calibration ball group 10 of the standard part, the XY coordinates of the calibration ball profile of the blade back pad calibration ball group 10 are measured, the ball center is fitted through the measured XY coordinates of the circular profile, and the XY coordinates of the ball center of the blade back pad calibration ball group 10 are obtained; the line laser group 7 is used to measure the blade edge calibration ball group 11 of the standard part, the XY coordinates of the calibration ball profile of the blade edge calibration ball group 11 are measured, the ball center is fitted through the measured XY coordinates of the circular profile, and the XY coordinates of the ball center of the blade edge calibration ball group 11 are obtained. Finally, the XY coordinates of the ball centers of the three calibration balls of the blade back pad calibration ball group 10 in the XY coordinate system of the line laser measurement are obtained, and the three sets of coordinates form a point set A, and the XY coordinates of the ball centers of the three calibration balls of the blade edge calibration ball group 11 in the XY coordinate system of the line laser measurement form a point set B. The point set A and the point set B are the first point set.

[0095] The method for obtaining the center of the circle through the measured circular profile includes:

[0096] According to the circular equation x 2 +y 2 +ax+by+c=0, the equation is obtained

[0097]

[0098] Wherein, a, b, c are unknown numbers to be solved respectively;

[0099] According to the circular profile XY coordinates measured in the line laser coordinate system of the blade back pad calibration ball group 10 and the blade edge calibration ball group 11, the obtained equation can be written in the form of matrix:

[0100]

[0101] Wherein, x1, …, x n are the X-axis coordinates of the circular profile, y1, …, y n are the y-axis coordinates of the circular profile.

[0102] The above equation is in the form of AX=b, and in the equation

[0103]

[0104] The solution is obtained as follows:

[0105]

[0106] After a, b, and c are obtained, the fitting equation of the circular profile is obtained, and then the point sets A and B composed of the XY coordinates of the ball centers of the calibration balls of the blade back pad calibration ball group 10 and the blade edge calibration ball group 11 in the XY coordinate system of the line laser measurement are obtained.

[0107]

[0108] wherein x a1 , x a2 , x a3 , y a1 , y a2 , y a3 are the three leaf basin-leaf back calibration sphere center XY axis coordinates measured by the linear laser respectively; x b1 , x b2 , x b3 , y b1 , y b2 , y b3 are the three leaf edge calibration sphere center XY axis coordinates measured by the linear laser respectively.

[0109] In step S302, the three-coordinate measuring instrument is used to measure the standard part to obtain a second point set;

[0110] The three-coordinate measuring instrument is used to measure the standard part to obtain a second point set, comprising:

[0111] The petiole part of the standard part is measured by the three-coordinate measuring instrument to determine petiole key points;

[0112] A blade coordinate system is established based on the petiole key points;

[0113] The three-dimensional point set under the blade coordinate system is obtained by measuring the leaf basin-leaf back calibration sphere group and the leaf edge calibration sphere group of the standard part by the three-coordinate measuring instrument respectively;

[0114] The second point set is obtained based on the dimension of the first point set and the three-dimensional point set.

[0115] First, the petiole part of the standard part is measured by the three-coordinate measuring instrument, and a measurement coordinate system consistent with the coordinate system of the theoretical model of the blade (i.e. the blade coordinate system) is established according to the measured petiole key point coordinates. In the blade coordinate system, the leaf basin-leaf back calibration sphere group 10 and the leaf edge calibration sphere group 11 are measured by the three-coordinate measuring instrument respectively to obtain the XYZ coordinates of the sphere centers of the calibration spheres. To ensure consistency with the data dimension of the first point set, the Z coordinates of the calibration sphere group measured by the three-coordinate measuring instrument are discarded, and finally the leaf basin-leaf back calibration sphere center point set C and the leaf edge calibration sphere center point set D under the blade coordinate system are obtained, i.e. the second point set:

[0116]

[0117] wherein x c1 , x c2 , x c3 , y c1 , y c2 , y c3X, Y, Z are respectively three leaf back calibration sphere center XY axis coordinates measured by a three-coordinate measuring instrument. d1 X, Y, Z d2 X, Y, Z d3 X, Y, Z d1 X, Y, Z d2 X, Y, Z d3 X, Y, Z are respectively three leaf edge calibration sphere center XY axis coordinates measured by a three-coordinate measuring instrument.

[0118] It should be noted that in the embodiment of the present application, the standard part is only measured once by the three-coordinate measuring instrument after the standard part is completed, and does not need to be measured again by the three-coordinate measuring instrument in subsequent use.

[0119] Step S303, determining the conversion relationship between the line laser coordinate system and the blade coordinate system according to the first point set and the second point set.

[0120] The conversion relationship between the line laser coordinate system and the blade coordinate system according to the first point set and the second point set comprises:

[0121] Subtracting the center point of each point in the first point set and the second point set respectively to obtain the first center point set and the second center point set;

[0122] Determining the covariance matrix according to the first center point set and the second center point set, and obtaining the rotation matrix and the translation matrix according to singular value decomposition.

[0123] Taking the leaf back calibration sphere group 10 of the standard part as an example, the point set A in the line laser coordinate system and the point set C measured by the three-coordinate measuring instrument in the blade coordinate system, the point set C and the point set A satisfy:

[0124] C=R·A+T

[0125] Wherein, R is the rotation matrix between the line laser coordinate system and the blade coordinate system, and T is the translation matrix between the line laser coordinate system and the blade coordinate system.

[0126] The center points of the point set A and the point set C are:

[0127]

[0128] Wherein, centroidA is the center point of the point set A, X, Y are respectively the X coordinate and the Y coordinate of the center point. CentroidB is the center point of the point set C, X, Y are respectively the X coordinate and the Y coordinate of the center point.

[0129] Subtract the center point of the point set A, centroidA, from each point in the point set A, and subtract the center point of the point set C, centroidB, from each point in the point set C. Obtain the point set A1 whose center of the whole point set A is moved to the origin, and obtain the point set C1 whose center of the whole point set C is moved to the origin.

[0130]

[0131] Determine the covariance matrix H of the two point sets A1 and C1 moved to the origin, and use singular value decomposition (SVD):

[0132]

[0133] [U, S, V] = SVD (H)

[0134] where H is the covariance matrix, C1 T is the transpose of the point set C1, [U, S, V] is the result of SVD decomposition of the covariance matrix H, U is an orthogonal matrix, S is a diagonal matrix, and V is the transpose of an orthogonal matrix.

[0135] Finally, the rotation matrix T and the translation matrix R can be obtained.

[0136]

[0137] where VU T is the transpose of the orthogonal matrix U.

[0138] The first point set is obtained by measuring the standard part with a line laser, the second point set is obtained by measuring the standard part with a coordinate measuring machine, and the conversion relationship is obtained. The point cloud data of each part of the to-be-measured blade can be accurately spliced, and the problem that the precision of splicing the data collected by multiple line laser devices cannot meet the high-precision measurement requirements of aviation blades and the like is solved. The common point cloud matching data processing method has the disadvantage of poor effect on high-complexity surfaces.

[0139] Step S400, measuring the to-be-measured blade according to the line laser measurement method to obtain complete point cloud of the cross-sectional profile of the to-be-measured blade;

[0140] Specifically, according to the line laser measurement method in step S100, the measurement point cloud of the cross-sectional profile of the blade at a certain z-axis coordinate is measured first, and then the z-axis coordinate is sequentially measured to obtain the complete point cloud of the cross-sectional profile of the to-be-measured blade.

[0141] Step S500, converting the complete point cloud of the cross-sectional profile of the to-be-measured blade to the blade coordinate system according to the conversion relationship, and determining the machining allowance according to the blade theoretical model and the point cloud converted to the blade coordinate system.

[0142] The measurement point clouds of the left leaf edge, the right leaf edge, and the measurement points of the leaf basin and the leaf back obtained by the line laser group are converted to the leaf coordinate system under the XY plane through the conversion relationship (rotation matrix and translation matrix) between the line laser coordinate system and the leaf coordinate system, and finally the complete data point cloud of the measured leaf complete section can be converted to the leaf coordinate system.

[0143] For example: the leaf basin data point cloud yb_mea line measured by the line laser group blade .

[0144] yb_mea blade =R*yb_mea line +T

[0145] The conversion relationship between other measurement regions in the two coordinate systems is the same, and accordingly the complete point cloud of the measured leaf section surface under the leaf coordinate system can be obtained.

[0146] As shown in Figure 5 , 12 is the cross-sectional surface of the theoretical model of the blade, i.e. the theoretical cross-sectional surface, and 13 is the cross-sectional surface composed of the measurement point cloud of the actually processed blade, i.e. the measurement point cloud of the actually processed blade. The machining allowance of the blade to be measured, i.e. the distance from the measurement point cloud 13 of the actually processed blade to the theoretical cross-sectional surface 12, can be obtained by the radius search method.

[0147] Specifically, the radius search method includes the following steps:

[0148] Step 1, determine the search region: starting from a measurement point in the measurement point cloud of the blade to be measured, set an initial search radius, and determine a circular search region with the point as the center and the initial search radius as the radius.

[0149] Step 2, search for the minimum distance: randomly generate a certain number of sample points in the search region, calculate the distances of these sample points to the theoretical cross-sectional surface of the blade, and record the minimum distance and the corresponding sample point.

[0150] Step 3, update the search radius: if the minimum distance found is less than the current search radius, it means that the minimum distance of the point to the theoretical cross-sectional surface of the blade may be within the current search region, so the search radius is reduced and step 2 is repeated; if the minimum distance is greater than or equal to the current search radius, the search radius is expanded and step 1 is repeated.

[0151] Step 4, convergence: when the search radius is small enough or the minimum distance meets certain accuracy requirements, the search is considered to have converged, and the minimum distance is returned to obtain the machining allowance of the measurement point.

[0152] Step 5, summarizing: repeating steps 1-5 above to obtain the machining allowance of the to-be-measured blade at each point on the blade.

[0153] The in-situ measurement method of the present application determines the conversion relationship between the blade coordinate system and the line laser coordinate system based on the blade theoretical model, three-coordinate measurement and line laser measurement method, and the conversion relationship is determined at one time without repeated calibration. The to-be-measured blade measurement point cloud measured by the line laser measurement can be converted to the blade coordinate system, which is used to obtain the machining allowance of the blade theoretical model, and the in-situ measurement is realized quickly, efficiently and accurately.

[0154] The implementation basis of each embodiment of the present application is realized by programmed processing of a device with processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present application can be packaged into various modules. Based on this actual situation, on the basis of the above embodiments, the embodiments of the present application provide a blade multi-line laser standard part in-situ measurement system, which is used to execute one of the blade multi-line laser standard part in-situ measurement methods in the above method embodiments.

[0155] The system comprises:

[0156] A first main module is used to construct a blade theoretical model, divide a measurement region of the blade according to the blade theoretical model and line laser measurement characteristics, and determine a line laser measurement method of the blade according to the divided measurement region;

[0157] A second main module is used to manufacture a standard part according to the specification of the to-be-measured blade, the blade theoretical model and the line laser measurement method;

[0158] A third main module is used to measure the standard part by a three-coordinate measuring instrument and a line laser measurement method respectively, and determine the conversion relationship between the line laser coordinate system and the blade coordinate system;

[0159] A fourth main module is used to measure the to-be-measured blade according to the line laser measurement method, and obtain complete point cloud of a cross-sectional surface of the to-be-measured blade;

[0160] A fifth main module is used to convert the complete point cloud of the cross-sectional surface of the to-be-measured blade to the blade coordinate system according to the conversion relationship, and determine the machining allowance according to the blade theoretical model and the point cloud converted to the blade coordinate system.

[0161] It should be noted that the device in the system embodiment provided by the present application can be used to implement the method in the above method embodiment, and can also be used to implement the method in other method embodiments provided by the present application. The difference is only that the corresponding function modules are set, and the principle is basically the same as that of the above device embodiment provided by the present application. As long as the person skilled in the art improves the device in the above system embodiment on the basis of the above device embodiment, refers to the specific technical solutions in other method embodiments, obtains the corresponding technical means by combining technical features, and the technical solutions formed by these technical means, on the premise of ensuring the practicability of the technical solutions, the corresponding system class embodiment can be obtained, which is used to implement the method in other method class embodiments.

[0162] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be realized by means of software and necessary general hardware platform, and of course, it can also be realized by hardware. Based on such understanding, the above technical solutions or the essential part of the prior art can be embodied in the form of a software product, which can be stored in a computer readable storage medium such as ROM / RAM, magnetic disk, optical disk, etc., and includes a plurality of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute the method described in each embodiment or some parts of the embodiment.

[0163] The flowcharts and block diagrams in the drawings show the possible implementation architecture, function and operation of the system, method and computer program product according to the embodiments of the present application. Based on this understanding, each block in the flowchart or block diagram can represent a module, program segment or part of code, which includes one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementations, the functions marked in the blocks can also occur in different order from that marked in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be realized by a dedicated hardware-based system for executing the specified function or action, or can be realized by a combination of special-purpose hardware and computer instructions.

[0164] In this patent, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0165] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for in-situ measurement of blade multi-line laser standard parts, characterized in that: include: Construct a blade theoretical model, divide the blade into measurement areas according to the blade theoretical model and line laser measurement characteristics, and determine the blade line laser measurement method according to the divided measurement areas; Produce standard parts according to the specifications of the blade to be measured, the blade theoretical model and the line laser measurement method; The standard parts were measured by three-coordinate measuring machine and line laser measurement method respectively to determine the conversion relationship between line laser coordinate system and blade coordinate system; The blade to be measured is measured using a line laser measurement method to obtain a complete point cloud of the cross-sectional profile of the blade to be measured; The complete point cloud of the blade cross-section to be measured is converted into the blade coordinate system according to the conversion relationship, and the machining allowance is determined according to the blade theoretical model and the point cloud converted into the blade coordinate system.

2. The in-situ measurement method for blade multi-line laser standard parts according to claim 1 is characterized in that: The method of dividing the blade into measurement areas according to the blade theoretical model and the line laser measurement characteristics includes: The blade measurement area is divided according to the line laser measurement range, the measurement curvature and the shape characteristics of the blade theoretical model cross-sectional profile, and the measurement area includes: blade basin, blade back, left blade edge and right blade edge.

3. The in-situ measurement method for blade multi-line laser standard parts according to claim 2 is characterized in that: The line laser measurement method for determining a blade according to the divided measurement areas includes: A measurement group consisting of two line laser transmitters is used to measure the left blade edge, and a single line laser transmitter is used to measure the blade basin; With the z-axis as the center, the blade rotates 180 degrees as a whole; A measurement group consisting of two line laser transmitters is used to measure the right edge of the blade, and a single line laser transmitter is used to measure the back of the blade; The measured data are spliced ​​together to obtain the complete cross-sectional profile data of a point on the z-axis. The blade is moved along the z-direction and the above steps are repeated to obtain the complete profile data of the blade body. The measurement range of any line laser emitter is larger than the size of any corresponding measurement area.

4. The in-situ measurement method for blade multi-line laser standard parts according to claim 3 is characterized in that: The method of manufacturing a standard part according to the specifications of the blade to be measured, the blade theoretical model and the line laser measurement method includes: Obtain the specification parameters of the standard petiole according to the specification parameters of the petiole of the leaf to be tested; Determine the installation position of the blade basin and blade back calibration ball set on the standard part according to the measurement range of the line laser transmitter corresponding to the blade basin and blade back; The installation position of the blade edge calibration ball group on the standard part is determined according to the measurement range of the line laser transmitter of the line laser group for measuring the left and right blade edges.

5. The in-situ measurement method for blade multi-line laser standard parts according to claim 4 is characterized in that: The method of measuring the standard parts by using a three-coordinate measuring machine and a line laser measuring method respectively, and determining the conversion relationship between the line laser coordinate system and the blade coordinate system, includes: The standard part is measured according to the line laser measurement process to obtain a first point set; The standard part is measured using a three-coordinate measuring machine to obtain a second point set; The conversion relationship between the line laser coordinate system and the blade coordinate system is determined according to the first point set and the second point set.

6. The in-situ measurement method for blade multi-line laser standard parts according to claim 5 is characterized in that: The step of measuring the standard part according to the line laser measurement process to obtain a first point set includes: The blade base and blade back calibration sphere groups and the blade edge calibration sphere group of the standard parts are measured respectively using a line laser transmitter to obtain the contour coordinates of the calibration spheres of the blade base and blade back calibration sphere groups and the blade edge calibration sphere group; The sphere centers are fitted according to the calibration sphere contour coordinates of the leaf basin and leaf back calibration sphere group and the leaf edge calibration sphere group, and the sphere center coordinates of the leaf basin and leaf back calibration sphere group and the leaf edge calibration sphere group are obtained, and the first point set is obtained by combining them.

7. The in-situ measurement method for blade multi-line laser standard parts according to claim 6 is characterized in that: The method of measuring the standard part with a three-coordinate measuring machine to obtain a second point set includes: Use a three-coordinate measuring machine to measure the petiole of the standard part and determine the key points of the petiole; Establish the leaf coordinate system based on the key points of the petiole; The blade base and blade back calibration spheres and the blade edge calibration spheres of the standard parts are measured by three-dimensional coordinate measuring machine to obtain the three-dimensional point set in the blade coordinate system. Based on the dimension of the first point set and the three-dimensional point set, a second point set is obtained.

8. The in-situ measurement method for blade multi-line laser standard parts according to claim 7 is characterized in that: Determining the conversion relationship between the line laser coordinate system and the blade coordinate system according to the first point set and the second point set includes: Subtract the center point from each point in the first point set and the second point set to obtain the first center point set and the second center point set; A covariance matrix is ​​determined according to the first center point set and the second center point set, and a rotation matrix and a translation matrix are obtained according to singular value decomposition.

9. The in-situ measurement method for blade multi-line laser standard parts according to claim 1, characterized in that: Determining the machining allowance according to the blade theoretical model and the point cloud converted to the blade coordinate system includes: determining the machining allowance based on a radius search method according to the blade theoretical model and the point cloud converted to the blade coordinate system.

10. A blade multi-line laser standard component in-situ measurement system, characterized in that: include: The first main module is used to construct a blade theoretical model, divide the blade into measurement areas according to the blade theoretical model and line laser measurement characteristics, and determine the line laser measurement method of the blade according to the divided measurement areas; The second main module is used to produce standard parts according to the specifications of the blade to be measured, the blade theoretical model and the line laser measurement method; The third main module is used to measure the standard parts using a three-coordinate measuring machine and a line laser measurement method, and determine the conversion relationship between the line laser coordinate system and the blade coordinate system; The fourth main module is used to measure the blade to be measured according to the line laser measurement method to obtain a complete point cloud of the cross-sectional profile of the blade to be measured; The fifth main module is used to convert the complete point cloud of the blade cross-section profile to be measured into the blade coordinate system according to the conversion relationship, and determine the machining allowance according to the blade theoretical model and the point cloud converted to the blade coordinate system.

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